[ If we don’t clean up nuclear waste while there is still the energy and a functioning financial system to make it happen, it won’t. Yet another nightmare for future generations. Shameful. Disgusting.
Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”]
USGAO. August 2012. Spent Nuclear Fuel. Accumulating Quantities at Commercial Reactors Present Storage and Other Challenges. United States Government Accountability Office GAO-12-797
Nuclear fuel that has been used and removed from the reactor core of a nuclear power plant—known as spent nuclear fuel—is one of the most hazardous substances created by humans. Some radioactive components of spent fuel remain hazardous for tens of thousands of years. In the United States, the national inventory of commercial spent nuclear fuel amounts to nearly 70,000 metric tons.
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.
The amount of spent fuel stored on-site at commercial nuclear reactors will continue to accumulate—increasing by about 2,000 metric tons per year and likely more than doubling to about 140,000 metric tons—before 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.
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,
Transferring spent fuel from wet to dry storage offers several key benefits, including safely storing spent fuel for decades after nuclear reactors retire—until a permanent solution can be found—and reducing the potential consequences of a pool fire. Transferring spent fuel from wet to dry storage is generally safe, but there are risks to moving it,
If not properly contained or shielded, the intense radioactivity of spent fuel can cause immediate deaths and environmental contamination and, in lower doses, cause long-term health hazards, such as cancer.
DOE is charged with investigating sites for a federal geologic repository to dispose of spent nuclear fuel and high-level nuclear waste from commercial nuclear power plants and some defense activities under the Nuclear Waste Policy Act of 1982, as amended. In 1987, however, Congress amended the act to direct DOE to focus its efforts only on Yucca Mountain, Nevada and to contract with commercial nuclear reactor operators to take custody of their spent nuclear fuel for disposal at the repository beginning in January 1998, but because of a series of delays due to, among other reasons, state and local opposition to the construction of a permanent nuclear waste repository in Nevada and technical complexities, DOE was unable to begin receiving waste by that time. Because it did not take custody of the spent fuel starting in 1998, DOE reports that as of September 2011, 76 lawsuits have been filed against it by utilities to recover claimed damages resulting from the delay. These lawsuits have resulted in a cost to taxpayers of about $1.6 billion from the U.S. Treasury’s judgment fund. DOE estimates that future liabilities will total about an additional $19.1 billion through 2020 and that they may cost about $500 million each year after that.
This report does not address the about 13,000 metric tons of spent nuclear fuel and high-level waste DOE manages, which was primarily generated by the nation’s nuclear weapons program. For example, DOE manages some former commercial spent fuel, such as spent fuel at a reactor at Fort St. Vrain in Colorado.
Spent nuclear fuel consists of thumbnail-sized pellets of uranium dioxide fitted into 12- to 15-foot hollow metal rods, which are bundled together into assemblies. Operators of commercial nuclear power reactors use two methods to store spent nuclear fuel: wet storage in pools of water or dry storage in steel and concrete casks. When reactor operators first remove spent fuel from a reactor, it is thermally hot and intensely radioactive and must be immersed in deep pools of water, which cools the spent fuel and shields the environment from the spent fuel. As the inventory of spent fuel has grown, reactor operators have increased the number of assemblies stored in the pools—generally 40 feet deep—by replacing existing storage racks with newer racks holding denser arrangements of assemblies. Despite the denser arrangements, which can sometimes hold thousands of assemblies, spent fuel pools have limited capacity. Beginning in the 1980s, reactor operators began to transfer spent fuel to dry cask storage systems to free space in the pools for fuel removed from the reactor. Spent fuel can be transferred to dry storage once it has aged sufficiently to be cooled by passive air ventilation—generally after about 5 years. Dry cask storage typically consists of a stainless steel canister placed inside a larger stainless steel or concrete cask, which isolates it from the environment. Dozens of community action and environmental groups have advocated that reactor operators accelerate the transfer of spent fuel from pools to dry storage cask systems, believing the risks of dry storage are lower than that of wet storage. NRC maintains that spent fuel is safe and secure in both wet and dry storage systems.
Fuel for commercial nuclear power reactors is typically made from low-enriched uranium fashioned into thumbnail-size ceramic pellets of uranium dioxide. These pellets are fitted into 12- to 15-foot hollow rods, referred to as cladding, made of a zirconium alloy. The rods are then bound together into a larger assembly. A typical reactor holds about 100 metric tons of fuel when operating—generally from 200 to 800 fuel assemblies. The uranium in the assemblies undergoes fission—a process of splitting atoms into fragments and neutrons that then bombard other atoms—resulting in a sustainable chain reaction that creates an enormous amount of heat and radioactivity. The heat is used to generate steam for a turbine, which generates electricity. The fragments created when fission splits atoms, or when bombarding neutrons bond with atoms, include hundreds of radioisotopes, or radioactive substances, such as krypton-90, cesium-137, and strontium-90. Furthermore, the neutron bombardment of uranium can also create heavier radioisotopes, such as plutonium-239. The radioisotopes produced in a reactor can remain hazardous from a few days to many thousands of years; these radioisotopes remain in the fuel assemblies and as components of the resulting spent fuel.
