Federal Engineers and Constructors of Richland has been awarded a $10.8 million subcontract for a construction upgrade to prepare for sludge retrieval from the Hanford K West Basin.
FE&C will modify an annex attached to the K West Basin for Department of Energy contractor CH2M Hill Plateau Remediation Co., which is responsible for removing the sludge from the basin and treating it.
Radioactive sludge will be pumped from underwater, engineered containers in the K West Basin into the modified annex, where it will go into casks. The casks will be loaded onto a trailer there to be taken to central Hanford.
Hanford produced plutonium for the nation's nuclear weapons program through the Cold War, but irradiated fuel was orphaned when chemical processing to separate out the plutonium from the fuel stopped at Hanford.
The unprocessed irradiated fuel from N Reactor was stored underwater in the K East and West Basins, with the water providing shielding from radiation. In the years before it was removed, it deteriorated and mixed with dirt, sand and debris to form a highly radioactive sludge at the bottom of the basins.
The sludge has been vacuumed up and consolidated in underwater containers at the K West Basin, which is 400 yards from the Columbia River. But the sludge is planned to be moved to T Plant in central Hanford to allow environmental cleanup near the Columbia River to be completed by 2015.
The K West Annex now is a framed steel structure on a concrete foundation with metal siding and is not suitable for working with radioactive waste. But it's in an ideal location for the work.
FE&C will expand it with a reinforced concrete structure to 53 feet long and 26 feet wide. It also must be 35 feet high. A roll up door that is 14 feet wide and 16 feet high will be required to accommodate equipment and the trailer on which the cask will be loaded.
The annex will need to meet nuclear safety standards, including shielded ducts for the slurry transfer lines that are robust enough to shield workers from radiation.
The new portion of the annex will need to be seismically isolated from the existing annex, plus have protections in place to prevent a fire from spreading because of the high hazard nature of the work with the sludge.
The modified annex also will need heating, ventilation and air conditioning to allow work year round.
The work by FE&C is expected to take about a year.
"Making these modifications will help us support DOE's commitment to move this very hazardous material to a facility in the center of the site, away from the river," said Ty Blackford, CH2M Hill vice president responsible for sludge treatment, in a statement.
"It's a top priority for Hanford cleanup."
The award to FE&C also supports CH2M Hill's goal of awarding at least 49.3 percent of its work to small businesses.
The sludge casks will be stored temporarily at T Plant until a treatment method is developed and a disposal method is determined.
Once the sludge is taken to T Plant, the modified annex will be demolished along with other buildings around the K West Reactor that are no longer needed. CH2M Hill already has removed 57 support structures near the K West and K East Reactors.