# U.S. Spent Nuclear Fuel Storage

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URL: https://www.frixlaw.com/law-library/documents/crs%3AR42513

## Record

- **Collection:** Congressional research report
- **Document type:** CRS Report
- **Published:** May 24, 2012
- **Citation:** R42513

## Text

U.S. Spent Nuclear Fuel Storage
(name redacted)
Section Research Manager
May 24, 2012

Congressional Research Service
7-....
www.crs.gov
R42513

CRS Report for Congress
Prepared for Members and Committees of Congress

U.S. Spent Nuclear Fuel Storage

Summary
Regardless of the outcome of the ongoing debate about the proposed Yucca Mountain geologic
waste repository in Nevada, the storage of spent nuclear fuel (SNF)—also referred to as “highlevel nuclear waste”—will continue to be needed and the issue will continue to be debated. The
need for SNF storage, even after the first repository is opened, will continue for a few reasons.
•

The Obama Administration terminated work on the only planned permanent
geologic repository at Yucca Mountain, which was intended to provide a
destination for most of the stored SNF. Also, the Yucca Mountain project was not
funded by Congress in FY2011 and FY2012, and not included in the
Administration’s budget request for FY2013.

•

Even if the planned repository had been completed, the quantity of SNF and
other high-level waste in storage awaiting final disposal now exceeds the legal
limit for the first repository under the Nuclear Waste Policy Act (NWPA).

•

The expected rate of shipment of SNF to the repository would require decades to
remove existing SNF from interim storage. Accordingly, the U.S. Nuclear
Regulatory Commission (NRC) and reactor operators are considering extended
SNF storage lasting for more than 100 years.

The debate about SNF typically involves where and how it is stored, as well as what strategies
and institutions should govern SNF storage. The earthquake and tsunami in Japan, and resulting
damage to the Fukushima Dai-ichi nuclear power plant, caused some in Congress and NRC to
consider the adequacy of protective measures at U.S. reactors. The NRC Near-Term Task Force
on the disaster concluded it has “not identified any issues that undermine our confidence in the
continued safety and emergency planning of U.S. plants.” Nonetheless, NRC has accepted a
number of staff recommendations on near-term safety enhancement, including requirements
affecting spent fuel storage and prevention and coping with station blackout. NRC is not
requiring accelerated transfer of SNF from wet pools to dry casks, but the SNF storage data from
the last several years indicate that accelerated transfer has already been occurring.
As of December 2011, more than 67,000 metric tons of SNF, in more than 174,000 assemblies, is
stored at 77 sites (including 4 Department of Energy (DOE) facilities) in the United States located
in 35 states (see Table 1 and Figure 5), and increases at a rate of roughly 2,000 metric tons per
year. Approximately 80% of commercial SNF is stored east of the Mississippi River. At 9
commercial SNF storage sites there are no operating nuclear reactors (so-called “stranded” SNF),
and at the 4 DOE sites reactor operations largely ceased in the 1980s, but DOE-owned and some
commercial SNF continues to be stored at DOE facilities. In the United States, SNF is stored
largely at nuclear reactor sites where it was generated. Of the 104 operating nuclear reactors in
the United States, all necessarily have wet storage pools for storing SNF (wet pools are required
to allow for a safe “cooling off” period of 1 to 5 years after discharge of SNF from a reactor). Wet
storage pools are used for storage of approximately 73% (49,338 out of 67,450 metric tons of
uranium, or MTU) of the current commercial SNF inventory, whereas the remaining 27% (18,112
MTU) of commercial SNF is stored in dry casks on concrete pads or in vaults. As wet storage
pools become filled to capacity using “dense packing” storage methods, dry storage is
increasingly being used, although there are 27 sites with 36 wet storage pools with no current dry
cask storage capabilities.

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U.S. Spent Nuclear Fuel Storage

This report focuses on the current situation with spent nuclear fuel storage in the United States. It
does not address all of the issues associated with permanent disposal of SNF, but rather focuses
on the SNF storage situation, primarily at current and former reactor facilities for the potentially
foreseeable future.

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U.S. Spent Nuclear Fuel Storage

Contents
Introduction...................................................................................................................................... 1
What Is Spent (Used) Fuel? ............................................................................................................. 9
How Is Spent Fuel Stored Now?.................................................................................................... 12
Where Is Spent Nuclear Fuel Located Now in the United States? ................................................ 17
SNF Management by the U.S. Department of Energy................................................................... 26
Hazards and Potential Risks Associated with SNF Storage........................................................... 29
Options for Storing Spent Nuclear Fuel......................................................................................... 37
Options for How to Store SNF ................................................................................................ 38
Options for Where to Store SNF.............................................................................................. 43
Options for SNF Management and Regulatory Oversight ...................................................... 45
Issues for Congress ........................................................................................................................ 48

Figures
Figure 1. Nuclear Fuel Assembly .................................................................................................. 10
Figure 2. SNF Storage Pool Location in Boiling Water Reactor ................................................... 13
Figure 3. PWR SNF Storage Pool Location .................................................................................. 14
Figure 4. Example of Dry Cask Storage ........................................................................................ 16
Figure 5. Spent Nuclear Fuel Storage Map.................................................................................... 23

Tables
Table 1. U.S. Spent Nuclear Fuel Storage Inventories by State (Ranked by Total SNF
Mass) .......................................................................................................................................... 19
Table A-1. Alphabetical List of 35 States Where Spent Nuclear Fuel is Stored ............................ 50

Appendixes
Appendix. U.S. Spent Nuclear Fuel Storage Inventories............................................................... 50

Contacts
Author Contact Information........................................................................................................... 53

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U.S. Spent Nuclear Fuel Storage

Introduction
Recent events have renewed long-standing congressional interest in safe management of spent
nuclear fuel (SNF) and other high-level nuclear waste.1 These issues have been examined and
debated for decades, sometimes renewed by world events like the 9/11 terrorist attacks. The
incident at the Fukushima Dai-ichi nuclear reactor complex in Japan, combined with the
termination of the Yucca Mountain geologic repository project,2 have contributed to the increased
interest.
This report focuses on the current situation with spent nuclear fuel storage in the United States. It
does not address all of the issues associated with permanent disposal of SNF, but rather focuses
on the SNF storage situation, primarily at current and former reactor facilities and former reactor
sites for the potentially foreseeable future (i.e., a total of 300 years).3
Although no nation has yet established a permanent disposal repository for SNF and other forms
of high-level radioactive waste (HLW), there is broad consensus that a geological repository is
the preferred method for these wastes.4 In the United States, the disposal repository location has
been debated for decades. The proposed repository in Nevada at Yucca Mountain was terminated
in 2009, although the project continues to be debated and litigated. Whether the current situation
with the Yucca Mountain project is merely a temporary hiatus or becomes a permanent shutdown,
extended storage for longer than previously anticipated is virtually assured. There is also no clear
consensus on interim storage of SNF. The SNF storage issues most widely debated include
•

What strategies should be employed for SNF storage, pending disposal;

•

Where should SNF be stored on an interim basis; and

•

What SNF management structure should be used?

1
“Spent Nuclear Fuel” (SNF) is sometimes referred to as “used” nuclear fuel. This difference in terminology often
reflects a significant policy debate about whether SNF is a waste destined for disposal, or a resource. This report uses
the term SNF to be consistent with other independent agency documentation. The broader term, “nuclear waste,” which
is sometimes used to refer to SNF, is generally not used here to avoid imprecision and confusion with other waste
forms (e.g., low-level or transuranic waste and naturally occurring radioactive materials). Although they are quite
different technically, spent nuclear fuel and liquid raffinate waste from reprocessing are both defined legally under the
Nuclear Waste Policy Act (NWPA) as “high-level waste.” See 42 U.S.C. 10101(2)(12) and 10 C.F.R. 60.2, 10 C.F.R.
63.2, and 40 C.F.R. 197.2.
2
House Energy and Commerce Committee; Environment Subcommittee Hearing, “DOE’s Role in Managing Civilian
Radioactive Waste,” June 1, 2011, http://energycommerce.house.gov/news/PRArticle.aspx?NewsID=8710; and House
Energy and Commerce Subcommittee on Environment and the Economy, “Bipartisan Concern Over Administration’s
Haste to Terminate Permanent Nuclear Repository,” press release, June 15, 2011.
3
See CRS Report R40202, Nuclear Waste Disposal: Alternatives to Yucca Mountain, by (name redacted); and CRS Report
RL33461, Civilian Nuclear Waste Disposal, by (name redacted), for discussion of related issues.
4
See, e.g., National Research Council, Board on Radioactive Waste Management, Rethinking High-Level Radioactive
Waste Disposal: A Position Statement of the Board on Radioactive Waste Management (1990), p. 2. National
Academies/National Research Council/Board on Radioactive Waste Management, Disposition of High-Level Waste
and Spent Nuclear Fuel: The Continuing Societal and Technical Challenges, National Academy Press, Washington,
DC, 2001; Massachusetts Institute of Technology, The Future of the Nuclear Fuel Cycle: An Interdisciplinary MIT
Study, MIT, Cambridge, MA, 2011; and Matthew Bunn, et al., Interim Storage of Spent Nuclear Fuel: A Safe, Flexible,
and Cost-Effective Near Term Approach to Spent Nuclear Fuel Management, Harvard Press, Cambridge, MA, Harvard
University Project on Managing the Atom and University of Tokyo Project on Nuclear Energy, 2001,
http://belfercenter.ksg.harvard.edu/files/spentfuel.pdf.

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A focus of this renewed broader debate is the recently completed report by the Blue Ribbon
Commission on America’s Nuclear Future (BRC), which released its final report on January 29,
2012.5 This final report modified a July 2011 draft, which followed nearly more than a year of
effort, including extensive public testimony and several subcommittee reports after the
Commission was chartered by the Secretary of Energy in early 2010.6
Some, including the U.S. Nuclear Regulatory
Commission (NRC), view the current situation
as providing adequate safety. Others,
including the National Academy of Sciences,
have observed that safety may be improved by
wider use of dry storage methods. Some
analysts, including the BRC, have considered
issues beyond safety—including cost and
impact on investments—and urge construction
of an interim centralized storage at a
“volunteer” location after sufficient cooling
has occurred.7
Some have recommended a more limited
approach to consolidation of interim SNF
storage using a smaller number of existing
operational reactor sites, away from the
original generating reactor, for SNF located
where there is no operating reactor generating
additional SNF or if repository delays result in
greater stranded SNF and higher financial
liabilities.8 The two primary technologies
being employed in the United States are wet
pool storage and dry cask storage (see “How
Is Spent Fuel Stored Now?”).

Spent Nuclear Fuel (SNF) In Brief
•
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•
•
•
•
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•
•
•
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•
•

Commercial SNF is composed of metal assemblies
about 12’-15’ long (Figure 1).
SNF contains uranium and elements created in
nuclear reaction.
SNF assemblies are removed from reactors after
being used to produce power.
Existing reactors generate about 2,000 metric tons
per year.
More than 67,000 metric tons of commercial SNF is
currently being stored.
Most SNF is stored at 77 sites in 35 states (see
Figure 5).
Some SNF is stored at closed reactors.
Some SNF is stored at Department of Energy
(DOE) facilities.
Only 4% of the SNF in the United States is DOEowned.
SNF is stored in wet pools and dry casks.
SNF storage at reactors was intended to be
temporary, pending disposal.
No nation operates a disposal site for SNF.
Proposed U.S. disposal site for SNF at Yucca
Mountain in Nevada was terminated in 2009.
SNF storage is expected to be needed for more
than 100 years.

5
Blue Ribbon Commission on America’s Nuclear Future, Report to the Secretary of Energy, January 2012,
http://brc.gov/sites/default/files/documents/brc_finalreport_jan2012.pdf.
6
Blue Ribbon Commission on America’s Nuclear Future, U.S. Department of Energy, Advisory Committee Charter,
filed with Congress March 1, 2010. See http://brc.gov/index.php?q=page/charter.
7
Kraft, Steven P., “Used Nuclear Fuel Integrated Management,” Nuclear Energy Institute, Presentation to National
Association of Regulatory Utility Commissioners (NARUC), February 13, 2010; Redmond, Everett, “Nuclear Energy
Institute Comments on the Disposal Subcommittee Draft Report to the Blue Ribbon Commission on America’s Nuclear
Future,” July 1, 2011 (see http://brc.gov/sites/default/files/comments/attachments/
comments_of_nuclear_energy_institute_-_july_1_2011.pdf), and Kraft, Steven P., “Used Nuclear Fuel Integrated
Management,” Nuclear Energy Institute, Presentation to National Association of Regulatory Utility Commissioners
(NARUC), February 13, 2010.
8
Cochran, Thomas B. (Natural Resources Defense Council, Inc.), “Statement on the Fukushima Nuclear Disaster and
its Implications for U.S. Nuclear Power Reactors,” Joint Hearings of the Subcommittee on Clean Air and Nuclear
Safety and the Committee on Environment and Public Works, U.S. Senate, April 12, 2011, and American Physical
Society Nuclear Energy Study Group, Consolidated Interim Storage of Commercial Spent Nuclear Fuel: A Technical
and Programmatic Assessment, February 2007.

