Nuclear reactor lower than had previously been thought. The memorandum was a product of the MAUD Committee, which was working on the UK atomic bomb project, known as Tube Alloys, later to be subsumed within the Manhattan Project. Eventually, the first artificial nuclear reactor, Chicago Pile-1, was constructed at the University of Chicago, by a team led by Italian physicist Enrico Fermi, in late 1942. By this time, the program had been pressured for a year by U.S. entry into the war. The Chicago Pile achieved criticality on 2 December 1942 at 3:25 PM. The reactor support structure was made of wood,
S1W reactor S1W reactor The S1W reactor was the first prototype naval reactor used by the United States Navy to prove that the technology could be used for electricity generation and propulsion on submarines. The S1W designation stands for The land-based nuclear reactor was built at the National Reactor Testing Station, later called Idaho National Engineering Laboratory near Arco, Idaho. The plant was the prototype for the USS "Nautilus" (SSN-571), the world's first nuclear-powered submarine. The specific location within the vast Idaho National Laboratory where the S1W prototype was located was the Naval Reactors Facility. Under the leadership of Admiral Hyman G.