The Office of Inspector General (IG) of the Department of Energy is raising concerns about the ability of the department to safely store radioactive waste in underground tanks at the Hanford Site until its cleanup mission there is complete. Specifically, the IG said that the tanks, which include 149 single-shell tanks (SST) and 28 double-shell tanks (DST), have deteriorated over time and there may not be enough space in the DSTs to accommodate waste from failed tanks.
Aging tanks: Hanford’s underground waste tanks were built to hold liquid waste resulting from plutonium processing at the site in southeastern Washington. About 56 million gallons of mixed radioactive and chemical waste remains stored at different tank farms on the site.
The SSTs, which were built between 1943 and 1964, are well past their design life and do not meet current regulatory requirements. The DSTs, meanwhile, were built between 1968 and 1986 and have a carbon-steel inner tank with a separate steel liner surrounding it.
While the DSTs meet current regulations, in 2012 a DST was found to be leaking waste into the annulus space between the inner tank and its liner. While waste from that tank was transferred to another DST, the DOE has identified similar tanks that may be at risk of leaking from corrosion, according to the IG. The DSTs will need to contain waste until at least 2047.
Oversight troubles: The IG said that it attributes the problems identified in its report to weaknesses in the DOE’s oversight of tank operations. Specifically, the IG said that the DOE has not adequately prepared for multiple DST failures and has not maintained the operability of a system used to transfer waste between Hanford’s 200 West Area and 200 East Area. The areas are separated by more than 6 miles.
DOE response: In response to the IG'S report, William “Ike” White, DOE senior advisor for environmental management, said that the DOE “has taken significant measures in its oversight and management of tank waste at the Hanford Site, including the formation of a Tank Integrity Expert Panel, performing tank integrity evaluations, developing technology, and performing major upgrades to tank farm systems.”
DOE management also concurred with the recommendations of the IG, including developing a plan to address and evaluate the effects of additional DST failures, ensuring the ability to transfer tank waste from the 200 West Area to the 200 East Area, and updating its emergency guidance for pumping waste from failed DSTs.