Use of Canadian Uranium in the World's First Atomic Bombs
The Eldorado Mine was closed in 1940 due to World War II and an over-supply of radium.
The mine was re-opened in 1942 by Eldorado Mining and Refining Ltd., a federal crown company, to supply uranium for the Manhattan Project.
Processing of the radium and uranium ore resulted in the establishment of a world class refining facility at Port Hope, Ontario.
Exhaustion of the uranium ore led to mine closure in 1960.
Despite all the rush, and the selection of only the best stopes for mining, production ... tended to fall. Its best month, August 1943, yielded only 80,000 pounds of U3O8 embodied in concentrates. By December, the worst month, yield was down to 18,454 pounds.... The Americans were not pleased by this development, which Eldorado's management did its best to conceal. 'It will be noted,' a U.S. Army geologist reported in early 1944, 'that the mine is behind in production some 27 tons of U3O8 as of April 1944 and that it has continued to fall behind continuously since 1 December [1943]. Unless this rate of production is considerably increased ... it seems unlikely that the contract commitments can be met.'
It will be recalled that there were two major sources of uranium available to the would-be bomb-makers on the allied side -- the Belgian Congo and Great Bear Lake. Both Great Bear Lake and the Union Minière pit at Shinkolobwe were shut down in 1940, and the Shinkolobwe mine in fact remained closed until 1944.
The Katangese ores were different from those produced at Eldorado's Great Bear Lake mine. If the Belgian ore had priority, then Eldorado's own ore would have to wait until the Belgian order was finished, since the two required quite different methods of treatment.
Just how important was Canada?
Not as important as some believed, Mackenzie replied. The Manhattan Project was 'not entirely dependent on Canadian ore' and a bomb might have been managed entirely 'without our material.' Nevertheless, uranium was scarce, and Canada's uranium had probably gained in importance because of the scarcity.