In a conference call Thursday with reporters, Under Secretary for Nuclear Security Thomas D’Agostino said two of the site’s remaining 49 underground high level waste storage tanks have been cleared for final closure after a multi-year, $50 million effort by liquid waste contractor Savannah River Remediation.
Tanks 18 and 19 – located in the site’s F Area – were deemed the most vulnerable to failure and earmarked as the first to be emptied and sealed, he said.
“These tank closures will be the first DOE tanks closed nationwide since 2007, the first closed at SRS in 15 years, and some of the largest underground storage tanks closed by the department to date,” D’Agostino said.
The millions of gallons of high level waste in the tanks was generated in the 1950s and 1960s during Cold War nuclear weapons production. Material removed from the two tanks was sent to the Defense Waste Processing Facility at the site, where it was “vitrified” into glass logs sealed in steel canisters, rendering them permanently stable.
The milestone reached with tanks 18 and 19 includes final regulatory approval from the S.C. Department of Health & Environmental Control and other state and federal agencies that have signed off on a final closure plan.
Cleanup efforts have removed 99 percent of the waste from the two tanks. During the next five months, about 70 workers will haul up to six truckloads of concrete per hour to eventually pour more than 3 million gallons of specially made grout to fill and permanently close the tanks.
Although it took many years to reach closure for tanks 18 and 19, future closures are expected to move more rapidly, with the next group of four tank closures occurring in 2014-15. The remaining single-walled tanks are expected to be closed by 2022, and all tank closures are to be completed by 2028.
Originally, there were 51 underground tanks at the site’s H and F areas. Two were closed in the 1990s, and the remaining tanks contain 33 million gallons of decaying waste. Twelve tanks are leaking, but the areas are contained to prevent material from entering the environment.
About 3,000 canisters of vitrified high level waste processed during the past decade remain in storage at SRS. Some of the material was earmarked for permanent burial in Nevada’s Yucca Mountain repository – a project that has since been scrapped by the Energy Department.