Each fuel assembly is typically used in the reactor for 4 to 6 years, after which most of the fuel it contains is spent, and the uranium dioxide is no longer cost-efficient at producing energy. Reactor operators typically discharge about one-third of the fuel assemblies every 18 months to 2 years and place this spent fuel in a pool to cool. Water circulates in the pool to remove the enormous heat generated from the radioactive decay of some of the radioisotopes. As long as circulating water continues to remove this heat, pool water temperature is maintained well below boiling, typically below 120 degrees Fahrenheit. If exposed to air, however, recently discharged spent fuel could rise in temperature by hundreds or thousands degrees Fahrenheit. A pool is needed to ensure that heat generated from the decay of radioisotopes, particularly immediately after discharge from a reactor, does not damage fuel rods and release radioactive material
The pools of water are typically about 40 feet deep, with at least 20 feet of water covering the spent fuel, and the water is cooled and circulated to keep the assemblies from overheating. These pools are constructed according to NRC’s requirements, typically 4- to 6-feet thick with steel-reinforced concrete and a steel liner. The pools must be located inside what is known as the vital area of a nuclear power reactor, protected by armed guards, physical barriers, and limited access. Within the vital area, pools may be in one of two locations, depending on the type of reactor. In a pressurized water reactor, spent fuel is stored in a pool at or below ground level, but in a typical boiling water reactor, spent fuel is stored in a pool well above ground level, near the reactor vessel, as high as three stories above ground.
To remove a spent fuel assembly from the reactor, an operator must stop the nuclear chain reaction, then allow the water in the reactor to depressurize and cool before accessing the fuel assemblies, a process that typically takes several days. Once spent fuel is discharged from a reactor and placed in a pool, the spent fuel continues to decay into other substances and continues to generate enormous amounts of heat.16 For example, plutonium-239—one of the components of spent fuel—decays into various radioactive substances, such as thorium and radium, and eventually decays into a stable, nonradioactive form of lead, although the entire process may take millions of years. As a general rule, the older the spent fuel, the cooler and less hazardous it is, but the spent fuel still has enough long-lived components to make it dangerous to humans and the environment for tens of thousands of years.
Typically, according to NRC officials, spent fuel must remain in a pool for at least 5 years to decay enough to remain within the heat limits of currently licensed dry cask storage systems. Spent fuel cools very rapidly for the first 5 years, after which the rate of cooling slows significantly. Spent fuel can be sufficiently cool to load into dry casks earlier than 5 years, but doing so is generally not practical. Some casks may not accommodate a full load of spent fuel because of the greater heat load. That is, the total decay heat in these casks needs to be limited to prevent the fuel cladding from becoming brittle and failing, which could affect the alternatives available to manage spent fuel in the future, such as retrieval. In recent years, reactor operators have moved to a slightly more enriched fuel, which can burn longer in the reactor. Referred to as high-burn-up fuel, this spent fuel may be hotter and more radioactive coming out of a reactor than conventional fuel and may have to remain in a pool for as long as 7 years to cool sufficiently. In the original designs submitted for spent fuel pools, fuel assemblies were packed in relatively low densities, but operators have replaced these low-density racks with higher-density racks to store more spent fuel. According to NRC officials, NRC accepts high-density storage of spent fuel if certain conditions are met, such as adequate cooling, the maintenance of structural integrity, and the prevention of a critical chain reaction. Neutron-absorbing materials can be used to keep closely packed assemblies from starting a chain reaction. As pools began to fill in the 1980s, NRC conducted several safety studies on the impact of increasing the density of spent fuel in pools and determined that the risk of a potential release from overheating or igniting, or even of a critical chain reaction from the dense geometric configuration, was small, particularly if certain steps were taken to reduce the risk. Even with re-racking to a dense configuration, however, spent nuclear fuel pools are reaching their capacities and may contain several thousand assemblies each.
As reactor operators have run out of space in their spent fuel pools, more operators have turned to dry cask storage systems. These systems consist of a steel canister protected by an outer cask made of steel or steel and concrete to provide shielding from the heat and radiation of spent fuel. In one typical process of transferring spent fuel to dry storage, reactor operators place a steel canister inside a larger steel transfer cask and lower both into a pool. Spent fuel is loaded into the canister, a lid is placed on the canister, and then both the canister and transfer cask are removed from the pool. The lid is welded onto the canister, and the water drained. Then the canister and transfer cask are aligned with a storage cask and the canister is maneuvered into the storage cask. The storage casks, in either vertical or horizontal designs, are usually situated on a large concrete pad surrounded by safety systems and a security infrastructure, such as radiation detection devices and intrusion detection systems.
