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Part of The Adaptation-Mitigation Dilemma: Is Nuclear Power a Practical Solution for Climate Change?

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THE ADAPTATION-MITIGATION DILEMMA:
IS NUCLEAR POWER A PRACTICAL SOLUTION
FOR CLIMATE CHANGE?

by
Natalie Kopytko

A Thesis
Submitted in partial fulfillment
of the requirements for the degree
Master of Environmental Studies
The Evergreen State College
June 2009

© 2009 Natalie Kopytko. All rights reserved.

This Thesis for the Master of Environmental Studies Degree
by
Natalie Kopytko
has been approved for
The Evergreen State College
by

-------------------------------Dr. John Perkins
Member of the Faculty Emeritus
-------------------------------Dr. Greg Stewart
Geomorphologist/Hydrologist
-------------------------------Michael Mariotte
Executive Director of Nuclear Information and Resource Service

----------------------------Date

ABSTRACT
The Adaptation-Mitigation Dilemma:
Is Nuclear Power A Practical Solution For Climate Change?
Natalie Kopytko
According to recent evidence, the impacts of global climate change are now being
felt. Synergies and tradeoffs exist between adaptation and mitigation measures
needed to address those impacts, yet insufficient research exists in this arena.
Criteria developed in this study evaluated nuclear power as a mitigation practice.
Coastal and inland reactors were studied separately to account for different
climate impacts at each location. GIS analysis modeled inundation from sea level
rise for all nine coastal reactors in the U.S. within 2 miles of the Pacific and
Atlantic oceans. Reports from the U.S. Nuclear Regulatory Commission provided
supplementary information on operational responses and problems encountered
during coastal storms. Sea level rise models revealed that nuclear power plants in
Florida are the most vulnerable to inundation, followed by nuclear power plants in
the northeast. Safety stands out as the primary concern at all coastal locations.
Heat waves, drought, flooding, and biological fouling affect reactors located on
inland water bodies in France, the United States, and Canada. Thermal pollution
and legal water battles already affect inland reactors, and the expense of changing
cooling systems to use less water at inland sites will make many locations
uneconomical for nuclear power. This study demonstrates that applying the
criteria to inland and coastal nuclear power plants reveals several significant
weaknesses of nuclear power as a mitigation measure for climate change.
Cumulatively, these weaknesses make nuclear power an unsuitable mitigation
strategy for climate change. Additionally, this analysis underscores the
importance of considering the interaction of adaptation and mitigation strategies
for climate impacts at the regional level.

Table of Contents
Executive Summary .................................................................................................1
1. Nuclear Power and Climate Change ....................................................................3
1.1. Reactor Operation, Design and the Environment .........................................7
1.1.1. Cooling Systems ....................................................................................8
1.1.2. External Events and the Design of Nuclear Power Plants ...................12
1.2. The Influence of Climate Change on Nuclear Power Plants ......................13
1.2.1. Flooding and Storm Damage ...............................................................16
1.2.2. Availability of Cooling Water .............................................................17
1.3. The Nuclear Choice ....................................................................................18
Part I Coastal Climate Impacts ..........................................................................21
2. Coastal Hazards Background .............................................................................22
2.1. Sea level Rise ..............................................................................................22
2.2. Coastal Storms ............................................................................................25
2.3. Shoreline Erosion and Coastal Defenses ....................................................30
3. Coastal Methods.................................................................................................33
3.1. Sea Level Rise Methods..............................................................................34
3.2. Literature Review of Nuclear Operations at Coastal Sites .........................43
4. Coastal Results ...................................................................................................44
4.1. Sea Level Rise Model Results ....................................................................44
4.1.1. St. Lucie ...............................................................................................44
4.1.2. Crystal River ........................................................................................49
4.1.3. Turkey Point.........................................................................................53
4.1.4. Seabrook Station ..................................................................................59
4.1.5. Pilgrim Station .....................................................................................65
4.1.6. Millstone ..............................................................................................71
4.1.7. Calvert Cliffs ........................................................................................77
4.1.8. San Onofre ...........................................................................................82
4.1.9. Diablo Canyon .....................................................................................85
4.1.10. Sea Level Rise and Coastal Vulnerability Discussion .......................88
4.2. Operational Experience ...............................................................................91
4.3. Design Concerns .........................................................................................96
Part II Inland Climate Impacts ........................................................................100
5. Inland Climate Concerns Background .............................................................101
5.1. Heat Waves ...............................................................................................102
5.2. Precipitation ..............................................................................................105
5.3. Water Quality and Aquatic Ecosystems ...................................................110
6. Inland Methods ................................................................................................112
7. Inland Results...................................................................................................115
7.1. Flooding of Nuclear Power Plants in France ............................................115
7.2. Heat Waves and Drought in France ..........................................................119
7.3. Drought and Heat Waves in the United States..........................................127
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7.4. Biological Fouling in Canada and the United States ................................135
8. Discussion ........................................................................................................141
8.1. Evaluation of Nuclear Power ....................................................................141
8.1.1. Interrupted Operation .........................................................................141
8.1.2. Financial Costs ...................................................................................142
8.1.3. Adaptation Impairment – Human Systems ........................................143
8.1.4. Adaptation Impairment – Natural Systems ........................................144
8.1.5. Other Environmental Problems..........................................................144
8.1.6. Is Nuclear Power A Practical Solution To Climate Change? ............146
8.2. The Adaptation-Mitigation Dilemma .......................................................147
Literature Cited ....................................................................................................150
Appendix 1. Fission and Nuclear Power Plants ...................................................172
Appendix 2. Reactor Types..................................................................................174
Appendix 3. Ultimate Heat Sink ..........................................................................176
Appendix 4. Evaluating Sites for Nuclear Power Plants .....................................178
Appendix 5. External Events and Nuclear Power Plant Design ..........................180
Appendix 6. New Reactor Design and Research Goals .......................................185
Appendix 7. Nuclear Power as a Mitigation Measure for Climate Change.........187
Appendix 8. Coastal Vulnerability Methods .......................................................189
Appendix 9. Coastal Vulnerability Data ..............................................................191

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List of Figures
Figure 1. Location of coastal reactors analyzed for vulnerability to sea level rise. ...
……………………………………………………………………………………35
Figure 2. Satellite imagery of St. Lucie with Digital Elevation Model overlay. ...45
Figure 3. St. Lucie with a sea level rise of 0.3 m and 0.4 m. .................................47
Figure 4. St. Lucie with a sea level rise of 0.6 m and 0.7 m. .................................48
Figure 5. Satellite imagery of Crystal River with Digital Elevation Model overlay.
……………………………………………………………………………………50
Figure 6. Crystal River with a sea level rise of 1 m and 2 m. ................................52
Figure 7. Satellite imagery of Turkey Point with Digital Elevation Model overlay.
……………………………………………………………………………………54
Figure 8. Turkey Point with a sea level rise of 0.4 m and 0.5 m. ..........................56
Figure 9. Turkey Point with a sea level rise of 0.9 m. ...........................................57
Figure 10. Turkey Point with a sea level rise of 2.5 m. .........................................58
Figure 11. Satellite imagery of Seabrook Station with Digital Elevation Model
overlay....................................................................................................................60
Figure 12. Seabrook Station with a sea level rise of 1 m. ......................................62
Figure 13. Seabrook Station with a sea level rise of 3 m. ......................................63
Figure 14. Seabrook Station with a sea level rise of 6 m. ......................................64
Figure 15. Satellite imagery of Pilgrim Station with Digital Elevation Model
overlay....................................................................................................................66
Figure 16. Pilgrim Station with a sea level rise of 1 m. .........................................68
Figure 17. Pilgrim Station with a sea level rise of 4 m. .........................................69
Figure 18. Pilgrim station with a sea level rise of 6 m and 7 m.............................70
Figure 19. Satellite imagery of Millstone with Digital Elevation Model overlay. 72
Figure 20. Millstone with a sea level rise of 2 m and 3 m. ....................................74
Figure 21. Millstone with a sea level rise of 4 m. ..................................................75
Figure 22. Millstone site with a sea level rise of 6 m. ...........................................76
Figure 23. Satellite imagery of Calvert Cliffs with Digital Elevation Model
overlay....................................................................................................................78
Figure 24. Calvert Cliffs with a sea level rise of 3.9 m. ........................................80
Figure 25. Calvert Cliffs with a sea level rise of 4.6 m. ........................................81
Figure 26. Satellite imagery of San Onofre with Digital Elevation Model overlay. .
……………………………………………………………………………………83
Figure 27. Satellite imagery of Diablo Canyon with Digital Elevation Model
overlay....................................................................................................................86
Figure 28. Nuclear power plants currently operating in the United States. .........114

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List of Tables
Table 1. The consequences of climate impacts for coastal reactors. .....................13
Table 2. The consequences of climate impacts for inland reactors. ......................14
Table 3. Criteria and indicators used to evaluate nuclear power plants at coastal
locations. ................................................................................................................34
Table 4. Description of time-frames used in sea level rise modeling. ...................36
Table 5. Scenario description and corresponding quantity of sea level rise for
California and Florida, and the Northeast region...................................................37
Table 6. The Saffir-Simpson Hurricane Scale (National Weather Service, 2007).38
Table 7. Coordinates for reactors included in sea level rise analysis. ...................39
Table 8. Resolution of Digital Elevation Models. .................................................41
Table 9. Example of sea level rise results table.. ...................................................42
Table 10. Sea level rise scenarios and results for St. Lucie. ..................................46
Table 11. Relative vulnerability of each of the coastal variables and overall
vulnerability of the coastline at St. Lucie. .............................................................46
Table 12. Sea level rise scenarios and results for Crystal River. ...........................51
Table 13. Relative vulnerability of each of the coastal variables and overall
vulnerability of the coastline at Crystal River. ......................................................51
Table 14. Sea level rise scenarios and results for Turkey Point. ...........................55
Table 15. Relative vulnerability of each of the coastal variables and overall
vulnerability of the coastline at Turkey Point. .......................................................55
Table 16. Sea level rise scenarios and results for Seabrook Station. .....................61
Table 17. Relative vulnerability of each of the coastal variables and overall
variability of the coastline at Seabrook Station. ....................................................61
Table 18. Sea level rise scenarios and results for Pilgrim Station. ........................67
Table 19. Relative vulnerability of each of the coastal variables and overall
vulnerability of the coastline at Pilgrim Station. ...................................................67
Table 20. Sea level rise scenarios and results for Millstone. .................................73
Table 21. Relative vulnerability of each of the coastal variables and overall
vulnerability of the coastline at Millstone. ............................................................73
Table 22. Sea level rise scenarios and results for Calvert Cliffs. ..........................79
Table 23. Relative vulnerability of each of the coastal variables and overall
variability of the coastline at Calvert Cliffs. ..........................................................79
Table 24. Sea level rise scenarios and results for San Onofre. ..............................84
Table 25. Relative vulnerability of each of the coastal variables and overall
vulnerability of the coastline at San Onofre. .........................................................84
Table 26. Sea level rise scenarios and results for Diablo Canyon. ........................87
Table 27. Relative vulnerability of each of the coastal variables and overall
vulnerability of the coastline at Diablo Canyon. ...................................................87
Table 28. Summary of results for flooding due to sea level rise and coastal
vulnerability. ..........................................................................................................89
Table 29. Wind designs for nuclear power plants that are in the direct path of
hurricanes . .............................................................................................................97
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Table 30. Criteria and indicators used to evaluate nuclear power plants located at
inland sites. ..........................................................................................................114
Table 31. France’s inland reactors and sites issued thermal release waivers. .....122

viii

Acknowledgments
This thesis would have never happened if it were not for one informative
and influential class: Chernobyl and Ukraine: Recovery from Catastrophe and the
Future of Nuclear Power. Thank-you to John Perkins and Tanya Murza for
sharing their passion on the subject, organizing a remarkable group of presenters,
and being brave enough to take students overseas. I also want to thank my
Chernobyl classmates whose intellectual curiosity and passion made the
experience all the more rewarding.
I must also thank John Perkins for his work as my thesis reader and the
valuable feedback he gave during the entire writing process. Thanks to Greg
Stewart for his advice on the organization of my thesis and for his assistance in
using ArcGIS. Thanks to Michael Mariotte for suggesting this as a thesis topic to
our class, and for providing valuable details on the nuclear industry.
I’d like to acknowledge all the support I received from my fellow MES
classmates, in particular Kathleen Saul who also caught the nuclear bug from the
Chernobyl class. Several people were helpful not only in answering questions,
but their enthusiasm for the topic provided wonderful encouragement including:
Dominique Bachelet, Mary Lampert, and Dave Lochbaum. I’d also like to thank
the following organizations for their assistance and for fantastic work in climate
change and/or nuclear power: Nuclear Information Resource Services (NIRS),
The Union of Concerned Scientists, Pilgrim Watch, and The Nature Conservancy.
Thanks to Judy Cushing and my co-workers in the Scientific Database lab for
their support, and for animating my sea level rise visualizations. Last but not least
thanks to all my family and friends for their support especially my husband Lyle
Higgs.

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Executive Summary
Humanity must live with the consequences of climate change now. Mitigation
alone will no longer be enough to address climate change; therefore countries must also
adapt. Synergies and tradeoffs exist between adaptation and mitigation; yet insufficient
research exists in this arena. The Adaptation-Mitigation Dilemma applies to two broad
adaptation problems that afflict mitigation projects. First, mitigation projects must adapt
to climate change to continue operating. Second, mitigation projects can impair the
ability of systems to adapt to climate change or cause other environmental problems. In
this study, five criteria were developed specifically to evaluate these two problems and
used to assess nuclear power as a mitigation practice.
The criteria evaluate the consequences of climate change for the mitigation
measure. First, can climate change block the continued operation of the mitigation
measure? Next, are the financial costs needed to adapt the mitigation measure for
climate change prohibitively high? In addition, the criteria evaluate the consequences of
the mitigation measure to the environment. Does continued operation of the mitigation
measure impair the ability of natural systems to adapt? Does continued operation impair
the ability of human systems to adapt? Can climate change cause the mitigation practice
to create other health or environmental problems? In the case of nuclear power, this last
criterion identifies safety concerns and increased probability of accidents due to climate
impacts on the operation of nuclear power plants.
Coastal and inland reactors were studied separately to account for different
climate impacts at each location. The coastal portion of the study focused on reactors in
the United States. GIS analysis modeled inundation from sea level rise for all nine
coastal reactors within 2 miles of the Pacific and Atlantic oceans. In many coastal
regions erosion processes pose a greater threat than inundation; therefore, relative coastal
vulnerability data from the U.S. Geological Survey for the nine coastal reactors was
included in the analysis. Hurricanes also pose problems for reactors located several miles
from the coastline particularly in estuarine sites. Reports from the U.S. Nuclear
Regulatory Commission provided information on operational responses and problems
encountered during coastal storms.
Sea level rise models revealed that nuclear power plants in Florida are the most

1

vulnerable to inundation followed by nuclear power plants in the northeast. Calvert
Cliffs in Maryland has some flooding under the most severe conditions, while reactors in
California are not threatened by inundation. However, San Onofre in California and
Calvert Cliffs in Maryland received a high and very high ranking respectively according
to the coastal vulnerability index. Therefore, development at these sites impedes the
ability of natural and human systems to adapt to changes in the coastal environment.
In terms of climate impacts, hurricanes currently pose the greatest threat to safe
operation. Several issues pertaining to safety arise during storms including: loss of offsite power, loss of communications, blockage of evacuation routes, and equipment
malfunction. Frequently reactors must be shutdown during hurricanes and restart of
reactors can take weeks. Evacuations and damage to transmission lines, however,
ensures low customer demand during these storm emergencies.
The inland portion of the analysis focused on the operation of nuclear power
plants in the United States, France and Canada. The United States with 104 reactors has
the largest nuclear fleet in the world. France generates the largest proportion of its
energy supply, approximately 80%, from nuclear power. Canada receives a small
proportion of energy from nuclear power. The province of Ontario, however, receives
50% of its energy from nuclear.
Heat waves, drought, flooding, and biological fouling affect reactors located on
inland water bodies. Additionally, the experiences of nuclear operation in each of these
countries provide unique insights into climate impacts. France has encountered problems
exceeding design capacities with summer droughts, heat waves, and floods. Drought and
heat waves posed problems for reactor operation in the U.S. particularly in the
southeastern states. Reactors along the Great Lakes, in both Canada and the U.S.,
continue to have problems with biological fouling due to Cladophora. Regulatory
agency reports, utility company reports, and legal documents allowed evaluations of
climate impacts at inland locations.
When reactors must shutdown during heat waves it occurs at a time of peak
energy demand. During heat waves in France issuing of thermal release waivers in
excess of environmental regulations assured a reliable supply of energy. Thermal
pollution, however, reduces the ability of aquatic ecosystems to adapt to warmer
temperatures. In the United States legal water battles between states occurred in regions

2

with nuclear power, such as the Catawba River Basin in the Carolinas and the Lake
Lanier/Chattahoochee River system. These battles indicate water scarcity concerns and
problems with adapting human systems to a reduced supply of water. Newly constructed
reactors could use dry or hybrid cooling systems; the energy and financial costs to run
these systems, however, are likely prohibitive. Adapting flood protection devices can
also be costly: Raising the dyke by 1 m at the Belleville site in France cost over 13
million U.S. dollars. Safety supersedes cost concerns when dealing with flooding.
Flooding in excess of historical levels impairs safety in multiple ways, similar to
hurricanes, but without the benefit of anticipation and preparation. In a similar manner,
biological fouling causes revenue losses and safety problems due to the inability to
predict its occurrence.
Applying the criteria to inland and coastal nuclear power plants reveals several
weaknesses of nuclear power as a mitigation measure for climate change. Safety stands
out as the primary concern at coastal locations. Adaptation problems from sea level rise
are almost certain. Thermal pollution and legal water battles already affect inland
reactors. The expense of changing cooling systems to use less water at inland sites will
make many locations uneconomical for nuclear power. The culmination of this analysis
underscores the importance of considering climate impacts at the regional level.
Decisions on adaptation and mitigation to climate change must, therefore, also be made at
the regional level by taking account of projected interactions between nuclear power and
climate change. A national or international push for particular mitigation strategies will
unfortunately, likely overlook regional events and effects.

1. Nuclear Power and Climate Change
Climate change, due largely to emissions from burning fossil fuels, presents one
of the greatest challenges the world faces today. Posited as a solution to climate change,
nuclear power could replace some of the energy currently generated by burning fossil
fuels. However, climate change permeates every facet of humanity; therefore, many
factors must be considered in addressing this problem. Due to the complexity of the
climate change, it was recognized that policymakers needed an objective source of
information about the causes of climate change, its potential environmental and socio-

3

economic consequences and the adaptation and mitigation options to respond to it. The
Intergovernmental Panel on Climate Change (IPCC) was established by the World
Meteorological Organization and by the United Nations Environment Program to fill this
need (2007a).
Adaptation and mitigation are two distinct, but equally important measures that
reduce the impacts of climate change. An impact describes a specific change in a system
caused by its exposure to climate change. Vulnerability to climate change is the degree to
which systems are susceptible to, and unable to cope with the adverse impacts (Schneider
et al., 2007).
Mitigation reduces the sources or enhances the sinks of greenhouse gases,
thereby, diminishing the severity of climate impacts (IPCC, 2001). Adaptation is an
adjustment in natural or human systems in response to actual or expected climatic stimuli
or their effects, which moderates harm or exploits beneficial opportunities (IPCC, 2001).
Adaptation diminishes the vulnerability of the system. Nuclear power is viewed as one
option for mitigation, because it emits little greenhouse gas during the generation of
electricity.
Climate change, however, can no longer be avoided; the consequences are being
felt now and will continue to be felt due to current emissions, and the latent impacts from
greenhouse gases already in the atmosphere. According to the IPCC (2007b), warming of
the climate system is unequivocal, as is now evident from observed increases in global
average air and ocean temperatures, widespread melting of snow and ice and rising global
average sea level. Observational evidence from all continents and most oceans shows that
many natural systems are being affected by regional climate changes, particularly
temperature increases.
Human influences have:
• Very likely contributed to sea level rise during the latter half of the 20th century.
• Likely contributed to changes in wind patterns, affecting extra-tropical storm
tracks and temperature patterns.
• Likely increased temperatures of extreme hot nights, cold nights and cold days.
• More likely than not increased risk of heat waves, area affected by drought since
the 1970s and frequency of heavy precipitation events.
Evidence shows that with current climate change mitigation policies and related

4

sustainable development practices, global greenhouse gas emissions will continue to
grow over the next few decades. Moreover, for the next two decades a warming of about
0.2˚C per decade is projected regardless of emission levels. Beyond that timeframe
future warming depends on the level of greenhouse gas emissions (IPCC, 2007b).
Therefore, adaptation is necessary to cope with changes that will occur despite
mitigation efforts. While adaptation and mitigation are distinct responses to climate
change, the two approaches must be considered in concert. The implications of some
mitigation strategies for adaptation and other development and environment concerns
have been recognized, but remain unexplored. Moreover, information on
interrelationships between adaptation and mitigation at regional and sectoral levels is
scarce (Klein et al., 2007).
The Adaptation-Mitigation Dilemma pertains to the two broad adaptation problems
that arise in mitigating for climate change. First, adaptation poses a challenge to
mitigation projects because climate change impacts their operation. The mitigation
project must adapt to climate change or continued operation is threatened. Second,
operation of the mitigation measure can impair the ability of natural and human systems
to adapt, or cause other environmental concerns. In order to address these two problems, I
propose using the following criteria to judge any mitigation measure:
Interrupted Operation: Could climate change thwart the future operation of the
mitigation action?
Financial Costs: Does climate change increase the costs of the mitigating action?
Adaptation Impairment - Human Systems: Does operation of the mitigating action
have the potential to reduce the ability of human systems to adapt?
Adaptation Impairment - Natural Systems: Does operation of the mitigating action
have the potential to reduce the ability of natural systems to adapt?
Other Environmental Problems: Could climate impacts lead the mitigating action to
have other health or environmental problems?
These criteria were established because the consequences for each are significant. (1)
If the mitigation measure is no longer able to operate, then carbon-emitting sources of
energy may be used as a replacement thereby voiding any benefit. (2) Financial
resources are limited, so it is important to consider which projects provide the most
benefits with the least amount of cost. If climate change itself increases the cost of

5

operations of the mitigation strategy, the benefits might no longer outweigh the costs
and/or other mitigation options may become more financially attractive. (3) If the
mitigation measure compromises the ability of natural or human systems to adapt then it
can no longer be considered a solution to climate change. (4) The mitigation measure
adopted by one group could interfere with adaptation in another sector or a neighboring
state or nation. (5) Alternatively, adaptation could be impaired in the region that adopts
the mitigation measure. The benefit of mitigation is global; therefore, reducing the ability
to adapt places an inequitable burden on regions that adopt the particular mitigation
measure. (6) This holds true if the mitigation measure leads to other environmental
problems.
The primary objective of this thesis is to examine these issues for a particular
mitigation measure: nuclear power. The results of this thesis show that nuclear power
has various vulnerabilities to climate change that diminish the ability of nuclear power to
act as a mitigating agent and impair the ability of systems to adapt. Nuclear power plants
are sited either along large inland bodies of water or close to the coast due to the need for
large volumes of cooling water. Each of these environments has unique challenges and
therefore impacts at coastal and inland locations are considered separately. Sea-level rise
(as the climate warms and glacial and polar ice melts) threatens the stability and
operations of nuclear power plants located on shorelines. Warmer temperatures may
force shut-downs of nuclear power plants located on inland waters, (a) if the water
temperature increases, (b) water quantity decreases, or (c) biological fouling occurs
because of ecosystem changes. Hurricanes and intense precipitation events also pose a
threat to the operation of nuclear plants.
Geographic Information System (GIS) models show that a number of reactors in the
United States are vulnerable to the sea-level rises predicted for the 21st century. A
literature review demonstrates that reactors on inland waters in the United States, France,
and Canada have already been affected by a warming climate. These findings
demonstrate that nuclear reactors located on both coastal and inland sites are vulnerable
to climate change; therefore, in terms of adaptation currently existing nuclear power
plants in many regions will not be a suitable mitigation of or solution for climate change.
The remainder of this introductory chapter reviews major features of nuclear reactors,
their design, their location, and how climate change will affect existing reactors. The final

6

section of this chapter addresses current obstacles to the expansion of nuclear power. Part
I of the thesis deals with coastal climate impacts, while Part II evaluates the impacts at
inland sites. Both Part I and Part II follow the same general format. First, a literature
review of climate science provides details on the past, current and future climatic
challenges at each of these locations. Next, the methods used to analyze climate impacts
on nuclear power plant operation are described. Finally, the results are presented. The
final chapter synthesizes the two pieces first by focusing on the climate impacts to
nuclear power and then by addressing the adaptation-mitigation dilemma in general.

1.1. Reactor Operation, Design and the Environment
Electricity production from nuclear power involves the transformation of kinetic
energy from fission into heat, the conversion of heat into steam, the utilization of steam
to rotate a turbine, and the conversion of the energy of rotation into electrical energy.
Alternatively, heated gas is used directly to rotate the turbine. The coolant transfers
energy from the hot fuel to the electrical turbine, either directly or through intermediate
steps. The coolant can be either a liquid or a gas: light water, heavy water, helium, and
carbon dioxide are the most common coolants. For a more detailed description of nuclear
power operation and components refer to Appendix 1. The type of coolant is one
determinant of reactor type as described in Appendix 2.
Turbo-generator systems that convert thermal energy to electrical energy are
termed heat engines. The maximum conversion efficiency of any heat engine, determined
by the laws of thermodynamics, is the Carnot efficiency expressed as: η = (Tin – Tout )/
Tin. Tin is the absolute temperature (K) of the gas entering the turbine and Tout is the
absolute temperature of the gases leaving the turbine. Therefore, more of the thermal
energy is converted to electrical energy with higher entering temperatures and/or lower
outlet temperatures. The inlet temperature is limited by the water/ steam pressure rating
of the boiler or reactor vessel in a steam cycle, or by the temperature limitations of the
turbine blades, while the outlet temperature is limited by the ambient temperature of the
cooling water used in the condenser of a steam cycle (Shultis & Faw, 2008). The
conversion efficiency is the ratio of electrical power to thermal power and provides an
important measure of a power plant's performance. In modern nuclear power plants,
conversion efficiencies of about 40% can be achieved; fossil-fired units can achieve only

7

slightly greater efficiencies, while older plants efficiencies range from 30-35% (Shultis &
Faw, 2008).
In a nuclear reactor the coolant has an additional importance. Since radioactive
decay causes heat production to continue even after the reactor is shut down and
electricity generation has stopped, it is essential to maintain cooling to avoid melting the
reactor core. Furthermore, the power level at which a reactor can operate safely is
limited by the rate at which the primary coolant can carry away the heat generated in the
reactor core (Mounfield, 1991). If heat is generated at a rate faster than it is carried away
by the coolant, the fuel would overheat and could melt or vaporize. Efficient and safe
operation of a nuclear power plant is dependent on the coolant which in turn is dependent
on the cooling system.

1.1.1. Cooling Systems
The cooling systems are vital to the safe operation and shutdown of nuclear
reactors. In addition, service water systems that use water from nearby water sources and
supplies are necessary to cool the equipment associated with the nuclear reactor such as
the chillers in air-conditioning units, heat exchangers, and lubricating oil coolers for the
main turbine (Lochbaum, 2007). The most significant cooling concerns are the ultimate
heat sink and condenser cooling.
The International Atomic Energy Agency (IAEA, 2004) defines the ultimate heat
sink as a medium to which the residual heat can always be transferred, even if all other
means of removing the heat have been lost or are insufficient. The ultimate heat sink is
normally a body of water, the groundwater or the atmosphere.
When water is the medium selected as the ultimate heat sink, the following
should be considered: size of the water supply, type of cooling water supply, make-up
sources to the ultimate heat sink, and capability of the heat sink to deliver the necessary
flow of cooling water at appropriate temperatures for operational states, accident
conditions or shutdown conditions of the reactor (IAEA, 2004).
Some member states of the IAEA require that both the ultimate heat sink and its
directly associated transport systems be designed with sufficient capability and capacity
to bring the plant to cold shutdown (90˚C at atmospheric pressure) within 36 hours
(IAEA, 1981). Furthermore, regulations in the United States stipulate that 30 days is the

8

required period for which the capacity of the sink should be sufficient to provide cooling.
Procedures should be available for ensuring the continued capability of the sink beyond
30 days (U.S. Nuclear Regulatory Commission, 1976).
Water and/or air may be chosen as the transport medium. The relative
dependability and capacity of available sources should be taken into account. In general,
access to natural, inexhaustible supplies of water such as oceans, large lakes, or large
rivers is preferable to limited-capacity man-made sources.
The sizing of the heat transport system directly associated with the ultimate heat
sink are governed by: the maximum heat rejection rate, environmental parameters for
design, and the supplies of coolant (IAEA, 1981, 2004). In determining the capacity of
the ultimate heat sink and its directly associated heat transport systems, design basis
environmental parameters must be established. These parameters include water
temperature of the ultimate heat sink for once-through water cooling systems, dry-bulb
temperature for dry cooling towers, and wet- and dry-bulb air temps for heat transport
systems which use evaporative cooling such as wet cooling towers, cooling or spray
ponds.
Consideration of critical time periods is particularly important in determining
capacity. Ponds require establishment of design basis environmental parameters based on
longer several days, while dry cooling tower are dependent only on dry bulb temperature
and the critical period may be much shorter (IAEA, 1981). Appendix 3 provides a more
thorough description of the requirements associated with the Ultimate Heat Sink.
Two basic types of cooling systems are used for condenser cooling: the oncethrough system and closed loop system. In the once-through cooling system, water is
circulated through the steam condenser once and the heated water is discharged directly
to the water body from which it was taken. Supplemental cooling by means of cooling
towers or cooling ponds may be necessary in order to dissipate heat directly to the
atmosphere before water is discharged to public waters (Eichholz, 1976). In closed
cooling systems, water is continuously circulated through the condensers. The water is
cooled through evaporation by means of towers, ponds, spray canals, or a combination of
measures. The water consumed is replaced with water taken from a water body. In
closed systems some water is discharged to the water body to prevent an excessive
buildup in the concentration of salts and plant chemicals in the circulating cooling water

9

and to maintain steady-state conditions in the quantity and quality of water used in
cooling (Eichholz, 1976; Giusti & Meyer, 1977).
The benefit of the closed-loop system is that it has very little warm-water
discharge to a receiving water body, since it is designed to dissipate the waste heat into
the atmosphere. The once-through cooling system has much higher water requirements;
however, less of the water is consumed compared to the closed-loop system. Oncethrough cooling systems with large cooling reservoirs can reject 40 percent of the excess
heat through evaporation, while cooling towers lose approximately 80 percent through
evaporation (J. Z. Reynolds, 1980). The choices in cooling systems have other tradeoffs
in efficiency and land use. For instance, the area required for locating physical facilities
on site may be as low as 15 acres per generating unit for sites with once-through cooling
but is typically in the 50-acre range when switchyard and cooling tower areas are
included (Burwell et al., 1979). Cooling ponds also consume land requiring 1-2 acres per
megawatt of installed capacity with a recommended minimum depth of 2-4 m (Eichholz,
1976). A spray pond requires smaller volume and surface areas compared to surface
cooled ponds, but at the same time increased evaporative water losses require additional
makeup water (Codell, 1981; Eichholz, 1976).
Cooling towers may be used to provide full cooling requirements only during
certain periods of the year and may be combined with cooling ponds as back-up systems.
Cooling towers and cooling ponds have limitations in the extent to which the temperature
of warm water can be reduced, due to the decrease in evaporative cooling as the wet bulb
temperature is approached; moreover, pond performance is affected by surface air
temperature, relative humidity, wind speed, wind fetch, solar radiation, aquatic growth
and erosion (Eichholz, 1976). These factors lead to performance reductions during hot
weather.
In addition to the environmental parameters that impede the efficiency of energy
generation, cooling systems require energy that lowers the output of the reactor. Cooling
towers reduce the overall efficiency of a power plant by 3-5% (Australian Uranium
Association, 2007). The efficiency is dependent on the type of cooling tower. Cooling
towers can be classified as dry or wet. In dry towers warm water is contained in pipes
and air flow cooling occurs primarily by conduction across the pipe interface, while in
wet towers the warm water is in direct contact with a flow of air and heat is dissipated

10

principally by evaporation. While dry cooling towers uses less than 10% of the water
required for wet cooling towers, they have a much greater cost for construction and
require approximately 0.5% to 1.5% of the power station’s output to run (Australian
Uranium Association, 2007; World Nuclear Association, 2008b). Cooling towers are
also classified by how the air flow is produced. Air flow can be induced by mechanical
draft, using one or more powerful fans, or natural draft, using a tall, typically
hyperbolically shaped "chimney," to provide a natural updraft (Eichholz, 1976). The
power requirements to provide the extra pumping power for circulation in mechanical
draft towers further reduce the effective efficiency value of the power plant; moreover,
problems from fogging and drift of discharged air requires distance from the plant
thereby increasing piping costs (Eichholz, 1976). In light of climate change, the costs of
cooling towers, dry cooling and lower thermal efficiencies for inland sites will be
significant and, in some cases, this may be sufficient to turn the economic balance against
nuclear (Kidd, 2008).
Cooling systems depend greatly on the type of reactor and some newer reactor
designs have very different needs. For example, the passive cooling design of the
Advanced Pressurized 1000 (AP1000) does not require a separate safety Ultimate Heat
Sink. Nonetheless, the high water requirements of nuclear power plants will continue at
least in the near future. For instance, the Pebble Bed Modular Reactor (PBMR) is
estimated to need 724,974 gallons per minute (gpm) for an 8-module plant if oncethrough cooling is used. If the plant uses mechanical draft cooling towers, the flow is
estimated at 260,991 gpm and makeup flow is estimated at 15,659 gpm (Dominion
Energy Inc. Betchel Power Corporation, 2002). The Advanced Pressurized 1000
(AP1000) is estimated to need between 450,000 to 750,000 gpm and makeup flow is
anticipated to be approximately 4%. Moreover, the service water for reactors such as the
AP1000 and International Reactor Innovative and Secure (IRIS) have separate cooling
towers that require from 250 to 500 gpm (Dominion Energy Inc. Betchel Power
Corporation, 2002).
Solutions to thermal waste from nuclear power plants will continue to be
determined by economics and siting. The least costly means of discharging waste heat is
to dissipate it in large rivers, lakes, or the ocean (Foster & Wright Jr., 1977). Refer to
Appendix 4 for a description of other issues considered when siting nuclear power plants.

11

Nuclear power plants are located along the coast or near large inland bodies of water, and
thus need to be designed to withstand environmental impacts related to these sites.

1.1.2. External Events and the Design of Nuclear Power Plants
The primary goal in design of nuclear power plants is to maintain defense in
depth. The principle of defense in depth is implemented primarily by means of a series of
barriers which would in principle never be jeopardized. When properly applied, it
ensures that no single human or equipment failure would lead to harm to the public
(International Nuclear Safety Advisory Group, 1999).

