The Windscale reactor accident—50 years on

The policy of the government of the United Kingdom to independently manufacture nuclear weapons in Great Britain was formulated in the mid-1940s and implemented in the late-1940s and early-1950s; full details are to be found in the monumental treatise on the subject by Margaret Gowing and Lorna Arnold [1]. A significant component of this implementation was the construction of a plutonium production factory on the remote coast of the then county of Cumberland (now part of Cumbria) in north-west England. The site chosen was that of the former ordnance factory at Sellafield, which, with its sister factory just down the road at Drigg, had produced TNT during the Second World War. Construction began in September 1947, and the site was renamed Windscale to avoid confusion with Springfields Works, the uranium processing and fuel manufacturing establishment near Preston. Plutonium was initially created in the uranium fuel of two nuclear reactors (the Windscale Piles), chemically separated from untransmuted uranium and the waste by-products of nuclear reactions in a reprocessing plant, and then converted to metallic form before being sent to the Atomic Weapons Research Establishment at Aldermaston, near Reading, for machining and assembly as a weapon. The speed with which the policy was put into practice is truly remarkable: Windscale Pile No. 1 was operational in October 1950 followed by Pile No. 2 in June 1951, the first reprocessing run took place in 1952 and the extracted plutonium provided the explosive material in the UK’s first nuclear weapons test (in Australia) on 3 October 1952, just five years after building work commenced at Windscale. This speed, however, was achieved at a premium, as we shall see.