Demolition of one 102,000-sq-ft facility amid many others on the 586-sq-mile Hanford nuclear waste site may seem minuscule, but not when the facility contains some of the world’s highest radiation levels.
Washington Closure Hanford, a joint-venture cleanup contractor at the U.S. Energy Dept.’s former weapons-making site in eastern Washington, and a subcontracting team will soon remove five massive steel-reinforced concrete “hot cells.” While no longer in use, they previously allowed site employees to work with nuclear materials without radiation exposure. Removal of the cells, inactive since 1987, and their three-story steel-framed research building enclosure will start this year under a $43-million subcontract.
DOE awarded the work to Northwest Demolition and Environmental, a joint venture led by Northwest Demolition and Dismantling, Tigard, Ore. The team also includes Bluegrass Concrete Cutting, Bigge Crane and Rigging, MACTEC and DCI Engineering.
“This subcontract is for the most difficult, complex and hazardous work we expect to face in regard to demolishing Hanford’s old nuclear facilities,” says Tom Kisenwether, the contractor’s subcontracts manager. The building containing the cells has had radioactivity levels as high as 40,000 curies, say site officials. It includes one underground level.
The cells, which are nearly three stories tall with concrete walls four to six feet thick, have multiple crawl spaces, manipulator ports, ductwork, tanks, pipes and other attached components and systems. Research in the building, which dates from the 1940s, involved analysis of highly radioactive fuel produced at the site’s nuclear reactors. More recently, workers there developed disposal approaches for high-level nuclear waste, such as vitrification, says the contractor.
Hot-cell contamination has been fixed with a sealant. Crews will stabilize them with grout filler, cut them in blocks ranging in size from 20 to nearly 1,000 tons, and bury the waste at an on-site disposal facility. Actual demolition is not set to start until April 2011, and completion is slated for October 2013, say Washington Closure Hanford (WCH) officials.
Northwest Demolition is now doing preliminary engineering and site mobilization. Work includes installing infrastructure, constructing a haul route for the cut-up blocks and installing two large gantry cranes to remove blocks from the building. Several other major demolition projects are to begin in the coming months in the area of the site managed by WCH under a $2.4-billion contract. The contractor is a joint venture of URS Corp., Bechtel and CH2M Hill Cos.