Y-12 ELECTROMAGNETIC SEPARATION PLANT

(1942 - 1945)
Places > Oak Ridge: Clinton Engineer Works

Electromagnetic separation was a latecomer in the race to find the best method for large-scale production of uranium-235. Ernest Lawrence first considered the possibility in early 1941, but it was fall of 1941 before he aggressively moved forward with research in his laboratory at the University of California, Berkeley. Not until December 1941 did the S-1 Section recommend assigning him $400,000 to assist the effort. Lawrence's success at separating microgram quantities of uranium-235 soon catapulted electromagnetic separation to the forefront. In a March 9, 1942, report, Vannevar Bush told President Franklin D. Roosevelt that the electromagnetic method might provide a short cut to the atomic bomb. At an S-1 meeting on May 23, Lawrence optimistically stated that he foresaw no fundamental difficulties in building a large-scale electromagnetic plant. The jump from laboratory equipment to a full-scale plant was great, he admitted, but by fall he could be producing four grams of uranium-235 per day in his laboratory and, if parallel development could start at once on a hundred-gram-per-day plant, the first product would appear in one year.

Lawrence sought to locate the full-scale plant close to his laboratory in the Shasta Dam area of northern California. At the S-1 meeting with the Army on June 25, Army representatives recommended that all full-scale plants be built at the Oak Ridge, Tennessee, site, but when Lawrence objected the conferees agreed to postpone a decision on location of the electromagnetic plant. After serious study of the Shasta Dam area, Lawrence finally capitulated to the Oak Ridge site in early September. The S-1 Executive Committee meeting at Bohemian Grove on September 13 and 14 agreed to construct a large-scale electromagnetic plant at Oak Ridge that would produce 100 grams per day. Design and procurement were to begin at once. Construction began in February 1943 at a site codenamed Y-12. For details on the Y-12 plant, see the Design, Construction, and Operation entries in the Events section. See also the Electromagnetic Separation entry in the Processes section.

The Y-12 site consisted of 825 acres located in Bear Creek Valley a few miles south of the community of Oak Ridge. Project engineers selected the location partly because the wooded ridges paralleling the valley provided security and would limit the effects of a major explosion or similar accident. Ample room existed between the ridges for numerous plant facilities that, at the height of plant operations, included 9 main process buildings and some 200 auxiliary structures, with nearly 80 acres of floor space. The process buildings contained 9 of the larger, first stage Alpha racetracks and 8 of the second stage Beta racetracks, with 2 racetracks per building. Chemical buildings were constructed to prepare the feed materials for the racetracks and handle the final product from the Beta racetracks. Auxiliary structures included the hospital, laundry, change houses, warehouses, laboratory buildings, shops, cafeterias, and administration buildings. Construction employment, at its peak in July 1944, numbered almost 12,000. Operation employment, at its peak in August 1945, was almost 22,000. Construction costs were $303 million; operation costs through December 1946 were $237 million; and research expenditures almost $20 million. Total costs were almost $573 million.

Electromagnetic separation was the final stage in the uranium enrichment process, with the thermal diffusion and gaseous diffusion processes providing feed material. The uranium-235 in the Hiroshima bomb came from the Beta racetracks. After the war, the gaseous diffusion method for uranium enrichment proved more efficient, and the electromagnetic method was abandoned. By the end of 1946, all nines of the Alphas and six of the Betas were dismantled. Two of the Beta racetracks continued in use producing radioisotopes. Although no longer in operation, the two Betas remain essentially as they were during the war. The Y-12 site continues to serve in a national security capacity for the Department of Energy's National Nuclear Security Administration.

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. For further information, see 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), and Manhattan District History, Book V - Electromagnetic Project, Volumes 1 through 6. Also useful is J.L. Heilbron and Robert Seidel, Lawrence and his Laboratory: a History of the Lawrence Berkeley Laboratory (Berkeley: University of California Press, 1990). The photograph of the Y-12 calutron is courtesy Oak Ridge National Laboratory (via the Lawrence Berkeley National Laboratory). The photograph of the Y-12 racetrack is courtesy the National Archives; it was taken by Ed Westcott.