What went wrong with US plutonium disposition

By Alexander Lubkin | April 24, 2018


During the Cold War, the United States and the Soviet Union manufactured enormous quantities of plutonium for use in nuclear weapons. When that era ended, the United States and the newly formed Russian Federation began to reduce their nuclear arsenals. Both nations possessed large stockpiles of plutonium—a problem that posed both a sustained threat to the environment and a risk of future nuclear weapons proliferation. In 2000, the United States and Russia pledged to dispose of their excess plutonium in order to mitigate the security concerns, safety risks, and storage costs. They signed the Plutonium Management and Disposition Agreement, which requires each country to dispose of at least 34 metric tons of weapons plutonium.

Unfortunately, the agreement failed to solve the excess plutonium problem. Eighteen years later, the United States has been unable to develop a successful strategy to safely, affordably, and permanently dispose of plutonium from dismantled nuclear weapons, despite a high degree of industrial capability and technical expertise. Why has the United States been unable to either implement its obligations under the disposition agreement or execute its own policy? And how can the Plutonium Disposition Program finally become effective?

A messy history. Plutonium is produced in nuclear reactors by the transmutation of U-238 into Pu-239, a reaction initiated by exposure to neutron radiation. During the Cold War, the Hanford Site in Washington State produced the majority of US plutonium through this process, followed by chemical processing to remove the small quantity of plutonium from the remaining uranium and fission products.

The First and Second Strategic Arms Reduction Treaties, signed in 1991 and 1993, greatly reduced US and Russian weapons deployments, but enlarged their fissile material stockpiles and led to a surplus of weapons-usable plutonium in the United States and the newly formed Russian Federation. After signing the disposition agreement with Russia, the United States undertook a massive enterprise to dispose of its weapons-usable plutonium.

There are processes to largely prevent plutonium from being recovered and used in the future, despite the difficulty in disposing of the material. Initially, the United States pursued two approaches: A mixed-oxide or “MOX” fuel—made of plutonium oxide and uranium oxide—which could fuel nuclear power reactors and would become irradiated in the process. The second approach was “can-in-canisterdilution and immobilization of plutonium in “pucks” of crystalline ceramic that could subsequently be placed in canisters filled with vitrified high-level waste. In both of these disposal methods, the plutonium is surrounded by an intense radiation field from the fission products, which protects it from retrieval by increasing the difficulty of access. The United States eventually decided to abandon the immobilization option to reduce costs, thereafter relying solely on the MOX option. After two decades of technical work, years of construction on the Mixed Oxide Fuel Fabrication Facility and related facilities in Aiken, South Carolina, and billions of dollars spent, the project remains incomplete and mired in political controversy. The current schedule for disposal suggests completion several decades from now, with the total cost of plutonium disposal likely in the tens of billions of dollars.

A comprehensive review and analysis of decades of government, non-governmental, and academic reports, as well as interviews with several key participants in the Plutonium Disposition Project, illustrates an organizational failure to develop a realistic understanding of the technical disposal options and the means to execute them. The current state of affairs is not the result of explicit decisions, but rather of a drift from one option to the next as evolving technical viability and costs were not recognized. The failure of the US Plutonium Disposition Program can be attributed to the following root causes.

An inflexible standard. Policy makers relied too heavily on a metric known as the “spent fuel standard,” which was recommended in a 1994 National Academy of Sciences report. The report served as a roadmap for a significant portion of the plutonium disposition effort, and the standard was designed to compare various disposal strategies to the spent MOX fuel approach based on the amount of self-protection afforded by the radiation from incorporated fission product elements. (These fission products emit harmful gamma radiation that impedes access and retrieval of the incorporated plutonium.) Reliance on this single metric led the Plutonium Disposition Program to discount other possible barriers to retrieval, such as burying plutonium in deep boreholes, which may have been equally effective in protecting the environment and preventing the material from being used in future nuclear weapons. Requiring a radiation barrier, as recommended by the 1994 report, added substantial complexity to the handling of plutonium, which on its own does not emit highly-penetrating radiation. The spent fuel standard also prevented policymakers from considering disposal methods that took advantage of intrinsic material properties, such as methods that incorporate plutonium into the structure of the waste material and mitigate the nuclear, physical, and chemical impact on the environment. The decision-making process focused too heavily on meeting the spent fuel standard and prevented the Energy Department from pursuing alternative approaches that were equally defensible yet relied on alternative methods of disposal.

Spiraling costs. When the United States began its disposal program, policymakers believed the technical challenges were minimal. Design of the Mixed Oxide Fuel Fabrication Facility, which would become the primary US facility for fabricating MOX fuel, was based on the already-operating French MELOX plant. The MELOX plant is similar to the South Carolina facility in that it converts uranium oxide and plutonium oxide feedstock into MOX fuel pellets. The US plant was initially intended to replicate the French plant, but as a consequence of national differences in contracting, procurement, regulations, and feedstock material, the scope of the US project quickly shifted to designing a first-of-a-kind facility. Seemingly minor changes, such as the switch from metric to imperial units and from French to US pipe sizes, caused cost increases and delays. Certain standard items could not be shipped from France because federal procurement rules in the United States require components to be sourced domestically. The lack of a nuclear industrial base in the United States, in contrast to the well-developed industry in France, required training new workers and establishing new contractor relationships. These problems were compounded by differences in regulations under the US Nuclear Regulatory Commission and the French Nuclear Safety Authority. French nuclear regulators seek to minimize the overall risk associated with a facility, while the Nuclear Regulatory Commission mandates predefined standards and tolerances for specific components. These discrepancies required changes to the originally planned US design, for instance by adding additional radiation shielding and greater automation. The result was a vastly over-budget and off-schedule project.

