Technicians enter a secure room at Hanford operations of a plutonium recycling test reactor, 1961...

Atomic Energy Commission's Hanford operations at Richland, Washington development of a plutonium recycling test reactor operated by General Electric that produced most of the plutonium in the US after 1944. The B Reactor at the Hanford Site was the first large-scale nuclear reactor ever built and a key part of the Manhattan Project during World War II to convert uranium metal into plutonium-239 by neutron activation for use in nuclear weapons. The reactors ceased operation in 1966 and has been designated a U.S. National Historic Landmark since 2008. Photo by Ted Spiegel