Crane pulls out radioactive hot cells at Hanford
Apr 29, 2010
A hot cell once used to work with some of Hanford's most radioactive materials was slowly moved Wednesday out of the building that had been its home since 1953.
It's the fifth of nine contaminated hot cells being removed from the Hanford 327 Building, a research facility less than two miles north of Richland. During the Cold War, the hot cells were used for testing on highly radioactive materials, particularly fuel elements and cladding irradiated at Hanford reactors as part of plutonium production for the nation's nuclear weapons program.
Numerous accidents had spread contamination within the building, including areas outside the hot cells where remotely operated tools were used to work with the fuel.
"This is the culmination of years of work inside the building to remove and stabilize contamination," said Gary Snow, deputy director of deactivation and demolition, as a gantry crane slowly crawled along tracks Wednesday to move the fifth hot cell.
It's among the progress Department of Energy contractor Washington Closure Hanford is making as it tackles some of the most difficult demolition work on Hanford buildings along the Columbia River.
In the nearby 324 Building, multi-story hot cells that were built into the structure are being cleaned out and filled with concrete. They then will be cut into blocks weighing from 20 tons to almost 1,000 tons each for removal and disposal.
Washington Closure is using a different approach at the 327 Building, which has modular hot cells.
After contamination was either removed or stabilized with a coating of fixative throughout the 30,000-square-foot building, subcontractor Barnhart Crane and Rigging of Portland started removing the hot cells.
A 20-foot-high and 30-foot-wide opening was cut into the side of the metal building so a Barnhart gantry crane that runs on rails could be installed deep into the building. After diamond wire saws are used to cut bolts that secured the hot cells to the floor, the crane lifts the cells one at a time and carries them out of the building.
Each is lowered onto a metal plate that becomes the base of a waste container box that will be built around the hot cell. When all the hot cells are in boxes, the boxes will be filled with grout, or concrete.
The largest of the cells is about 15-by-8-by-10-feet. It's made of high-density steel and lead and weighs 342,000 pounds. Its shipping weight will be about 456,000 pounds, and the gantry crane will lift it and other boxed hot cells so a truck can drive underneath.
They will be taken to Hanford's landfill for low-level radioactive waste, the Environmental Restoration Disposal Facility in central Hanford. A gantry crane also will be used there to maneuver the boxes.
Washington Closure expects to have the hot cells shipped next month, allowing demolition of the building using an excavator equipped with shears. The building should be down by September's end.
"This is one of the most hazardous buildings along the Columbia River, so this will be a real milestone for us to get it down and away from the river," Snow said.
Read more: http://www.thenewstribune.com/2010/04/29/1167374/crane-pulls-out-radioactive-hot.html#ixzz0mW33MImt
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