The most recently completed Saltstone Disposal Unit at the Savannah River Site was completed $60 million under budget and seven months ahead of schedule.
The Department of Energy Office of Environmental Management recently authorized Saltstone Disposal Unit 9 to begin operations, completing the last step before the unit can begin to accept decontaminated salt solution.
The Office of Environmental Management set completing the unit as one of its top priorities for 2024.
Jim Folk, assistant manager for the Office of Environmental Management's Savannah River Field Office, said the units play a "critical role" in the Office of Environmental Management's effort to clean up the nuclear waste generated during the production of plutonium and tritium during the Cold War.
"These units play a critical role in EM’s commitment to undertaking one of the largest environmental cleanup efforts in the country," Folk said in a news release. "The mega-size saltstone disposal units are vital in our ability to safely dispose of legacy liquid waste and underscore DOE’s commitment to complete the SRS Liquid Waste Program."
The unit was constructed and will be managed by Savannah River Mission Completion, the liquid waste contractor at the Savannah River Site.
The SDU 9 construction project was another well executed undertaking by the team, Savannah River Mission Completion President and Program Manager Dave Olson said.
"To safely and successfully complete a construction project of this magnitude required incredible focus, collaboration and talent by the entire team," Olson said. "I am proud of the SRMC team’s accomplishment that brings us one step closer to completing our mission through this essential project."
The Saltstone Disposal Units are one of two ends of the process to dispose of nuclear waste generated during the Cold War and stored at the Savannah River Site in 51 tanks located in F and H Areas.
The waste in the tanks comes in two forms: salt and sludge. Sludge makes up around 8 percent of the volume of the tank but nearly half of the radioactivity. The salt makes up around 92 percent of the volume and just over 50 percent of the radioactivity.
The Defense Waste Processing Facility processes the sludge. Specifically, the facility vitrifies the sludge and places the final product into the storage containers. The Salt Waste Processing Facility processes the salt. During this process, high-level nuclear waste extracted is sent to the Defense Waste Processing Facility, where it is vitrified and stored in specialized containers in buildings built for that purpose.
Low-level nuclear waste, called decontaminated solution, is sent to the Saltstone Production Facility which acts as a giant concrete plant and mixes the waste with a concrete-like substance for disposal in 12 saltstone disposal units.
The first and fourth saltstone units were completed in the mid- to late-1980s. The second unit was completed in 2012 and filled in 2014. The third and fifth units were completed in September 2013. Filling of these two units began in February 2017.
The sixth unit, the first mega unit, was completed in May 2017, and it began receiving waste in August 2018.
The mega units can hold up to 33 million gallons of saltstone.
The seventh unit, the second mega unit, was completed in July 2021, eight months ahead of schedule. The eighth unit was completed three years ahead of schedule.
The 10th unit is under construction while sites have been prepared for the 11th and 12th units with mud mat construction beginning for the 11th unit this year.
