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MORE URANIUM RESEARCH (1942)
Events
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Difficult Choices, 1942
During the first half of 1942, several routes to a bomb
via uranium continued to be explored. At
Columbia University, Harold Urey worked
on the gaseous diffusion and
centrifuge systems for
isotope separation in the codenamed SAM
(Substitute or Special Alloy Metals) Laboratory. At
Berkeley, Ernest Lawrence continued his
investigations on
electromagnetic separation using the
"calutron" he had converted from his thirty-seven-inch
cyclotron. Phillip Abelson, who had moved
from the Carnegie Institution and the National Bureau of
Standards to the Naval Research Laboratory, continued his
work on liquid thermal diffusion but with
few positive results, and he had lost all contact with the
S-1 Section of the Office of Scientific
Research and Development. Meanwhile Eger
Murphree's group hurriedly studied ways to move from
laboratory experiments to production facilities.
Research on uranium required uranium ore, and obtaining
sufficient supplies was the responsibility of Murphree and
his group. Fortunately, enough ore was on hand to
meet the projected need of 150 tons through
mid-1944. Twelve hundred tons of high-grade ore were
stored on Staten Island, and Murphree made arrangements to
obtain additional supplies from Canada and the Colorado
Plateau, the only American source. Uranium in the
form of hexafluoride was also needed as feed material for
the centrifuge and the gaseous and thermal diffusion
processes. Abelson was producing small quantities, and
Murphree made arrangements with
E. I. du Pont de Nemours and Company and
the Harshaw Chemical Company of Cleveland to produce
hexafluoride on a scale sufficient to keep the vital
isotope separation research going.
Lawrence was so successful in producing enriched samples
of uranium-235 electromagnetically with his converted
cyclotron that Vannevar Bush sent a
special progress report to
President Roosevelt on March 9,
1942. Bush told the President that Lawrence's work
might lead to a short cut to the bomb, especially in light
of new calculations indicating that the
critical mass required might well be
smaller than previously predicted. Bush also
emphasized that the efficiency of the weapon would
probably be greater than earlier estimated and expressed
more confidence that it could be detonated
successfully. Bush thought that if matters were
expedited a bomb was possible in 1944. Two days
later the President responded: "I think the whole thing
should be pushed not only in regard to development, but
also with due regard to time. This is very much of
the essence."
In contrast, the centrifuge and gaseous diffusion work at
Columbia was confronting serious engineering
difficulties. The production of adequate centrifuges
was proving to be a very difficult task, and it looked
like it might take tens of thousands of centrifuges to
produce enough uranium-235 to be of value. Building
an effective, corrosion-proof barrier for gaseous
diffusion systems was even more problematic. Both
separation methods demanded the design and construction of
new technologies and required that parts, many of them
never before produced, be finished to tolerances not
previously imposed on American industry.
Despite the difficulties encountered with the centrifuge
and gaseous diffusion methods, and even with Lawrence's
successes at Berkeley, no clear-cut victor had yet
emerged. The question of which method of uranium
enrichment would prove most effective remained wide open.
Next
Sources and notes for this page.
The text for this page was adapted from, and portions
were taken directly from the
Office of History and Heritage Resources
publications:
F. G. Gosling,
The Manhattan Project: Making the Atomic Bomb
(DOE/MA-0001; Washington: History Division, Department
of Energy, January 1999), 10-11, 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),
168-69. President Franklin Roosevelt's
reply to Vannevar Bush is cited in
Hewlett and Anderson, Jr.,
The New World, 1939-1946, 406. The photograph
of the blocks of uranium is courtesy
Los Alamos National Laboratory; it is reprinted in Rachel Fermi and Esther Samra,
Picturing the Bomb: Photographs from the Secret World
of the Manhattan Project (New York: Harry N. Abrams, Inc., Publishers, 1995),
99. The map of Manhattan Project facilities in
North America is reproduced from Vincent C. Jones,
Manhattan: The Army and the Atomic Bomb, United
States Army in World War II (Washington: Center of
Military History, United States Army, 1988), 463.
The photograph of Ernest Lawrence (and
others) in front of a cyclotron is
courtesy the
Lawrence Berkeley National Laboratory. The photograph of
Columbia University is courtesy the
Library of Congress; it
originated from the Detroit Publishing Company, and it
was a 1949 gift to the Library of Congress from the
State Historical Society of Colorado.
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