A communication breakdown between technical experts and government contractors added complexity and cost to the Plutonium Disposition Program. The Energy Department did not consult with outside experts or communicate its need for alternative disposition approaches to the broader scientific community, which could have led to better and more efficient solutions. For example, after the Energy Department scrapped a plan to provide clean feedstock plutonium for the MOX fabrication process, the Mixed Oxide Fuel Fabrication Facility needed to include a process called aqueous polishing. This is an essential step that removes plutonium feedstock impurities, such as alloyed gallium, prior to conversion to plutonium oxide. While the fuel fabrication facility did eventually incorporate aqueous polishing, identifying the challenges involved sooner could have helped avoid additional costs and delays.

Inadequate funding. Inadequate and sporadic funding added another dimension of complexity to the Plutonium Disposition Program. Congress dictates funding for the Energy Department and by extension the MOX project. While large-scale projects require a ramp-up and drawdown funding pattern, Congress is typically resistant to year-on-year cost variations; congressional support for large projects can be transient for other reasons as well. During the initial construction phase of the MOX facility, the funding ramp-up allocated was inadequate for capital expenses, and as a result baseline costs consumed a significant portion of the budget.

Over time, uncertainty regarding the Plutonium Disposition Program—and potential alternatives—resulted in Congress maintaining low funding levels. The problem continues to this day, with various reports demonstrating that lower, constrained funding levels will increase life-time costs by billions or even tens of billions of dollars.

Meanwhile, the shifting priorities of consecutive presidential administrations also fueled the funding problem. The Clinton administration chose to pursue a dual-track approach, with development work on both the MOX and the can-in-canister approach. The George W. Bush administration, though, converted to a single-track (MOX only) approach as part of a plan to balance the budget. The Obama administration was interested in pursuing alternative disposal options, but the powerful Congressional delegation from South Carolina, where the Mixed Oxide Fuel Fabrication Facility is located, pushed for continued construction on the plant. This conflict slowed the project and hindered development of any approach.

Finally, an additional major impediment to securing adequate funding was the Energy Department’s own competitive appropriations process, which dictated that other projects had to lose funds in order to increase funding for the Plutonium Disposition Program.

A policy mismatch. The MOX strategy ran counter to the US national strategy favoring an open nuclear fuel cycle. Spent fuel is treated as waste in an open cycle, whereas in a closed cycle it is reprocessed to extract plutonium. The United States established a moratorium on commercial closed fuel cycles in 1977 due to nonproliferation concerns—the risk being that in a closed cycle, once plutonium is removed from the spent fuel, it is a weapons-usable material. (In contrast, the uranium used in nuclear power reactor fuel would require additional processing to be used in weapons.)

Nations that employ closed fuel cycles possess the facilities and technical knowledge to convert plutonium and uranium oxides into mixed-oxide fuel. The United States did not embrace closed fuel cycles; as a result, it lacks the infrastructure and talent pool to properly convert plutonium into commercial fuel, as it plans to do at the South Carolina facility. The lack of experience with closed fuel cycles, and absence of any national plan to further pursue them, contributed to insufficient political will to complete the project, and minimal economic incentive to invest in new technologies.

The way forward. The US program ultimately failed because of organizational and communication issues, a waste standard that constrained disposition options, fundamental misunderstandings of the technology by those in policy-making positions, insufficient understanding of the challenges of adapting a French plant design in the United States, an underdeveloped contractor base, political issues that affected funding, and the fact that the disposition program did not align with the national open nuclear-fuel strategy.

So what should come next for the Plutonium Disposition Program? Two recent Energy Department reports—the 2012 Blue Ribbon Commission on America’s Nuclear Future report and the 2016 Integrated Waste Management report on Consent Based Siting—point the way. Both reports recommended that the US Government create a new nuclear waste management organization.

The creation of a new waste management organization would indeed be an effective start, but not enough on its own. The United States needs a comprehensive national strategy for nuclear waste disposition that takes into account the mistakes outlined above. A broad-based, reorganized nuclear waste disposition program should combine the existing plutonium disposition program with other US nuclear waste disposal projects into a unified national strategy. The program should be implemented by a single-purpose organization focused on disposal of all of the nation’s nuclear waste and weapon disposition material, including from both civilian energy and defense activities.

Together, these steps will alleviate the security and environmental risks posed by the continued storage of spent nuclear fuel, mitigate the risk of proliferation by reducing the US stockpile of weapons-usable plutonium, and encourage Russia to follow through with its own plutonium disposition plans.

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Topics: Voices of Tomorrow



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