	Background

In the United States, the national inventory of commercial spent nuclear  fuel amounts to nearly 70,000 metric tons, which is stored at 75 sites in  33 states (see fig. 1). DOE established the  commission, which studied alternatives including options for interim  storage of spent fuel and permanent disposal. Large Quantities of Spent Nuclear Fuel Are Expected to Remain at Commercial Reactor Sites for Decades

The amount of spent fuel accumulating at commercial reactor sites is  expected to increase by about 2,000 metric tons each year until it can  begin to be shipped off-site and, even then, shipping it off-site will be a  decades-long process. Spent Nuclear Fuel Could Nearly Double before Being Transported to a Storage or Disposal Facility

The amount of spent fuel is expected to more than double to about  140,000 metric tons by 2055, when the last of currently operating reactors  is expected to retire, according to the Nuclear Energy Institute, but it may  take at least that long to ship the spent fuel off-site. The Key Risk of Stored Spent Fuel Is Difficult to Quantify, but Some Mitigating Actions Have Been Taken

According to several studies on spent fuel storage, the key risk of storing  spent fuel at reactor sites is radiation exposure from spent fuel that has  caught fire when it is stored in a pool, but it is difficult to quantify the  probability of such an event. Radiological Release from a Pool Fire Is the Key Risk Posed by Spent Fuel Storage, but Quantifying This Probability Is Difficult

Radiation exposure—from a minor dose resulting from a work-related  accident to a severe, widespread release of radiation from a spent fuel  fire—is the key concern about the hazard of storing spent nuclear fuel. These early fatalities could be reduced or eliminated,  according to the study, if the radiation release was less severe and if  there were an early evacuation of the affected population. Spent Fuel in Dry Storage Is Less Susceptible to a Significant Radiological Release Than Is Spent Fuel Stored in Pools

Spent nuclear fuel in dry storage is less susceptible to a radiological  release of the magnitude of a zirconium fire in a spent fuel pool,  according to documents we reviewed and interviews we conducted with  officials from NRC, the National Academy of Sciences, and the Nuclear  Waste Technical Review Board; officials from industry; and  representatives of community action groups. Such mechanisms would require energy, such as a fire. If an accident or attack involving a spent fuel pool  causes a loss of water, the fuel assemblies can heat up and produce  steam. NRC Has No Centralized Mechanism to Help Identify, Locate, and Access Classified Studies on Spent Fuel

In conducting our work, we found that NRC does not have a mechanism  to ensure that it can easily identify and locate all classified studies  conducted over the years. To identify studies, we interviewed numerous NRC and other  officials and identified studies through references in other studies we  reviewed. Once spent fuel is in dry storage, additional  challenges may arise, such as costs for repackaging should it be needed. Accelerating Transfer of Spent Fuel from Wet to Dry Storage Presents Challenges and Some Risk

Accelerating the transfer of spent fuel from wet to dry storage entails  some operational challenges, and some industry representatives told us  that they have questioned whether the cost of overcoming these  challenges is worth the benefit, particularly considering the low probability  of a catastrophic release of radiation. Furthermore, in a 2003 response to  a recommendation by the Institute of Policy Analysis to accelerate the  transfer of spent fuel from wet to dry storage to reduce the likelihood and  potential consequences of a pool fire, NRC reported that accelerating the  transfer of spent fuel is not justified, particularly given the billions of  dollars it will cost, with no appreciable increase in safety. In commenting  on a draft of this report, NRC reiterated this position, stating that it does  not require the accelerated transfer of spent fuel to dry storage,  particularly considering the small increase in safety that could be  achieved, because it considers both wet and dry storage to be safe under  current regulations. Increasing costs. Managing Spent Fuel after Transfer from Wet to Dry Storage at Reactor Sites Presents Additional Challenges

Reactor operators had never intended to leave spent fuel on their sites for  extended periods, but even if the United States began to develop an off- site centralized storage or disposal facility today, spent fuel—which has  already been stored on-site for several decades—would be stored on-site  for several decades more. As a result, the following challenges could  affect decisions on managing spent fuel. Continued storage of spent fuel may be costly. Moreover, because storage or disposal facilities may take decades to  develop, in managing spent fuel, NRC and DOE officials and others with  appropriate clearances and a need to know may need to review classified  studies conducted by and for NRC on the safety and security of spent  fuel. Recommendation for Executive Action

