Nuclear Power

The first nuclear reactor was built during World War II as part of the Manhattan Project to build an atomic bomb. This reactor was constructed under the direction of Italian physicist Enrico Fermi (1901–1954) in a large room beneath the squash courts at the University of Chicago. Until the day on December 2, 1942, when the Chicago reactor was first put into operation, scientists had relied entirely on mathematical calculations to determine the effectiveness of nuclear fission as an energy source; thus, the scientists who constructed the first reactor were taking an extraordinary chance.

That reactor consisted of alternating layers of uranium and uranium oxide with graphite (carbon) as a moderator. Cadmium control rods were used to control the concentration of neutrons in the reactor. Since the various parts of the reactor were constructed by piling materials on top of each other, the unit was at first known as an "atomic pile."