The Government Accountability Office says there is an opportunity for the Department of Energy to balance the cost and risks posed by 149 single-shell tanks containing radioactive waste at the Hanford Site in Washington state.
A section a Jan. 29 GAO report, on growing liability costs for DOE’s Office of Environmental Management, said the agency could better control costs by determining which Hanford tanks pose the greatest threat to groundwater.
About 56 million gallons of radioactive liquid waste, generated by decades of plutonium production at Hanford, is stored in 177 tanks. In addition to the 149 single-shell tanks, some of which date to the 1940s and have developed leaks, another 28 newer tanks have two shells. The inner shell holds the waste and the second shell serves as a containment barrier.
Just 58 of the single-shell vessels are responsible for 90 percent of the groundwater contamination linked to Hanford’s tank farms, according to a 2015 report commissioned by the Energy Department. A 30-year state-federal agreement essentially calls for removal of 99 percent of waste from Hanford’s single-shell tanks. However, Washington state regulators say this was only a “temporary requirement” until DOE determined how much waste could safely be left in the tanks.
The Energy Department has not completed its evaluation, the GAO said in the report.
The Office of Environmental Management drafted an internal proposal in August 2017 to retrieve waste from the higher-risk tanks, and allowing more waste to be left in other single-shell tanks “could potentially save billions of dollars,” the report says. It was part of general theme in the report where GAO urges the Energy Department to prioritize the most pressing risks.
The Tri-Party Agreement, which governs environmental remediation at Hanford, says the Energy Department must remove as much tank waste as technically possible from the single-shell tanks.
It is difficult to say how many single-shell tanks have leaked because there is not a way to get beneath the tanks to check, but the Energy Department and its contractors believe about 67 have leaked into the ground, based on liquid levels and other indicators, a DOE spokesperson said Wednesday.
So far, about 7.5 million gallons of pumpable liquid has been moved from single-shell to double-shell tanks, the spokesperson said.
Ultimately, much of the waste from Hanford’s tank farms will be pumped into the Waste Treatment Plant and converted into a stable glass-like substance for disposal. The Energy Department is also considering alternative options for some of the material, such as grouting being tested in the Test Bed initiative at the nearby Perma-Fix Northwest plant.
