Graphite-moderated reactor electricity generation: There have been a number of research or test reactors built that use graphite as the moderator. The first artificial nuclear reactor, Chicago Pile-1, a graphite-moderated device that produced between 0.5 watts and 200 watts , was constructed by a team led by Enrico Fermi in 1942. The construction and testing of this reactor (an "atomic pile") was part of the Manhattan Project. This work led to the construction of the X-10 Graphite Reactor at Oak Ridge National Laboratory, which was the first nuclear reactor designed and built for continuous operation, and began operation in 1943. There have
Experimental Breeder Reactor I Arco, Idaho in 1955, the first time a city had been powered solely by nuclear power. Besides generating the world's first electricity from atomic energy, EBR-I was also the world's first breeder reactor and the first to use plutonium fuel to generate electricity (see also the Clementine nuclear reactor). EBR-1's initial purpose was to prove Enrico Fermi's fuel breeding principle, a principle that showed a nuclear reactor producing more fuel atoms than consumed. Along with generating electricity, EBR-1 would also prove this principle. EBR-I was deactivated by Argonne in 1964 and replaced with a new reactor, Experimental Breeder Reactor II.