To help facilitate decisions on storing and disposing of spent nuclear fuel  over the coming decades, we recommend that the Chairman of the  Nuclear Regulatory Commission direct agency staff to develop a  mechanism that allows individuals with appropriate clearances and the  need to know to easily identify and access classified studies so as to help  ensure that institutional knowledge is not lost. In  written comments, which are reproduced in appendix IV, NRC generally  agreed with the findings and the recommendation in our report.
Why GAO Did This Study

Spent nuclear fuel, the used fuel removed from nuclear reactors, is one of the most hazardous substances created by humans. Commercial spent fuel is stored at reactor sites; about 74 percent of it is stored in pools of water, and 26 percent has been transferred to dry storage casks. The United States has no permanent disposal site for the nearly 70,000 metric tons of spent fuel currently stored in 33 states. GAO was asked to examine (1) the amount of spent fuel expected to accumulate before it can be moved from commercial nuclear reactor sites, (2) the key risks posed by stored spent fuel and actions to help mitigate these risks, and (3) key benefits and challenges of moving spent nuclear fuel out of wet storage and ultimately away from commercial nuclear reactors. GAO reviewed NRC documents and studies on spent fuels safety and security risks and industry data, interviewed federal and state government officials and representatives from industry and other groups, and visited reactor sites.

What GAO Found

The amount of spent fuel stored on-site at commercial nuclear reactors will continue to accumulateincreasing by about 2,000 metric tons per year and likely more than doubling to about 140,000 metric tonsbefore it can be moved off-site, because storage or disposal facilities may take decades to develop. In examining centralized storage or permanent disposal options, GAO found that new facilities may take from 15 to 40 years before they are ready to begin accepting spent fuel. Once an off-site facility is available, it will take several more decades to ship spent fuel to that facility. This situation will be challenging because by about 2040 most currently operating reactors will have ceased operations, and options for managing spent fuel, if needed to meet transportation, storage, or disposal requirements, may be limited.
Studies show that the key risk posed by spent nuclear fuel involves a release of radiation that could harm human health or the environment. The highest consequence event posing such a risk would be a self-sustaining fire in a drained or partially drained spent fuel pool, resulting in a severe widespread release of radiation. The Nuclear Regulatory Commission (NRC), which regulates the nations spent nuclear fuel, considers the probability of such an event to be low. According to studies GAO reviewed, the probability of such a fire is difficult to quantify because of the variables affecting whether a fire starts and spreads. Studies show that this low-probability scenario could have high consequences, however, depending on the severity of the radiation release. These consequences include widespread contamination, a significant increase in the probability of fatal cancer in the affected population, and the possibility of early fatalities. According to studies and NRC officials, mitigating procedures, such as replacement water to respond to a loss of pool water from an accident or attack, could help prevent a fire. Because a decision on a permanent means of disposing of spent fuel may not be made for years, NRC officials and others may need to make interim decisions, which could be informed by past studies on stored spent fuel. In response to GAO requests, however, NRC could not easily identify, locate, or access studies it had conducted or commissioned because it does not have an agencywide mechanism to ensure that it can identify and locate such classified studies. As a result, GAO had to take a number of steps to identify pertinent studies, including interviewing numerous officials.
Transferring spent fuel from wet to dry storage offers several key benefits, including safely storing spent fuel for decades after nuclear reactors retireuntil a permanent solution can be foundand reducing the potential consequences of a pool fire. Regarding challenges, transferring spent fuel from wet to dry storage is generally safe, but there are risks to moving it, and accelerating the transfer of spent fuel could increase those risks. In addition, operating activities, such as refueling, inspections, and maintenance, may limit the time frames available for transferring spent fuel from wet to dry storage. Once spent fuel is in dry storage, there are additional challenges, such as costs for repackaging should it be needed. Some industry representatives told GAO that they question whether the cost of overcoming the challenges of accelerating the transfer from wet to dry storage is worth the benefit, particularly considering the low probability of a catastrophic release of radiation. NRC stated that spent fuel is safe in both wet and dry storage and that accelerating transfer is not necessary given the small increase in safety that could be achieved.

What GAO Recommends

To help facilitate decisions on storing and disposing of spent nuclear fuel over the coming decades, GAO recommends that NRC develop a mechanism for locating all classified studies. NRC generally agreed with the findings and the recommendation in the report.