On December 2, 1942, Enrico Fermi, Leo Szilard and the Canadian nuclear physicist Walter Zinn used Canadian uranium to produce the first self-sustaining nuclear chain reaction at Columbia University. Photo courtesy Wikimedia Commons. Zinn supervised the construction of the Chicago Pile-1, the world’s first nuclear reactor.
Canadian scientists who worked in the Manhattan Project also included Jordan Carson Mark and Louis Slotin at Los Alamos, and Clarence Johnson at Oak Ridge. Walter Zinn helped to create the first nuclear chain reaction at the University of Chicago in December 1942 and became head of the Argonne National Laboratory in 1946. Slotin assembled the core of the first plutonium atom bomb exploded in the Trinity test in New Mexico on July 16, 1945. His body was returned to Winnipeg in a lead-lined coffin after he suffered massive radiation exposure in a nuclear accident the following year. Mark helped to develop the hydrogen bomb in the early 1950s.