Important dates in the history of nuclear power By 2011 Dec 2, 1942 Enrio Fermi makes the first nuclear reactor,the Chicago Pile 1 . Dec 20, 1951 An experimental reactor makes enough energy to light 4 lightbulbs Apr 17, 1956 The first commerical nuclear power plant is built. Jul 16, 1973 American utilities buy 41 nuclear power plants. Dec 19, 1993 The number of nuclear power plants in the U.S is 109.