U Canyon—a huge, windowless concrete monolith that housed secret Cold War-era plutonium and uranium processing work at the U.S. Energy Dept.'s Hanford site, the former nuclear-weapons production facility in eastern Washington—has sat empty and inert for more than four decades. Now, however, the cavernous structure will become a beehive of activity as a technology test site, featuring a first-time DOE process in which 20,000 cu yd of specially formulated, cement-like grout is pumped beneath the edifice to stabilize its radioactivity before final demolition.
The facility's name derives from its proportions: 810 ft long, 66 ft wide and 77 ft tall. Built in 1944, it was used at first to train workers extracting plutonium from irradiated fuel rods, but the plant also housed uranium reprocessing in the 1950s. U Canyon is one of five processing plants at Hanford and one of the largest in DOE's U.S. nuclear complex. Federal stimulus funds expedited the $5-million grout project, but full demolition is not budgeted until 2015, says DOE. The project is part of an agreement reached in 2005 between state and federal agencies. DOE says the pact originally targeted 2024 for demolition.