What was the first of these types in which was supervised by Walter Zinn of the Manhattan Project?
Walter Zinn Walter Henry Zinn (December 10, 1906 – February 14, 2000) was a nuclear physicist who was the first director of the Argonne National Laboratory from 1946 to 1956. He worked at the Manhattan Project's Metallurgical Laboratory during World War II, and supervised the 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 designed and built several new reactors, including Experimental Breeder Reactor I, the first nuclear reactor to produce electric power, which went live on December 20, 1951.
British contribution to the Manhattan Project Britain contributed to the Manhattan Project by helping initiate the effort to build the first atomic bombs in the United States during World War II, and helped carry it through to completion in August 1945 by supplying crucial expertise. Following the discovery of nuclear fission in uranium, scientists Rudolf Peierls and Otto Frisch at the University of Birmingham calculated, in March 1940, that the critical mass of a metallic sphere of pure uranium-235 was as little as 1 to , and would explode with the power of thousands of tons of dynamite. The Frisch–Peierls memorandum prompted Britain to create an atomic bomb project, known as Tube Alloys. Mark Oliphant, an Australian physicist working in Britain, was instrumental in making the results of the British MAUD Report known in the United States in 1941 by a visit in person. Initially the British project was larger and more advanced, but after the United States entered the war, the American project soon outstripped and dwarfed its British counterpart. The British government then decided to shelve its own nuclear ambitions, and participate in the American project.