Report to the Chairman, 

Subcommittee on Energy and Air 

Quality, Committee on Energy and 

Commerce, U.S. House of 

Representatives 

United States General Accounting Office 

GAO 

July 2003 SPENT NUCLEAR 

FUEL 

Options Exist to 

Further Enhance 

Security 

GAO-03-426 
The likelihood of widespread harm from a terrorist attack or a severe 

accident involving commercial spent nuclear fuel is low, according to studies 

conducted by DOE and NRC. Largely because spent fuel is hard to disperse 

and is stored in protective containers, these studies found that most terrorist 

or accident scenarios would cause little or no release of spent fuel, with 

little harm to human health. Some assessments found widespread harm is 

possible under certain severe but extremely unlikely conditions involving 

spent fuel stored in storage pools. As part of its ongoing research program 

and to respond to increased security concerns, NRC has ongoing and 

planned studies of the safety and security of spent fuel, including the 

potential effects of more extreme attack scenarios, including deliberate 

aircraft crashes. 

While NRC and DOE have found that spent fuel may be relatively safe and 

secure, DOE could potentially enhance the security of this fuel through 

options such as minimizing the number of shipments and picking up fuel in 

an order that would reduce risk, such as moving older less dangerous fuel 

first. These options could reduce the risk during transport and at some 

locations where the fuel is currently stored. However, contractual 

agreements between DOE and owners of spent fuel may limit DOE's ability 

to choose among these options. In addition, it is not clear that the benefits 

of these measures would justify the potential costs, including a possible 

renegotiation of the contracts between DOE and the spent fuel owners. 

Spent nuclear fuel, the used fuel 

periodically removed from nuclear 

power reactors, is one of the most 

hazardous materials made by 

man. Nuclear power companies 

currently store 50,000 tons of spent 

fuel at 72 sites in 33 states. That 

amount will increase through 2010, 

when the Department of Energy 

(DOE) expects to open a 

permanent repository for this 

fuel at Yucca Mountain, Nevada. 

Concerns have been raised since 

September 11, 2001, that terrorists 

might target spent fuel. GAO 

was asked to (1) review federally 

sponsored studies that assessed 

the potential health effects of a 

terrorist attack or a severe accident 

on spent fuel, either in transit or 

in storage, and (2) identify options 

for DOE to further enhance the 

security of spent fuel during 

shipping to Yucca Mountain. 

GAO is recommending that, 

as DOE develops its plans for 

transporting spent fuel to Yucca 

Mountain, it assess potential 

options to further enhance the 

security and safety of this fuel. 

In commenting on GAO’s report, 

DOE and NRC generally concurred 

with the facts of the report. 

DOE noted that the information 

on transit was accurate and 

well-balanced, while the Nuclear 

Regulatory Commission (NRC) 

noted that the information provides 

a reasonable characterization of 

the current understanding of risks 

associated with spent fuel storage. 

www.gao.gov/cgi-bin/getrpt?GAO-03-426.

To view the full product, including the scope 

and methodology, click on the link above. 

For more information, contact Robin M. 

Nazarro at (202) 512-3841 or 

nazarror@gao.gov. 

Highlights of GAO-03-426, a report to the 

Chairman, Subcommittee on Energy and 

Air Quality, Committee on Energy and 

Commerce, U.S. House of 

Representatives 

July 2003 

SPENT NUCLEAR FUEL 

Options Exist to Further Enhance 

Security 
Page i GAO-03-426 Spent Nuclear Fuel 

Letter 1

Results in Brief 2

Background 3

Likelihood of Widespread Harm from Terrorist Attacks or Severe 

Accidents Involving Spent Fuel Is Low 8

Options May Exist to Further Enhance Security and Safety 17

Conclusions 24

Recommendations for Executive Action 24

Agency Comments and Our Evaluation 24

Scope and Methodology 26

Appendix I Nuclear Regulatory Commission Requirements for 

Safety and Security of Spent Fuel 28 

Appendix II Additional Information on Studies on the Safety and 

Security of Spent Fuel in Transit 37 

Appendix III Comments from the Department of Energy 42 

Appendix IV Comments from the Nuclear Regulatory Commission 43 

Appendix V GAO Contact and Staff Acknowledgments 45 

Table 

Table 1: Potential Health Effects of Fire in a Spent Fuel Pool 14

Contents 
Page ii GAO-03-426 Spent Nuclear Fuel 

Figures 

Figure 1: Locations for Wet and Dry Storage Sites for Commercial 

Spent Nuclear Fuel and Yucca Mountain, as of April 2003 6

Figure 2: Cutaway Graphic of a Spent Fuel Truck 

Transportation Cask 29

Figure 3: Spent Fuel Rail Container 30

Figure 4: Spent Fuel Truck Container on a Trailer 30

Figure 5: A Wet Storage Pool 32

Figure 6: A Spent Fuel Dry Storage Container 35

Abbreviations 

DOE Department of Energy 

NRC Nuclear Regulatory Commission 

This is a work of the U.S. Government and is not subject to copyright protection in the 

United States. It may be reproduced and distributed in its entirety without further 

permission from GAO. It may contain copyrighted graphics, images or other materials. 

Permission from the copyright holder may be necessary should you wish to reproduce 

copyrighted materials separately from GAO’s product. 
Page 1 GAO-03-426 Spent Nuclear Fuel 

July 15, 2003 

The Honorable Joe Barton 

Chairman, Subcommittee on Energy and Air Quality 

Committee on Energy and Commerce 

House of Representatives 

Dear Mr. Chairman: 

One of the most hazardous materials made by man is spent nuclear 

fuel—the used fuel periodically removed from reactors in nuclear power 

plants. Without protective shielding, the fuel’s intense radioactivity can kill 

a person exposed directly to it within minutes or cause cancer in those 

who receive smaller doses. As the fuel ages, it begins to cool and becomes 

less radiologically dangerous—some of the radioactive particles decay 

quickly, within days or weeks, while others exist for many thousands 

of years. Currently, more than 50,000 tons of commercial spent fuel are 

stored at 72 sites at or near nuclear power plants in 33 states. Most of this 

nuclear fuel is stored immersed in pools of water designed to cool the fuel, 

but some sites also keep older, cooler fuel in “dry storage” units that 

generally consist of steel containers placed inside reinforced concrete 

vaults or bunkers. Concerns about the security of these sites and their 

spent fuel inventories have been raised following the terrorist attacks of 

September 11, 2001. 

To provide secure, permanent disposal for spent fuel, the President 

and the Congress have approved development of a deep underground 

repository at Yucca Mountain, Nevada. The Department of Energy (DOE) 

is to construct and operate the repository after receiving a license from the 

Nuclear Regulatory Commission (NRC). Shipping this fuel from current 

storage locations to Yucca Mountain will be managed by DOE, which in 

1983 entered into contracts with owners of spent fuel (essentially owners 

and operators of nuclear power plants) requiring DOE to take title to and 

dispose of this fuel. DOE estimates that 175 shipments per year over 

24 years will be required to move the accumulated inventory of spent 

nuclear fuel. These shipments have increased public concern about 

nuclear security. Recent media reports suggest that if terrorists could 

release spent fuel into the environment during transit or from wet or dry 

storage sites, particularly near large cities, the human health effects could 

be severe. 

United States General Accounting Office

Washington, DC 20548 
Page 2 GAO-03-426 Spent Nuclear Fuel 

We agreed with your office to (1) review federally sponsored studies that 

examined the potential health effects of a terrorist attack or a severe 

accident involving commercial spent nuclear fuel, either in transit or in 

storage, and (2) identify options for DOE to enhance the security of 

spent fuel as it develops its plans to ship the fuel to Yucca Mountain. In 

conducting our review, we did not assess the reliability of data or the 

methodologies used in the studies that examined potential health effects. 

We also did not examine economic or broader environmental effects of 

terrorist attacks or severe accidents, nor did we examine the effectiveness 

of certain other safety and security measures, such as the effectiveness of 

armed guards and intrusion barriers. 

NRC and DOE studies indicate a low likelihood of widespread harm to 

human health from terrorist attacks or severe accidents involving spent 

fuel—either in transit or dry or wet storage. Spent fuel is a heavy, ceramic 

material that is neither explosive nor volatile and resists easy dispersal. 

Tests to date on shipping containers and dry storage containers have 

shown that, while they can be penetrated under terrorist and severe 

accident scenarios, their construction allows little release of spent fuel, 

with little harm to human health. While release of a large quantity of 

radioactive material from a wet storage pool is theoretically possible, 

such a release would require an extremely unlikely chain of events. For 

example, coolant would have to be drained from pools and the fuel left 

uncovered for a sustained period. Studies reveal that such an event would 

be extremely unlikely to occur by accident. To supplement the existing 

body of work on the safety and security of spent fuel, NRC has 

commissioned additional studies to address technical uncertainties and 

respond to heightened security concerns. 

While NRC and DOE have found that spent fuel may be relatively safe and 

secure, DOE could potentially enhance the security of this fuel through 

options such as minimizing the overall number of shipments and picking 

up fuel in an order that would reduce risk, such as moving older, less 

dangerous fuel first. DOE’s ability to choose some of these options may be 

limited by its contracts with the fuel owners. These contracts generally 

require DOE to pick up increments of spent fuel based on the dates that 

the owners removed these amounts of fuel from their nuclear power 

reactors. Taken literally, the contracts would require DOE to pick up small 

amounts of spent fuel at reactor sites scattered across the country. For 

example, adhering to the shipping queue for the 12 largest nuclear power 

utilities would result in roughly 576 shipments. In contrast, revising the 

contracts to allow DOE to pick up larger quantities of fuel at each site 

Results in Brief 
Page 3 GAO-03-426 Spent Nuclear Fuel 

could eliminate about 300 of the shipments. The order in which spent fuel 

is shipped could also affect safety and security because certain fuel poses 

more risks based on its age and location. For example, shipping the oldest 

fuel first could enhance security in transit because this fuel is relatively 

less radiologically dangerous. However, DOE cannot unilaterally mandate 

this approach because the contracts allow the fuel owners to decide, once 

their turn in the shipping queue arrives, which increments of fuel from 

which of their nuclear plants will actually be shipped. Under contracts, 

owners could decide, based on operational needs, to ship younger, more 

radioactive fuel out of wet storage pools first before shipping fuel from dry 

storage—this choice could allow a fuel owner to free up needed space in a 

storage pool. We are recommending that, as DOE develops its plans for 

transporting spent fuel to Yucca Mountain, it identify and assess potential 

options to enhance the safety and security of this fuel. Exercising any of 

these options may require renegotiating aspects of its shipping contracts 

with fuel owners if necessary. 

