Abstract
Despite the recommendations of the 2012 Blue Ribbon Commission Report, the US government has made no substantial progress toward the permanent, or even temporary, consolidated storage of used 1 civilian nuclear fuel. To complicate matters, a November 2013 decision by the United States Court of Appeals (2013) in Washington, DC eliminated the very fee designed to finance used-fuel storage—which had accumulated over $30 billion so far—introducing a further obstacle (Nuclear Energy Institute, 2014a).
It was not supposed to be this way. The 1982 Nuclear Waste Policy Act bound the federal government by law to take custody of all civilian waste from power companies for final disposal, under the assumption that the waste would be permanently stored in a deep geological repository at Nevada’s Yucca Mountain and overseen by the Energy Department. The Act obligated the US government to begin accepting waste by 1998, but the government was unable to fulfill this promise, forcing it to remunerate the utility companies for continuing to store the waste and assume liability. This situation cannot continue.
As a solution, the commission argues that the US government should establish a widely distributed series of regional, government-run sites that would take in the used fuel from the cooling pools of several reactors, thereby consolidating the interim storage of used fuel and putting this nuclear waste into stronger, safer, more secure, more manageable—and ultimately more affordable—dry casks, as a first step toward ultimate disposal. Dry casks have withstood earthquakes and floods, and are designed to withstand the heat of fires and the impact of airplanes; the 100-ton structures are hard to steal or damage, and require no cooling systems or power supplies. These are some of the many reasons why making the transition to dry cask-based interim storage should be made as quickly as possible, regardless of one’s opinion of civilian nuclear power.
When Congress passed the Nuclear Waste Policy Act of 1982, it earmarked Nevada’s Yucca Mountain as the site of a long-term, permanent geological repository for the radioactive waste from civilian nuclear power plants. The site was theoretically able to store tens of thousands of tons of used nuclear fuel for millennia, and the act committed the US government to begin accepting the used fuel there and at a supplemental repository beginning in 1998. A system was set up to pay for it all, called the Nuclear Waste Fund; lawmakers were so confident in this arrangement that the act banned storing used fuel anywhere else—except for the temporary storage of used fuel in the immediate vicinity of the reactors, usually in the reactors’ cooling ponds, for the first five years after removal from the core. (Used fuel loses the vast majority of its heat and some of its radioactivity during the period of pool storage, making it much less troublesome to transport or store.) When these cooling ponds filled up, as occurred on some sites, the excess used fuel was put into dry casks for temporary storage on-site while waiting for the permanent repository to be built. All well and good.
Except that Yucca Mountain was never opened, and the fee system instituted to pay for storing used fuel was struck down by the courts because the government had not met its contractual obligations. Meanwhile, there is no permanent place to put this radioactive waste, and the country’s nuclear reactors are running out of space to store it all. At the same time, the United States continues to generate used nuclear fuel at a rate of approximately 2,000 metric tons of uranium (MTU) per year (Holt, 2013), where it remains at reactor sites scattered across the country in cooling ponds or temporary dry casks, transforming 35 states into the unwilling de facto hosts of civilian nuclear used fuel. 2 There are now more than 70,000 metric tons of this material in the country. (One metric ton equals 2,204 pounds.) To put this figure into perspective, that’s more than 5,949,638 cubic feet, or the equivalent of filling a standard-sized NFL football field slightly more than 100 feet deep with used fuel. 3
What to do? One good, if potentially controversial, idea is to take advantage of the dry cask technology that reactor operators know so well from handling used nuclear fuel. Let’s have the Energy Department store these dry casks full of used fuel in consolidated, regional locations for interim storage, which the government would run until a permanent nuclear waste storage repository is created; these interim sites could potentially be safely used for many decades or even a century if need be. Admittedly, this proposal has the drawback of potentially putting off the decision on a permanent repository for a long time, and it would create fights about where the consolidated storage sites would be located and how the dry casks would be transported there. But at least the used fuel would be located in a dozen or so centralized locations instead of in various and sundry cooling pools and temporary dry cask storage sites near every one of the 100-plus reactors in the country. And such a system would be cheaper, more secure, more easily monitored, and safer from malevolent acts of nature and of man while a long-term solution is found.
