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The S-1 Executive Committee
met to consider the Lewis Report on December 9, 1942, just weeks after
Allied troops landed in North Africa. Most of the morning
session was spent evaluating the controversial recommendations that
only a small electromagnetic plant be built. Lewis and his
colleagues based their recommendations on the belief that Lawrence
could not produce enough uranium 235 to be of military
significance. But since the calutron could provide enriched
samples quickly, the committee supported the construction of a
"small" electromagnetic plant.
Conant disagreed with the
Lewis committee's assessment, believing that uranium had more weapon
potential than plutonium. And since he knew the that gaseous
diffusion could not provide any enriched uranium until the gaseous
diffusion plant was in full operation, he supported the one method
that might, if all went well, produce enough uranium 235 to build a
bomb in 1944.
During the afternoon, the
S-1 Executive Committee went over a draft Groves had prepared for Bush
to send to the President. It supported the Lewis committee's
report except that it recommended skipping the pilot plant stage for
the pile. After Conant and the Lewis committee met on December
10 and reached a compromise on the electromagnetic method, Groves'
draft was amended and forwarded to Bush.
On December 28, 1942,
President Roosevelt approved the establishment of what ultimately
became a government investment in excess of $2 billion, $.5 billion of
which was itemized in Bush's report submitted on December 16.
The Manhattan Project was authorized to build full-scale gaseous
diffusion (K25 at Oak Ridge) and plutonium plants (X-10 Reactor at Oak
Ridge) and the compromise electromagnetic plant (Y-12 at Oak Ridge),
as well as heavy water production facilities. In his report,
Bush reaffirmed his belief that bombs possibly could be produced
during the first half of 1945 but cautioned that an earlier delivery
was unlikely.
No schedule could guarantee
that the United States would overtake Germany in the race for the
bomb, but by the beginning of 1943 the Manhattan Project had the
complete support of President Roosevelt and the military leadership,
the services of some of the nation's most distinguished scientists,
and a sense of urgency driven by fear. Much had been achieved
between Pearl harbor and the end of 1942.
No single decision created
the American atomic bomb project. Roosevelt's December 28
decision was inevitable in light of numerous earlier ones that, in
incremental fashion, committed the United States to pursuing atomic
weapons.
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