The Defence Nuclear Facilities Safety Board recommended additional monitoring and ventilation of the Hanford, Washington, under-ground tanks last fall as 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.
Central to the cleanup is the removal of 212 million litres of highly radioactive, toxic waste left from plutonium production from underground tanks.
The US federal government created Hanford in the 1940s as part of the secret Manhattan Project to build the atomic bomb. It spends billions of dollars to clean up the 1,518-squarekilometre site neighbouring the Columbia River, the southern border between Washington and Oregon and the Pacific Northwest’s largest waterway.
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.
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.”
The U.S. government spends about $2 billion US annually on Hanford cleanup – roughly one-third of its entire budget for nuclear cleanup nationally.