But first, a brief history.
How we got here
Thirty-five states now store used commercial nuclear fuel totaling 71,775 metric tons, according to a December 31, 2013 inventory. 4 Of this used fuel in storage, 69 percent, or 49,542 metric tons, is in used fuel pools at reactor sites, while the remaining 31 percent, or 22,233 metric tons, is in 1,865 dry casks located at reactor sites or other so-called independent spent fuel storage installations. 5 This material has been accumulating since the first commercial nuclear power plants to generate electricity went online in the late 1950s (World Nuclear Association, 2014a). Since then, the United States has operated a total of 137 commercial nuclear reactors in 35 states and Puerto Rico. The vast majority of these were light water designs, 6 either pressurized water reactors or boiling water reactors.
To cover the anticipated expense of the proposed long-term storage of used fuel, utilities were required to pay a fee to the government for any used fuel already existing as of 1982. At the same time, a tax of one-tenth of a penny per kilowatt-hour, or $0.001/kWh—known as the millage (or mill) fee—was levied on all power generated after 1982 by nuclear reactors. This was all deposited into a Nuclear Waste Fund. This same act explicitly excluded the creation of interim storage facilities; any on-site used fuel pools were viewed purely as temporary fixtures, intended to be used only for that initial five-year cooling period, not decades-long storage.
For a variety of reasons, including opposition from the state of Nevada, the federal government was unable to fulfill this obligation. Consequently, the nuclear power plants’ operators have been responsible for storing their nuclear waste on-site, in used fuel ponds and in temporary dry casks. To pay for it, the utilities successfully and repeatedly sued the government for ongoing partial breach of contract. The legal maneuvering proved convenient for both sides: The utility owners, though required to responsibly store the used fuel, could recover their costs by suing the government; those utilities that had not yet paid the waste fee for their pre-1982 used fuel did not have to pay for moving this historical waste to a permanent repository. Meanwhile, from the government’s point of view, the legal maneuvering meant it could avoid making any commitments about a final storage solution; what’s more, it can pay the legal damages through a separate judgment fund not subject to congressional appropriations (Werner, 2012).
This last part is key, because access to the existing monies in the Nuclear Waste Fund requires going through the congressional appropriations process—a process that is unlikely to achieve success, given current political polarization and tight federal budgets. And with Yucca Mountain off-limits, the government is financially unable to create a new repository. At the same time, it cannot use the millage fee to generate new funds, because a recent federal court ruling prevents the federal government from collecting it. Consequently, used fuel continues to accumulate at reactor sites, in storage facilities not hardened against potential attacks or severe accidents. Thus, the private sector assumed responsibility for long-term storage of used civilian nuclear fuel.
Nuclear waste: Pressurized water reactors vs. boiling water reactors
Currently, there are 100 civilian nuclear power plants operating in the United States—65 pressurized water reactor (PWR) and 35 boiling water reactor (BWR) designs. Though both are light water designs, PWRs and BWRs have different fuel specifications regarding quantity, configuration, and “burn-up rate”—the percentage of fissile atoms that has experienced fission. 7
A pressurized water reactor generates more used fuel waste by volume. However, because of the composition of the used fuel from a boiling water reactor, a BWR has a greater heat load. As a result of its smaller yet hotter volume of used fuel, the waste from a BWR requires significantly different management and storage practices—a factor to consider when assessing the vulnerability and security of used fuel. The distinction between reactor type and fuel enrichment level can mean a difference of years required for the initial cooling period. (In contrast, the long-term, permanent storage of used fuel—no matter what its source—requires millennia to reduce its radioactive toxicity.)
