National Historic Landmark- X-10 Reactor, Oak Ridge National Laboratory

When it went into operation on November 4, 1943, this was the world's first full-scale nuclear reactor and the first to produce significant amounts of heat energy and measurable amounts of plutonium; in 1946, it was the first to produce radioactive isotopes for medical therapy.

For many years, X-10 was the principal atomic research facility in the United States.

Credits and Sources:

Information courtesy of the National Park Service.