Enrico Fermi is considered to have invented nuclear power, along with his colleagues at the University of Chicago in 1942, by successfully demonstrating the first controlled self-sustaining nuclear chain reaction. His experiment using uranium isotopes showed that the neutrons released by splitting an atom could go on to split other atoms and released other neutrons. Fermi's group built the first nuclear reactor based on their discovery.
The 1940s saw a great amount of advancement in knowledge and use of nuclear power. Three years after Fermi's experiments, the United States dropped atomic bombs on Hiroshima and Nagasaki to force a Japanese surrender and end World War II. In 1946, the Oak Ridge Laboratory in Tennessee created the first nuclear power produced radioisotopes for use by civilians. Plans to commercialize nuclear power for electricity began in 1948.