Site preparation is continuing for the next large-scale Saltstone Disposal Unit (SDU) at the U.S. Department of Energy’s Savannah River Site in South Carolina, with plans to begin construction in May 2020.
According to a post Monday on the site’s Facebook page, liquid waste contractor Savannah River Remediation (SRR) has completed excavation of the location for SDU 8, a 32-million-gallon megavolume concrete structure that will permanently house radioactive salt waste once it has been processed at the site. Savannah River Remediation also completed the drain system for the unit, along with other site preparations.
Site preparation began in June. Before construction can start next May, the contractor must first complete a lower concrete layer to serve as the base of the unit and install a leak detection system, according to a DOE spokesperson at the site.
Saltstone Disposal Unit 8 will be one of several units to store salt waste at the 310-square-mile Savannah River Site near Aiken, S.C. The others include storage Vaults 1 and 4, which are already in use, along with operational SDUs 2, 3, and 5. Each of the three units consists of two tanks, all able to hold up to 2.9 million gallons of waste.
But SDU 8 will be similar to Saltstone Disposal Units 6 and 7 in being much larger than the other units. Saltstone Disposal Unit 6 began operating in August 2018 and SDU 7 is expected to begin operations in spring 2022.
Saltstone Disposal Unit 8 is expected to be ready for use by March 2023, with SDU 9 slated for completion in September 2024. The two units are being built under the same $280 million budget allocation, with about $ 4 million spent to date.
Meanwhile, SDUs 10-12 should be available sometime between April 2025 and March 2030. A firmer date for those units should surface in fiscal 2020, the DOE spokesperson said.
Beyond that, the site will need another six megavolume units to complete the SRS liquid mission. The mission encompasses treatment of more than 35 million gallons of radioactive Cold War-era waste stored in more than 40 underground tanks. About 10 percent of that volume is sludge waste and the other 90 percent is salt waste, which has been treated using a pilot system that removes cesium and other components before the salt solution is transferred for disposal in the SDUs.
That pilot project ended last month as the site prepares the larger-scale Salt Waste Processing Facility (SWPF) to begin operations in December. Similar to the pilot plant, the SWPF will remove cesium from the salt waste and transfer the remaining salt solution to the SDUs.
All told, the SRS liquid waste mission is expected to last until 2039 and cost $33 billion to $57 billion.