In order to maintain defense in

depth, the design should prevent as far as practicable: challenges to the integrity of
physical barriers, failure of a barrier when challenged, and failure of a barrier as a
consequence of failure of another barrier. All levels of defense should be available at all
times, although some relaxations may be specified for the various operational modes
other than power operation (IAEA, 2003a).
The anticipated operational occurrence and design basis accident are used to
establish the structures and defenses necessary for proper design. The IAEA (2004)
defines the anticipated operational occurrence as an operational process deviating from
normal operation which is expected to occur at least once during the operating lifetime of
a facility but which, in view of appropriate design provisions, does not cause any
significant damage to items important to safety or lead to accident conditions. The
design basis accident is the accident conditions against which a nuclear power plant is
designed according to established design criteria, and for which the damage to the fuel
and the release of radioactive material are kept within authorized limits (IAEA, 2004).
The design basis accident includes the design basis flood and design basis external event.
During the site assessment data is gathered for the purpose of establishing the design
basis accident. The site hazard and the layout of the plant are used to determine the
design basis external event, while the flood hazard is utilized to determine the design
basis flood (IAEA, 2003a).
Data must also be collected to establish long-term removal of heat from the core
in the event of an accident. In addition to flood protection, the design should
accommodate the effects of temperature extremes, and the statistical analyses should

12

provide the necessary data in forms usable for such purposes. The persistence of very
high or very low temperatures is a factor that should be considered (IAEA, 2003d). For a
more complete coverage of how external events factor into design refer to Appendix 5.
Climate has always been an important factor in nuclear power plant operation.
First, suitable sites must provide a source of ample cooling water. Second, extreme
events must be considered in the establishment of design parameters. A certain amount
of climate variability can be accommodated in design and site selection. Climate change
leads to an increase in climate variability thereby making planning in design and
operation increasingly difficult. The next section explores the impacts of climate change
to nuclear power operation.

1.2. The Influence of Climate Change on Nuclear Power
Plants
The dependency of nuclear power on water dictates that reactors be located along
the coast or near large inland bodies of water, and this fact more than any other is crucial
to nuclear power’s vulnerability to climate change. It is also the reason why nuclear
power plant operation can impair the ability of human systems and ecosystems to adapt.
The aforementioned criteria elucidate the consequences of each of these climate problems
for coastal and inland reactors as shown in table 1 and 2 respectively.
Table 1. The consequences of climate impacts for coastal reactors.
Criteria

Climate Problem

Consequence

Interrupted

Storms and

Storms and flooding cause power

Operation

sea level rise

reductions and reactor shutdowns.

Financial Costs

Storms and

Revenue loss & costs incurred to

sea level rise

implement shoreline and flood protection.

Adaptation Impairment

Storms and

Coastal development reduces the

Human Systems

sea level rise

ability of human systems to adapt.

Adaptation Impairment

Storms and

Developed/engineered shorelines reduce

Natural Systems

sea level rise

the ability of coastal ecosystems to adapt.

Other Environmental

Storms and

Safety is impaired thereby increasing

Problems

sea level rise

the probability of an accident.

13

Table 2. The consequences of climate impacts for inland reactors.
Criteria

Climate Problem

Consequence

Interrupted

Drought, heat waves,

A lack of cooling water causes power

Operation

intake biofouling

reductions and reactor shutdowns.

Flooding

Flooding causes reactor shutdowns.

Financial Costs

Drought, heat waves,

Financial costs are incurred to implement

intake biofouling

dry cooling systems and to adjust intakes.

Adaptation Impairment

Drought

Human Systems

Demand for cooling water limits the ability
of regions to adapt to drought conditions.

Heat waves

Power outages reduce the ability of
populations to adapt to heat waves.

Adaptation Impairment

Drought and

Thermal releases reduce the ability of

Natural Systems

heat waves

aquatic systems to adapt.

Other Environmental

Flooding,

Safety is impaired thereby increasing the

Problems

intake biofouling

possibility of an accident.

Impacts of climate change to safe and continued operation of nuclear power
plants has been recognized by the International Atomic Energy Agency (IAEA); as a
result, they are currently creating guidance on adapting nuclear power plant design and
operation to climate change. The IAEA is an independent organization related to the
United Nations system that works to build and strengthen international safety and
security for nuclear operations by advising on international standards, codes, and guides;
binding international conventions; international peer reviews to evaluate national
operations, capabilities, and infrastructures; and an international system of emergency
preparedness and response (IAEA, 2008a). According to the IAEA (2003c), the major
hazards to nuclear power plants are changes in the following:
a) Temperatures of the air and the sea
b) The patterns, frequency and storminess of winds
c) The characteristics of precipitation such as higher peak levels
d) Rises and anomalies in sea levels
e) The flow rates of rivers
The most important consequence of the recognized effects of global warming is
the need for the continuous long term monitoring of environmental parameters. An
accurate estimation of such effects should be carried out in the site assessment phase
(IAEA, 2003c). The IAEA (2003c; 2006a) advises that some safety margin should be
taken into account in the design of a nuclear power plant and changes in natural hazards
may need to be considered at the time of Periodic Safety Reviews.

14

If the entire plant lifetime is considered, the following generally agreed estimated
variations in parameters may be considered: rise in mean sea level of 35-85 cm, rise in air
temperature 1.5-5˚C, rise in sea or river temperature 3˚C, increase in wind strength 510%, increase in precipitation 5-10% (IAEA, 2003c).
The IAEA proposes that immediate action to address climate change may not be
necessary; however, careful monitoring and site hazard evaluation for the lifetime of the
facility is of the utmost importance to ensure that action is taken when necessary (IAEA,
2003b, 2003c). Furthermore, land should be reserved in order to allow further
development of water defenses when deemed necessary in particular during the
construction of a new plant (IAEA, 2003c). An example of appropriate action was that of
a regulatory body in one Member State who sent a generic letter to all nuclear site
licensees in November 1997, stating that it expected safety submissions for new
construction projects plants and periodic safety reviews of existing facilities to take
account of the potential effects of climate change (IAEA, 2006a).
The potential for climate change to affect nuclear power plants can be inferred
from prior experience of extreme weather impacts on reactors. The IAEA has a database
containing 20 years of feedback from the operation of nuclear power plants. Only 3% of
reported events where degradation of plant safety occurred were due to external events
(IAEA, 2003b). However, external events have the highest percentage in serious
consequences often involving challenges to the defense in depth of the plant. Moreover,
the reporting categories of external events include the degradation of barriers,
identification of generic problem of safety, identification of design and construction,
potential safety significance, release of radioactive material or exposure (IAEA, 2003b).
The most serious consequences were recorded for low temperatures, high winds,
flooding, lightning, biological fouling, electromagnetic interference and earthquakes.
These either directly affected the plant or caused the degradation of safety features
through the unavailability of off-site power, the ultimate heat sink and evacuation and/or
access routes (IAEA, 2003b).
In such a situation, some new innovative reactor designs take advantage of
passive safety features provided within the protected reactor building or inner
containment, disregarding the availability of external sources of supply of electricity or
cooling water. Several designs provide for physical presence of large thermal capacity

15

heat sinks available to cool the reactor core without depending on availability of
externally powered pumps within the containment or elsewhere (IAEA, 2006a).
Monitoring and improved designs may ensure safe operation of nuclear power
plants. However, safe operator action during an extreme external event often requires
reactor shutdown.

Presently the costs to deal with external events are deemed to be on

the low end at 12-22% of total plant costs (IAEA, 2003b). Climate change could increase
these costs substantially. Climate change threatens the operation of nuclear power plants
in two important ways: direct damage of the power plant and reduced availability of
cooling water.

1.2.1. Flooding and Storm Damage
The safety of nuclear power plants can be seriously affected by flooding, both for
sites on rivers and for sites on the sea coast, or large lakes (IAEA, 2003c). Seawater level
is influenced by changes in average sea level induced by climate change, an increase in
storm surges coming from the open sea, wind waves, human made structures such as tide
breaks and jetties and for plants located in an estuary, and the river's discharge (IAEA,
2003d).
Flooding can have major bearing on the safety of the plant and may lead to a
postulated initiating event that is to be included in the plant safety analysis. A postulated
initiating event is an event identified during design as capable of leading to anticipated
operational occurrences or accident conditions (IAEA, 2002). The presence of water in
many areas of the plant may be a common cause of failure for safety related systems,
such as the emergency power supply systems or the electric switchyard, with the
associated possibility of losing the external connection to the electrical power grid, the
decay heat removal system and other vital systems. Unavailability of power can have a
significant adverse impact on a plant’s ability to achieve and maintain safe-shutdown
conditions (Eide et al., 2004). Water pressure on walls and foundations may challenge
their structural capacity. Deficiencies in the site drainage systems and in non-waterproof
structures may cause flooding of the site. A flood may also affect the communication and
transport networks around the plant site, which in itself could cause an emergency
(IAEA, 2003c). Flooding can contribute to the dispersion of radioactive material to the
environment in an accident. The dynamic effects of the water can cause damage to

16

structures and erosion at the site boundary. Moreover, debris of all types may be
transported by floods causing not only physical damage, but also damaging the water
drainage system and obstructing water intakes (IAEA, 2003c).

1.2.2. Availability of Cooling Water
Sea level rise along with increase in storms could potentially affect the
availability of cooling water due to biological fouling (IAEA, 2003c). Increased
temperatures can affect the species composition of algae. There should be provisions for
continuous biological monitoring of the ultimate heat sink to give early warning of
changes which might significantly affect its performance such as the introduction of new
strains of algae with different growth habits or greater tolerance to cooling water
conditions (IAEA, 1981, 2003a). However, clogging of intakes is not the only factor
limiting the availability of cooling water.
An important consideration related to plant siting along rivers concerns periods
of low stream flow. This consideration is particularly relevant for those plants which do
not use cooling ponds with a sufficiently large storage capacity to allow within-pond
recirculation of water for several days (Giusti & Meyer, 1977). Low flows threaten the
ability of the ultimate heat sink to perform adequately. During low-flow periods the
flow consists of groundwater discharge and evaporation is at a maximum; as a result, the
water has much higher mineral concentrations and may exceed standards for cooling
water (Giusti & Meyer, 1977). Ecological impact may occur on aquatic organisms
because of the reduced water flow, thermal pollution, or a combination of both.
Moreover, low-flow and extreme high temperatures often occur at the same time.
Water demands increase with temperatures. In particular, closed systems with
cooling ponds or canals need more water to cool the same amount of steam when ambient
temperature increases (Yang & Dziegielewski, 2007). Cool water is needed to operate
reactors safely, but efficiency will decrease before safety becomes a concern. The
efficiency of nuclear power plants depends on site with the most important factor being
water temperature (Australian Uranium Association, 2007). The lack of available
cooling water can force the shutdown of the plant, with costs and loss of revenue to the
plant operators and loss of service to consumers.
Climate change affects nuclear power in multiple ways. This thesis evaluates the

17

impacts of climate change to nuclear power operation and the consequences of nuclear
power to climate change adaptation. However, it is also necessary to explore other issues
that arise when electing to use nuclear power. The problems climate change poses to
nuclear power must be evaluated in the context of the nuclear choice and the costs
associated with that choice.

1.3. The Nuclear Choice
The adaptation problems related to any mitigation measure should be considered,
but nuclear power is of particular interest. Nuclear power has tremendous benefits.
When compared to coal nuclear power is capable of generating considerable amounts of
energy from a very small amount of fuel without harmful greenhouse gas emissions.
Compared to the renewable alternative sources of energy (e.g. photovoltaic, solar
thermal, wind, and geothermal), nuclear technology is a now-familiar way to make
electricity. It is a technology that is proven to be able to generate large amounts of
concentrated power, whereas alternative energy technologies have an extremely limited
history as proven practices. However, nuclear power is associated with considerable
costs and risks independent of climate impacts. The IPCC stated in the latest report that
nuclear power has the potential for an expanded role as a cost-effective mitigation option,
but the problems of potential reactor accidents, nuclear waste management and disposal
and nuclear weapon proliferation will still be constraining factors (Sims et al., 2007).
Concern regarding proliferation and waste has led to debate on whether to pursue
an open or closed fuel cycle. In an open fuel-cycle, once the fuel is used it is disposed of
as waste, while a closed-fuel cycle involves the utilization of spent fuel in another
reactor. Reprocessing of nuclear waste raises concerns over nuclear proliferation, since it
is difficult for reprocessing facilities to keep track of small amounts of plutonium. For
instance, a total of 70 kg of plutonium, enough for 10 nuclear weapons was unaccounted
for over a five year period in a Japanese reprocessing facility (Union of Concerned
Scientists, 2007). Moreover, an international research effort in advanced reprocessing
would itself spread expertise in the chemistry of radioactive elements, including
plutonium (Butler, 2004).
Nuclear proliferation is a concern regardless of whether open or closed fuel
cycles are chosen. 235U must be enriched to 90% to create a bomb and 2-5% to be used as

18

fuel in a nuclear reactor. Seemingly a large difference, but more work is required per
kilogram of 235U to enrich it from 0.7% to 5% than to carry it the rest of the way to 95%
enrichment; therefore, 3% enriched uranium fuel is more than “halfway” to 95%
enrichment (Bodansky, 2004). Pressurized heavy water reactors use less expensive
natural uranium; however, proliferation remains a concern because the continuous
refueling process in these reactors makes it difficult for international inspectors to
monitor (Energy Information Administration, 2007).
A MIT study looking at the future of nuclear power concluded that for the next
few decades, government and industry in the U.S. and elsewhere should give priority to
the deployment of the once-through fuel cycle, rather than the development of more
expensive closed fuel cycle technology involving reprocessing and new advanced thermal
or fast reactor technologies (MIT, 2003). The predominance of the once-through fuel
cycle will cause continued demand of new fuel from mines and increasing waste to store.
Commercial spent nuclear fuel is the major contributor to high level radioactive waste.
Taking into account worldwide projections of nuclear power growth, it is determined that
eventually a new repository of the capacity of the Yucca Mountain Repository will have
to be built somewhere in the world every three to four years. In U.S. alone it is estimated
that by 2100 the country will have accumulated more than 300 000 t of spent fuel;
however, the proposed Yucca Mountain Repository can receive only 70 000 t of waste
(IAEA, 2006b). The issue of waste-storage is more than an environmental issue, since
uncertainty about the cost of waste-storage continues to worry potential investors (Giles,
2006).
Paffenbarger (1998) cautioned that attaining publicly acceptable safety in plant
operation and spent fuel management could render nuclear power uneconomic in
comparison to other options. In addition to these financial concerns, the nuclear industry
has a history of delayed construction and cost overruns. In the United States between
1975 and 1989, the average period required to complete a plant increased from 5 years to
12 years. Consequently, many utilities collapsed due to construction debts (Aston et al.,
2006). The expectation is that standardized reactor design and streamlined licensing
processes will reduce the likelihood of cost overruns and delays. Nonetheless, two years
ago, the price of a 1,500 megawatt reactor was $2 billion to $3 billion, while presently
the cost is up to $7 billion due to the higher cost for concrete, steel, and labor (Carey et

19

al., 2008). In addition, construction of an Evolutionary Pressurized Water Reactor in
Finland is several years behind and approximately $2 billion over budget. Similarly,
construction of two Advanced Boiling Water Reactors in Taiwan is now five years
behind schedule. Their estimated cost has grown from $3.7 billion to between $7.4 and
$9.1 billion (Schlissel & Biewald, 2008). The building of new reactors is unlikely to
happen without significant support from the government. In the United States, federal
subsidies for nuclear power include a 1.8 cent tax credit for each kilowatt hour of
electricity produced, which could be worth more than $140 million per reactor per year.
Additionally, the federal government is providing $18.5 billion in loan guarantees, and a
payout of $500 million for each of the first two plants built if there are delays for reasons
outside company control (Carey et al., 2008).
In addition, research money is needed for expansion of nuclear power, since no
new reactors and fuel cycle technologies simultaneously overcome the problems of cost,
safety, waste and proliferation (Hoffert et al., 2002; MIT, 2003). For a description of
new reactor developments and research goals refer to Appendix 6. Research investment
in energy has varied greatly from country to country, but in most cases has declined
significantly in recent years since the levels achieved soon after the oil shocks during the
1970s (Sims et al., 2007). In the U.S. it is obvious that nuclear has historically won in the
competition for research dollars. Wind, solar, and nuclear power received approximately
$150 billion in cumulative federal subsidies over roughly fifty years with over 96%
supporting nuclear power (Goldberg, 2000). The assessment of adaptation problems
associated with nuclear power must be considered in the context of these problems. The
safety of nuclear power remains a concern in the public eye independent of climate
impacts. In addition, nuclear power requires considerable investment dollars independent
of the financial resources needed to adapt operations to climate change.
Policy-makers arrive at different conclusions on whether the risks, including
financial risks, of nuclear power are worth the benefit. Agreeing to disagree does not
give nuclear power the push it needs on a global scale. In order to make a significant
reduction in greenhouse gas emissions 1000 or more new reactors will need to be
deployed worldwide (MIT, 2003; Socolow et al., 2004). In addition, the mitigation
potential of nuclear power in both the short and long-term is under debate as discussed in
Appendix 7. Discussions regarding the sustainability of nuclear power have taken place

20

within the UN Commission on Sustainable Development (CSD), which in 2006 and 2007
focused on energy for sustainable development, industrial development, air
pollution/atmosphere and climate change. The IAEA (2007b) deems a decision by the
CSD that nuclear power is inconsistent with sustainable development as potentially a
significant constraint on the development of nuclear power. This is particularly true since
new international arrangements are needed for nuclear power to make a significant
reduction of greenhouse gas emissions (Socolow et al., 2004). However, leaders of 16
Asian nations including China and India signed a pact on the environment pledging
action on climate change in part through the cooperation in promoting and developing the
use of nuclear energy (Agence France Presse, 2007). In contrast, environment ministers
from Austria, Germany, Ireland, Italy, Latvia and Norway made a joint declaration that
nuclear energy and sustainable development are not compatible; furthermore, nuclear
energy is not an option to answer the challenge of climate change (BMU, 2007).
Nevertheless, nuclear power is currently an important source of electricity in
many countries. In 2006, 15.2 % of the world’s electricity needs were met by nuclear
power (IAEA, 2007a). As many of the existing nuclear power plants approach the end of
their operating life, new plant construction will be necessary to continue to meet this
proportion of the world’s electricity needs through nuclear. The demand for power plant
construction will be even greater if nuclear power becomes the preferred choice for
climate change mitigation. Clearly nuclear power has at once many risks and many
benefits. The impact of climate change on nuclear power operation might add enough risk
to shift the focus away from nuclear as a mitigation solution.

Part I Coastal Climate Impacts
This section evaluates the climate impacts at coastal nuclear power plants. The
first step in the evaluation is to review the challenges associated with the coastal
environment and how climate change will amplify these problems. In Chapter 2, a
literature review provides details on sea level rise, coastal storms, erosion, coastal
defenses, and the uncertainty in predicting climate change. The methods used to evaluate
nuclear power plant operation at coastal locations are explained in Chapter 3, while
Chapter 4 presents the results of the analysis.

21

2. Coastal Hazards Background
The abundance of cool water available at coastal locations makes them an
attractive site for nuclear power plants. However, coastal environments are stressful and
dynamic. Climate change impacts the coastal environment in a variety of ways that
interact. For instance, the intensity of coastal storms are predicted to increase due to
warmer ocean temperatures (K. Emanuel, 2005; K. A. Emanuel, 1987). Stronger storms
combined with sea level rise increase the risk of flooding. Furthermore, a rise in mean
sea level will increase flooding along the coast for four reasons: a higher sea level
provides a higher base for storm surges to build upon, erosion will increase the
vulnerability of oceanfront developments, higher water levels will reduce coastal
drainage and thus would increase flooding attributable to rainstorms, and a rise in sea
level will raise water tables (U.S. EPA, 1989).

2.1. Sea level Rise
On a global scale mean sea level has been rising. For the 20th century, the
average rate was 1.7 ± 0.5 mm/yr, while the average rate from 1961 to 2003 was 1.8 ±
0.5 mm/yr. There is high confidence that the rate of sea level rise has increased between
the mid-19th and the mid-20th centuries. Furthermore, there is evidence for an increase in
the occurrence of extreme high water worldwide related to storm surges, and variations in
regional climate (Bindoff et al., 2007). Satellite observations available since the early
1990s provide more accurate sea level data with nearly global coverage. This decadelong satellite altimetry data set shows that since 1993, sea level has been rising at a rate
of around 3 mm/yr, significantly higher than the average during the previous half century.
Coastal tide gauge measurements confirm this observation, but indicate that similar rates
have occurred in some earlier decades (Bindoff et al., 2007).
There are uncertainties in the estimates of the contributions to sea level change,
but understanding has significantly improved for recent periods. For the period 1961 to
2003, the average contribution of thermal expansion to sea level rise was 0.4 ± 0.1 mm/yr
(Bindoff et al., 2007). During recent years (1993–2003), for which the observing system
is much better, thermal expansion and melting of land ice each account for about half of
the observed sea level rise, although there is some uncertainty in the estimates. Thermal

22

expansion is projected to contribute more than half of the average rise, but land ice will
lose mass increasingly rapidly as the century progresses (Bindoff et al., 2007). Inability
to account for all the processes leads to one uncertainty in sea level rise projections.
Although simulated and observed sea level rise agree reasonably well for 1993 to 2003,
the observed rise for 1961 to 2003 is not satisfactorily explained, as the sum of
observationally estimated components is 0.7 ± 0.7 mm/yr less than the observed rate of
rise. This indicates a deficiency in current scientific understanding of sea level change
and may imply an underestimate in projections (G.A. Meehl et al., 2007).
The observational constraint on sea level rise projections is also weaker, because
records are shorter and subject to more uncertainty. As well, current scientific
understanding leaves poorly known uncertainties in the methods used to make projections
for land ice. The IPCC sea level rise projections are integrated with scenarios of CO2
concentration; yet, uncertainties in carbon cycle feedbacks are not included in the results.
The carbon cycle uncertainty in projections of temperature change cannot be translated
into sea level rise because thermal expansion is a major contributor and its relation to
temperature change is uncertain (G.A. Meehl et al., 2007).
Possible interactions between freshwater fluxes from ice sheets, ocean
circulation, and climate may also lead to unexpected changes in the melting of glaciers
(Alley et al., 2005). A local change in the density distribution through temperature and
salinity anomalies will alter the horizontal pressure gradients, and therefore will be
balanced by a change in circulation patterns. Large-scale circulation changes may
redistribute characteristic water masses, leading to different sea level changes regionally.
In the case of the Atlantic meriodonal overturning ciruculation (MOC), if the deep-water
formation rate was decreased or if the deep water formed became less dense, sea level
rise in the North Atlantic region would be expected to be stronger than the global average
(Landerer et al., 2007). Anomalies on an ever smaller scale may cause significant
concern. For instance, along the California coast high tide levels are rising faster than
mean sea level for reasons that are not understood (D. Cayan et al., 2006).
Changing mass of the great ice sheets of Greenland and Antarctica represents the
largest unknown in predictions of global sea level rise over the coming decades. The
flow of several large glaciers draining the Greenland Ice Sheet is accelerating. This
change, combined with increased melting, suggests that existing estimates of future sea

23

level rise are too low (Dowdeswell, 2006; Hansen et al., 2007). While the IPCC
acknowledges discharge of ice from the ice sheet has accelerated due to increased ice
flow in recent years, limited understanding of the relevant processes prohibits projections
of how much it would add to sea level rise (Bindoff et al., 2007). For instance, glacier
discharge to the sea has increased in recent years in both Greenland and the Antarctic as
warm water melts the floating ends of glaciers from below. This new evidence indicates
that ocean temperature plays a more critical role in determining how much glacial melt
contributes to changes in sea level than the warming atmosphere (Bindschadler, 2006).
Positive feedbacks in ice sheet collapse are also of concern. The lower albedo of the
exposed ice-free land causes a local climatic warming whereby melt water on the surface
might accelerate ice flow. A climate forcing that switches the abledo of a sufficient
portion of an ice sheet could be catastrophic. The unknown is how much human-made
climate forcing is needed to cause the albedo-flip mechanism on West Antarctica and/or
Greenland on a scale large enough to initiate multiple feedbacks and nonlinear ice sheet
collapse (Hansen et al., 2007)?
The IPCC concurred that ice shelf collapse due to surface melting is unlikely
during the 21st century, but expressed low confidence in the inference because of large
systematic uncertainty in the regional climate projections, and the uncertainty of episodic
surface melting (G.A. Meehl et al., 2007). Satellite and in situ observations of ice
streams behind disintegrating ice shelves highlight some rapid reactions of ice sheet
systems. This raises concern about the overall stability of the West Antarctic Ice Sheet,
the collapse of which would trigger another five to six meters of sea level rise (G.A.
Meehl et al., 2007).
Hansen et al. (2007) contend that existing ice sheet models are missing realistic
representation of the physics of ice streams and icequakes, processes that are needed to
obtain realistic nonlinear behavior. In the absence of realistic models, Hansen et al.
(2007) argue that it is better to rely on information from the Earth’s history which reveals
that large changes of sea level occur within century and shorter timescales. Regardless of
the potential for abrupt climate change, the IPCC scenarios might be overly conservative.
The rate of rise for the past 20 years of the reconstructed sea level is 25% faster than the
rate of rise in any 20-year period in the preceding 115 years (Rahmstorf et al., 2008).
Therefore, a rise of over 1 m by 2100 for strong warming scenarios cannot be ruled out,

24

because all that such a rise would require is that the linear relation of the rate of sea level
rise and temperature, which was found to be valid in the 20th century, remains valid in
the 21st century (Rahmstorf, 2007).
Uncertainty remains on the exact amount of future sea level rise. Nevertheless,
sea level is currently rising and will continue despite mitigation efforts. Sea level rise
alone is a problem that is perceived to have a long lead-time. The real problem is the
combination of storms and sea level rise: when flood levels exceed a design basis that
was determined decades ago. This holds true for any type of coastal defense structure.
Protective structures built to withstand past conditions can not withstand elevated water
levels in conjunction with storms (Leatherman & Kershaw, 2001).

2.2. Coastal Storms
The Pacific coast contends with storms primarily in the winter months. Higher
sea levels occur during autumn and winter due to seasonal wind patterns, and upwelling
along the California coast worsens the impact of storms (D. Cayan et al., 2006). In
addition, the tide remains near the maximum level for approximately two hours, and
during winter, higher-high water always occurs during very early morning hours, thereby
hindering preparations that must be carried out the night before the storm arrives (Flick &
Badan-Dangon, 1989).
The Atlantic has two storm seasons. Generally, most hurricanes occur from June
to September, with hurricane season officially ending in November, and northeasters
prevail from October to May (Farris, 2007; Zhang et al., 2000). Hurricanes and
nor’easters differ in the type of impact. Although hurricanes produce higher surges, they
have shorter duration and influence a relatively small length of coastline. While
nor’easters are typically lower-energy, they pose more of a threat to shoreline erosion,
since they occur more frequently, last longer, and cover larger areas (Frumhoff et al.,
2007; Pilkey Jr. et al., 1984; U.S. National Research Council, 1990; Zhang et al., 2000).
The major damage from hurricanes occur within 100 to 150 km of the landfall
position, except when torrential rains continue after a hurricane moves far inland, causing
extensive river flooding (Simpson & Riehl, 1981). Typically, the storm surge is the most
dangerous component of a coastal storm with historically disastrous coastal flooding
occurring when strong storm surge coincides with high tide (Pugh, 1987). A storm surge

25

is a sudden movement of water caused by a rise in sea level due to low barometric
pressure and high wind (Pugh, 1987). Water weighs approximately 1,700 pounds per
cubic yard, and currents created by the tide combine with the action of the waves to
severely erode beaches and coastal highways. Many buildings withstand hurricane force
winds until their foundations, undermined by erosion, are weakened and fail (National
Hurricane Center, 2008). The importance of storm surge is not just the simple flooding it
brings, but rather the elevation of still-water surfaces upon which waves may extend their
cascade of energy, erosive action, and battering for hundreds of meters- sometimes
kilometers - in-land from ocean and bay shores (Simpson & Riehl, 1981). Moreover,
wave energy increases with the square of the wave height. Thus, a 0.6 meter (2 foot)
wave would have 4 times the energy of a 0.3 meter (1 foot) wave. Small changes in water
level can cause significant changes in wave energy and the potential for shoreline damage
from wave forces (California Coastal Commission, 2001).
Bathymetry influences the height of the surge caused by a storm. A shallow slope
off the coast will allow a greater surge to inundate coastal communities. While areas with
a steeper continental shelf will not see as much surge inundation, large breaking waves
can still present major problems (National Hurricane Center, 2008). In a closed basin,
such as Chesapeake Bay, the effects of a surge can be increased because the water is
trapped at one end. The shallow depths throughout most of the Bay make its shores
susceptible to flooding during storm surges (Ward et al., 1999).
However, analysis of storm surges is not straightforward. During Hurricane
Eloise in 1975 a tidal maximum of 4.9 m (16 feet) was observed. Post analyses were
unable to account for more than a 2.8m (9.2 feet) rise caused by the storm surge, plus 0.7
m (2.3 feet) attributable to longer-term anomalies in sea level. The remaining 1.4 m (4.6
feet) is considered to have resulted from an unusual contribution from wave setup due to
the peculiar bathymetry. Here water depths average less than 3 m (9.8 feet) nearshore
and then drop rapidly to depths of more than 15 m (49.2 feet) in less than 1 km. The
evidence is that significant waves of about 10.5 m (34.4 feet) approached within several
kilometers of shore before breaking and cascading massive amounts of water shoreward
(Simpson & Riehl, 1981).
Coastal storms have dramatic impacts, but the occurrence of storms is highly
variable. The relationship between climate change and increased storm frequency and

26

intensity is difficult to establish due to muti-decadal oscillations. The El Niño Southern
Oscillation cycle (ENSO) is a natural coupled oscillator of the tropical Pacific Ocean and
atmosphere. The warm and cool episodes are phases of a self-sustaining cycle (Graham &
White, 1988). Sea level atmospheric pressures measured at Easter Island, representing
the South Pacific subtropical high, and Darwin, Australia, representing the Indonesian
equatorial low, oscillate in opposition and this phenomenon is termed the southern
oscillation. El Niño is preceded by strong trade winds and coincides with a relaxation of
the winds and is evident in the presence of excessively warm water off the coast of Peru
(Wyrtki et al., 1976).
Most of the major damage in coastal California over the past century has taken
place during El Niño years due to high tides, higher-than-normal sea level, and more
frequent and larger storm waves (Andrews et al., 2004; Griggs et al., 2005). During
certain intense ENSO periods, very large atmospheric lows develop north of the
Hawaiian Islands resulting in extremely long west-to east fetches and high winds. These
wind fields generate large amplitude, long-period waves out of the west that result in the
impacting of exceptional swell on the southern and central coasts of California (Seymour,
1996). These same storms pick up considerable moisture from the warm tropical waters
producing high rainfall causing coastal landslides and greatly accelerating cliff erosion
(Griggs et al., 2005). Sea surface temperature is also shown to be well correlated with
increases in large wave events, and while overall wave intensity has decreased in the last
20 years, the number of large wave events has increased (Seymour, 1996).
The pattern of steric sea level rise in the Pacific coincides with a tendency
towards more prolonged and stronger El Niños over this same period. Strong west to east
gradients in the Pacific have weakened, since it is now cooler in the western Pacific and
warmer in the eastern Pacific (Bindoff et al., 2007). The observed trend for more ENSO
events since 1976 has a probability of occurrence of once in every 1,100 years. Given the
unlikelihood of this trend, sustained El Niños conditions could be a consequence of
climate change (K. E. Trenberth & Hoar, 1996). Furthermore, the most recent period of
time with a climate warmer than today was during the early Pliocene when sea surface
temperature differences across the equatorial Pacific was similar to a modern El Niño
event (Wara et al., 2005).
Similar to ENSO, the occurrence of hurricane landfalls on the United States

27

might be related to alternating intervals of persistent above-average and below-average
surface temperature of the North Atlantic Ocean. The cycle of temperature variations,
known as the Atlantic Multidecadal Oscillation (AMO), has been identified by studying
records based on thermometer readings that date back to the late 1800s. The historical
record of major hurricane landfalls on the U.S. east coast from 1903 to 2000 shows that
landfalls are generally more common during warm phases of the AMO than they are
during cold phases (Poore et al., 2006).
The number of tropical cyclones and cyclone days as well as tropical cyclone
intensity has increased over the past 35 years in particular a large increase was seen in the
number and proportion of hurricanes reaching categories 4 and 5. The North Atlantic
shows a statistically significant increase since 1995. The increase in category 4 and 5
hurricanes has not been accompanied by an increase in the actual intensity of the most
intense hurricanes (Webster et al., 2005). However, models have linked increased
temperature with an increase in storm intensity (K. Emanuel, 2005; K. A. Emanuel,
1987). The potential intensity of tropical cyclones does not respond directly to seasurface temperature, but on the whole temperature profile of the troposphere. Potential
intensity of the storm increases much more because observed atmospheric temperature
does not keep pace with sea-surface temperature (K. Emanuel, 2005).
The 2005 North Atlantic hurricane season was the most active on record by
several measures, surpassing the very active season of 2004. Even before the peak in the
seasonal activity, the seven tropical storms in June and July were the most ever, and
hurricane Dennis was the strongest on record for the month of July and the earliest ever
fourth-named storm. The record 2005 North Atlantic hurricane season featured the largest
number of named storms. It had the largest number of hurricanes recorded, and is the
only time there have been four category 5 storms. Six of the eight most damaging storms
on record for the USA occurred from August 2004 to September 2005 (K. E. Trenberth et
al., 2007).
Nonetheless, until very recently the coastal environment has been relatively
calm; this is not the norm on a longer time scale. From 1965 to 1990, when the
populations of Florida and other southern states grew enormously, and nuclear power
plants were constructed to meet energy needs, only two major hurricanes (Gloria and
Hugo) struck the East Coast and none struck Florida (Neumann et al., 2000). Similarly,

28

in California, considerable coastal development took place between the mid-1940s and
the mid-1970s, a period characterized by below-average rainfall and storm frequency
(Griggs et al., 2005).
Proxy records provide evidence of climate further back in time. Corals and
marine sediment cores record vertical wind shear and sea surface temperature and these
records indicate that the average frequency of major hurricanes decreased gradually from
the 1760s until the early 1990s, reaching anomalously low values in the 1970s and 1980s.
The phase of enhanced hurricane activity since 1995 is not unusual compared to other
periods of high hurricane activity in the record (Nyberg et al., 2007).
While it is anticipated that the southern states must live with hurricanes, history
shows that the northeast can be devastated by hurricanes as well. The most intense
hurricane to strike the Northeast in recorded history was in 1938. The Great New
England Hurricane of 1938 made landfall in central Long Island, then moved north into
Connecticut, Massachusetts, and Vermont (Frumhoff et al., 2007). Sustained hurricane
winds occurred throughout most of southern New England and the eye of the storm was
observed in New Haven, Connecticut. Rainfall from the hurricane resulted in severe river
flooding across sections of Massachusetts and Connecticut. Storm tides were 4.3 m to
5.5 m (14 to 18 feet) across most of Connecticut and 5.5 m to 7.6 m (18 to 25 feet) from
New London east to Cape Cod (Vallee & Dion, 1998).
Along the California coast, the long-term variability of storminess can be
estimated from nearly continuous hourly tide gauge data from San Francisco (SFO) that
span from 1858 to 2000. Although heightened storminess has occurred during the last
two decades, the activity levels observed are not exceptional compared to earlier periods
such as the early 1900s and the late 1930s to early 1940s (Bromirski et al., 2003).
Moreover, tree ring data, ship logs, and insurance records for the past two centuries
clearly show that from the 1940s until the 1970s rainfall and high storm winds have been
far less critical than in most preceding periods. Ship logs describe storms with 15 m to 18
m (50 to 60 foot) waves and land subdivision plots on record show that entire city blocks
and streets along the coast have disappeared (Kuhn & Shepard, 1981, 1983). In
particular, the winters of 1884, 1886, 1889, 1890 and 1891 brought unusually severe
cyclonic sea storms to Southern California. The intense rainfall caused sediment
saturation of the bluffs, and a large storm swell coupled with high tides coincided with

29

river basin flooding (Kuhn & Shepard, 1981). Flooding in 1862 was so severe that all
coastal valleys and deltaic areas in southern California were inundated. High tides
prevented the runoff of flood waters for a considerable period (Kuhn & Shepard, 1981).
These historical storm events indicate that until recently nuclear power plants
have operated in a relatively calm coastal environment. An increase in storm frequency
or intensity has consequences to safe operation of nuclear power plants. In addition,
measures must be taken to protect coastal sites from storm damage and erosion.
Protecting shorelines come with additional financial costs and costs to the environment
that will be explored in the next section.

