The World's First Nuclear Reactor Was a Stack of Graphite in a Squash Court
Remembering the Chicago Pile, the First Nuclear Reactor
On December 2, 1942, the coldest day in Chicago in nearly fifty years, a team at the University of Chicago's Stagg Field started up the Pile — forty thousand graphite blocks holding uranium, with hand-operated cadmium rods as the only radiation protection. Neither the university nor the city was told. It went critical, ran for half an hour, and then became the blueprint for the reactors that produced plutonium for Trinity and Nagasaki.
One line that was scratched out of every copy of the report, but is just visible in originals by holding it up to the light at the right angle, argued that, should the United States be the first country to use nuclear weapons in war, it "might cause other nations to regard us as a nascent Germany."