Walter Zinn

Walter Zinn was an American nuclear physicist, born in Canada, who became the first director of the Argonne National Laboratory, serving from 1946 to 1956. During the Second World War he worked at the Manhattan Project's Metallurgical Laboratory and supervised construction of Chicago Pile-1, the world's first nuclear reactor, which went critical on December 2, 1942 at the University of Chicago. At Argonne he went on to design and build several new reactors, including Experimental Breeder Reactor I, the first nuclear reactor ever to generate electricity to power a building, which began operating on December 20, 1951.