We provided a draft of this report to DOE and NRC for review and 

comment. These agencies generally concurred with the facts of the report. 

DOE noted that the information on transit was accurate and balanced, and 

concurred with our recommendation with one exception. DOE noted that 

the Department of Transportation is conducting a study of the safety and 

security implications of transporting spent fuel by railroad trains that 

haul only spent fuel. DOE explained that it would prefer to wait for the 

outcome of this evaluation rather than duplicate efforts. NRC noted that, 

overall, the report provides a reasonable characterization of the current 

understanding of risks associated with spent fuel storage. NRC raised 

concerns about our references to two NRC studies in our report. NRC 

expressed concern that we needed to further emphasize NRC’s use of 

conservative assumptions in these two reports, such as the assumption 

that a fire in a spent fuel pool would involve 100 percent of the spent fuel 

assemblies in a pool. We revised the report to account for these concerns 

and added preliminary results from NRC’s ongoing work involving risks 

associated with spent fuel pools. 

Fuel for nuclear power plants consists of fingernail-sized pellets of 

uranium dioxide, a radioactive compound. The pellets are fitted into 

hollow metal rods, typically constructed of zirconium alloy, and the rods 

are then gas pressurized. The rods are generally 12 to 14 feet in length and 

are bundled together into assemblies. A portion of the assemblies must be 

replaced every 1 to 2 years as the fuel in the reactor expends energy, 

becoming less efficient at producing heat. As part of the process of 

Background 
Page 4 GAO-03-426 Spent Nuclear Fuel 

expending energy during a nuclear reaction, the fuel becomes highly 

radioactive and thermally hot. Spent fuel emits radiation as a consequence 

of radioactive decay. Barriers such as thick walls, sealed containers, and 

water are used to shield individuals from exposure to this radiation. 

NRC regulates not only the construction and operation of commercial 

nuclear power plants but also the storage, transportation (together with 

the Department of Transportation), and disposal of spent fuel. NRC 

requires each operating nuclear power plant to have safety and security 

programs. For example, NRC requires protective shielding and security 

systems, including armed guards, at nuclear power plants. When spent 

fuel assemblies are removed from a reactor, they are stored in large 

pools of cooling water. These pools are constructed according to NRC’s 

requirements, typically with 4- to 6-foot thick steel-lined concrete walls 

and floors. Pools are typically 30 to 60 feet long, 20 to 40 feet wide, and 

40 feet deep. The location of these pools is dependent on the type of 

reactor. Essentially, all commercial power reactors in the United States 

are one of two types, either a boiling water reactor or a pressurized water 

reactor.1

 For most boiling water reactors, the pools are located close to the 

reactors, several stories above ground. For pressurized water reactors, the 

pools are located in structures outside the reactor building, on the ground 

or partially embedded in the ground. Regardless of reactor type, these 

pools are required by NRC to be constructed to protect public health 

against radiation exposure, even after a natural disaster, such as an 

earthquake. The water in the pool is constantly cooled and circulated, and 

the fuel assemblies are generally 20 feet below the surface of the water. 

 1

 A boiling water reactor uses slightly radioactive steam that is generated in the reactor to 

drive a turbine that generates electricity. The water is returned to the reactor core where 

it is reheated to steam, driving the turbines as the cycle is repeated. Pressurized reactors 

send slightly radioactive pressurized water to a steam generator, which creates steam from 

nonradioactive water kept separated by tubes. The steam drives the turbine and the slightly 

radioactive water returns to the reactor where it is reheated and the cycle repeated. 
Page 5 GAO-03-426 Spent Nuclear Fuel 

In 1982, through the Nuclear Waste Policy Act, the Congress directed DOE 

to construct an underground repository for disposal of spent fuel and 

other high-level radioactive waste.2

 The Congress amended the act in 1987 

and required DOE to only consider Yucca Mountain, Nevada, as a potential 

site for a repository.3

 In 2002, the President recommended to the Congress, 

and the Congress approved, Yucca Mountain as a suitable site for the 

development of a permanent high-level waste repository. As we reported 

in 2001, for a variety of reasons, DOE is unlikely to open the repository as 

planned in 2010.4

Lacking a long-term disposal option now, some nuclear utilities must 

move a portion of their spent fuel into dry storage or face shutting down 

their plants because their wet pools are reaching capacity. Currently, 25 of 

the 72 storage sites use dry storage, and 11 other sites have plans to move 

some of their inventory of spent fuel into dry storage. Dry storage facilities 

for spent fuel typically consist of steel containers that are placed inside 

concrete vaults or bunkers where the fuel is cooled by air rather than 

water. These storage systems are required by NRC to be capable of 

protecting against radiation exposure and of surviving natural disasters. 

Because the move to dry storage is time-consuming and expensive, 

utilities are, wherever possible, modifying wet pool storage capacity so 

they can store larger quantities of spent fuel in these pools. 

 2

 This other waste is the result of nuclear activities from DOE—90 percent of the volume of 

waste expected to be shipped to the Yucca Mountain repository is expected to be spent 

fuel and the other 10 percent is expected to be DOE waste. 

3

 Yucca Mountain, Nevada, is located approximately 100 miles northwest of Las Vegas, 

Nevada. 

4

 U.S. General Accounting Office, Nuclear Waste: Technical, Schedule, and Cost 

Uncertainties of the Yucca Mountain Repository Project, GAO-02-191 (Washington, D.C., 

Dec. 21, 2001). 
Page 6 GAO-03-426 Spent Nuclear Fuel 

Figure 1: Locations for Wet and Dry Storage Sites for Commercial Spent Nuclear Fuel and Yucca Mountain, as of April 2003 
Page 7 GAO-03-426 Spent Nuclear Fuel 

To expose a large number of people to the harmful effects of radiation 

from spent fuel, the fuel would have to be released from its protective 

containers and dispersed over a wide or densely populated area. However, 

unlike many other hazardous materials, spent fuel is a hard, heavy ceramic 

material that is neither explosive nor volatile.5

 To achieve a wide dispersal, 

some portion of the spent fuel assemblies would have to be pulverized into 

small particles by an external force—such as a high-speed impact or a 

violent explosion—or some portion of the spent fuel assemblies would 

have to burn in a sustained, high-temperature fire. According to NRC, 

the redundancy and robustness of the designs of the fuel containers 

make wide dispersal highly unlikely. In the event of a dispersal, the most 

significant health effects would involve persons who inhaled very small 

(respirable) particles—10 microns or less in diameter.6

 Such particles 

would be absorbed into the body and possibly remain there for 

many years. In addition, these particles could be deposited on buildings 

and the ground where, in the absence of a costly cleanup effort, they could 

expose people to elevated levels of radiation. 

The transportation of spent fuel to Yucca Mountain—most likely by both 

truck and rail, but with a preference for using mostly rail—will be a major 

undertaking, spanning 20 to 30 years.7

 According to DOE, more than 

50,000 tons of the spent fuel have accumulated at 72 sites in 33 states, 

many located near urban areas in the Midwest and the East. DOE has 

estimated that the accumulated inventory will have grown to 69,000 tons 

by 2010 and that moving this volume could require approximately 

175 shipments per year over 24 years, relying on a combination of truck 

and rail shipments. 

For the transportation of spent fuel, NRC has certification and inspection 

requirements for shipping containers to ensure that the containers protect 

 5

 Spent fuel rods recently discharged from a reactor also contain some radioactive gases 

that are a by-product of the nuclear fission process—these gases account for a small 

fraction of the total quantity of radioactive material in spent fuel rods, but because of the 

short half lives of the material, the gases decay quickly and may not be present in older 

spent fuel. 

6

 A micron is one millionth of a meter in length—by comparison, one micron is about 

1/70 the thickness of a human hair. 

7

 At the present time, there is no direct rail service to Yucca Mountain and the closest rail 

line is 100 miles away. Until a branch rail line is established, intermodal transfer stations 

with interim storage may need to be established to transfer shipping containers from rail to 

truck for the final trip to Yucca Mountain. 
Page 8 GAO-03-426 Spent Nuclear Fuel 

against radioactive releases under accident scenarios. NRC has certified 

a number of shipping container designs for use on trucks and rail. The 

Nuclear Waste Policy Act of 1982, as amended, requires DOE to ship 

spent nuclear fuel and high-level radioactive waste to Yucca Mountain 

in containers that have been certified by NRC. The act also requires DOE 

to notify NRC in advance of spent fuel and high-level radioactive 

waste shipments. 

In addition to NRC, the Department of Transportation plays a role in 

regulating the transportation of spent fuel and other high-level waste. The 

department’s Research and Special Programs Administration sets certain 

safety standards for the transportation of hazardous materials, including 

spent fuel. These standards include, among other things, documentation 

and labeling of containers, including placards identifying the shipment, 

and requirements for separating certain radioactive materials while in 

transit. The Federal Motor Carrier Safety Administration oversees the 

safety of shipments by highway, and the Federal Railroad Administration 

oversees the safety of shipments by rail. The U.S. Coast Guard oversees 

the safety of shipments that may be made by barge. 

Studies conducted by NRC and DOE have consistently found that the 

likelihood of widespread harm to human health from a terrorist attack or 

a severe accident involving spent fuel is very low. None of the studies 

involving the transportation of spent fuel or dry storage of spent fuel 

identified a scenario resulting in widespread harm—largely because of 

the protective containers required by NRC. For example, these studies 

repeatedly found that transportation containers would be very difficult to 

penetrate, and in the worst-case scenarios where they may be penetrated, 

only a small fraction of the material would be released. Some studies 

involving spent fuel stored in pools of water found that widespread harm 

is possible under severe but unlikely accident conditions. Such conditions 

may include a catastrophic earthquake or a severe but unlikely accident 

that could uncover the fuel for several hours, possibly allowing it to 

spontaneously ignite and scatter radioactive material over a wide area. 

To respond to increased security concerns stemming from the 

September 11, 2001, terrorist attacks, NRC is further studying the safety 

and security of spent fuel in transit and in wet or dry storage, including 

the potential effects of more extreme attack scenarios such as deliberate 

aircraft crashes. 

Likelihood of 

Widespread Harm 

from Terrorist Attacks 

or Severe Accidents 

Involving Spent Fuel 

Is Low 
Page 9 GAO-03-426 Spent Nuclear Fuel 

Since the late 1970s, federal studies have examined the effects of both 

terrorist acts of sabotage and severe accidents involving shipping 

containers for spent fuel. Sabotage studies have sought to determine 

whether radioactive material could be released from shipping containers 

in specific sabotage scenarios, while accident studies have assessed 

whether radioactive material could be released in a variety of accidents, 

and the overall probability of their occurrence. Some of these studies were 

commissioned by NRC, and others by DOE, and many of them were 

conducted through DOE’s Sandia National Laboratory and other DOE 

laboratories. These studies collectively indicate that the construction of 

the shipping containers helps to limit releases.8

 Although NRC is confident 

in these results, it is sponsoring assessments to further validate computer 

models and address heightened security concerns. 

