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Building History

The Department of Energy's Hanford Site contains 560 square miles, located in three Washington Counties: Benton, Franklin, and Grant. "The B Reactor is housed in the 105-B Reactor Facility in the 100-B/C Area of the Hanford Site. It is located approximately 0.5 miles south of the Columbia River and 3.5 miles east of State Highway 240 at the Vernita Bridge crossing. The 105-B Reactor, designed by the E.I. du Pont Nemours Company under direction of the Manhattan Project, was the first full-scale production reactor ever created. The reactor was one of the three original reactors built at the Hanford Site, formerly the Hanford Engineering Works. Construction of the 105-B Reactor began June 7, 1943, and fifteen months later, on September 26, 1944, the reactor became operational. The B Reactor operated from September 26, 1944, to February 12, 1968." (See US Department of Energy.gov, http://www.hanford.gov/doe/history/files/BReactorMuseumPhase1.pdf, pages B-2, B-3, accessed 11/15/2006) Approximately 14 buildings occupuied the 100-B Area when first built in 09/1944.

Over the years, a number of government contractors operated the Hanford B Reactor: first, E.I. du Pont Nemours and Company (1943-09/1946), next, General Electric Company (09/1946-1964), and Douglas United Corporation (1964-1968). The Hanford B Reactor was commissioned 09/1944 and decommissioned 02/1968.

The American Society of Mechanical Engineers placed the Hanford B Reactor on its list of Historic Mechanical Engineering Landmarks in 1976. Its website said of the reactor: "The Hanford B-Reactor was the first plutonium production reactor to be placed in operation. Its success made possible the subsequent development of atomic energy. The research work, engineering, and planning required to make the reactor operate is one of our most advanced achievements. Much of the reactor core, cooling system, shielding, and auxiliary systems were designed by mechanical engineers. Located near the Columbia River, with a sure electric power source from the Bonneville and Coulee Dams, the Hanford B reactor was a graphite-moderated, water-cooled reactor, designed to operate at 250 million watts. It was loaded in September of 1944 under the personal charge of Enrico Fermi and went critical on September 26 that year. During World War II, Hanford was the site for fuel fabrication plants and chemical separation facilities. B reactor plutonium was used in world's first nuclear explosion at the Trinity Test in Alamogordo, N.M., in 1945, and also in the bomb dropped on Nagasaki, Japan, August 9 of that year, prior to the end of World War II. B Reactor tritium was used in the world's first test detonation of a hydrogen bomb on Bikini Atoll in the South Pacific in 1952." (See American Society of Mechanical Engineers [ASME].org, "#14 Hanford B Reactor," accessed 08/29/2022.)

In 09/1976, the American Society of Mechanical Engineers selected the Hanford B Reactor as a National Historic Mechanical Engineering Landmark. The US Department of the Interior named the Hanford B Reactor a National Historic Landmark on 08/25/2008.

The reactor was shut down for six weeks for the creation of large coolant flow facilities (Project CG-558).