Canada was deeply involved with the United States and the United Kingdom in the Manhattan Project during World War II. After the war, however, the United States excluded Canada from direct participation in its nuclear weapons program.
By 1945, Canada decided to build a small reactor and a pilot plant to extract plutonium. On August 13, 1945, senior Canadian nuclear officials revealed publicly Canada’s role in the Manhattan project. In the press release for this event, they wrote of the “design of a pilot plant for the production of atomic bomb materials.”
Because the United States adapted a policy against sharing any of the secrets of plutonium separation, the Canadians with British cooperation had to independently work out much of the chemistry and chemical engineering of plutonium separation.1
Canada’s small reactor reached full power in late 1948. The first “hot run” in the plutonium plant took place in 1949. The plant, however, never operated very well and was shutdown in 1954. While the plutonium separation plant operated, it processed a total of 517 uranium rods and extracted 17 kilograms of plutonium.
Despite its commitment to develop the capability to acquire nuclear explosive materials, Canada did not develop an interest in developing nuclear weapons. A senior Canadian official said in an interview that Canada never had a nuclear weapons program per se, but it was technically well placed to proceed if it had wished to do so. In 1948-49, Canada gave up the nuclear option, deciding not to pursue nuclear weapons on its own or with the United Kingdom.
Until the mid-1960s, Canada provided uranium to the U.S nuclear weapons program. Afterwards, Canada decided not to provide any nuclear material for nuclear weapons programs.
Canada also sold plutonium from its NRU reactor to the U.S. Atomic Energy Commission (AEC) from 1959 to 1964. This plutonium was in the form of spent fuel that was shipped to United States for processing. In total, the AEC recovered about 250 kilograms of weapon-grade plutonium.
1 The information on Canada’s domestic plutonium separation program is from Wilfrid Eggleston, Canada’s Nuclear Story, (Harrap Research Publications, London, 1966), chapter 12.