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Hanford Site (plutonium production)
1943–1987; B Reactor started September 1944· Arms maker, factory or program· Arms makers & war industry
Well documentedSolid records, physical evidence or scientific consensus.
A vast plutonium-production complex on the Columbia River in Washington state, built for the Manhattan Project.
See it on the Battles & Wars map →What happened
In 1943 the Army took about 580 square miles of desert, emptying the towns of Hanford and White Bluffs and removing the Wanapum people from their river lands. DuPont built and ran it; about 50,000 construction workers lived in a temporary camp. B Reactor, the world's first full-scale production reactor, cooled by river water, started in September 1944. Chemical plants then separated plutonium from the irradiated uranium. Nine reactors eventually ran there, the last until 1987.
Why it matters
Its plutonium fueled the Trinity test, the Nagasaki bomb and most of the US Cold War arsenal, and it left America's largest nuclear cleanup.
How we know
Declassified Energy Department records, released in large batches from 1986; B Reactor itself, now toured as part of Manhattan Project National Historical Park; and cleanup reports.
Still debated
Health effects of deliberate releases such as the 1949 'Green Run' on 'downwinders' remain disputed, and cleanup of its tank waste is expected to take decades more.
Connections (3)
▸DuPont's Brandywine gunpowder mills grew into the company that built and ran Hanford Site (plutonium production)Well documented
The connection
The company born at the Brandywine gunpowder mills had become a chemical giant by 1942. At General Groves's request, DuPont designed, built and ran Hanford's reactors and plutonium plants, scaling Fermi's experimental reactor up enormously. Stung by 'merchants of death' charges after World War I, it took a fee of just $1.
When and how
DuPont's Wilmington, Delaware, headquarters and Hanford, Washington, 1942–1946; DuPont engineer Crawford Greenewalt with Manhattan Project scientists; General Electric took over in 1946.
How we know
Manhattan District contracts showing the $1 fee, DuPont company records at the Hagley Museum, and declassified Hanford histories.
Debates and open questions
Credit between DuPont's engineers and the physicists is still weighed; extra fuel tubes DuPont insisted on rescued B Reactor from 'xenon poisoning' in 1944.
▸Hanford Site (plutonium production) made the plutonium dropped on Nagasaki in the Atomic bombings of Hiroshima and NagasakiWell documented
The connection
Hanford's reactors turned uranium into plutonium, which chemical plants extracted and shipped to Los Alamos from early 1945. That plutonium filled the core of the Trinity test device on July 16 and of the Fat Man bomb dropped on Nagasaki on August 9, 1945.
When and how
Hanford, Washington, to Los Alamos, New Mexico, February–July 1945; DuPont operators and Army couriers.
How we know
Declassified Manhattan District production and shipping records.
Debates and open questions
Whether a second bomb was needed only three days after Hiroshima, before Japan's leaders had fully responded, is among the most debated questions of the war.
▸Hanford Site (plutonium production) made plutonium for the Cold War arsenal of Nuclear weapons and deterrenceWell documented
The connection
After 1945 Hanford grew to nine reactors and became the main US plutonium factory of the Cold War, making about two-thirds of the roughly 100 metric tons the US produced. That plutonium went into tens of thousands of warheads, the arsenal behind nuclear deterrence.
When and how
Hanford, Washington, 1945–1987, run by General Electric and later contractors for the Atomic Energy Commission and the Energy Department.
How we know
The Energy Department's 1996 report 'Plutonium: The First 50 Years,' which credits Hanford with about 67 of 103 metric tons.
Debates and open questions
Cleanup of the waste left behind is expected to take decades more and cost hundreds of billions of dollars; estimates keep rising.