The most recent sabotage study—conducted by DOE’s Sandia National 

Laboratory for DOE in 1999—estimated the amounts and characteristics of 

releases of radioactive materials from truck and rail spent fuel containers 

subjected to two different types of weapons.9

 The results of this study 

confirmed the findings of earlier studies that armor-piercing weapons 

could penetrate shipping containers and release small quantities of 

radioactive material. The study found that, under a worst-case scenario, 

the weapon could penetrate a shipping container and release a small 

amount of material—equal to about 0.016 of 1 percent of the spent fuel in 

the container—as small, respirable particles. These small, respirable 

particles could become airborne and spread beyond the immediate vicinity 

of the attack.10

A subsequent DOE-sponsored report used the results of the 1999 Sandia 

National Laboratory study to estimate the human health impact of the 

 8

 See appendix I for a more detailed description of the NRC-certified spent fuel shipping 

containers. 

9

 Sandia National Laboratory, Projected Source Terms for Potential Sabotage Events 

Related to Spent Fuel Shipments, SAND 99-0963, a report prepared at the request of the 

Department of Energy, Albuquerque, N.Mex., June 1999. 

10 Rather than focus on the entire amount of material released, this and other studies 

focused on the amount of respirable particles—these particles can potentially become 

airborne, transported to densely populated areas, and inhaled. By comparison, the 

nonrespirable material would be a more localized problem that could be more easily 

contained and controlled. 

Shipping Containers 

Protect against 

Widespread Release 

of Fuel in Transit 

Sabotage Studies 
Page 10 GAO-03-426 Spent Nuclear Fuel 

most severe release.11 Using a computer-based analytic model and 

conservative assumptions, DOE’s contractor found that the predicted 

release from a truck container would cause about 48 cancer deaths over 

the long term and that a predicted release from a rail container would 

cause about 9 cancer deaths over the long term.12 DOE’s contractor’s 

analysis explained that these cancer deaths should be considered against 

a backdrop of an expected 1.1 million cancer deaths among the same 

population expected from other causes. This analysis assumed that the 

release would occur in an urban area with a population projected to the 

year 2035 under stable weather conditions. The analysis also assumed that 

the spent fuel release would contain twice the radioactive content of a 

typical spent fuel shipment and that there would be no evacuation or 

cleanup of the affected area for 1 year after the incident.13

These studies are the most recent in a series of studies dating back to 

the 1970s. According to NRC and DOE officials, confidence in the results 

of these studies has increased significantly as better data and more 

sophisticated analytic techniques have been used. Appendix II contains a 

fuller description of the methodology of these recent studies and the 

results of previous studies. 

Since the 1970s NRC has also sponsored a series of studies examining 

the risk that spent fuel could be released during transportation accidents. 

NRC’s most recent assessment of spent fuel transportation accident risks 

was conducted for NRC by Sandia National Laboratory and was published 

in 2000.14 The 2000 Sandia National Laboratory study, like preceding 

accident studies, found that an accidental release of spent fuel in transit 

is very unlikely and that significant human health impacts are even less 

likely. The study estimated that in over 99.9 percent of all truck and rail 

 11 Jason Technologies Corporation, Transportation Health and Safety 

Calculation/Analysis Documentation in Support of the Final EIS for the Yucca Mountain 

Repository, a report prepared at the request of the Department of Energy, Las Vegas, Nev., 

December 2001. 

12 The respirable particles include solid particles of spent fuel, radioactive gases released 

from the fuel rods, and particles of radioactive deposits that accumulate on the exterior of 

the fuel assemblies. 

13 Appendix II contains a summary of the methodology of both the 1999 Sandia National 

Laboratory study and the subsequent DOE analysis. 

14 U.S. Nuclear Regulatory Commission, Reexamination of Spent Fuel Shipment Risk 

Estimates, NUREG/CR-6672, Washington, D.C., March 2000. 

Accident Studies 
Page 11 GAO-03-426 Spent Nuclear Fuel 

accidents, the shipping container would experience no significant damage, 

and no radioactive material would be released. In fact, the analysis found 

that only 7 in 100,000 (0.007 of 1 percent) truck accidents and 4 in 100,000 

(0.004 of 1 percent) rail accidents would involve spent fuel casks in 

impacts or fires that might cause a release of radioactive material. While 

this study did not project the human health impacts of particular accident 

scenarios, it concluded that the overall risk of human exposure to 

accidental releases of spent fuel was far less than that estimated in the 

1977 study, which confirmed that NRC’s safety and security regulations 

then in place were adequate. 

A subsequent DOE-sponsored study used the results of the 2000 Sandia 

National Laboratory study to determine the potential health effects of the 

estimated quantity of material released.15 DOE’s contractor used the 

estimated amount of material released in what DOE determined as the 

most severe reasonably foreseeable accident to estimate the number of 

latent cancer fatalities that could result from severe accidents while 

shipping spent fuel to the Yucca Mountain repository.16 From this study, 

DOE concluded that this type of accident—having a probability of 

occurring about 2.8 times in 10 million accidents per year—could cause 

about 5 long-term latent cancer fatalities—far less than its estimate of 

48 latent cancer deaths in the event of a successful sabotage attack with 

armor-piercing weaponry. Apart from this type accident, DOE found that 

the probability of any deaths due to an accidental release of radiation was 

quite small. DOE’s final environmental impact statement for Yucca 

Mountain projected that accidents over 24 years of shipping would cause 

fewer than 0.001 latent cancer fatalities. In contrast, DOE projected that 

these same shipments had a much greater probability of resulting in 

deaths due to normal traffic accidents—between 2.3 and 4.9 traffic 

fatalities over the same 24-year period. 

As with the sabotage studies, these studies of accident scenarios are the 

most recent in a series of studies dating back to the 1970s. According to 

NRC and DOE officials, confidence in the results of these studies has 

 15 Jason Technologies Corporation, Transportation Health and Safety 

Calculation/Analysis Documentation in Support of the Final EIS for the Yucca Mountain 

Repository, a report prepared at the request of the Department of Energy, Las Vegas, Nev., 

December 2001. 

16 According to DOE, this accident involved a high-temperature, long duration fire that fully 

engulfed a rail container. 
Page 12 GAO-03-426 Spent Nuclear Fuel 

increased significantly as better data and more sophisticated analytic 

techniques have been used. Appendix II contains a fuller description of the 

methodology of these recent studies and the results of previous studies. 

Although NRC believes that the results of the federally sponsored studies 

are valid, it has several evaluations ongoing and planned to further assess 

its security and safety measures. To assess its existing security measures 

following the September 11, 2001, terrorist attacks, NRC initiated a 

commissionwide review. As part of this review, NRC commissioned 

Sandia National Laboratory to examine more severe terrorist attack 

scenarios involving spent fuel shipping containers. For example, the 

laboratory will assess the effects of (1) a 20-passenger aircraft loaded with 

explosives crashing into shipping containers and (2) a sustained attack on 

these containers using a variety of weapons in combination. 

As part of an ongoing process to assess its safety measures, NRC has a 

number of ongoing and planned studies. NRC commissioned Sandia 

National Laboratory for further validation of computer models used to 

evaluate the safety of shipping containers. To solicit comments on the 

scope of its evaluation, NRC held a series of public meetings beginning in 

1999. It considered comments obtained during these meetings and issued 

an interim report in 2002 that recommended several additional studies.17

Although these studies are still being designed, their preliminary 

objectives include (1) validating past computer-based predictions of 

damage to containers resulting from collisions, (2) validating past 

computer-based predictions of how well containers withstand fires, and 

(3) identifying the response of fuel pellets, fuel rods, and fuel assemblies in 

severe impacts. In contrast to past analyses of severe accident scenarios, 

the studies are to include physical tests of full-scale current model 

shipping containers. The results of these physical tests will be compared 

to the predictions of past computer-based analyses and serve to either 

validate or to correct those results. The studies are also to address some of 

the technical issues that were not adequately addressed by past accident 

analyses. For example, while past studies relied on expert judgment to 

assess the complex chain of variables involved in releasing respirable 

spent fuel from containers—including fracturing spent fuel rods and 

pellets—the planned studies will examine these events experimentally. 

 17 Sandia National Laboratory, Spent Nuclear Fuel Transportation Package Performance 

Study Issues Report, NUREG/CR-6768, a report prepared for the Nuclear Regulatory 

Commission, June 2002. 

Ongoing and Planned 

Assessments 
Page 13 GAO-03-426 Spent Nuclear Fuel 

According to NRC officials, the studies are expected to be completed 

by 2006. 

NRC studies have reported that a risk of widespread harm to human 

health from spent fuel arises from the remote possibility of a sustained 

loss of coolant in a spent fuel pool. Such a loss could potentially lead to a 

fire that would disperse radioactive material across a wide area. NRC’s 

most recent published study of this risk, released in 2001, found that, 

though the potential consequences of such a fire could be severe—nearly 

200 early fatalities and thousands of latent cancer fatalities—the likelihood 

of such a fire is low.18 The study estimated that a catastrophic earthquake 

or a severe but unlikely accident, such as dropping a 100- to 150-ton 

storage container into the pool, could precipitate a pool fire. 

The study was conducted to assess the risks associated with accidents 

at nuclear reactors that have been permanently shut down. According to 

NRC, once the fuel is removed from the reactors, there is a risk associated 

with the fuel stored in pools. NRC designed the study with conservative 

assumptions to identify the most severe possible impact on public health. 

The study assessed a variety of natural disasters and accidents that could 

drain coolant and cause a fire. These events included loss of electrical 

power, which would shut down the pool cooling system; an event that 

would significantly damage the pool cooling system; a drop of a heavy 

load, which could damage the pool wall or floor; a severe earthquake; 

and an accidental aircraft crash. The study found that a catastrophic 

earthquake and a heavy load drop were the events most likely to 

significantly damage the pool, leading to sustained loss of coolant and 

potentially causing a fire. 

The study then calculated the amount of radioactive material that might 

be released by a fire and the possible human health effects stemming from 

exposure to this material. In making these calculations, the study made 

various conservative assumptions to ensure that NRC identified the most 

severe consequences possible. For example, the study assumed that a pool 

fire would involve 100 percent of the spent fuel assemblies in the pool, 

releasing large amounts of radioactive material into the atmosphere. 