Wet pool storage
Whether it comes from a PWR or BWR, after used fuel is removed from a reactor core, it is moved directly into cooling ponds, where the used fuel loses a significant proportion of its heat load in that key three- to five-year cooling period. Because the cooling process requires somewhat cold water that is physically circulated via pumps, the rate at which used fuel cools down varies according to flow rate, volume, water temperature, circulation patterns, and other factors, making it hard to state the actual cooling rate with any more precision other than to say that the Nuclear Regulatory Commission (NRC) considers five years sufficient to cool most used fuel for transfer to dry casks.
During this time, the most unstable fission products—including isotopes of cesium, strontium, and iodine—decay. Along with plutonium and the minor actinides such as americium and curium, these products constitute approximately three to five percent of the used fuel and are responsible for most of the heat load during the first few decades of storage. Current high-density used fuel ponds can contain thousands of fuel assemblies (bundles of fuel rods); for example, the storage pools in a GE Mark I boiling water reactor span 54,600 cubic feet (Werner, 2012), or a volume equivalent to roughly two-thirds of an official Olympic swimming pool. Tens of feet of water cool the used fuel; boron-treated metal separators absorb the neutrons emitted by the decaying fuel (Nuclear Regulatory Commission, 2014a). The used fuel pond is typically located adjacent to the reactor but housed in a separate building for most PWR designs, while in some older boiling water designs the used fuel pond is located above ground, close to the reactor core.
A site will have at least one pool per reactor; however, operators may redistribute and rearrange the used fuel in these pools as they see fit—a pool need not be dedicated to one particular reactor’s fuel. Used fuel pools located on the same site can be interconnected or separate (Pulvirenti and Hiser, 2011). Keeping the pools cool—typically, the water temperature is below 120 degrees Fahrenheit (49 degrees Celsius)—requires power to circulate the water; it is also necessary to carefully arrange the assemblies by age and fuel to control the decay process.
Once the fixed costs are paid for bringing the pool online and fitting the racks for the appropriate amount of fuel, the additional cost of each new assembly is very small, especially when compared to the other operating expenses for pool storage. The reactor’s owners may pay some more to cool the fuel or to implement the high-density racks, but this cost is relatively small.
As fuel inventories have grown, utilities have re-racked their pools to accommodate more assemblies, leading to what is called “high-density” fuel storage. These require different racks to hold the assemblies, with additional neutron-absorbing materials and changed configuration requirements to ensure that the used fuel is safe (Government Accountability Office, 2012). An arrangement is considered high-density if four assemblies that have been cooling for a long length of time surround an assembly more recently discharged from a reactor core. Conversely, a low-density arrangement has a recently discharged assembly surrounded by four empty spaces (Nuclear Regulatory Commission, 2014b).
Currently, 69 percent of the used nuclear fuel in the United States is stored in one of these pools. As a result of the move to high-density storage, some pools have thousands of assemblies each; even with high-density configurations, the total storage capacities of these pools are now being reached. When the pools are full, the utilities often move the oldest (and therefore coolest) assemblies into dry cask storage; thus, dry cask storage has so far been used largely as a safety valve for dealing with excess used fuel. Consequently, dry cask storage has been viewed as merely a temporary solution—something that we propose should be changed.
There are two reasons: First, because consolidated interim storage is necessary for meeting legal obligations within the next few decades; and second, because consolidated interim storage does not compromise either safety or security—while the status quo does.
Admittedly, there are political and legal considerations. For example, what if consolidated interim dry cask storage becomes permanent storage? And there is also a problem in the wording of the 1982 Nuclear Waste Policy Act itself, which declared the on-site interim storage of used fuel from civilian nuclear reactors to be the responsibility of the reactor operators and explicitly limited the volume of
To explain why regional centers of dry casks constitute a better, safer, and more secure storage method than the current system of numerous, widely scattered wet pools, we offer a primer about the key technology behind consolidated interim storage: dry casks.
