Tank Puzzles Hanford Officials But ‘Crust’ Poses No Imminent Danger, They Say

The Department of Energy admitted Monday it can’t figure out why the level of a chemical “crust” in a notorious Hanford underground tank has risen 2 inches over the past year.

The federal agency declared an “unreviewed safety question” for Tank 101SY, kicking off a safety analysis that will attempt to find a cause and suggest a solution, department spokesman Guy Schein said.

There is no imminent danger to workers or the public, Schein and other Energy Department officials said. “It is probably more in the realm of a paperwork exercise,” Schein said.

Tank 101SY, a newer double-shelled tank, contains radioactive wastes from decades of plutonium production at the Hanford Nuclear Reservation. In the past, the tank has “burped” significant amounts of hydrogen gas, which possibly could have exploded.

In 1993, a mixer pump was installed to stir the tank’s contents to control the buildup of hydrogen gas.

But in the past year, the surface level of the wastes has risen about 2 inches, Schein said. The surface is a chemical hard “crust” atop radioactive liquids.

The safety question “simply means the tank is performing differently than was analyzed in a safety analysis,” said technical adviser Steve Wiegman. “This acknowledges that. We’ll now go into the tank to determine what’s causing that and if additional controls are needed.”

Lockheed Hanford Co., the contractor in charge of cleaning up Hanford’s tanks, will develop a plan by March 20 for sampling the tank’s contents and making estimates of additional costs, said Mike Royack, acting director for tank waste remediation.

Royack and Wiegman said there is little concern about threats to safety because the mixer pump has worked as intended to prevent gas accumulations.