Hanford prepares to empty waste from single-shell tank

Washington River Protection Solutions (WRPS) is preparing to begin waste retrieval from Tank AX-101 at the Department of Energy's Hanford Site near Richland, Wash. WRPS is the tank operations contractor at Hanford.

AX-101 was one of 149 single-shell underground carbon steel tanks built to store radioactive and chemical waste from the production of weapons plutonium at the site. To reduce the risk of leaks, the DOE is transferring waste from Hanford's older single-shell tanks to newer double-shell units. A total of 28 double-shell tanks were built at Hanford between 1968 and 1986.

Holding approximately 373,000 gallons of solid, salt-based waste called saltcake and sludge-like waste, AX-101 will be the last of the four 1 million-gallon tanks in the AX Tank Farm and the 21st single-shell tank at Hanford to have its waste retrieved and moved to double-shell containers. It is expected that the retrieval of waste from AX-101 will take between one and two years.

Uneven waste: According to the DOE's Office of Environmental Management, workers this summer installed the last of three extended-reach sluicers in the tank that will spray water on the waste to break it down before it is pumped out.

Video images from cameras lowered into the tank before the last sluicer was installed showed the waste level was uneven, ranging from about 11 feet deep to nearly 14 feet. To avoid submerging the sluicer in about two feet of saltcake waste on the deeper side of the tank, which would have potentially plugged its nozzles, workers modified a high-pressure washing system to make a hole in the saltcake waste for the sluicer nozzles to fit.

The sluicers, along with a slurry pump and other support equipment, are installed in several tank risers. During retrieval, workers will operate the equipment remotely from a nearby control trailer.

Quote: "We are excited to be nearing completion of a long preparation and installation process for this tank," said Peggy Hamilton, single-shell tank retrieval and closure manager for WRPS. "The team will finish installing equipment and will thoroughly test it before starting to retrieve waste from the tank."