In addition to regulating the construction and operation of commercial nuclear power plants, NRC also regulates spent fuel in dry storage. NRC requires that spent fuel in dry storage be stored in approved systems that offer protection from significant amounts of radiation. NRC evaluates the design of passively air-cooled dry storage systems for resistance to certain natural disasters, such as floods, earthquakes, tornado missiles, and temperature extremes. NRC may require physical tests of the systems, or it may accept information derived from scaled physical tests and computer modeling. For example, dry storage systems must be able to withstand, among other things, being dropped from the height to which it would be lifted during operations; being tipped over by seismic activity, weather, or other forces or accidents; fires; and floods. NRC has also analyzed the performance of dry storage systems in different terrorist attack scenarios. Once a dry storage system is approved, NRC issues a certificate of compliance for a cask design. Currently, NRC may issue a cask certificate for a term not to exceed 40 years. Similarly, NRC may renew a cask certificate for a term not to exceed 40 years beyond the licensed life of the reactor in a combination of wet and dry storage. Four states, an Indian community, and environmental groups petitioned for review of NRC’s rule, however, arguing in part that NRC violated the National Environmental Policy Act by failing to prepare an environmental impact statement in connection with the determination. On June 8, 2012, the U.S. Court of Appeals for the District of Columbia Circuit held that the rulemaking did require either an environmental impact statement or a finding of no significant environmental impact and remanded the determination and rule back to NRC for further analysis.
NRC has not yet indicated what actions it will take in response to the court’s action.
The length of time that spent fuel can safely be stored in dry casks is uncertain. We earlier reported that experts agree that spent fuel can be safely stored for up to about 100 years, assuming regular monitoring and maintenance.
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. This amount is based on the assumption that the nation’s current reactors continue to produce spent nuclear fuel at the same rate—about 2,000 additional metric tons annually; that no new reactors are brought online; and that some decline in the generation of spent fuel takes place as reactors are retired. At the end of 2012, over 69,000 metric tons is expected to accumulate at 75 sites in 33 states, enough to fill a football field about 17 meters deep. Without central storage options or an available permanent disposal facility, spent fuel continues to accumulate at the sites where it was generated.
Current industry practice has been to store the spent fuel in the pools, with an industry expectation that, at some point, DOE would begin to take custody of it. In 2011, about 74 percent of commercial spent fuel was stored in pools, and the remaining 26 percent was in dry storage, but these proportions will slowly change as more pools fill and the spent fuel is transferred to dry storage. According to the Nuclear Energy Institute, by 2025, assuming no new reactors, the proportion of spent fuel in wet storage and dry storage should be roughly equal, about 50,000 metric tons in each. Shortly after 2055, when the last currently operating reactors’ licenses are expected to expire, and the reactors are expected to retire, virtually all the spent fuel arising from the current fleet will have been moved to dry storage. Figure 7 shows the trend of accumulated spent fuel and the rate of spent fuel transferred from wet storage to dry storage through 2067, according to our analysis of Nuclear Energy Institute data.
When it became evident that DOE was likely decades behind its deadline to pick up spent fuel, nuclear power plant operators began transferring spent fuel to dry storage to retain enough space in their pools to safely discharge fuel from their reactors. The rate of transfer differs by the operating and spent fuel characteristics of the reactor—that is, reactor type and size—as well as the size of the spent fuel pool. In general, reactor operators must transfer an average of three to six canisters each year to keep pace with the discharge of spent fuel from their reactors. Table 1 provides data on reactors and spent fuel and the rate of transfer anticipated to dry storage.
Reactor operators continue to fill their spent fuel pools until capacity is reached, in part because the transfer of spent fuel to dry storage is costly and time-consuming. Specifically, operators must take extensive steps to ensure that safety precautions to protect workers and the public are met. Before an operator can transfer a single fuel assembly to dry storage, the operator must train personnel and practice the procedure. According to industry representatives, these efforts involve several weeks of mobilization and demobilization of equipment before and after the transfer. The transfer of spent fuel to a single canister typically takes at least 1 week.
Our analysis showed that regardless of which storage or disposal scenario was considered, it would take at least 15 years to open an off-site location and decades to ship the spent fuel once the central storage or disposal facility became available.
The time needed for shipment depends on the amount of fuel accumulated and assumes a shipment rate of 3,000 metric tons per year—the rate that DOE developed as part of its plans for Yucca Mountain. Experts we consulted in our prior work agreed this rate was reasonable. A faster or slower shipping rate could affect the rate of continued accumulation or drawdown of the backlog. When we conducted our analysis in 2009, we reported that Yucca Mountain—the first scenario—was likely to offer the earliest option for off-site disposal, in 2020.
If the licensing process for Yucca Mountain were resumed in 2012, we estimate that DOE would require roughly at least 15 more years to open the site as a repository, or sometime around 2027. We estimate that the second scenario—for the federal government to site, license, construct, and open two centralized storage facilities—might take about 20 years, with completion in 2032, because of the complexities in siting, licensing, and constructing such facilities. We estimate that the third scenario—for a potential permanent disposal facility as an alternative to the Yucca Mountain repository—would take the longest to be realized, about 40 years, or 2052, because of the additional scientific analysis required to ascertain the safety of a permanent disposal facility.
As Many Nuclear Reactors Begin Closing in 2040, Growing Quantities of Spent Fuel May Be Stranded in Place
During the decades it will take to open a storage or disposal facility, many reactors will be retiring from service, “stranding” their accumulated spent fuel in a variety of different dry storage systems, with no easy way of repackaging them should repackaging be required to meet storage or disposal requirements.
