Editing Sellafield (section)

===Start of nuclear activity===
[[File:HD.15.003 (11824034284).jpg|thumb|The site in 1956. In foreground Calder Hall cooling towers and two Magnox reactors. Background L to R: First Generation reprocessing plant, Windscale pile chimneys.]]
{{main|Windscale Piles}}
After the War, the Sellafield site was briefly in the ownership of [[Courtaulds]] for development as a rayon factory, but was re-acquired by the Ministry of Supply for the production of plutonium for [[nuclear weapon]]s.  Construction of the nuclear facilities commenced in September 1947 and the site was renamed Windscale Works. The building of the nuclear plant was a huge construction project, requiring a peak effort of 5,000 workers. The two air-cooled and open-circuit, [[graphite]]-moderated Windscale reactors (the "[[Windscale Piles]]") and the associated First Generation Reprocessing Plant, producing the first British weapons grade [[plutonium-239]], were central to the UK nuclear weapons programme of the 1950s.

Windscale Pile No.1 became operational in October 1950, just over three{{nbsp}}years from the start of construction, and Pile No.2 became operational in June 1951.