The U.S. Department of Energy will likely need an updated strategy sooner than anticipated for temporary storage of treated radioactive liquid waste at the Savannah River Site in South Carolina, according to the DOE Inspector General’s Office.
The department’s Office of Environmental Management (EM) did not properly assess the reliability of its strategy to store waste at the 310-square-mile site near the city of Aiken. Deputy Inspector General for Audits and Inspections Michelle Anderson wrote in a Feb. 19 letter to Assistant Energy Secretary for Environmental Management Anne Marie White. As a result, more storage space will likely be needed before the expected date of 2029, according to a 16-page audit report that accompanied the letter.
Roughly 35 million gallons of liquid waste is stored in more than 40 underground Cold War-era tanks at the Savannah River Site. Sludge waste accounts for 10 percent of that volume; the Defense Waste Processing Facility (DWPF) converts the material into a glassy, less harmful form suitable for interim storage at SRS. The treated waste is placed into Glass Waste Storage Buildings (GWSB) 1 and 2. The Energy Department contemplated building a third facility, but nothing came of those discussions.
Since October 2016, liquid waste contractor Savannah River Remediation (SRR) has been creating extra storage space in GWSB 1 by double-stacking waste canisters. That required reconfiguring the waste storage slots to accommodate canisters to be stored on top of each other. The method has doubled the number of canisters the building can house, from 2,254 to 4,508. To date, 553 canisters have been double-stacked.
The method costs $3 million a year, and is expected to last another six or seven years. All told, the project is expected to cost about $22 million.
The Inspector General’s Office said the Defense Waste Processing Facility is expected to produce 8,170 waste canisters in its lifetime, including roughly 4,200 generated to date. With double-stacking in Building 1, and normal storage in Building 2, the site will still need storage space for at least 1,310 more canisters.
The EM office was expected to offer a solution by 2029, but the report states one may be needed earlier because the double-stacking method has not been fully vetted. Talks have previously been held on double-stacking canisters in GWSB 2, but there has been no decision to proceed.
While the maximum capacity in GWSB 1 is 4,508 spaces, that is a best-case scenario. Modifications have only been made to one area of the building, and it is still unclear if the rest of the storage structure can successfully be altered for double-stacking. “There are uncertainties associated with how many of the standard canister storage positions can actually be modified to the double stacked configuration and whether the radioactive canisters will remain double stacked until final shipment to a yet-to-be-determined permanent off-site Federal repository,” the IG report says.
The inspector general added that an updated method could require workers to move canisters that have already been double-stacked. If that happens, “the workers will be unnecessarily exposed to the health and safety risks inherently associated with each additional movement of the canisters,” officials wrote.
The agency recommended Environmental Management determine how many standard canister positions can be employed for double-stacking and if the canisters will remain double-stacked until they are shipped to a federal repository for permanent disposal. Also, DOE needs to determine how it will store the remaining 1,310 canisters, the report says.
In a response attached to the report, DOE said it is already addressing the issues raised by the inspector general. For starters, double-stacking is working so well that the department believes it should be able to max out storage in GWSB 1. Establishing additional storage for waste canisters will be one of the requirements in the new Savannah River Site liquid waste contract.
Establishing additional storage for waste canisters was supposed to be a requirement in the new Savannah River Site liquid waste contract. Savannah River Remediation was supposed only be on the job through March 31 of this year, but DOE announced Tuesday it was canceling the solicitation for a new contract. That keeps AECOM-led SRR in place for the foreseeable future.
