the name for the air-cooled, graphite-moderated reactor that was the first British weapons grade plutonium-239 production facility. In 1957, a fire at one of the twin Windscale reactors caused a serious nuclear accident, releasing an estimated 20,000 curies of radioactive material. Milk and other produce from the surrounding farming areas had to be destroyed, and news of the accident was suppressed for fear of alarming the public.