Sacks of pitchblende concentrate at Port Radium awaiting shipment to Port Hope, 1939. NWT Archives/©Richard Finnie/N-1979-063: 0081. Using stored stockpiles, Eldorado began supplying tons of uranium ore to British scientists as well as to American physicists investigating nuclear fission at Columbia University in New York in October 1939. Following a sixty-ton order for uranium oxide from the American government in March 1942, Eldorado was able to reopen its mine in Great Bear Lake with Canadian government assistance.