What once was one of the most secure complexes in the nation has been torn down.
The plutonium vault complex, where plutonium for the nation's nuclear weapons program once was stored at Hanford's Plutonium Finishing Plant, has been demolished, the Department of Energy announced Tuesday.
Built in 1971, the vault complex held the top-secret stores of plutonium in metal canisters until they were shipped off Hanford for fabrication for use in weapons.
At Hanford, uranium fuel was irradiated at one of nine production reactors, the plutonium was separated from the fuel at huge processing buildings and then the Plutonium Finishing Plant would turn the plutonium liquids into metal buttons the size of hockey pucks. The plant produced about two-thirds of the nation's plutonium during the Cold War.
At the end of the Cold War, 2,300 canisters of plutonium, each the size of a large coffee can, were left stored at the vault complex under heavy guard as the Plutonium Finishing Plant was cleaned up. The weights of the cans varied, but some held almost 10 pounds of plutonium.
The vaults originally used free-standing pedestals to store the plutonium. But as the plant was stabilized and cleaned out after plutonium production ended at Hanford, storage capacity was increased by laying the canisters on their sides like wine bottles in what employees called "wine racks."
DOE contractor CH2M Hill Plateau Remediation Co. finished emptying the vault of plutonium in 2009, which eased the tight security restrictions at the Plutonium Finishing Plant. The nation's weapons grade plutonium has been consolidated at DOE's Savannah River, S.C., nuclear site.
In 1983, just six years before plutonium processing stopped, an annex was added to the vault complex. It had nine shielded glove boxes which were used to assay and package plutonium. Workers would reach into the box to do work with radioactive materials using gloves attached to portals on the boxes.
CH2M Hill removed the last of the glove boxes from the vault complex in early 2011, after detaching them from furnaces used to heat the plutonium.
Shipping the plutonium off site, removing the glove boxes and other work cleared the way for demolition of the complex to begin late in 2011. The vault complex included six structures covering about 20,000 square feet, and work started to tear down the smaller facilities first.
Debris is being hauled to the Environmental Restoration Disposal Facility, a lined landfill for low-level radioactive waste in central Hanford.
The Department of Energy's Richland Operations Office now is focused on getting environmental cleanup finished along the Columbia River and completing cleanup of the Plutonium Finishing Plant, said DOE spokesman Cameron Hardy.
That includes continued work to remove glove boxes, and other radiological and industrial hazards from the rest of the Plutonium Finishing Plant to prepare it for demolition. The legally binding Tri-Party Agreement requires the plant to be demolished by 2016.