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Senator Dianne Feinstein, chair of the Senate Subcommittee on Energy and Water Development
Appropriations, with jurisdiction over NRC and the U.S. Department of Energy (DOE), stated at
a hearing in March 2011:
Most significantly, I believe we must rethink how we manage spent fuel. Spent fuel must
remain in pools for at least five to seven years, at which time it can be moved to safer dry
cask storage. However, these pools often become de facto long-term storage, with fuel
assemblies “re-racked” thus increasing the heat load of the pools. In California, for instance,
fuel removed from reactors in 1984 is still cooling in wet spent fuel pools.... Reports out of
Japan indicate there were no problems with the dry casks at Dai-ichi. To me, that suggests
we should at least consider a policy that would encourage quicker movement of spent fuel to
dry cask storage.9

Senator Feinstein followed up this hearing statement with a formal letter to the NRC chairman
asking NRC “to seriously consider regulatory policies that would encourage the movement of
nuclear fuel, once sufficiently cool, out of spent fuel pools and into dry cask storage systems.”10
Citing the 2006 study by the National Academy of Sciences (NAS) National Research Council
(Safety and Security of Commercial Spent Nuclear Fuel Storage), Senator Feinstein specifically
asked the “NRC to initiate a rulemaking process to immediately require a more rapid shift of
spent fuel to dry casks.”11 Senator Feinstein indicated her concern about spent fuel management
in evaluating proposals for funding small modular reactors.12 NRC subsequently considered SNF
storage needs a part of its Near-Term Task Force on the Fukushima Dai-ichi incident.
A House Appropriations Subcommittee report recently expressed concern about current spent fuel
storage, indicating that “[c]onsolidation of this material in a single site that provides enhanced
safety and security will improve public comfort with nuclear power, reduce potential safety and
security risk, and fulfill the federal government’s obligation under the Nuclear Waste Policy Act
of 1982 to assume responsibility of spent fuel.”13 Although consolidated interim storage of SNF
has received widespread support as a general concept for many years, proposals for SNF storage
at specific locations have been vigorously opposed.14
The issue of SNF storage is inextricably linked to related longer-term issues like nuclear power
plant operations and construction, SNF reprocessing, and establishment of a permanent
repository. This report is focused on SNF storage, and does not provide a detailed examination of
these related issues.15
9
Chairman Dianne Feinstein, Opening Statement, Hearing of the Senate Committee on Appropriations Subcommittee
on Energy and Water Development, “U.S. Nuclear Power Safety in Light of Japan Disaster,” March 30, 2011.
10
Senator Dianne Feinstein, Letter to Gregory Jaczko, Chairman of U.S. Nuclear Regulatory Commission, April 8,
2011.
11
Ibid.
12
Senator Dianne Feinstein, Safety and Economics of Light Small Water Modular Reactors, Statement at Hearing on
Light Small Water Modular Reactors, Senate Energy and Water Development Appropriations Subcommittee, June 14,
2011.
13
U.S. House Energy and Water Development Appropriations Subcommittee, 112th Congress Report; 1st Session;
Energy and Water Development Appropriations Bill Committee Report, 2012 (June 2011). Also see Committee on
Science, Space, and Technology, Majority Staff Report; “Yucca Mountain: The Administration’s Impact on U.S.
Nuclear Waste Management Policy,” June 2011.
14
See generally, Walker, J. Samuel (NRC Historian), The Road To Yucca Mountain: The Development of Radioactive
Waste Policy in the United States, University of California Press, 2009.
15
See CRS Report R40202, Nuclear Waste Disposal: Alternatives to Yucca Mountain, by (name redacted), and CRS Report
(continued...)

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Worldwide, there are 436 operational nuclear power reactors in 32 countries and 122 permanently
shut-down nuclear power reactors, including several in countries where SNF continues to be
stored after the reactor fleet has been shut down.16 No country, including the United States, has
yet established an operating permanent disposal site for SNF or other forms of high-level nuclear
waste. All nations rely—to varying degrees—on long-term SNF storage.17 Although the United
States has not fully addressed its nuclear waste issues, DOE has, since 1999, operated a
permanent geological repository for plutonium-contaminated transuranic (i.e., mainly plutoniumcontaminated)18 waste from nuclear weapons operations19 in New Mexico. Known as the Waste
Isolation Pilot Plant (WIPP), this waste disposal repository was constructed and began operations
following decades of detailed technical and institutional planning, active state and community
involvement,20 and compliance work to meet various federal and state environmental review and
permitting requirements.21 The WIPP site is explicitly prohibited by law from receiving SNF or
high-level waste, but is widely regarded as a model for other waste facility—both disposal and
storage—siting efforts. A recent survey of spent fuel storage in the 10 countries with significant
nuclear operations found that all countries store substantial amounts of SNF in pools or dry cask
facilities,22 regardless of their policy on reprocessing.23
(...continued)
RL34234, Managing the Nuclear Fuel Cycle: Policy Implications of Expanding Global Access to Nuclear Power,
coordinated by Mary Beth Nikitin.
16
International Atomic Energy Agency, Nuclear Power Reactors in the World, 2010 Edition (Reference Data Series
No. 2), IAEA, Vienna, Austria. See http://www-pub.iaea.org/MTCD/Publications/PDF/iaea-rds-2-30_web.pdf.
17
Finland (with four nuclear reactors) is the only country where a commercial nuclear waste repository site has been
selected with local government involvement and support, and characterization work has begun for a permanent highlevel radioactive repository. Sweden has operated an interim central SNF pool storage facility since 1985 at
Oskarshamn, and plans to develop a permanent geologic repository about 200 miles north at the Forsmark nuclear
power plant near Ӧsthammar, which has a right to veto the permit. France has a strongly supported nuclear power
program, but has not yet selected a disposal site for the high-level waste and SNF (approximately 13,500 MT of SNF
(as of 2007) and 2,229 cubic meters of vitrified high-level waste (as of 2007) were stored in France).
18
“Transuranic” waste is defined as alpha-emitting radioactive waste contaminated with radionuclides heavier than
uranium (atomic weight 93) at a concentration greater than 100 nCi/g (3.7 MBq/kg). The Waste Isolation Pilot Plant
Land Withdrawal Act as amended by P.L. 104-201 (H.R. 3230, 104th Congress).”
19
de Saillan, Charles, “Disposal of Spent Nuclear Fuel in the United States and Europe: A Persistent Environmental
Problem,” Harvard Environmental Law Review 34, 461 (2010).
20
See generally McCutcheon, Chuck, Nuclear Reactions, The Politics of Opening a Radioactive Waste Disposal Site,
University of New Mexico Press, 2002, ISBN-10: 0826322093.
21
The opening and operation of WIPP is given by some as evidence that the “nuclear waste problem” can be solved.
While recognizing the successful siting and permitting of WIPP, others note inherent uncertainty about long-term
performance. Also, some have suggested that the WIPP site be used later for disposal of high-level waste and spent
nuclear fuel, in addition to disposal of transuranic wastes for which it is currently dedicated. Such a change of mission
at WIPP would require, at a minimum, amending Section 12 of the WIPP Land Withdrawal Act, which provides a “ban
on high-level radioactive waste and spent nuclear fuel.” P.L. 102-579, 106 Stat. 4777.
22
An SNF storage “facility” is generally associated with a reactor (see Figure 2 and Figure 3), except in the case of
the Morris, IL, facility, which was initially built not as a power reactor, but as part of an SNF reprocessing facility that
never operated. In many cases there are more than one nuclear power reactor and SNF storage “facility” at a “site,”
which is a geographically contiguous area (see “Where Is Spent Nuclear Fuel Located Now in the United States?”).
Because dry cask storage areas are typically independent of a reactor facility at a site, dry cask storage is generally
quantified according to number of sites, not facilities.
23
Feiveson, Harold, Zia Mian, M.V. Ramana and Frank von Hippel, International Panel on Fissile Materials, “Spent
Fuel from Nuclear Power Reactors: An Overview of a New Study by the International Panel on Fissile Materials,”
September 2011. The study summarizes SNF management in the United States, Canada, France, Germany, Finland,
Japan, South Korea, Russia, Sweden, and the United Kingdom. France provides the greatest support for reprocessing its
SNF, but is listed as having the third highest amount of SNF (13,500 MT in 2007), behind the U.S. and Canada.

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Although much of the congressional attention has focused on the issues of the permanent
geological repository proposed for Yucca Mountain in Nevada, there are a number of reasons to
also consider SNF storage issues.
First, under any scenario for waste acceptance into a permanent repository or an interim
consolidated storage site, long-term storage of SNF will be required for a considerable time.
Notwithstanding the mandate in the Nuclear Waste Policy Act (NWPA) and various contracts that
DOE begin accepting SNF for disposal in 1998, no disposal repository has been completed or
licensed. The 2009 termination of the Yucca Mountain disposal project continues the ongoing
delay in opening a permanent geologic repository.24 Hence, the disposal delay prolongs storage
needs.
Even if a disposal repository were to begin operation quickly, the time required to ship SNF
would require an extended period of storage. In its most recent estimate, prior to termination of
the Yucca Mountain repository program, DOE projected that, if waste acceptance were to begin in
2020, there would be a need for commercial interim storage until at least 2056, given this
projected shipment rate and the continued generation of new SNF.25
Also, current law—the NWPA—sets a limit on how much waste can be put in the first repository,
and the U.S. inventory of SNF and other high-level waste requiring disposal has already exceeded
this limit. The NWPA “prohibit[s] the emplacement in the first repository of a quantity of spent
fuel containing in excess of 70,000 metric tons of uranium (MTU)26 or a quantity of solidified
high-level radioactive waste resulting from the reprocessing of such a quantity of spent fuel until
such time as a second repository is in operation.”27 Of this 70,000 MTU limit set by Congress on
the first repository in the NWPA, approximately 90% (63,000 MTU) of the capacity is allocated
to commercial spent nuclear fuel and high-level radioactive waste from reprocessing.28 The
remaining 10% capacity would be used for about 2,455 MTU of DOE spent nuclear fuel
(including naval spent nuclear fuel) and the equivalent of 4,667 MTU of DOE high-level
radioactive waste.29 Hence, the current quantity of SNF (i.e., 67,450 MTU of civilian SNF and
2,458 MTU of DOE-owned SNF) and high-level waste being stored would fill the proposed
Yucca Mountain repository beyond the limit imposed by Congress in the NWPA, necessitating a
need to build a second repository or change the legal limit. DOE has evaluated the capacity of the
proposed Yucca Mountain repository and concluded that Yucca Mountain could hold more than
24

See “Hazards and Potential Risks Associated with SNF Storage” below.
Christopher A. Kouts, Principal Deputy Director, Office of Civilian Radioactive Waste Management, U.S.
Department of Energy, “Yucca Mountain Program Status Update,” July 22, 2008, p. 18.
26
Metric tons of uranium (MTU) is a common unit of measurement for SNF, which allows for consistent
measurement/estimation of fuel burnup. In some cases SNF is measured by metric tons of heavy metal or initial heavy
metal (to distinguish the uranium fuel from the metal cladding), which have significant differences for evaluating
reactor operations, but the distinction reflects a relatively minor difference for measurement purposes in this overview
of SNF inventory.
27
42 U.S.C. §10134.(d).
28
Most reprocessing in the United States was performed for separation of nuclear materials for nuclear weapons and
other defense purposes. A relatively small amount of high-level radioactive waste was generated at, and remains stored
at, the West Valley site in New York, after being vitrified in the 1990s. Most of the material reprocessed at the West
Valley site was civilian SNF.
29
U.S. Department of Energy Office of Civilian Radioactive Waste Management, Final Supplemental Environmental
Impact Statement for a Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste
at Yucca Mountain, Nye County, Nevada Summary, DOE/EIS-0250F-S1, June 2008.
25

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the legal limit of 70,000 MTU and “has the physical capability to allow disposal of a much larger
inventory.”30
If waste were accepted at a consolidated nuclear waste storage site, rather than a disposal
repository, the need for interim storage technologies could continue for a longer period. Hence,
the issues related to safe long-term SNF storage—regardless of the current debate about a
permanent geologic repository—warrant consideration. A recent study by the Massachusetts
Institute of Technology (MIT) concluded that “planning for the long term interim storage of spent
nuclear fuel—for about a century—should be part of fuel cycle design.”31 The issues and options
associated with current national policies are discussed below.
The recent change in the Yucca Mountain repository program is not the first time that concern
about the path forward of a permanent geologic repository has caused increased attention to longterm, possibly consolidated, storage of SNF. After the failure of the salt dome waste repository
program near Lyons, KS, the Atomic Energy Commission32 proposed in 1972 a program for longterm (100-year) retrievable surface storage.33 In 1987, the same amendments to the Nuclear Waste
Policy Act (NWPA) that identified the Yucca Mountain site also established the Monitored
Retrievable Storage Commission (ended in 1989) and a position of the “Nuclear Waste
Negotiator,” which was eliminated in 1995 after several years of unsuccessful attempts to find a
voluntary host community for a repository or monitored retrievable storage facility for nuclear
waste.34 During the 1990s, Congress tried, unsuccessfully, to enact legislation to help establish a
temporary consolidated storage site for commercial spent nuclear fuel near the Yucca Mountain
site. A number of analysts35 have found that interim on-site storage or SDNF using dry casks is a
viable option, and some have recommended that interim storage of spent fuel be implemented
deliberately for a period of at least 100 years.36
Second, SNF stored outside of a reactor comprises a source of radioactivity requiring durable
protection. Although radioactive decay reduces the amount of radioactivity in SNF, dropping
sharply soon after discharge from a reactor, SNF provides a significant and long-term
radioactivity source term for risk analyses. While the nuclear fuel in an operating reactor typically
contains a larger amount of radioactivity, in terms of curie content, than stored SNF, much of this
curie content is composed of relatively short-lived fission products, and includes more volatile
constituents, compared to SNF. Although there have been some releases of radioactivity from
stored SNF (see “Hazards and Potential Risks Associated with SNF Storage” below), there is no
evidence of any consequent significant public exposures or health impacts. Nonetheless,
30
DOE, Office of Civilian Radioactive Waste Management, “The Report to the President and the Congress by the
Secretary of Energy on the Need for a Second Repository,” DOE/RW-0595; December 2008.
31
Massachusetts Institute of Technology, The Future of the Nuclear Fuel Cycle: An Interdisciplinary MIT Study, MIT,
Cambridge, MA, 2011, at page xi.
32
The Atomic Energy Commission (AEC) was a predecessor to the U.S. Department of Energy (DOE). The Energy
Research and Development Administration succeeded the AEC in 1975 and was replaced by DOE in 1978.
33
Walker, J. Samuel (NRC Historian), The Road to Yucca Mountain: The Development of Radioactive Waste Policy in
the United States, University of California Press, 2009; and Atomic Energy Commission Press Release, Frank K.
Pittman, “Management of Commercial High-Level Nuclear Radioactive Waste,” July 25, 1972, AEC Press release.
34
42 U.S.C. 10242.
35
See Allison Macfarlane, “Interim Storage of Spent Fuel in the United States,” Annual Review of Energy and the
Environment, vol. 26, 2001.
36
Arjun Makhijani and Scott Saleska, High-Level Dollars, Low-Level Sense, Institute for Energy and Environmental
Research, Apex Publishers, Takoma Park, MD 1991.

