1943 - The federal government chooses Hanford to make plutonium for the Manhattan Project, the secret wartime effort to build an atomic bomb. 1943 - 30,713 employees September 1944 - B Reactor, the world’s first production reactor, is turned on. August 1945 - The “Fat Man,” a bomb made with Hanford plutonium, is dropped on Nagasaki, three days after the bombing of Hiroshima. The Japanese surrender six days later. Dec. 2, 1949 - The U.S. Air Force intentionally releases a large amount of radiation over Eastern Washington as part of an experiment. There are no public warnings. 1950s - The government builds more reactors to increase plutonium production. Some of the reactors dump radioactive water into the Columbia River. 1963 - N Reactor is built to produce both plutonium and electricity. 1971 - The government announces N Reactor will close, but keeps it open after heavy lobbying from the TriCities and the Northwest congressional delegation. 1981 - President Ronald Reagan announces $180 billion arms buildup, triggering a race in the coming decade to produce more plutonium. 1986 - Hanford managers release declassified documents revealing for first time Hanford’s radioactive contamination of eastern Washington in ‘40s and ‘50s. 1988 - N Reactor is shut down and Hanford’s military mission ends. 1989 - Washington state, the Department of Energy and the U.S. Environmental Protection Agency sign an agreement to clean up Hanford’s radioactive mess. 1991 - The Cold War ends with collapse of Soviet Union. 1993 - Energy Secretary Hazel O’Leary pledges a new “openness” for the DOE and vows to reform operations at the nation’s weapons plants, including Hanford. 1994 - Hanford’s cleanup budget reaches $2 billion. 1994 - 18,760 employees