Most U.S. reactors were built during the 1960s and 1970s and, after a 40-year licensing period with a possible 20-year extension, will begin retiring in large numbers by about 2030 and emptying their pools by about 2040.
NRC regulations require radioactive contamination to be reduced at a reactor to a level that allows NRC to terminate the reactor license and release the property for other use after a reactor shuts down permanently. This cleanup process—known as decommissioning—costs hundreds of millions of dollars per reactor, and NRC is responsible for ensuring that operators provide reasonable assurance that they will have adequate funds to decommission their reactors. Once a spent fuel pool is removed, reactor operators will have limited options for managing spent fuel. For example, if reactor operators need to repackage their spent fuel because a canister has degraded or because other transportation or disposal requirements must be met, they will have to build a new spent fuel pool or some other dry transfer facility, or they will need to ship their spent fuel to another site with a wet or dry transfer facility.
As of January 2012, the United States had nine decommissioned commercial nuclear power plant sites. Seven of these plants have completely removed spent fuel from their pools—a total of 1,748 metric tons—as well as all infrastructure except that needed to safeguard the spent fuel. The other two sites, which have a total of 5,103 metric tons of spent fuel in both wet and dry storage, are in the process of emptying their pools and transferring all their spent fuel to dry storage.
Assuming that no centralized storage or permanent disposal facility becomes available, our analysis indicates that by 2040, the amount of stranded spent fuel in closed commercial nuclear power plants will total an estimated 3,894 metric tons; by 2045, that amount could increase to 28,751 metric tons; and by 2050, the amount could be 62,237 metric tons. By 2067, nearly all of the 140,000 metric tons of spent fuel could be stranded in dry storage.
The Key Risk of Stored Spent Fuel Is Difficult to Quantify, but Some Mitigating Actions Have Been Taken
A 2006 National Academy of Sciences study also found that a spent fuel fire could release large quantities of radioactive materials into the environment and cause widespread contamination.
NRC officials, as well as studies by Sandia National Laboratories (commissioned by NRC) and the National Academy of Sciences (2006), informed us about the conditions that could lead to a fire. Such a fire could occur only if enough water in the spent fuel pool were lost, such as through drainage or boiling away, exposing roughly the top half of the fuel assemblies. Without sufficient water to keep spent fuel covered and cool, it is possible that some of the hotter assemblies—those most recently discharged from a reactor—could ignite. Furthermore, once started, a fire in a spent fuel pool would be very difficult to extinguish because, in such a case, the zirconium alloy making up the metal cladding surrounding the assemblies would react with oxygen and, when a certain temperature was reached, would begin a chemical reaction that releases energy and raises the temperature. Essentially, the fire becomes hotter and self-sustaining and, depending upon the density of spent fuel in the pool, could spread to other assemblies. On the basis of studies cited by NRC officials and a Sandia National Laboratories study, a fire in a fully drained pool can start at about 1,830 degrees Fahrenheit (about 1,000 degrees Celsius). A zirconium fire does not involve flames; rather, it burns like a welding torch.
The National Academy of Sciences stated in a 2006 study that the probability of a terrorist attack on spent fuel storage cannot be assessed quantitatively or comparatively and that it is not possible to predict the behavior and motivations of terrorists. This study noted, and a National Academy of Sciences official expressed concern, that in the NRC-sponsored studies available when the National Academy of Sciences was performing its work, NRC did not examine some low probability scenarios that could result in severe consequences and that, although unlikely, should be protected against.
Efforts to mitigate safety and security risks could reduce the effects of key factors in the dynamics of a potential fire in a spent fuel pool, according to our analysis of Sandia National Laboratories studies on pool fire scenarios. Still, disagreement exists—largely between community action groups and NRC—as to the appropriate density of assemblies in a spent fuel pool.
Representatives from community action groups we interviewed said that even with NRC’s mitigation efforts, spent fuel pools remain too densely packed and that the total amount of spent fuel in the pools should be reduced by accelerating the transfer of spent fuel into dry storage. In addition, a 2003 study led by a scholar at a community action group proposed open rack storage for spent fuel pools. Under this proposal, 20 percent of the pool assemblies would be transferred to dry storage, which would then allow an open channel on each side of the pool. This configuration would help promote air convection between the assemblies and, in turn, reduce the probability of an ignition and subsequent spread to other assemblies. The fewer assemblies that catch fire, the smaller the amount of potential radiation that could be released into the atmosphere.
NRC requires nuclear reactor sites to develop and implement strategies to maintain or restore cooling of reactor cores, containment, and cooling capabilities for spent fuel pools under circumstances due to explosions or fire—a requirement that includes providing sufficient, portable, and on-site cooling equipment. A Sandia National Laboratories study determined that when holes in pool structure cause significant water drainage, reactor operators would generally have from a few hours to a few days to replace lost water or cool spent fuel with sprays in an effort to prevent a fire. If no water drained, such as in a loss-of-power event that caused a loss of cooling and allowed the pool water to boil, reactor operators might have days or weeks. NRC officials said that as spent fuel is uncovered, sprays are efficient and effective in cooling fuel assemblies. They also told us that trade-offs exist between installed and portable spray systems. Installed spray systems can be operated remotely but are susceptible to damage during an event. Portable systems provide adequate spray and are stored at least 100 yards away from the pool in secure places, but in case of an event, reactor operators may not always have access to the pool area to use them because of radiation hazard or physical obstruction.
