Savannah River’s DWPF receives upgrades, exits outage

February 15, 2023, 9:40AMRadwaste Solutions
Savannah River’s DWPF has completed the conversion from formic acid to glycolic acid in the waste vitrification process. (Photo: DOE)

The Defense Waste Processing Facility (DWPF) at the Department of Energy’s Savannah River Site (SRS) in South Carolina has resumed operations after a completing a processing improvement that the DOE said will enable safer operations and more efficient vitrification of radioactive waste.

Operated by SRS liquid waste contractor Savannah River Mission Completion (SRMC), the DWPF uses vitrification to convert high-activity liquid waste stored at the site into a glass form suitable for long-term storage and disposal.

Acid changeover: The DOE’s Office of Environmental Management announced yesterday that the DWPF had resumed operations after an outage to remove formic acid from the vitrification process, replacing it with glycolic acid. The facility underwent two planned operational outages in the past eight months to implement the acid changeover. The second and final outage ended January 31.

Used to prepare waste sludge prior to vitrification, glycolic acid will allow for safer operations and higher production rates while maintaining chemical stability, the DOE said.

Savannah River National Laboratory performed testing that contributed to the selection of glycolic acid as a replacement for formic acid, which, along with nitric acid, was combined with sludge to neutralize the waste, reduce mercury and manganese, destroy nitrite, and modify (thin) the slurry rheology. The replacement of formic acid with glycolic acid was studied for 10 years before it was put into use, according to Jim Folk, DOE–Savannah River assistant manager for waste disposition.

Safer, faster: According to the DOE, glycolic acid significantly reduces catalytic hydrogen generation, making the workplace much safer. The change also opens other opportunities for improvement that will result in even higher production rates, the department said.

“The conversion to glycolic acid will allow higher production rates at DWPF with the added benefit of increasing the overall safety posture for the facility worker and the Savannah River Site,” Folk said. “Our objective is to improve production while continuing to safely treat the remaining waste.”

SWPF capacity: The increased production capability is expected to help DWPF keep pace with SRS’s Salt Waste Processing Facility (SWPF), which the DOE said is processing greater volumes of waste than ever before. In slightly more than two years of operation, SWPF has processed nearly 5 million gallons of radioactive salt waste and the SRMC team has already doubled the production rates demonstrated during the first year of production, according to the DOE.

The 43 active waste storage tanks at SRS currently contain approximately 35 million gallons of radioactive liquid waste produced as byproducts from the processing of nuclear materials for Cold War–era national defense, research, medical programs, and U.S. space missions.

Other upgrades: SRMC made improvements across Savannah River’s entire liquid waste program during the most recent outage, the DOE said. SWPF teams performed maintenance on multiple pumps, performed component replacements, and installed modifications to improve overall system performance.

At the Saltstone Production Facility, where decontaminated salt solution from SWPF is converted into grout, teams have rebuilt portions of the processing equipment and performed mechanical tie-ins to a recently built saltstone disposal unit.

Crews working at the site’s underground waste storage tanks used the integrated outage to move the next sludge batch into the sludge feed tank, make repairs to the tank that receives decontaminated salt solution from SWPF, and begin solids removal from the DWPF recycle receipt tank.

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