The National Nuclear Security Administration’s early-stage plan to dilute and dispose of 34 metric tons of surplus plutonium in the Waste Isolation Pilot Plant (WIPP) is technically viable, according to an April 30 release from the National Academies of Sciences, Engineering, and Medicine.
Background: In 2014, the Department of Energy produced early-stage plans to disposition diluted surplus plutonium transuranic (DSP-TRU) waste by diluting it at the Savannah River Site in South Carolina, then transporting it to WIPP in New Mexico for disposal. This “dilute-and-dispose” plan carries an estimated cost of $18.2 billion over more than 30 years.
A National Academies report, "Review of the Department of Energy’s Plans for Disposal of Surplus Plutonium in the Waste Isolation Pilot Plant" (review report), finds that nearly all of the plan’s individual processes and steps have been demonstrated successfully in the past by the DOE. The plan utilizes shared equipment and resources from other DOE efforts, employs well-established transportation programs, and references previous successful emplacements of similar waste in WIPP.
Environmental impacts: According to the National Academies, disposing of DSP-TRU waste at WIPP would fundamentally change the nature of the geologic repository, which raises social, environmental, and technical questions. If unanswered, these questions translate to vulnerabilities that would need to be resolved for the plan to be viable. The review report recommends that the DOE implement a new programmatic environmental impact statement to consider the full environmental effect of National Nuclear Security Administration’s plan on WIPP. It also recommends that the Environmental Protection Agency, the DOE, and New Mexico develop a mutual strategy for vetting the effects of the plan, in addition to reinstating the Environmental Evaluation Group, an independent technical group overseeing the protection of public health and the environment on behalf of New Mexico and its citizens.
Security plans: Still under development. The review report says that periodic reviews of the plan’s security arrangements by a team of independent technical experts should be required until its classified aspects are completed and implemented, adding that DSP-TRU waste is not like other transuranic nuclear waste streams at WIPP, and standard operating procedures may not be adequate for securing the waste. “With sufficient mining expertise (which is becoming more common) and resources, non-state or third-state actors could retrieve emplaced DSP-TRU waste during the post-closure period with its absence left undetected,” the review report states. The review report also recommends that the DOE periodically update its security assessments, given the long duration of the program.
Program execution challenges: While none threaten the plan’s technical viability, execution challenges to the dilute-and-dispose approach could be addressed through improved project plans and consistent funding from Congress. Challenges include scaling up current operations to a system that can generate, transport, and dispose of DSP-TRU waste on schedule, or maintaining infrastructure and a workforce that can last the 30-year span of the project. These could lead to extended timelines and increased costs, the National Academies said. The review report notes that the NNSA’s plan also spans multiple DOE sites, offices, and functions without clear crosscutting leadership.
International agreements: The review report recommends that the DOE clarify its intent for International Atomic Energy Agency monitoring and inspections prior to the placement of waste at WIPP. Under the Plutonium Management and Disposition Agreement (PMDA) between the United States and Russia, the surplus plutonium was to be converted to mixed oxide nuclear fuel. The DOE’s dilute-and-dispose approach, however, is not recognized by PMDA, which also requires international monitoring and verification. Yet the DOE’s plans allow for monitoring and verification to remain under development.
WIPP capacity: Emplacing the full amount of DSP-TRU waste in WIPP will test its physical and statutory capacity, according to the National Academies. WIPP is the nation’s only operational deep geologic repository for nuclear waste, and the review report says that capacity at WIPP should be treated as a valuable and limited resource by the DOE. The National Academies recommends that the NNSA administrator, in consultation with the DOE assistant secretary for environmental management, reserve capacity in WIPP for the full amount of DSP-TRU waste.