According to a member of a community action group we interviewed, replacement water and sprays may be effective in cooling spent fuel, but replacement water may not contain boron, which is needed to absorb neutrons and prevent a critical chain reaction. This member told us that there is no requirement for reactor operators to keep a supply of boron to add to replacement water.
After the Fukushima Daiichi nuclear power reactor accident, NRC in March 2012 supplemented existing requirements by issuing an order instructing nuclear power operators to install monitoring equipment to remotely measure a wider range of water levels in spent fuel pools. NRC issued a second order, also in March 2012, that required reactor operators to ensure the effectiveness of water mitigation measures. It is more difficult to provide sprays and replacement water to boiling water reactor pools because they are typically several stories above ground and located close to the reactor,33whereas spent fuel pools for pressurized water reactors are at ground level or partially embedded in the ground. At Fukushima Daiichi, cooling flow to the spent fuel pool was lost during the loss of off-site power and was not immediately restored with the use of emergency diesel generators. Emergency operators did not have remote monitoring equipment to determine whether pool water levels had dropped enough to expose the spent fuel.
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 a release is less likely for the following reasons:
Spent fuel cools rapidly, and spent fuel in dry storage—typically at least 5 years old—has cooled sufficiently so that ignition is less likely. In addition, passive air cooling in dry cask storage systems is not affected by the loss of off-site power, and active monitoring—other than ensuring that air vents are not clogged—is not necessary to prevent overheating and possible ignition.
The amount of radioactive material in a dry storage canister is a fraction of the amount of radiation in a spent fuel pool. According to the National Academy of Sciences’ 2006 study, each dry storage canister contains 32 to 68 fuel assemblies—whereas thousands of assemblies are typically stored in pools—and therefore each canister has less radioactive material that can be released than the radiation from a pool. Logically, breaching dozens of spent fuel canisters simultaneously could result in more severe consequences than a single breached canister, but breaching dozens of canisters simultaneously is difficult.
To trigger any severe off-site radiological release from spent fuel stored in a canister, the fuel would have to undergo aerosolization, which would entail breaching the outer and inner shielding units. Furthermore, any holes would have to be sufficiently large enough to allow release of the aerosolized spent fuel. It would be difficult to aerosolize radioactive material in dry storage and difficult to have some mechanism to transport the radioactive material away from the reactor site. Such mechanisms would require energy, such as a fire.
Dry storage is not as susceptible to the buildup of hydrogen as are spent fuel pools. If an accident or attack involving a spent fuel pool causes a loss of water, the fuel assemblies can heat up and produce steam. This steam can react with the hot zirconium cladding surrounding the fuel assemblies, producing hydrogen that, when mixed with oxygen, could cause an explosion and structural damage to the reactor building.
Once a reactor is decommissioned, spent fuel is less expensive to safeguard in dry storage than in wet storage. Specifically, we previously reported that the cost of operating a spent fuel pool at a decommissioned reactor could range from about $8 million to nearly $13 million a year but that the cost of operating a dry storage facility might amount to about $3 million to nearly $7 million per year.38 Nine reactor sites nationwide are currently shut down and partly decommissioned and have already transferred all their spent fuel to dry storage or are in the process of doing so, with plans to remove their spent fuel pools.
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.
Accelerating the transfer of spent fuel is not justified, particularly given the billions of dollars it will cost, with no appreciable increase in safety.
A single fuel assembly from a boiling water reactor weighs about 700 pounds, and a single fuel assembly from a pressurized water reactor weighs about 1,500 pounds; dry storage casks, once fully loaded, can weigh from 100 to 180 tons or more.
Timing preferences and operational limitations could constrain how much spent fuel is transferred in a given year and may present an obstacle to accelerated transfer from wet to dry storage. Industry representatives told us that under current practice, reactor operators prefer to transfer spent fuel to dry storage during periods of time that do not interfere with refueling, receiving new fuel, required inspections, and maintenance or other activities vital to plant operations. These activities typically consume about 8 to 9 months of each year’s calendar. A routine dry storage loading operation may take 2 months or more, according to industry representatives. For example, one industry representative told us that it can take about 2 weeks to mobilize workers and equipment before the operation and about 2 more weeks to demobilize after the operation. Additionally, according to industry representatives at one operating reactor site we visited, each canister takes about 1 week to load, dry, seal, and move to a storage pad, which limits the number of canisters that can be loaded in a given year. In addition, spatial limitations—such as space for drying or welding lids onto multiple canisters, limited heavy lifting capabilities, and lack of free space in spent fuel pools to accommodate more than one cask at a time—may make simultaneous loading of canisters difficult. Some industry representatives we spoke with told us that there are limits on how much acceleration can be achieved in a single year.