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significant concerns have been raised about the potential for releases from stored SNF.37 These
concerns have been heightened in the wake of the incident at the Fukushima Dai-ichi reactors in
Japan, about which there have been conflicting accounts and some uncertainty regarding the
condition of the stored SNF.
Extended storage has also raised concerns about long-term site safety. For example, in the wake
of general concern about the risks from extreme weather and sea level rise from climate change,
as well as specific concerns about SNF stored near flood-prone rivers (e.g., along the Missouri
River), some have expressed urgency about the need to relocate SNF storage.38 NRC, however,
found that sea level rise was not a credible threat to existing and planned on-site nuclear waste
storage for the next several decades: “Based on the models discussed in the [National Academy of
Sciences/National Research Council study], none of the U.S. [Nuclear Power Plants] (operational
or decommissioned) will be under water or threatened by water levels by 2050.”39
Third, the federal government faces a significant and growing liability to pay claims resulting
from its failure to begin accepting waste from commercial utilities under the 1987 NWPA.40 The
U.S. government41 has paid approximately $1 billion42 to pay a series of claims by utilities that
DOE had, at least partially, breached its contracts to accept SNF.43 The federal government has
been paying claims for commercial utility costs for SNF storage since 2000.44 These claims arise
from the 76 standard contracts DOE signed in 1983, largely with commercial utilities, of which
74 have filed claims against DOE for damages arising from failure to accept the SNF by 1998.45
37
Several states, including New York and Connecticut, have challenged NRC’s “Waste Confidence” rule, which
concluded that SNF “can be stored safely and without significant environmental impacts …” (See United States Court
of Appeals for the District of Columbia Circuit, State of New York, et al., Petitioners, Nos. 11-1045, 11-1051, -against11-1056, 11-1057 Nuclear Regulatory Commission and United States of America, Respondents); and Alvarez, Robert,
Spent Nuclear Fuel Pools in the U.S.: Reducing the Deadly Risks of Storage, Institute for Policy Studies, May 2011;
Zhang, Hui. Radiological Terrorism: Sabotage of Spent Fuel Pools, INESAP: International Network of Engineers and
Scientists Against Proliferation no. 22 (December 2003): 75-78.
38
A. G. Sulzberger and Matthew L. Wald, “Flooding Brings Worries Over Two Nuclear Plants,” New York Times, June
20, 2011.
39
U.S. Nuclear Regulatory Commission, “Consideration of Environmental Impacts of Temporary Storage of Spent
Fuel After Cessation of Reactor Operations; Waste Confidence Decision Update; Final Rule,” 75 Federal Register
81032, December 23, 2010; and National Academies/National Research Council, Committee on Climate Change and
U.S. Transportation, Potential Impact of Climate Change on U.S. Transportation: Special Report 290, 2008.
40
For more information on this liability issue, see CRS Report R40996, Contract Liability Arising from the Nuclear
Waste Policy Act (NWPA) of 1982, by (name redacted).
41
The claims have been paid from the “Judgment Fund,” which is a permanent, indefinite appropriation for the
payment of judgments against the United States managed by the U.S. Department of Justice (see 31 U.S.C. §1304), not
from appropriations to DOE through the Energy and Water Development Subcommittees. The U.S. government cannot
use the Nuclear Waste Fund to pay for any of the damages that the utilities incur as a result of DOE’s delay, because
on-site storage is not one of the uses of the NWF authorized by the NWPA (see Alabama Power Co. v. United States
Department of Energy, 307 F.3d 1300 (11th Cir. 2002)).
42
U.S. Government Accountability Office, GAO-11-731T, Nuclear Waste, Disposal Challenges and Lessons Learned
from Yucca Mountain, June 1, 2011, http://www.gao.gov/new.items/d11731t.pdf.
43
The utilities’ damages claims largely consist of the costs incurred to store SNF. The costs include capital costs to
construct dry storage facilities or additional wet storage racks, costs to purchase and load casks and canisters, and costs
of utility personnel necessary to design, license, and maintain these storage facilities.
44
Court of Appeals for the Federal Circuit, in Maine Yankee Atomic Power Co. v. United States, 225 F.3d 1336, 1343
(Fed. Cir. 2000). and Pac. Gas & Elec. Co. v. United States, 536 F. 3d 1282, 1284, 1287 (Fed. Cir. 2008.)
45
Michael F. Hertz, U.S. Department of Justice, Statement Before the Blue Ribbon Commission on America’s Nuclear
Future, February 2, 2011.

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The future estimated costs for storage of commercial SNF are approximately $500 million
per year.46
Fourth, some have argued that the uncertainty and concerns about nuclear waste management
have contributed to the lack of investment in new nuclear power plants, resulting in a failure of
the industry to expand, along with relatively high capital costs.47 An American Physical Society
Panel chaired by a former NRC chairman, and including another former NRC chairman and a
former Under Secretary of Energy, concluded, in part, “there is a concern that the buildup of spent
fuel at reactor sites and lack of progress on final disposition could be serious constraints on the
growth of the domestic nuclear power industry by discouraging investment in new nuclear power
plants and enhancing the difficulty of siting new nuclear power plants.”48
A recent article by long-time nuclear waste observers and former officials argued that “solid
public acceptance of nuclear energy ... may well turn on a credible promise of a geologic
repository becoming available within the next few decades.”49 Another longtime observer of the
nuclear industry indicated, “[e]ven if the public were otherwise prepared to go along with a major
expansion of nuclear power, much less reprocessing, it is unlikely to do so without a new,
credible regime for disposing of our existing and future nuclear power wastes.”50
The recent report by the BRC also implicated the current “impasse” in the U.S. nuclear waste
program as a hindrance to expansion of nuclear power, among other impacts:
Put simply, this nation’s failure to come to grips with the nuclear waste issue has already
proved damaging and costly and it will be more damaging and more costly the longer it
continues: damaging to prospects for maintaining a potentially important energy supply
option for the future, damaging to state-federal relations and public confidence in the federal
government’s competence, and damaging to America’s standing in the world—not only as
a source of nuclear technology and policy expertise but as a leader on global issues of
nuclear safety, non-proliferation, and security.51

States have imposed their own controls on SNF management and related nuclear power plant
operations.52 Specifically, some state laws prohibit construction of any new nuclear power plants
until the current backlog of spent fuel is addressed. According to the National Conference of State
Legislatures, “Thirteen states have laws prohibiting energy utilities from even considering adding
46
American Physical Society Nuclear Energy Study Group, Consolidated Interim Storage of Commercial Spent
Nuclear Fuel: A Technical and Programmatic Assessment, February 2007; Michael F. Hertz, Deputy Assistant
Attorney General, Civil Division, Before the Committee on the Budget, U.S. House of Representatives, Budgeting for
Nuclear Waste Management, presented on July 16, 2009; and Hertz, Michael F., U.S. Department of Justice, Statement
Before the Blue Ribbon Commission on America’s Nuclear Future, February 2, 2011.
47
Frank von Hippel, The Uncertain Future of Nuclear Energy, International Panel on Fissile Materials Report #9,
September 2010.
48
American Physical Society Nuclear Energy Study Group, Consolidated Interim Storage of Commercial Spent
Nuclear Fuel: A Technical and Programmatic Assessment, February 2007.
49
Luther J. Carter, Lake H. Barrett, and Kenneth C. Rogers, “Nuclear Waste Disposal Showdown at Yucca Mountain,”
Issues in Science and Technology (Lawrence Livermore National Laboratory), Fall 2010.
50
Richard B. Stewart and Jane B. Stewart, Fuel Cycle to Nowhere: U.S. Law and Policy on Nuclear Waste (Nashville,
TN: Vanderbilt University Press, 2011).
51
Blue Ribbon Commission on America’s Nuclear Future, Report to the Secretary of Energy, January 26, 2012, p. vi.
52
Richard C. Moore, Enhancing the Role of State and Local Governments in America’s Nuclear Future: An Idea
Whose Time Has Come, prepared for the Blue Ribbon Commission on America’s Nuclear Future, May 2011.

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new nuclear reactors until the waste problem has been solved.”53 State authority, however, is
limited under the Atomic Energy Act.54
This report cannot resolve these issues, but it does provide some vital background to help support
an informed debate on the issues of SNF storage.

What Is Spent (Used) Fuel?
In many cases, discussions of “nuclear waste”55 are, in fact, referring to SNF. The “fuel” in
commercial nuclear fuel is uranium oxide56 formed into solid cylindrical ceramic pellets,
contained in zirconium alloy tubes supported in a rigid metal framework, or “assembly” (see
Figure 1). These fuel assemblies are composed of individual rods of approximately half an inch
in diameter and 12 to 15 feet long, with each assembly approximately 5 inches to 9 inches on a
side.57 The fuel assemblies for a boiling water reactor (BWR) are about half the mass (about 0.18
MTU/assembly) of a typical pressurized water reactor (PWR), which are about 0.44
MTU/assembly.58 The difference in design of BWR and PWR reactors is significant in how SNF
is stored, which is discussed below. Both types of reactors are “light water reactors” because they
use ordinary (“light”) water for cooling and reducing neutron energy.59 All current U.S.
commercial reactors are light water reactors.

53

Savage, Melissa, “The Other Nuclear Problem,” State Legislatures Magazine (National Conference of State
Legislatures), May 2011 (see http://www.ncsl.org/?tabid=22533). Also, see CRS Report R41984, State Authority to
Regulate Nuclear Power: Federal Preemption Under the Atomic Energy Act (AEA), by (name redacted).
54
See CRS Report R41984, State Authority to Regulate Nuclear Power: Federal Preemption Under the Atomic Energy
Act (AEA), by (name redacted).
55
See CRS Report RL32163, Radioactive Waste Streams: Waste Classification for Disposal, by (name redacted)
(2006), and out of print CRS Report RS22001, Spent Nuclear Fuel Storage Locations and Inventory, by (name re
dacted) (2004; available upon request).
56
Uranium dioxide (UO2) is the most commonly used form of uranium used for fuel in commercial nuclear reactors,
which is the focus of this report. Commercial reactor fuel uses uranium enriched to approximately 3%-5% U-235, with
the balance of the uranium (approximately 95%-97%) U-238, which is “non-fissile,” or incapable of sustaining a
nuclear chain reaction. Other reactors for use in naval nuclear propulsion reactors, nuclear materials production
reactors, and research applications may have different compositions in terms of uranium enrichment, overall structure,
and cladding, but this report focuses on the typical fuel used in most commercial reactors. Some have proposed using
thorium and/or metallic fuels (see, e.g., http://www.ltbridge.com) for “next generation” nuclear fuels.
57
W. J. Bailey, A.B. Johnson, and D.E. Blahnik et al., Surveillance of LWR Spent Fuel in Wet Storage, Battelle Pacific
Northwest Laboratories, Electric Power Research Institute Report NP-3765, October 1984.
58
The mass per assembly is based on the average total discharge mass (metric tons of heavy metal, or MTHM) reported
by the Energy Information Administration (EIA) for BWR and PWR reactors from 1968 to 1998, which was a period
for which complete and comparable records were available at Energy Information Administration, Form RW-859,
“Nuclear Fuel Data” (1998). The quantity of spent fuel is measured in MTHM. Heavy metal refers to elements with
atomic number greater than 89—in SNF, almost all heavy metal is uranium. The mass generally refers to the initial
heavy metal (i.e., before irradiation), and is roughly equivalent to the MTU. After discharge, some (about 4%) of the
uranium has been replaced by fission products.
59
Light water reactors are distinguished from heavy water reactors, which use deuterium oxide (D20) instead of H20.
Like H20, D2O is composed of two hydrogen atoms and an oxygen atom, except the hydrogen atoms each possess an
extra neutron.

