A $122 million waste disposal facility at the Savannah River Site is undergoing a readiness assessment and should be available for use about a year sooner than expected, the Department of Energy said Tuesday.
The DOE site in South Carolina tweeted Tuesday that it is entering the final readiness assessment for Saltstone Disposal Unit (SDU) 6, the first 30-million gallon, megavolume salt waste disposal concrete storage unit constructed at SRS. Once complete, it will be a permanent disposal unit for saltstone, a low radioactive salt waste found in the SRS storage tanks.
SDU 6 was initially slated for completion in May 2018. But, according to SRS, work will wrap up about a year early, because the original baseline work for SDU 6 included a padded schedule that allotted time for risks and other issues that never developed.
The current readiness assessment includes personnel interviews and walk-throughs to inspect the equipment and the work field where SDU operations are taking place. The RA also includes document reviews, observation of emergency preparedness drills, and other safety, health, and environmental measures.
The tweet is in line with statements from DOE SRS Manager Jack Craig in a site report last month. In the report, Craig said construction of the unit has been completed, and that it was being connected to the site’s Saltstone facility, which is comprised of other units that are used to process and store salt waste.
The Savannah River Site reported in January that SDU 6 passed a leak tightness test to ensure it would hold the radioactive salt waste. The came after a May 2016 announcement that the initial leak test had failed. To pass the second test, SRS liquid waste contractor Savannah River Remediation (SRR) installed an interior liner to protect the concrete shell from chemical degradation and achieve leak tightness.
The site’s other Saltstone Disposal Facilities include Vaults 1 and 4, along with 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. According to Revision 20 of the SRS Liquid Waste System Plan, another eight units will be needed to complete the liquid waste mission, with SDU 7 projected to be needed by fiscal 2021.
All told, about 35 million gallons of radioactive salt and sludge waste are held in more than 40 storage tanks at Savannah River. The waste, a byproduct of Cold War nuclear weapons production, is 90 percent salt waste. The salt waste is processed on site through the Modular Caustic Solvent Extraction Unit (MCU). In late 2018, the site is expected to start up the larger Salt Waste Processing Facility, which will boost waste processing from 1.5 million gallons a year to 6 million. Ultimately, the final salt waste solution is placed in the SDUs for permanent disposition.
