Enrico Fermi of Scientific Research and Development, as the Advisory Committee on Uranium was now known, met on 18 December 1941, with the U.S. now engaged in World War II, making its work urgent. Most of the effort sponsored by the Committee had been directed at producing enriched uranium, but Committee member Arthur Compton determined that a feasible alternative was plutonium, which could be mass-produced in nuclear reactors by the end of 1944. He decided to concentrate the plutonium work at the University of Chicago. Fermi reluctantly moved, and his team became part of the new Metallurgical Laboratory there. The possible results
Marshall Holloway as a laboratory instrument to test critical mass calculations and the effect of various tamper materials. The Water Boiler group was headed by Donald W. Kerst from the University of Illinois, and the group designed and built the Water Boiler, which achieved its criticality in May 1944 under the control of Enrico Fermi, after one final addition of uranium enriched to 14% uranium 235. It was world third reactor but the first reactor to use enriched uranium as a fuel, using most of the world's supply at the time, and the first to use liquid nuclear fuel in the form