 18 U.S. Nuclear Regulatory Commission, Technical Study of Spent Fuel Pool Accident 

Risk at Decommissioning Nuclear Power Plants, NUREG-1738, Washington, D.C., 

February 2001. 

Widespread Release from 

Wet Storage Theoretically 

Possible but Unlikely 
Page 14 GAO-03-426 Spent Nuclear Fuel 

Two of the authors of the study noted that it was not certain how many 

spent fuel assemblies would actually burn in a fire. The uncertainty in 

the amount of radioactive material released depends on the fuel age and 

distribution in the pool and the characteristics of the accident scenario. 

The authors noted that some spent fuel assemblies might not reach the 

high temperatures required to burn and that some of the radioactive 

material might remain trapped in the pool or building. Because spent fuel 

decays and thus becomes less dangerous over time, the study evaluated 

scenarios in which the reactor had been shut down for 30 days, 90 days, 

1 year, 2 years, 5 years, and 10 years. For each scenario, the study 

evaluated two levels of radioactivity released from the fuel. NRC used the 

results of this study to calculate the potential health effects of a fire in a 

spent fuel pool. These results are shown in table 1. 

Table 1: Potential Health Effects of Fire in a Spent Fuel Pool 

Lower level of radioactivitya Higher level of radioactivitya

Time after 

shutdown of reactor 

 Number of early 

fatalities

Number of latent 

cancer fatalities 

Number of early 

fatalities 

Number of latent 

cancer fatalities

30 days 2 3,500 200 15,000

1 year 1 b 80 b 

5 years 0 b 1 b 

10 years 0 b 0 7,500

Source: NRC. 

a

NRC assumed a low level and a high level of ruthenium in the dispersed spent fuel. Ruthenium, 

found in higher levels in recently discharged fuel, is a particularly lethal isotope when dispersed in 

small particles. 

b

Information not available. 

The study noted that the results are based on a natural disaster or an 

accident severe enough to lead to a pool fire and that the risk of such an 

event occurring is very low. NRC also noted that part of the reason for 

the low probability is NRC’s defense-in-depth policy, which states that 

NRC establishes requirements to ensure that safety will not be wholly 

dependent on any single system. Instead, NRC’s requirements ensure 

multiple or redundant safety systems. In the case of the storage pool 

studied in the 2001 report, NRC noted that several factors combine to 

make a pool fire unlikely, including the robust design of the pool; the 

simple nature of the pool support systems; and the long time required to 

heat up the fuel, which allows time for operators to respond.19 For 

 19 See appendix I for a description of the NRC-certified wet storage pools. 
Page 15 GAO-03-426 Spent Nuclear Fuel 

example, according to the 2001 report, heating the least-decayed spent fuel 

to the ignition point—were it to occur at all—would take hours, perhaps 

even days. Thus, NRC officials explained that even if a massive loss of 

coolant occurred, plant operators might still have time to react, depending 

on the extent of the damage. NRC requires that nuclear power plants have 

a backup water supply that can cool fuel in case of an accident, so, 

depending on the extent of damage, plant operators might be able to keep 

the fuel submerged. 

The risk of a pool fire is also limited by the ability of some of the fuel to 

be cooled by simple air ventilation if the coolant drains out. According to 

NRC, completely draining a pool may allow enough air ventilation among 

the stored fuel assemblies so that the spent fuel would stay below the 

ignition point of a self-sustaining fire (about 1,650 degrees Fahrenheit). 

Furthermore, even if a fire did begin in one assembly, there is considerable 

uncertainty about whether the fire would spread to other assemblies. A 

1987 study of spent fuel pools found that spent fuel in pools with fewer 

assemblies, after being cooled for just a few weeks, would not ignite if 

subjected to loss of coolant.20 Under the dense storage conditions 

characterized by most spent fuel pools today, however, air ventilation 

becomes less effective. 

To begin addressing some of the uncertainties regarding the risks of 

storing spent fuel in wet storage pools, NRC has some ongoing work, and 

recently completed some initial evaluations of sabotage attacks on these 

pools, and has more work planned and ongoing at two DOE national 

laboratories. Following the terrorist attacks of September 11, 2001, NRC 

commissioned the U.S. Army Corps of Engineers to examine potential 

effects of sabotage directed at spent fuel pools. The Corps conducted 

several computer-based analyses of the potential effects of armor-piercing 

weapons and high explosives on typical spent fuel pools. The analyses 

found that the penetration of armor-piercing weapons and high explosives 

could vary considerably, depending, among other things, on the size of the 

weapon or explosive and the sophistication of the attacker. 

NRC is also conducting studies with less conservative assumptions to 

more realistically evaluate the risks of spent fuel in a drained pool. NRC 

 20 Brookhaven National Laboratory, Severe Accidents in Spent Fuel Pools in Support 

of Generic Safety Issue 82, NUREG/CR-4982, a report prepared for the U.S. Nuclear 

Regulatory Commission, July 1987. 

NRC Continues to Study the 

Risks of Storing Spent Fuel 

in Pools 
Page 16 GAO-03-426 Spent Nuclear Fuel 

has contracted with Argonne National Laboratory to study the conditions 

necessary to ignite a pool fire. NRC has also contracted with Sandia 

National Laboratory for a series of studies to define potential threats, and 

to identify potential vulnerabilities, regulatory improvements or legislative 

initiatives to improve security and safety and better protect public health. 

The studies by Sandia National Laboratory include a review of a variety of 

terrorist scenarios, including attacks on fuel pools with aircraft and high 

explosives. According to NRC, preliminary results of these studies indicate 

that spent fuel may be more easily cooled than has been predicted in some 

past studies and that off-site radiological releases may be substantially 

reduced from previous worst-case estimates. Predicted public health 

effects might also be substantially reduced for the worst scenarios where 

coolant is lost and recovery actions are not successful in cooling the fuel. 

Dry storage containers, like shipping containers, pose a considerable 

barrier to releasing spent fuel. Used to store spent fuel when it is removed 

from wet storage, dry storage containers are constructed of layers of steel 

and radiation barriers such as concrete.21 In establishing regulations for 

dry storage of spent fuel, NRC stated in 1998 that dry storage containers 

are structurally similar to shipping containers and that the results of 

sabotage studies on shipping containers could reasonably be applied to 

dry storage containers. Nevertheless, NRC is continuing to study potential 

risks of releases from dry storage containers. 

Studies by DOE and the Corps on dry storage containers have generally 

reached the same conclusion—that the thick walls of the containers, 

consisting of an inner steel container and an outer steel or concrete 

container, could not be penetrated by airplane crashes and would result in 

no significant release of radiation when attacked with advanced weapons. 

Two DOE-sponsored reports, released in 1998 and 2001, found that 

airplane crashes would not penetrate dry storage containers.22 The reports 

focused on the most penetrating components of the commercial jet 

aircraft: the engines and landing gear. Both reports concluded that 

 21 See appendix I for a description of the of the NRC-certified dry storage containers. 

22 Jason Technologies Corporation and Pacific Northwest National Laboratory, Accident 

Analysis for Continued Storage, a report prepared for the U.S. Department of Energy, 

October 27, 1998. Jason Technologies Corporation, An Evaluation of the Consequences of 

a Commercial Aircraft Crash into the Yucca Mountain Repository, a report prepared for 

the U.S. Department of Energy, December 2001. 

Dry Storage Containers 

Safeguard against 

Widespread Release 
Page 17 GAO-03-426 Spent Nuclear Fuel 

although airplane crashes could damage the containers, no radioactive 

material would be released. The analysis showed that the containers 

would break up the airplane, spreading jet fuel over a wide area, 

causing the jet fuel to dissipate or burn without affecting the spent fuel 

in the containers. 

Two other studies, performed in 2001 by the Corps, found that the 

containers would not release significant amounts of radioactive 

material when attacked by armor-piercing weapons or high explosives. 

The study examining the effect of armor-piercing weapons found that the 

penetration to the containers was very limited. NRC and DOE officials and 

independent experts told us that, based on a previous analysis and similar 

studies involving shipping containers, the weapons would not likely cause 

a significant release. The study examining the effects of high explosives 

found that the explosives would not completely penetrate the container. 

The study showed extensive exterior damage, but no penetration to the 

spent fuel. 

NRC is continuing to study potential risks to dry storage. NRC has 

contracted with Sandia National Laboratory to assess the vulnerability of 

dry storage containers to terrorist attacks, including a further analysis 

of aircraft crashes and the effects of high explosives. In addition, the 

laboratory will investigate measures to mitigate any vulnerability identified 

through the assessment. 

As DOE develops its plans for shipping spent fuel to the Yucca Mountain 

repository, the agency has several potential options for enhancing the 

security of spent fuel during the Yucca Mountain shipping campaign. 

Specifically, DOE could potentially minimize its total number of spent 

fuel shipments, ship the fuel in an order that reduces risk, or transport the 

fuel on railroad trains dedicated exclusively to hauling spent fuel. Not all 

of these options may be feasible under the terms of DOE’s contracts with 

spent fuel owners, and some options for shipping in a particular order 

would conflict with one another. 

DOE could enhance the overall security of spent fuel by minimizing the 

total number of shipments. Fewer shipments would present fewer 

potential targets for terrorists and could also enhance safety because there 

would be fewer chances for an accident. Representatives of the nuclear 

power industry and nuclear safety experts that we contacted agreed on 

these points. For example, a representative of a consortium of nuclear 

utilities told us that shipping spent fuel by rail is preferable to shipment 

NRC Continues to Study Risks 

to Dry Storage Containers 

Options May Exist to 

Further Enhance 

Security and Safety 

Minimizing Number of 

Shipments 
Page 18 GAO-03-426 Spent Nuclear Fuel 

by truck because spent fuel containers designed for rail can carry about 

5 times more spent fuel than truck containers. This larger capacity 

translates to fewer shipments overall. Similarly, a frequent critic of the 

safety of spent fuel shipments agreed that fewer shipments would be 

better, noting that fewer, large shipments are easier to protect and track. 

Beyond expressing a preference for shipping spent fuel to Yucca Mountain 

mostly by rail, DOE has not yet developed its plans to implement the 

shipping campaign. 

In addition to providing security advantages, minimizing the number 

of shipments by using rail provides safety and efficiency benefits. 

According to a 1998 Department of Transportation report, rail was the 

safer mode for shipping large amounts of spent fuel.23 The report states 

that minimizing trips usually reduces total risk by reducing risks 

associated with routine radiation exposure—such as the incidental 

exposure experienced by transportation and plant workers while shipping 

containers are being prepared—as well as accident-related exposure and 

other nonradiation accident consequences. 