Increasing costs. The transfer of spent fuel from wet to dry storage is costly in several ways. We estimated in a November 2009 report that the transfer cost for about five canisters is about $5.1 million to $8.8 million.46 One industry representative told us that if the transfer of spent fuel to dry storage were accelerated, the associated high upfront costs could strain some nuclear power plants’ budgets. These up-front costs, which would be incurred over a longer period without acceleration, include the construction of a storage pad with accompanying safety and security features, which, we reported, could cost about $19 million to $44 million.47 These costs are initially borne by ratepayers or plant owners but may be passed on to taxpayers as a result of industry lawsuits against DOE for failure to take custody of the spent fuel. Moreover, EPRI reported that as older, cooler spent fuel is loaded into canisters, reactor operators eventually will be left with younger, hotter spent fuel to transfer from wet to dry storage. Spent fuel stored in canisters generally should not exceed about 752 degrees Fahrenheit (400 degrees Celsius), and, as we reported earlier, spent fuel being discharged from reactors today may have to cool at least 7 years before it can be placed in dry storage. Given the heat load requirements for storing spent fuel, EPRI noted that it may not be possible to fill some canisters to capacity. Specifically, a canister with a capacity for 60 boiling water reactor assemblies that would store 60 older, cooler assemblies may be able to contain only 38 younger, hotter assemblies.
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 offsite 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.
Repackaging stranded spent fuel. Once reactors are decommissioned, reactor operators have limited options for managing the stored spent fuel.
Specifically, once they package the spent fuel in canisters and dry casks, they are unlikely to have any means of repackaging if the canisters degrade over the long term, or if the operators have to meet different storage or disposal requirements. As we previously reported, experts told us that canisters are likely safe for at least 100 years, but by then the spent fuel may have to be repackaged because of degradation.48 By the time such repackaging might be needed, reactor operators may no longer have pools or the necessary infrastructure to undertake the repackaging, as was the case at the Haddam Neck site we visited. Specifically, the Haddam Neck site had already decommissioned the reactor, transferred all its spent fuel from wet to dry storage, and dismantled its spent fuel pool. If the spent fuel at the site needed to be repackaged, a special transfer facility would need to be built, or the spent fuel would need to be shipped to a site that had a transfer facility. In addition, to reduce costs, reactor operators are selecting a variety of dry storage systems that maximize storage capacity. These varied systems do not raise safety issues, but they may complicate a transfer to a centralized storage facility or a permanent disposal facility because different systems require different handling requirements, such as the type of grappling hook and the size of the transport cask required. These differences may present more complex engineering challenges and cost issues as time passes, and the volume of spent fuel in various systems increases. In addition, over time, it is possible that handling equipment would not be maintained and personnel would not continue to be trained. Maximizing storage capacity may raise additional engineering challenges and cost issues, particularly since larger canisters may meet storage requirements but not transportation requirements. The Nuclear Energy Institute has reported that of all the spent fuel currently in dry storage, only about 30 percent is directly transportable. It also reported that the remaining spent fuel could need as much as 10 more years of cooling to meet NRC’s transportation heat-load requirements to ensure that assemblies can withstand the force of a potential accident.
Reducing community opposition . As reactors begin to be closed down and decommissioned, reactor operators will leave spent fuel on sites that will serve no other purpose than storing that fuel. Continued on-site storage would likely face increasing community opposition, which could make it difficult for operators to obtain NRC recertification for storage sites at reactors, approval for licenses to extend the operating life of other reactors, or licenses for new reactors. According to officials from a state regional organization we spoke with, the longer the federal government defers a permanent disposition pathway for spent fuel, the less likely the public would be to accept interim solutions, for fear such solutions would become de facto permanent solutions. Also, in our prior work, experts noted that many commercial reactor sites are not suitable for long-term storage and that none have had an environmental review to assess the impacts of storing spent fuel beyond the period for which the sites are currently licensed.
Managing costs. Continued storage of spent fuel may be costly. Because owners of spent fuel would have to safeguard it beyond the life of currently operating reactors, decommissioned reactor sites would not be available to local communities and states for alternative development. The Blue Ribbon Commission recommended that the nation open one or more centralized storage facilities and put a high priority on transferring the so-called stranded spent fuel to free decommissioned reactor sites for other uses. We previously reported the cost of developing two federal centralized storage facilities to be about $16 billion to $30 billion, although this estimate does not include final disposal costs, which could cost tens of billions of dollars more. In addition, we also previously reported that if spent fuel needs to be repackaged because of degradation, repackaging could cost from $180 million to nearly $500 million,51 with costs depending on the number of canisters to be repackaged and whether a site has a transfer facility, such as a storage pool.