2.3. Shoreline Erosion and Coastal Defenses
Erosion of shorelines is most apparent during storm events. Sea level rise allows
energetic storm waves to attack higher elevations of the shoreline thus enabling erosion;
furthermore, high sea level has been found to exert a more significant impact on erosion
rates than changes in offshore wave conditions (Dickson et al., 2007; Leatherman, 2000;
Zhang et al., 2004). Sea level rise will cause the waters of the continental shelf to deepen
reducing bottom stresses, thereby enhancing wave generation (U.S. National Research
Council, 1987). Along open-ocean beaches, over 90% of the retreat due to sea level rise
is caused by erosion; the opposite is generally true for coastal marshes in sheltered bays,
lagoons, and estuaries with limited wave action (Leatherman, 2000). The primary reason
that sea level rise would induce beach erosion is that natural beach profiles are concave
upward; this geometry results in wave energy being dissipated in a smaller water volume
than without sea level rise, and thus the turbulence generated within surf zone is greater.
The profile responds by conforming to a more gentle nearshore slope, which requires a
redistribution of sand from the beach face to offshore (U.S. National Research Council,
1987; Zhang et al., 2004). The rate of erosion at any particular location is dependent on a
number of factors that include land use, sediment composition, and orientation of the
shoreline, bathymetry of the offshore region, and the local wind fetch for generation of
waves (Cronin et al., 2003).
High-energy and high impact events, from wave, tide and wind forces are
characterized by large spatial and temporal variability. As a result coastal landforms can
give the impression of robustness rather than sensitivity to environmental stresses over

30

the short-term (Pethick, 2001). Long-term changes to the energy environment can,
therefore, result in adjustments to coastal landforms that are not anticipated by coastal
users that tend to adopt a short-term variations as the norm (Pethick, 2001). For instance,
the cliffs of southern California and Chesapeake Bay experience sudden or episodic
erosion events. In southern California erosion was traditionally measured by placing nails
in cliffs. When the nails did not change over years or even decades it was concluded that
erosion was not a problem in the region. However, cliff retreat in this region occurs
suddenly during storms that bring heavy rains causing landslides of the cliff and
undercutting from wave action (Kuhn & Shepard, 1981, 1983). Failure or slumping
occurs when the material composing a bluff collapses due to gravity; as a result, the cliff
has a more gradual slope, which increases the bluff's stability. However, wave action
continues to remove material from the base of the bluff, which steepens the slope again,
decreasing stability. Consequently, coastal bluffs rarely attain stable slopes (Ward et al.,
1999). Steep cliff faces surrounding Chesapeake Bay have been known to collapse
catastrophically when they become saturated with water. Sandy soils above the clay
layer become saturated and the water seeps out causing soil particles to be removed just
above the clay layer. The overlying soil can collapse as this support is removed
(Mayrland DNR, 1999; Ward et al., 1999).
While some events might be catastrophic events, not all shoreline erosion is
detrimental. Dunes, beaches, and wetlands are critical habitats for a diverse array of
estuarine flora and fauna. Erosion delivers sediment that is critical to maintaining the
elevations of these habitats, particularly in response to sea level rise (Cronin et al., 2003).
Moreover, wave action also serves to transport sediments to beaches along the shore
thereby building beaches and buffering the cliffs against further erosion (Cronin et al.,
2003; Dickson et al., 2007; Maryland DNR, 2007).
Engineered measures to protect shorelines alter the sediment supply to local
beaches. Shoreline changes induced by variability of sediment supply can be much larger
than those resulting from sea level rise on some coasts (Zhang et al., 2004). In addition,
shore armoring reduces bluff erosion in the short term, but increases erosion of the beach
in front of the armored bluff due to wave reflection (Gutierrez et al., 2007).
Furthermore, coastal armoring hinders the ability of habitats and species to
migrate inland in response to rising sea levels leading to coastal squeeze and the loss of

31

valuable habitat (Glick & Clough, 2006; Neumann et al., 2000; Pethick, 2001). Adopting
a more dynamic viewpoint of coastal management ensures that coastal landforms remain
intact with a change in only their relative location (Pethick, 2001). One strategy for
planned retreat restricts coastal development thereby reducing the need for shore
armoring (Neumann et al., 2000). Long-term investments such as nuclear power plants
require shore armoring to operate in the coastal environment; therefore, these types of
developments prevent the implementation of the coastal retreat strategy.
Regardless of the environmental costs the demand for protection along developed
shorelines is likely and a necessary feature to protect nuclear power plants. The choice of
coastal structure for erosion mitigation depends on site-specific factors. Structures that
work satisfactorily in one location can be totally inadequate or detrimental in another
location (U.S. National Research Council, 1987). Sandy coastal shores are made of
natural units and must be treated as such. The effect of a structure on the remainder of
the shoreline must be analyzed before construction, and the plan must mitigate for
adverse effects. The direction and magnitude of sediment transport is the most uncertain
feature for coastal project plans, and site-specific data are difficult and expensive to
obtain (U.S. National Research Council, 1987). Moreover, sea level rise makes
predictions of sediment transport increasingly difficult. A change in depth alters the
propagation of tides and can alter the near-shore net transport thus changing the direction
of net sediment transport (Liu, 1997).
Several options are available to protect coastal developments including seawall,
revetments, jetties, and beach nourishment. Failure of defenses is always a possibility
particularly if the defenses are not heightened to accommodate sea level rise. While
extensive flooding results when the still-water level exceeds the top of the defense
structure, before this level is reached considerable flooding is likely to occur from
overtopping by waves (Pugh, 1987). Breakwaters, jetties, and seawalls will need to be
reinforced to withstand greater forces due to sea level rise. For seawalls, the foundation
will also be exposed to greater scour (California Coastal Commission, 2001). The cost of
a defense wall grows more rapidly than a simple linear increase with increases of design
height: the width of the footings must also be increased in proportion to the height, so
that in terms of material alone the increase is more closely proportional to the square of
the height (Pugh, 1987).

32

Estimates of the fixed construction costs for dikes or levees built to protect
against a one meter rise in sea level range from $150 to $800 per linear foot (1990
dollars). Corresponding cost estimates for sea wall and bulkhead construction range from
$150 to $4,000 per linear foot (1990 dollars) (Neumann et al., 2000). Beach nourishment
is generally favored over the construction of hard structures and may be necessary to
mitigate for the adverse impacts from shore armoring. However, beach nourishment is
costly at $2.6 million per mile in 1990 dollars (U.S. National Research Council, 1990).
Loss rates associated with beach nourishment are still only 30 percent due to the lack of
ability to forecast storms, and quantify wave and sediment conditions (U.S. National
Research Council, 1990). Erosion of a replenished beach will occur at a rate that it is at
least 10 times that of the natural beach; therefore, the beach must be repeatedly nourished
requiring long-term financial commitment (Pilkey Jr. et al., 1984; Pilkey et al., 1998).
Other drawbacks of replenishment projects include the unknown environmental impact of
replenished beaches to coastal flora and fauna and the lack of availability of sand (Pilkey
et al., 1998).
Adapting to the hazards of the coastal environment comes with financial and
ecological costs. For this reason, limiting coastal development and abandoning existing
developments remains an option for adapting to climate change. Adaptation of coastal
developments is particularly challenging because of the uncertainty regarding the exact
amount of sea level rise. Nevertheless, coastal sites have an aesthetic that attracts
development and in the case of nuclear power coastal sites provide much needed cooling
water. The next section discusses the methods used to model sea level rise and analyze
climate change impacts at coastal sites.

3. Coastal Methods
The analysis of climate impacts at coastal nuclear power plants focuses on plants
in the United States due to: the large fleet of nuclear power plants at coastal locations in
this country (both Atlantic and Pacific), the availability of elevation data, and relatively
easy access to reports on operational problems during storms. Adaptation to climate risks
can be viewed at three time-scales including responses to: current variability (which also
reflect learning from past adaptations to historical climates); observed medium and longterm trends in climate; and anticipatory planning in response to model-based scenarios of

33

long-term climate change (Adger et al., 2007). In this section these three different
approaches are used to evaluate nuclear power adaptation to the coastal environment.
First, future sea level rise and storms conditions are modeled using ArcGIS. Next, in
order to understand how nuclear power operations deal with current climate variability
the impacts of recent storm events are reviewed. Finally to determine if the necessary
anticipatory measures are being made current practices used to determine design
parameters for external events are evaluated.
These three approaches are necessary to evaluate the criteria outlined in Chapter
1. For instance, impairment to adaptation might not be immediately apparent, rather it is
a future problem revealed by sea level rise modeling and coastal vulnerability analysis.
However, direct impacts to operation can only be assessed by looking at operational
experience. Indicators are used to determine whether the criteria are met at the coastal
locations as shown in Table 3.
Table 3. Criteria and indicators used to evaluate nuclear power plants at coastal locations.
Criteria
Indicator
Interrupted Operation
Unplanned shutdowns, power reductions
Financial Costs
Flood protection, revenue loss
Adaptation Impairment - Human Systems
Adaptation Impairment - Natural Systems
Other Environmental Problems

Loss of adjacent lands
Loss of coastal habitat (coastal squeeze)
Safety problems that include:
Loss of off-site power
Communication failure
Restriction of evacuation routes
Equipment malfunction
Unplanned shutdowns

3.1. Sea Level Rise Methods
Inundation modeling and analysis of shoreline vulnerability was performed on
nuclear power plants currently operating within 2 miles of the Pacific and Atlantic
coastlines of the United States. Figure 1 shows locations of reactors examined in this
study.

34

Figure 1. Location of coastal reactors analyzed for vulnerability to sea level rise.

In reality sea level rise and coastal storms can impact reactors located farther
inland; however, difficulties in interpretation arise for sites located farther inland. For
instance, the model would show all elevations below sea level as flooded, even if a berm
is present that would block the flow of water. Sites that are located farther inland are
more likely to have topographical variation that would make interpretation of results
difficult. In this study only two reactors are a considerable distance from the shoreline:
Seabrook Station and Crystal River are 2 miles from the shore, but each site has a gentle
slope that permits the use of this type of model. Including these reactors in the study
provides valuable information because one potential adaptation strategy is to locate
reactors farther inland. This involves extra costs in constructing longer intakes, so it is
worthwhile to see whether this will ensure the sites are not flooded during storms.
The exact amount of sea level rise that is going to impact each of the sites is not
certain; therefore, it is necessary to develop scenarios. Time scenarios and the
corresponding rise in sea level were based on the work of the International Atomic
Energy Agency (IAEA) and the Intergovernmental Panel on Climate Change (IPCC)

35

respectively. The IAEA’s report, Flood Hazard for Nuclear Power Plants on Coastal and
River Sites recommends utilizing the results of investigations by the IPCC to assess the
effect of climate change on nuclear power plants; in addition, to account for uncertainty,
the upper bound of the 95% confidence interval should be used. The lifetime of a nuclear
power plant, including decommissioning time, can be taken to be 100 years, but it should
be possible to take measures to prolong this as far as necessary (IAEA, 2003c).
Considering the entire plant lifetime an agreed upon estimate for increase in mean sea
level ranges from 35-85 cm; in addition, the IAEA advises that land subsidence should be
considered along with climatic changes.
Four different time ranges (base year 2008) were considered in evaluating sea
level rise including: 1) the end of reactor operation, 2) the end of reactor lifetime, 3) 100
years, and 4) 150 years as shown in Table 4.
Table 4. Description of time-frames used in sea level rise modeling.
Time-frames
Description
End of Reactor Operation
Determined by years remaining in operating license.
End of Reactor Lifetime
100 years from when reactor began operating.
100 years in the future (2108) Assuming new reactor construction begins today.
150 years in the future (2158) New reactor construction within the next 50 years.

The years remaining in operation for each reactor were determined by the license
expiration date. Pilgrim Station is currently in the application process for a license
extension and therefore two reactor operation scenarios were determined: one based on
the current license and a second based on the license extension. Reactor lifetime was
determined by subtracting the years in operation from 100 as recommended by the IAEA.
Construction time was not included in calculating the reactors lifetime because of
extended construction periods at several of the reactors included in the study. In order to
determine the appropriateness of these sites for new reactor construction sea level rise
was modeled for 100 years in the future (assuming new reactor construction begins
today) and a time-frame of 150 years to take into account future construction.
The four time-frames were used to generate sea level rise scenarios as described in Table
5.

36

Table 5. Scenario description and corresponding quantity of sea level rise for California and
Florida, and the Northeast region.
Scenario

Description/Rationale

CA/FL

Northeast

End of Operation/

Global average of sea-level rise

3 mm/yr

4.3 mm/yr

Life of Reactor

since 1993

100 year low

Upper limit of low IPCC emission scenario

0.39 m

0.51 m

100 year mid

Upper limit of high IPCC emission scenario

0.59 m

0.72 m

100 year high

Estimate suggested in IAEA report

0.85 m

0.85 m

1m

Possible by end of century if linear trend continues

1m

1m

150 year low

Low 100 + 50 x (3.9 mm/yr) or (4.3 mm/yr)

0.59 m

0.72 m

150 year high

Mid 100 + 50 x (9.7 mm/yr)

1.21 m

1.21 m

Aside from land subsidence in the mid to north Atlantic region all locations have
sea level rise rates approximately equal to the global average. The current rate of sea
level rise of 3 mm/yr was assumed to remain constant for reactor operation and the total
life of the reactor. The average rate of subsidence is 1.3 mm/yr for Atlantic sites outside
of Florida (Frumhoff et al., 2007; Maryland DNR, 2007; Neumann et al., 2000).
Therefore, the lowest sea level rise scenario for Seabrook, Pilgrim, Millstone, and Calvert
Cliffs included the rate of subsidence at 4.3 mm/yr (3 mm/yr + 1.3 mm/yr). The various
100 to 150 year scenarios are based on scenarios developed by the IPCC. The 100 year
low scenario is 0.39 m, equivalent to the upper limit of the lowest IPCC emission
scenario, while the mid-scenario is 0.59 m, the upper bound of the high emission scenario
(G.A. Meehl et al., 2007). These are global averages, so for sites in the northeast an
additional 1.3 mm/yr is added to account for land subsidence. These 100-year scenarios
arrive at figures that are less than 0.85 m, the upper limit recommended in the IAEA
report; therefore, this amount was included as the 100 year high scenario. In addition, 1
m sea level rise was modeled for all sites because this amount of sea level rise by the end
of the century can not be ruled out (Rahmstorf, 2007). The low 150 year corresponds to
the upper limit for the lowest emission scenario developed by the IPCC. This scenario
uses the low 100 scenario for the first 100 years, and projects the next 50 years to have a
rate of sea level rise of 3.9 mm/yr. This is lower than the current trend for sea level rise
for sites experiencing land subsidence; therefore, 4.3 mm/yr was held constant for the
next 50 years under the low emission scenario. The high 150 year scenario used the mid100 year scenario for the first 100 years, and for the next 50 years a rate of 9.7 mm/yr
corresponding to the highest IPCC emission scenario. The 100 year mid scenario and

37

150 year low scenario have equivalent amounts of sea level rise.
Just looking at change in mean sea level is not sufficient in analyzing the impact
of sea level rise. Societal impacts of sea level change occur via the extreme levels,
mainly in the form of storm surges generated by tropical or extra tropical cyclones, rather
than as a direct consequence of mean sea level changes (Bindoff et al., 2007). In the case
of nuclear reactor operation, the rate of sea level rise is slow enough that defenses can be
maintained to protect the day to day operations. The real problem is during storms when
suddenly flood levels are higher than they were in decades past; therefore, storm
scenarios were included in the analysis. As a baseline the extent of flooding currently
experienced during storms was modeled. Next surge heights for specific storms and
hurricane categories were added to the projected rise in sea level. The effect of El Niño,
storm surges, and wave induced surges were modeled for sites in California. In
California, low pressure fronts change air pressure and can cause a short, one or two day
long increase in water elevation, while El Niños can lower atmospheric pressure for many
months increasing sea level by as much as 0.3 m (California Coastal Commission, 2001).
Storm surge along the California coast, excluding the effect of waves, rarely exceeds 0.7
m in amplitude. However, a wave induced surge on a beach, depending on breaker
height, can reach 1.5 m or more (D. R. Cayan et al., 2008). Along the east coast surges
created from nor’easters and hurricanes were modeled. Nor’easters or winter storms are
common at all sites on the east coast and often have a storm surge greater than 0.6 m
(Coastal Zone Management, 2007). The storm surges associated with the Saffir-Simpson
Hurricane Scale was utilized for the east coast as shown in Table 6. The height of surge
associated with a particular hurricane category is given as a range. For the model, the
low and high values of the Category I and Category IV were modeled, while the highest
value in the range was used for the Category II and Category III storms.
Table 6. The Saffir-Simpson Hurricane Scale (National Weather Service, 2007).

Category
I
II
III
IV
V

Wind speed
119-153 km/hr (74-95 mph)
154-177 km/hr (96-110 mph)
178-209 km/hr (111-130 mph)
210-249 km/hr (131-155 mph)
> 249 km/hr (>155 mph)

Storm surge
1.2-1.5 m (4-5 ft)
1.8-2.4 m (6-8 ft)
2.7-3.7 m (9-12 ft)
4.0-5.5 m (13-18 ft)
>5.5 m (>18 ft)

In addition, climate models have shown the potential for more intense storms due

38

to climate change (K. Emanuel, 2005; K. A. Emanuel, 1987; Poore et al., 2006);
therefore, areas currently experiencing hurricanes lower on the scale were modeled with a
one step increase. For instance, during Hurricane Isabel the storm surge that impacted
Maryland was equivalent to a Category II hurricane, so a Category III storm was modeled
for the site (Hennessee & Halka, 2003). The sites of Millstone, Pilgrim Station, and
Seabrook were impacted by a Category III storm in 1938; therefore, a Category IV
hurricane was modeled (Frumhoff et al., 2007). While historical evidence shows that
California has experienced greater storms than those of recent history, a reliable way of
predicting increased storms in California was not available.
Once the sea level rise scenarios were established, the conditions were modeled
using ArcGIS version 9.2. Coordinates for the reactors, presented in Table 7, were
available through various sources including the Virtual Nuclear Tourist (Gonyeau, 2007)
and were easily verified from the satellite imagery.
Table 7. Coordinates for reactors included in sea level rise analysis.
Nuclear Power Plant State
N
W
Seabrook
NH
42.898 -70.851
Pilgrim
MA
41.944 -70.577
Milstone
CT
41.312 -72.169
Calvert Cliffs
MD
38.435 -76.432
Saint Lucie
FL
27.348 -80.246
Turkey Point
FL
25.434 -80.329
Crystal River
FL
28.962 -82.697
San Onofre
CA
33.369 -117.557
Diablo Canyon
CA
35.211 -120.855

The USGS Digital Elevation Models (DEM) corresponding to the reactor
locations were downloaded from GeoCommunity in Spatial Data Transfer Standard
(SDTS) format (GeoCommunity, 2008). The SDTS conversion tool in Arc Toolbox was
used to convert the Digital Elevation Model (DEM) from SDTS format to raster. The
DEM was then projected onto satellite imagery for each reactor site. The satellite imagery
is available through Environmental Systems Research Institute (ESRI) and is created
from a variety of data sources including the U.S. Geological Survey (USGS) imagery for
metropolitan areas, and the best available U.S. Department of Agriculture data through
the National Agriculture Imagery Program, enhanced versions of USGS Digital
Orthophoto Quarter Quadrangle, and imagery assembled by ESRI through the ArcGIS
Online Content Sharing Program (ESRI, 2007).

39

The DEM was also used as the input layer for the raster calculator in spatial
analyst. The raster calculator created a shapefile that covered elevations equivalent to a
given rise in sea level. Analysis of elevation data to quantify land inundated due to sealevel rise is a commonly used method (Bales et al., 2007; Johnson et al., 2006; Michael,
2006; Neumann et al., 2000; Titus & Richman, 2001). ArcGIS allows one to develop
clear visualizations of inundation from available elevation data.
The digital elevation model data consist of a sampled array of regularly spaced
elevation values. These values are referenced horizontally to the North American Datum
of 1927 and vertically to the National Geodetic Vertical Datum of 1929 (NGVD 1929).
The NGVD 1929 was determined by holding mean sea level constant at the sites of 26
tide gauges, 21 in the U.S.A. and 5 in Canada. The reference plane in all other locations
was based on a leveling technique, thus the datum was not mean sea level, the geoid, or
any other equipotential surface (National Geodetic Survey, 1986).
The digital elevation models pose several problems during analysis. Because a
leveling technique was used, NGVD 1929 was not sea level in areas where water levels
diverge from the ideal plane even in 1929. Furthermore, Titus and Richman (2001) have
determined that rising sea level and subsidence have caused sea level and NGVD to
diverge 10 to 20 cm in most areas. Thus the elevation models are not an accurate
reflection of how far the land is above sea level. Although the raster calculator was used
to create a shapefile that covered the area at an elevation of 0 m at each site, and the
resulting shapefiles followed the coastline at each site, these models should not be used
for planning purposes. This model limits the ability to delineate between tides and storm
generated waves because mean sea level is unknown. Moreover, several of the digital
elevation models used in the study have low resolutions as shown in Table 8. Seabrook,
Pilgrim, Millstone, and Crystal River have vertical resolutions of only 1 m limiting the
sea level rise scenarios that could be examined. In addition, a 30 m horizontal resolution
does not accurately capture the change in elevation at sites where elevation can change
quickly over a short distance such as Calvert Cliffs.

40

Table 8. Resolution of Digital Elevation Models.
Site Name
State
X Resolution Y Resolution Z Resolution
Seabrook
New Hampshire
30 m
30 m
1.0 m
Pilgrim Station Massachusetts
30 m
30 m
1.0 m
Millstone
Connecticut
30 m
30 m
1.0 m
Calvert Cliffs Maryland
30 m
30 m
0.1 m
St. Lucie
Florida
10 m
10 m
0.1 m
Turkey Point Florida
10 m
10 m
0.1 m
Crystal River Florida
30 m
30 m
1.0 m
Diablo Canyon California
10 m
10 m
0.1 m
San Onofre
California
10 m
10 m
0.1 m

Results are summarized in tables for each reactor site. Table 9 provides an
example (portion) of a results table. The numbers in each cell represent the amount of
sea level rise in meters. The top row is sea level rise alone and each subsequent row
contains increasingly intense storm conditions, while the columns are successive timescenarios. This particular reactor has 35 years until end of operation and 75 years until
the end of reactor life. The rate of sea level rise is 3 mm/yr. The amount of sea level rise
until the end of operation is determined by:
(3 mm/yr × 35 yrs) ÷ 1000 mm = 0.1 m. The amount of sea level rise at the end of reactor
life is determined by: (3mm/yr × 75 yrs) ÷ 1000 mm = 0.2 m. The amount of sea level
rise during the life of the reactor surrounded in a bold border is 0.2 m this is added to the
1.2 m during a Category I hurricane to reach a total of 1.4 m for sea level rise at the end
of the reactor lifetime combined with a Category I hurricane.
Colors indicate the level of flooding. In those elevation models with only 1 m
resolution the cells are colored grey to indicate that the level of flooding can not be
determined by the model. “Potential for Flooding” is when the site first appears to start
flooding according to model results, but the flood waters have not reached structures on
the site, or covered the roads. “Considerable Flooding” describes conditions that cause
flood waters to reach structures on the site or block roads to the site. The red color code,
“Site Inundated” indicates that the entire site is covered in flood waters. The scenarios
generated here are also compared to the Design Basis Flood levels for each of the sites
that are available from U.S. NRC reports.

41

Table 9. Example of sea level rise results table. Values for sea level rise are in meters.
No Flooding

Potential For Flooding

Considerable Flooding

Site Inundated

Scenarios
Conditions

Current Storms

Sea Level Rise

End of Operation

Life of Reactor

Low 100

0.1

0.2

0.4

Northeastern

0.6

0.7

0.8

1.0

Category I Low

1.2

1.3

1.4

1.6

Category I High

1.5

1.6

1.7

1.9

Category II

2.4

2.5

2.6

2.8

Category III

3.7

3.8

3.9

4.1

Category IV Low

4

4.1

4.2

4.4

Category IV High

5.5

5.6

5.7

5.9

Category V

6.1

6.2

6.3

6.5

One limitation of this method is that elevation alone can not determine the
location of a future shoreline after sea level rises. Erosion, in addition to inundation, is a
concern and therefore a measure of the vulnerability of the coastline supplements this
model.
Coastal vulnerability is difficult to quantify; however, data on vulnerability of
shorelines throughout the U.S. coastline is available through a national assessment
conducted by the U.S. Geological Survey (Thieler & Hammar-Klose, 1999a, 1999b,
2000). This is the most thorough study of coastal vulnerability in the U.S. The methods
used in the data collection provide an index of the relative vulnerability of different
shoreline segments to sea level rise based on coastal geomorphology, rate of sea level
rise, past shoreline evolution, and coastal slope. The coastal vulnerability model used the
rate of sea level rise for the past 50-100 years, and therefore has different results
compared to the inundation model that considered the rate of sea level rise in the past
decade only. Looking at these variables identifies those portions of the U.S. coastal
regions the most at risk and the nature of that risk. Each coastal segment receives an
overall ranking of risk: low, moderate, high, or very high. In order to develop the
database Thieler and Hammar-Klose (1999, 2000) gathered relevant data from local, state
and federal agencies, as well as academic institutions. Refer to Appendix 8 for a

42

description of methods used by Thieler and Hammar-Klose.
The Coastal Vulnerability Index is a relative measurement of risk. The strength
of this method is in the details, as they shed light on risks other than inundation. For
instance, erosion rates are included in the analysis and the geomorphology variable
expresses the relative erosion rates of different landform types. Inundation modeling
reveals whether on-site flooding will occur, and if evacuation routes or site access will be
affected indicating safety concerns and the need to invest in flood protection. The Coastal
Vulnerability Index reveals the potential land lost due to erosion and sea level rise
indicating impairment in the ability of natural and human systems to adapt.

3.2. Literature Review of Nuclear Operations at Coastal
Sites
The next two sections of the coastal impacts analysis entail a literature review.
The primary source of literature comes from documents generated by the U.S. NRC
available through Agency wide Documents Access and Management System (ADAMS).
This information system provides access to all image and text documents that the U.S.
NRC has made public since November 1, 1999 and bibliographic records that the NRC
made public before November 1999. These reports are reviewed for indicators of safety
problems. Utility reports and industry journals provide additional information such as
length of reactor shut-down and revenue losses.
The first section evaluates the vulnerability of nuclear power plants to climate
change by reviewing problems encountered during past storms. Hurricanes can impact
reactors much further inland; therefore, the impact hurricanes have had on reactors
located in New Jersey, Pennsylvania, North Carolina, Virginia, Mississippi, Louisiana,
and Texas are included in this part of the analysis. The purpose is to not only review
impacts, but to look for evidence of adaptation and determine areas that continue to be
vulnerable. The second section provides a review of how external events are currently
incorporated in design of reactors located close to the coast. This is important to
understand whether anticipatory measures are being taken, such as consideration of
increases in precipitation, wind intensity, and sea level rise in design basis flood
estimates.

43

4. Coastal Results
The coastal environment provides an ideal location for nuclear power plants, in
terms of availability of cooling water; however, it is a challenging environment worsened
by storms and sea level rise due to climate change. Section 4.1 contains results of
inundation modeling and relative coastal vulnerability of each U.S. coastal reactor within
2 miles of the Atlantic and Pacific. The design basis flood levels for each reactor,
available through the U.S. NRC, are compared to the scenarios generated in this study.
The order of reactors analyzed in this section progresses from the most severe site
flooding to those sites with the least amount of flooding.
The results described in Section 4.2 reveal that past hurricanes have provided
vital learning opportunities, in that procedural changes have allowed for some adaptation
to hurricane conditions. Still, specific areas remain a challenge to safety. Finally, in
Section 4.3 the models used to generate probable storm conditions were found to give
disparate results; moreover, the models that gave appreciably lower surge levels were
adopted for use by the U.S. NRC.

4.1. Sea Level Rise Model Results
4.1.1. St. Lucie
The second reactor on the St. Lucie site began operation in 1983 and the
operating license expires in 2043. St. Lucie has 35 years remaining in operation and the
total life of the reactor was determined to be 75 years. St. Lucie is located on Hutchinson
Island south of Fort Pierce Inlet in St. Lucie County, Florida. Hutchinson Island is the
northern most barrier island on the east coast of Florida. Figure 2 provides a view of the
site with the digital elevation model used in the study.
For the St. Lucie site, the probable maximum hurricane (PMH) causes a probable
maximum surge elevation of 5.2 m (17.2 feet) above mean low water (MLW), and is the
basis for the probable maximum flood. The plant grade level is 5.8 m (19 feet) above
MLW. Additional measures to protect the plant are used such as reinforced concrete
flood walls and building entrances elevated to 5.94 m (19.5 feet). Some important safetyrelated systems and components have additional protection such as an elevation of 6.71 m
(22 feet) above MLW (Haney, 2006).

44

Figure 2. Satellite imagery of St. Lucie with Digital Elevation Model overlay.

45

Table 10. Sea level rise scenarios and results for St. Lucie.
No Flooding

Considerable Flooding

Site Inundated

Scenarios
Conditions

Current
Storm

End of
Operation

Life of
Reactor

100 Years
Low

100 Years Mid/150
Years Low

100 Years
High

Sea Level
Rise 1 m

150 Years
High

0.1

0.2

0.4

0.6

0.9

1.0

1.1

Northeastern

0.6

0.7

0.8

1.0

1.2

1.5

1.6

1.7

Category I Low

1.2

1.3

1.4

1.6

1.8

2.1

2.2

2.3

Category I High

1.5

1.6

1.7

1.9

2.1

2.4

2.5

2.6

Category II

2.4

2.5

2.6

2.8

3.0

3.3

3.4

3.5

Category III

3.7

3.8

3.9

4.1

4.3

4.6

4.7

4.8

Category IV Low

4

4.1

4.2

4.4

4.6

4.9

5.0

5.1

Category IV High

5.5

5.6

5.7

5.9

6.1

6.4

6.5

6.6

Category V

6.1

6.2

6.3

6.5

6.7

7.0

7.1

7.2

Sea Level Rise

The site potentially begins flooding at 0.3 m with some flooding of roads at this stage, while considerable flooding of roads begins
at 0.4 m as shown in Figure 3. A substantial amount of the site is flooded at 0.6 m, and the site is completely flooded at 0.7 m as shown in
Table 10 and Figure 4. The site experiences considerable flooding under current storm conditions and high intensity hurricanes would
cause flooding that approaches design limits within the life of the reactor. As shown in Table 11 the site receives a very high and high
coastal vulnerability index (CVI) ranking for the coast and river side respectively.

Table 11. Relative vulnerability of each of the coastal variables and overall vulnerability of the coastline at St. Lucie.
Reactor
Tide
Waves
Erosion Sea Level Rise Geomorphology
Slope
CVI
Saint Lucie (coast) Very High
High
Moderate
Low
Very High
Very High Very High
Saint Lucie (river)
Very High
High
Moderate
Low
Moderate
Very High
High

46

Figure 3. St. Lucie with a sea level rise of 0.3 m and 0.4 m.

47

Figure 4. St. Lucie with a sea level rise of 0.6 m and 0.7 m.

48

4.1.2. Crystal River
Crystal River unit 3 began operation in 1977 and the license expires in 2016.
The reactor has 8 years remaining in the operating license and the total life of the reactor
remaining was determined to be 69 years. Construction of a new reactor adjacent to this
site has been proposed. The Crystal River plant is located on Florida’s west coast
approximately 1 mile from the Gulf of Mexico in Citrus County, Florida. Figure 5
provides a view of the site superimposed with the digital elevation model used in the
study.
For Crystal River 3, the PMH results in a probable maximum surge elevation of
10.2 m (33.4 feet) above mean low water (MLW). The plant grade level is 9.3 m (30.5
feet) above MLW. Buildings housing class 1 components have been designed to
withstand a surge of water of 12.5 m (41 feet) above MLW which also accounts for wave
action and run-up. Therefore, the systems and components inside these buildings are
protected from the effects of external flooding by the use of retaining walls, steel and
concrete barriers, watertight equipment hatches, and watertight walls and doors.
Additional specific provisions for flood protection include administrative procedures;
such as, installation of dewatering pumps to control leakage through doors and walls.
MLW is the zero reference height for the site as measured at the Crystal River plant
intake canal at the Gulf of Mexico (Haney, 2006).

49

Figure 5. Satellite imagery of Crystal River with Digital Elevation Model overlay.

50

Table 12. Sea level rise scenarios and results for Crystal River.
Model Cannot Determine

Considerable Flooding

Site Inundated

Scenarios
Conditions

Current
Storms

Sea Level Rise

End of
Operation

Life of
Reactor

100 Years
Low

100 Years Mid/150
Years Low

100 Years
High

Sea Level Rise
1m

150 Years
High

0.02

0.21

0.38

0.59

0.85

1.00

1.09

Category I Low

1.2

1.22

1.41

1.58

1.79

2.05

2.20

2.29

Category I High

1.5

1.52

1.71

1.88

2.09

2.35

2.50

2.59

Category II

2.4

2.42

2.61

2.78

2.99

3.25

3.40

3.49

Category III

3.7

3.72

3.91

4.08

4.29

4.55

4.70

4.79

Category IV Low

4

4.02

4.21

4.38

4.59

4.85

5.00

5.09

Category IV High

5.5

5.52

5.71

5.88

6.09

6.35

6.50

6.59

Category V

6.1

6.12

6.31

6.48

6.69

6.95

7.10

7.19

The digital elevation model for Crystal River has a 1 m vertical resolution; therefore, flooding can not be determined for sea level
rise scenarios below 1 m as shown in Table 12. The site has considerable flooding with 1 m sea level rise and the entire site is covered
with a 2 m increase in sea level as evident in Figure 6. However, the design basis flood level (12.5 m) for this site is higher than all
scenarios generated here. The Crystal River site ranked moderate in the coastal vulnerability index (CVI) as shown in Table 13.

Table 13. Relative vulnerability of each of the coastal variables and overall vulnerability of the coastline at Crystal River.
Reactor
Tide
Waves
Erosion Sea Level Rise Geomorphology
Slope
CVI
Crystal River
Very High Very Low
Low
Very High
Low
Very High Moderate

51

Figure 6. Crystal River with a sea level rise of 1 m and 2 m.

52

4.1.3. Turkey Point
Turkey Point Reactor-4 began operation in 1973 and the license expires in 2033.
Turkey Point has 25 years remaining in operation and the total life of the reactor was
determined to be 65 years. The Turkey Point units are located on the west shore of
Biscayne Bay in Miami-Dade County, Florida. A new reactor has been proposed for this
site. Figure 7 provides a view of the site superimposed with the digital elevation model
used in the study.
For Turkey Point, the probable maximum hurricane results in a probable
maximum surge elevation of 5.6 m (18.3 feet) above mean low water (MLW). The plant
grade level is 5.49 m (18 feet) above MLW, and has been flood protected to an elevation
of 6.1 m (20 feet) above MLW. Components vital to safety, with the exception of the
intake cooling water (ICW) pumps, are protected against flood tides, and wave runup, to
6.7 m (22 feet) above MLW on the east side of the units by a continuous barrier
consisting of building exterior walls and stop logs for the door openings. Additional
protection against flooding is provided by placing safety equipment on pedestals or
providing curbs, use of closed doors with water-tight sills, floor drainage systems with
sumps and sump pumps, and water level alarms (Haney, 2006).

53

Figure 7. Satellite imagery of Turkey Point with Digital Elevation Model overlay.