Dry cask storage technology
The typical dry cask is a cylinder approximately 16 feet in length and about 8 feet in diameter, with 12- to 30-inch-thick walls of metal or concrete—materials that not only protect the used fuel but also absorb the emanating radiation. Within this outer shell is a leak-proof, sealed metal cylinder that contains the used fuel. The NRC describes such casks as designed to resist “earthquakes, projectiles, tornadoes, floods, temperature extremes and other scenarios” (Nuclear Regulatory Commission, 2013).
There are 21 NRC-approved dry cask storage system designs, made by four companies. Specifications for each cask, such as fuel capacity or heat load, change according to the cask’s purpose and the type of reactor from which the fuel was removed. There are casks used only for transporting fuel, casks just for immobile storage, and casks designed for both tasks (US Nuclear Waste Technical Review Board, 2010). But all casks have two things in common: They encase and protect the used fuel assemblies.
To ensure the protective casing of the cask will remain intact, and to keep the used fuel from releasing radiation, the casks undergo a series of checks for safety and robustness. These tests are done under normal, abnormal, and accident conditions.
Transportation casks, for example, are dropped 30 feet onto a solid, unyielding surface; engulfed in flames above 1,470 degrees Fahrenheit (800 degrees Celsius); dropped onto a vertical bar capable of puncturing them; and submerged in water for more than eight hours. These tests are meant to simulate the extreme conditions possible during transport, and ferret out structurally weak points (Nuclear Regulatory Commission, 2014b).
Storage casks are tested similarly and must also be able to protect their contents against natural disasters, including tsunamis, earthquakes, and tornadoes. The used fuel inside must remain safely encased, cool and intact (Nuclear Regulatory Commission, 2014b).
Each cask weighs more than 100 metric tons (about 220,500 US pounds)—the amount varies depending on design—when fully loaded. Typically, 10 to 20 tons of this weight is due to the fuel assemblies, while the cask’s concrete and steel account for the rest. The exact amount of used fuel that can be stored within a given cask varies by initial fuel enrichment levels, cask design, and whether the fuel came from a PWR or BWR.
Because of the extreme weight of a cask and its contents, moving one or knocking it over is very difficult, as shown when Fukushima Daiichi’s dry casks withstood both an earthquake and a tsunami without damage to themselves or their contents. In fact, even after being flooded and shaken, the casks still stand upright (Tokyo Electric Power Company, 2013). By comparison, the used fuel stored in the pools at Fukushima Daiichi suffered immense damage, mostly from the pools’ inability to cool the used fuel—a situation that continues to plague the Japanese government and the reactors’ owners.
Dry cask storage systems are either “bare-fuel” or “canister” systems. Bare-fuel systems are casks into which the used fuel is directly placed—unlike the canister system, in which the used fuel is sealed in a stainless steel canister first and then moved between casks.
The canisters themselves are half-inch- to one-inch-thick stainless steel, leak-proof cylinders approximately 5 feet in diameter and as much as 16 feet tall (BNG Fuel Solutions Corporation, 2005).
To load used fuel, the canisters are first placed in the cooling pool. Then the used fuel is transferred into the canister, and canister and contents are removed together as a unit from the pool to be dried and sealed; before being welded shut, the containers are backfilled with an inert gas such as helium. Putting in an inert gas allows the used fuel to be cooled by convection; it also prevents deterioration or re-oxidation of the zirconium alloy metal, or “fuel cladding,” that makes up the metal tubes of the fuel pins. (Also known as a “fuel rod,” each pin consists of a narrow, hollow tube about 16 feet long into which fuel is inserted in the form of pellets. These pins are arranged into bundles called fuel assemblies, which are then loaded into the reactor core.) If gas were not injected into the canister, the cladding could easily deteriorate or re-oxidize, allowing the used fuel to swell and crack the pins. Because the used fuel will eventually be moved to a final repository, if these pins were ruptured that would cause real problems in the attempt to move the material from the interior of the dry cask to the final disposal container at the end repository site.