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Figure 1. Nuclear Fuel Assembly

Source: CRS-produced graphic using SNF assembly image from General Electric Company.
Note: Illustrates a typical light water reactor nuclear fuel assembly used in U.S. commercial nuclear power
reactors, and may not resemble fuel for research reactors, naval nuclear propulsion reactors, or nuclear power
reactor fuel in other countries.

The production of electricity through nuclear fission in a light water reactor uses low-enriched
uranium (3%-5% U-235) pellets that undergo a nuclear fission process inside the reactor. The
fission process heats water to generate steam that turns the turbine generator, thereby generating
electricity. In general, the fuel rods are productive for approximately 54 months. Roughly every
18 months, utilities generally conduct a refueling outage in which approximately one-third of the
fuel assemblies are replaced with new assemblies. A replaced fuel assembly becomes spent (or
“used”) nuclear fuel when it has been irradiated and removed from a nuclear reactor after it is no
longer cost-effective to generate power. This reduced power output is caused by the accumulation
of radionuclides generated by the fission (splitting) of the uranium atoms and the relative
reduction in fissile isotopes.60 These fission products effectively “poison” the nuclear chain
reaction by interfering with the otherwise self-sustaining fission process. The SNF assemblies
must be removed to maintain the necessary power production level to generate electricity. A
typical commercial nuclear power plant fuel rod assembly operates in a reactor for approximately
4½ years before being removed for storage and eventual disposal.61 Once removed from the
60
The relatively large uranium-235 atom splits into smaller fission products, with different radiological and chemical
characteristics, such as cesium-137 (half-life (t1/2) = 30 years), strontium-90 (t1/2 = 29 years), and technecium-99 (t1/2
= 211,000 years). It is one of the fundamentally unique and remarkable characteristics of nuclear fission that it is
capable of creating wholly new elements from others in a process that had previously eluded humans for centuries,
since the days of the ancient alchemists.
61
Some have suggested that “reprocessing” (dissolving of solid spent fuel rods in acid and using organic solvents to
separate long-lived plutonium and uranium isotopes from certain fission products) could provide an alternative to spent
fuel disposal. In the United States, most reprocessing was conducted from the 1940s until 1992 to extract plutonium
(continued...)

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reactor core, SNF continues to generate heat and radiation, and, although is rapidly attenuated,
requires careful management for thousands of years. Commercial reactors in the United States
generate about 2,000 MT of SNF annually.62
The variety of SNF types is as diverse as the range of reactors and their functions, which is
dominated by, but not limited to, commercial nuclear power plants designed to produce electric
power. This report is focused on commercial SNF, in contrast to smaller quantities of other types
of SNF, which include SNF with different designs and characteristics from other sources:
•

DOE production reactors used for producing nuclear materials, such as Pu-239
(weapons-grade plutonium) and Pu-238 (for deep space missions and other
applications requiring durable power sources);63

•

reactors used for research, analysis of materials, basic science experiments, and
training;64 and

•

naval propulsion reactors used for submarines and aircraft carriers.65 The Naval
Nuclear Propulsion Program (i.e., nuclear submarines, aircraft carriers, and Navy
prototype and training reactors) has generated about 27 MTU of SNF, which is
stored at the Idaho National Laboratory.66

(...continued)
and other nuclear materials, primarily for nuclear weapons production. A complete examination of this technology is
beyond the scope of this report and has been addressed in other CRS products. See, e.g., CRS Report RL34234,
Managing the Nuclear Fuel Cycle: Policy Implications of Expanding Global Access to Nuclear Power, coordinated by
Mary Beth Nikitin.
62
The January 2011 NEI “Used Fuel” inventory report by Brian Gunterman estimated the average annual discharges of
commercial SNF in the United States are slightly more than 2,000 MTHM (2,248 MTHM average annual rate for 20052010, and 2,259 MTHM average annual discharge rate projected for 2005-2025), but 2,000 MTHM is the estimated
annual rate most commonly used in other analyses and is used here to provide comparability.
63
The production reactors were all built by the former Atomic Energy Commission and the original Manhattan Project
in World War II at the Hanford Site in eastern Washington and the Savannah River Plant in South Carolina. Instead of
generating heat to drive a turbine to generate electricity, these reactors generally used high-enriched uranium fuel to
irradiate targets to transmute U-238 into weapons-grade Pu-239. Although commercial reactors also produce Pu-239,
theft of commercial SNF is not directly a significant proliferation risk because the concentration of Pu-239 is relatively
low (compared to other plutonium isotopes). Perhaps more significantly, extracting the most useful plutonium isotope
for efficient weapons (i.e., Pu-239) requires a much more challenging step of reprocessing to separate the Pu-239 from
the fission products, which otherwise renders the fissile material useless for power or weapons, thereby making
commercial SNF a low proliferation risk. Another difference with DOE production reactor SNF, compared to
commercial SNF, is that the fuel cladding is relatively thin-walled to facilitate reprocessing by reducing the material
that has to be dissolved. One reactor (“N-reactor” at the Hanford site) was built to produce both weapons material and
electricity. Although it was built in the early 1960s as a potential model for other “dual use” reactors, it was never
replicated and shut down in the 1980s.
64
Research reactor fuel is generally smaller than commercial fuel (i.e., about 4 feet compared to 12 to 15 feet long). In
many cases, research reactors used high-enriched or “weapons grade” uranium and posed a greater proliferation threat
than low-enriched commercial fuel. DOE has operated a Reduced Enrichment Research and Test Reactor Program to
help these reactors convert to high-density, low-enriched uranium fuel.
65
The fuel used by the Naval Nuclear Propulsion Program has a significantly different and classified design from
commercial, production, or research reactor fuel. Among other things, it uses high-enriched uranium and lasts
considerably longer.
66
Blue Ribbon Commission paper by DOE contractors, “Used Fuel Disposition: U.S. Radioactive Waste Inventory and
Characteristics Related to Potential Future Nuclear Energy Systems,” FCRD-USED-2011-000068, Rev. 18, May 2011.

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Virtually all of this SNF is DOE-owned and comprises less than 4% of the amount of commercial
SNF stored in the United States (2,458 MTU vs. 67,450 MTU). These noncommercial SNF types
include a wide range of designs and sizes, which differ significantly from commercial reactor
fuel, but share the same basic radioactivity hazard and need for long-term isolation. Many of the
technical issues associated with long-term storage of commercial SNF also apply to these fuel
types. This inventory of DOE-owned SNF does not include the millions of gallons of liquid highlevel waste stored in underground tanks or the canisters of vitrified high-level waste resulting
from reprocessing SNF at DOE sites.

How Is Spent Fuel Stored Now?
There are essentially two modes of SNF storage in the United States: wet pools and dry casks.67
Wet storage pools are the most common method for storing SNF in the United States, accounting
for about 73% (49,338 MTU) of the current commercial SNF inventory. The remaining 27%
(18,112 MTU) of commercial SNF is stored in dry casks on concrete pads or horizontal bunkers.
Operating commercial nuclear power plants must store SNF at least a year (often five years or
more) in “spent fuel pools” to allow for some initial cooling after discharge from the reactor.
Because of limited wet storage capacity for SNF, most sites employ a combination of wet pool
and dry cask storage. NRC regulates both wet fuel pools68 and dry cask installations69 and regards
both as adequately protective (see “Options for Storing Spent Nuclear Fuel” below).
Wet storage pools are constructed of reinforced concrete walls several feet thick, with stainless
steel liners. The water is typically about 40 feet deep, and serves both to shield workers from
radiation and cool the SNF assemblies. Storage pools vary somewhat in size, but are generally
large enough to store fuel rods vertically, with ample depth to provide space above the SNF
storage racks for unloading and loading SNF transfer casks with SNF that is approximately 12 to
15 feet long. The cooling water chemistry is generally carefully controlled to minimize corrosion.
Just as the fuel assemblies’ designs differ among different reactor types, described above, the
designs of the pool storage basins differ significantly among different reactor designs, often
unique to each plant. Currently, commercial nuclear reactors in the United States are light water
reactors, of which there are two basic designs: boiling water reactors (BWRs; see Figure 2), and
pressurized water reactors (PWRs; see Figure 3), the former being the type of reactor built at the
Fukushima Dai-ichi site in Japan. Some SNF being stored in the United States, however, was

67
Dry cask storage is sometimes considered synonymous with “Independent Spent Fuel Storage Installation” (ISFSI)
because all but one ISFSI site (GE Morris in Illinois) uses dry casks. This report uses both terms where appropriate.
Also, this report generally refers to typical commercial dry cask storage. In fact, a wide range of dry storage
configurations are used, including vertical and horizontal configurations (see Figure 4), as well as in-ground and
indoor vaults, which are used disproportionately at DOE sites.
68
10 C.F.R. Part 50.
69
10 C.F.R. Part 72.

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generated by other reactor types70 not currently used in this country, such as high temperature
gas-cooled reactors and liquid sodium reactors.71
The design of storage pools has been highlighted recently for the GE Mark I BWR, which has
been used at dozens of nuclear power plants worldwide, including the Fukushima Dai-ichi plant,
as well as 20 reactors operating in the United States. The SNF storage pool for the GE Mark I
reactor is approximately 35 feet wide, 40 feet long, and 39 feet deep (10.7 meters wide, 12.2
meters long, and 11.9 meters deep), with a water capacity of almost 400,000 gallons (1.51 million
liters). Another feature of the GE Mark I BWR is that the SNF storage pool is located inside the
same secondary containment structure as the reactor and many critical control systems. Finally,
the SNF storage pools in the BWR Mark I reactors are located several stories above ground level.
The potential safety considerations of these design features are discussed below in “Hazards and
Potential Risks Associated with SNF Storage.”
Figure 2. SNF Storage Pool Location in Boiling Water Reactor

Source: GE-Hitachi Nuclear Energy.
Note: Illustrates a GE Mark I BWR design, which is one of a number of BWR designs.
70
Other, generally noncommercial, reactors types have been used for nuclear materials production by the Department
of Energy and predecessor agencies for nuclear weapons material production, and for research purposes. In addition,
commercial reactors in the former Soviet Union have used other designs, such as the graphite reactor (known as a
“RBMK” reactor) used at the Chernobyl plant in the Ukraine.
71
The Fort St. Vrain facility in Colorado (25 MT and 2,208 assemblies of SNF stored on-site, while the balance was
shipped off-site to DOE’s Idaho National Engineering Laboratory) was a high temperature gas-cooled reactor. The
Santa Susanna Field Laboratory in California and the Fermi 1 reactor in Michigan were liquid sodium reactors. In
addition to this historic variation in reactor designs in the United States, reactor and fuel designs in other countries vary
significantly. Canada, for example, has used “CANDU” reactors that use heavy water, and the British have used
“Magnox” reactors, with relatively unstable fuel intended for relatively quick reprocessing.

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Figure 3. PWR SNF Storage Pool Location

Source: Timothy Guzda, Union of Concerned Scientists, modified by CRS.

The SNF storage capacities using wet storage pools at U.S. commercial power reactors generally
range from approximately 2,000 assemblies to 5,000 assemblies (averaging approximately 3,000
SNF fuel assemblies). Typically, U.S. spent fuel pools are filled with spent fuel assemblies up to
approximately three-quarters of their capacity to allow space for at least one full reactor core load
of fuel to be stored as needed. In contrast, the wet storage pool building located nearby but
separate from the reactors at the Fukushima Dai-ichi site contains about 6,000 spent fuel
assemblies, which was about half of the SNF at the site. U.S. reactor facilities do not typically
have an additional spent fuel wet storage building for on-site SNF consolidation like that at
Fukushima Dai-ichi.72
A critical feature of wet pools is the need for power to provide makeup water and circulate the
water to keep it from boiling off and uncovering the fuel, especially for recently discharged SNF
that is still thermally and radioactively hot. The SNF loses much of its heat in the first few weeks
after discharge, and after five years produces relatively little thermal energy. Nonetheless, without
circulation pumps helping remove the accumulated heat, the heat emitted from SNF can be
sufficient to boil away the cooling water.
72
The NRC Near-Term Task Force report in July 2011 put the number of assemblies in this basin at 6,291, while the
INPO report from November 2011 indicated 6,375 assemblies were located in this separate storage pool. See U.S.
NRC, Recommendations for Enhancing Reactor Safety in the 21st Century: The Near-Term Task Force Review of
Insights from the Fukushima Dai-ichi Accident, July 12, 2011 (http://pbadupws.nrc.gov/docs/ML1118/
ML111861807.pdf); and Institute for Nuclear Power Operations, Special Report on the Nuclear Accident at the
Fukushima Daiichi Nuclear Power Station, INPO 11-005, Rev. 0, November 2011, at page 35 (http://www.nei.org/
resourcesandstats/documentlibrary/safetyandsecurity/reports/special-report-on-the-nuclear-accident-at-the-fukushimadaiichi-nuclear-power-station).

