The Department of Energy’s National Nuclear Security Administration hopes to dispose of up to 34 metric tons of surplus defense-related plutonium at the Waste Isolation Pilot Plant in New Mexico using a “dilute-and-dispose” strategy.
The NNSA’s preferred disposal method is contained in the final environmental impact statement (EIS) prepared for the administration’s Surplus Plutonium Disposition Program. Notice of the EIS was published in the January 19 Federal Register.
Background: The DOE and the NNSA settled on the dilute-and-dispose strategy, also known as plutonium downblending, after the cancellation of the department’s mixed oxide fuel project in 2018. As part of that project, the NNSA was to build the Mixed Oxide Fuel Fabrication Facility (MFFF) in South Carolina to convert weapons-grade plutonium into MOX fuel for use in commercial U.S. nuclear power plants. Construction of the MFFF, however, was canceled after the NNSA estimated the facility would cost $17 billion and not be complete until 2048.
Disposition of the plutonium was required by a 1998 agreement between the United States and Russia in which each country agreed to convert 34 metric tons of surplus weapons-grade plutonium to a form that could not be returned to nuclear weapons.
According to the NNSA, the Surplus Plutonium Disposition Program EIS satisfies the administration’s obligations under the National Environmental Policy Act (NEPA) as it seeks to reduce the threat of nuclear weapons proliferation worldwide by dispositioning surplus U.S. plutonium in a safe and secure manner. Disposing of the plutonium will also help the NNSA meet its legal obligations under the 1998 agreement with Russia.
In December 2020, the agency announced its intent to prepare an EIS to evaluate the environmental impacts of the dilute-and-dispose strategy. A draft EIS was released for public comment on December 16, 2022, and the NNSA conducted three in-person public hearings and one virtual public hearing the following month. The NNSA said it has incorporated public comments, developed the final program EIS, and is committed to complying with all appropriate and applicable environmental and regulatory requirements.
The strategy: The agency’s disposal strategy includes converting pit and nonpit plutonium to oxide, blending the oxidized plutonium with an adulterant, compressing it, encasing it in two containers, then overpacking and disposing of the resulting contact-handled transuranic waste underground at WIPP. According to the NNSA, the approach would require new, modified, or existing capabilities at the Savannah River Site in South Carolina, Los Alamos National Laboratory in New Mexico, the Pantex Plant in Texas, and WIPP.
Under a no-action alternative, up to 7.1 metric tons of nonpit plutonium would be processed at either LANL or SRS. If the processing occurs at LANL, then the resulting plutonium oxide would be transported to SRS. If it occurs at SRS, then the resulting material would remain there. In both cases, the processed material would be diluted, characterized, packaged, and transported as contact-handled transuranic defense waste to the WIPP facility for disposal.
Next steps: The NNSA said it will publish a record of decision for the Surplus Plutonium Disposition Program after February 20, 2024, which will be published in the Federal Register and posted on the DOE NEPA and NNSA NEPA reading room websites, where the final Surplus Plutonium Disposition Program EIS can also be found.