54

Table 14. Sea level rise scenarios and results for Turkey Point.
No Flooding

Potential For Flooding

Considerable Flooding

Site Inundated

Scenarios
Conditions

Current
Storms

End of
Operation

Life of
Reactor

100 Years
Low

100 Years Mid
/150 Years Low

100 Years
High

Sea Level
Rise 1 m

150 Years
High

0.1

0.2

0.4

0.6

0.9

1.0

1.1

Northeastern

0.6

0.7

0.8

1.0

1.2

1.5

1.6

1.7

Category I Low

1.2

1.3

1.4

1.6

1.8

2.1

2.2

2.3

Category I High

1.5

1.6

1.7

1.9

2.1

2.4

2.5

2.6

Category II

2.4

2.5

2.6

2.8

3.0

3.3

3.4

3.5

Category III

Sea Level Rise

3.7

3.8

3.9

4.1

4.3

4.6

4.7

4.8

Category IV Low

4

4.1

4.2

4.4

4.6

4.9

5.0

5.1

Category IV High

5.5

5.6

5.7

5.9

6.1

6.4

6.5

6.6

Category V

6.1

6.2

6.3

6.5

6.7

7.0

7.1

7.2

Considerable flooding occurs at the site under current storm conditions as shown in Table 14. The potential for flooding occurs at
0.4 m and flooding becomes evident with a 0.5 m rise in sea level as shown in Figure 8. This level of sea level rise is somewhere between
the low 100 and mid 100 year scenarios. Roads could potentially flood at 0.7 m, and are completely covered at 0.9 m as seen in Figure 9.
As revealed in Figure 10 the site is almost completely flooded at 2.5 m. According to these scenarios, a Category V storm would cause
flooding conditions that exceed the probable maximum surge (5.6 m) for the site and approach the design basis flood level (6.1-6.7 m)
within the lifetime of the reactor. The Turkey Point site receives an overall coastal vulnerability index (CVI) ranking of high due to very
high rankings received in geomorphology, slope, and tides as shown in Table 15.

Table 15. Relative vulnerability of each of the coastal variables and overall vulnerability of the coastline at Turkey Point.
Reactor
Tide
Waves
Erosion Sea Level Rise Geomorphology
Slope
CVI
Turkey Point
Very High Moderate Moderate
Low
Very High
Very High
High

55

Figure 8. Turkey Point with a sea level rise of 0.4 m and 0.5 m.

56

Figure 9. Turkey Point with a sea level rise of 0.9 m.

57

Figure 10. Turkey Point with a sea level rise of 2.5 m.

58

4.1.4. Seabrook Station
Seabrook Station began commercial operation in 1990 and the license expires in
2026. The reactor has 18 years remaining in operation and the total life of the reactor
remaining was determined to be 82 years. Seabrook Station is located on the western
shore of Hampton Harbor in Rockingham County, in the township of Seabrook, New
Hampshire. It is approximately 11 miles south of Portsmouth, New Hampshire and 2
miles west of the Atlantic Ocean. The site area is characterized by broad open areas of
tidal marsh, dissected by numerous tidal creeks and man-made linear drainage ditches
(U.S. Nuclear Regulatory Commission, 2008c). Figure 11 provides a view of the site
superimposed with the digital elevation model used in the study.
The design basis flood was determined to be 6.19 m (20.6 feet) from a
combination of the probable maximum hurricane combined and precipitation from the
standard project storm (U.S. Nuclear Regulatory Commission, 2008c). Safety related
equipment is designed to withstand a depth of still water of 0.18 m (0.6 feet) on the plant
grade of 6.1 m (20 feet) above mean sea level. The walls of safety related structures can
withstand a wave runup of 6.64 m (21.8 feet) above mean sea level (U.S. Nuclear
Regulatory Commission, 2008c).

59

Figure 11. Satellite imagery of Seabrook Station with Digital Elevation Model overlay.

60

Table 16. Sea level rise scenarios and results for Seabrook Station.
Model Cannot Determine

Considerable Flooding

Scenarios
Conditions

Current
Storms

End of
Operation

Life of
Reactor

100 Years
Low

100 Years Mid/150
Years Low

100 Years
High

Sea Level Rise
1m

150 Years
High

0.08

0.35

0.51

0.72

0.85

1.00

1.21

Northeastern

0.6

0.68

0.95

1.11

1.32

1.45

1.60

1.81

Category I Low

1.2

1.28

1.55

1.71

1.92

2.05

2.20

2.41

Category I High

1.5

1.58

1.85

2.01

2.22

2.35

2.50

2.71

Category II

2.4

2.48

2.75

2.91

3.12

3.25

3.40

3.61

Category III

3.7

3.78

4.05

4.21

4.42

4.55

4.70

4.91

Category IV Low

4

4.08

4.35

4.51

4.72

4.85

5.00

5.21

Category IV High

5.5

5.58

5.85

6.01

6.22

6.35

6.50

6.71

Sea Level Rise

The digital elevation model for Seabrook Station has a 1 m vertical resolution; therefore, flooding can not be determined for sea
level rise scenarios below 1 m as shown in Table 16. A rise in sea level of 1 m appears to cause significant flooding of the site as shown in
Figure 12. In Figure 13, roads to the north of the site flood with a rise in sea level of 3 m. A rise of 6 m leads to a substantial increase in
flooding, and in particular access becomes increasingly limited due to flooding of roads as shown in Figure 14. All scenarios for the life
of the reactor are less than the design basis flood event. Overall the coastal vulnerability index (CVI) is ranked low, but geomorphology
and waves rank very high and high respectively as shown in Table 17. Changes in wave height and strength due to sea level rise and
storms could be a future concern.

Table 17. Relative vulnerability of each of the coastal variables and overall variability of the coastline at Seabrook Station.
Reactor
Tide
Waves
Erosion Sea Level Rise Geomorphology
Slope
CVI
Seabrook
Moderate
High
Moderate
Very Low
Very High
Very Low
Low

61

Figure 12. Seabrook Station with a sea level rise of 1 m.

62

Figure 13. Seabrook Station with a sea level rise of 3 m.

63

Figure 14. Seabrook Station with a sea level rise of 6 m.

64

4.1.5. Pilgrim Station
Pilgrim Station began operation in 1972 and the license expires in 2012. Pilgrim
Station has 64 years remaining in the reactor lifetime. The reactor has 4 more operating
years and 24 years if the license is renewed. Pilgrim Station is located on the western
shore of Cape Cod Bay in the Town of Plymouth, Plymouth County, Massachusetts.
Approximately 60% of the area within a 50-mile radius of Pilgrim Stations is open water
(Entergy, 2005). Figure 15 provides a view of the site superimposed with the digital
elevation model.
The maximum flood level for Pilgrim Station is 4.4m (14.7 feet), but this
calculation does not include wave runup. The site is flood protected to an elevation of 6.9
m (23 feet) (U.S. Nuclear Regulatory Commission, 2002).

65

Figure 15. Satellite imagery of Pilgrim Station with Digital Elevation Model overlay.

66

Table 18. Sea level rise scenarios and results for Pilgrim Station.
Model Cannot Determine

Considerable Flooding

Scenarios
Current
Storms

Conditions
Sea Level Rise

End of
Operation

License
Extension

Life of
Reactor

100 Years
Low

100 Years Mid/
150 Years Low

100 Years
High

Sea Level
Rise 1m

150 Years
High

0.02

0.10

0.28

0.51

0.72

0.85

1.00

1.21

Northeastern

0.6

0.62

0.70

0.88

1.11

1.32

1.45

1.60

1.81

Category I Low

1.2

1.22

1.30

1.48

1.20

1.92

2.05

2.20

2.41

Category I High

1.5

1.52

1.60

1.78

1.50

2.22

2.35

2.50

2.71

Category II

2.4

2.42

2.50

2.68

2.91

3.12

3.25

3.40

3.61

Category III

3.7

3.72

3.80

3.98

4.21

4.42

4.55

4.70

4.91

Category IV Low

4

4.02

4.10

4.28

4.00

4.72

4.85

5.00

5.21

Category IV High

5.5

5.52

5.60

5.78

5.50

6.22

6.35

6.50

6.71

The digital elevation model for Pilgrim Station has a 1 m vertical resolution; therefore, flooding can not be determined for sea
level rise scenarios below 1 m as shown in Table 18. The site floods with 1 m sea level rise as shown in Figure 16. Roads begin to
flood at 3 m, and at 4 m the roads are flooded considerably as shown in Figure 17. Figure 18 reveals that exits may be blocked with a
rise in sea level of 6 m, and at 7 m the entire site is close to inundation. The site is designed to withstand all flood scenarios generated
here. The coastal vulnerability index (CVI) of the site is low, while geomorphology receives a high ranking as shown in Table 19.
Table 19. Relative vulnerability of each of the coastal variables and overall vulnerability of the coastline at Pilgrim Station.
Reactor
Tide
Waves
Erosion Sea Level Rise Geomorphology
Slope
CVI
Pilgrim
Moderate Moderate Very Low
Low
High
Very Low
Low

67

Figure 16. Pilgrim Station with a sea level rise of 1 m.

68

Figure 17. Pilgrim Station with a sea level rise of 4 m.

69

Figure 18. Pilgrim station with a sea level rise of 6 m and 7 m.

70

4.1.6. Millstone
Millstone-3 began operation in 1986 and the license has been extended to 2045.
Millstone has 37 years remaining in operation and the total life of the reactor remaining
was determined to be 78 years. Millstone Power Station is located in Waterford,
Connecticut, on Millstone Point, between the Niantic and Thames Rivers on Long Island
Sound. Millstone is sited on a peninsula that includes rocky beaches, coastal tidal
marshes, and second-growth hardwood forests (U.S. Nuclear Regulatory Commission,
2005). Figure 19 provides a view of the site superimposed with the digital elevation
model used in the study.
The probable maximum flood at the Millstone site is 7.5 m (25.1 feet). Flood
gates and other measures provide protection to a height of 8.4 m (28 feet) above mean sea
level (U.S. Nuclear Regulatory Commission, 2002)

71

Figure 19. Satellite imagery of Millstone with Digital Elevation Model overlay.

72

Table 20. Sea level rise scenarios and results for Millstone.
Model Cannot Determine

No Flooding

Potential For Flooding

Considerable Flooding

Scenarios
Conditions

Current
Storms

Sea Level Rise

End of
Operation

Life of
Reactor

100 Years
Low

100 Years Mid/
150 Years Low

100 Years
High

Sea Level
Rise 1 m

150 Years
High

0.20

0.30

0.50

0.70

0.90

1.00

1.20

Northeastern

0.6

0.80

0.90

1.10

1.30

1.50

1.60

1.80

Category I Low

1.2

1.40

1.50

1.70

1.90

2.10

2.20

2.40

Category I High

1.5

1.70

1.80

2.00

2.20

2.40

2.50

2.70

Category II

2.4

2.60

2.70

2.90

3.10

3.30

3.40

3.60

Category III

3.7

3.90

4.00

4.20

4.40

4.60

4.70

4.90

Category IV Low

4

4.20

4.30

4.50

4.70

4.90

5.00

5.20

Category IV High

5.5

5.70

5.80

6.00

6.20

6.40

6.50

6.70

The site potentially begins to flood at 2 m as shown in Table 20 and Figure 20. At 3 m the buildings on the southern and eastern
side of the site, and the intake structures on the west side experience flooding. Further flooding occurs from 4 to 6 m as shown in Figure
21 and 22 respectively. Flooding does not reach the reactors or the main buildings located at the center of the site, or cover the roads that
enter the site in the north. Furthermore, the site is flood protected for conditions greater than the flood levels in any of the scenarios.
Overall the Millstone site received a low ranking for the coastal vulnerability index (CVI) as shown in Table 21.

Table 21. Relative vulnerability of each of the coastal variables and overall vulnerability of the coastline at Millstone.
Reactor
Tide
Waves
Erosion Sea Level Rise Geomorphology
Slope
CVI
Millstone
Very High Moderate Moderate
Very Low
Very Low
Very Low
Low

73

Figure 20. Millstone with a sea level rise of 2 m.

74

Figure 21. Millstone with a sea level rise of 4 m.

75

Figure 22. Millstone with a sea level rise of 6 m.

76

4.1.7. Calvert Cliffs
The younger of the two power plants on the Calvert Cliffs site began operation in
1977 and the license expires in 2036. Calvert Cliffs has 28 years remaining in operation
and the total life of the reactor was determined to be 69 years. UniStar is currently
applying for construction of a new reactor at this site. The Calvert Cliffs nuclear power
plant is in Calvert County, Maryland, on the west bank of Chesapeake Bay,
approximately halfway between the mouth of the bay and its headwaters at the
Susquehanna River. The current reactor is approximately 152.4 m (500 feet) from the
shore, while the new proposed reactor will be a 304.8 m (1000 feet) from the shoreline
(MACTEC Engineering and Consulting Inc., 2008). Figure 23 provides a view of the site
superimposed with the digital elevation model used in the study.
The flooding conditions considered in design include: the probable maximum
flood (PMF) on streams and rivers, potential dam failures, probable maximum surge and
seiche flooding, probable maximum tsunami and ice effect flooding. The Nuclear Island
of the new site is at an elevation of 24.8 m (81.5 ft) with respect to the reference level.
Safety-related structures of Nuclear Island have a minimum grade slab or entrance at
elevation 25.8 m (84.6 feet). The maximum flood level at the intake location is an
elevation of 12 m (39.4 ft) as a result of the surge, wave heights, and wave run-up
associated with probable maximum hurricane (UniStar Nuclear Development, 2008).

77

Figure 23. Satellite imagery of Calvert Cliffs with Digital Elevation Model overlay.

78

Table 22. Sea level rise scenarios and results for Calvert Cliffs.
No Flooding

Potential For Flooding

Scenarios
Conditions

Current
Storms

End of
Operation

Life of
Reactor

100 Years
Low

100 Years Mid/
150 Years Low

100 Years
High

Sea Level
Rise 1 m

150 Years
High

0.12

0.30

0.51

0.72

0.85

1.00

1.21

Northeastern

0.6

0.72

0.90

1.11

1.32

1.45

1.60

1.81

Category I Low

1.2

1.32

1.50

1.71

1.92

1.92

2.20

2.41

Category I High

1.5

1.62

1.80

2.01

2.22

2.22

2.50

2.71

Category II

2.4

2.52

2.70

2.91

3.12

3.12

3.40

3.61

Category III

3.7

3.82

4.00

4.21

4.42

4.42

4.70

4.91

Sea Level Rise

The site is at a high enough elevation that flooding from storm surges does not pose a considerable problem. Flooding could
potentially happen at 3.9 m and above, corresponding to an increase in storm intensity as shown in Table 22. Figures 24 and 25 illustrate
the flooding of the intake structure at 3.9 m and at 4.6 m respectively. Calvert Cliffs ranked very high in erosion and geomorphology and
received a very high ranking for the coastal vulnerability index (CVI) as shown in Table 23.

Table 23. Relative vulnerability of each of the coastal variables and overall variability of the coastline at Calvert Cliffs.
Reactor
Tide
Waves
Erosion Sea Level Rise Geomorphology
Slope
CVI
Calvert Cliffs
Very High Moderate Very High
High
Very High - High
Low
Very High

79

Figure 24. Calvert Cliffs with a sea level rise of 3.9 m.

80

Figure 25. Calvert Cliffs with a sea level rise of 4.6 m.

81

4.1.8. San Onofre
San Onofre Nuclear Generating Station (SONGS) Unit-3 began operation in
1983 and the license will expire in 2022. The reactor has 14 years remaining in the
operating license and the life of the reactor was determined to be 75 years. San Onofre is
located in north San Diego County, California and is fronted by a narrow beach along the
Pacific Ocean. Figure 26 provides a view of the site superimposed with the digital
elevation model used in the study.
For purposes of determining and analyzing potential flood sources, consideration
was given to the San Onofre Creek Basin and the foothill drainage area east of the site.
The probable maximum flood level (PMFL) for the SONGS 2 and 3 site is 7.3 m (24.1
feet). Topographical feature of the basin would contain this flow and thereby preclude
flooding of the site by this source. Any openings and penetrations below the PMFL are
either sealed, protected by watertight doors/hatches, protected by waterstops, or analysis
has shown that PMF cannot impact safety-related equipment. Tsunamis caused by active
trench system are considered along with those generated by large scale tectonic
movement. Structures designed to protect the site include the seawall. The plant grade is
at an elevation of approximately 6.1 m (20 feet) MLLW (Southern California Edison
Company et al., 2002). This elevation is well above the maximum seawater elevation of
4.8 m (15.8 feet) mean lower low water that is predicted to occur in the event of a
maximum tsunami coincident with storm surge and high tide (Haney, 2006)

82

Figure 26. Satellite imagery of San Onofre with Digital Elevation Model overlay.

83

Table 24. Sea level rise scenarios and results for San Onofre.
No Flooding

Scenarios
Conditions

End of Operation

Life of Reactor

100 Years
Low

100 Year Mid/150 Years Low

100 Years
High

Sea Level
Rise 1 m

150 Years
High

Sea Level Rise

0.04

0.23

0.38

0.59

0.85

1

1.1

SLR and El Niño

0.3

0.53

0.68

0.89

1.15

1.3

1.4

Storm Surge

0.7

0.93

1.08

1.29

1.55

1.7

1.8

Wave Induced Storm

1.5

1.73

1.88

2.09

2.35

2.5

2.6

Flooding does not occur under any of the scenarios as shown in Table 24. The sea wall and the plant grade is at a high enough elevation to
prevent flooding from coastal storms. The coastal vulnerability index (CVI) for the San Onofre site ranks high as shown in Table 25.

Table 25. Relative vulnerability of each of the coastal variables and overall vulnerability of the coastline at San Onofre.
Reactor
Tides
Waves
Erosion Sea Level Rise Geomorphology Slope
CVI
San Onofre
High
Low
Moderate High
Moderate
Low
High

84

4.1.9. Diablo Canyon
The second reactor unit at Diablo Canyon began operation in 1986, and the
license will expire in 2025. The reactor has 17 operating years remaining, and the total
life left in the reactor was determined to be 78 years. The Diablo Canyon nuclear power
plant is located on the Pacific Ocean coastline in San Luis Obispo County, California,
approximately 12 miles west-southwest of the city of San Luis Obispo. Figure 26
provides a view of the site superimposed with the digital elevation model used in the
study.
Site flooding includes the combined effects of flooding from steams and rivers
(Diablo Creek), a tsunami, wind-generated storm waves, storm-surge, and tides. For
flooding from steams and rivers, there is the probable maximum flood (PMF) from the
probable maximum precipitation (PMP) with duration of 24 hours and all culverts
plugged. The combination of tsunami, wind-generated storm waves, storm-surge, and
tidal effects results in a rise and fall of the ocean surface level relative to a defined datum
level, the mean lower low water level (MLLWL). For the plant site, the MLLWL is 0.7 m
(2.6 feet) below the mean sea level (MSL) (Haney, 2006). The PMF was found to have a
peak discharge of 6878 cubic feet per second for the 24-hour storm. For the tsunami
runup and drawdown, the wave heights for distantly-generated and locally-generated
(near shore) tsunamis were considered. For distantly-generated tsunamis, the design
combined drawdown and wave runup is 2.74 m (9 ft) and 9.14 m (30 ft), respectively. For
near-shore tsunamis, the design combined drawdown and wave runup is 1.3 m (4.4 ft)
and 10.5 m (34.6 ft). This is the probable maximum surge (PMS) for the site (Haney,
2006).

85

Figure 27. Satellite imagery of Diablo Canyon with Digital Elevation Model overlay.

86

Table 26. Sea level rise scenarios and results for Diablo Canyon.
No Flooding

Scenarios
Life of Reactor

100 Years
Low

100 Years Mid/150 Years Low

100 Years
High

Sea Level
Rise 1 m

150 Years
High

0.85

1

1.09

1.15

1.3

1.4

1.29

1.55

1.70

1.79

2.09

2.35

2.50

2.59

Conditions

End of Operation

Sea Level Rise

0.05

0.23

0.38

0.59

SLR and El Niño

0.4

0.534

0.68

0.89

Storm Surge

0.8

0.93

1.08

Wave Induced Storm

1.6

1.73

1.88

The site did not flood under any of the scenarios as shown in Table 26. The elevation of the site is high enough to prevent
flooding from storm surges and the design basis flood is also greater than any of the sea level rise scenarios. The coastal vulnerability
index (CVI) for the Diablo Canyon site ranks low as shown in Table 27.

Table 27. Relative vulnerability of each of the coastal variables and overall vulnerability of the coastline at Diablo Canyon.
Reactor
Tides
Waves
Erosion Sea Level Rise Geomorphology Slope
CVI
Diablo Canyon High
Low
Moderate Low
Very Low
Moderate Low

87

4.1.10. Sea Level Rise and Coastal Vulnerability Discussion
The models used here have limitations that must be considered when interpreting
the results. For the most part the limitations in the model will lead to results that
underestimate the level of flooding that will occur rather than overestimate. First, there is
a great deal of uncertainty in the amount of sea level rise that can be expected by the end
of the century. Generating scenarios that cover a range of possibilities provide a means
to deal with some of that uncertainty; however, abrupt changes in sea level still remain a
possibility.
Depending on site conditions, storm surges could be less than the surge heights
used in this model or they could be greater. Storm surge always coexists with
astronomical tides and the model’s limitation prevents the prediction of the effects of a
storm hitting at high tide. The Saffir-Simpson surge table is a crude estimate of the
amount of surge generated by hurricanes. In reality, bathymetry determines the amount
of storm surge created by a particular strength of hurricane. Moreover, as sea level rises
allowances must be made for changing depths and boundary positions which will affect
bottom stresses (Pugh, 1987). Higher sea levels create a larger expanse of shallow water
resulting in increased storm surge elevations compared to areas of steep offshore slopes.
However, if the shoreline is fixed and the offshore water depths increase, then the storm
surges will be reduced (U.S. National Research Council, 1987). This method was limited
in that it is unable to account for tides which on the California coast extreme tide ranges
approach 3 m (10 feet) (Flick & Badan-Dangon, 1989). The California sites also did not
include an estimate for an increase in storm intensity.
In addition, the model is not able to allow for the possibility of large waves that
could overtop defensive flood structures and the precipitation that accompanies storms.
While the coastal vulnerability index considers current wave height, changes in wave
height and energy are not included in the model. Wave height will change because the
offshore water depth will be greater with rising sea level, and storm waves that propagate
inland will be larger than before (U.S. National Research Council, 1987). Moreover,
complex changes in sediment transport processes in the near shore environment can occur
with a change in sea level and makes predicting erosion increasingly difficult.
Nonetheless, the inundation model and coastal vulnerability index reveal those

88

sites that are the most vulnerable to sea level rise. In particular, it is worthwhile to
understand potential problems that each of these sites might have from flooding, erosion,
and landslides. Refer to Appendix 9 for the actual numerical values for the variables
considered in the coastal vulnerability assessment at each site.
Seabrook and Pilgrim Station in New Hampshire and Massachusetts respectively,
and all three sites in Florida were found to be the most vulnerable to flooding from rising
sea level as shown in Table 28. The reactors are designed to withstand the flood
scenarios generated here, but Turkey Point and St. Lucie approach design limits within
the life of the reactor. In addition, future reactor construction at these locations will need
more flood protection. While the Florida sites have the most dramatic impact from
inundation, Turkey Point and St. Lucie also have a high to very high coastal vulnerability
index.

Table 28. Summary of results for flooding due to sea level rise and coastal vulnerability.
Site Name
State
Flooding Level Coastal Vulnerability
St. Lucie
Florida
Inundated
Very High – High
Crystal River
Florida
Inundated
Moderate
Turkey Point
Florida
Inundated
High
Seabrook
New Hampshire
Considerable
Low
Pilgrim
Massachusetts
Considerable
Low
Millstone
Connecticut
Considerable
Low
Calvert Cliffs
Maryland
Potential
Very High
San Onofre
California
None
High
Diablo Canyon
California
None
Low

St. Lucie is particularly vulnerable due to its location on a barrier island. Erosion
has been occurring along Hutchinson Island at a rapid rate and is apparent from tree
stumps and clay beds on the beach. Furthermore, several beach nourishment projects
have been conducted over the years (Pilkey Jr. et al., 1984). Evacuation is a major
problem from the islands of St. Lucie County, since all bridges are drawbridges, and the
escape road along the island's length is frequently at elevations of less than 1.5 m (5 feet)
and within a few feet of the Indian River shoreline. During a severe storm there is a
strong likelihood that new inlets will break through some of the narrow portions of the
islands, thereby, challenging evacuations even further (Pilkey Jr. et al., 1984).
The Calvert Cliffs site has only a potential of flooding. The surge model used in
this study might be too conservative. The largest tidal flood that is likely to occur under

89

the most severe meteorological and hydrological conditions in Cheaspeake Bay is 4 m
(13 feet) above the national geodetic vertical datum, while waves can reach an additional
1.5 m (5 feet) (Ward et al., 1999). Nonetheless, this level of surge is accounted for in the
design of the new reactor and the existing reactors are at an elevation of at least 11 m (36
feet). While Calvert Cliffs appears resistant to flooding it received a very high ranking
for coastal vulnerability. The Chesapeake Bay region is ranked the third most vulnerable
to sea level rise behind Louisiana and Southern Florida. Maryland is currently losing
approximately 580 acres of land per year to shore erosion; therefore, coastal erosion is
and will continue to be one of the most severe impacts of sea level rise in Maryland
(Maryland DNR, 2007; Mayrland DNR, 1999).
Similar to Calvert Cliffs, San Onofre is resistant to flooding, but receives a high
rank for coastal vulnerability. The San Onofre power plant is located on the coastal
terrace, which is underlain by Miocene marine rock capped by Pleistocene marine and
nonmarine sediments (Kuhn, 1980). These Pleistocene sediments are essentially
horizontal and are easily eroded from the bluff face and along the canyons.
Approximately 80 percent of the cliffs between the power plant and Target Canyon six
miles to the south, on Camp Pendleton, consist of landslides (Kuhn, 1980). Furthermore,
where protective measures project or extend seaward beyond adjacent unprotected lots,
there is immediate erosion and notching of the unprotected sites. As beach sand levels
fall, storm waves tend to converge on projecting structures and the waves refract toward
unprotected lots (Kuhn & Shepard, 1983). The San Onofre facility itself is not at risk
from erosion or flooding owing to massive double-seawall protection; however, adjacent
beaches have narrowed since 1985 (Griggs et al., 2005).
Diablo canyon received a low ranking for coastal vulnerability, erosion in the
area is moderate, and sea level rise is not a concern due to the elevation of the site.
Increases in precipitation from coastal storms likely pose more of a hazard at this site
than ocean conditions. During two El Niño years, mud slides and flooding from an
intense precipitation event restricted access to the plant (Becker, 1995; Skaggs, 1997). In
the 1995 event, site personnel could not come on site to relieve the watch, emergency
sirens were inoperable due to power outages, and one of the switching centers
experienced flooding. Furthermore, power for one of the units was reduced to about 50%
as a precautionary measure due to ocean conditions (Becker, 1995). The impact of a

90

coastal storm is not limited to flooding: low tides can also be hazardous. In 1985, rough
seas combined with low tide caused a build up of kelp at the intake at Diablo Canyon.
The kelp broke down and plugged the unit-2 circulators. During controlled shutdown of
unit-2 a digital rod position indication failure alarm was received, resulting in the need to
manually shut-down the reactors (Sicard, 1985).
The frequency of hazardous events, in particular flooding, will increase due to
climate change. What measures were taken in the past to adapt operations to the harsh
coastal environment? What problems remain despite the lessons learned from past
experience? The next section will evaluate the operational experience at coastal locations
and explore these vulnerabilities further.

4.2. Operational Experience
When one considers the variability of climate on longer time-scales, the
operation of nuclear power plants has benefited from a relatively calm coastal
environment. Nonetheless, storms have reached coastal nuclear power plants, and from
that we can infer the problems that will arise from storms of increasing intensity or
frequency. Several safety issues repeatedly arise during storm events including: the loss
of offsite power, failure of communication systems and alarm systems, and obstruction of
evacuation routes.
The availability of AC power to commercial nuclear power plants is essential for
safe operations and accident recovery; therefore, a loss of offsite power event is an
important contributor to total risk at nuclear power plants. An assessment conducted in
1998 of loss of offsite power events at U.S. nuclear power reactors found that sixteen of
the 22 events resulting from severe weather occurred at only 5 sites. The five sites were
Pilgrim Station in Massachusetts, Crystal River in Florida, Brunswick in North Carolina,
Millstone in Connecticut, and Turkey Point in Florida. The units at these sites have
diverse designs with little similarity in electrical power supply design or redundancy;
therefore, it was concluded that the proximity of the sites to the east coast was a major
factor in loss of power frequency (Atwood et al., 1998).
However, the predictability of hurricanes does allow time for preparation. The
U.S. Nuclear Regulatory Commission (NRC) has an established hurricane response
program that is implemented each year during hurricane season. The NRC monitors

91

potentially hazardous weather conditions in the Atlantic and Pacific Oceans, the
Caribbean Sea, and the Gulf of Mexico. For the Atlantic basin, the NRC monitors
tropical storm formations developing as far away as the African coast. The NRC relies on
hurricane tracking computer programs and data provided by the National Oceanic and
Atmospheric Administration that provides current and projected information about
developing storms (Leach et al., 2006). Nuclear power plant licensees prepare well in
advance by updating procedures and assessing their sites for readiness at the beginning of
each hurricane season (Leach et al., 2006). Detailed site-specific emergency plans and
implementing procedures provide instructions and guidelines for dealing with or
responding to a variety of emergency situations, including natural phenomena such as
hurricanes. These integrated emergency plans are developed in a coordinated manner
between the facility licensee and State and local authorities, with oversight by the NRC
and Department of Homeland Security/Federal Emergency Management Agency
(DHS/FEMA)(Leach et al., 2006). Moreover, formal procedures require that each
nuclear power plant take specific actions under weather conditions specific to each site
including shutdown of the reactor in anticipation of hurricane force winds (Leach et al.,
2006). While shutdown of the reactor is vital to safe operation, the restart of the reactor
requires approval from both the NRC and FEMA that may take days to weeks thereby
disrupting the power supply.
Hurricane Andrew in 1992 was the first time a hurricane significantly affected a
commercial nuclear plant (U.S. Nuclear Regulatory Commission, 1994). The analysis for
wind indicated a need to modify the flood wall and improve the emergency procedure for
Category 5 hurricanes. Hurricane Andrew caused damage to a number of non-safety
structures and equipment at Turkey Point including: collapse of all steel-framed turbine
canopies, damage to one of the chimneys belonging to the fossil fuel units, movement of
the base anchors for the vent stack on the Unit 4 containment, failure of the ductwork
from the radioactive waste building, and the collapse of the non-safety high-water tank
onto the fire protection pumps and pipes thereby rendering one of the fire protection
systems inoperable. This event demonstrated the need to either design non-safety
structures and equipment to withstand the postulated events, or assure that the
consequences of their failure would not disable the safety functions of safety-related
structures, systems and components (U.S. Nuclear Regulatory Commission, 1994).

92

Prior to the storm, on August 23, 1992, the licensee shut down both reactors and
placed them in the “hot standby” condition as required by the plant emergency
procedures. The plant lost all offsite power during the storm and for over five days after
the storm (Leach et al., 2006). Furthermore, wind damage caused the loss of all
communication at Turkey Point Nuclear Generating Station. As a result of this
experience, the NRC arranged for portable satellite communication equipment to be
available at sites as required (Leach et al., 2006). Many false alarms in the spent fuel
containment created concerns because it was not accessible during the storm (IAEA,
2003b). In addition, the security system sustained extensive damage specifically to
equipment including: lighting, cameras, intrusion detection equipment, protective area
fencing, and the entrance building (Leach et al., 2006).
The impact of hurricanes on nuclear power plants is not limited to sites
immediately along the coast, but can cause problems a considerable distance inland as
demonstrated by Hurricane Isabel in 2003. Several nuclear plants had inoperable
emergency sirens due to power outages resulting from the storm including: Hope Creek
and Salem in New Jersey, Harris-1 in North Carolina, and Peach Bottom, Three Mile
Island-1 and Limerick in Pennsylvania, and Calvert Cliffs in Maryland (Washington
staff, 2003). The Surry units in southeastern Virginia were taken off line manually after a
transformer that powers the water circulation pumps at an intake canal lost power. High
winds also knocked down trees and temporarily blocked access to the site. Surry-1
returned to service within a few days after approval of the NRC and FEMA and reached
full power after five days (Washington staff, 2003). The impact of a storm is not always
immediate. Hope Creek and Salem shutdown for several days after Hurricane Isabel had
passed. The storm had created heavy waves and fog in the Delaware River, producing
saline water vapor that left salt deposits in the plants' switchyards causing electrical faults
and arcing (Washington staff, 2003).
The 2004 and 2005 hurricane seasons had the most significant impacts on the
operation of nuclear power plants. Multiple hurricanes affected the operation of nuclear
power plants during the 2004 hurricane season: Hurricane Charley impacted the
Brunswick site in North Carolina, Hurricane Frances impacted the operation of St. Lucie
and Crystal River in Florida, and St. Lucie was impacted again by Hurricane Jeanne
(Kauffman, 2005). The reportable impacts on the nuclear power plants were mainly

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confined to the loss of offsite power, loss of sirens, and loss of communications
equipment. One insight gained was that site access during hurricanes is as important as
the communications and siren issues. Security concerns were mentioned in a report on the
impact of the 2004 hurricane season; however, due to the sensitivity of the subject matter
details were not provided (Kauffman, 2005). The loss of off-site power at Brunswick and
Crystal River was due to undetected degraded transmission line insulators failing during
the storm conditions. Brunswick and St. Lucie had problems related to switchyard
designs that were not robust during extreme weather conditions. All three sites had
breaker faults or failures related to salt contamination or moisture intrusion. Moreover,
the licensee at one site stated that preventive and corrective maintenance activities had
not identified moisture buildup as a condition requiring corrective action (Kauffman,
2005).
In addition to these equipment problems, all three plants experienced unexpected
equipment malfunctions or failures during their events. Brunswick had failures of the Btrain standby gas treatment. St. Lucie experienced problems with a feed-water regulating
valve and a breaker for an intake cooling water pump. Crystal River had an overloaded
alarm system and failure of an emergency lube oil pump for a main feed-water pump
turbine. The most significant finding was after the hurricane passed the St. Lucie site.
The reactor auxiliary building’s missile shield doors were found open; thereby, risking
exposure of safety-related equipment to tornado-induced missiles. The licensee stated
that the doors could have been open for several years (Kauffman, 2005).
The 2005 hurricane season took its toll on a different suite of nuclear power
plants. The Grand Gulf plant in Mississippi, the River Bend plant in Louisiana, and the
Waterford 3 plant in Louisiana, were more affected by Hurricane Katrina than the plants
located in Florida (Leach et al., 2006). The three power plants did not sustain significant
damage. Waterford -3 was the nuclear power plant closest to the hurricane’s path and
shut down on August 28th as Hurricane Katrina made its approach toward Louisiana
(Weil, 2005a, 2005b). Waterford-3 received clearance to restart September 9th, but it
took more than two weeks for the plant to return to service after shutting down (Weil,
2005c). River Bend and Grand Gulf did not shut down during the storm, but voluntarily
reduced power to assist in restoring stability to the electrical grid when a drop in energy
consumption caused grid voltage to fluctuate (Weil, 2005b). Winds knocked out 17 of

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the 43 emergency sirens in the area near the Grand Gulf station placing the number of
required sirens less than the operability rate of 75% (Weil, 2005b). Land-line and cellular
communications at the Waterford 3 site were lost because of flooding, electrical outages,
and wind damage in the New Orleans area. To address the loss of land-line
communication, extra land lines were installed and satellite communications equipment
was employed for communication following the hurricane’s passage at this site.
However, satellite phones were not as robust as was anticipated, since cloud cover
interrupted the reception, operators had to go outside to use them (Leach et al., 2006). In
addition, offsite power was lost because of instability in the regional electrical grid. In
response to the loss of offsite power, electrical power for key safety systems for the
Waterford 3 plant was supplied automatically by the plant’s standby diesel generators.
Prior to the hurricane, the licensee for the Waterford 3 facility obtained two additional
diesel generators to supplement the installed units and placed them on site (Leach et al.,
2006).
The 2004 and 2005 hurricane season interrupted the operation of nuclear power
plants and the transmission of power enough to cause financial concerns for the
companies involved. However, the costs were more related to infrastructure damage
rather than damage to the nuclear power plants. Uncertainty surrounding when hurricane
costs will be fully recovered prompted Standard & Poor's Ratings Services (S&P) to
revise its outlook to negative from stable on 'BBB' issuer credit ratings for Progress
Energy Inc. Progress Energy which owns Brunswick and Shearon-Harris nuclear plants
in North Carolina, Robinson-2 in South Carolina, and Crystal River-3 in Florida has
estimated its costs from three of the four hurricanes that battered Florida and other parts
of the south in 2004 at $310- to $330-million. Though the total includes all Progress
Energy plants, the bulk of the costs were incurred at the Florida sites (Hiruo, 2004).
After Katrina, Entergy Corporation warned investors in a September 6th filing with the
Securities & Exchange Commission that the hurricane would have a financial impact on
the company's earnings. It said revenues would be lower than expected because of
extended outages and the inability to bill and collect revenues from customers whose
property was destroyed. Moreover, it expected capital expenditures to rise as it begins
restoration and repairs in the affected service areas (Weil, 2005c).