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Dry casks are typically constructed in a cylindrical shape with an inner steel canister directly
storing the SNF assemblies that is bolted or welded closed, in an outer concrete cask (see Figure
4). After loading with SNF, dry casks are stored outside73 vertically on a purpose-built concrete
pad, or horizontally in a concrete storage bunker. An individual SNF storage cask can weigh more
than 100 MT (220,000 pounds) and be more than 15 feet long and 6 feet outside diameter.74 One
regularly used SNF storage container (the “NUHOMS 61BT”) weighs 22 tons empty and 44 tons
loaded with SNF.75 The largest dry casks licensed for use in the United States can hold up to 40
PWR spent fuel assemblies or 68 BWR spent fuel assemblies. The Transportation, Aging, and
Disposal (TAD) Canister System proposed by DOE can hold up to 21 PWR or 44 BWR spent
fuel assemblies.76 The storage capacity of a dry cask depends not only on size but also on the
burn-up and age of the SNF fuel to be stored. There are more than 50 different types of dry casks
produced by about a dozen manufacturers approved by NRC for general use in the United
States.77 NRC regulates dry cask storage systems at 10 C.F.R. 72, and with various guidance
documents (e.g., NUREG-1536).
The key feature of dry storage units is that, once constructed, filled, and sealed, they require no
power for circulation of cooling water and are generally regarded as “passively safe.” Natural
convection of air through the outer concrete shell of the storage system is sufficient to cool the
steel containment canister inside without reliance on power for pumps or fans. By contrast, a wet
storage pool system typically requires power for recirculation and/or makeup of cooling water.
Loss of power for a wet pool storage system for more than a few days or weeks could cause water
levels to drop to levels resulting in potential risks (e.g., inadequate shielding or exposure of
SNF).78 The robustness of dry cask storage was illustrated recently by the results of an August
2011 earthquake centered in Mineral, VA, near the North Anna nuclear power plant.79 According
to NRC, the earthquake caused movement of the SNF dry storage casks, weighing more than 100
tons, of approximately 1 to 4½ inches, and had no significant impact on the casks or the SNF.

73
In contrast to the practice of storing SNF in dry casks on outdoor storage pads in the United States, Germany requires
dry casks to be stored in hardened storage buildings. See Ulrich Alter (Federal Ministry for the Environment and
Nuclear Safety), Management of Radioactive Waste and Spent Fuel in Germany, presentation to the IAEA Conference,
May 31, 2010.
74
IAEA, “Operation and Maintenance of Spent Fuel Storage and Transportation Casks/Containers,” IAEA-TECDOC1532, January 2007.
75
See http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/37/088/37088622.pdf.
76
See “Safety & Security of Commercial Spent Nuclear Fuel Storage: Public Report,” National Academies Press,
Washington, DC (2006).
77
See http://www.nrc.gov/waste/spent-fuel-storage/designs.html.
78
For example, the common SNF storage pool at the Fukushima site, in which about 60% of the SNF at the site was
stored, was estimated to be capable of losing power for at least 30 days before it caused a concern. See Institute for
Nuclear Power Operations, Special Report on the Nuclear Accident at the Fukushima Daiichi Nuclear Power Station,
INPO 11-005, Rev. 0, November 2011, at page 35 (http://www.nei.org/resourcesandstats/documentlibrary/
safetyandsecurity/reports/special-report-on-the-nuclear-accident-at-the-fukushima-daiichi-nuclear-power-station.)
79
See generally http://www.nrc.gov/info-finder/reactor/na1.html.

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Figure 4. Example of Dry Cask Storage

Source: U.S. Nuclear Regulatory Commission.
Note: This figure illustrates a free-standing upright design. Other dry cask designs include horizontal and inground vaults.

International Nuclear Waste Convention
NRC issues both general licenses and sitespecific licenses for dry storage facilities.82 A
The United States is a party80 to the Joint Convention on
the Safety of Spent Fuel Management and on the Safety of
general license allows licensees to avoid
Radioactive Waste Management.81 The waste treaty
repeating certain evaluations (e.g., National
includes provisions covering transboundary waste
Environmental Policy Act or seismic review),
shipments, and facility planning, operations and closure,
if they have already been conducted pursuant
as well as requiring annual reports by each “Contracting
to the plant operating licensing process. Part
Party.” This treaty does not create any new obligations
on U.S. SNF management, and provides a framework for
72 contains NRC’s regulations for the dry
a variety of strategies employed by a number of
storage of power reactor spent fuel on or off a
countries.
reactor site and for pool storage away from a
reactor site. The NRC regulations have been
adopted consistent with the International Convention on Nuclear Waste (see inset box).
The first commercial dry SNF storage system in the United States was established at the North
Anna nuclear power plant site in Virginia in 1986, and employs both vertical casks and horizontal
modules.83 Since then, an increasing number of storage locations have employed dry casks at an
80

The United States signed the treaty on September 29, 1997, and ratified it on April 15, 2003. See
http://www.iaea.org/Publications/Documents/Conventions/jointconv_status.pdf.
81
International Atomic Energy Agency, Joint Convention on the Safety of Spent Fuel Management and on the Safety of
Radioactive Waste Management, INFCIRC/546, December 24, 1997. See http://www.iaea.org/Publications/
Documents/Infcircs/1997/infcirc546.pdf.
82
10 C.F.R. 72.2 and see U.S. NRC, “NRC Standard Review Plan for Dry Cask Storage Systems” (NUREG-1536).
83
Two types of dry storage are used at the site: 27 vertical Areva/Transnuclear (TN)-32 metal casks and 26 TN
NUHOMS HD-32PTH horizontal storage modules. See http://www.nrc.gov/about-nrc/emerg-preparedness/virginiaquake-info/north-anna-isfsi-summary.pdf; and Kenneth D. Kok, Nuclear Engineering Handbook, CRC press, 2009.

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increasingly rapid rate. The amount of SNF transferred to dry cask storage in 2010 (8,606
assemblies) was nearly four times the average amount transferred since the use of dry cask
storage began in 1986 (2,309 assemblies/year),84 and was more than 50% greater than the
assemblies transferred to dry casks in 2009.85 The amount of SNF stored in wet pools compared
to dry systems dropped from 91% (44,712 MTU/49,401 MTU) in 2002 to 73% (49,338
MTU/67,450 MTU) in 2011.
The amount of SNF stored in wet pools increased by about 10%, from 44,712 MTU in 2002 to
49,338 in December 2011, at an average annual rate of 437 MTU/year (1% average annual
increase). The amount of SNF stored in dry systems increased during the same period by 286%,
from 4,689 MTU to 18,112 MTU. The rate change in the amount of stored SNF reflected an
average annual increase of total stored SNF of 1,579 MTU/year (3.2% average annual increase)
and average increase in dry system storage of 1,124 MTU/year (24%/year average annual
increase)—that is, storage of SNF in dry systems increased, on average, 24 times faster than
storage in wet pools.
Regardless of government policies and requirements about SNF storage, it is likely that the trend
toward more dry cask storage will continue because of the need for storage and the changing
economic value, and extended pay-off period, of these investments given the long-term
uncertainty about SNF disposal.

Where Is Spent Nuclear Fuel Located Now in the
United States?
Spent nuclear fuel is stored at 77 different sites86 in the United States, including 63 sites with
licensed operating commercial nuclear power reactors, 4 DOE-operated sites, 9 former operating
nuclear reactor sites, and the Morris, IL, proposed reprocessing plant. Generally, the storage sites
include facilities at the 104 licensed operating nuclear power reactor locations where it was
generated (see Table 1 and Figure 5), as well as 10 “stranded” commercial sites where no
reactors operate (including the Morris, IL), and 4 DOE-operated facilities. In fact, virtually every
site that has ever hosted a commercial nuclear reactor is currently also a storage site for SNF. As
discussed above, because of practical, technical, and logistical limitations and other issues, SNF
is likely to stay at existing sites for a significant period, regardless of decisions on a permanent
84
Gutherman Technical Services (hereinafter referred to as the NEI Report), “2010 Used Fuel Data,” Report to Nuclear
Energy Institute (Marcus Nichol), January 18, 2010.
85
ACI Nuclear Solutions (Brian Gutherman), Report to Nuclear Energy Institute (Everett Redmond), 2009 Used Fuel
Data, January 22, 2010.
86
The term “sites” is used here to refer to geographically distinct locations. This accounting excludes the four sites
where DOE is responsible for SNF storage in Colorado, Idaho, South Carolina, and Washington. Also, Hope Creek and
Salem 1&2 (New Jersey) are counted as a single site because they are adjacent, located on the same artificial island in
the Delaware River, share the same owner (PSEG Nuclear and Exelon), and share a dry cask storage pad using the
same dry cask technology (Holtec Hi-Storm). An SNF storage “facility” is generally associated with a reactor that
produced the SNF (see Figure 2 and Figure 3), except in the case of the Morris, IL, facility, which was initially built
not as a power reactor, but as part of an SNF reprocessing facility that never operated. In many cases there are more
than one nuclear power reactor and SNF storage facility at a “site,” which is a geographically contiguous area. Because
dry cask storage areas are typically independent of a reactor facility at a site, and have a licensing process separate from
the reactor licensing, dry cask storage is generally quantified according to number of sites, not facilities.

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geologic repository. NRC has proposed plans that would consider SNF storage for up to 300
years, in the case of the oldest SNF now in storage.87
Of the 67,450 MTU88 of commercial SNF stored in the United States, approximately threequarters of it (49,338 MTU) is being stored in wet pools at the reactor sites. Of the 74 different
sites89 (some with multiple storage facilities) where commercial spent fuel is stored in the United
States, 55 locations employ dry cask storage for at least part of the storage for commercial SNF.90
There are 27 sites with 36 wet pool storage “facilities” (i.e., in some cases there are multiple wet
pool storage “facilities” co-located at individual sites) where wet pool storage is the only
technology being used at the site.91

87
U.S. NRC, Draft Report for Comment: Background and Preliminary Assumptions For an Environmental Impact
Statement—Long-Term Waste Confidence Update, December 2011, pp. 6-8 and 14.
88
Excludes commercial SNF stored at DOE facilities.
89
Includes the Hitachi-GE site in Morris, IL, but excludes the four DOE-operated sites.
90
This number excludes three sites (Savannah River Site (SC) and Hanford (WA) and Fort St. Vrain (CO)) where
DOE-owned SNF is stored in dry storage facilities. The Idaho National Laboratory (INL) DOE site is included because
some of the SNF stored there is from the Three Mile Island reactor, and the dry storage facility at INL for the TMI SNF
debris is NRC-licensed.
91
Although the NEI data indicate it lacks a dry cask storage facility, the Salem (NJ) site is not included separately in
this accounting because it is adjacent to the Hope Creek site and shares the dry cask storage facility there. Also, the
Morris Site (IL) is included here because it is a wet storage site. In some databases, Morris is mistaken for dry casks
because it is classified as an “Independent Spent Fuel Storage Installation (ISFSI),” which involves dry cask storage at
all of the other ISFSI sites.

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Table 1. U.S. Spent Nuclear Fuel Storage Inventories by State (Ranked by Total SNF Mass)
As of December 31, 2011 (see Table A-1 for data sorted by states alphabetically)
Mass (metric tons of uranium)

Assemblies

Number of
Facilities

Number of
Sites

“Stranded”
SNF
Storage
Sitesb

Illinois

15

8

2

6,900

1,791

8,691

28,242

9,625

37,867

b&c

Pennsylvania

9

5

—

4,606

1,459

6,065

20,898

8,424

29,322

d

South Carolina

8

5

1

2,236

1,808

4,044

5,001

3,896

8,897

b&e

New York

7

4

—

3,082

495

3,577

12,466

1,820

14,286

b&f

North Carolina

5

3

—

3,018

544

3,562

10,612

1,480

12,092

Alabama

5

2

—

2,647

540

3,187

10,978

2,180

13,158

Florida

5

3

—

2,511

445

2,956

5,859

1,024

6,883

f

California

7

4

2

2,017

916

2,933

4,750

2,486

7,236

b&g

Georgia

4

2

—

2,018

592

2,610

7,366

3,264

10,630

Michigan

5

4

1

2,058

502

2,560

6,495

1,537

8,032

b&f

New Jersey

4

2

—

2,025

529

2,554

7,489

2,535

10,024

h

Virginia

4

2

—

970

1,477

2,447

2,120

3,229

5,349

f

Texas

4

2

—

2,121

0

2,121

4,522

—

4,522

Connecticut

4

2

1

1,439

613

2,052

5,050

1,467

6,517

Arizona

3

1

—

1,052

903

1,955

2,490

2,136

4,626

Tennessee

3

2

—

1,095

470

1,565

2,386

1,024

3,410

Maryland

2

1

—

531

808

1,339

1,197

1,824

3,021

f

Wisconsin

4

3

1

915

419

1,334

2,603

1,088

3,691

b&f

Arkansas

2

1

—

607

726

1,333

1,336

1,600

2,936

Louisiana

2

2

—

1,014

235

1,249

3,861

1,148

5,009

Minnesota

3

2

—

678

525

1,203

2,645

1,770

4,415

Ohio

2

2

—

1,083

34

1,117

4,542

72

4,614

State
(15 states
have no
stored SNF)a

CRS-19

Wet
Storage

Dry Cask

Total SNF

Wet
Storage

Dry Cask

Total SNF

Table
Notes

b&g

g

State
(15 states
have no
stored SNF)a

Mass (metric tons of uranium)

Assemblies

Number of
Facilities

Number of
Sites

“Stranded”
SNF
Storage
Sitesb

Nebraska

2

2

—

650

203

853

2,825

808

3,633

Mississippi

1

1

—

602

203

805

3,428

1,156

4,584

Missouri

1

1

—

679

0

679

1,696

—

1,696

Massachusetts

2

2

1

542

122

664

3,082

533

3,615

b

Washington

2

2

1

319

339

658

1,715

1,836

3,551

b

Kansas

1

1

—

646

0

646

1,434

—

1,434

Vermont

1

1

—

513

111

624

2,815

612

3,427

New
Hampshire

1

1

—

455

93

548

944

192

1,136

Maine

1

1

1

0

542

542

—

1,438

1,438

Iowa

1

1

—

259

217

476

1,452

1,220

2,672

Oregon

1

1

1

0

345

345

—

801

801

b

Idaho

1

1

1

50

81

131

144

177

321

b

Colorado

1

1

1

0

15

15

—

2,208

2,208

b&f

U.S. Total
Commercial
Site Storage

119

74

10

46,733

15,859

62,592

165,583

56,493

222,076

U.S. Total
DOE Site
Storage

4

4

4

2,605

2,243

4,848

6,860

8,117

14,977

Wet
Storage

Dry Cask

Total SNF

Wet
Storage

Dry Cask

Total SNF

Table
Notes
g

b

Source: The primary source for these data is the Nuclear Energy Institute (NEI) report, “2011 Used Fuel Data,” prepared by Gutherman Technical Associates, January 14,
2012. Site-specific data on sites with no operating reactors (“Storage-only Sites”) is derived largely from DOE, Report to Congress on the Demonstration of the Interim Storage
of Spent Nuclear Fuel from Decommissioned Nuclear Power Reactor Sites, DOE/RW-0596, December 2008. Data for DOE sites were generally from Frank Marcinowski,
Overview of DOE’s Spent Nuclear Fuel & High Level Waste; Presentation to the Blue Ribbon Commission on America’s Nuclear Future, U.S. DOE, March 25, 2010.
a.