DOE’s ability to minimize the total number of shipments may be limited 

by its contracts with owners of spent fuel. Under the contracts, DOE is to 

establish a shipping queue, in which each utility has shipping rights based 

on the date and quantity of fuel removed from a reactor. In many cases, 

the places in the queue correspond to quantities of spent fuel that would 

fill less than three large rail containers—an amount that, according to the 

Association of American Railroads, would be a reasonable size for a 

single rail shipment. If strictly followed, the queue could result in many 

more shipments than necessary. For example, the 12 spent fuel owners 

with the largest quantities of spent fuel would make approximately 

576 shipments based on the shipping queue.24 On the other hand, if these 

12 owners consolidated all their shipments into rail containers and used 

3 containers per shipment, they could reduce their total shipments to 479, 

a 17 percent reduction. If these same owners consolidated shipments 

into 5 rail containers per shipment, which according to DOE is another 

 23 Identification of Factors for Selecting Modes and Routes for Shipping High-Level 

Radioactive Waste and Spent Nuclear Fuel, U.S. Department of Transportation, Research 

and Special Programs Administration, April 1998. 

24 These figures are based on our analysis of DOE’s 1995 Acceptance Priority Ranking 

(U.S. DOE Office of Civilian Radioactive Waste Management), the most recent version 

published. 
Page 19 GAO-03-426 Spent Nuclear Fuel 

possible option, total shipments could be reduced to 287—a nearly 

50 percent reduction. 

DOE could also enhance security by shipping spent fuel in an order 

that minimizes risk. There are at least three shipping orders that would 

potentially reduce risk: (1) shipping fuel from shutdown nuclear reactors 

first, reducing the number of sites storing spent fuel; (2) shipping the 

oldest and least radiologically dangerous fuel first to reduce transportation 

risk; or (3) shipping fuel from storage pools first, reducing the likelihood 

of a pool fire. Shipping fuel first from shutdown nuclear reactors would be 

permissible under DOE’s contracts with fuel owners, but the contracts 

might preclude the other two options. Further, to some extent, these 

options conflict with one another. For example, an emphasis on shipping 

fuel from spent fuel pools first could leave some older fuel in dry storage 

at current storage facilities. Data are not available to determine which 

order would provide the greatest risk reduction. 

DOE could potentially enhance the overall security of spent fuel by 

first shipping fuel currently stored at shutdown nuclear reactor sites. 

Currently, about 4,100 tons of spent fuel—about 8 percent of the total 

stored nationwide—are stored at 14 shutdown nuclear reactors.25 Because 

nine of these sites will not be accumulating additional spent fuel, clearing 

their spent fuel inventory would eliminate them as potential targets of a 

terrorist attack.26

DOE recognized the potential importance of removing spent fuel from 

shutdown reactors when it established its contracts for disposal of spent 

fuel. Although the contracts establish a shipping queue, the contracts 

allow DOE to override the queue to make an exception for spent fuel 

from shutdown reactors. Specifically, the contracts provide that, 

notwithstanding the age of spent fuel, priority may be accorded any spent 

fuel removed from a civilian nuclear power reactor that has reached the 

end of its useful life or has been shut down for whatever reason. 

 25 In addition to permanently shutdown reactor sites, a limited quantity of spent fuel is 

stored at an independent storage facility in Morris, Illinois. 

26 Four of the shutdown reactors are co-located with operating reactors. 

Order in Which Spent 

Fuel Is Shipped Could 

Enhance Security 

Shipping Fuel from Shutdown 

Reactor Sites First 
Page 20 GAO-03-426 Spent Nuclear Fuel 

DOE could lower the risk of transporting spent fuel by shipping the 

oldest spent fuel first. Radioactivity emitted by some components of spent 

fuel declines significantly over comparatively short periods of time.27 For 

example, one of the more radioactive elements in spent fuel—cobalt60—

accounts for about 90 percent of the gamma radiation emitted by spent 

fuel when it is first removed from the reactor.28 However, after about 

25 years, cobalt60 emits about 3 percent of the gamma radiation it did when 

first removed from the reactor. Similarly, the radioactivity of cesium137, a 

comparatively volatile element that would be a major component of any 

accidental or deliberate release, declines by half after 30 years. Shipping 

older spent fuel first could therefore be preferable in the event of a 

deliberate or accidental release during transit. For example, a release of 

spent fuel that is 25 or 30 years old would be a lesser—though still 

significant—threat to public health than fuel that is only 5 or 10 years old. 

Analyses performed for DOE’s environmental impact statement for the 

Yucca Mountain repository illustrate the reduced impact that a release 

of older spent fuel can have on public health. In the draft environmental 

impact statement, DOE estimated that a particular release due to a 

sabotage attack could result in about 16 latent cancer fatalities. This 

scenario assumed that the shipped fuel was about 23 years old, which is 

approximately the average age of the inventory of spent fuel. The final 

environmental impact statement analyzed the same scenario, except that it 

assumed that the shipped fuel was about 15 years old. This analysis found 

that such a release would cause about 48 latent cancer deaths—3 times as 

many as the older fuel. The age of the fuel was one of two major factors 

that resulted in the higher estimate of latent cancer fatalities in the final 

statement. DOE noted that the younger, more dangerous fuel, such as 

spent fuel discharged 5 years or less from a reactor, makes up a small 

percentage of the total inventory of spent fuel. As a result, the youngest, 

hottest fuel would be less likely to be shipped or would represent a small 

fraction of the fuel that is shipped. 

In discussions on security and safety issues surrounding the proposed 

shipment of fuel to Yucca Mountain, some state and industry 

representatives that we contacted also acknowledged the benefits of 

 27 Some components of spent fuel remain deadly for thousands or millions of years. For 

example, uranium235 requires about 704 million years for its radiation output to be cut 

in half. 

28 As mentioned previously, gamma radiation can damage critical organs of the body. 

Shipping Oldest Fuel First 
Page 21 GAO-03-426 Spent Nuclear Fuel 

shipping older spent fuel first. An analyst under contract with the state 

of Nevada noted that shipping the oldest fuel first would be the most 

important factor in protecting public health during transit. Not only would 

older fuel have lower consequences if released in an accident or a terrorist 

event, but it also would be safer for transportation workers—drivers and 

handlers at intermodal transfer points—and the general public. A 

representative of the National Research Council’s Board on Radioactive 

Waste Management told us that shipping the oldest fuel first would help 

minimize potential human health consequences in the event of a release 

during transit. However, this representative said that if one assumes that 

the robust shipping containers make a release unlikely, the potential risk 

reduction associated with the age of the fuel becomes less important. 

Regardless of the potential transportation-related security benefits, DOE’s 

contracts with spent fuel owners limit its ability to ship the oldest fuel 

first. In addition to establishing a shipping queue, the contracts allow each 

fuel owner discretion to decide which of its spent fuel is actually delivered 

to DOE, commensurate with the quantity of fuel associated with a 

particular spot in the queue. For example, the Exelon company—the 

nation’s largest nuclear power company—has a place in the queue for 

about 35 tons of spent fuel removed from a reactor located at its plant in 

Zion, Illinois. When the time comes to ship this fuel to the repository, 

Exelon may deliver either this fuel or an equal quantity of fuel—possibly 

much younger and more radioactive fuel—from any of its facilities located 

at sites in Illinois and sites in Pennsylvania and New Jersey. 

Because owners have discretion to choose which fuel they will actually 

ship under the terms of the contract, DOE does not have the ability under 

the contract to require that oldest fuel be shipped first. Fuel owners will 

likely select spent fuel for shipment based on their operational needs. For 

example, representatives of Progress Energy, a fuel owner with reactors in 

the Southeast, said they would will likely ship from their pools first 

because their pools are reaching capacity. Similarly, an Exelon official 

said that shipping from pools first would minimize the need for dry 

storage facilities. 

As discussed in the first section of this report, a fire in a wet storage pool, 

while highly unlikely, is theoretically possible. Shipping spent fuel from 

densely packed spent fuel pools first could have security benefits. 

Because DOE has not yet opened a permanent repository, spent fuel has 

accumulated in quantities that pools were not originally designed to 

contain. NRC officials noted that while a few spent fuel pools have low 

density in at least part of the pools, nearly all pools are densely packed. 

Shipping Fuel from Densely 

Packed Pools First 
Page 22 GAO-03-426 Spent Nuclear Fuel 

These densely packed pools contain as much as 3.5 times more spent 

fuel on average than the pools were originally designed to store. Reducing 

the density of spent fuel in the pools would reduce the likelihood of a 

fire. Recent NRC and independent studies show that lower-density 

configurations allow for greater spacing between assemblies, which allows 

air to more efficiently circulate in the event of coolant loss. According 

to these reports, greater spacing could also help prevent a fire from 

spreading among assemblies. Also, in the unlikely event of a fire, fewer 

assemblies in the pool could result in reduced consequences. 

As noted earlier, DOE’s contracts limit its ability to influence the order in 

which spent fuel is shipped. Some owners may prefer to ship fuel from 

densely packed pools first because when the pools reach full capacity, the 

fuel must be removed or the plant must shut down. To the extent that, as 

Exelon and Progress Energy officials stated, utilities are likely to ship from 

their wet pools first, the threat would be reduced earliest at these pools. 

This would, however, result in a relatively higher threat during transport 

from relatively younger, more radioactive, spent fuel. It is not clear 

whether this will be a common preference. 

According to some analysts, DOE could enhance the security of spent 

fuel shipments by using trains dedicated to carrying only spent fuel. 

Such trains would typically consist of three to five rail cars, carrying one 

container of spent fuel per car. A truck shipment can carry 1 to 2 tons of 

spent fuel. In contrast, depending on the containers used, a 3-car train can 

carry from 50 to 65 tons of spent fuel and a 5-car train can carry from 

about 80 to 110 tons of spent fuel. Although dedicated trains could 

enhance the security and safety of spent fuel shipments, these benefits 

would have to be weighed against potential drawbacks. The benefits 

would also have to be weighed against constructing a rail line to Yucca 

Mountain. Currently, no rail line extends to Yucca Mountain. 

Advocates of dedicated trains told us that such trains offer two primary 

security and safety advantages. First, the use of dedicated trains would 

significantly reduce the exposure of spent fuel shipments to a terrorist 

attack by significantly shortening the trip duration from its point of origin 

to the repository. A representative of the Association of American 

Railroads, which recommended that DOE use dedicated trains for the 

shipment of spent fuel, explained that a spent fuel shipment from the East 

Coast to Nevada would take about 3 to 4 days by dedicated rail, while the 

same trip by regular rail would take about 8 to 10 days. Specifically, spent 

fuel transported by regular rail would spend significant amounts of time in 

Shipping Fuel on Trains 

That Haul Only Spent Fuel 
Page 23 GAO-03-426 Spent Nuclear Fuel 

rail yards where trains are broken up and reconfigured. While in the rail 

yards, spent fuel containers could be stationary targets. 

