Pile No. 1 went critical in October 1950 , but its performance was about 30 per cent below its designed rating . Pile No. 2 went critical in June 1951 , and was soon operating at 90 per cent of its designed power . The Piles had been designed to produce 90 kg of plutonium annually . The first irradiated fuel rods were sent for processing in January 1952 , and Tom Tuohy retrieved the first sample of British plutonium on 28 March 1952 . Enough Windscale plutonium for an atomic bomb was delivered to the weapons division at Aldermaston in August , and Britain 's first nuclear device was successfully detonated in the Operation Hurricane test in the Monte Bello Islands in Western Australia on 3 October 1952
Operation Hurricane
Operation Hurricane
Windscale Piles