Operation Totem status, the British government restarted its own development effort, which was given the cover name "High Explosive Research". The first British atomic bomb was tested in Operation Hurricane at the Montebello Islands in Western Australia on 3 October 1952. The main purpose of the trial was to determine the acceptable limit on the amount of plutonium-240 which could be present in a bomb. The plutonium used in the original Hurricane device was produced in the nuclear reactor at Windscale, but the Windscale Piles did not have anything like the capacity to provide sufficient material for the British government's planned weapons
History of the Teller–Ulam design "secret"), the United States agreed to exchange some of its nuclear designs with Great Britain, leading to the 1958 US-UK Mutual Defence Agreement. The People's Republic of China detonated its first device using a Teller–Ulam design June 1967 ("Test No. 6"), a mere 32 months after detonating its first fission weapon (the shortest fission-to-fusion development yet known), with a yield of 3.3 Mt. Little is known about the Chinese thermonuclear program, however. Very little is known about the French development of the Teller–Ulam design beyond the fact that they detonated a 2.6 Mt device in the "Canopus" test in August