There are currently 15 states with no commercial SNF storage (there may be temporary and relatively small-scale storage of SNF from non-power generating research
and academic reactors): Alaska, Delaware, Hawaii, Indiana, Kentucky, Montana, Nevada, New Mexico, North Dakota, Oklahoma, Rhode Island, South Dakota, Utah,
West Virginia, Wyoming.

b.

“Stranded” is generally used to refer to SNF stored where the nuclear reactor that generated the SNF has ceased operating and been decommissioned, and the SNF
remains at the site. In some cases the wet storage pools have been dismantled and the SNF is stored in dry casks. In the case of the Morris, IL, site, the “stranded” SNF

CRS-20

was shipped from other reactor sites for a proposed reprocessing facility that never operated, and no reactor has ever operated at the site. The number of “stranded”
SNF storage sites here does not include sites where SNF from decommissioned reactors is stored at sites co-located with operating reactors (e.g., San Onofre (CA),
Dresden 1 (IL), or Indian Point (NY)). This table includes U.S. DOE facilities in Colorado, Idaho, South Carolina, and Washington that store commercial SNF, but
where reactors have ceased operating, largely in the 1980s.
c.

Includes the Morris, IL, site, operated by GE-Hitachi, which never hosted an operating reactor or generated any SNF. The site was built to serve as an SNF
reprocessing plant for which the SNF from other sites was shipped. The facility never operated, and the SNF has remained stored at the site. Many sources categorize
the Morris site with dry cask storage sites, because they are all considered “Independent Spent Fuel Storage Installations” (ISFSI), although the Morris Site differs from
other ISFSIs because it uses wet pool storage and is categorized accordingly here.

d.

Excludes SNF and debris generated at the Three Mile Island-2 facility removed after the 1979 incident and shipped to DOE’s Idaho National Engineering Laboratory
(now referred to as “Idaho National Laboratory”) .

e.

Includes 29 MTU of SNF, fragments, and nuclear materials stored at the Savannah River Site (SRS) near Aiken, which has been operated by DOE for nuclear weapons
material production. In addition to material generated there, the SRS is used to store SNF shipped from commercial reactors (e.g., Carolinas-Virginia Tube Reactor)
and from foreign and domestic research reactors using U.S.-origin fuel.

f.

Does not include SNF shipped to DOE federal facilities: 8 MTU from Florida, 1 MTU from Maryland, 12 MTU from Michigan, 16 MTU from New York, 22 MTU from
Virginia, and 4 MTU from Wisconsin, as well as part of the SNF from the Fort St. Vrain site in Colorado, which was shipped to Idaho.

g.

Does not include SNF shipped to the Morris, IL, facility (see (b) above) from 4 states: 100 MTU from California, 34 MTU from Connecticut, 185 MTU from Minnesota,
and 191 MTU from Nebraska. Includes 132 MTU shipped from other facilities in Illinois to the Morris facility.

h.

The adjacent Salem 1 and 2 and Hope Creek reactors share dry cask storage facilities and could be considered three facilities on a single contiguous site.

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U.S. Spent Nuclear Fuel Storage

Sixty-three SNF storage sites also have operating commercial nuclear power reactors. At 10
commercial sites92 and an additional four DOE-operated sites,93 SNF is being stored where there
is no operating reactor. At these “stranded” SNF storage sites, the nuclear reactors that generated
the SNF have been shut down and at least partly decommissioned.94 Virtually none of the SNF at
these reactors has been moved from where it was generated to another site. In some cases, where
reactors have been shut down and decommissioned, the SNF has been moved to another reactor
site for storage. Most SNF storage is located in or near the operating nuclear reactor (or sister
reactors) that originally generated the SNF (see Table 1).
The SNF storage at nine commercial sites where reactors have been shut down has warranted
special attention by some in the nuclear industry, plant operators, utilities, and public service
commissions monitoring costs. These stranded sites represent roughly half of the sites where
reactors have shut down, but where SNF continues to be stored. Because these stranded sites do
not share overhead costs (e.g., security, maintenance and utilities) with a larger operating reactor
complex, the incremental storage costs are higher than at operating reactor sites.
At several other commercial sites (e.g., Millstone 1, CT; Dresden 1, IL; Indian Point 1, NY; and
San Onofre, CA), SNF is stored at facilities where a reactor has ceased operating but other
reactors at the same site continue operating.95 In addition, SNF is stored at three DOE-owned sites
where the reactors ceased operating.96 At one commercial site in Colorado (Fort St. Vrain), the
DOE operates an SNF storage facility from a reactor that shut down in 1989. More than 90% of
the stranded commercial SNF is located at five sites. Where SNF remains stored in dry cask
storage but no wet storage pool exists, there is some concern that this could make it difficult to
repackage the SNF if the need arises because SNF transfers are generally done under water.
The Blue Ribbon Commission (BRC) concluded that the need to address this stranded SNF was
one of “several compelling reasons to move as quickly as possible to develop safe, consolidated
storage capacity on a regional or national basis,” which it argued was “[t]he fundamental policy
question for spent fuel storage.”97

92

Included nine former commercial reactor sites and the GE-Hitachi site in Morris, IL.
The four DOE sites with long-term SNF storage are the Hanford Site (WA), Savannah River Site (SC), the Idaho
National Laboratory (ID), and the Fort St. Vrain Site (CO). In addition, DOE has indicated that relatively small
amounts of SNF (less than 50 kg at each) are stored at other sites including the Argonne National Laboratory (IL) and
the Babcock and Wilcox facility in Lynchburg, VA. Also, several university research reactors temporarily store SNF. A
total of about 3 MTU of SNF is stored at these various sites for which DOE provides support, away form the four main
sites.
94
One exception is the GE-Hitachi site in Morris, IL, which may be grouped with “stranded” sites, although it never
hosted an operating nuclear reactor, but rather was intended for an SNF reprocessing plant (that never operated), for
which the SNF was shipped.
95
The term “stranded” is used to refer to situations where SNF is stored but the associated reactor is no longer
operating and generating revenue to help pay for storage costs, despite the presence of associated reactors at the same
site.
96
In addition to the three former nuclear weapons material production facilities, DOE is also responsible for the storage
of SNF located at the former Fort St. Vrain reactor site in Colorado, which now hosts a commercial natural gas power
plant.
97
Blue Ribbon Commission on America’s Nuclear Future, Report to the Secretary of Energy, January 2012.
http://brc.gov/sites/default/files/documents/brc_finalreport_jan2012.pdf. See page 35.
93

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Figure 5 shows generally that most of the SNF storage in the United States is located in the
Midwest and on the East Coast. Specifically, measured by mass, more than 80% (54,092 MTU vs.
13,358 MTU) of SNF is stored at sites east of the Mississippi River. Measured by number of SNF
assemblies, however, nearly 84% (197,002 assemblies) of the SNF is stored in eastern sites
compared to approximately 17% (40,051 assemblies) stored in western sites.
Figure 5. Spent Nuclear Fuel Storage Map

Source: Map prepared by CRS Graphics staff primarily using data from the Nuclear Energy Institute report
“2011 Used Fuel Data,” by Gutherman Technical Associates, January 14, 2012. See Table 1 for more detail.
Notes: This map generally reflects storage quantities and location of commercial SNF, although relatively small
quantities of commercial SNF are stored at U.S. DOE facilities. The map does not include SNF stored at U.S.
DOE sites, which is a small portion (less than 4%) of total stored SNF.

The fact that BWR fuel assemblies are, individually, about half the mass of PWR fuel assemblies,
combined with the fact that there are a disproportionate number of BWRs in the East compared
with the overall number nationally,98 helps explain why there is a greater share of SNF counted by
assemblies, compared to the SNF mass (MTU), in the East.
98

Approximately two-thirds of the nuclear power reactors built in the United States have been PWRs, while about onethird have been BWRs. A disproportionate number of the reactors built in the west (72%) were PWRs, whereas a
somewhat larger percentage of the reactors built in the East were BWRs (36%). Approximately 80% of the total
number of reactors built in the United States were built in the East, compared to about 25% in the West. Of the 40
BWRs built in the United States, more than 80% were in the East. Of the 76 PWRs built, however, about 75% were
built in the eastern half of the United States.

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Measured by mass of SNF, there is a slightly higher percentage (83%) of SNF stored in wet pools
(40,260 out of 54,092 MTU) at eastern sites compared to the national share of SNF in wet storage
(73%, or 49,338 out of 67,450 MTU). The corollary is that there is a somewhat disproportionate
amount of SNF stored in dry casks at western sites (32%, or 4,280 out of 13,358 MTU) compared
to the national distribution of about 27%.
Measured by number of assemblies, the disproportionate number of assemblies (86%, or 172,443
out of 237,053 assemblies) stored in wet pools in the East is greater than the share of wet pool
storage at the western sites (15%, or 25,009 out of 40,051 assemblies), and greater than the
national distribution (73%, or 172,443 out of 237,053 assemblies). It is not clear what accounts
for this disproportionate share of SNF in dry cask storage at the western sites other than operator
preference. Given the smaller size of BWR elements and the disproportionate share of BWRs
located at eastern sites, however, it is predictable that the same disproportionate share of SNF by
mass is amplified when measured by number of assemblies.
Measured by metric tons of heavy metal content (MTU), the five states with the largest total
amount of SNF stored are
•

Illinois (8,691 MTU),

•

Pennsylvania (6,065 MTU),

•

South Carolina (4,044 MTU; 4,073MTU with DOE SNF),

•

New York (3,577 MTU),99 and

•

North Carolina (3,562 MTU).

The top five states with the largest amount (by MTU) of SNF stored in wet pools are
•

Illinois (6,900 MTU),

•

Pennsylvania (4,606 MTU),

•

New York (3,082 MTU),

•

North Carolina (3,018 MTU), and

•

Alabama (2,647 MTU).

The top five states with the largest amount (by MTU) of SNF in dry storage systems are
•

South Carolina (1,808 MTU),

•

Illinois (1,791 MTU),

•

Virginia (1,477 MTU),

•

Pennsylvania (1,459 MTU), and

•

California (916 MTU).

99
Excludes two 132-liter drums of SNF stored at the West Valley site near Buffalo, NY. See Margaret Loop and
Laurene Rowell, “Getting West Valley Demonstration Project Waste in the Right Path to Disposal,” Waste
Management 2011, February 27, 2011.

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The rankings change somewhat if measured by the number of SNF assemblies depending on the
portion of different types of reactors in each state (i.e., states with more BWRs have more
assemblies per MTU than states with more PWRs).
Measured by number of SNF assemblies, the five states with the largest total amount of SNF
stored are
•

Illinois (37,867 assemblies),

•

Pennsylvania (29,322 assemblies),

•

New York (14,286 assemblies),

•

Alabama (13,158 assemblies), and

•

North Carolina (12,092 assemblies).

The top five states with the largest amount (by assemblies) of SNF stored in wet pools are
•

Illinois (28,242 assemblies),

•

Pennsylvania (20,898 assemblies),

•

New York (12,466 assemblies),

•

Alabama (10,978 assemblies), and

•

North Carolina (10,612 assemblies).

The top five states with the largest amount (by assemblies) of SNF in dry storage systems are
•

Illinois (9,625 assemblies),

•

Pennsylvania (8,424 assemblies),

•

South Carolina (3,896 assemblies),

•

Georgia (3,264 assemblies), and

•

Virginia (3,229 assemblies).

Generally, the total amount of SNF in storage increases by approximately 2,000 MTU per year in
the United States, assuming current operation of about 104 commercial U.S. power reactors. The
amount of SNF stored in dry casks versus wet pools reflects more year-to-year changes
depending on decisions made by individual plant operators.
Historically, DOE and its predecessor agencies100 accepted for storage and reprocessing
significant amounts of spent nuclear fuel from commercial nuclear power plants. For example,
DOE took possession of the spent fuel and debris from the 1979 Three Mile Island plant incident,
and shipped it to a DOE facility in Idaho101 as part of a “research and development” project. In
addition, SNF was shipped to New York (West Valley) and Illinois (Morris), where the Atomic
Energy Commission, a predecessor to DOE, was involved in reprocessing efforts. In the 1970s a
relatively small amount (248.7 MTU) of commercial SNF was shipped from commercial reactors,
100
101

Atomic Energy Commission and the Energy Research and Development Administration.
The Idaho National Laboratory, known previously as the Idaho National Engineering Laboratory.

