The primary obstacle to the Department of Energy’s plan for diluting and disposing of surplus plutonium deep underground in New Mexico is scaling up the technology and workforce to do the job, a National Academies panel said Thursday in a long-awaited final report.
At the same time, the congressionally chartered group warned, DOE’s semiautonomous National Nuclear Security Administration (NNSA), and its Office of Environmental Management should immediately negotiate an accord one another to reserve space for their separate shares of surplus plutonium in the Waste Isolation Pilot Plant (WIPP) near the city of Carlsbad.
“[T]he DOE-NNSA Administrator, in consultation with the DOE-[Environmental Management] Assistant Secretary, should prioritize and reserve Land Withdrawal Act capacity in WIPP for the full amount” of dilute and dispose waste, the committee wrote in its report.
Including the NNSA’s 34 metric tons of surplus plutonium, about 48 metric tons of the fissile material could be headed to WIPP over the next 30 years, the committee wrote. If the Energy Department isn’t careful, the challenges of scaling up the Environmental Management office’s small-scale demonstration of the dilute-and-dispose approach could wipe out the savings the agency projects from using the method.
“This is not trivial,” Robert Dynes, the former University of California president who chaired the group, said in a public webcast Thursday. “The committee urges, among other things, that the DOE develop [a] technology development plan to seek new, faster and cheaper and safer ways to dilute and dispose. The implementation challenges that are not addressed could result in even longer timelines and increased costs.”
A key step of the dilute and dispose process is turning plutonium metal into plutonium oxide at the Los Alamos National Laboratory’s Plutonium Facility (PF-4). The New Mexico site has needed about 80 people for the pilot-level diluting done at PF-4 so far; it will need almost 300 for a production-level dilute and dispose program, acording to the committee’s report.
Apart from that, the NNSA will also have to be able to securely transport the higher volumes of plutonium between several facilities and finally on to WIPP, the panel said.
The NNSA has said its share of dilute and dispose would cost about $20 billion to build and operate from 2028 until about 2050. That compares with about $50 billion over a similar time frame for the canceled Mixed Oxide Fuel Fabrication Facility at the Savannah River Site, which was going to turn the agency’s 34 metric tons of surplus fissile material into commercial nuclear reactor fuel. The NNSA terminated the project in 2018, after a protracted fight with the state of South Carolina and Mixed Oxide Fuel Fabrication Facility contractor MOX Services.
To help develop new dilute-and-dispose technology, whatever it might be, the committee suggested DOE create an independent technical group to advise the program over its planned 30-year span.
Besides the 34 metric tons of plutonium pits, metal, and oxide for which the NNSA is responsible, the Environmental Management office is disposing of about 6 metric tons of non-pit plutonium using a dilute-and-dispose line already operational at Savannah River Site’s K-Area. The Energy Department might also dilute and dispose of another 7 tons of plutonium pits, and another ton or so of non-pit material that would be immobilized by Savannah River’s Defense Waste Processing Facility. The National Academies Panel lumped this roughly 48 metric tons of plutonium together in its report.
Dilute and dispose, formally known in the NNSA as the Surplus Plutonium Disposition program, involves converting surplus plutonium into plutonium oxide at Los Alamos’ PF-4 Plutonium Facility, then transporting it to Savannah River to be blended with a classified, inert material called stardust. The resulting mixture is what DOE would bury at WIPP, which the Environmental Management office operates.
The NNSA is procuring components including gloveboxes for the program now. The agency will initially run two dilute-and-dispose glove boxes at Savannah River Site’s K-Area, with a third in reserve. The program has a roughly $80 million budget in 2020.
The approach has a host of issues and obstacles to navigate that technical ingenuity will not resolve — although the National Academies panel did say the plan is technically and environmentally feasible.
Chiefly, WIPP is running out of time and running out of space. There is more transuranic waste — mostly plutonium-contaminated matter created during nuclear weapons production — planned for disposal than the facility has space to accept.
That is true even after the New Mexico Environment Department approved DOE’s plan to exclude the volume of waste packaging from the tally of filled space. The NNSA’s plans to produce plutonium pits, 10 a year in 2024, 20 a year in 2026 and 80 a year or more in 2030 and beyond, would in 50 years create enough transuranic waste to eat up about half the remaining 110,000 cubic meters of usable space left underground at WIPP. Meanwhile, other Energy Department facilities will still be shipping their own waste to New Mexico.
It would also take buy-in from Congress, which would have to change federal law, and the New Mexico Environment Department, which would have to approve modifications to WIPP’s hazardous waste permit, to expand the mine beyond its statutory cap of about 175,000 cubic meters, and maintain operations to 2050. WIPP is officially scheduled to stop accepting waste in 2024 and certify final closure in 2034, but DOE wants the facility to accept waste for decades more.
The whole plan “changes the nature and function of the United States’ only operational deep geologic waste repository,” and “represents a substantial technical and ‘social contract’ change for WIPP and the State of New Mexico,” the National Academies panel wrote in its final report.