After inserting the gas and welding the canisters shut, the canisters are put inside the cask.
This whole canister system provides an additional shield against radiation, as well as a first layer of protection against used fuel degradation and corrosion (EnergySolutions Spent Fuel Division, 2012). However, canisters are only one component of a dry storage system; they are not designed to protect the used fuel from accidents, unlike the casks into which they are loaded. The use of canister systems has become the standard operating procedure for storing used fuel because this method reduces the number of steps necessary to transfer and transport used fuel.
This canister system is purely designed for the transport of
Casks specially designed for transport then move the canisters from the reactor building to the storage sites where the canisters are loaded into the immobile storage casks. The entire process of loading, drying, and sealing the canisters takes approximately a week.
Canister systems significantly simplify transport, as the hefty storage casks can remain at the storage site, so that only the canisters need to be transferred. Once on-site, the casks are placed on a secured concrete pad for surveillance and monitoring. NRC regulations say that no more than 10,000 metric tons can be stored at any one site (Nuclear Regulatory Commission, 2011); dry cask storage sites are licensed to hold up to approximately 625 casks. 8
The current generation of casks is licensed for 20 years of use with a “certificate of compliance.” This license can be renewed for another period of “extended operation” after a full evaluation of the cask materials, fuel, fuel assemblies, and other essential components to ensure that the fuel is secure and ultimately retrievable at the end of the cask’s lifetime (Nuclear Regulatory Commission, 2011). There are annual fees associated with licensing each cask, which are billed and paid in addition to millage fees.
The security and safety properties of dry casks
While no solution is perfectly accident-proof, dry casks provide greater protection than storing the fuel in pools. The reasons are many.
First, dry casks have built-in “passive safety” features, in which safety measures automatically occur without the need for humans to directly intervene. For example, rather than needing a power supply or water circulation to keep the assemblies cool, casks are cooled by natural air circulation and convection (US Nuclear Waste Technical Review Board, 2010; Werner, 2012). This eliminates the possibility of a loss-of-coolant accident because none of the problems related to water loss and the generation of steam—and possible hydrogen—can arise. This does not mean that dry casks are risk-free or maintenance-free, but at least they do not require the constant monitoring and electric power needed for pool storage. Consequently, blackouts do not pose a safety risk to used fuel in dry cask storage.
In addition, accidents involving any one cask do not necessarily implicate all the surrounding casks. This factor reduces both operational risks and risks from attacks. Each cask is isolated from the next, limiting the amount of used fuel exposed in any one incident. In contrast, with pool storage, one incident affecting the pool affects all the assemblies it contains.
So far as malicious attacks on dry casks go, a successful attack would require a highly coordinated effort, all while presumably facing a vigorous response from law enforcement and security personnel. Because the casks are so huge, cumbersome, and heavily constructed, they are very difficult to steal or open to access the radioactive materials inside. Any attempt to penetrate dry casks would be quite time-consuming, giving security that much more time to respond. Used fuel pools offer none of these advantages.
Finally, if worse came to worst and a cask was breached, it is much easier to contain a possible leak or damage from a dry cask than to stabilize and restore an entire pool following an accident or attack (National Academy of Science, 2006).
In the case of stranded fuel, moving it to dry casks at consolidated interim storage sites from a pool would not only reduce operating costs but also ensure that the infrastructure is in place to deal with fuel degradation. Maintaining such infrastructure at decommissioned reactor sites is, in contrast, much more expensive (Government Accountability Office, 2012).
Why is interim storage a good idea?
Consolidated interim storage provides a number of benefits, even when a permanent repository has already been put in place.
There are several fundamental safety and security risks with the current method of storing used nuclear fuel in cooling pools. In a loss-of-coolant accident, the assemblies in the pool can boil off the pool water; this can lead to damaged fuel rods as well as possible meltdown of the fuel assemblies. And a loss-of-coolant accident could happen in so many ways: equipment failure, electrical blackout, or terrorist attack.