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including utilities in Michigan and New York, to the West Valley site in New York,102 which
reprocessed SNF for about six years (1966 to 1972). The resulting high-level waste and
contaminated facilities remain at the site. DOE has estimated that decommissioning and
environmental remediation of the contamination at the West Valley site will continue until at least
2020, cost $3.7 billion, and require indefinite long-term stewardship thereafter.103 The DOE sites
in South Carolina and Idaho have also accepted relatively small amounts of SNF from research
reactor SNF, some of which contains high-enriched uranium.
This report does not attempt to estimate the storage capacity of the existing facilities or sites. To
do so would require judgments and determinations about the potential for and safety of re-racking
SNF in more dense configurations that are beyond the scope of the analysis.

SNF Management by the U.S. Department of Energy
The U.S. Department of Energy (DOE) has direct responsibility for storage of SNF and other
reactor-irradiated nuclear materials at four sites: Fort St. Vrain (CO), Idaho National Laboratory
(ID), Savannah River Site (SC), and Hanford Reservation (WA).104 Because much of the DOE
inventory includes material that is fundamentally different from commercial SNF (e.g.,
enrichment level/U-235 concentration, cladding, size, condition), it is not appropriate to list and
sum these materials with commercial SNF.
A detailed description of this DOE-owned inventory is beyond the scope of this report, which is
focused on commercial SNF stored at commercial sites. A brief summary, however, helps explain
why it is accounted for separately in analyzing storage status issues and options. DOE and its
predecessor agencies operated a number of nuclear reactors for weapons material production105
and research. Although DOE ceased operating its large production reactors in the late 1980s and
early 1990s, it continues to produce and accept SNF from research reactors. Much of the SNF
from these reactors was reprocessed to extract certain nuclear materials (e.g., plutonium), which
generated liquid high-level waste, which is intended, after processing, to be disposed of in a
permanent geological repository with SNF. Some of DOE’s SNF has not been reprocessed and
remains stored as solid SNF.
In the case of the Savannah River Site (SRS), for example, there is a wide range of irradiated
nuclear materials, including aluminum-based nuclear fuel, “higher actinide targets,” and nonaluminum based fuel that DOE has characterized as “assemblies/items.”106 Like the SRS, the SNF
102
U.S. DOE, Spent Fuel Storage Requirements 1994-2042, DOE/RW-0431-Rev.1, June 1995; and United States Court
of Appeals for the District of Columbia Circuit, State of New York, et al.; Petitioners, Nos. 11-1045, 11-1051, -against11-1056, 11-1057 Nuclear Regulatory Commission, and United States of America, Respondents.
103
U.S. DOE, The 1996 Baseline Environmental Management Report, USDOE/EM-0290, June 1996.
104
Frank Marcinowski, Overview of DOE’s Spent Nuclear Fuel & High Level Waste; Presentation to the Blue Ribbon
Commission on America’s Nuclear Future, U.S. DOE, March 25, 2010.
105
These reactors, and the nuclear driver fuel and target assemblies in them, were designed for production of nuclear
materials including weapons grade (Pu-239) and other forms of plutonium (e.g., Pu-238 for durable power sources),
tritium, and neptunium.
106
U.S. DOE Idaho Office, Kathleen Hain, Idaho Site Spent Nuclear Fuel; Management, Presentation to the Nuclear
Waste Technical Review Board, June 2010; U.S. DOE Inspector General Office of Audit Services, Management of
Spent Nuclear Fuel at the Savannah River Site (DOE/IG-0727), May 2006; U.S. DOE, Savannah River Site, Spent
Nuclear Fuel Management Environmental Impact Statement (DOE/EIS-0279), March 2000; and U.S. DOE (Dawn
(continued...)

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at DOE’s Hanford site was largely surplus material from reactors used to produce materials (e.g.,
plutonium) for nuclear warheads, which was extracted using reprocessing facilities at the sites.
The design of these fuel elements intended to be reprocessed for weapons material was different
from commercial fuel elements (e.g., thin cladding). The Idaho inventory includes SNF from the
Naval Nuclear Propulsion program (i.e., submarines and aircraft carriers), which is different from
commercial SNF in multiple ways, including enrichment level and design. From about 1952 to
1992 this Navy SNF was reprocessed in Idaho to extract high-enriched uranium for use in driver
rods at weapons material production reactors elsewhere.107 The Idaho site is also home to the SNF
debris from the partial meltdown of the Three Mile Island (PA) reactor in 1979. The DOE sites
also store a variety of research reactor SNF—both foreign and domestic—that is often much
smaller (e.g., 3 to 4 feet long vs. 12 to 15 feet long for commercial power reactor fuel) and more
highly enriched than commercial reactor SNF. Some SNF stored at DOE sites came from
commercially related activities, including commercial power reactors (e.g., Three Mile Island),108
test reactors used for academic research (e.g., at 24 U.S. universities),109 medical isotopes, and
commercial power reactor research.110 By the late 1980s, some of the SNF at DOE sites had
become severely corroded or was stored in technically inadequate conditions. After 1993, DOE
undertook a “Spent Fuels Vulnerabilities Assessment” and developed detailed “Materials in
Inventory” plans to secure this material through packaging and processing, which have been
partially implemented generally in conformance with recommendations of the Defense Nuclear
Facilities Safety Board.
DOE-owned spent fuel includes some production reactor fuel, which has a fundamentally
different design and construction from commercial spent fuel. This DOE-owned production
reactor fuel generally has very thin cladding intended to facilitate reprocessing to recover
plutonium or other nuclear materials. DOE, with recommendations of the Defense Nuclear
Facilities Safety Board, has had a long-term plan to stabilize the relatively thin-walled DOEowned SNF because it is less robust than commercial SNF, which has thicker and more corrosionresistant cladding.111
The total amount of DOE-owned SNF and other reactor-irradiated material is about 198 MT, of
which about half is stored in wet storage pools and the other half in various dry storage
(...continued)
Gillas), SRS Used Nuclear Fuel Management: A Presentation to the Citizens Advisory Board, July 2011.
107
Thomas B. Cochran. Robert S. Norris, W. Arkin, and M. Hoenig (Natural Resources Defense Council), Nuclear
Weapons Databook, Vol. II, U.S. Nuclear Warhead Production, Ballinger Publishing Company, Cambridge, MA, 1987.
See http://docs.nrdc.org/nuclear/files/nuc_87010103a_65c.pdf.
108
Largely core debris and damaged SNF from the Three Mile Island reactor. This was generally an exceptional
situation, and most commercial reactor SNF is not sent to DOE facilities.
109
Douglas Morrell, DOE Research Reactor Infrastructure Program: 2011 Status Report, September 14, 2011. See
https://secure.inl.gov/TRTR2011/Presentations/Morrell_TRTR2011.pdf.
110
For example, core debris resulting from the 1979 incident at the Three Mile Island-2 reactor in Pennsylvania, and
commercial power demonstration projects at Shippingport and Peach Bottom in Pennsylvania, the Carolinas-Virginia
Tube Reactor in South Carolina, Fort St. Vrain reactor in Colorado, and Sodium Reactor Experiment at the Santa
Susanna Field Laboratory in California.
111
Defense Nuclear Facilities Safety Board, “Review of the Hanford Spent Nuclear Fuel Project Defense Nuclear
Facilities Safety Board,” DNFSB/TECH-17, Technical Report, October 1997; Defense Nuclear Facilities Safety Board,
“Technical Report: Stabilization of Deteriorating Mark 16 and Mark 22 Aluminum-Alloy Spent Nuclear Fuel at the
Savannah Rover Site,” DNFSB/TEC-7, June 1, 1995; and Defense Nuclear Facilities Safety Board, “Recommendation
to the Secretary of Energy 94-1; Improved Schedule for Remediation of Nuclear Materials in the Defense Nuclear
Facilities Complex,” May 26, 1994.

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configurations. All of the SNF at the Hanford and Fort St. Vrain sites has been transferred to dry
casks, while all of the material at the SRS is stored in wet storage pools. The Idaho site employs
both methods.
In addition to the different types of SNF and other reactor-irradiated material at DOE sites, DOE
is also responsible for high-level waste (HLW) resulting from reprocessing of SNF. Hence, it
could be misleading to simply sum the SNF at the DOE-owned sites with the SNF stored at
commercial sites, possibly implying a total inventory of HLW intended for extended storage and
eventual repository disposal. The SNF inventories at DOE sites must be accounted for separately
from commercial sites to compile a meaningful assessment of the total inventory of HLW in the
United States. At the Hanford site, the HLW remains stored in underground tanks (many of which
have leaked into the ground) awaiting treatment. At the West Valley site in upstate New York, the
HLW from SNF reprocessing has largely been vitrified into a borosolicate glass inside stainless
steel canisters and awaits disposal. Some of the HLW at the SRS has been similarly treated on a
larger scale. At the Idaho sites, the HLW from reprocessing of SNF is being stored in both a liquid
form and a solid calcine form awaiting treatment to prepare for disposal. The details of HLW
storage, treatment facility construction and operations, “waste incidental to reprocessing,” glass
log disposition, tank closure, and costs are beyond the scope of this report.112
Moreover, the exact inventory of SNF and irradiated materials at DOE sites is more variable than
commercial SNF. In some cases DOE may use the SRS reprocessing “H-canyon,” for which DOE
is required by law to “maintain a high state of readiness”113 to reprocess materials for recovery of
nuclear materials or to stabilize materials for safety reasons.114 DOE recently announced its
intention to use the H-canyon to process plutonium non-pit scrap.115 Although the exact inventory
is difficult to compare because of qualitative differences, such as the non-pit scrap, it is useful to
put in context the total SNF inventory at DOE sites to the overall totals. The 29 MTU of SNF at
the Savannah River Site comprise about 1.2% of the DOE-owned SNF, and about 0.04% of the
total SNF stored in the United States. After reprocessing, the SNF would be converted to a
relatively small amount of fissile material, and a larger volume of liquid acidic radioactive waste
containing much of the fission products. This liquid radioactive waste would be pumped into
underground tanks and (minus any “Waste Incidental to Reprocessing”)116 ultimately processed
into borosilicate glass logs inside stainless steel canisters destined for disposal in a permanent
geological repository. The path forward for this material is beyond the scope of this report.

112
See CRS Report RS21988, Radioactive Tank Waste from the Past Production of Nuclear Weapons:
Background and Issues for Congress, by (name redacted) and (name redacted).
113
FY 2001 Defense Authorization Act, P.L. 106-398, Section 3137.
114
Defense Nuclear Facilities Safety Board, “Recommendation to the Secretary of Energy 94-1.”
115
DOE National Nuclear Security Administration, “Press Release: NNSA Announces H-Canyon to Support Plutonium
Disposition at the Savannah River Site,” October 31, 2011 (see http://nnsa.energy.gov/mediaroom/pressreleases/
hcanyon); and George Lobsenz, “NNSA to Process Plutonium for MOX at H Canyon,” Energy Daily, November 2,
2011.
116
See CRS Report RS21988, Radioactive Tank Waste from the Past Production of Nuclear Weapons:
Background and Issues for Congress, by (name redacted) and (name redacted).

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Hazards and Potential Risks Associated with
SNF Storage
Evaluating hazards and risks accurately and with sufficient precision is essential to making
decisions about SNF management and regulation. The primary near-term hazard from SNF
derives from the radioactivity from the decay of mixed fission products (e.g., cesium-137,
strontium-90), and long-term hazards from plutonium and uranium. Hence, spent nuclear fuel
generally poses a significant hazard but it may not pose a significant risk, depending on how it is
managed. The distinction between “hazard” and “risk” is fundamental to analyzing the need for
and benefits of various SNF management options. In classic risk assessment and toxicology, a
hazard is the inherent potential of something to cause harm, whereas a risk is generally the
product of a probability and the severity of an event (e.g., health, environmental, or financial
impact). Whether a hazardous substance poses a risk depends on a variety of factors, including
containment and exposure. For example, to the extent that spent fuel is effectively contained, the
hazard can remain extremely high, but the risk may be low because there is no pathway for
exposure.117
Regulation of SNF storage requires a consideration of risk, which involves characterizing the
probability and consequence of potential threats. Regulation also requires a policy judgment
about what level of assurance is warranted. Some would argue that the hazard, or consequence
from the event, is so high that it demands a commensurately high level of protection, using any
available technology, against threats to prevent any significant risks to human health and the
environment.118 Others, including a former NRC commissioner, have argued that the mandate of
NRC is to “provide reasonable assurance of adequate protection, not absolute assurance of perfect
protection.”119
Although the thermal heat and radiation from SNF begins to drop as soon as the fission process
ceases upon reactor shutdown, SNF assemblies continue to require cooling and shielding during
storage after discharge from a reactor. Generally, SNF requires three to five years of wet pool
storage before it has cooled enough for transfer to dry cask storage. While NRC has authorized
transfer as early as three years, the industry norm is about 10 years. Some analysts and observers
have expressed concern about the safety of current spent nuclear fuel management practices, at
least for long-term storage methods.120 Until the recently proposed termination of the Yucca
Mountain repository project, however, these SNF storage methods were not generally considered
“long-term.”
117

See National Academy of Sciences/National Research Council, “Risk Assessment in the Federal Government:
Managing the Process,” Committee on the Institutional Means for Assessment of Risks to Public Health, National
Academy Press, Washington, DC, 1983; and Klaassen CD, Amdur MO, Doull J., Casarett & Doull’s Toxicology: The
Basic Science of Poisons, Macmillan Publishing (3rd Ed, 1986).
118
Alvarez, Robert, Spent Nuclear Fuel Pools in the U.S.: Reducing the Deadly Risks of Storage, Institute for Policy
Studies, May 2011.
119
Wald, Matthew L., “Edward McGaffigan, 58, Atomic Official,” New York Times, September 4, 2007. The term
“adequate protection” is a term of art under Section 182 of the Atomic Energy Act of 1954. 42 U.S.C. 2232.
120
Lisbeth Gronlund, David Lochbaum, and Edwin Lyman, Nuclear power in a warming world; Assessing the Risks,
Addressing the Challenges, Union of Concerned Scientists, December 2007; Lochbaum, David, Nuclear Waste
Disposal Crisis, Penn Well Books, Tulsa OK, 1996; Newsday Editorial, “Time to act on perilous piles; Memo to
Congress: Do something now about our spent nuclear fuel,” Newsday, April 22, 2011.