Second, using dedicated trains would ensure that spent fuel was not 

shipped with flammable hazardous materials. If spent fuel were released 

from its containers in an accident or a terrorist attack, a fire fueled by 

flammable materials could spread radioactive material over a wide area. 

For example, NRC recently issued an analysis regarding a rail tunnel 

fire that occurred in Baltimore in July 2001 that involved more than 

28,000 gallons of a flammable solvent. NRC estimated that temperatures as 

high as 1,800 degrees Fahrenheit were reached at certain locations in the 

tunnel during the course of the fire but found that temperatures averaged 

900 degrees in other parts of the fire. NRC studied the potential effects of 

this fire on a spent fuel transportation container carrying spent fuel and 

concluded that, when subjected to similar fire conditions, the container 

would not release radioactive material.29

According to transportation officials we spoke to, dedicated trains can 

also have safety and other benefits beyond sabotage prevention. For 

example, officials of the Union Pacific Railroad and the Association of 

American Railroads said that combining cars carrying fully loaded spent 

fuel containers on trains with those carrying other cargo raises operational 

and safety issues. Rail cars carrying spent fuel rail containers are 

extraordinarily heavy—such a car weighs about 470,000 pounds compared 

to about 200,000 pounds for a standard loaded rail car. This weight 

differential introduces difficulties in the physical dynamics of a train 

carrying spent fuel and other cargo, making derailments more likely. 

On the other hand, it is not clear that the advantages of dedicated trains 

outweigh the additional costs. In 1980, while considering amendments to 

its security regulations, NRC examined the case for requiring dedicated 

trains for rail shipments of spent fuel. NRC noted the advantages of 

dedicated trains but also noted that dedicated trains are no more capable 

of avoiding high-population areas than are regular trains, that a regular 

train in a rail yard would be under surveillance by escorts and railroad 

police, and that the necessary physical protection measures can be as 

easily implemented on regular trains as on dedicated trains. For these and 

other considerations, NRC declined to require dedicated trains. Further, 

 29 Evaluation of the Effects of the Baltimore Tunnel Fire on Rail Transportation of 

Nuclear Fuel. Nuclear Regulatory Commission, January 6, 2003. 
Page 24 GAO-03-426 Spent Nuclear Fuel 

although DOE recognized the possible advantages of shipping spent 

nuclear fuel by dedicated trains, DOE also concluded in its final 

environmental impact statement that available information does not 

indicate a clear advantage for the use of either dedicated trains or general 

freight service. 

The events of September 11, 2001, elevated lingering public concerns 

about the security of spent fuel, and in particular the security and safety 

of large-scale shipping of spent fuel. NRC and DOE studies show a low 

likelihood of widespread harm to human health from terrorist attacks or 

severe accidents involving spent fuel. Nonetheless, DOE could potentially 

take a number of measures to further enhance the security and safety of 

the shipping campaign to Yucca Mountain. It is not clear whether the 

additional security and safety benefits such measures offer are worth 

the additional costs and effort—possibly including a renegotiation of 

contracts that DOE has established with the nation’s utilities—that they 

would entail. In addition, it is not clear which of these measures—some of 

which conflict with each other—would provide the greatest safety and 

security benefit. However, we believe they should be explored. 

To ensure that all reasonable options to further enhance the security and 

safety of spent fuel in storage at nuclear power plants and in transit are 

explored, we recommend that the Secretary of Energy assess the potential 

benefits and costs of (1) minimizing the total number of shipments of 

spent fuel by consolidating shipments where possible, (2) shipping spent 

fuel in an order that further minimizes risk, and (3) emphasizing the use of 

trains dedicated to hauling spent fuel. 

We provided DOE and NRC with drafts of this report for review and 

comment. DOE generally concurred with the facts of the report, noting 

that the information on transit was accurate and well balanced. DOE also 

concurred with our recommendations, with one exception. DOE noted 

that the Department of Transportation was expected to release a study 

later this year on the safety and security implications of transporting spent 

fuel by dedicated train. DOE stated that it preferred to wait for the 

outcome of the study before beginning its own review. DOE also provided 

technical comments, which we incorporated into the report. 

NRC also generally concurred with the facts of the report, noting that 

the information provides a reasonable characterization of the current 

understanding of risks associated with spent fuel storage. However, NRC 

Conclusions 

Recommendations for 

Executive Action 

Agency Comments 

and Our Evaluation 
Page 25 GAO-03-426 Spent Nuclear Fuel 

stated that it does not consider the results of its most recently published 

studies on spent fuel in a pool and spent fuel in transit, as quoted in the 

report, to accurately reflect the consequences of a potential terrorist 

attack. Rather, NRC indicated that the studies started with overly 

conservative assumptions, resulting in “unrealistically conservative” 

results. NRC noted that it is currently conducting studies to assess the 

potential consequences of a terrorist attack that use more realistic 

assumptions. NRC also noted in its technical comments that preliminary 

results from these ongoing studies show that potential consequences may 

be far less severe than reported in the current publications. 

We revised our report to account for NRC’s preliminary findings from 

ongoing work involving the risk associated with spent fuel pools. As our 

report states, these findings indicate that risks from spent fuel pools 

may be substantially reduced from previous estimates. We used NRC’s 

February 2001 report, Technical Study of Spent Fuel Pool Accident Risk 

at Decommissioning Nuclear Power Plants, with the understanding that 

the report received a high level of scrutiny both within and outside NRC 

prior to its publication. As stated in the report, “Preliminary drafts of this 

study were issued for public comments and technical reviews in June 1999 

and February 2000. Comments from interested stakeholders, the Advisory 

Committee on Reactor Safeguards, and other technical reviewers have 

been taken into account in preparing this study. A broad quality review 

was also carried out at the Idaho National Engineering and Environment 

Laboratory, and a panel of human reliability analysis experts evaluated the 

report’s assumptions, methods, and modeling.” The report also states that, 

based on the comments received, “staff did further analyses and also 

added sensitivity studies on evacuation timing to assess the risk 

significance of relaxed offsite emergency preparedness requirements 

during decommissioning.” Given this level of review, we believe it to be 

appropriate to report the results of this study. 

NRC also took issue with our use of its report, Reexamination of Spent 

Fuel Shipment Risk Estimates. NRC explained that the analyses in this 

document are similarly overly conservative. This March 2000 study was 

conducted by Sandia National Laboratory at the request of NRC to 

reexamine the conclusions reached in previous studies regarding the risks 

of spent fuel shipments. As with its February 2001 report, this report also 

indicated a high level of review prior to publication. Specifically, the 

report mentions a number of individuals who provided comments to the 

report, including staff at Sandia National Laboratory, Lawrence Livermore 

National Laboratory, and “a number of technical experts at the NRC.” 
Page 26 GAO-03-426 Spent Nuclear Fuel 

Given the intent of this study and its level of review, we believe it to also 

be appropriate to report the results of this study. 

We performed our review at DOE and NRC headquarters in Washington, 

D.C., at NRC’s Region III office near Chicago, Illinois, and at DOE’s Yucca 

Mountain Project office in Las Vegas, Nevada. We visited several sites 

where spent fuel is stored, including operating nuclear power plants, a 

decommissioned nuclear power plant, and independent spent fuel 

storage sites. We conducted our review from April 2002 to June 2003 in 

accordance with generally accepted government auditing standards. 

To determine the potential health effects of a terrorist attack or a severe 

accident involving commercial spent nuclear fuel, we examined a variety 

of federally sponsored studies, primarily conducted or sponsored by DOE 

and NRC. We examined critiques of these studies prepared by a variety of 

groups and individuals. We also spoke to many of the authors of these 

federal studies, authors of critiques of these studies, nuclear energy 

representatives, and other individuals representing a variety of 

backgrounds, including academia and special interest groups. 

To identify options for DOE to enhance the security of spent fuel as it 

develops its plans to ship the fuel to Yucca Mountain, we reviewed 

documents analyzing DOE’s plans and preferred alternatives, including the 

environmental impact statement and many of its supporting documents. 

We also interviewed DOE, NRC, and Department of Transportation 

officials responsible for developing and coordinating safe shipments of 

spent nuclear fuel. We also spoke to state and local government officials in 

a number states, including Nevada; nuclear energy representatives; and a 

variety of groups and individuals representing a spectrum of viewpoints on 

the shipment of spent nuclear fuel. 

As agreed with your office, unless you publicly announce the contents 

of this report earlier, we plan no further distribution of it until 30 days 

from the date of this letter. At that time, we will send copies of this report 

to other interested parties and make copies available to others who 

request them. In addition, the report will be available at no charge on 

GAO’s Web site at http://www.gao.gov/. 

Scope and 

Methodology 
Page 27 GAO-03-426 Spent Nuclear Fuel 

If you or your staff have any questions about this report, please call me at 

(202) 512-3841. Key contributors to this report are listed in appendix V. 

Sincerely yours, 

Robin M. Nazzaro 

Director, Natural Resources 

 and Environment 
Appendix I: Nuclear Regulatory Commission 

Requirements for Safety and Security of 

Spent Fuel 

Page 28 GAO-03-426 Spent Nuclear Fuel 

As the regulating agency responsible for spent fuel, the Nuclear Regulatory 

Commission (NRC) must adequately protect the public health and safety 

against accidents or acts of sabotage. To provide this assurance, NRC uses 

a “defense-in-depth” philosophy. Consistent with this philosophy, NRC 

designs its safety and security requirements to ensure that public safety 

and health are not wholly dependent on any single element of the design, 

construction, maintenance, or operation of a nuclear facility. More 

specifically, NRC designs multiple or redundant measures to mitigate 

areas of known risk or to increase confidence in areas of uncertainty. 

Listed below are some of the primary requirements NRC has recognized as 

protecting spent fuel while in transit, in wet storage, and in dry storage. 

NRC requires that transporters of spent fuel (1) contain the fuel in 

NRC-certified shipping containers that must meet stringent durability 

performance requirements and (2) comply with requirements designed 

to impede an act of sabotage on the fuel. 

