The Department of Energy’s Hanford Site in Washington state needs to be better prepared to cope with additional failure of single-shell tanks holding radioactive wastes, according to the agency’s Office of Inspector General.
That is a key takeaway from a report, dated Sept. 30 and recently posted online.
If many existing underground tanks fail there might not be enough space available in double-shell tanks to accommodate the waste, the OIG said in the report.
As of this past February, double-shell tanks have about 5.83 million gallons of available space. But only 2.5 million gallons of this space is usable to store waste from future potential tank leaks because some of this space is restricted due to chemical hazards, according to the report.
There is enough space available if one double-shell fails, but if more than one goes down before the Waste Treatment Plant starts operating in late 2023, “there would not be enough available space to address the leaks without impacts to other mission elements” such as single-shell tank retrievals.
Also, the 6.5-mile waste pipeline that runs between the Hanford Site 200 West Area and the 200 East Area, is not in service. The Office of Inspector General said DOE needs to fix this cross-site transfer system and draft plans to cope with more double-shell tank failures.
“Until the issues we identified are addressed, the Department faces an increased risk to the safe storage of its tank waste while the cleanup mission remains incomplete,” OIG said.
The DOE and contractor Washington River Protection Solutions are in charge of about 56 million gallons of liquid radioactive waste. The material, left over from decades of Cold War era plutonium production, is stashed in 177 underground tanks.
Of that number, 149 are single-shell tanks built between 1943 and 1964 and designed to have only a 20-year lifespan. The other 28 are double-shell tanks built between 1968 and 1986 that will be needed to hold the waste until at least 2047.
More than a third of the single-shell tanks at Hanford are assumed to be leaking. In January 2019, the DOE provided information to the Office of Inspector General saying it has examined 84 single-shell tanks and found 24 had water intrusion ranging from 12 to 1,000 gallons. This expands the amount of liquid waste within a tank and makes it more difficult to determine if a tank is leaking, according to the OIG report.
The department has put together an expert panel to study the tank integrity issue at Hanford, OIG said.