Another problem when water boils off is that the resulting steam reacts with the zirconium alloy cladding to generate hydrogen gas which, when mixed with air, can ignite and cause an explosion. The Japanese were fortunate that neither an assembly meltdown nor a hydrogen explosion occurred in Fukushima Daiichi’s used fuel pools, so the airborne spread of radioactive materials was much more limited than would have occurred otherwise.
By its very nature, the pool storage method is also more vulnerable to malicious attack, when compared to attacking the material located in the reactor core itself or sitting inside dry casks. Both dry casks and the containment structure surrounding the reactor pressure vessel are strong enough to withstand the impact of an airplane, for example, while the buildings that surround used fuel pools are structurally nothing more than warehouses, or “industrial grade structures” as the NRC calls them (Union of Concerned Scientists, 2011). All these considerations have become more urgent now that the operators of the current nuclear power reactor fleet are beginning to use higher burn-up fuel.
A 2006 National Academy of Sciences (NAS) report discussed different scenarios involving aerial, ground, and combination air-ground assaults on stored used nuclear fuel. The NAS committee considered an attack on a pool of used nuclear fuel to be the most plausible situation, resulting in the worst, most widespread consequences. (This was confirmed by other research emphasizing the harm caused by the likely loss of coolant during such an attack (Alvarez et al., 2003)). Such an attack is hard to simulate exactly, because the size and scale of any consequences would depend on many factors, including the age, configuration, amount of used fuel, and the mode of attack. Nevertheless, any attack on a used fuel pool would be devastating, considering the higher concentration of radionuclides in a used fuel pool compared to the reactor core. Furthermore, as the burn-up of the used fuel increases, so does the amount of harmful fission products, such as cesium 137, which would worsen any potential consequences (Alvarez et al., 2003).
Even under normal operation, fuel can degrade and corrode while stored in pools for extended periods of time. Degradation can come from a variety of causes, including embrittlement resulting from neutron damage, and also by corrosion caused by pools containing low pH levels and strongly growing bacteria. While the severity and the pattern of corrosion vary depending on the cladding’s material properties, the zirconium alloy has proven effective in resisting corrosion under normal conditions when the usual purified water with neutron-absorbing additives is used as a coolant. If impure water must be used instead—such as when seawater was introduced at Fukushima to cool down the used fuel in the storage pools and the fuel in the scrammed reactors (reactors in emergency shutdown mode)—one can expect substantial corrosion. In such an accident, even zirconium cladding is vulnerable (International Atomic Energy Agency, 1998). Such corrosion did occur at the shutdown Hanford Site in the state of Washington, motivating the construction of a new containment facility to prevent further problems and leakage from the pool (GlobalSecurity.org, 2014).
Thus, there are a number of reasons that used nuclear fuel should be moved from pools as quickly as realistically possible to more secure and safer storage, keeping the amount of used fuel in cooling pools to the minimum.
Demonstrating performance
One of the key problems bedeviling civilian nuclear power is the federal government’s inability to carry out its legal obligations and take ownership of civilian used nuclear fuel, as mandated in the 1982 Act. Because a functioning permanent repository is most likely to be decades away, the only way the federal government can move ahead is by pursuing interim storage. Any permanent repository alternative to Yucca Mountain will require enormous new financial resources, not likely to be available soon.
Past experience shows that it will likely take decades to site, build, and license a permanent repository, even under the best circumstances. This leaves the government with two options: remain with the status quo of leaving used fuel to be overseen by the utilities; or begin receiving fuel in consolidated interim dry storage under federal supervision.