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4.3. Design Concerns
Storms have caused safety problems regardless of the measures taken to address
external events in design. An additional concern is whether the margins used in design
are enough to accommodate climate change. The historical climate record can not be
relied upon to predict future climate. Further, anticipatory measures must be taken to
adapt to climate change and to ensure that structures withstand extreme climate events. In
reviewing U.S. NRC documents I was unable to find any indication that models currently
used to determine maximum flood and storm conditions incorporate climate change.
Moreover, models generated by the National Oceanic and Atmospheric Administration
(NOAA) and the Army Corps of Engineers lead to different results with the NOAA
model indicating current design margins were not adequate at one nuclear power plant
site. The U.S. NRC chose to use models that gave more conservative results when it
would be prudent to use greater safety margins to accommodate climate change.
Hurricane design is based on studies conducted by the Environmental Science
Services Administration and the Coastal Engineering Research Center for those sites that
are exposed to the full force of hurricane winds. The design is considered to provide full
protection against hurricane winds, tides, and wave action for the worst hurricane
reasonably possible at the site: the probable maximum hurricane (PMH) (Haney, 2006).
The PMH is defined by the National Weather Service as a hypothetical hurricane having
that combination of characteristics which will make it the most severe that can probably
occur in the region involved. The PMH is assumed to approach the plant site along the
critical path, and at the optimum rate of movement (Haney, 2006). The values for the
PMH are developed from storm history over a wide stretch of coast extrapolated out
about 2000 years, while probable maximum precipitation values are developed from the
100 year record maximum for the area (U.S. Nuclear Regulatory Commission, 2008b).
Precipitation events are predicted to increase in frequency and intensity due to climate
change, and the 100 year record does not capture climate variability of longer timescales.
Similarly, wind design should incorporate the possibility of changes in wind
speed and direction, but these considerations are not apparent in the U.S. NRC model
descriptions. The wind speeds used in the design of safety-related structures of east-coast

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plants vary from 177 to 210 km/h (110 to 130 mph). As the load factor used with the
design wind loading is 1.7 these structures can withstand Category 4 and low intensity
Category 5 hurricanes. The design against tornado generated loadings provides margin
against failure of safety-related structures during hurricanes (U.S. Nuclear Regulatory
Commission, 1994). Still, as shown in Table 29, St. Lucie and Crystal River are the only
reactors designed specifically to withstand a category 5 hurricane.
Table 29. Wind designs for nuclear power plants that are in the direct path of hurricanes
(Haney, 2006).
Reactor
State
Sustained Wind
Tornado
Brunswick
North Carolina
217 km/h (135 mph)
483 km/h (300 mph)
Crystal River
Florida
288 km/h (179 mph)
483 km/h (300 mph)
St. Lucie
Florida
312 km/h (194 mph)
483 km/h (300 mph)
South Texas Project
Texas
201 km/h (125 mph)
579 km/h (360 mph)
Turkey Point
Florida
233 km/h (145 mph)
542 km/h (337 mph)

The storm surge typically causes the most damage to structures, and determining
surge levels is exceptionally difficult. A disagreement between two different models, one
developed by the National Oceanic and Atmospheric Administration (NOAA) and the
other by the U.S. Army Corps of Engineers for the Brunswick site in North Carolina was
revealed in a 2000 U.S. NRC memo (Thadani, 2000). The Brunswick plant is located
approximately two miles west of the Cape Fear River, and approximately five miles west
of the Atlantic Ocean and due to the curvature of the coastline in this area, the ocean also
lies about four miles south. The plant is subjected to the full force of hurricane winds
(Haney, 2006). A NOAA study published in 1992 used a different methodology and
found surge elevations which, in the case of the Brunswick nuclear plant, exceeded the
design basis flood level by 2 m (6.4 feet). The surge elevation of 8.66 m (28.4 feet)
calculated by NOAA for the Brunswick site was based on a combination of parameters
consistent with an extreme hurricane. NOAA refused to release its model, so evaluating
the model proved difficult. Nonetheless, the U.S. NRC communication had several
critiques of the results. For instance, the storm may not be realistic, because the
parameters were assumed to be independent, and because the combination of parameters
used may be unrealistic. In addition, certain roads in the vicinity of the site may not have
been included in the calculations. In particular, highways 211, 87, and 133 could act as
levees along the storm path chosen, thus impeding storm surge propagation. The model

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showed considerable surge beyond the highways, suggesting that they may not have been
properly represented in the model (Thadani, 2000). However, an alternative explanation
is that the model determined that the roads would not hold up to the undercutting caused
by the dynamic action of the surge. NOAA’s findings cast doubt on the adequacy of the
design basis for the Atlantic coast nuclear power plants and of the NRC regulations used
to determine the design basis. Consequently, the Brunswick plant had an independent
assessment made of the NOAA report, including a new set of calculations, to verify that
the design basis flood level provides adequate safety for the plant.
The Army Corps of Engineers was contracted to derive realistic water level
frequency relationships for the Brunswick plant using state-of-the-art techniques of
modeling and statistical analysis (Thadani, 2000). The 2000 memo provided detailed
description on how the new surge levels were determined. The Coastal and Hydraulics
Laboratory (CHL) at the Engineer Research and Development Center of the U.S. Army
Corps of Engineers performed hurricane stage-frequency analyses for the five plants
using a statistical technique named the empirical simulation technique (EST). This
approach takes historical data consisting of storms and their storm parameters plus the
response vector (the storm surge) and builds up a larger database by introducing small
perturbations to the parameters. The EST also uses statistical re-sampling and nearest
neighbor, random walk interpolation. In this procedure, hurricanes from a data set are
selected randomly. One of the hurricane parameters is selected and the three hurricanes
with the closest values are determined for use in interpolation. The same procedure is
then applied to other hurricane parameters. Historical data are used to develop joint
probability relationships among the various measured storm parameters. No simplifying
assumptions are used so that the interdependence of parameters is preserved. The only
assumption used is that future events will be statistically similar to past events in
magnitude and frequency. From a historical data set, the CHL selected a subset of storm
events, called a “training” set that is representative of the entire set of historical storms
(Thadani, 2000). Assuming the same magnitude and frequency of hurricanes is a flawed
assumption; furthermore, the memo does not indicate the time period of the historical
data set that was used. However, the memo does state that random perturbations may
result in more intense storms than the historical events, so a future hurricane may be the
storm of record (Thadani, 2000).

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The new analyses were then compared with the hurricane induced surge
elevations resulting from the NOAA and Brunswick studies. Later, the study was
extended to include four more coastal nuclear plants, namely Crystal River, Turkey Point
and St. Lucie, in Florida; and Oyster Creek in New Jersey. The EST analysis predicted a
total surge elevation of 4.9 to 5.2 m (16 to 17 feet) MSL for a 2000 year return period.
This elevation is 1.5 to 1.8 m (5 to 6 feet) lower than the 6.7 m (22 feet) design basis for
the plant, which was computed using the probable maximum hurricane. The probable
maximum hurricane is also estimated for a return period of 2000 years. In the case of the
other four plants (Turkey Point, St. Lucie, Crystal River, and Oyster Creek), the EST
derived levels were lower than the design levels by 0.3 m (1 foot), 2.4 m (7.8 feet), 8.1 m
(26.5 feet), and 3.7 m (12.1 feet), respectively (Thadani, 2000). Considering predictions
of sea level rise a 0.3 m (1 foot) margin is probably not adequate.
The U.S. NRC concluded that the NOAA study results are inconsistent with the
other sets of data and provide storm surge levels that are overly conservative. This
discrepancy was thought to be due to the fact that the hypothetical storms used in the
study are based on the joint probability method, and do not realistically replicate the
historic storms in the study region. Although the synthesized storms may be similar to
historic ones, their probability of occurrence seems to be greater (Thadani, 2000). Thus,
the methodology used by NOAA was criticized for predicting more intense storms that
may occur more frequently.
The U.S. Army Corp of Engineers’ analysis of hurricane storm surge levels for
five plants on the Atlantic and Gulf coasts showed that the design basis flood levels of
these plants are adequate and the U.S. NRC closed related safety issues. The two units of
the Brunswick nuclear plant were licensed in 1974 and 1976 with a design basis flood
level of 6.7 m (22 feet) derived from Reg. Guide 1.59 procedures. These procedures
employ a bathystrophic storm surge theory to derive surge elevations induced by the
probable maximum hurricane. The theory permits calculating surge levels along an ocean
bottom transect. It is a 1-d method that cannot be applied to irregular shorelines involving
inlets, or barrier islands. The method is considered obsolete today, but it was an accepted
procedure at the time. The new storm surge methodology developed by the U.S. Army
Corps of Engineers leads to different and often appreciably lower surge levels. Therefore,
the U.S. NRC memo recommended that the existing regulatory guidance should be

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revised for use by new applicants. Revised guidance would incorporate new hurricane
data and methodologies for determining design basis flood levels at locations on the Gulf
or Atlantic coasts, and these new surge levels would be lower than what was previously
used.
In addition, a recent task force report on hurricanes indicates that the data used in
these models does not account for climate variability over longer time-scales. Oyster
Creek in New Jersey is over 2 miles from the Atlantic Ocean and the site does not
experience the full force of hurricane winds. The hurricane flood design for Oyster
Creek is based on the historical data on nine severe hurricanes which threatened the plant
site between 1935 and 1967 (Haney, 2006). This period of time coincides with hurricane
intensity and frequency that is below the norm when considering a much longer
timescale, and therefore may not provide adequate margins in design. The highest
observed water elevation was 1.37 m (4.5 ft) above mean sea level. Water level would
need to reach the plant grade level 1.83 m (6 ft) mean sea level before it would seep into
any of the Oyster Creek buildings (Haney, 2006). Similarly, the hurricane flood design
for the St. Lucie site is based on the historical data of 20 hurricanes which have
threatened the plant since 1900 (Haney, 2006).
While always a dynamic environment, when hurricanes make landfall the coastal
environment becomes hostile. Safety issues are currently the chief concern for nuclear
power plant operation at coastal locations. The sea level rise models used in this study
demonstrate that investment in shoreline and flood protection structures will be necessary
to prevent flooding of coastal nuclear power plant sites. However, shore armoring can
worsen erosion of adjacent lands and cause habitat losses, thereby impairing the ability of
human and natural systems to adapt to climate change. The next section will explore the
impacts of climate change at inland locations.

Part II Inland Climate Impacts
Similar to the coastal environment, at inland locations it is not a change in
average conditions, but rather a change in variability and extremes that is of primary
concern for vulnerability and adaptation (Burton et al., 2001). While nuclear power plants
located along the coast benefit from an ample supply of cooling water, heat waves and
drought threaten to reduce the supply of cooling water at inland locations. At the same

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time, nuclear power plants at inland locations must also contend with flooding during
storms and intense precipitation events. The first step in evaluating climate impacts to
nuclear power is to understand the changes in extremes forms of climate that will occur at
inland sites. In Chapter 5 a literature review provides details on heat waves, heavy
precipitation events, drought, and changes to aquatic ecosystems that could increase the
frequency of biological fouling of intake structures. This chapter explores the latest in
climate science by looking at historical climate records, recent changes, and modeled
predictions. Chapter 6 reviews the methods used to evaluate nuclear power at inland
sites. Chapter 7 presents the results of 1) Flooding in France, 2) Heat Waves and
Drought in France, 3) Drought and Heat Waves in the United States, and 4) Biological
Fouling in Canada and the United States.

5. Inland Climate Concerns Background
Storms are only one form of extreme weather. While the El Nino-Southern
Oscillation (ENSO) causes storms events on the California coast, it is also responsible for
both droughts and floods in regions throughout the world. The warm ocean temperatures
trigger changes in atmospheric circulation creating dry conditions in some regions and
wet conditions in others. La Niña, which follows El Niño tends to reverse the trend
causing dry periods in areas that were wet during El Niño and vice versa (K. Trenberth et
al., 2004). How climate change will impact this cycle remains uncertain. However,
results of observational studies suggest that in many areas, changes in total precipitation
are amplified at the tails, and changes in some temperature extremes have been observed.
Furthermore, models show changes in extreme events for future climates, such as
increases in extreme high temperatures, decreases in extreme low temperatures, and
increases in intense precipitation events (Easterling, 2000).
Basic theory, climate model simulations and empirical evidence all confirm that
warmer climates, owing to increased water vapor, lead to more intense precipitation
events even when the total annual precipitation is reduced slightly, and with prospects for
even stronger events when the overall precipitation amounts increase (K. E. Trenberth et
al., 2007). The warmer climate increases risks of both drought and floods but at different
times and/or places. For instance, the summer of 2002 in Europe brought widespread
floods but was followed a year later in 2003 by record-breaking heat waves and drought

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(K. E. Trenberth et al., 2007). Higher water temperatures and changes in extremes are
projected to affect water quality and exacerbate many forms of water pollution including:
sediments, nutrients, dissolved organic carbon, pathogens, pesticides, salt, and thermal
pollution (Bates et al., 2008). These impacts cause changes to the structure of aquatic
ecosystems which can in turn lead to intake fouling. Ultimately, nuclear power operation
is threatened by too much water from flooding, too hot of water from heat waves, and too
little water due to drought or intake biological fouling.

5.1. Heat Waves
Compared to other extreme weather events, heat waves typically receive little
attention. This lack of recognition increases the vulnerability of populations to heat
waves. For instance, in the United States loss of human life by hot spells in summer
exceeds that caused by all other weather events (G.A. Meehl & Tebaldi, 2004). During
the 2003 European heat wave, data provided by the Director-General of the French
Institut de Veille Sanitaire estimated an excess mortality in France of 11, 435 people
from August 1st to 15th (World Health Organization Europe, 2003), while other
estimates have been as high as 15, 000 (Lagadec, 2004; Poumadere et al., 2005). Multiday events make it more difficult to attribute the loss of life due to temperature extremes
because affected individuals often suffer from other health problems heat is sometimes
recorded as a secondary cause of death (Changnon et al., 1996). Therefore, it is
recognized that deaths due to heat waves are underestimated. This has been confirmed
by research that finds much higher death rates, by comparing death counts in summer
during heat-wave and non-heat-wave periods (Palecki et al., 2001).
Currently heat waves are more severe in the southeast United States and less
severe in the northwest United States. For Europe, there is more of a north-south gradient
in both observations and models, with more severe heat waves in the Mediterranean
region and less severe heat in the north (G.A. Meehl & Tebaldi, 2004). Many of the
areas most susceptible to heat waves in the present climate experience the greatest
increase in heat wave severity in the future; however, other areas not currently as
susceptible also experience increased heat wave severity in the 21st century models
(Diffenbaugh et al., 2005; G.A. Meehl & Tebaldi, 2004). This poses a challenge to
adaptation because these regions are not accustomed to dealing with heat waves.

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Furthermore, according to the IPCC 2007 report, it is very likely that heat waves will be
more intense, more frequent and longer lasting in a future warmer climate (G.A. Meehl et
al., 2007). Climate model simulations show increases in the intensity of heat waves of all
durations. For example, in the Great Lakes region a 1-in-20-yr event lasting 5 days has an
intensity range of between 28° and 34°C under present-day conditions. This range
becomes 38° to 44°C in response to CO2 doubling (Clark et al., 2006).
One method of quantifying changes in extremes is to calculate the frequency at
which a fixed threshold is exceeded under different CO2 levels simulations. Under
doubled CO2 conditions, the occurrence of days on which maximum temperatures exceed
the simulated present-day 99th percentile threshold were found to be 20 and 28 times
more frequent in January and July respectively (D. N. Barnett et al., 2006). The
magnitude of the increases in daily temperature extremes varies substantially with region.
In July, for example, the largest increases are found over western parts of North America,
the northern half of South America, and much of southern Europe, northern Africa and
the Middle East (D. N. Barnett et al., 2006).
Analyzing temperature distributions is a more illustrative approach to
understanding climate change. For instance, there is a tendency for increasing
temperature variability in summer and decreasing variability in winter and spring
(Scherrer et al., 2005). While significant shifts to warmer conditions occur in June, July,
and August, changes in extremely hot days are shown to be significantly larger than
changes in mean values in some regions (Clark et al., 2006). Furthermore, not all regions
show the same change in temperature distributions. Under CO2 doubling conditions, the
Czech Republic temperature distribution shifts to warmer conditions and the warm tail
extends slightly, whereas in the Great Lakes region, a shift to warmer conditions is
accompanied by a subtle change in shape with a wider distribution for temperatures and a
broader maximum peak. Eastern China and southwestern France have particularly
complex changes in distribution shape. The two regions have a bimodal distribution
under doubled CO2 with peaks at 32° and 40°C in eastern China and 25° and 40°C in
southwestern France (Clark et al., 2006).
Regional differences may be due in part to fine-scale processes that act as
feedbacks either mediating or intensifying heat waves. Soil moisture, number of wet
days, and nocturnal cooling are significant factors responsible for changes in heat wave

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intensity, duration, and frequency (Clark et al., 2006). For instance, analysis of daily
temperatures during simulated heat waves, demonstrates that increases in intensity and
frequency are explained mainly by reductions in nocturnal cooling during hot spells,
rather than by increases in daytime heating (Clark et al., 2006). Moreover, peak increases
in hot events are amplified by surface moisture feedback that appear to result from
complex, two-way interactions between large-scale atmospheric circulation and finescale spatial variability in topography, natural land cover, and human land use
(Diffenbaugh et al., 2005). Global Climate Model (GCM) simulations demonstrate that
the greatest change in return values of daily maximum temperature are found in central
and southeast North America, central and southeast Asia, and tropical Africa where there
is a substantial decrease in summertime soil moisture. Reduced soil moisture means that
maximum surface temperatures are less likely to be moderated by evaporative cooling.
In contrast, the west of North America is affected by increased precipitation resulting in
more soil moisture and a more moderate increase in extreme maximum surface
temperature (Kharin & Zwiers, 2000).
During the 2003 European heat wave, the heat leaving the dry soil contributed to
the rather rapid rise in temperature in the morning hours. Observations taken at the
University of Reading indicate that the ground played an important role in the
accumulation of heat during the day and its gradual release at night (Black et al., 2003).
This acted to offset night-time cooling driven by upward long wave radiation under clear
skies, slowing the decrease in air temperature before sunrise. For the duration of the heat
wave, the night-time temperatures exceeded the daily average temperatures (Black et al.,
2003).
A global coupled climate model shows that there is a distinct geographic pattern
to future changes in heat waves. Observations and the model show that present-day heat
waves over Europe and North America coincide with a specific atmospheric circulation
pattern that is intensified by ongoing increases in greenhouse gases, indicating that it will
produce more severe heat waves in those regions in the future (G.A. Meehl & Tebaldi,
2004). Model results suggest that under enhanced atmospheric greenhouse-gas
concentrations, summer temperatures in Europe are likely to increase by over 4˚C on
average, with a corresponding increase in the frequency of severe heat waves (Beniston,
2004). Using a threshold for mean summer temperature that was exceeded in Europe in

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2003, but in no other year since the start of the instrumental record in 1851, estimates
show that it is very likely that human influence has at least doubled the risk of a heat
wave exceeding this threshold magnitude (Stott et al., 2004). Moreover, Regional
Climate Models (RCM) simulations suggest that towards the end of the century about
every second summer could be as warm or warmer and as dry or dryer than 2003 (Schar
et al., 2004). The models demonstrate that the European summer climate might
experience a pronounced increase in year-to-year variability in response to greenhousegas forcing. Such an increase in variability might be able to explain the unusual European
summer 2003, and would strongly affect the incidence of heat waves and droughts in the
future (Schar et al., 2004).

5.2. Precipitation
Globally, the area of land classified as very dry has more than doubled since the
1970s, while at the same time the frequency of heavy precipitation events has increased
over most areas (Bates et al., 2008). It is very likely that the frequency of heavy
precipitation events will increase over most areas during the 21st century, while at the
same time the proportion of land surface in extreme drought is projected to increase
(Bates et al., 2008; Frich et al., 2002).
A warmer atmosphere has a greater moisture-holding capacity; therefore, global
climate model simulations demonstrate that extreme precipitation increases almost
everywhere. Relative changes in extreme precipitation are larger than changes in total
precipitation (Kharin & Zwiers, 2000). Over the Pacific Northwest and Gulf Coast
regions, increases in extreme-event contribution were accompanied by increases in the
frequency of dry days (Diffenbaugh et al., 2005). Similarly in Europe, increases in the
amount of precipitation that exceeds the 95th percentile is very likely despite a possible
reduction in average summer precipitation over a substantial part of the continent
(Christensen & Christensen, 2002).
The impact of climate change on precipitation is often described as a wetter
world; however, this oversimplifies the situation given that precipitation is highly
variable regionally and temporally (Bell et al., 2004). Seasonal shifts in precipitation
provide further challenges to adaptation as precipitation may increase in one season and
decrease in another (Kundzewicz et al., 2007). In a warmer world, less winter

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precipitation falls as snow and the melting of winter snow occurs earlier in spring. Even
without any changes in precipitation intensity, both of these effects lead to a shift in peak
river runoff to winter and early spring, away from summer and autumn when demand is
highest (T. P. Barnett et al., 2005). For instance, hydrological simulations suggest that
this warming will shift the Rhine River basin from a combined rainfall and snowmelt
regime to a more rainfall-dominated regime, resulting in an increase in winter discharge,
a decrease in summer discharge, increases in the frequency and amount of peak flows,
and longer and more frequent periods of low flow during the summer (T. P. Barnett et al.,
2005).
In the mid-latitudes, the pattern of precipitation intensity increase is related in
part to the increased water vapor being carried to areas of mean moisture convergence to
produce greater precipitation, as well as to changes in atmospheric circulation. Advective
effects contribute to greatest precipitation intensity increases over northwestern and
northeastern North America, northern Europe, northern Asia, the east coast of Asia,
southeastern Australia, and south-central South America (G. A. Meehl et al., 2005).
Heavy precipitation events are increasing in both frequency and intensity. Since 1910,
across the contiguous United States, precipitation has increased about 10% primarily
from heavy and extreme daily events (Karl & Knight, 1998). Furthermore, the fraction of
annual total precipitation from events wetter than the 95th percentile of wet days (≥1
mm) for 1961–1990 shows that major increases have been observed in many parts of the
USA, central Europe and southern Australia (Frich et al., 2002). Observed changes in
intense precipitation have been analyzed for over half of the land area of the globe
utilizing three climate model simulations, all with greenhouse gas concentrations
increasing during the twentieth and twenty-first centuries and doubling in the later part of
the twenty-first century. Utilizing these models changes in heavy precipitation
frequencies were found to be higher than changes in precipitation totals and, in some
regions, an increase in heavy and/or very heavy precipitation occurred while no change or
even a decrease in precipitation totals was observed (Groisman et al., 2005).
While heavy precipitation may increase in the winter, there is a tendency for
drying of the mid-continental areas during summer, indicating a greater risk of droughts
in those regions (G.A. Meehl et al., 2007). The term drought may refer to meteorological
drought (precipitation well below average), hydrological drought (low river flows and

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water levels in rivers, lakes and groundwater), agricultural drought (low soil moisture),
and environmental drought (a combination of the above) (Kundzewicz et al., 2007). The
socio-economic impacts of droughts may arise from the interaction between natural
conditions and human factors, such as changes in land use and land cover, water demand
and use (Kundzewicz et al., 2007).
Hydrological drought integrates climate factors and additional influences such as
plant transpiration, soil, and water withdrawals. Hydrological models have been used for
watersheds throughout Europe. 100-year droughts show strong increases for large areas
of southern and southeastern Europe, while typical 100-year floods are projected to occur
more frequently in large areas of northern and northeastern Europe. Some smaller
regions show indications for a rise in both flood and drought frequencies, which may be
due to a change in the seasonal variability of precipitation and temperature that leads to
both more extreme high and low-flow months (Lehner et al., 2006).
Meteorological drought in the Hadley Centre Global Climate Model is assessed
using the Palmer Drought Severity Index (PDSI). PDSI is an index of moisture supply
and demand at the land surface determined by precipitation and evapotranspiration. At
interannual time scales, for the majority of the land surface, the model captures the
observed relationship between the El Niño–Southern Oscillation and regions of relative
wetness and dryness. At decadal time scales, on a global basis, the model reproduces the
observed drying trend since 1952. This model predicts that the proportion of the land
surface in extreme drought will increase from 1% for the present day to 30% by the end
of the twenty-first century. The number of extreme and severe drought events is projected
to double. While the number of moderate drought events remains stable, there is a
significant increase in the mean event duration for all forms of drought (Burke et al.,
2006).
Causal factors of natural droughts are not well understood and are complicated
by multiple feedback loops. In general, the underlying cause of a drought is a change in
average atmospheric circulation patterns, which can result from both internal and external
forcings. Internal forcings include sea-surface temperature (SST) and land-surface
characteristics, whereas external forcings include the sun, the Earth's orbit , and
volcanoes (K. Trenberth et al., 2004). Historical documents, tree rings, archaeological
remains, lake sediment, and geomorphic data provide evidence that several droughts in

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North American in the last 2000 years were worse than those of the twentieth century,
including the droughts of the 1930s and 1950s. Furthermore, paleoclimatic data suggest a
1930s-magnitude Dust Bowl drought occurred once or twice a century over the past 300400 years, and a decadal-length drought once every 500 years (Woodhouse & Overpeck,
1998). In the United States, three distinct periods of widespread and persistent drought
stand out in these records for the latter half of the nineteenth century: 1856-1865, 18701877 and 1890-1896. Each of these events is shown to coincide with the existence of a
cool, La Nina-like tropical Pacific (Herweijer et al., 2006). It is found that the correlation
between modeled and observed soil moisture variability in the Plains region decreases
from the nineteenth century to the twentieth century, indicating drought conditions that
are forced more by sea-surface temperature in the earlier period. In the twentieth century,
internal atmospheric variability and external forcing from anthropogenic changes in land
use, atmospheric composition or solar variability had a larger influence on the drought
variability in the Plains (Herweijer et al., 2006). Drought reconstructions reveal the
existence of successive mega-droughts persisting for twenty to forty years, but similar in
year-to-year severity and spatial distribution to the major droughts experienced in today’s
North America. These mega-droughts occurred during a 400-yr-long period in the early
to middle second millennium A.D., with a climate varying as today’s, but around a drier
mean. The implication is that the mechanism forcing persistent drought in the West and
the Plains in the instrumental era is comparable to that underlying the mega-droughts of
the medieval period (Herweijer et al., 2007). However, the cause of historic drought is
not fully understood. Models agree that tropical Pacific SSTs are important for North
American drought, but the models disagree on the relative roles of Pacific, Indian, and
Atlantic SST forcing (Herweijer et al., 2007).
The causes and global context of the North American drought between 1998 and
2004 were examined using atmosphere model simulations variously forced by global
SSTs or tropical Pacific SSTs alone. The drought divides into two distinct time intervals.
Between 1998 and 2002 it coincided with a persistent La Niña–like state in the tropical
Pacific. During the later period of the drought, from 2002 to 2004, weak El Niño
conditions prevailed and, while the global climate adjusted accordingly, western North
America remained in drought. The climate models did not simulate the continuation of
the drought in these years, suggesting that the termination of the drought was largely

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unpredictable in terms of global ocean conditions (Seager, 2007). Sea-surface
temperature is not the main driver for all droughts particularly in certain regions. For
instance, summer season precipitation variability in the Southeast United States appears
governed by purely internal atmospheric variability; therefore, model simulations forced
by historical SSTs are very limited in their ability to reproduce the instrumental record of
precipitation variability in the southern United States (Seager et al., Submitted).
In the Southeast region, tree ring records show a two decade long drought in the
mid Sixteenth Century, a long period of dry conditions in the early to mid Nineteenth
Century, and that the Southeast was also impacted by some of the Medieval megadroughts centered in western North America (Seager et al., Submitted). Climate model
projections predict that in the near term future precipitation in the Southeast will increase,
but evaporation will increase more. According to these projections climate change will
not end the Southeast’s water problems and is likely to make the problem worse (Seager
et al., Submitted).
Current demands for water in many parts of the world will not be met under
plausible future climate conditions, much less the demands of a larger population and a
larger economy (T. P. Barnett et al., 2005). The recent two year drought that struck the
Southeast, by summer and fall 2007, had caused serious water shortages in the region
leading to the imposition of restrictions on water use and the opening up of legal conflicts
within and between states on the regulation and use of the region’s water resources. This
is despite the most recent two year drought not being more severe than earlier droughts,
including one as recently as 1998 to 2002, and indicates that the water shortage crisis was
largely driven by rising demand (Seager et al., Submitted). Currently, human beings and
natural ecosystems in many river basins suffer from a lack of water. In global-scale
assessments, basins with water stress are defined either as having a per capita water
availability below 1,000m3/yr (based on long-term average runoff) or as having a ratio of
withdrawals to long-term average annual runoff above 0.4. These basins are located in
Africa, the Mediterranean region, the Near East, South Asia, Northern China, Australia,
the USA, Mexico, north-eastern Brazil, and the western coast of South America
(Kundzewicz et al., 2007).
Responses to climate change must be resolved at regional and local levels in
order for effective action to be taken; therefore, it is important to assess the potential for

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climate change on a regional level (Bell et al., 2004). The gap between global climate
modeling and local to regional applications is filled by statistical and dynamical
downscaling, which utilize statistical relationships between large-scale circulation and
regional climate models to derive regional climate information (Leung et al., 2003).
Regional models are also valuable when dealing with impacts to aquatic ecosystems and
local resources.

5.3. Water Quality and Aquatic Ecosystems
The interaction between climate change, land use, and other environmental
problems must be considered when evaluating climate impacts. Changes in runoff
patterns and water temperature pose water quality problems and can alter aquatic
ecosystems. For instance, increases in summer water temperature can increase oxygen
depletion in thermally stratified lakes, increase the rate of nutrient and contaminant
releases from lake-bottom sediments, and cause algal blooms that restructure the aquatic
food web (Bates et al., 2008; Kling et al., 2003).
Changes to aquatic ecosystems and water quality issues are a problem in many
regions. The green filamentous alga, Cladophora, in the Great Lakes is an example of
this problem. Control of Cladophora was achieved in the 1980s through programs that
reduced runoff pollution and improved sewage treatment. In the latter part of the 1990’s,
excessive Cladophora growth reemerged as a problem in the Great Lakes (Ontario Power
Generation, 2007). Climate change and the introduction of zebra mussels to the Great
Lakes caused the problem to return.
Zebra mussels promote Cladophora growth through several mechanisms.
Cladophora grow on rocky substrates, and the zebra mussel beds provide additional
substrate for the algae to grow (Hecky et al., 2004). The feces from the zebra mussels
provide new sources of available phosphorous for the algae, without requiring any
increase in external phosphorous to the lakes. The filter-feeding zebra mussels improve
the clarity of the water column; thereby, increasing the amount of light that reaches the
growing Cladophora (Hecky et al., 2004; Ontario Power Generation, 2007; S. A.
Reynolds, 2004). In addition, positive feedback occurs when the decomposition of the
increased biomass of Cladophora causes oxygen depletion that leads to further release of
phosphorous from sediments (Hecky et al., 2004).

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Climate change affects Cladophora in several important ways. First, higher
water temperatures and corresponding oxygen depletion cause the release of nutrients
from sediment. Regression analysis demonstrates that significant changes have already
occurred in the Great Lakes including a lengthening of the duration of summer
stratification and an earlier transition to spring-like conditions (McCormick &
Fahnenstiel, 1999). In addition, model projections indicate further increases in water
temperatures, longer duration of warm water stratification, a shallower depth of warming
and more extensive depletion of oxygen from deep waters (Lehman, 2002). Second,
excessive Cladophora production has coincided with periods of low lake levels, both
now and in the 1960s (Harris, 2008). Many assessments project lower net basin supplies
and water levels for the Great Lakes–St. Lawrence Basin (Bates et al., 2008; Mortsch et
al., 2000). Lower lake levels are due to decreased precipitation in this region (Mortsch et
al., 2000), and greater evaporation from open water due to reduced ice cover (Kling et al.,
2003).
Finally, climate plays a role in the detachment of Cladophora and seasonal
biomass accrual. In terms of nuclear power plant operation, Cladophora growth in itself
is not a concern, the real problem occurs after the algae detach from rocky substrate.
Typically, growth is renewed in the spring when water temperature reaches 5˚C and
attains its greatest development at 18˚C. The mass of filaments detaches and follows
currents until it reaches the shore or is carried into deep water. New growth from the
remaining stubs results in smaller summer population, while lower autumn temperatures
result in another algal bloom which detaches as water temperatures decline toward 5˚C
(Taft, 1975). Experimental evidence indicates that filaments are generally weaker when
temperatures are close to the upper tolerance levels 25˚C(77˚F) (Storr & Sweeney, 1971).
The weakened filaments cause the algae to detach from the substrate. Lester et al. (1988)
found in lab studies the optimum temperature for Cladophora was between 28 and 31˚C.
They found no evidence for a decline in photosynthetic rate with increasing temperature
for this range of temperatures and high temperatures are not a likely physiological
explanation of mid-season dieback (Lester et al., 1988). Higgins et al. (2006) attribute
the dieback to self-shading exacerbated by moderately high water temperatures (~23°C).
Dense mats of Cladophora at the water surface block light, thereby inducing negative
growth rates and deterioration at the base of the mat (Higgins et al., 2006). A growth

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model for Cladophora predicts an earlier spring growth with increasing surface water
temperatures, but only a marginal increase in peak Cladophora biomass (Malkin et al.,
2008). However, self-shading and temperature are not the only mechanisms responsible
for detachment. Large storm events can cause a large synchronous detachment of
Cladophora. One consequence of a massive detachment event is an increase in irradiance
and nutrient concentrations relative to the remaining Cladophora filaments, potentially
serving to enhance growth. Furthermore, climate driven detachment events could affect
total seasonal biomass accrual (Malkin et al., 2008). The detachment events combined
with new algae growth could result in an increase in the frequency of biological fouling
events at nuclear power plants.
The reemergence of the Cladophora problem demonstrates that the impacts of
climate change are being felt now. In addition, evidence confirms that heat waves,
drought and heavy precipitation events are increasing. The next section explores
methods that evaluate how nuclear power has been adapting to these changes in climate.