NRC regulations for spent fuel shipping containers dictate that the 

containers prevent releases of significant amounts of radiation under both 

normal operating conditions and in hypothetical accident scenarios. The 

containers include shielding to ensure that persons near a container are 

not exposed to significant amounts of radiation. In addition, the containers 

must remain intact after a series of simulated accident conditions, 

including 

• an impact test, in which containers are dropped from 30 feet onto a flat, 

unyielding surface; 

• a puncture test, in which containers are dropped from 40 inches onto a 

6-inch diameter steel bar at least 8 inches long; 

• a fire test, in which containers are engulfed in a 1,475-degree Fahrenheit 

fire for 30 minutes; and 

• an immersion test in which containers are submerged in 3 feet of water for 

8 hours. 

The containers must survive each of these tests in succession, without 

significant levels of surface radiation or release of spent fuel. Containers 

must also be shown to survive water pressure equivalent to immersion 

under nearly 670 feet of water for 1 hour. 

Because of these requirements and the dimensions of the spent fuel 

assemblies they contain, spent fuel shipping containers are massive and 

robust. A typical train container is about 25 feet long and 11 feet in 

Appendix I: Nuclear Regulatory Commission 

Requirements for Safety and Security of 

Spent Fuel 

Requirements for 

Preventing Release of 

Spent Fuel in Transit 
Appendix I: Nuclear Regulatory Commission 

Requirements for Safety and Security of 

Spent Fuel 

Page 29 GAO-03-426 Spent Nuclear Fuel 

diameter, weighs about 100 tons empty, and about 120 tons fully loaded—

thus the container can account for over 80 percent of the total weight of a 

shipment. Though truck containers have significantly less capacity than 

rail containers, both types have similar basic designs. As figure 2 indicates, 

they are generally composed of several layers of shielding material, 

totaling about 5 to 15 inches in thickness, including a radiation barrier 

consisting of lead or depleted uranium. 

Figure 2: Cutaway Graphic of a Spent Fuel Truck Transportation Cask 
Appendix I: Nuclear Regulatory Commission 

Requirements for Safety and Security of 

Spent Fuel 

Page 30 GAO-03-426 Spent Nuclear Fuel 

When in transit, each end of the container is made of material that is 

designed to absorb much of the force of an impact. Figures 3 and 4 show a 

spent fuel rail container and a truck container, respectively. 

Figure 3: Spent Fuel Rail Container 

Figure 4: Spent Fuel Truck Container on a Trailer 
Appendix I: Nuclear Regulatory Commission 

Requirements for Safety and Security of 

Spent Fuel 

Page 31 GAO-03-426 Spent Nuclear Fuel 

Although the shipping container is the most important component in 

preventing release and dispersal of spent fuel in transit, NRC also requires 

transporters of the spent fuel to implement measures designed to further 

protect spent fuel shipments from sabotage. For example, transporters 

of spent fuel must ensure that shipments are under surveillance, that 

arrangements have been made with local law enforcement agencies for 

their response in the event of an emergency, and that rail and highway 

routes have been approved by NRC. NRC had also required that armed 

escorts be either aboard the shipping vehicle or in a following vehicle in 

areas of high population; NRC has since strengthened the security required 

of shipments following the September 11, 2001, terrorist attacks. 

Spent fuel pool designs must meet specific performance criteria before 

NRC can issue a license for construction or operation. The requirements 

focus on ensuring that the safety features of the pool survive certain 

natural phenomena or accidents to ensure that, among other things, the 

pool will retain water and keep the stored fuel sufficiently cool. Spent fuel 

in wet storage is also protected by the physical security measures in place 

at the storage site. 

As part of the licensing process prior to construction and operation, 

utilities must submit reports that analyze the likelihood of certain natural 

phenomena, such as earthquakes, hurricanes, floods, and tidal waves. 

Using probability analyses, historical information, and current information 

on seismology, geology, meteorology, and hydrology, the utilities must 

determine the risks of certain types of natural phenomena. Then the 

utilities must show that the proposed pool designs would survive the most 

severe natural phenomena or combinations of less severe phenomena 

expected for that particular area. The utilities must also perform the same 

exercise for the likelihood and severity of certain accidents, including 

airplane crashes. For example, pools constructed near airports may have 

to be designed to withstand certain types of accidental airplane crashes. 

Consequently, although the specific designs of wet storage pools vary 

from site to site, they are massive, robust structures. Pools are typically 

30 to 60 feet long, 20 to 40 feet wide, and 40 feet deep. Pools could nearly 

hold three semi-truck tractor-trailers parked side-by-side and stacked 

three deep. The pool is contained by a structure consisting of a 1/8 inch to 

1/4 inch stainless steel liner, and 4- to 6-foot thick walls of steel-reinforced 

concrete. Generally, the pools are contained in other buildings. The roofs 

of some of these buildings may be made from industrial-type corrugated 

steel. The assemblies, stored vertically in racks, must be immersed at least 

Requirements for 

Preventing Release of 

Spent Fuel in Wet Storage 
Appendix I: Nuclear Regulatory Commission 

Requirements for Safety and Security of 

Spent Fuel 

Page 32 GAO-03-426 Spent Nuclear Fuel 

20 feet below the surface of the water in order to keep the fuel cool and to 

provide a sufficient radiation barrier. See figure 5 for a photograph of a 

wet storage pool. 

Figure 5: A Wet Storage Pool 

Spent fuel pools are also protected by the physical security measures in 

place at the facilities where they are located. About 95 percent of the spent 

fuel inventory is stored in pools, most of which are located at operating 

nuclear reactors. The perimeters of these reactor sites are secured by 

fences topped with barbed wire, vehicle barriers, and intrusion detection 

systems—including perimeter cameras and motion detection technology—

that are monitored 24 hours per day. Access to the building containing the 

wet storage pools is impeded by locked steel doors capable of surviving 

armed assault and security checkpoints where a person’s identity must be 

verified and where security searches take place. Finally, these facilities are 

manned by a force of armed guards. 

In addition, nuclear power plants are required to coordinate an emergency 

response to the site in the event of a terrorist or sabotage event. The 

coordination requires contingency plans and joint exercises with local 

law enforcement agencies to ensure an adequate and timely response to 
Appendix I: Nuclear Regulatory Commission 

Requirements for Safety and Security of 

Spent Fuel 

Page 33 GAO-03-426 Spent Nuclear Fuel 

an event. Since the terrorist attacks of September 11, 2001, NRC has 

added additional requirements, including additional armed guards and 

vehicle barriers. 

NRC requires that spent fuel in dry storage be stored in containers that 

protect workers and other nearby persons from significant amounts of 

radiation, and that can survive operational accidents at the storage site, as 

well as extreme meteorological and other natural events. In addition, fuel 

in dry storage is protected by physical security measures in place at the 

storage site. 

Among other things, dry storage containers must be capable of surviving 

• a drop test, in which containers are tested by a drop from the height to 

which it would be lifted to during operations; 

• a tip-over test, testing containers against seismic, weather, and other 

forces or accidents that could knock over 100- to 150-ton containers, 

• an explosion test, in which containers are tested against nearby explosions 

and the resulting pressures created by the blasts; 

• a tornado and tornado missile test, in which high winds and tornado 

missiles are simulated; 

• a seismic test, in which containers are tested against the seismic motions 

that might be expected to occur in its geologic area (certification 

requirements may differ from region to region); 

• a flood test, in which containers are analyzed for floods; and 

• a fire test, in which containers are engulfed at temperatures up to 

1,475 degrees Fahrenheit for 30 minutes. 

Manufacturers must provide NRC with information on how well a 

container design meets these performance requirements. NRC does not 

require physical tests of the containers, but it accepts information derived 

from scaled physical tests and computer modeling. 

Requirements for 

Preventing Release of 

Spent Fuel in Dry Storage 
Appendix I: Nuclear Regulatory Commission 

Requirements for Safety and Security of 

Spent Fuel 

Page 34 GAO-03-426 Spent Nuclear Fuel 

As with shipping containers, to meet these performance requirements, 

certified dry storage containers are massive and robust. A typical dry 

storage container consists of a 1-inch thick steel container housing the 

spent fuel. At some facilities, the containers are placed horizontally in 

garage-sized bunkers constructed of concrete. The concrete protects 

nearby workers and the public from radiation. At other facilities, the 

container is encased in an outer cask. The outer cask typically is 

constructed of steel-reinforced concrete, 18 or more inches thick. Like 

the concrete bunkers, the outer cask shields workers and the public from 

radiation. The free-standing, upright units, stored on concrete pads, can 

weigh from 100 to 150 tons each with nearly 90 percent of that consisting 

of the container weight. A dry storage container can store between 7 and 

68 assemblies, depending on the size of the container. See figure 6 for an 

illustration of a dry storage container. 
Appendix I: Nuclear Regulatory Commission 

Requirements for Safety and Security of 

Spent Fuel 

Page 35 GAO-03-426 Spent Nuclear Fuel 

Figure 6: A Spent Fuel Dry Storage Container 
Appendix I: Nuclear Regulatory Commission 

Requirements for Safety and Security of 

Spent Fuel 

Page 36 GAO-03-426 Spent Nuclear Fuel 

In addition to the physical performance requirements of dry storage 

containers, the containers are protected by the physical security measures 

in place at the facilities where they are stored. Dry storage containers at 

operating nuclear power plants generally benefit from the physical 

security measures already in place at the sites. The large majority of spent 

fuel in dry storage is located at operating nuclear power plants. For dry 

storage containers situated away from a reactor site, NRC requires vehicle 

barriers, fences, intrusion detection systems, and guards. The guards are 

also able to contact local law enforcement agencies for assistance, if 

required. NRC requires that dry storage facilities coordinate response 

plans with local law enforcement agencies to ensure assistance can be 

readily provided, if needed. In the wake of the September 11, 2001, 

terrorist attacks, NRC issued orders to dry storage facility licensees that 

required enhanced security measures, including additional protections 

against a vehicle bomb threat. 
Appendix II: Additional Information on 

Studies on the Safety and Security of Spent 

Fuel in Transit 

Page 37 GAO-03-426 Spent Nuclear Fuel 

The human health implications of sabotage events and accidents 

involving spent nuclear fuel shipments described in the report are based 

on computer-based engineering and other analytic models that rely, in 

part, on physical experiments. In addition, these studies are the most 

recent in a series of studies that date back to the 1970s. According to NRC 

and DOE, better data and improved analytic tools over the years have 

significantly enhanced the agencies’ confidence in the results of these 

studies. This appendix provides an overview of the methodology of the 

most recent studies, as well as the approach and results of previous 

studies. 

Methodology of Most Recent Studies. The 1999 Sandia National 

Laboratory study was undertaken at the request of DOE for use in its 

preparation of an environmental impact statement for the Yucca Mountain 

repository.1

 The study relied on computer models to estimate how the 

two selected armor-piercing missiles would damage shipping containers. 

