Hanford B Reactor

B Reactor sits on the Hanford Site in Benton County. The Department of Energy calls it the world's first full-scale plutonium production reactor. DuPont built it for the Manhattan Project from experimental work by Enrico Fermi in Chicago and tests at Oak Ridge.

Construction began in October 1943. Fuel was loaded on September 13, 1944. The reactor went critical at 10:48 p.m. on September 26, 1944 — eleven months after work started. The first plutonium left Hanford for Los Alamos in February 1945 and was used in the Trinity test and, later, the bomb dropped on Nagasaki.

The reactor was shut down in 1946, restarted in 1948, and closed for good in February 1968. It is a National Historic Landmark and part of Manhattan Project National Historical Park. This postcard records the public DOE and Hanford Site history, not a judgment of the war.