The advantages to the status quo are that the federal government does not need to take any of the political risks entailed in building interim storage facilities, immediately move any waste, or deal with the fiscal challenges involved. It is always easier to “kick the can down the road” and delay the inevitable until it is some future administration’s problem. Indeed, one argument against consolidated interim dry cask storage is that it will become the “next can,” and consolidated interim dry cask storage could become another storage arrangement by default, one that reduces the incentives to construct a final repository. Though this is a very real possibility—reinforced by the August 26, 2014 NRC decision to allow indefinite aboveground storage of used nuclear fuel (Nuclear Regulatory Commission, 2014c)—consolidated interim dry cask storage is nevertheless the best way to proceed. Using consolidated interim storage allows the government to fulfill its current legal obligation. And the dry cask system is a safer method for storing used nuclear fuel on the timescale likely to be needed to establish a final permanent repository for used fuel.
There are many advantages to the federal government fulfilling its legal commitment to accept used fuel. For one thing, it would halt the ongoing lawsuits by utilities. So far, the 71 breached contracts have caused the US Judgment Fund to award approximately $1.2 billion to utilities (Garvey, 2009), $565 million of which has already been paid out (US House Committee on the Budget, 2009). For another, there are costs to delay, including the expenses involved in exposing the nuclear fuel cycle to unnecessary risks and the costs to the federal government’s reputation. Once used fuel can again be accepted by the federal government, it could reinstate the millage fee from the utilities—$750 million annually (Blue Ribbon Commission on America’s Nuclear Future, 2012)—restoring the flow of funds needed for long-run, permanent storage. What’s more, the government could start to reduce the cost of storing waste, especially at sites where reactors are no longer online, by minimizing the amount of used fuel located in storage pools. According to Nuclear Energy Institute estimates, it costs from $10 million to $20 million to build a consolidated regional dry storage site, with annual maintenance and operations fees ranging between $5 million and $7 million (Nuclear Energy Institute, 2014b). In contrast, maintaining fuel in on-site pool storage costs between $8 million and $13 million annually at a reactor that is shut down (Government Accountability Office, 2009).
Another benefit to starting now: reducing litigation costs. Federal liabilities grow every year that the government fails to accept used nuclear fuel. Currently, the Energy Department is arguing multiple cases in federal court, costing millions of dollars in legal costs and settlements with utilities—as of 2009, the Energy Department had paid upward of $154 million in litigation-related costs alone (Coyle, 2009). At this point, the US government, even if it began accepting used fuel in 2020, would still be required to make damage payments to utilities of $12 billion (US House Committee on the Budget, 2009). 9 A consolidated interim storage facility system could begin compliance in that time frame and help reduce the ever-increasing liabilities and litigation costs.
By potentially restoring the ability to collect the mill fee, the funding source for a permanent repository would be restored, rather than allowing damage payments to mount.
Addressing arguments against dry cask storage
While the advantages of interim consolidated regional dry cask storage in the United States are well recognized (Werner, 2012), there are challenges to making the transition. Moving to dry cask storage would require significant financial investments in building the supply chain that produces the casks, constructing the storage sites, transferring fuel into the casks, and positioning the casks on pads—and how all this would be paid for remains unclear. Second, there are risks involved with moving used fuel into casks and transporting it on roads and rails. Finally, dry cask storage is not a “build and forget” solution. There is still the risk of material degradation in the casks, and ongoing inspection and maintenance would be needed if used nuclear fuel is indeed allowed to remain in such aboveground storage indefinitely.
The supply chain presents a particularly significant hurdle. Currently, dry cask manufacturers cannot produce enough casks to keep up with the large-scale transfer of used fuel from reactor sites. It would take years to be able to meet the additional demand (Electric Power Research Institute, 2012). Furthermore, the capacity to transfer fuel from pools at each site is limited by the availability of site personnel and infrastructure—the equipment necessary to move these casks is expensive and often unavailable due to the need to conduct other necessary operations. Given these limitations, and considering that moving fuel can take up to a week per cask, some researchers estimate that moving all of the used fuel to casks would require more than a decade and cost between $3.5 billion and $3.9 billion in labor and new infrastructure (Electric Power Research Institute, 2012).