Planning transportation to an off-site facility. The transportation of large amounts of spent fuel is inherently complex and may take decades to accomplish, depending on a number of variables including distance, quantity of material, mode of transport, rate of shipment, level of security, and coordination with state and local authorities. For example, according to officials from a state regional organization we talked to and the Blue Ribbon Commission report, transportation planning could take about 10 years, in part because routes have to be agreed upon, first responders have to be trained, and critical elements of infrastructure and equipment need to be designed and deployed. In addition, according to the Nuclear Energy Institute, some spent fuel in canisters that serve a dual purpose— both storage and transportation—might not be readily transportable because NRC’s transportation requirements for heat and radioactivity may require additional time for cooling and decay. To transport spent fuel before it is sufficiently cooled, reactor operators might have to repackage it or place it in more robust transportation casks. Uncertainties also surround the transportation of high-burn-up fuel. The Blue Ribbon Commission noted that NRC has not yet certified a shipping cask for the transport of high-burn-up fuels, which are now commonly being discharged from reactors. Spent fuel that has been stored for extended periods may become degraded and require additional handling before it can be transported. NRC has reported that the zirconium cladding of high-burn-up fuel is known to become more brittle after long cooling periods. Once sealed in a canister, the spent fuel cannot easily be inspected for degradation. If the cladding degrades, there is no assurance the spent fuel would remain in a safe configuration, potentially leading to a nuclear reaction if conditions were right. NRC officials told us that if they determined that a safe geometry could not be maintained during transportation because of cladding degradation, they would require the owner of the spent fuel to demonstrate that an uncontrolled critical chain reaction would not occur and would not issue an approval for transportation until they could assure a safe geometric configuration. In addition, NRC expressed concerns about the safe handling of spent fuel after transportation because of uncertainties over the condition of large amounts of high-burn-up fuel that might have to be repackaged for disposal. As a result, NRC stated that until further guidance is developed, the transportation of high-burn-up fuel will be handled on a case-by-case basis using the criteria given in current regulations.54 Without a standardized cask design for storage, transportation, and disposal, it may be difficult to design the type of large-scale transportation program needed to transfer high-burn-up fuel away from reactor sites.
Maintaining security over the long term. Future security requirements for the extended storage of spent fuel are uncertain and could pose additional challenges. Specifically, before the September 11, 2001, terrorist attacks, spent nuclear fuel was largely considered to be self-protecting for several decades because its very high radiation would prevent a person from handling the material without incurring health or life-threatening injury in a very short time, although incapacitating health impacts may sometimes not occur for up to 16 hours.55 In addition, as spent fuel decays over time, it produces less decay heat. A spent fuel assembly can lose nearly 80 percent of its heat 5 years after it has been removed from a reactor and 95 percent of its heat after 100 years. Given the willingness of terrorists in recent years to sacrifice their lives as part of an attack, the national and international communities have begun to rethink just how long spent fuel really might be self-protecting. As spent fuel ages and becomes less self-protecting, additional security precautions may be required.
Continuing taxpayer liabilities. The continued on-site storage of spent fuel will not alleviate industry’s lawsuits against DOE for failure to take custody of the spent fuel in 1998 as required by contracts authorized under the Nuclear Waste Policy Act of 1982, as amended. DOE estimates that the federal government’s liabilities resulting from the lawsuits will be about $21 billion through 2020 and about $500 million each year after that. These costs are paid for by the taxpayer through the Department of the Treasury’s Judgment Fund.
The International Atomic Energy Agency, DOE, and NRC have considered spent fuel to be self-protecting with a radiation level exceeding 100 rad—or, radiation absorbed dose, a unit of measurement—per hour at 1 meter unshielded. After short-term exposure to 250 to 500 rad, about 50 percent of the people coming in contact with the spent fuel would be expected to die within 60 days.
Conclusions
The decades-old problem of where to permanently store commercial spent nuclear fuel remains unsolved even as the quantities of spent fuel—in either wet or dry storage—continue to accumulate at reactor sites across the country.
It is not yet clear where a repository will be sited, but it is clear that it may take decades more to site, license, construct, and ultimately open a disposal site. In the interim, some scientists, environmentalists, community groups, and others have expressed growing concerns about the spent nuclear fuel that is densely packed in spent fuel pools, especially after the water in the pools at the Fukushima Daiichi nuclear power plant complex in Japan were at risk of being depleted, increasing the risk of widespread radioactive contamination. The chances of a radiation release are extremely low in either wet or dry storage, but the event with the most serious consequences—a self-sustaining fire in a spent fuel pool—could result in widespread radioactive contamination. NRC has studied the likelihood of such an event and has taken a number of steps to prevent a fire, including a number of mitigating measures, though some community action groups have raised questions if those steps are enough, given the severity of consequences.
Spent nuclear fuel—the used fuel removed from commercial nuclear power reactors—is an extremely harmful substance if not managed properly. The nation’s inventory of spent nuclear fuel has grown to about 72,000 metric tons currently stored at 75 sites in 33 states, primarily where it was generated. Under the Nuclear Waste Policy Act of 1982, DOE was to investigate Yucca Mountain, a site about 100 miles northwest of Las Vegas, Nevada, for the disposal of spent nuclear fuel. DOE terminated its work at Yucca Mountain in 2010 and now plans to transport the spent nuclear fuel to interim storage sites beginning in 2021 and 2024, then to a permanent disposal site by 2048. Transportation of spent nuclear fuel is a major element of any policy adopted to manage and dispose of spent nuclear fuel. This testimony discusses three key challenges related to transporting spent nuclear fuel: legislative, technical, and societal. It is based on reports GAO issued from November 2009 to October 2014.