Although no physical tests or experiments were conducted in this study, 

the study used computer models that were validated using the results of 

previous studies that included experimental data. 

Two of the most important factors considered in designing the study were 

the types of shipping containers and the weapons selected for analysis. 

For the shipping containers, the study used truck and rail containers 

considered representative of those that would be used to transport the 

spent fuel likely to be shipped in the early decades of the 21st Century. 

NRC’s performance standard for these containers requires that they 

prevent release of significant amounts of radiation under normal 

operating conditions and in accident scenarios. For example, radiation 

levels at the exterior of the container must remain below specified 

minimal levels after a series of tests to simulate accident conditions, 

including an impact test, in which the container is dropped from 30 feet 

onto a flat, unyielding surface. 

In selecting the weapons used in the analysis, the authors researched the 

latest information available and chose weapons they believed represented 

 1

 Sandia National Laboratory, Projected Source Terms for Potential Sabotage Events 

Related to Spent Fuel Shipments, SAND 99-0963, a report prepared at the request of the 

Department of Energy, Albuquerque, N.Mex., June 1999. 

Appendix II: Additional Information on 

Studies on the Safety and Security of Spent 

Fuel in Transit 

Sabotage Studies 
Appendix II: Additional Information on 

Studies on the Safety and Security of Spent 

Fuel in Transit 

Page 38 GAO-03-426 Spent Nuclear Fuel 

the two weapons that would penetrate spent fuel shipping containers, and 

which could also be available to terrorists.2

To ensure that the analysis would represent the upper limit of possible 

damage, the authors made conservative assumptions, including the 

following: 

• No security measures were in place, such as armed guards who travel with 

spent fuel shipments and who are required to have the capability to 

contact local law enforcement personnel in the event of an attack. 

• The weapons would be employed at a distance from these containers that 

would result in maximum damage to the container and that the weapon 

would strike the container dead center; if the missile were to strike higher 

or lower, it could be deflected by the cylindrical shape of most containers, 

and penetration of the container would be lessened or not occur at all. 

Previous Studies. The 1999 Sandia study is the most recent in a series of 

federally sponsored studies dating back to the 1970s that have examined 

the ability of armor-piercing weapons to penetrate spent fuel containers. 

A draft version of a Sandia study from 1978, for example, concluded that 

a successful sabotage attack on a spent fuel container would not cause 

prompt fatalities but could cause several hundred latent cancer fatalities in 

a densely populated urban area.3

 The final version of this study reduced 

the total latent cancer fatalities to fewer than 100, based on a re-evaluation 

of the quantity of radioactive material released.4

 Based largely on the 

initial draft of this study, NRC established its regulations for security of 

spent fuel in transit. Because this study was based on a conservative set of 

analytical assumptions instead of on experimental data, there was a high 

degree of uncertainty regarding the quantities of radioactive material 

released, and the human health consequences. Consequently, in 1983, DOE 

commissioned Sandia National Laboratory to conduct physical tests, in 

which armor-penetrating missiles were fired at shipping containers 

 2

 According to NRC, information on the types of weapons used in this analysis is classified. 

3

 Sandia National Laboratory, Transport of Radionuclides in Urban Environs: Working 

Draft Assessment, SAND 77-1927, Albuquerque, N.Mex., 1977. 

4

 Sandia National Laboratory, Transport of Radionuclides in Urban Environs: Draft 

Environmental Assessment NUREG/CR-0743, Albuquerque, N.Mex., July 1980. 
Appendix II: Additional Information on 

Studies on the Safety and Security of Spent 

Fuel in Transit 

Page 39 GAO-03-426 Spent Nuclear Fuel 

containing mock spent fuel assemblies.5 The study found that, under the 

worst-case scenario, about 24 ten-thousandths (0.0024) of 1 percent of the 

total solid fuel inventory in the container could be released as respirable 

particles.6 To estimate the human health impact, the study included 

conservative assumptions, including that the attacks occurred in 

Manhattan, in New York City, on a business day, that the fuel had been 

removed from the reactor for only 150 days (and thus was comparatively 

more radiologically dangerous), and that no evacuation took place to limit 

human exposure. Based on these results and assumptions, the study 

predicted no early deaths and between two and seven long-term latent 

cancer fatalities. 

Methodology of Most Recent Studies. According to NRC, the 2000 

Sandia National Laboratory study was conducted to address three 

developments—the likelihood that spent fuel shipments would be 

increasing as a result of the progress on the Yucca Mountain repository, 

the use of containers and transportation routes that differed from those 

considered in previous studies, and the increased effectiveness in risk 

assessment and computer modeling of spent fuel containers.7

 The overall 

objective of the study was to determine the degree of risk involved in 

shipping spent fuel by truck and rail. 

The study examined the effects of severe collisions and fires on four 

types of shipping containers—a lead-lined steel truck container, a 

depleted uranium-lined steel truck container, a lead-lined steel rail 

container, and a monolithic steel container. The study relied on computer 

analysis to estimate the probability of such events and the quantity of 

radioactive material that might be released. The analysis developed 

19 representative truck accidents and 21 representative rail accidents. 

 5

 According to Sandia National Laboratory officials, in addition to the high cost, 

environmental and health regulations generally prevent the use of actual spent fuel that 

leads to the use of mock fuel—a nonradioactive material—that generally displays enough 

of the same properties as spent fuel for purposes of these analyses. 

6

 Sandia National Laboratory, An Assessment of the Safety of Spent Fuel Transportation 

in Urban Environs, Albuquerque, N.Mex., June 1983. 

7

 U.S. Nuclear Regulatory Commission, Reexamination of Spent Fuel Shipment Risk 

Estimates, NUREG/CR-6672, Washington, D.C., March 2000. 

Accident Studies 
Appendix II: Additional Information on 

Studies on the Safety and Security of Spent 

Fuel in Transit 

Page 40 GAO-03-426 Spent Nuclear Fuel 

The study simulated the effect on each of the truck and rail containers 

after slamming them into a rigid surface from a variety of angles at 30, 60, 

90, and 120 miles per hour. None of the cases modeled showed that the 

body of the container would fail. Moreover, the modeling showed that the 

seals around the lid at each end of the truck container would not allow a 

release at 30, 60, and 90 miles per hour, although they may leak at 

120 miles per hour. The results from modeling the two different rail 

containers, however, showed that the seals may leak, for some collisions 

at a speed of 60 miles per hour, depending on the angle of impact. 

DOE’s study that predicted the health effects of these releases used a 

computer code. The code calculated the dispersion of radioactive particles 

and the resultant dose to the population. To estimate latent cancer deaths, 

DOE made a number of key assumptions. DOE’s analysis assumed the 

accident occurred in the most populous center of an urban area and that 

the population distribution from the accident site in the urban center to 

the outer fringes was similar to the average populations—projected to the 

year 2035—of the 20 largest U.S. metropolitan areas, plus Las Vegas, 

Nevada. Stable weather conditions—with comparatively slow wind 

speeds—were assumed to prevail at the time of the accident.8

 Finally, the 

population was assumed to be exposed to remnants of the release for 1 

year after the accident, with no evacuation or cleanup. 

Previous Studies. The 2000 Sandia study reexamined the risks 

associated with the transport of spent fuel by truck and rail and compared 

the results to two previous studies—one conducted by NRC in 1977 and 

one performed by DOE’s Lawrence Livermore National Laboratory in 

1987. According to NRC, the 2000 Sandia study extended the methods 

used in the 1987 report for container analysis and used improved risk 

assessment methods. 

The 2000 Sandia study found that previous NRC-commissioned studies 

overestimated the risks of human exposure due to transportation 

accidents. According to NRC and Sandia officials, they have become more 

confident in their results as analytical techniques and data have improved. 

In 1977, NRC examined the risks of shipping a variety of radioactive 

materials, including spent fuel.9

 At that time, NRC determined that the 

 8

 Higher wind speeds would result in faster dispersion and hence a lower population dose. 

9

 U.S. Nuclear Regulatory Commission, Final Environmental Statement on the 

Transportation of Radioactive Material by Air and Other Modes, NUREG-0170, 

Washington, D.C., 1977. 
Appendix II: Additional Information on 

Studies on the Safety and Security of Spent 

Fuel in Transit 

Page 41 GAO-03-426 Spent Nuclear Fuel 

risks of accidental releases involved in shipping spent fuel and other 

radioactive materials were quite small—specifically, the study estimated 

latent cancer deaths to be about 3 in 200 years of shipping spent fuel at 

estimated rates for 1985. The study concluded that the existing NRC 

requirements were adequate to protect public health. Partly because this 

study was based on conservative engineering judgments and did not 

include physical tests of shipping containers in severe accidents, NRC 

subsequently commissioned a study published in 1987 that found that the 

risks of spent fuel releases under transportation accident conditions were 

much smaller.10 Performed by Lawrence Livermore National Laboratory 

for NRC, this study included a more sophisticated analysis than the 1977 

study, using historical data on past transportation accidents to determine 

the likelihood of specific accident scenarios. The study then used a 

computer-based analysis of accident scenarios involving collisions and fire 

temperatures exceeding NRC standards. The 1987 study found that in 

99.4 percent of all rail and truck accidents, the container would experience 

no significant damage, and no radioactive material would be released. 

 10 Lawrence Livermore National Laboratory, Shipping Container Response to Severe 

Highway and Railway Accident Conditions, NUREG/CR-4829, a report prepared at the 

request of the Nuclear Regulatory Commission, 1987. 
Appendix III: Comments from the Department 

of Energy 

Page 42 GAO-03-426 Spent Nuclear Fuel 

Appendix III: Comments from the 

Department of Energy 
Appendix IV: Comments from the Nuclear 

Regulatory Commission 

Page 43 GAO-03-426 Spent Nuclear Fuel 

Appendix IV: Comments from the Nuclear 

Regulatory Commission 
Appendix IV: Comments from the Nuclear 

Regulatory Commission 

Page 44 GAO-03-426 Spent Nuclear Fuel 
Appendix V: GAO Contact and Staff 

Acknowledgments 

Page 45 GAO-03-426 Spent Nuclear Fuel 

Daniel J. Feehan (303) 572-7352 

In addition to the individual named above, Doreen Feldman, Michael 

Hartnett, Gary Jones, Cynthia Norris, Robert Sanchez, Amy Stewart, 

Barbara Timmerman, and Dwayne Weigel made key contributions to 

this report. 

Appendix V: GAO Contact and Staff 

Acknowledgments 

GAO Contact 

Acknowledgments 

(360181) 
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