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J.R. Oppenheimer and General Groves
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Time Periods

1890s-1939:
Atomic Discoveries

1939-1942:
Early
Government Support

1942:
Difficult
Choices

1942-1944:
The Uranium
Path to
the Bomb

1942-1944:
The Plutonium
Path to
the Bomb

1942-1945:
Bringing It All Together

1945:
Dawn of the
Atomic Era

1945-present:
Postscript --
The Nuclear Age


Alpha Racetrack, Y-12 Electromagnetic Plant, Oak RidgeTHE URANIUM PATH TO THE BOMB
(1942-1944)
Events > The Uranium Path to the Bomb, 1942-1944

The uranium path to the atomic bomb ran through Oak Ridge, Tennessee.  Only if the new plants built at Oak Ridge produced enough enriched uranium-235 would a uranium bomb be possible.  General Groves placed two methods into production: 1) electromagnetic, based on the principle that charged particles of the lighter isotope would be deflected more when passing through a magnetic field; and 2) gaseous diffusion, based on the principle that molecules of the lighter isotope, uranium-235, would pass more readily through a porous barrier.  Full-scale electromagnetic and gaseous diffusion production plants were built at Oak Ridge at sites designated as "Y-12" and "K-25", respectively.

K-25 Gaseous Diffusion Plant, Oak RidgeBoth the Y-12 and K-25 plants converted new and untried laboratory technologies directly to large-scale production processes.  At Y-12, the design continuously changed even as construction was ongoing.  Once built, the Y-12 Alpha and Beta "racetracks" went into full operation only slowly, as numerous unanticipated design and equipment problems were encountered.  Originally expected to provide most of the uranium-235 requirements, the K-25 gaseous diffusion plant, due to difficulties in fabricating a suitable barrier, was cut back to a feeder process for Y-12 in the summer of 1943.  The eventually-successful operations at both Y-12 and K-25, however, remained very much in doubt well into 1944. For this reason, the Army, with assistance from the Navy, also implemented the liquid thermal diffusion method of uranium enrichment, in which the lighter isotope concentrated near a heat source within a tall column, at the S-50 plant on the K-25 site as a supplement and a backup.  In the end, it took the combined efforts of all three of these facilities to produce enough enriched uranium for the one and only uranium atomic bomb produced during the war.  

The Clinch River curves around S-50 and the power plant for K-25, Oak Ridge.To learn more about any of these events associated with the uranium path to the bomb, choose a web page from the menu below.  To continue with a quick overview of the Manhattan Project, jump ahead to the description of the "Plutonium Path to the Bomb, 1942-1944."

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Sources and notes for this page.

The text for this page is original to the Department of Energy's Office of History and Heritage Resources.  Portions were adapted or taken directly from the History Office publications: Terrence R. Fehner and F. G. Gosling, Origins of the Nevada Test Site (DOE/MA-0518; Washington: History Division, Department of Energy, December 2000), 26, and Richard G. Hewlett and Oscar E. Anderson, Jr., The New World, 1939-1946: Volume I, A History of the United States Atomic Energy Commission (Washington: U.S. Atomic Energy Commission, 1972), 167.  Click here for more information on the picture of the Alpha racetrack at Y-12.  The photograph of K-25 is courtesy the Federation of American Scientists. The aerial photograph showing S-50, the power plant for K-25, and the Clinch River, is reproduced in the History Office publication: Richard G. Hewlett and Oscar E. Anderson, Jr., The New World, 1939-1946, between pages 296 and 297.

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