In the last substantial cleanup of highly radioactive waste in an area of the U.S. Dept. of Energy’s Hanford nuclear-waste site that was once the core of nuclear-reactor fuel production for atomic bombs, crews will use a gantry crane and grout to move and seal a vault and tank weighing 1,700 tons. The pick, part of the remediation of Hanford's former "300 Area" complex of hundreds of production buidings, will be the largest ever for transport and burial at the site's waste disposal facility.
Washington Closure Hanford, a joint venture of URS Corp., Bechtel National and CH2M Hill Cos., is responsible for demolishing 328 contaminated buildings, cleaning up 560 waste sites in the 1.5-sq-mile area near the Columbia River, placing two plutonium production reactors and one nuclear facility in interim safe storage, and operating the waste-burial site.
Starting in late October, Richland, Wash.-based Phoenix Enterprises NW will begin work on a $19-million demolition subcontract, part of Washington Closure’s larger $2.3-billion River Corridor closure project for DOE. The firm and its subcontractors will remove a vault and two tanks from the area's 340 building, which received wastes from 300 Area research laboratories during the 1950s and 1960s. The tanks have been emptied of liquid waste and will be filled with the lowest-density grout possible, a yet-to-be-determined formula that provides strength while meeting shipping requirements, according to site cleanup officials.
“At 1,700 tons, the grout-filled container will be the heaviest item we have transported and shipped to [the burial site] for disposal,” says Tom Kisenwether, 300 Area subcontracts manager for Washington Closure.
Charlie Blankingship, Phoenix project superintendent, says the difficult part will be a high crane lift in a limited-access area while simultaneously making sure shielding remains in place, to keep any contamination from spreading.
Another tricky challenge will be the removal of the two reactors, officials say. The TRIGA Reactor in the 308-A Building weighs about 250 tons and is already encased in a concrete bio-shield; it will fit inside a custom-fabricated steel-box container for disposal. Removing the 350-ton Plutonium Recycle Test Reactor from the 309 Building, will require Phoenix to cut the structure away from its base and encase it in a bio-shield before it can be lifted into a steel container for transport to the dump site. Added shielding grout and a polyurea coating will bring the structure's end weight to about 800 tons.
Even among many non-traditional cleanup challenges at Hanford, site officials say the disassembling and removal of a reactor of this size—let alone the transportation of it—is a first at the location. “The 309 reactor removal is the most technical [in the process] in that it requires partial disassembly of the reactor,” Kisenwether says.
Crews will remove an estimated 12,626 tons of contaminated material from two other buildings in the 300 Area, as well as 22,000 tons of contaminated soil from locations near the 340 Building.
“The discovery of highly contaminated soils under the 324 Laboratory underscores the unpredictability of remediating these legacy facilities and waste sites,” says Mark French, DOE federal project director for the River Corridor.
Five companies bid on the work and were all were technically qualified, according to Washington Closure. Phoenix was the low bidder. The firm's team of subcontractors includes Barnhart, Memphis; Carter Environmental Services, Nampa, Idaho; Cutting Edge Services Corp., Batavia, Ohio; the Hayward, Calif., office of LVI Environmental Services; Meier Enterprises, Kennewick, Wash.; and MetalFab Inc., West Richland, Wash.
The entire project should be completed by September 2012.