Legislative challenges. As GAO reported in November 2009, August 2012, and October 2014, DOE does not have clear legislative authority for either consolidated interim storage or for permanent disposal at a site other than Yucca Mountain. Specifically, provisions in the Nuclear Waste Policy Act of 1982 that authorized the Department of Energy (DOE) to arrange for consolidated interim storage have either expired or are unusable. For permanent disposal, GAO reported in October 2014 that the amendments to the Nuclear Waste Policy Act of 1982 directed DOE to terminate work on sites other than Yucca Mountain. Without clear authority, DOE cannot site an interim storage or permanent disposal facility and make related transportation decisions for commercial spent nuclear fuel.
Technical challenges. As GAO reported in October 2014, experts identified technical challenges that could affect the transportation of spent nuclear fuel. These challenges could be resolved, but it would take time and could be costly. Specifically, GAO reported that there were uncertainties about the safety of transporting what is considered to be high burn-up spent nuclear fuel—newer fuel that burns longer and at a higher rate than older fuel— because of potential degradation while in storage. GAO also reported that guidelines for storage of spent nuclear fuel allow higher temperatures and external radiation levels than guidelines for transportation, rendering some spent nuclear fuel not readily transportable. In addition, GAO reported that the current transportation infrastructure, particularly for a mostly rail option of transportation—which is DOE’s preferred mode—may not be adequate without procuring new equipment and costly and time-consuming upgrades on the infrastructure.
Societal challenges. As GAO reported in October 2014, public acceptance is key for any aspect of a spent nuclear fuel management and disposition program—including transporting it—and maintaining that acceptance over the decades needed to implement a spent fuel management program is challenging. In that regard, GAO reported that in order for stakeholders and the general public to support any spent nuclear fuel program—particularly one for which a site has not been identified—there must be a broad understanding of the issues associated with management of spent nuclear fuel. Also, GAO found that some organizations that oppose DOE have effectively used social media to promote their agendas to the public, but that DOE had no coordinated outreach strategy, including social media. GAO recommended that DOE develop and implement a coordinated outreach strategy for providing information to the public on their spent nuclear fuel program. DOE generally agreed with GAO’s recommendation.
Spent nuclear fuel—used nuclear fuel that has been removed from the reactor core of a nuclear power reactor—is an extremely harmful substance if not managed properly. Without protective shielding, its intense radioactivity can kill a person who is directly exposed to it or cause long-term health hazards, such as cancer. In addition, if not managed properly, or if released by a natural disaster or an act of terrorism, it could contaminate the environment with radiation.
According to the Nuclear Energy Institute, as of 2012, only about 30 percent of spent nuclear fuel currently in dry storage is cool enough to be directly transportable. For safety reasons, transportation guidelines do not allow the surface of the transportation cask to exceed 185 degrees Fahrenheit (85 degrees Celsius) because the spent nuclear fuel is traveling through public areas using the nation’s public transportation infrastructure. NRC’s guidelines on spent nuclear fuel dry storage limit spent nuclear fuel temperature to 752 degrees Fahrenheit (400 degrees Celsius).
Scientists from the national laboratories and experts from industry we interviewed suggested three options for dealing with the stored spent nuclear fuel so it can be transported safely: (1) leave it to cool and decay at reactor sites, (2) repackage it into smaller canisters that reduce the heat and radiation, or (3) develop a special transportation “overpack” to safely transport the spent nuclear fuel in the current large canisters.
According to a 2013 DOE report, the preferred mode for transporting spent nuclear fuel to a consolidated interim storage facility would be rail. However, as we reported in October 2014, several experts from industry pointed out that not all of the spent nuclear fuel currently in dry storage is situated near rail lines; also, one of these experts said that procuring qualified rail cars capable of transporting spent nuclear fuel will be a lengthy process. Storage sites without access to a rail line may require upgrades to the transportation infrastructure or alternative modes of transportation to the nearest rail line. Constructing new rail lines or extending existing rail lines could be a time-consuming and costly endeavor. In addition, an industry official we interviewed noted that if spent nuclear fuel were trucked to the nearest rail line, the federal government would have to develop a safe method of transferring the spent nuclear fuel from heavy haul trucks onto rail cars.
Procuring qualified railcars may be a time-consuming process, in part because of the design, testing, and approval for a railcar that meets specific Association of American Railroads standards for transporting spent nuclear fuel.
In 1982, the congressional Office of Technology Assessment reported that public and political opposition were key factors to siting and building a repository. The National Research Council of the National Academies reiterated this conclusion in a 2001 report, stating that the most significant challenge to siting and commencing operations at a repository is societal. Our analysis of stakeholder and expert comments indicates the societal and political factors opposing a repository are the same for a consolidated interim storage facility.
Moreover, we reported in April 201118 and October 201419 that any spent nuclear fuel management program is going to take decades to develop and to implement and that maintaining public acceptance over that length of time will face significant challenges. We also reported in November 2009, that the nation could not be certain that future generations would have the willingness or ability to maintain decades-long programs we put into place today.20Of particular concern is having to transport spent nuclear fuel more than once, which may be required if some spent nuclear fuel is moved to an interim storage facility prior to permanent disposal. Some stakeholders have voiced concerns that because of this opposition to multiple transport events, a consolidated interim storage site may become a de facto permanent storage site.