PNNL

Four researchers from Pacific Northwest National Laboratory (PNNL) contributed expertise to two national reports on the future of cleanup at the Hanford Site.

Matt Asmussen, Tom Brouns, Stephanie Johansen, and Leah Hare served on the technical team for the Federally Funded Research and Development Center’s (FFRDC’s) Follow-on Report of Analysis of Approaches to Supplemental Treatment of Low-Activity Waste at the Hanford Nuclear Reservation. The FFRDC report was released in January 2023 and is the subject of an in-depth review, released in May 2023 by the National Academies of Sciences, Engineering, and Medicine (NASEM).

“Management of the Hanford tank waste is one of the nation’s most daunting environmental challenges,” said Johansen. “It was fulfilling to apply expertise to solving a problem that has the potential to impact our local community for decades to come.”

The FFRDC team, led by Savannah River National Laboratory, was made up of technical experts across multiple disciplines from national laboratories and research and engineering institutions. The report was closely analyzed by a NASEM committee—with public meetings that included presentations by Asmussen and Johansen.

“Our participation was an acknowledgement of the multi-faceted expertise at PNNL related to nuclear waste management and the Hanford mission,” said Asmussen.

PNNL has helped advance the Hanford Site cleanup mission since the 1960s by providing the technical foundations for environmental remediation and waste processing approaches for the Department of Energy’s Office of Environmental Management and its contractors.

The Hanford Site is starting to treat 56 million gallons of radioactive and chemically hazardous waste currently stored in massive underground tanks. The waste will be divided into a highly radioactive fraction and a low-activity fraction for subsequent treatment. Hanford is preparing to use a process called vitrification to convert all highly radioactive tank waste and some low-activity waste into glass logs for safe long-term storage. But acknowledged capacity limits at the vitrification plant have prompted research into alternative treatment approaches for low-activity wastes—referred to as supplemental low-activity waste, or SLAW.

In the FFRDC report, Asmussen, Brouns, Johansen, and Hare used their expertise in chemistry, waste forms, and environmental policy to help assess the potential technology and approaches for treatment of the SLAW that could lead to an effective disposal strategy. Along with vitrification and steam reforming, the team analyzed various grout treatment options that would immobilize low-activity waste in a solid concrete-like form. They also compared the advantages of grout immobilization coupled with a study of possible disposal locations for the treated SLAW.

“The waste forms team was able to provide a thorough, contemporary overview of the current state-of-the-art and of the uncertainty associated with the disposal of various waste forms at different disposal locations,” said Asmussen. “This story is rarely presented at a high level, yet technically grounded, and our team was proud to present that all in one place.”

Hare agreed. “I’m proud that I was able to use my experience on the regulatory aspect of the possible treatment alternatives and on the physical attributes of Hanford Site to support research that will assist in solving one of Hanford’s most complex problems,” she said.

The NASEM committee’s final review of the FFRDC report, Review of the Continued Analysis of Supplemental Treatment Approached of the Low-Activity Waste at the Hanford Nuclear Reservation, and its recommendations for policymakers to consider were discussed at a public meeting on June 6, 2023, in Richland, Wash.