6. Inland Methods
The inland portion focuses on how nuclear power plant operations deal with
current climate variability. The countries studied in this section, France, the United
States, and Canada, are currently constructing or planning to construct new nuclear
reactors. It is necessary to look at nuclear reactor operation in these countries in order to
get an understanding of the scope of the problem climate change poses.
France is the country with the highest dependence on nuclear power, generating
over 75% of its electricity from nuclear in addition to being the world’s largest net
exporter of electricity (World Nuclear Association, 2008c). France was selected to
understand the consequences of having a high dependence on nuclear power and because
recently the country’s nuclear fleet has encountered problems with both flooding and
widespread heat waves at inland locations. France has 15 inland nuclear power plant
sites with 44 operating reactors. The consequences of flooding to safe operations are
evaluated, and the steps taken and costs to upgrade flood protection at inland locations in
France are reviewed. In addition, all reactors at inland sites are included in the analysis
for impacts felt during recent heat waves.
Almost 20% of the electricity generated in the United States comes from nuclear

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power and with 104 operating reactors the U.S. has the largest fleet of nuclear reactors in
the world (World Nuclear Association, 2008d). The geographical extent provides an
opportunity to look at the regional issues that arise from electing to use nuclear power.
For instance, nuclear power plants located along rivers that depend on cool water from
mountain reservoirs encounter different problems compared to reactors that are located
along large lakes. Figure 28 shows the distribution of nuclear power plants in the United
States.
The heat waves and drought section reviews sites throughout the United States
that were affected by the 1988 heat wave, the impact of a reduced mountain snow pack
on nuclear power plants in the Midwest (Region IV), and the drought and water scarcity
problems in the Southeast (Region II). Nuclear power plants located along the Great
Lakes in the U.S. (Region I and III) and Canada (Province of Ontario) have to deal with a
specific problem: biological fouling from the green algae Cladophora. Analysis of the
situation provides an opportunity to see how two different countries with different reactor
types address the same problem. Canada receives 18% of its energy from nuclear power;
however, the province of Ontario generates 50% of its electricity from nuclear power
(World Nuclear Association, 2008a).

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Figure 28. Nuclear power plants currently operating in the United States (U.S. Nuclear
Regulatory Commission, 2008d).

The criteria described in Chapter 1 are used to judge the actions taken to adapt
nuclear power plant operations to flooding, drought, heat waves, and biological fouling.
Several indicators are used to gauge these criteria as outlined in Table 30.
Table 30. Criteria and indicators used to evaluate nuclear power plants located at inland
sites.
Criteria
Indicator
Interrupted Operation
Unplanned shutdowns, power reductions
Financial Costs
Intake adjustments
Alteration of cooling systems
Flood protection
Adaptation Impairment - Human Systems Legal Battles (pertaining to water)
Brownouts/Blackouts (heat waves)
Adaptation Impairment - Natural Systems Thermal pollution
Other Environmental Problems
Safety problems that include:
Loss of off-site power
Communication failure
Restriction of evacuation routes
Equipment malfunction
Unplanned shutdowns

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Reports generated by nuclear regulatory agencies, the Autorité de Sûreté
Nucléaire (ASN) in France, the Nuclear Regulatory Commission in the U.S. (U.S. NRC),
and the Canadian Nuclear Safety Commission (CNSC) in Canada, provides the
information on length of reactor shutdown and safety issues arising from climate impacts.
Utility reports and industry journals provide information concerning: the financial costs
of adapting to climate, revenue losses from shut-downs, and changes to operating
procedures such as temporary suspension of environmental regulations. Court documents
that detail the legal battles pertaining to water, in regions with nuclear power plants,
provide evidence of the reduced ability of human systems to adapt to climate change.

7. Inland Results
7.1. Flooding of Nuclear Power Plants in France
Inland reactors are threatened by flooding due to storms that reach inland and
intense precipitation events. Reactors in France were impacted by floods during the
winter of 2003; however, this was not the first time flooding has affected reactors in the
country. It became apparent after the 1999 flood of the Le Blayais site that flood
protection had to be investigated and improved at many sites.
Le Blayais nuclear power plant site consists of four 900 MW(e) pressurized
water reactors (PWR) located 30 km southeast of the Atlantic ocean, on the banks of the
Gironde estuary, in a swampy area. The Design Basis Flood (DBF) used to design dykes
is 5.02 m French national datum level (NGF). The DBF was calculated as the level of
water resulting from the maximum astronomical tide and the 1000 year storm surge. The
site is surrounded by a dyke made of earth and protected on the River Gironde side by a
pile of stone blocks (IAEA, 2003b). Alongside the River Gironde, its height is 5.2 m
above the national datum, and its height is 4.75 m at the sides. The flooding event that
occurred on December 27th,1999 resulted from a high tide, wind speeds of 100 km/h that
generated waves estimated to reach a height of 2 m, combined with a 2.01 m storm surge.
The maximum storm surge measured prior to December 27th, 1999 was 1.20 m for a 40
year historical series of data. Investigations carried out on the site after the storm showed
that the water had overtaken obstacles from 5 to 5.30 m (Gorbatchev et al., 2000; IAEA,
2003b). According to the information provided by the nuclear operator, flooding began

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approximately two hours before high tide at around 7:30 pm on December 27th 1999
(Gorbatchev et al., 2000).
Loss of auxiliary power supplies and loss of the 400 kV grid for Units 2 and 4
occurred during the storm. Attempts to switch the units to house load operation to enable
them to continue powering their auxiliaries following disconnection of the grid failed
causing Units 2 and 4 to shutdown. The diesel generators of both units started up and
operated correctly. The 400 kV line powering Units 1 and 3 continued to be unavailable.
This led to the shut down of all 3 operating units. Meanwhile, strong waves submerged
the plant platform, with water entering mainly on the northwest side of the dyke. The
waves moved the rocks, protecting the dyke, and part of it was washed away alongside
the River Gironde. The water reached a depth of around 30 cm in the northwest corner of
the site (Gorbatchev et al., 2000; IAEA, 2003b). The volume of water which came into
the facilities has been estimated to be about 90,000 m3 (IAEA, 2003b). Units 1 and 2
were severely affected by incoming water: one of the essential service water pumps was
lost as a result of immersion of the motors, some utility galleries were flooded, some
rooms containing outgoing electrical feeders were flooded and electrical switchboards
made unavailable, the bottom of the fuel building of Units 1 and 2 was also flooded
(Gorbatchev et al., 2000).
After continuously monitoring the repair work for the three days following the
incident, the Safety Authority asked EDF to repair all the flooded equipment and to
upgrade the plant’s protection against flooding. The dyke around the nuclear site was
raised by 1 meter and the site was equipped with an alert system based on meteorological
forecasts from Météo-France. An operational procedure was designed to bring the site
reactors to a safe state and protect the premises felt to be most important. Under these
conditions, the Nuclear Safety Authority authorized the two reactors most severely
affected by the flood to restart in May 2000 (Autorité de sûreté nucléaire, 2000). The
Safety Authority (ASN) also asked Électricité de France (EDF) to take steps against the
risk of flooding due to surging of the Gironde River, before the first quarter of 2001. EDF
in September 2000 proposed an anti-surge device consisting of riprap and a wall placed
on top of the existing dyke that had already been raised in March 2000. The stability of
this arrangement was examined by the Institute of Radiological Protection and Nuclear
Safety (IPSN) and the Nuclear Installation Safety Directorate (DSIN), which approved its

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implementation. The height of the wall, determined following hydrodynamic modeling of
the Gironde estuary and testing in a surge channel, was raised to 8.50 meters at the
request of the Nuclear Safety Authority (Autorité de sûreté nucléaire, 2000).
The flooding which occurred at Le Blayais Nuclear Power Plant revealed a
potential mode by which the safety of all the units of a single plant could be jeopardized
(Gorbatchev et al., 2000). Inspection of the site revealed: that the operating teams were
unprepared to deal with an incident that affected all the reactors on a site; that it was hard
to perceive storm-related phenomena from the data available in the control room; and that
the site had no suitable control procedures for managing a situation involving loss of
outside electrical power sources combined with flooding (Autorité de sûreté nucléaire,
2000). The ASN wanted to take full advantage of the lessons learned from the flooding of
Le Blayais and improve protection of all the reactors in France against flooding. In
March 2000, the ASN asked EDF to produce an inventory of the existing constructive,
material and organizational measures for dealing with the arrival of water on all of EDF’s
nuclear sites. On the basis of historical river flood data and of tides and storm surges for
coastal areas, this exercise consists in determining the height of water opposite the
nuclear site, with a return period of 1000 years. The DSIN asked EDF to propose
protection measures such as dykes, curbs, alert systems, for DSIN to examine and
validate prior to implementation (Autorité de sûreté nucléaire, 2000).
However, DSIN told EDF it must not wait to act until revised calculations of
maximum flood risk are completed, and that it must take measures to protect reactor sites
from external floods as soon as possible (MacLachlan, 2001). Action was particularly
urgent at the Belleville PWR site, where EDF studies showed the ''safe'' flood level
equivalent to the level of the maximum historical flood with a 15% safety margin was up
to 1.4 meters higher than the level assumed in the plant's design (MacLachlan, 2001). In
addition, protection of installations on the Tricastin site are particularly complicated to
manage due to the large number of facilities and the proximity of the Rhone and the
Rhone canal (MacLachlan, 2003d). DSIN asked EDF to advise it by June 9, 2001 what
measures have been or will be taken to adapt the site's protections to the new data. A
subsequent study by safety experts at IPSN showed that many EDF sites, as well as other
French nuclear sites were under protected. The studies also focused on other external
risks that might not have been sufficiently taken into consideration in original design

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(MacLachlan, 2001). EDF announced May 16th that it had proposed a 100-million-franc
(approximately 13.5 million USD) program to build a levee around the Belleville site, to
raise flood protection by roughly one meter. In the meantime, EDF planned to reinforce
the site's system of mobile flood protection walls (MacLachlan, 2001).
The 1999 flooding was the first time the emergency center was activated by
ASN. The same actions were necessary on the morning of December 2nd 2003. The
Cruas nuclear power plant takes its cooling water from the Rhone River. During the night
of December 1st and 2nd 2003, intake of water containing large amounts of mud and
vegetable matter impaired the efficiency of the cooling systems. Degradation of the heat
sink according to normal operating procedures requires reactor shutdown. This state is
referred to as the safe shutdown state. Loss of the heat sink requires initiation of the onsite emergency plan. The rapid deterioration of the exchange capacity of the cooling
systems led the Cruas plant operator to trigger the on-site emergency plan as a preventive
measure. The Tricastin plant, located further downstream than Cruas, takes its cooling
water from the Rhone bypass canal at Donzère. Pumping of water containing large of
amounts of vegetable matter and mud triggered safety shutdown of the cooling water
pumping system and consequently automatic shutdown of the 3rd and 4th reactors on the
2nd and 3rd of December 2003 respectively (Autorité de sûreté nucléaire, 2003a). Fearing
a deterioration of the situation, the Tricastin plant triggered its own emergency plan on
the night of December 2nd 2003. Late afternoon on December 3rd 2003, the status of the
nuclear installations, the weather forecast and the flow rate of the Rhone river were
considered to be satisfactory enabling a number of alerts to be lifted and the gradual
restart of reactors (Autorité de sûreté nucléaire, 2003a).
Lessons learned from 1999 flood were applied during the 2003 event. EDF head
office services maintained a supervisory team in action in order to monitor the changing
situation in the Rhone valley and in the Loire (Belleville, Dampierre, Saint-Laurent and
Chinon) and Garonne (Golfech) valleys days before the maximum flood levels were to be
reached on the rivers (Autorité de sûreté nucléaire, 2003a). In accordance with their
procedures, the operators of the nuclear power plants on the Loire took preventive
protection measures, in particular with regard to site access problems due to submersion
of access roads and flooding of car parks. Furthermore, the build-up of detritus in the
hydroelectric dam upstream of the Golfech plant was released in collaboration with the

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Golfech plant operator (Autorité de sûreté nucléaire, 2003a). The 2003 floods
demonstrated that some of the measures implemented after the storm of 1999 worked, but
the increasing frequency of extreme weather conditions posed the question of whether
further measures should be taken to protect nuclear installations (MacLachlan, 2003a).
The 2003 floods revealed another problem: the safety of certain installations
during flooding events depends to a large extent on the behavior of the off-site structures
not belonging to EDF. This is particularly important for the Cruas and Tricastin nuclear
power plants. Evaluating the robustness and the surveillance and upkeep of these
structures entails a decision-making process between the stakeholders, the authorities and
EDF that is in principle highly complex. Therefore, ASN asked EDF to continue the
exchanges initiated between the licensees of these structures and to keep it informed of
any difficulties (Autorité de sûreté nucléaire, 2007).
ASN is taking part in updating the IAEA guide concerning the off-site flooding
risk for nuclear sites. The objectives of this work are to create a single guide that can be
used at all nuclear installations and includes feedback from operating experience and
climate change studies. Current plans are for this guide to be published in February 2010
(Autorité de sûreté nucléaire, 2007).

7.2. Heat Waves and Drought in France
Many of the reactors that were affected by flooding in December 2003 were
impacted by heat waves the previous summer. During the 2003 summer, a combination
of low water levels and rising river temperatures, unmatched during previous heat waves,
left the country's electricity supply situation very tight (Parey & Aelbrecht, 2005). The
heat wave was also exceptional in its spatial extent. During July and August 2003,
significantly above-average temperatures were observed throughout Europe, Scandinavia,
and western Russia, with monthly mean temperatures exceeding the 90th percentile in
each region (World Health Organization Europe, 2003). The meteorological conditions
observed during the summer of 2003 raised the temperature of certain watercourses 5°C
above the mean historical values observed during the past 25 years (Autorité de sûreté
nucléaire, 2003b). Material and facilities at some nuclear power plants were potentially
threatened by the increase in air temperature. Significant loss of power was already a
problem prior to the heat wave due to constraints on thermal releases. River temperature

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forecasting depicted a critical situation from the 10th to the 20th of August with
downstream water release temperature limits forecasted or observed upstream (Parey &
Aelbrecht, 2005).
In order to comply with regulation, operators reduced power or halted production
from several of their reactors, on the Le Blayais, Golfech, Tricastin and Bugey sites
(Autorité de sûreté nucléaire, 2003a). The weekly voluntary nuclear power reduction was
between 3500 to 6000 MW during the month of August. The total power reduction
during the summer of 2003 was 5.3 TWh: equivalent to a loss of more than 200 reactor
days (Parey & Aelbrecht, 2005). EDF attempted to balance production throughout its
system by stopping certain units at certain plants rather than shutting entire multiple unit
stations (Hibbs, 2003). Black-outs and brown-outs were avoided by exercising several
options including: the purchase of energy on the wholesale power market (2800 MW),
citizenship conservation (300 MW), negotiating lower loads from industry consumers
(1700 MW) and reducing exportation to Italy (Parey & Aelbrecht, 2005). EDF was tied
to firm export contracts and the contract with Italy was the only contract with a clause
allowing interruption in the event of an emergency; nonetheless, EDF was able to cut its
power exports by more than half (Hibbs, 2003; Poumadere et al., 2005). Electricity
production and distribution hampered by the heat wave throughout Europe made energy
supply much below demand; as a result, purchasing energy on the wholesale power
market was a great expense to EDF. From August 10th to the 13th power prices were as
high as a 1000 euros/MWh, a factor of 100 higher than normal prices (Hibbs, 2003; Parey
& Aelbrecht, 2005).
Technical measures and operational changes also helped keep facilities operating.
In order to optimize management of the cooling capacity of the cold source, the operators
increased monitoring of the efficiency of those devices exchanging heat with this cold
source. The building's ventilation system at Fessenheim-1 is connected to the cooling
system and is less efficient than those at later French nuclear plants, which are connected
to the raw water system. Technical specifications require the atmosphere inside
containment to remain below 50˚C. The temperature reached 48.2˚C on July 31st, so EDF
tested a system in which the outside of containment building was sprayed using
groundwater. This system was proved to be ineffective when after four days the temp
was still at 48.7˚C (Autorité de sûreté nucléaire, 2003a; Hibbs, 2003). Due to the

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temperature rise inside the reactor buildings on the Dampierre, Chooz, and Fessenheim
sites, a waiver to the general operating rules was granted, so that a special air mixing
system could be used inside the reactor buildings (Autorité de sûreté nucléaire, 2003b).
The use of groundwater to cool the containment structure at Fessenheim was
contentious, but it was not the only unpopular decision made during the heat wave. In
July 2003, the director of nuclear safety considered that the requests submitted by the
operators of the Golfech, Tricastin and Bugey nuclear power plants, for thermal releases
in excess of those authorized by the plants’ release licenses, were non-significant
modifications and therefore approved them (Autorité de sûreté nucléaire, 2003a). For
those operator requests considered as significant, the Ministers for the Environment,
Health and Industry issued an order on August 12th 2003, authorizing electricity
production facilities located on the Rhone, Moselle, Garonne and Seine rivers to continue
operating with thermal releases higher than the limits, while limiting the temperature rise
in these watercourses to between 1 and 3 °C depending on the type of facility and the
river. However, instead of an absolute maximum temperature the new order considered
relative temperature or the difference between temperatures upstream and downstream of
the plants. Initially, EDF had asked to increase the maximum temperature of the rivers
downstream of the plants by around 1˚C (MacLachlan, 2003b).
The introduction of the order stated the rationale for its issuance. It was deemed
that the climatic conditions faced by France and Europe during the summer of 2003 were
exceptional circumstances threatening the safety of property and persons, the continuity
of public services and the economic activity of the country. The order consisted of five
articles with the first article pertained to the new thermal limits. Thermal electricity
production (fossil fuel and nuclear) facilities discharging water into the Garonne, Rhone,
Seine and Moselle river basins may continue to do so until such time as the difference
between the water temperature measured upstream and downstream after mixing each of
these installations is equivalent to 1 °C for installations fully equipped with cooling
towers, 1.5 °C for those located on the Seine and Moselle rivers, and 3 °C for the other
plants. In addition, the second article states that the use of these measures will be
reduced whenever possible and limited only to the electricity production necessary for
meeting national consumption and for complying with international agreements. The
third and fourth articles pertain to monitoring of environmental impacts to river fauna and

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human health. The electricity producers shall closely monitor the environmental impact
on river fauna and human health throughout the period in which the order is in force; in
addition, they must keep the Director General for Nuclear Safety and Radiation
Protection, the Director for the Prevention of Pollution and Risks and the Director for
Water, and the Prefects with responsibility for river basin coordination, informed on a
daily basis of the effective temperatures recorded after mixing downstream of each of the
plants concerned, along with any repercussions observed on fish life. The order ended on
September 30th 2003 (Autorité de sûreté nucléaire, 2003a).
Five power plants out of 13 that were exempted from thermal discharge limits
used the exemptions. Of those five power plants, four were nuclear: Tricastin, Bugey,
Gofech, and Cattenom as shown in Table 25. Tricastin consistently discharged water into
the Rhone River at 2˚C or more above upstream temperatures between August 14th and
August 27th. Bugey used it twice while Golfech used it 12 times (MacLachlan, 2004).
Golfech heated the Garonne by 0.4˚C to 0.8˚C, potentially significant since, the Garonne
is already one of France's hottest rivers (MacLachlan, 2003c).

Table 31. France’s inland reactors and sites issued thermal release waivers.
Site Name (# units)
Cooling Series
Waiver Waiver Waiver
Source
2003
Used? 2006
Le Blayais (4)
Garonne CP1
3 ˚C
No
3 ˚C
Bugey (4)
Rhône
CP0
3 ˚C
Yes
3 ˚C
Belleville (2)
Loire
P'4
NA
NA
NA
Cattenom (4)
Moselle
P'4
1.5˚C
Yes
1.5˚C
Chinon (4)
Loire
CP2
NA
NA
NA
Chooz (2)
Meuse
N4 series NA
NA
1.5˚C
Civaux (2)
Vienne
N4 series NA
NA
NA
Cruas-Meysse (4)
Rhône
CP2
1˚C
No
NA
Dampierre-en-Burly (4)
Loire
CP1
NA
NA
NA
Fessenheim (2)
Rhine
CP0
NA
NA
NA
Golfech (2)
Garonne P'4
1˚C
Yes
0.3˚C
Nogent-sur-Seine (2)
Seine
P'4
1.5˚C
No
1.5˚C
Saint-Alban (2)
Rhône
P4
3 ˚C
No
3 ˚C
Saint-Laurent-des-Eaux (2)
Loire
CP2
NA
NA
NA
Rhône
CP1
3 ˚C
Yes
3 ˚C
. Tricastin (4)

These measures were criticized by environmentalists and led many to wonder
whether waivers for thermal discharges would become a regular summer feature if the
July-August heat wave is indicative of climate change on a western European scale
(MacLachlan, 2003b). The following summer DGSNR issued a permanent order allowing

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EDF to modify thermal discharge limits by 1˚C to 2˚C at the Bugey, Golfech and Nogent
reactor sites and by up to 3˚C at Tricastin between July 1st and September 30th of each
year. The order requires EDF to justify discharging the hotter effluents into the rivers by
the explicit needs of the national grid or of the Eurodif gaseous diffusion enrichment
plant. The permanent order also imposed additional measures including increased
monitoring of plant systems and the environment. The order helped during the summer
of 2005, although production at Tricastin had to be temporarily lowered due to high
temperatures in late June (MacLachlan, 2005b). EDF had also used the 2003 experience
to license higher temperature limits for some nuclear plant rooms and cooling ponds
(MacLachlan et al., 2006). However, these measures were not sufficient during the 2006
heat wave.
During the 2006 heat wave, temperatures in central and western Europe were 7˚C
above historical maximums (MacLachlan et al., 2006). Black-outs were avoided by
taking actions much the same as the measures implemented in 2003. EDF bought power
on the European market and as a preventative measure purchased approximately 2,000
MW on the wholesale market prior to the heat wave (MacLachlan et al., 2006). Nuclear
power plant maintenance outages were postponed, EDF used the right it has in some
contracts to interrupt supply, and customers were asked to conserve. French power
demand was about 3% higher than historical levels for the month of July.
The Institute of Radiological Protection and Nuclear Safety (IRSN) determined
that the high temperatures had not posed any safety risk at France's nuclear installations;
however, the temperatures were close to the design limits of certain equipment important
for safety demonstration. In addition, the Loire River was the only French river with
nuclear plants where temperatures had reached limits in the operating rules set by EDF
and approved by safety authorities (MacLachlan et al., 2006). The high temperatures
were determined to be compatible with the operation of Belleville, Dampierre, St.
Laurent and Chinon; moreover, the 12 reactor units at those sites were monitored daily
during the 2006 heat wave (MacLachlan et al., 2006).
The French government published an executive order on July 22nd 2006 allowing
EDF to raise river water temperatures downstream of all its riverine nuclear plants if
necessary to preserve the stability of the national grid and maintain power supply
(MacLachlan et al., 2006). The ministerial order, valid until September 30, was signed by

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the ministers responsible for industry, environment and health. The order concerns plants
located on the Garonne, Rhone, Seine, Meuse and Moselle Rivers, at sites that host 28 of
EDF's 58 power reactors. The order doesn't specify absolute temperatures for each river
downstream of power plants, as the 2004 order did, but only the acceptable change
between the temperatures of river water at plant intake and discharge stations. The order
allows a change in temperature of 0.3˚C for Golfech on the Garonne, 1˚C for plants
equipped with cooling towers along the Rhone, and 1.5˚C for plants on the Meuse,
Moselle and Seine. Those without cooling towers, like Tricastin and Saint Alban, can
discharge water 3˚C hotter than the intake temperature. The nuclear plants on the
Garonne (Golfech) and on the Rhone (Tricastin, St. Alban, Cruas, Bugey), whose
production is necessary to balance electricity demand and supply were already operating
under the limits set in 2004 (MacLachlan et al., 2006). The 2004 order had allowed EDF
to discharge thermal effluents from Golfech into the Garonne up to a downstream
temperature of 32˚C (89.6˚F). By mid-July the Garonne was already so hot that EDF had
no margin for discharges. The 2004 order allowed discharge from Tricastin to heat the
Rhone up to 29˚C (84.2˚F), but during the heat wave the Rhone was already at 29˚C
upstream of the nuclear plant site (MacLachlan et al., 2006).
Further relaxation of thermal discharge limits was dependent on EDF accepting
three conditions. First, EDF must show an imperative necessity of keeping a given plant
on line, by proving it's needed to maintain grid stability. Second, the allowed temperature
increase was lower than what EDF had requested, for example 0.3 degrees for the
Garonne compared to 1 degree requested by EDF. Finally, the ministry asked EDF to
release water from dams upstream of Golfech, for the benefit of aquatic species. An
additional clause requires EDF and the French government to inform Belgium and
Germany, which are downstream of France on the Meuse and the Moselle Rivers, before
the utility makes use of the temperature exemptions (MacLachlan et al., 2006).
Fortunately, the authorization was unnecessary as none of the reactors utilized the 2006
waiver (Autorité de sûreté nucléaire, 2006). Regardless many actions taken in 2006 were
repeats of 2003 despite the benefit of prior experience. The rivers on which the nuclear
plants sit were already at or near the normal limit of 28˚C during the heat waves, making
it difficult for the plants to comply with discharge limits even if their cooling water isn't
excessively warm (Hibbs, 2003).

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An exceptional thermal release monitoring committee was set up to supervise the
impact of thermal releases on the watercourses. From the environmental viewpoint, the
limits stipulated in the orders aim to prevent changes to aquatic life, and ensure
acceptable health conditions if water intake for human consumption takes place
downstream. These limits may differ according to the environment and the technical
characteristics of each plant (Autorité de sûreté nucléaire, 2004). No exceptional fish
mortality was observed downstream of the nuclear power plants following the 2003 heat
wave which was thought to be due to the differences in temperature during day and night
or because fish were able to find deep cooler waters (Autorité de sûreté nucléaire, 2004;
MacLachlan, 2003c). In addition to fish mortality, no specific impact on ecosystems was
found to have occurred in the vicinity of plants as determined by oxygen concentration
and algae development (Parey & Aelbrecht, 2005). However, the ASN felt that caution
was important regarding the long-term effects on the aquatic life (Autorité de sûreté
nucléaire, 2004).
In 2003, 17 events concerned release temperature overshoots, most of which
were linked to the summer heat wave. Bugey in particular had trouble with release
temperatures during the heat wave of summer 2003 (Autorité de sûreté nucléaire, 2003a).
The decision to base thermal limits on relative temperature change in particular raised
criticism from environmental groups. Furthermore, a note published by the environment
ministry in 1999 stated that large fish begin to leave the area around the Bugey nuclear
station when the Rhone reaches 25˚C and that at a river temperature of 29˚C certain
species collapse (Hibbs, 2003). Large fish run the risk of asphyxiation in water over
27˚C, but generally leave the area if it gets too hot for them. Several important
waterways including the Garonne reached 31˚C during the 2003 summer (MacLachlan,
2003b).
The effects of the heat wave may not be obvious or immediately apparent. Most
ecological studies look at gradual increase in temperature; however, Mouthon &
Daufresne (2006) evaluated the ecological consequences of the European 2003 heat wave
based on real long-term data. They found a significant progressive change in the mollusc
community structure of the Saone upstream of Lyon during the period from September
1996 to July 2003 probably due to increasing temperature over the same period.
Moreover, a sudden change in the structure of mollusc communities occurred during the

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2003 heat wave with a significant decrease of species richness and density of gastropods
and bivalves. During 2004, mollusc density remained dramatically low. Similar
observations were performed at four other sites along the Saone and in the lower reaches
of its two main tributaries. These findings suggest that the resilience of the mollusc
populations to the heat wave is low. If the frequency of heat waves increase, as predicted
by climate models, more than half the mollusc species currently inhabiting the Saone,
Doubs and Ognon, and likely other large rivers in France may be directly threatened with
extinction (Mouthon & Daufresne, 2006).
While the environmental impact of the heat wave and thermal release waivers are
debated several lessons have been learned from the experience. For instance, EDF's
"Climate Uncertainty Plan" includes a gradual modification of schedules for refueling
and maintenance outages to keep coastal plants on line in summer (MacLachlan, 2005a).
In earlier years, four or five of the 14 coastal PWRs were off line for scheduled
maintenance simultaneously in summer, the new goal is to have no more than two
reactors off-line at a time. Coastal reactors do not have the same thermal constraints,
since coastal waters remain cool even during heat waves. Other lessons include: the
importance of enhancing commercial deals with big consumers for reducing loads, early
communication to the public, and crisis training for staff (Parey & Aelbrecht, 2005).
In 2005, in compliance with requests for changes to the general operating rules, EDF
reassessed the maximum temperature limits allowable in premises containing equipment
important for safety. The renewal of the discharge and water intake license for the
Nogent-sur-Seine nuclear power plant at the end of 2005 was an opportunity to include
the possibility of higher temperature discharges in certain climatic and power demand
conditions, as with the Bugey, Golfech and Tricastin nuclear power plants (Autorité de
sûreté nucléaire, 2005).
During episodes of heat wave and drought, it became clear that some of the
physical limits used in the design of nuclear power plants or stipulated in their general
operating rules had been reached. Therefore, in 2006 ASN undertook a review of the
heat wave reference documentation to assess the operation of installations in conditions
harsher than those included in the design for the CPY series sites. ASN is expected to
give a decision on the entire documentation in 2008. These reference documentation
systems are still being drafted by EDF for the other plant series (Autorité de sûreté

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nucléaire, 2007). French safety authorities require EDF to study the impact of extreme
temperatures and drought on nuclear plants as part of the periodic safety reviews the
utility must prepare for each of its reactors every 10 years. Since 2003, requirements have
been strengthened and DGSNR asked for an in-depth assessment of facility design to see
if further measures should be taken to make the plants more resistant to extreme climate
conditions (MacLachlan et al., 2006).
During the 2006 heat wave, ASN asked EDF for an analysis of the impact of a
theoretical continued rise in the temperature of the Loire river on the safety of the
Belleville, Chinon, Dampierre and Saint-Laurent reactors. One of the consequences of
these studies led EDF to increase the capacity of certain heat exchangers. This was
completed at the end of June 2007 (Autorité de sûreté nucléaire, 2007). Other potential
fixes include operating measures, and plant modifications that might be implemented in
the 2010-2020 timeframe. The flow rate of the Vienne River is low; therefore, the
Civaux site continues to operate with the use of a special cooling tower that cools down
drainage from the main cooling towers before it is released into the river. This measure
may be implemented at other sites. In order to improve its ability to deal with such
problems, ASN organised a number of meetings with EDF and the General Directorate
for Energy and Raw Materials at the Ministry for Ecology, Sustainable Development and
Spatial Planning (MEDAD), before the summer of 2007. Furthermore, in a memo
addressed to the MEDAD, ASN defined its role in the event of a heat wave and also set
up a heat wave situation decision-making process (Autorité de sûreté nucléaire, 2007). In
addition, DGSNR is looking for suggestions on a 30 year climate plan for France nuclear
plants. However, EDF was unable to find any other utility in the world that has thought
about the influence of climatic conditions on their facilities over the next 30 years
(MacLachlan, 2005a).

7.3. Drought and Heat Waves in the United States
The effects of heat waves and droughts on reactors in the United States have been
less remarkable in part because the U.S. is not as dependent on nuclear for meeting
energy needs. Moreover, heat waves of the spatial extent, duration, and intensity that
have hit Europe have not yet manifested in North America. Typically, regional droughts
and heat waves have posed problems rather than a single climatic event impacting the

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entire country.
Deratings or reduction of power generation due to the temperature of cooling
waters is not uncommon; however, it does not typically pose a significant problem since
thermal limits can often be maintained by reducing power generation by a small amount
at a couple of units in a single region. Nonetheless, the drought and heat wave in 1988
caused significant problems for U.S. nuclear power plants, necessitating deratings,
technical specifications waivers, and a pursuit for alternative cooling water sources at
plants in the Midwest, Northeast and the Southeast (Baker, 1988a). For instance, at the
Waterford-2 nuclear power plant, located along the Mississippi in Louisiana, the operator
considered plans to bring in a few hundred thousand gallons of fresh water per day to
meet the plant's demand for makeup water if the local water supply becomes tainted with
salt water (Baker, 1988a). Salt water contamination had occurred in communities 30
miles to the south of Waterford. Also in Louisiana, the cooling water intake pipes for the
River Bend plant were extended to insure that the intakes stay far enough below the level
of the Mississippi River to operate effectively (Baker, 1988a).
In the Northeast, three nuclear plants were forced to derate due to the heat.
Hudson River water temperatures reached 87˚F in August, forcing Indian Point-2 and
Indian Point-3 to reduce power for short periods. Both Indian Point plants requested and
received temporary waivers for technical specifications relating to maximum intake water
temperature in early August. Indian Point-3's final safety analysis report has also been
recalculated based on the new higher water temperatures. High water temperatures in
Lake Ontario reduced condenser efficiency, causing deratings of up to 20% in July and
August at the Fitzpatrick site (Baker, 1988b).
Half of the nuclear reactor sites in the eight Midwestern states that make up
Region III were affected by heat waves with an average derating of 10% due to a
combination of high service water temperatures, low river levels, and high ambient
temperatures (Baker, 1988b). From July 6th to July 17th of 1988, the two 833-MW BWRs
at Quad Cities in Illinois were limited to an average of 80% power and short-term
deratings have forced the reactors to less than 25% power on some days. At Dresden also
in Illinois, the two 832-MW BWRs have been limited to an average of 84% power over
the same period, with the units being forced as low as 75% power at some times (Baker,
1988a). In August, the situation worsened and Quad Cities and Dresden stayed at or

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below 50% power most of the time (Baker, 1988b).
A combination of low-flow rates and high water temperatures in the Mississippi
River forced the Monticello 580-MW BWR, in Minnesota to go to a partially closed
recirculation mode during July and August. The Mississippi usually has flow rates of
from 2,000 to 4,000 cubic feet per second (cf/s) during the summer months in the area of
Monticello. During the summer of 1988, flow rates were down to 700 to 900 cf/s and
water temperatures averaged 10 to 15 degrees F (5.5 -8.3˚C) above normal. Permits
restrict the percentage of river flow the site can use and during recirculation mode some
condenser water is rerouted back through the condenser a second time to reduce the
amount of river water needed for cooling. Power reductions stemming from this varied,
but at times Monticello was limited to 86% power (Baker, 1988a). Furthermore, new
problems with scaling in the unit's condensers caused by increased silt levels in intake
water developed in August (Baker, 1988b).
A heat wave of the spatial extent and duration that occurred in 1988 has not
occurred since in the United States. Nonetheless, drought and battles over water in
regions with nuclear power plants have been ongoing. In particular, Georgia, Alabama,
and Florida have feuded since 1989 over water with the recent drought worsening the
problem (Manuel, 2008). Alabama and Florida successfully sued Georgia over a state
plan for withdrawing water from Lake Lanier, the main source of drinking water for the
Atlanta metro region. In addition, Lake Lanier feeds the Chattahoochee River, whose
flow is necessary for the survival of endangered species such as freshwater mussels and
sturgeon, and supplies water to towns in Alabama and Florida, and the 1,776-MW Farley
nuclear plant in Alabama (Manuel, 2008).
The US Court of Appeals for the District of Columbia Circuit overruled a lower
court on the question of whether the state of Georgia, the Army Corps of Engineers and
hydropower and water stakeholders in Georgia could reallocate 22% or more of the water
storage at the Lake Lanier reservoir for local consumption. The appellate court concluded
that a reallocation of 22% of the water storage definitely would be a major operational
change requiring congressional approval (Electric Power Daily, 2008a).
This court decision does not signal the end of water battles in this region, or an
end to tough decisions on water allocation. For instance, Georgia senators and
congressional representatives introduced a bill to amend the endangered species act, so

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that it may be suspended during periods of drought. The suspension would take effect if a
drought was a threat to the health, safety, or welfare of the population that is located in
the region. The suspension period would terminate at the end of the drought as
determined by the Secretary of the Army (acting through the Chief of Engineers) or the
Governor of the State ("A bill to amend the Endangered Species Act of 1973 to provide
for the suspension of the act during periods of drought," 2007).
Georgia, Alabama, and Florida are not the only states battling over water in
regions with nuclear power plants. North Carolina and South Carolina are currently
battling in the Supreme Court over water in the Catawba River basin. The question under
review in the Supreme Court is whether, “North Carolina’s interbasin transfer statute is
invalid under the Supremacy Clause of the United States Constitution and the
constitutionally based doctrine of equitable apportionment because North Carolina,
pursuant to that statute, has authorized and continues to authorize transfers of water from
the Catawba River in excess of its equitable share of the waters of that interstate river,
thereby harming South Carolina and its citizens” (State of South Carolina vs. State of
North Carolina, 2007). In 1991, North Carolina enacted an “interbasin transfer statute”
that claims to authorize the transfer of large volumes of water from one river basin in
North Carolina to another basin in that State. Under that statute, North Carolina has
authorized the transfer of at least 48 million gallons per day from the Catawba River
Basin, with the most recent such transfer authorized in January 2007. South Carolina
contends that past transfers and pending transfers exceed North Carolina’s equitable
share of the Catawba River. The Catawba River is an interstate river that originates in
the mountains of North Carolina and flows through a series of lakes including Lake
Wylie, where it enters South Carolina. The Catawba River is essential to the generation
of hydroelectric power, provides cooling water to Duke Energy’s Catawba Nuclear
Power Plant and McGuire Station, and is vital for economic development, commerce, and
recreation. Yet the Catawba River is subject to severe periodic fluctuations in water level
that can render its volume inadequate. North Carolina and South Carolina have issued
drought advisory warnings for the Catawba River Basin and both states agree that
moderate drought conditions currently exist. The most recent prior drought lasted from
1998 through 2002 (State of South Carolina vs. State of North Carolina, 2007).
In the Catawba Basin, McGuire Station has been impacted by the latest drought.

