Work has begun to remove the chimney of the first pile at Windscale – a landmark in Britain's nuclear history and the site of its worst accident.
On Friday, Sellafield Ltd. announced the chimney had been opened for the first time in 17 years as crews pulled up the 52-metric-ton steel access gantry. This is the first step toward removing the gallery that once held filters that helped keep enormous volumes of radioactive material from entering the atmosphere. The schedule calls for the gallery to be disassembled by the end of 2014, followed by the chimney diffuser in 2018. A tower crane built alongside the chimney will then bring down the remaining structure in sections, according to a Sellafield release. Nuclear Management Partners, a consortium of URS, Amec and Areva, has been in charge of decommissioning activities at Sellafield that include the Windscale project since 2008.
The Windscale piles produced plutonium and tritium for Britain's nascent nuclear weapons program. They were graphite-moderated and air-cooled, using canisters of uranium fuel and other materials pushed through channels in the reactor core, retrieved at the other end and later processed to extract plutonium and other isotopes. In 1957, a buildup of Wigner energy and other factors caused the fuel in the first reactor to ignite and burn for two days. The chimney filters had been added mid-construction at the insistence of physicist John Cockcroft to mitigate a potential accident. Nonetheless, the fire was rated a level-five incident on the seven-level International Nuclear Event Scale, releasing cesium-137 and iodine-131 into the atmosphere.