Measures for Progress: A History of the National Bureau of Standards

382 WORLD WAR II RESEARCH (1941-45)
Partly in order to accelerate the contract research on uranium proj-
ects initiated by NDRC and provide better coordinated direction, OSRD
was established in June 1941, with direct access to the President. Urgently
required was information on the critical mass of a bomb, design data on
a gaseous diffusion plant for large-scale separation of uranium isotopes, and
assessment of a heavy-water pile. Apart from the NDRC assignments of the
Advisory Committee (now OSRD's S—i Section), at the direction of OSRD
the problem of large-scale uranium isotope separation was turned over to
groups under Lawrence and Urey, and that of production of element 94
(plutonium) to Compton's group at the new and cryptically named "Metal-
lurgical Laboratory" at the University of Chicago.54
By the end of 1941 research groups at Columbia, Princeton, Chicago,
California and elsewhere had achieved considerable basic knowledge of
nuclear properties and of the physical constants of the materials involved.
Sufficient mathematical calculations had been made to suggest the prob-
ability that the critical size of a bomb either with concentrated U235 or the new
element plutonium was almost certainly within practical limits.55 On the
other hand, Fermi had constructed an experimental graphite and uranium
pile at Columbia but no chain reaction had been achieved principally because
of the poisoning effect of the boron in the uranium. No appreciable amount
of U235 had been separated from only traces of plutonium had been
produced, and the production of large quantites of uranium metal, heavy
water, and pure graphite still remained largely in the discussion stage.56
One week before Pearl Harbor, Dr. Briggs's S—i Section made the
decision recommending a major all-out effort to construct the bomb. Eleven
days after Pearl Harbor, at another meeting in Dr. Briggs's office at the
Bureau, Arthur H. Compton, as head of a committee of the National Academy
of Sciences, outlined the time schedule that the project must strive to meet:
By July 1, 1942, to determine whether a chain reaction was
possible.
By January 1943, to achieve the first chain reaction.
Smyth Report, p. 71; Hewlett and Anderson, p. 45.
66 If plutonium was still an unknown quantity in November 1941, it was known with some
certainty that a spectacularly destructive fission bomb would result from bringing quickly
together a sufficient mass of between 2 and 100 kg. (4.4 and 220
pounds) —although nothing like even 2 kg of the material was yet in sight (Hewlett and
Anderson, p. 47). On this basis it was conjectured that from 1 to 10 tons of would be
required to construct the bombs necessary to devastate the major military and industrial
objectives in Germany. Tonnage production, either by the gaseous diffusion or centrifuge
method, was believed to be 3 or 4 years away (Baxter, pp. 427—428).
°°Smyth Report, p. 73.