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From July to September 2007 the average rainfall in the system was 4.55 inches
compared to 12.02 inches for a long-term average. Full pond elevation at Lake Norman
is 760 feet above mean sea level (Duke Energy, 2007b). Critical elevation for Lake
Norman was determined to be 750 feet MSL due to thermal limitations associated with
McGuire Nuclear Station. McGuire needed a system modification to operate to 745 ft
MSL which was scheduled during a 2008 outage. At the time of the identification of
critical elevations the modification and schedule were thought to not be a problem
because probability of having a drought worse than 1988-2002 drought seemed low
(Duke Energy, 2007c).
The water of Lake Norman is used in two ways to provide electricity. Lake
Norman is a cooling water source for not only McGuire Nuclear Station, but also for
Marshall Steam Station and powers the generators at Cowans Ford Hydroelectric Station.
In addition, the lake provides a dependable supply of water to Lincoln County,
Mooresville and Charlotte-Mecklenbury and provides 40 percent of the total usable water
storage in the eleven-lake system; furthermore, Lake Norman (along with Lake James)
serves as a vital "shock absorber" to the lake system to lessen the impacts of drought and
high water events on the other reservoirs (Duke Energy, 2007b).
Adding new piping and valves to a back-up system at McGuire Nuclear Station will
allow the plant to operate at lower lake levels. Cost of this work is considered part of
normal operating costs and minor since the power plants in the basin generate about 9000
megawatts of electricity (Duke Energy, 2007a). Modifications on McGuire Nuclear
Station intakes have been completed allowing the minimum Lake Norman elevation
needed to operate McGuire to return to the License Application's Critical Elevation. The
work added approximately 3 feet of available storage in Lake Norman, which represents
approximately 11 percent of the Total Usable Storage of the Project (Duke Energy,
2008).
The North Anna reactor in Virginia was also impacted by the 2002 drought and
as a result modifications were made at this site. On August 9, 2002 the North Anna
Power Station declared a Notification of Unusual Event (NOUE) due to Lake Anna level
decreasing to less than 246 feet above mean sea level (Landis, 2002). The lake level is
related to providing adequate water for normal operating and long term cooling of safety
related equipment. Long term cooling (at least 30 days) is provided by the Service Water

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Reservoir at the site with Lake Anna providing long term makeup to the Service Water
Reservoir via the Screen Wash pumps. The licensee determined that approximately six
additional months of continued drought would be required before it became necessary to
shutdown both units at Lake Anna level of 244 feet. Operating Technical Specifications
for the reactors at the site allow continued plant operation as long as Lake Anna level
remains above 244 feet (Landis, 2002; Twachtman, 2002b).
Company engineers looked into positioning a couple of service water pumps
lower into the man-made lake. Putting the pumps in deeper water would ensure
availability of cooling water even if the lake levels continue to fall. The company also
examined putting in a dam-like structure on the discharge canal to ensure the proper
water level differential exists between the discharged warm water and the cooler water
that the plant takes in. The change is needed to maintain a strong flow of water through
the condenser (Twachtman, 2002a). The modifications would allow the two North Anna
units to operate even if the lake drops several feet below the 244-foot mark. The changes
did not need NRC approval, but did require updating North Anna's final safety analysis
report (Twachtman, 2002a). A total of 15 inches of rainfall in October and November
allowed Dominion to terminate the unusual event on November 18th (Twachtman,
2002c). The lake fell as low as 245.1 feet during the drought and had to rise to at least
246.5 feet before Dominion could exit the unusual event. The lake's water level at full
pond is 250 feet (Twachtman, 2002c).
A third unit is currently planned for the North Anna site. The issue of cooling a
future unit 3 was raised by citizens and officials with the Virginia Department of
Environmental Quality (DEQ) and other agencies, which were concerned about the
environmental impacts on the lake (Weil, 2006). Dominion submitted a supplement to its
early site permit (ESP) application to NRC that contained plans for cooling a potential
third unit at North Anna through a combination of dry and wet cooling towers (Weil,
2006). The earlier application said that a new third unit would use once-through cooling.
A potential unit 4 would use a dry cooling tower system. Revising the cooling approach
for a unit 3 would cost the company more than $200-million, but the cooling tower
system would remove the heat impacts and substantially reduce the additional water
consumption of Lake Anna (Weil, 2006). The third unit would use two operating modes,
either "energy conservation" or "maximum water conservation" (MWC), depending on

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the lake water levels. Two-thirds of the cooling is still done through wet cooling in MWC
mode. When the lake levels were at or above 250 feet mean sea level (MSL), the energy
conservation mode would be used, and this would be the situation most of the time. The
water conservation mode consumes about 11 MW more energy than the energy
conservation mode. The water would flow through the dry tower system before moving
through the wet tower system; however, fans usually would not be turned on in the dry
system. The fans would operate when lake levels remained below 250 feet MSL for
seven days (Weil, 2006).
Drought concerns and the need for adaptive measures have also impacted
reactors in the Midwest. In 2005, the governor of Montana and the Army Corps of
Engineers warned that the Missouri River faced low levels during the summer months
due to drought, which could impact three nuclear plants and 22 coal-fired plants that use
water from the river for cooling. The reduced snow pack was of particular concern, since
Montana received less snow that winter compared to any of the last seven years of
drought. Moreover, dry soil conditions due to persistent drought absorb much of the
runoff before it reaches the Army Corps' reservoirs. The primary concern was that with
reduced flows it would be difficult to maintain energy production without violating
thermal permits (Electric Power Daily, 2005). Thermal issues forced a summer
production cut at the 801-megawatt (MW) Cooper Nuclear Station near Omaha. The
plant's operator, Nebraska Public Power District, bought as much as 25 MW of
replacement power; a significant amount since this region is accustomed to being a net
power exporter (Wagman, 2005). Channel degradation from the self-scouring action of
the Missouri River worsens the drought situation by increasing the exposure of intake
pipes. For instance at Kansas City, the river bed is 11-12 feet deeper than 30 years ago,
helping to drop water levels below intake structures (Wagman, 2005). Along the Missouri
River, utilities are investing millions of dollars for items such as trash rakes and traveling
screens to keep water intakes clean, pumping systems to draw river water into existing
intake systems, and wellfields to pump water out of the ground and into power plant
cooling systems, and cooling towers (Wagman, 2005). Many of these measures have not
only construction costs, but also substantial operational costs particularly in the case of
cooling towers.
While nuclear power plants in the south already have cooling towers in place to

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handle heat waves and droughts, the increased frequency at which the plants must use
cooling towers does have consequences and sometimes even these actions are not enough
to keep plants on-line. Throughout the summer of 2007, Browns Ferry and Sequoyah
nuclear plants frequently used cooling towers requiring a substantial amount of power
that the utility would have otherwise sold (Electric Power Daily, 2008b; TVA Regional
Resource Stewardship Council Meeting Minutes, 2007). Running cooling towers reduces
the power output by less than two percent of the average net power output of the facility
during normal conditions, but during heat waves the reduced output increases to 4 percent
of the facility’s net output (U.S. Department of Energy, 2008). For the Tennessee Valley
Authority (TVA) this small percentage can be significant because the TVA generates 30
percent of its power at nuclear plants and sells electricity to 8.7 million people in seven
states (Weiss, 2008). In addition, the drought and heat wave forced the TVA to regularly
and systematically cut power production (Power Markets Week, 2007). The mountain
reservoirs, which typically keep the water temperature downstream within normal limits
were at a historic low of an average 19 feet below normal (Power Markets Week, 2007).
Furthermore, the drought conditions in the area were more severe in 2007 than any time
previous in Browns Ferry’s operational experience (U.S. Nuclear Regulatory
Commission, 2008a).
Meanwhile the heat wave was causing record demands for energy. The peak
demand was a record 33,499 MW on August 16th, while the previous record of 33,334
MW was reached on August 8th. Demand was near but slightly below the record after
industrial customers and distributors were asked to reduce usage (Power Markets Week,
2007). The TVA tried to control the temperature of the river by cutting back power at all
three units at the Browns Ferry site, but ultimately was forced to shut down Unit 2. The
plant's other two units were scaled back to 74% production on August 16 and August 23
(Power Markets Week, 2007).
At the Browns Ferry Nuclear Plant and the Cumberland Fossil Plant 24-hour
sampling was required during the heat wave. Browns Ferry was shutdown because the
Tennessee River exceeded 90˚F average over 24 hours (TVA Regional Resource
Stewardship Council Meeting Minutes, 2007). However, the potential for tough decisions
in the future became evident. According to the TVA, the first priority during a drought is
to first guard health and safety of the public and not let intakes become exposed and next

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to protect water quality and downstream habitat (TVA Regional Resource Stewardship
Council Meeting Minutes, 2007).
The U.S. NRC determined that the drought conditions that existed in the
Tennessee Valley during 2007 were a likely contributor to a large fish kill and resulting
event at Brown’s Ferry in January 2008. A large number of Threadfin shad were drawn
into the intake structure at Browns Ferry and caused clogging and damage of the
traveling water screens. This reduced the Condenser Circulating Water (CCW) flow and
resulted in an unplanned power reduction (U.S. Nuclear Regulatory Commission, 2008a).
Threadfin shad may experience shock when there is a water temperature change of
greater than 2˚F in a 24-hour period or when water temperature falls below 45.5°F. The
fish stun began during the morning hours of January 2nd, 2008 when river temperature
fell to 45.5°F. Shortly thereafter, the temperature reached the greater than 2°F change in
24 hours. While the exact cause for the thermal shock cannot be determined, TVA River
Operations had significantly varied river water flows for several days prior to the event to
support meeting peak power demands. A rapid increase in river flow could result in a
temperature drop sufficient to result in thermal shock; however, the thermal shock could
have occurred naturally. Unusually cold weather can cause the water temperature to fall
to 45.5°F or to be cooled 2°F in 24 hours and such conditions did exist prior to the event
(U.S. Nuclear Regulatory Commission, 2008a). Nonetheless, the drought established
conditions where an increase in river flow could result in a more extreme change in
temperature. Moreover, this event demonstrates that planning and operating nuclear
power plants during drought is a complicated task with many factors to consider.

7.4. Biological Fouling in Canada and the United States
Many forms of aquatic life or debris can cause problems with the cooling water
intake system at nuclear power plants. Cladophora algae are of particular concern since
problems with algae have arisen multiple times at the same reactors particularly in the
Great Lakes. While Cladophora is a problem throughout the Great Lakes, the thermal
discharges of nuclear power plants create a local environment that is thermally enriched
compared to other areas, thus potentially enhancing algae growth locally (Ontario Power
Generation, 2007). An algae bloom in itself is not enough to cause a problem with the
intake system. A strong wind that breaks the attached algae away from rocky substrates is

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also necessary. Ontario Power Generation (OPG) recognizes that climate change could
worsen this problem. Increase in water temperature in Lake Ontario would lead not only
to warmer intake water temperature, but also increased algal and zebra mussel growth
and alteration of fish communities. In addition, extreme weather events would result in
greater disturbance of algae leading to greater quantities of algae becoming detached
(Ontario Power Generation, 2007).
The severe weather resulting from hurricane Isabel on September 19, 2003
caused algae to accumulate in the Pickering B screenhouse. Unit 7 was proactively shut
down to reduce the cooling water load and avoid tripping multiple units, but was able to
return to power within two days (CNSC, 2004). A more problematic event occurred in
2005. On August 19, Pickering B shut down three of the four operating units due to wind
conditions that resulted in a large influx of algae to the screen house. Fouling of the
screens temporarily reduced the intake flow of cooling water for the turbine condensers,
causing the turbines to trip. A review of the event determined that the three units were
shut down before a standby generator and a high-pressure emergency core coolant pump
were started (CNSC, 2006). As a result, for approximately two hours, no power would
have been available to the high-pressure emergency core coolant pumps that were
necessary to ensure fuel cooling in the event of a loss of coolant accident and loss of offsite power to the remaining operating reactor (Unit 7). A simultaneous loss of coolant
accident and loss of off-site power is deemed to be unlikely; however, following the
shutdown of three units, the probability of a loss of off-site power was higher than normal
(CNSC, 2006). Also in 2005, OPG's Darlington Generating Station reduced its electrical
output as a result of algae and silt blockage in its water intake system. High winds and
stormy lake conditions caused an abnormally large amount of algae and silt to enter the
station's water intake systems. To protect equipment, Darlington personnel safely shut
down Unit 1 which was affected by blockage (OPG, 2005). In 2007, an incident
involving algae clogging of the intake cooling water system at the Pickering station
necessitated unit de-ratings, one unit forced outage, and a delayed unit restart. OPG has
tried to take corrective actions by installing a diversion net by the water intake and
improving upon mitigating operating procedures, but these changes have not been
completely effective (CNSC, 2008).
OPG estimates that Cladophora fouling of cooling water intakes at the Pickering

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and Darlington nuclear power plants along Lake Ontario has cost the company more than
$30 million in lost power generation in the last 12 years (Hamilton, 2007). Therefore,
potential solutions are being explored by OPG. Current operations dictate that pumps are
shut down and reactor power levels are reduced if there is a perceived threat of algae
intrusion. In the event that intake water flow is considerably restricted by aquatic plants,
and the mechanical rakes and traveling screens cannot re-establish or maintain sufficient
flow, reactor power would be reduced due to reduced cooling water availability (Ontario
Power Generation, 2007). A long-term option would be to draw deeper, cooler water
rather than water from the littoral zone where the highest densities of Cladophora occur.
This long-term option offers additional advantages including reduced silt, less fish
impingement and a reduction in the temperature of intake water. OPG and the Regions of
York and Durham have commissioned a study at the University of Waterloo to assess the
sources of the algae affecting the lake in the vicinity of the Pickering site. The study will
propose preventative or ameliorative measures (Ontario Power Generation, 2007).
On several occasions, the FitzPatrick nuclear power plant, located on the U.S.
side of Lake Ontario, has encountered problems with algae intrusion at the circulating
water intake structure causing blockage of the Traveling Water Screen (TWS) (U.S.
Nuclear Regulatory Commission, 2008a). Traveling screen blockage has the potential to
lead to a cascade of events. Failure of a single screen can lead to multiple screen failures
which can cause a loss of the Circulating Water System, loss of inlet cooling water for
the plant, and eventually can cause loss of the main condenser (U.S. Nuclear Regulatory
Commission, 2008a). Because of these events, Fitzpatrick has responded by reducing
power in order to take a circulating water pump(s) off line to reduce water velocity and
thus algae adherence to the TWS (U.S. Nuclear Regulatory Commission, 2008a).
Algae intrusion events requiring shut down or down power occurred at
FitzPatrick nuclear power plant on September 12th, October 13th, October 28th, and
November 16th, 2007. During the September 12th event, the algae caused an overload
condition to the traveling screen system beyond their design capacity. The downstream
TWS buckets were pushed into the concrete by increased water velocity. The water
velocity was increased by a lower lake level combined with upstream screen debris
loading induced flow restriction. This concrete impact increased the rotation resistance
which contributed to shear pin failure and/or fluid coupling slippage (Deretz, 2007).

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Operators responded appropriately by reducing reactor power, inserting a manual scram
and placed the plant in a stable condition. In order to restore the traveling screen system
to service it was necessary to cooldown and depressurize the plant. During the cooldown,
the feed water startup flow control valve operated sluggishly. Operators were challenged
by control room feedwater flow instrumentation that does not provide adequate range or
resolution for monitoring the control valve response at low flow rates (Deretz, 2007).
Reactor level lowered to the scram initiation setpoint, but was subsequently restored and
the cooldown completed satisfactorily (Deretz, 2007).
Changes in operating procedure and strategy were in place after the September
event; however, these actions were inadequate on October 13 when high winds led to
clogging of the Traveling Water Screens. Once clogged the TWS motors were unable to
maintain continuous operation. The increasing differential pressure resulted in the TWS
shear pins shearing off to protect the TWS motors. Once the TWS became stationary the
continuing suction from the plant circulating water pumps resulted in further plugging of
the TWS such that the only means available to maintain the Ultimate Heat Sink level was
to reduce power and secure circulating pumps (Deretz, 2007).
Once the TWS were clogged and stopped the only means to lower the differential
pressure across the TWS and allow movement of the TWS was to take the plant to cold
shutdown and secure all CW pumps. By securing the suction from the back side of the
screen the TWS motors were able to lift the TWS out of the water to be cleaned. These
events made apparent the need for both equipment upgrades and procedural changes
(U.S. Nuclear Regulatory Commission, 2008a). Equipment upgrades include: higher
strength shear pins, downstream screen guide rails, larger motor on screen drive train
enabling higher speed operation, screen wash diversion troughs, and fire hoses available
for cleaning. Procedure Changes and Detection/Mitigation strategies include: a lowered
setpoint for screen differential pressure alarm, added guidance for use of fire system
sprays on screens, installed web cam at fish basket, training of operators on shear pin
installation, and additional guidance for power reduction based on weather forecast.
Trigger points are used to change operational procedures. For instance if severe weather
causes sustained winds greater than 20 mph (32 km/hr), or if other conditions that could
cause a rise in the amount of debris in intake water exist or are expected, then the
following actions will be performed: the traveling screens will be put into continuous

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mode, and the traveling screen performance and debris basket quantity will be frequently
monitored. If significant lake debris is incoming, then screen performance, debris basket
quantity and screen differential level will be continuously monitored. If there is
indication of a rising screen differential pressure then the fire houses are used to clean the
screens. In addition, FitzPatrick has also taken steps to minimize Cladophora by using
divers to harvest the algae in areas of high concentration (U.S. Nuclear Regulatory
Commission, 2008a).
The U.S. NRC did not consider the algae problems at FitzPatrick a performance
indicator because the situation was not foreseeable. Until the Traveling Water Screen
improvements are complete, additional power reductions due to algae intrusions of this
magnitude will not to be counted by the U.S. NRC as a performance indicator as long as
proactive procedures to lessen the severity of the event have been implemented by the
licensee. After the Traveling Water Screen improvements are complete, algae intrusions
of this severity will be counted as a performance indicator (U.S. Nuclear Regulatory
Commission, 2008a).
According to an NRC special inspection report, Kewaunee along Lake Michigan
has also experienced problems with Cladophora fouling. Inspection of the 'A' safety
injection pump lube oil cooler during a scheduled quarterly inspection on January 15th,
2004 revealed silt and Cladophora accumulation at the tube pass inlets (S. A. Reynolds,
2004). The licensee identified that 17 of 20 tubes in each pass were blocked. The flow
was measured between 3 and 3.8 gallons per minute (gpm), while after cleaning flow was
measured between 5.95 and 6.05 gpm. This finding prompted an investigation into the
condition of the 'B' safety injection pump lube oil cooler. Seventeen of 20 tubes in each
pass of this cooler were also blocked and tests revealed that there was no flow in the 17
tubes. Plant operators declared both trains of the high pressure safety injection system
inoperable at 12:20 am on January 16th and a plant shutdown was commenced 1 hour
later in accordance with Technical Specifications (S. A. Reynolds, 2004).
Significant fouling of the safety injection pump lube oil coolers with Cladophora
was identified as early as 1992 when the coolers were first opened and inspected. On
October 2001 both coolers were inspected. Eighty percent of the tubes on both passes
were found blocked with Cladophora and silt on the 'B' safety injection pump lube oil
cooler. All of the tubes on both passes were found blocked on the 'A' safety injection

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pump lube oil cooler. The condition evaluation discussed five possible corrective
actions; however, no corrective action was implemented. In May 2002 the licensee wrote
an engineering work request to evaluate a modification to replace the existing coolers
with a different design having larger diameter tubes to minimize fouling (S. A. Reynolds,
2004).
The inspectors noted that the assessment did not mention any consideration of the
actual amount of tube plugging which would also affect the heat removal capability of the
coolers. In May 2003, the licensee completed a review of abnormal plant conditions or
indications that could not be easily explained. The licensee identified that the fouling of
the safety injection pump lube oil coolers was widely known issue which had not been
pursued, had existed for a long period of time, and had the potential to affect an important
piece of safety-related equipment. It did not appear that the licensee had identified the
fouling as a significant condition adverse to quality and did not routinely document the
results in the corrective action program for evaluation, trending and early identification of
problems. There were no condition reports specifically associated with the results of
recent safety injection pump lube oil cooler inspections in May 2003 and October 2003.
The inspectors were concerned that the licensee had missed many opportunities to correct
the problem sooner because the licensee had not correctly evaluated the longstanding
degraded condition (S. A. Reynolds, 2004).
Currently attentive monitoring is the best strategy to deal with biological fouling;
however, even with monitoring shutdown and power reductions are necessary to maintain
safe operations. Similarly, maintaining adequate flood protection requires vigilant
attention to changing conditions, in particular, whether design basis flood levels
determined during plant construction remain adequate today. Upgrades to flood
protection and intake adjustments incur considerable costs. These financial investments
are small compared to the costs associated with alternative cooling systems that are
needed to deal with drought and heat waves. In addition, nuclear power plant operation
impairs the ability of natural and human systems to adapt as indicated by the thermal
release waivers issued in France during heat waves, and the water battles in the
southeastern United States.

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8. Discussion
According to considerable scientific evidence, we are now experiencing the
impacts of anthropogenic climate change. While societies have a long record of
managing the impacts of climate events, additional adaptation measures will be needed to
reduce the adverse impacts of projected climate change and variability, regardless of the
level of mitigation achieved over the next few decades (IPCC, 2007b). Nuclear power
has the potential to mitigate for climate change because it does not produce greenhouse
gas emissions during the generation of electricity. However, mitigation measures must
also adapt to climate change and the mitigation measure might in turn impair the
adaptation of systems to climate change. Adaptation and mitigation have both tradeoffs
and synergies, but little research has been done to explore the problems and the
opportunities between the two measures. The criteria developed here to evaluate the
Adaptation-Mitigation Dilemma are applied to nuclear power, but could be used to
evaluate any mitigation measure.
The first part of this chapter reviews the criteria and compares nuclear power
operation at both inland and coastal sites. The summation of this work answers the
question: Is nuclear power a practical solution to climate change? The second part of the
chapter addresses the adaptation-mitigation dilemma by looking specifically at adaptation
problems pertaining to energy supply and by suggesting strategies in using the criteria to
evaluate other mitigation projects.

8.1. Evaluation of Nuclear Power
8.1.1. Interrupted Operation
Extreme climate events interrupt operation at both inland and coastal sites.
However, the consequences of interrupted operation at inland sites are more severe
compared to coastal locations. While reactors often need to shut-down during coastal
storms, typically the reactors are able to resume power generation soon after storms have
passed. Storms cause considerable damage to the transmission system, and these
damages delay restart of nuclear power plants after storms more than damage sustained at

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the nuclear power plant itself. In addition, during severe storms evacuations occur and
therefore demand for energy is low.
In contrast, heat waves threaten continued operation at a time of peak demand. A
combination of low-flows due to drought and warmer temperatures in summer months
raises the temperature of cooling waters prior to the onset of heat waves. Due to physical
constraints related to the Carnot efficiency nuclear reactors produce less energy with an
increase in the temperature of cooling water. When heat waves hit, and nuclear power
plants must reduce power to comply with thermal release regulations, the supply shortage
becomes even greater. Consequently, power needs to be supplemented from other
sources that potentially emit greenhouse gases.

8.1.2. Financial Costs
The measures needed to adapt to climate change require considerable financial
cost whether at inland or coastal sites. The cost for certain adaptation measures are
deemed minor for existing nuclear power plants because of the economic importance of
maintaining the supply of energy and the high costs associated with building a new power
plant. For instance, flood protection and intake adjustments are absolutely necessary for
continued operation and expenses for these modifications are generally cost efficient. In
contrast, the expense of upgrading cooling systems to use less water can be cost
prohibitive and deemed unpractical for aging nuclear power plants. While flood
protection has high construction costs, alternative cooling systems have both high
construction and operating costs.
Cost overruns continue to afflict nuclear power plant construction, and additional
costs necessary to adapt to climate change could make some sites economically
unfeasible. For dry cooling to become more widely accepted in the future, there needs to
be better data on the performance penalty of these systems under a range of climatic
conditions and also on the additional capital and operational costs associated with
implementing these systems (Micheletti & Burns, 2002). The high costs, and uncertainty
of exact costs, prevent the adoption of dry cooling systems unless there is pressure from
stakeholders outside the utility companies. For instance, at the North Anna site the issue
of cooling a future third unit was raised by citizens and officials from state agencies;
subsequently, the utility changed their plans from once-through cooling to a hybrid

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system that uses both dry and wet cooling at an additional cost of $200 million (Weil,
2006).
Climate change means that the past can no longer be used to predict the future;
however, uncertainty in predicting climate continues to cause problems in planning. For
example, at the McGuire nuclear power plant in the United States, critical elevations for
the reservoir were identified and the modifications and schedules were thought not to be a
problem: the probability of having a drought worse than the drought from 1988-2002
seemed low. The adjustments were planned for a 2008 outage but had to be moved to an
earlier date, because what was previously considered improbable had occurred. The
inability to predict climate impacts can increase costs substantially when adjustments
necessitate unscheduled shutdowns.

8.1.3. Adaptation Impairment – Human Systems
The financial resources needed to protect nuclear power plants from coastal
impacts could in itself impair the adaptation of human systems. Nuclear power plants
can not be abandoned; therefore, coastal locations will need to spend money on
improving coastal defenses. The money spent protecting nuclear facilities means less
money is available to finance the protection of other coastal developments. In addition,
the protection of one piece of shoreline can increase erosion further along the shore. For
example, losses of beach area have been noted near the San Onofre nuclear power plant.
Damages to the coast and impairment of human systems are not immediately apparent,
but models demonstrate future impacts to the coast. These models serve as an important
tool in planning for future developments.
While adaptation at coastal locations involves planning for the future, recent
events demonstrate that operations of nuclear power plants at inland locations have
already impaired the ability of human systems to adapt. States with nuclear power plants,
specifically in the southeastern U.S., are waging legal battles for water indicating the
challenges for these regions to adapt to drought. Another area of serious concern is the
vulnerability of nuclear power to heat waves. In terms of lives lost, heat waves are the
most dangerous of extreme climate events; therefore, reliability of the energy grid is
essential to assure public safety. Thus far blackouts during heat waves have been
avoided, but this has often come at the expense of natural systems.

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8.1.4. Adaptation Impairment – Natural Systems
Coastal habitats must adapt to a rise in sea level; however, development along the
coast leads to a loss of coastal habitats as the land types are not able to “move” inland to
accommodate to rising seas. Restricting development along the coast remains the best
strategy to reduce loss of coastal habitat. Sites for nuclear power plants must be suitable
for 100 years; therefore, planned retreat is no longer an option at these locations.
Moreover, preventing erosion by building hard defenses reduces the sediment supply
needed to build valuable habitats (Cronin et al., 2003). While loss of coastal habitat
occurs slowly, over time the cumulative losses become substantial.
Similarly, the impacts of thermal pollution during heat waves might not cause
large fish-kills and thus are not immediately apparent. However, the combination of
higher temperatures from climate change and the warm effluent from nuclear power can
cause serious changes to ecosystems. In France easing of environmental regulations has
become a permanent feature due to the issuance of a permanent order in 2004 allowing
higher thermal releases during summer months. The mollusc communities in France’s
rivers have shown low resistance to changes in water temperature and extinction of
several species is likely to occur due to high water temperatures (Mouthon & Daufresne,
2006).
Likewise, during a drought water needs must be prioritized. For example, the
Tennessee Valley Authority places priority in not letting intakes becoming exposed
during a drought, while maintaining water quality and quantity for aquatic ecosystems is
secondary. Unless real solutions to climate change are deployed, indications are that
these choices will need to be made more often as the frequency and duration of droughts
and heat waves increase. For instance, in the United States a bill has been introduced in
the house and the senate by Georgian senators and congressional representatives to waive
the Endangered Species Act during times of drought.

8.1.5. Other Environmental Problems
Nuclear power has the potential for catastrophic accidents and consequently
widespread environmental damage, unlike any other form of energy. Therefore the
possible costs of not adapting nuclear operations to climate change are exceptionally

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high. Safe operation during extreme climate events remains a challenge. Yet, the
response to climate change by many utility companies and nuclear regulators has been
slow. France has taken the lead in addressing climate change because of problems
encountered with floods and heat waves. Electricité de France is working on a 30 year
plan that addresses how climate will impact power generation, but they have been unable
to find any other utility in the world developing similar plans. As well, the nuclear safety
authority in France is working with the IAEA on developing guidance on floods and
climate change that will be ready next year.
The uncertainty in predicting climate change poses a problem for safety.
Historical flood levels are no longer an adequate predictor of future floods. As seen in
France, recent floods have exceeded design basis levels. The 1999 Le Blayais flood led
to the examination of design basis flood levels for other nuclear power plants in France
and the implementation of additional flood protection measures. In contrast, despite the
threat of a change in hurricane intensity and sea level rise, the U.S. NRC is using a
method that derives lower surge levels than previously used methods. While the old
method was determined to be obsolete, additional margins should be included in design
basis estimates to account for climate change. NOAA’s refusal to release the model that
contradicted other studies and demonstrated appreciably greater surge heights makes
analysis of this situation much more difficult. Interviewing those involved in developing
surge models could arrive at a more definitive answer on the accuracy of each of the
models and constitutes an area of future work.
Regardless of design parameters, storms at coastal locations continue to be a
problem because they often lead to the failure of multiple systems, and despite previous
experience failures in alarm and communication systems continue to occur. In addition,
experiences are often not shared between sites. Nuclear power plant operators at
different locations encountered similar problems that could have provided learning
opportunities, but these opportunities have been missed. For instance, multiple sites in
the Great Lakes region in both the United States and Canada have encountered problems
with biological fouling due to Cladophora; yet, a coordinated effort to deal with the
problem has not occurred.
In certain cases, licensees have shown a low awareness of potential problems
caused by external events; as a result, the response to problems has not been adequate.

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Biological fouling of the safety injection pump lube oil coolers was identified as a
problem requiring monitoring after significant fouling occurred in 1992 at Kewaunee
along Lake Michigan; yet, inadequate monitoring lead to an accumulation of silt and
Cladophora necessitating shutdown of the reactor in 2004. Moisture buildup leads to
equipment failure; nonetheless, a licensee at one site did not recognize the problem as
something requiring preventative and corrective measures. In addition, after a hurricane
had passed a site in Florida, the missile shield doors that protected safety related
equipment were found open. The licensee stated that the doors could have been open for
several years. These examples indicate that licensee’s do not always take proper action
in dealing with external events; moreover, they are not prepared for the issues that will
arise due to climate change.

8.1.6. Is Nuclear Power A Practical Solution To Climate
Change?
Questions abound around nuclear power about impaired operations, potential
high costs of adaptation, impairment to other forms of adaptation, and other
environmental problems. Nevertheless full evaluation of climate impacts remains
difficult. Security issues related to nuclear power operation pose the most important
barriers. In addition, utility companies are secretive about power purchase agreements
that arise when nuclear power plants are not operating. Providing the details on the costs
and the sources of power is viewed as hindering the companies’ competitiveness.
Moreover, those utilities that had to make adjustments to intake structures do not report
the costs of adjustments. Regardless, climate impacts to nuclear power clearly hinder
safe operation and cause financial repercussions.
According to estimates, nuclear power capacity must be tripled to make a
significant reduction in greenhouse gas emissions. Taking into consideration the
replacement of aging reactors this means approximately 1000 reactors will need to be
constructed worldwide (MIT, 2003; Socolow et al., 2004). Siting nuclear power plants
requires consideration of regional climate impacts. Constructing nuclear power plants at
existing sites is the quickest option, but existing nuclear power plants are already
vulnerable to climate impacts. Many regions of the world are already experiencing water

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shortages which will only become worse with climate change. For instance, the Hadley
Centre Global Climate Model predicts that the proportion of the land surface in extreme
drought will increase from 1% for the present day to 30% by the end of the twenty-first
century (Burke et al., 2006). Seasonal changes in precipitation, such as reduced snow
pack and drier summers, pose problems for operation as well. Appropriate inland sites
for nuclear power plants will be more limited in the future because of diminished water
resources. Restrictions on coastal developments are already in place; therefore, the lack
of suitable sites at inland locations can not be addressed simply by locating nuclear power
plants along the coast.
The high risk and high investment associated with nuclear power necessitates an
all or nothing approach to nuclear power expansion. Addressing concerns regarding
waste, proliferation, and safety requires considerable financial investment. Nuclear power
competes for limited research money that could be used to expand solutions that exploit
the synergies between adaptation and mitigation. The few regions where nuclear power
will work do not justify the financial investment required for new reactor designs. A
practical solution to climate change manages both mitigation and adaptation. While
some tradeoffs between mitigation and adaptation will likely be necessary, one can not be
sacrificed for the other. Nuclear power meets all the criteria identified as problematic
characteristics of purported solutions for climate change, and thus it can not be
considered a practical solution for climate change.

8.2. The Adaptation-Mitigation Dilemma
Nuclear power is not the only mitigation measure that has consequences for
adaptation, and it is not the only form of energy vulnerable to climate change. The IPCC
2007 report stressed that it is essential to look at how the various components of the
energy-supply chain might be affected by climate change. Moreover, a robust predictive
skill is required to ensure that any mitigation programs adopted now will still function
adequately if altered climatic conditions prevail in the future (Sims et al., 2007). A
diverse energy portfolio which considers climate vulnerability is essential to adaptation.
For instance, the heat waves in Europe occurred during a time of drought; therefore,
hydro power production was low. The lack of cooling water affected both nuclear and
coal, and wind power production was low because the air was still. While solar power is

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potentially vulnerable to climate change due to increased cloud cover (Sims et al., 2007),
it is not vulnerable to heat waves.