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NRC and others have viewed SNF storage as a relatively safe operation, if reasonable precautions
are exercised and normal conditions prevail. The inherent hazards of SNF, however, can result in
a variety of risks under other conditions. A variety of forces or “threats” acting on spent fuel
could result in containment being breached, resulting in potential exposures and risks, generally:
(1) loss of power for water supply, circulation, or cooling, which can have significant
consequences for SNF in wet pool storage;121 (2) external threats, like hydrogen explosions from
adjacent reactors, or an airplane crashing onto an SNF storage facility; (3) long-term degradation
of SNF through chronic corrosion of cladding (e.g., hydride corrosion); and (4) leakage of
contaminated water from wet pools to groundwater.
After the earthquake and tsunami in Japan, the first two of these concerns appeared to be
occurring at the Fukushima Dai-ichi facility. In testimony on March 16, 2011, before a joint
subcommittee hearing of the House Energy and Commerce Committee, NRC chairman Greg
Jaczko stated that, following the hydrogen explosion at reactor #4 at the Fukushima Dai-ichi
plant, there was an uncovering of the fuel in the pool and there was “no water in the pool.”122 A
November 2011 report by the Institute for Nuclear Power Operations concluded that
“[S]ubsequent analyses and inspections determined that the spent fuel pool water levels never
dropped below the top of fuel in any spent fuel pool and that no significant fuel damage had
occurred. Current investigation results indicate that any potential fuel damage may have been
caused by debris from the reactor building explosions.”123
Less than a week after the earthquake and tsunami, and two days after this testimony, NRC
published a nonregulatory information notice to reactor operators to “review the information for
applicability to their facilities and consider actions, as appropriate, to avoid similar problems.”124
This information notice reiterated NRC’s process for adopting earlier Interim Compensatory
Measures,125 which dealt with spent fuel storage safety, among other issues. This initial NRC
notice summarized the circumstances, indicating that “Units 3 and 4 have low spent fuel pool
(SFP) water levels.”126
A recent study by the Massachusetts Institute of Technology (MIT), soon after the Fukushima
Dai-ichi incident, recommended that NRC and the nuclear power industry
reexamine safety systems, operating procedures, regulatory oversight, emergency response
plans, design basis threats, and spent fuel management protocols for operating U.S. reactors.
Some of these issues were addressed in the aftermath of the TMI-2 accident and the
121
After several years in pool storage, the thermal heat load from SNF drops significantly, and less heat removal from
the water may be required. Nonetheless, the water continues to serve an important radiation shielding function.
122
Jaczko, Honorable Greg, NRC Chairman, Statement before the Joint Hearing of the Subcommittee on Energy and
Power and the Subcommittee on Environment and the Economy of the House Energy and Commerce Committee, “The
FY2012 Department of Energy and Nuclear Regulatory Commission Budgets,” March 16, 2011,
http://energycommerce.house.gov/hearings/hearingdetail.aspx?NewsID=8329.
123
Institute for Nuclear Power Operations, Special Report on the Nuclear Accident at the Fukushima Daiichi Nuclear
Power Station, INPO 11-005, Rev. 0, November 2011, at page 35; http://www.nei.org/resourcesandstats/
documentlibrary/safetyandsecurity/reports/special-report-on-the-nuclear-accident-at-the-fukushima-daiichi-nuclearpower-station.
124
U.S. Nuclear Regulatory Commission, Information Notice 2011-05, Tohoku-Taiheiyou-Oki Earthquake Effects on
Japanese Nuclear Power Plants, March 18, 2011.
125
U.S. NRC, “Order for Interim Safeguards and Security Compensatory Measures,” EA-02-026, February 25, 2002
(designated Safeguards Information, protected as “Official Use Only-Security Related Information”).
126
Ibid.

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September 11 World Trade Center attacks, resulting both in hardening of U.S. nuclear plants
against a number of accident scenarios and in improved emergency response preparations.127

The Government Accountability Office has recommended DOE “[a]ssess the condition of
existing storage facilities and identify any gaps and actions that might be needed to address longterm storage requirements.”128
In the wake of the Fukushima Dai-ichi incident, NRC dispatched inspectors to each U.S. reactor
and SNF storage site. The results of these inspections varied with different sites, with NRC
inspections revealing no significant vulnerabilities for most sites. For sites with the oldest SNF
(e.g., at the GE-Hitachi Morris storage site in Illinois), the predicted impact of an extended loss of
power to the site would be minimal because of the extent of the radioactive decay during the
decades of storage. NRC predicted that, “in the unlikely event that the [spent fuel wet storage
basin] is completely drained of water, fuel melt would not occur given the limited fuel decay heat
load.”129
The Fukushima Dai-ichi incident raised concerns about possible risks to SNF storage, including
physical damage and loss of power. Although details remain unclear, the dramatic gas explosions
that caused some of the overhead containment structure to collapse down into the pool appeared
to have caused little or no damage to the SNF in the pools.130 Also, despite the loss of power over
an extended period and some loss of cooling water, the SNF in the storage pools appeared to have
remained covered in water largely undamaged.
Notwithstanding these initial results on the SNF condition at the Fukushima Dai-ichi site, some
analysts are concerned that, under some circumstances, SNF zirconium cladding can catch fire if
left uncovered in wet storage pools. The National Academies/National Research Council
concluded, based primarily on review of NRC studies,131 “that a loss-of-pool-coolant event could
trigger a zirconium cladding fire in the exposed spent fuel,” but considered “such an accident ...
so unlikely that no specific action was warranted.”132 NRC has issued a series of orders and letters
to licensees to implement additional mitigation measures to address the issue.133 NRC and others,
including the nuclear industry, believe these actions provide reasonable assurance of adequate
protection. Others disagree, including a long-time nuclear critic who has argued that the large
inventory of radioactive material in wet pools poses a significant risk if the SNF pools were
127

Massachusetts Institute of Technology, The Future of the Nuclear Fuel Cycle: An Interdisciplinary MIT Study, MIT,
Cambridge, MA, 2011.
128
U.S. Government Accountability Office, DOE Nuclear Waste: Better Information Needed on Waste Storage at DOE
Sites as a Result of Yucca Mountain Shutdown, GAO-11-230, March 2011.
129
Lipa, Christine A., U.S. NRC, NRC Inspection Report No. 072-00001/11-01(Dnms)—General Electric-Hitachi
Morris, Letter to Mark Varno, GE-Hitachi Global Laser Enrichment, LLC, May 13, 2011.
130
Institute for Nuclear Power Operations, “Special Report on the Nuclear Accident at the Fukushima Daiichi Nuclear
Power Station,” INPO 11-005, Rev. 0, November 2011, at page 35 (http://www.nei.org/resourcesandstats/
documentlibrary/safetyandsecurity/reports/special-report-on-the-nuclear-accident-at-the-fukushima-daiichi-nuclearpower-station.)
131
For example, see U.S. NRC, Technical Study of Spent Fuel Pool Accident Risk at Decommissioning Nuclear Power
Plants, NUREG-1738, 2001.
132
National Academy of Sciences, National Research Council, Safety and Security of Commercial Spent Nuclear Fuel
Storage: Public Report, National Academies Press 2006 (based on classified July 2004 report to Congress), at page 44.
133
Letter from Nils Diaz, Commissioner, U.S. NRC to Senator Pete Domenici, with accompanying report: U.S.
Nuclear Regulatory Commission, Report to Congress on the National Academy of Sciences Study on the Safety and
Security of Commercial Spent Nuclear Fuel Storage, March 14, 2005.

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drained of water, the SNF were uncovered, and there was a release from an incident such as a fire
or deliberate attack.134
The locations of SNF wet pool storage in relation to the associated nuclear reactor may present
potential risks associated with those designs. For example, most boiling water reactors (BWRs) in
the United States, including the GE Mark I, are designed with the SNF storage pool located inside
the same secondary containment structure as the reactor and many critical control systems, and
located well above ground level. Many have expressed concern that this design may pose safety
risks because any problems with the reactor can affect the SNF storage pools, and vice versa.135
For example, in a loss of off-site power situation, such as occurred at the GE Mark I reactors in
Fukushima, Japan, the SNF pool may also lose power, affecting the cooling water and monitoring
systems. In the case of the incident in Japan, elevated radiation near the reactor hindered
personnel from mitigating problems or monitoring the SNF storage pools. In addition, the height
of the SNF pools in many BWRs (more than 100 feet above ground level) could also pose safety
risks because of the elevated access challenge and potential for a loss of coolant in a structural
failure, compared to reactors with the SNF storage pools at or below ground level.
Prior to the Fukushima Dai-ichi incident, the biggest change in the risk profile for SNF storage
occurred in the wake of the September 11, 2001, terrorist attacks, after which a congressionally
mandated National Academy of Sciences report concluded that “attacks with civilian aircraft
remain a credible threat.”136 NAS indicated that terrorists might choose to attack spent nuclear
fuel pools because they are “less well protected structurally than reactor cores” and “typically
contain inventories of medium- and long-lived radionuclides that are several times greater than
those contained in reactor cores.”137 In response, NRC issued a series of orders and letters to
licensees, the contents of which are confidential. NRC also conducted site-specific evaluations to
review individual site risks and readiness, resulting in site modifications, the details of which are
also confidential. Although the reviews, orders, and letters resulted in numerous incremental
improvements to SNF storage facilities and operations, such as improved backup power supply
reliability, there was no large-scale shift of SNF out of wet pools and into dry casks, nor was there
a mandate to move SNF into hardened storage facilities.
By contrast, Germany explicitly requires protection against risks, including “external events”
such as an attack on SNF storage,138 and this has resulted in construction of hardened storage
buildings for dry cask storage of SNF.139 The Germans have also moved to establish consolidated
central SNF storage facilities in the wake of a 2005 decision to cease reprocessing, and the lack of
a geological repository.140

134

Robert Alvarez, Spent Nuclear Fuel Pools in the U.S.: Reducing the Deadly Risks of Storage, Institute for Policy
Studies, May 2011.
135
David Lochbaum, Nuclear Waste Disposal Crisis (Penn Well Books, Tulsa OK, 1996); Newsday Editorial, “Time to
act on perilous piles; Memo to Congress: Do something now about our spent nuclear fuel,” Newsday, April 22, 2011.
136
National Academy of Sciences, National Research Council, Safety and Security of Commercial Spent Nuclear fuel
Storage: Public Report (2006), E725-846.
137
Ibid. at 36.
138
Section 6 para. 2 no. 4 (German) Atomic Energy Act.
139
Ulrich Alter (Federal Ministry for the Environment and Nuclear Safety), Management of Radioactive Waste and
Spent Fuel in Germany, presentation to the IAEA Conference, May 31, 2010.
140
Jussofie, A., R. Graf, W. Filbert, German Approach to Spent Fuel Management, “IAEA-CN-184/30, 2010.z; and
Harold Feiveson, Zia Mian, M. V. Ramana, and Frank von Hippel, “Managing Nuclear Spent Fuel: Policy Lessons
(continued...)

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Another potential threat to SNF storage safety is degradation of the cladding141 and fuel elements.
The potential for degradation of SNF cladding has been well known for decades, and the water
chemistry of SNF storage pools is carefully controlled in part to protect against it.142 The potential
vulnerability of SNF varies with the particular type of fuel rod. Generally, however, the rate of
corrosion and embrittlement of typical U.S. light water reactor zircalloy-clad commercial fuel
rods is less than the rate for the British Magnox fuel rods, or DOE nuclear materials production
reactor fuel elements, which are intended for shorter periods inside the reactor.143 Hence, although
some have expressed concern that U.S. nuclear fuel was not designed for long-term storage,144
U.S. power reactor fuel has generally proven more durable than other fuel forms.
NRC concluded in its initial 1984 waste confidence rule “that the cladding which encases spent
fuel is highly resistant to failure under pool storage conditions,” and that “[c]corrosion studies of
irradiated fuel at 20 reactor pools in the United States suggest that there is no detectable
degradation of zircalloy cladding.”145 Nonetheless, BRC and NAS, among others, have
recommended long-term research projects to evaluate the integrity of stored SNF,146 such as
ongoing work by the Electr

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/crs%3AR42513. Public record. Not legal advice.