YAKIMA, Wash. — Underground tanks that hold a stew of toxic, radioactive waste at the nation’s most contaminated nuclear site pose a possible risk of explosion, a nuclear safety board said in advance of confirmation hearings for the next leader of the Energy Department.
tate and federal officials have long known that hydrogen gas could build up inside the tanks at the Hanford Nuclear Reservation, leading to an explosion that would release radioactive material. The Defense Nuclear Facilities Safety Board recommended additional monitoring and ventilation of the tanks last fall, and federal officials were working to develop a plan to implement the recommendation.
Federal officials have said six underground tanks at the site are leaking into the soil, threatening the groundwater, and technical problems have delayed construction of a plant to treat the waste for long-term safe disposal.
Those issues are likely to come up during confirmation hearings next week for Energy Secretary-nominee Ernest J. Moniz. The fears of explosion and contamination could give Washington and Oregon officials more clout as they push for cleanup of the World War II-era site.
Central to the cleanup are the removal of 56 million gallons of highly radioactive, toxic waste left from plutonium production from underground tanks. Many of the site’s single-shell tanks, which have just one wall, have leaked in the past, and state and federal officials announced in February that six such tanks are leaking anew.
In addition to the leaks, the board noted concerns about the potential for hydrogen gas buildup within a tank, in particular those with a double wall, which contain deadly waste that was previously pumped out of the leaking single-shell tanks.
“All the double-shell tanks contain waste that continuously generates some flammable gas,” the board said. “This gas will eventually reach flammable conditions if adequate ventilation is not provided.”