In addition, moving used fuel into dry storage would increase the radioactive exposure of any personnel making the transfers. Because the nuclear industry has moved to higher burn-up fuel, which has increased concentrations of highly radioactive materials (Electric Power Research Institute, 2012), this concern has increased. Nevertheless, no incident has occurred in the many years of transporting fuel—and an incident with one cask is dwarfed by an incident with one pool. Extensive studies, principally by Sandia National Laboratories, have validated the safety performance of dry casks and transportation casks. In addition, it is probable that, should the move to a system of consolidated dry cask interim storage gain momentum, new methods and materials will be developed that should improve safety.
Finally, although the risk of cladding and canister degradation in dry casks is small in the short term, it is not zero over the long run. Dry cask performance is not well understood on decades-long timescales. (The Energy Department is currently conducting a High Burnup Dry Storage Cask Research and Development Project to better understand the behavior of dry cask storage over longer time periods (Electric Power Research Institute, 2014)). It is possible that the casks may need to be replaced at some time in the future (Government Accountability Office, 2009). But the nature of the casks means that they can be replaced and their contents transferred, making the occasional, isolated need for canister replacement manageable and consistent with the NRC’s view that aboveground storage for very long periods is technically feasible and safe.
While the various concerns cannot be ignored, the risks associated with consolidated dry cask interim storage are relatively small when compared with the risks of leaving used fuel on-site—especially when used fuel remains in storage pools and at decommissioned reactor sites. This is true even if one adopts the position of the NRC and the Energy Department that the probability of an attack on a wet pool is low: The ability for an incident to occur—whether by accident or design—and escalate rapidly is dramatically reduced if used fuel is dispersed among large numbers of robust dry casks, as opposed to being located in a common storage pool. Furthermore, moving used fuel to a consolidated interim dry cask storage regional facility will ease the eventual transition to a permanent repository. And the used fuel will be stored more safely until a permanent solution is found. While such interim storage might well further delay that process, it is nevertheless the responsible, safe, and secure way to proceed.
One final obstacle to any type of interim storage is the 1982 Nuclear Waste Policy Act itself: It legislated interim storage facilities of the kind discussed out of existence. To move to consolidated interim storage of used nuclear fuel, the Act would need to be amended or superseded by a new one. This legal obstacle to interim storage, combined with the series of political, organizational, and financial debacles besetting Yucca Mountain, has had the ironic effect of making the status quo comfortable and financially convenient for all concerned: The federal government can deal with the financial penalties without needing to resort to the cumbersome and politically fraught congressional appropriation process, while nuclear power providers are fully compensated for the costs of dealing with their used nuclear fuel.
The loser, however, is the public—that is, all of us.
Dealing with used nuclear fuel is a problem that will not go away on its own. Delay simply increases the eventual costs required to finally dispose of this radioactive material. Unfortunately, the public is the party most affected but least able to resolve the problem, while those in a position to resolve it are the least motivated to fix things.
Nevertheless, the US government should move forward. Consolidated dry cask-based interim storage is more politically feasible and financially affordable than a final permanent repository; is capable of being implemented far more quickly than a permanent repository; helps resolve the liability issues faced by the federal government; builds the storage and transportation infrastructure that will eventually be needed once a permanent repository scheme is developed and implemented; and is safer and more secure than the current storage method. Moving toward consolidated regional interim storage for used nuclear fuel does not commit the US to a particular energy future, but it does make the federal government take possession of existing used fuel and responsibly store it, thus honoring its commitments and responsibilities while a permanent solution is developed. After all, the United States should choose its future energy-supply profile unconstrained by historically unmet legal obligations and the effects of ongoing political stalemates.
Footnotes
Acknowledgements
We would like to acknowledge many useful conversations with Stephen M. Goldberg and Robert Sloan.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.