It will take until 2031 to empty and seal 16 underground waste tanks at the Energy Department’s Hanford Site near Richland, Wash. — 12 years later than the end-date DOE and Washington state set in 2010, the federal agency said late Monday in a regulatory filing.
The 16 single-shelled tanks to be emptied and closed are in Hanford’s Waste Management Area C. By Aug. 31, 2031, the tanks are to be filled with cement-like grout to prevent what radioactive waste remains inside of them from leaking, according to a tank-closure plan DOE filed with the Washington state Department of Ecology.
The closure plan is the first step in what the Ecology Department, the lead state regulator for Hanford, expects to be a months-long process of refining the cleanup schedule for the C-Farm tanks at the former plutonium production site. The state still must propose permit modifications that would allow DOE to carry out its plan, and the permit modifications are subject to two rounds of public comment.
But already, “Ecology will be concerned about an extension of that magnitude,” John Price, Tri-Party Agreement section manager for the Ecology Department, said by email Tuesday. “We’ll look carefully at DOE’s proposed schedule, to see if it can be accelerated.”
Of the 16 tanks in Waste Management Area C, DOE and its contractors have emptied 15 to the levels prescribed in the Tri-Party Agreement that governs Hanford cleanup. The waste retrieval system for Tank C-105 failed in 2015 and the agency has not yet developed a workaround.
After DOE empties the tanks of Cold War-era waste to the regulatory standard, the agency must either remove them from the site entirely or fill them up with cement-like grout to prevent the remaining waste inside from leaking out.
DOE plans to start grouting the first of four small C-Farm tanks — known as the 200 series — by April 30, 2021, according to the closure plan filed Monday. The agency will begin grouting C-Farm’s larger 100 series tanks in 2023, the plan says.
The tanks in Waste Management Area C are all single-shell containers: older and thinner vessels than newer double-shell tanks elsewhere on the site’s two tank farms. In all, there are 149 single-shell tanks and 28 double-shell tanks at Hanford. The largest hold about double the volume of an Olympic-sized swimming pool.