One important first step towards incorporating solar

power into the energy supply system would be to use it at public institutions that are used
as cooling centers, such as hospitals, or private facilities, such as shopping malls. This
would provide relief during heat waves, without increasing demand from those sources of
energy that are vulnerable to heat waves, and would therefore serve as both an adaptation
and mitigation strategy.
The supply side of the energy equation is not the only area that must be
addressed. Measures that address both adaptation and mitigation should be deployed first,
such as reducing energy demand. For instance, insulating homes would keep homes
cooler during heat waves thus supporting adaptation, while the reduction in energy
consumption serves as a mitigation strategy (Bosello, 2005). In developing countries,
decentralized renewable energy addresses critical climate change adaptation needs,
particularly in rural areas where people have no access to electricity, while also
addressing mitigation objectives (Venema & Cisse, 2004). In developed regions, moving
towards a decentralized energy system would mitigate for climate change by reducing
transmission losses and allowing for the use of more intermittent sources of energy such
as wind and solar (Butler, 2007; Sims et al., 2007). Additionally, a decentralized system
is an adaptation strategy because it reduces the congestion of transmission systems during
times of peak-demand. Furthermore, the transmission infrastructure sustains considerable
damage during storms as indicated by past hurricanes. A simpler transmission system
reduces the number of areas that need repair after storms, thus fulfilling another
adaptation strategy.
Options that address both adaptation and mitigation are not limited to energy
supply. Planting trees mitigates climate change and trees in urban locations provide relief
during heat waves by reducing the heat island effect (Klein et al., 2005). The criteria
developed and used in this thesis are limited in that they only address trade-offs to
adaptation and do not evaluate the synergies between adaptation and mitigation.
However, the criteria could easily be expanded to consider synergies. This would be
particularly helpful in evaluating those mitigation measures that impair adaptation in
some regions, while improving adaptation in other regions. For example, if conservation
tillage practices are pursued to sequester carbon, the rotation length and choice of

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agricultural crop could differ from the rotation length and crop most adaptable to climate
change (Wilbanks et al., 2003). In this case the mitigation project would impair
adaptation. However, conservation tillage can also lead to better soil moisture retention
(Blevins et al., 1971). Therefore in this example, mitigation also acts an adaptation
strategy, particularly in mid-continental areas that are projected to experience summer
drying.
Climate change is not going to be solved by one simple solution that can be
applied everywhere. It is a global problem, but the impacts are felt regionally.
Therefore, addressing climate change must be based on regional needs and impacts. The
criteria set forth here elucidate consequences of mitigation and can be used to decide on a
strategy that is the best fit for a particular region. Ignoring adaptation in the search for
mitigation solutions will produce mistakes with serious consequences.

149

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171

Appendix 1. Fission and Nuclear Power Plants
Fission is possible for only a few isotopes of uranium and plutonium:
239

233

U, 235U,

Pu, and 241Pu. The fissionable nuclide in thermal reactors is 235U. Natural uranium

consists of 0.7% 235U and 99.35% 238U. Uranium enrichment is necessary for reactors that
require a higher fraction of 235U than is found in natural uranium. Several different
methods of enrichment exist including gaseous diffusion, centrifuge separation,
aerodynamics processes, electromagnetic separation, and laser enrichment; however, only
gaseous diffusion and centrifuge operate on a commercial scale (Bodansky, 2004; World
Nuclear Association, 2008e).
The energy of the neutrons inducing fission constitutes one of the major classes
of nuclear reactors. Reactors can be classified as either thermal or fast reactors, although
a large majority of reactors are thermal. A thermal reactor has a moderating material
either light or heavy water, or carbon in the form of graphite or beryllium. A good
moderator has a low atomic number, a large scattering cross section, and a small
absorption cross section. A large scattering cross section indicates that it is able to reduce
the kinetic energy of the neutrons. Neutrons that are absorbed by the moderator would
decrease the number of neutrons available for fission. Therefore, the moderator must
reduce the energy of the neutrons, while not reducing the actual number of neutrons by a
substantial amount. A large portion of the core of the nuclear reactor is composed of the
moderator.
Fission begins when a fissionable nucleus captures a thermal neutron. Capture
upsets the internal force balance between neutrons and protons in the nucleus. The
nucleus splits into two lighter nuclei, and an average of two or three neutrons is emitted.
The emitted neutrons are fast neutrons, some are not slowed, and thus do not result in
fission. If one of the neutrons emitted is captured by another fissionable nucleus a second
fission occurs similar to the first. Nuclear power depends on a self-sustaining chain
reaction: that is each fission reaction must continue to trigger one more fission reaction.
Fast neutrons have many fates. Surrounding the reactor cores is either a reflector
or blanket. The reflector prevents neutrons from leaking out by reflecting the neutrons
back to the core, whereas a blanket captures neutrons leaking from the core. A good
reflector has the same characteristics as a good moderator (Foster & Wright Jr., 1977).

172

The blanket and reflector are surrounded by a shield to minimize radiation that leaves the
area.
While a self-sustaining chain is necessary to produce nuclear power, the reaction
must always remain under control. Control materials are needed to regulate reactor
operation and provide a means for rapid shutdown. Removing neutrons from the reactor
core will decrease the power and reaction rate. Boron and cadmium are good control
materials because of their high cross sections for the absorption of thermal neutrons.
Typically the control material is in the form of control rods with either boron carbide or
cadmium in a silver-indium alloy. Boron may also be introduced into the circulating
cooling water to regulate reactor operation (Bodansky, 2004).
Coolants should have a high specific heat, high conductivity, good stability, good
pumping characteristics, and low neutron absorption cross section (Foster & Wright Jr.,
1977). Liquid metals have a high boiling point and therefore can be used at low
pressures; however, metals must be preheated prior to reactor startup (Foster & Wright
Jr., 1977). Coolant is contained within a pressure vessel because the most efficient
transfer of heat occurs under pressure. Water is typically kept at 340˚C, since steam is
not an effective coolant, and above 375˚C liquid water cannot exist. When gases or
liquid metals are used as reactor coolants the coolant can reach a much higher
temperature because the liquid-gas phase transition is not a concern as it is in water.
Moreover, dry superheated steam at 540˚C allows smaller, less expensive, turbines to be
used permitting higher thermal efficiencies (Shultis & Faw, 2008).

173

Appendix 2. Reactor Types
While a reactor is classified as either fast or thermal, the type of nuclear reactor is
further categorized according to the coolant, moderator, and fuel utilized by the reactor.
The majority of reactors currently in operation and under construction use water as a
coolant and a moderator as shown in Table 1. This may be due to technical and
economic advantages or because of historical and commercial forces (Bodansky, 2004).
Reactors that use light water as the coolant and the moderator include pressurized water
reactors (PWR) and boiling water reactors (BWR). Nevertheless, all current reactors
depend on cooling water. The steam or heated gas that moves the turbine must be cooled
by water in order to be used in another cycle of energy generation.

Table 1. Nuclear power plants in operation and construction according to type. Data
obtained from PRIS database (IAEA, 2008b).
Reactor Type
Pressurized Water
Boiling Water
Pressurized Heavy Water
Gas-Cooled
Light Water Graphite
Fast Breeder

Coolant

Moderator

Fuel

Water
Water
Heavy Water
CO2
Water
Liquid Sodium

Water
Water
Heavy Water
Graphite
Graphite
None

Enriched Uranium
Enriched Uranium
Natural Uranium
Natural/Enriched Uranium
Enriched Uranium
Uranium or Plutonium

Operational
Construction
Units MW(e) Units MW(e)
265 243178
94 85044
44 22362
18
9034
16 11404
2
690

25
2
4
0
1
2

22096
2600
1298
0
925
1220

Pressurized water reactors have two water loops. The primary loop is pumped
through the reactor to remove the thermal energy produced by the core. Water in the
primary loop is held at a high pressure to prevent water from boiling. The water is passed
through a steam generator where the secondary-loop water is heated creating high
pressure steam that turns the turbines. The boiling water reactor has a single loop and the
cooling water boils while passing through the core. The steam passes directly to the
turbine and the low pressure steam leaving the turbine is condensed and pumped back to
the reactor.
The heavy water reactor has two loops with the primary loop containing
pressurized heavy water that is used to cool the core. The fuel is contained in pressure
tubes through which the heavy water coolant passes. Pressure tubes pass through the
moderator vessel, which is also filled with heavy water. The heavy water in the primary
loop then passes through steam generators to boil the secondary-loop light water. A
hybrid design of the heavy water reactor also exists where heavy water is used as the

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moderator only and light water is used as a coolant with only a single loop.
In a gas cooled reactor carbon dioxide or helium gas is used as the core coolant
by pumping it through channels in the solid graphite moderator. The fuel rods are placed
in these cooling channels. The heated gas then passes through steam generators where
water is heated to produce steam which in turn drives the turbines. In high-temperature
gas cooled reactors the fuel is packed in many channels in graphite prisms. Helium
coolant is pumped through channels bored through the graphite prisms and the hot helium
goes to a steam generator.
Fuel is placed in fuel channels in graphite blocks that are stacked to form the core
in light water graphite moderated reactors. Vertical pressure tubes are also placed
through the graphite core and light water coolant is pumped through these tubes and into
an overhead steam drum where the two phases are separated and the steam passes directly
to the turbine.
In a fast reactor, the chain reaction is maintained by fast neutrons. Moderator
material cannot be used in the core, so to avoid materials of low atomic mass; the core
coolant is a liquid metal such as sodium or a mixture of potassium and sodium. Sodium
becomes radioactive when it absorbs neutrons and also reacts chemically with water. To
keep radioactive sodium from interacting with the water/steam loop, an intermediate loop
of non-radioactive sodium is used to transfer the thermal energy from the primary sodium
loop to the water/steam loop. Fast reactors can be used to produce fissile fuel exceeding
that which is consumed during the chain reaction. In these reactors 238U is converted to
fissile 239Pu or 232Th into fissile 233U.

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Appendix 3. Ultimate Heat Sink
The following heat loads must be taken into consideration regarding the ultimate
heat sink: reactor core decay heat from radioactive decay and shutdown fission, spent fuel
decay heat, stored heat, heat rejected from items important to safety, and other accidentrelated heat sources such as chemical reactions (IAEA, 1981). Groundwater offers a
potential alternative cooling water source for systems and components important to
safety, even though it has not been commonly used for this purpose. However, the
sustained yield of the aquifer must be determined if groundwater is to be used; in
addition, the effect on connected surface water bodies, potential land subsidence,
groundwater supply interruptions and seismic effects should be considered (IAEA, 1984).
Relevant regulations or laws concerning environmental protection may dictate or prohibit
use of certain available heat sinks; therefore, it may be necessary to request an exemption
from these regulations or laws, on the grounds that the heat sink is needed for safety
purposes, and that its use would be limited to infrequent situations of limited duration
(IAEA, 1981).
Sharing of the ultimate heat sink between reactors at a multi-unit site is found to
be permissible providing that the following conditions are met: the simultaneous safe
shutdown and cool down of all the reactors they serve and their preservation in a safe
shutdown state; the dissipation of heat following an accident in one reactor, plus the
simultaneous safe shutdown and cool down of all remaining units and their preservation
in a safe shutdown state. Furthermore, where heat transport systems directly associated
with the ultimate heat sink are shared, account should be taken of the greater potential
consequences of failure of the system (IAEA, 2004).
In establishing the maximum heat rejection rate, the most severe combination of
individual heat loads should be identified for all postulated initiating events for which the
system is called upon to perform a normal operation or a safety function (IAEA, 2004).
In particular for the ultimate heat sink, the need for make-up of heat transport fluids
should also be examined. Where a limited quantity of heat transport fluids is stored on
site, the capability for make-up should be ensured by either: providing an adequate
quantity of such fluids to allow time to repair the damaged part of the make-up system, or
by protecting the make-up system from an external event. In case the make-up facilities

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cannot be fully protected, they should at least be dispersed or protected in such a way that
a minimum capacity remains immediately available after any external event (IAEA,
2003a).

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Appendix 4. Evaluating Sites for Nuclear Power Plants
The availability of large amounts of water is not the only factor considered in site
selection. The selection of an appropriate site is an important process since local
circumstances can affect safety. Choice of site may be approached in a prescriptive
manner, although more generally the choice of site is a balance between competing
factors including economic interests, public relations and safety (IAEA, 1999). In terms
of nuclear safety, the main objective in site evaluation for nuclear installation is to protect
the public and the environment from the radiobiological consequences of radioactive
releases due to accidents (IAEA, 2003e). The IAEA (2003e) outlines three aspects that
must be considered in the evaluation of the suitability of the site for a nuclear installation:
the effects of natural or human induced external events occurring in the region of the
particular site; the characteristics of the site and its environment that could influence the
transfer to persons and the environment of radioactive material that has been released;
and the population density, population distribution and other characteristics of the
external zone in so far as they may affect the possibility of implementing emergency
measures.
The likelihood of significant external events and their possible effects on nuclear
power plant safety must be determined from investigations of local factors. Moreover,
the hazard evaluation associated with extreme events has been extended from the siting
of the plants to the whole lifetime of the plant, including design, construction, operation
and decommissioning (IAEA, 2003b). Local factors that could adversely affect the safety
of the plant include geological and seismological characteristics, the potential for
hydrological and meteorological disturbances, and human induced factors such as aircraft
impact and explosions (IAEA, 1999, 2003e). In order to evaluate their possible extreme
values, the following meteorological variables must be documented for an appropriate
period of time: wind, precipitation, snow, temperature and storm surges. As well,
meteorological phenomena including tornadoes, tropical cyclones, blizzards, sand storms,
drought, icing and hail must be considered in the evaluation (IAEA, 2003d, 2003e).
Geotechnical hazards including: slope instability, collapse, subsidence or uplift of the site
surface, soil liquefaction (engineering solutions), behavior of foundation materials,
groundwater regime and chemical properties of the groundwater (IAEA, 2003e).

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Historical data concerning phenomena that have the potential to give rise to adverse
effects on the safety of the nuclear installations, such as volcanism, sand storms, severe
precipitation, snow, ice, hail, and subsurface freezing of subcooled water (frazil), shall be
collected and assessed (IAEA, 2003e). Installations that may give rise to wind-generated
missiles of any type that could affect the safety of the nuclear installation must be
evaluated. As well, potential effects of electromagnetic interference, eddy currents in the
ground and the clogging of air or water inlets by debris shall be evaluated (IAEA, 2003e).

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Appendix 5. External Events and Nuclear Power Plant
Design
Design must assure the protection of components vital to safety and continued
removal of heat from the core regardless of climate events. In the design of systems for
long term heat removal from the core, site related parameters, such as the following
should be considered: air temperature and humidity, water temperatures, available flow
of water, minimum water level and the period of time for which safety related sources of
cooling water are at a minimum level, with account taken of the potential for failure of
water control structures (IAEA, 2003e). A loss of off-site power should be assumed
coincident with any extreme design basis external event if a direct or indirect causal
relationship cannot be excluded (IAEA, 2003a). Potential natural and human induced
events that could cause a loss of function of systems required for the long term removal
of heat from the core shall be identified, such as the blockage or diversion of a river, the
depletion of a reservoir, or an excessive amount of marine organisms (IAEA, 2003e).
Redundant paths, screens, or other provisions should be made to prevent the entrainment
of debris which might obstruct air and water intakes (IAEA, 2003a, 2004). Alternative
intakes might not suffice to prevent the blockage. For such events, a diverse ultimate
heat sink or intake system should be provided (IAEA, 2003a). In addition, an inspection
regime should be established which takes due account of the need for passive or active
control measures and consideration of the rate of growth of the biological matter (IAEA,
2003 a).
The long term capacity of the ultimate heat sink is ensured by means of designs
that provide immediate access to inexhaustible natural bodies of water or to the
atmosphere. For sites with such access, it should be demonstrated that sufficient capacity
exists to accept the heat load until the heat sink can be replenished. Consideration should
be given to factors that could delay the replenishment process such as: evaporation,
human induced events, plant accident conditions, and the availability of interconnections
and the complexity of the procedures for replenishment (IAEA, 2004). The locations and
sizes of intake and discharge structures should be carefully evaluated in terms of yearly
temperature excursions, and the recorded patterns and effects of biofouling and of the
buildup of sand and silt on the effectiveness and performance of the proposed design.
Depending on the site characteristics, the need for a backup ultimate heat sink should be

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carefully assessed (IAEA, 2004).
The associated systems to the reactor coolant system must also be considered in
the design basis accident. The connected and associated systems mitigate the
consequences of design basis accidents and hence they are considered safety systems.
Associated systems are systems that are essential for the reactor coolant system and
connected systems including the component cooling water system, intermediate cooling
circuits, and essential service water system (IAEA, 2004). The system should be so
designed and laid out that no external event or internal hazard considered in the design
has the potential to prevent it from performing its intended safety functions (IAEA,
2004).
The design of the reactor coolant system and associated systems is influenced by
external events such as fires, earthquakes, wind-generated missiles, floods and other
natural phenomena, since these events could lead to a postulated initiating events (IAEA,
2004). Floods in particular have the potential to affect water intakes and thereby affect
safety related items. Flood considerations include sedimentation of the material
transported by the flood, erosion of the front water side, blockage of intakes by ice,
biological fouling by animals, and salt corrosion (IAEA, 2003c).
The design basis flood is derived from the analysis of all the possible flooding
scenarios at the site (IAEA, 2003c). The design basis flood is a series of parameters that
maximize the challenge to plant safety. For coastal sites the flood hazard is related to the
most severe among the following types of flood: probable maximum storm surge,
maximum tsunami (earthquake or landside), maximum seiche, wind and wave either
independent or in combination. A conservatively high reference water level is considered
for each of the cases to allow for tides, sea level anomalies, river flow, and surface runoff
(IAEA, 2003c). The expected average level of the seawater for the lifetime of the plant
should be appropriately documented with its confidence interval (IAEA, 2003d).
Upstream water control structures must also be analyzed to determine whether the
nuclear installation would be able to withstand the effects resulting from the failure of
one or more of the upstream structures (IAEA, 2003e). The potential for flooding due to
one or more natural causes should also be determined. Parameters to characterize the
hazards due to flooding shall include the height of the water, the height and period of the
waves, the warning time for the flood, the duration of the flood and the flow conditions

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(IAEA, 2003c, 2003e). In addition to food analysis, a preliminary investigation should be
undertaken to determine whether there is a potential for instability of the shoreline or
riverbank since erosion over the lifetime of the nuclear power plant could affect items
important to safety. Erosion maps and tidal current maps, aerial photographs and satellite
images are very useful and should be used where possible for studying erosion over large
areas (IAEA, 2003c).
Several options exist for flood protection and each should be evaluated. All
items important to safety should be constructed above the level of the design basis flood,
which can be accomplished by locating the plant at a sufficiently high elevation or by
means of construction arrangements that raise the ground level at the site (the 'dry site'
concept). In addition, permanent external barriers such as levees, sea walls and
bulkheads may be constructed. The barriers should be considered features important to
safety; therefore, care should be taken that appropriate design bases are selected for the
barriers and that periodic inspections, monitoring and maintenance of the barriers are
conducted (IAEA, 2003c). Sea walls, breakwaters, and revetments should be properly
designed to prevent soil erosion, flooding and structural failures which may jeopardize
the safety of important facilities. Potential failure of these structures from external events
must be assessed. If hazardous effects are expected, appropriate countermeasures should
be taken to protect the facility or otherwise the site layout should be reconsidered (IAEA,
2004).
As a redundant measure against flooding of the site, the protection of the plant
against extreme hydrological phenomena should be augmented by waterproofing, and by
appropriate design of all items necessary to ensure the capability to shut down the reactor
and maintain it in a safe shutdown condition. All other structures, systems and
components important to safety should be protected against the effects of a design basis
flood (IAEA, 2003c). Special operational procedures should be specified on the basis of
real time monitoring data on the identified causes of the flooding. A warning system
should be available that is able to detect potential flooding of the site with sufficient time
to complete the safe shutdown of the plant together with the implementation of adequate
emergency procedures. The warning system and all other items important to safety
should be designed to withstand the flood producing conditions (IAEA, 2003c).
In order to provide additional defense to the basic forms of protection, active or

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administrative measures based on forewarning can also provide safety benefits for some
external events. For instance, the installation of additional barriers or the closure of
watertight gates in anticipation of flooding, or the inspection of drainage channels may be
utilized. The reliability of such measures should be balanced with the reliability of the
monitoring, forecasting equipment and the operator (IAEA, 2003a). In designing for
additional protection, it should be borne in mind that barriers can introduce difficulties
for inspection and maintenance, while a greater spread in plant layout may require more
staff to handle the increased task of surveillance (IAEA, 2003a).
A safety classification is in place to ensure that those features needing extra
protection are protected in a design basis event. In addition to the safety classification,
the external event (EE) classification is a process that associates an external event
category to any plant item according to its required performance during and after a design
basis external event (IAEA, 2003a). Safety limits specified in safety classification
represent the design basis conditions for the items. Exceeding safety limits challenges
plant safety and therefore a plant shutdown is required with precise post-event
revalidation. Limits and conditions for normal operation should be identified in the
hazard evaluation phase to ensure prompt action (IAEA, 2003a).
Systems that should be classified as EE-C1 include: the reactor system
containment structure or the external shielding structure; structures supporting, housing,
or protecting items important to safety; structures protecting the plant from external
events; the power and instrumentation and control cables relevant to safety related items;
the control room or the supplementary control points; systems or portions of systems that
are required for monitoring, actuating and operating those parts of systems protected
against design basis external events; the emergency power supplies and their auxiliary
systems necessary for the active safety functions and the post-accident monitoring
system. Systems that should be classified as EE-C2 are those components whose
continued functionality is not required, but whose failure could reduce the functional
capability of any plant features specified as EE-C1 or could result in incapacitating injury
to occupants of the control room. Systems that should be classified as EE-C3 include:
components for spent fuel confinement; spent fuel cooling systems; systems for the
containment of highly radioactive waste in gaseous, vapor, liquid and/or solid form. The
EE classification can exclude items not affected by any design basis external event, for

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instance items located an elevation higher than the flood level in the cases of a design
basis flood (IAEA, 2003a).
The classification determines the level of protection given to each item. EE-C1
items should be designed, installed and maintained in accordance with engineering
practice for nuclear applications, for which appropriate safety margins should be
established according to the associated consequences. For any item in Category 1, an
appropriate acceptance criterion should be established (e.g. functionality, leaktightness
and maximum distortion) according to the required safety function (IAEA, 2003a). EEC2 items have a more simplified and less conservative criteria for design, installation and
maintenance may be used, and in some cases a lower intrinsic safety margin than for EEC1 items and in relation to their probability of being the initiator of an accident. Often,
experience based walk downs are implemented in response to this concern (IAEA,
2003a). EE-C3 items should be designed, installed and maintained in accordance with
engineering practice for nuclear applications, but generally the criteria are less
conservative than those defined for EE-C1 (IAEA, 2003a).
Rare meteorological events such as lightning, tornadoes, and tropical cyclones
must be evaluated for the site (IAEA, 2003e). The potential for occurrence of tornadoes
is assessed on the basis of detailed historical and instrumentally recorded data for the
region. The hazards associated with tornadoes are expressed in terms of rotational wind
speed, translational wind speed, radius of maximum rotational wind speed, pressure
differentials and rate of change of pressure, and potential wind-generated missiles. The
following data on the storm parameters for tropical cyclones should be collected:
maximum central pressure, maximum wind speed, horizontal surface wind profile, shape
and size of the eye, vertical temperature and humidity profiles within the eye,
characteristics of the tropopause over the eye, positions of the tropical cyclone at regular
preferably six hourly, intervals, and sea surface temperature (IAEA, 2003d, 2003e).

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Appendix 6. New Reactor Design and Research Goals
Reactors are categorized by generation. The first generation was advanced in the
1950s and 60s in the early prototype reactors. The second generation began in the 1970s
in the large commercial power plants that continue to operate today. Reactors in the third
generation were developed more recently in the 1990s and promise advances in safety
and economics. These reactors have been built primarily in East Asia. Advances to
Generation III have resulted in Generation III+ reactors that are actively under
development and deployable in the near-term. Plants built between now and 2030 will be
chosen from Generation III+ reactors. Generation III+ reactors include: several types of
advanced boiling water and pressurized water reactors, advanced heavy water reactors
and gas cooled reactors such as the Gas Turbine–Modular High Temperature Reactor and
Pebble Bed Modular Reactor (PBMR).
Argentina, Brazil, Canada, France, Japan, the Republic of Korea, the Republic of
South Africa, Switzerland, the United Kingdom, and the United States joined together to
form the Generation IV International Forum (GIF) to develop future-generation nuclear
energy systems that can be licensed, constructed, and operated in a manner that will
provide competitively priced and reliable energy products while addressing concerns
pertaining to nuclear safety, waste, proliferation, and public perception (U.S. DOE
Nuclear Energy Research Advisory Committee and the Generation IV International
Forum, 2002). The objective for Generation IV nuclear energy systems is to have them
available for international deployment by the year 2030, when many of the worlds’
currently operating nuclear power plants will be at or near the end of their operating
licenses. The GIF decided to focus on research and development of six reactors: GasCooled Fast Reactor System (GFR), Lead-Cooled Fast Reactor System (LFR), Molten
Salt Reactor System (MSR), Sodium-Cooled Fast Reactor System (SFR), SupercriticalWater-Cooled Reactor System (SCWR), and Very-High-Temperature Reactor System
(VHTR). The reactors chosen include those with closed fuel cycles, open fuel cycles, or
both. In an open fuel cycle discharged fuel is sent directly to disposal, while in a closed
fuel cycle waste products are separated from unused fissionable material that is recycled
as fuel into reactors. The GIF ranked each reactor according to goals in the categories of
sustainability, economics, safety and reliability, and proliferation resistance.

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Table 1. Goals of Generation IV nuclear power plants (U.S. DOE Nuclear Energy Research
Advisory Committee and the Generation IV International Forum, 2002).
Category
Goal
Sustainability
Provide sustainable energy generation that meets clean air
objectives and promotes long-term availability of systems and
effective fuel utilization for worldwide energy production.
Sustainability
Minimize and manage their nuclear waste and notably reduce the
long-term stewardship burden, thereby improving protection for the
public health and the environment.
Economics
Clear life-cycle cost advantage over other energy sources.
Economics
A level of financial risk comparable to other energy projects.
Safety and Reliability Operations will excel in safety and reliability.
Safety and Reliability Have a very low likelihood and degree of reactor core damage.
Safety and Reliability Eliminate the need for offsite emergency response.
Proliferation
Increase the assurance that the nuclear power plants are a very
Resistance
unattractive and the least desirable route for diversion or theft of
and Physical
weapons-usable materials, and provide increased physical
Protection
protection against acts of terrorism.

In particular, actinide management is a mission with significant societal benefits
because it insures both nuclear waste consumption and long-term assurance of fuel
availability. Actinides are the elements produced during a nuclear reaction with atomic
numbers (Z) greater than or equal to that of actinium (Z = 89). Some actinides are fissile
and can be used as nuclear fuel in other reactors; moreover, many of the actinides have
long half-lives, complicating the problems of nuclear waste disposal (Bodansky, 2004).
Although Generation IV systems for actinide management aim to generate
electricity economically, the market environment for these systems is not yet well defined
(U.S. DOE Nuclear Energy Research Advisory Committee and the Generation IV
International Forum, 2002). All designs include untested engineering, and also depend on
the development of new materials that can resist continued high temperatures, intense
bombardment by neutrons in the chain reaction, and often corrosive reagents (Butler,
2004). The uncertainty of the outcome of research and development, and the large
uncertainty in projecting production and capital costs several decades into the future
make the evaluation of economics for each of the reactors difficult (U.S. DOE Nuclear
Energy Research Advisory Committee and the Generation IV International Forum, 2002).

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Appendix 7. Nuclear Power as a Mitigation Measure for
Climate Change
The World Nuclear Association (2007) estimates that currently 2.6 billion tons
of CO2 per year (GtC/year) is avoided because of nuclear power. While nuclear power
does not generate greenhouse gases during direct energy production, considering the
entire fuel cycle leads to different estimates in the amount of emissions associated with
nuclear power. The entire fuel cycle includes uranium mining, enrichment, power plant
construction, and decommissioning all of which require the burning of fossil fuels. An
additional source is chemical reactions particularly the production of cement and steel
(Storm van Leeuwen & Smith, 2005).
One important difference in the amount of greenhouse gases generated for
nuclear power is the enrichment process used. For instance, most enrichment in the
United States utilizes the gas diffusion process whereas centrifuge enrichment is
predominant in Europe (Andseta et al., 2000). The gaseous diffusion process consumes
about 2500 kWh/SWU (separation work unit), while modern gas centrifuge plants require
only about 50 kWh/SWU (World Nuclear Association, 2008e). The large difference
emphasizes the importance of enrichment process efficiency in overall determination of
CO2 releases per unit electrical energy output.
Choosing more efficient enrichment processes is an important consideration in
reducing the greenhouse gas emitted during the nuclear fuel cycle. The mining of
uranium is another matter that could reduce the potential for nuclear power to mitigate for
climate change in the long-term. Storm van Leeuwen and Smith (2005) emphasize that
due to the declining ore grade over time, the CO2 emission will rise gradually. Up until
today, uranium has been extracted from easily mined and relatively rich uranium ores.
The largest uranium resources of the world, however, exist in far leaner ores which are
more difficult to mine than in the past. When very poor ores are to be exploited, the CO2
emissions will rise exponentially and surpass that of gas-fired electricity generation and
any fossil-fuelled power system (Storm van Leeuwen & Smith, 2005).
Therefore, in the long term (fifty to a hundred years) a significant reduction in
CO2 emissions, worldwide, via use of nuclear power, will require reactors that utilize a
much larger fraction of the energy content of uranium than do most of the reactors in use

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today, or would require economical extraction of uranium from ores much leaner than
those presently used (Perry & Weinberg, 2001). In the near term nuclear power plants
could not play a significant role to reduce carbon dioxide emissions because they operate
near their maximum output already and cannot provide much incremental output
(Paffenbarger, 1998). For instance, in the U.S. new plants could not make a substantial
contribution to reducing U.S. global warming emissions for at least two decades even
under an ambitious deployment scenario (Union of Concerned Scientists, 2007).
Measures that offer near-term reductions are needed such as efficiency measures,
conservation, and removal of barriers to existing technologies.
In addition, nuclear power as a mitigation option shifts the focus to developing
technologies that address supply, while many solutions are available on the demand side
of the energy problem. Nuclear proponents point to the need for high-volume,
concentrated energy sources for sustained economic growth in urban populations
(Nuclear Energy Institute, 2007). However, many developing countries have an
opportunity since they are not locked-in to a centralized grid. Centralized grids are
inefficient and costly with energy losses of 8% along long-distance transmission lines
(Butler, 2007). The grid is often congested because it relies on a few high-traffic arteries.
The congestion amplifies the inefficiency because if the utility cannot redirect power
from efficient sources, they have to turn to costlier, dirtier and more inefficient sources to
meet peak demand (Butler, 2007). Utilizing multiple decentralized energy sources
allows electricity to be generated close to the point of use, avoiding the losses and
congestion that result from long-distance transmission (Butler, 2007). Technologies that
aid in developing efficient grids include smart meters that provide real-time data on grid
conditions, load and pricing. The meters help in the demand side by helping users
consume less energy, but also in the supply side by providing better ways to handle the
intermittent and distributed nature of alternative energy sources grids (Butler, 2007).

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Appendix 8. Coastal Vulnerability Methods
The methods described here were used to determine relative Coastal
Vulnerability in the United States by Thieler and Hammar-Klose (1999a; 1999b; 2000).
The geomorphology variable expresses the relative erosion rates of different landform
types. These data were derived from state geologic maps and USGS 1:250,000 scale
topographic maps. The regional slope of the coastal zone was calculated from a grid of
topographic and bathymetric elevations extending approximately 50 km landward and
seaward of the shoreline. Relative sea level change over the past 50-100 years were
obtained for 28 National Ocean Service (NOS) data stations and contoured along the
coastline. Shoreline erosion and accretion rates for the U.S. were taken from the Coastal
Erosion Information System (CEIS). The data in CEIS are drawn from a wide variety of
sources, including published reports, historical shoreline change maps, field surveys and
aerial photo analyses.
Tide range data were obtained from the National Ocean Service’s 657 tide
stations along the U.S. coast, and their values contoured along the coastline. Typically a
large tidal range is associated with higher coastal vulnerability. This study inverted the
ranking, because a small tidal range means the site is always near high tide, and therefore,
always at risk of inundation from storms.
Wave height was used as an indicator of wave energy, which drives the coastal
sediment budget. Hindcast nearshore mean wave height data for the period 1976-1995
was obtained from the U.S. Army Corps of Engineers Wave Information Study (WIS).
The model wave heights were compared to historical measured wave height data obtained
from the NOAA National Data Buoy Center. Wave height data for 151 WIS stations
along the U.S. coast were contoured along the coastline.
Numerical variables are assigned a risk ranking based on data value ranges as
shown in Table 1 and 2 for the Atlantic and Pacific respectively. The non-numerical
geomorphology variable is ranked according to the relative resistance of a given landform
to erosion. The coastal vulnerability index is calculated as the square root of the
geometric mean, or the square root of the product of the ranked variables divided by the
total number of variables as in the following equation:

CVI = SQRT( ( a*b*c*d*e*f ) / 6 )

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where, a = geomorphology, b = coastal slope, c = relative sea level rise rate, d = shoreline erosion/accretion rate, e = mean tide
range, and f = mean wave height.
Table 1. Ranking of coastal vulnerability index for the Atlantic and Gulf coasts.
Ranking
Variable
Very Low 1
Low 2
Moderate 3
High 4
Cobble
Geomorphology
Rocky cliffs, Medium cliffs,
Low cliffs,
fjords
indented coasts Glacial drift, beaches,
Alluvial plains Estuary,
Lagoon
>0.115
0.115 – 0.055 0.055 – 0.035 0.035 – 0.022
Coastal Slope (%)
Relative sea-level change (mm/yr)
<1.8
1.8 – 2.5
2.5 – 3.0
3.0 – 3.4
Shoreline erosion/accretion (m/yr)
>2.0
1.0 – 2.0
-1.0 – 1.0
-1.1 – -2.0
Mean tide range (m)
>6.0
4.1 – 6.0
2.0 – 4.0
1.0 – 1.9
Mean wave height (m)
<0.55
0.55 – 0.85
0.85 – 1.05
1.05 – 1.25

Very High 5
Barrier beaches, Sand
beaches, Salt marsh, Mud
flats, Deltas, Mangrove,
Coral reefs
<0.022
>3.4
<-2.0
<1.0
>1.25

Table 2. Ranking of coastal vulnerability index for the Pacific coast.
Ranking
Very Low 1
Low 2
Moderate 3
High 4
Rocky cliffs, Medium cliffs,
Low cliffs,
Cobble
Fjords
Indented coasts Glacial drift, beaches,
Alluvial plains Estuary,
Lagoon
Coastal Slope (%)
>1.9
1.3 – 1.9
0.9 – 1.3
0.6 – 0.9
Relative sea level change (mm/yr)
<-1.21
-1.21 – 0.1
0.1 – 1.24
1.24 – 1.36
>2.0
1.0 – 2.0
-1.0 – 1.0
-1.1 – -2.0
Shoreline erosion/accretion (m/yr)
Mean tide range (m)
>6.0
4.1 – 6.0
2.0 – 4.0
1.0 – 1.9
Mean wave height (m)
<1.1
1.1 – 2.0
2.0 – 2.25
2.25 – 2.6
Variable
Geomorphology

Very High 5
Barrier beaches, Sand
beaches, Salt marsh, Mud
flats, Deltas, Mangrove,
Coral reefs
<0.6
>1.36
<-2.0
<1.0
>2.6

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Appendix 9. Coastal Vulnerability Data
Table 1 and Table 2 provide the actual values for site variables at each of the sites on the Atlantic and Pacific coasts respectively.
Table 1. Summary of coastal variables for each site on the Atlantic coast. * Indicates an average value for those sites that have two different
coastal segments.
Reactor
Mean tidal range (m) Coastal Slope % Erosion/Accretion (m/yr) Mean Wave Height (m)
Seabrook
2.460
0.19840*
-0.500
1.2
Pilgrim
2.990
0.19410
4.500
0.9
Millstone
0.790
0.24990
-0.700
0.9
Calvert Cliffs
0.400
0.10
-6.4
0.9
Saint Lucie (coast)
0.800
0.00108
-0.600
1.2
Saint Lucie (river)
0.800
0.00108
-0.600
1.2
Turkey Point
0.500
0.00108
-0.100
0.9
Crystal River
0.890
0.05977
-2.000
0.4
Table 2. Summary of coastal variables for sites on the Pacific coast. * Indicates an average value for those sites that have two different coastal
segments.
Reactor
Mean tidal range (m)
Coastal Slope % Erosion/Accretion (m/yr) Mean Wave Height (m)
Diablo Canyon
1.12
1.1002
-0.30
1.3
San Onofre
1.12
1.5626*
-0.46
0.7

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