- Smyth, Henry D.
Atomic Energy for Military Purposes.
Stanford, CA, Stanford University Press, [1945] 1990.
ISBN 978-0-8047-1722-9.
-
This document was released to the general public by the United
States War Department on August 12th, 1945, just days after
nuclear weapons had been dropped on Japan (Hiroshima on
August 6th and Nagasaki on August 9th). The author, Prof.
Henry D. Smyth of Princeton University, had worked on the
Manhattan Project since early 1941, was involved in a
variety of theoretical and practical aspects of the
effort, and possessed security clearances which gave him
access to all of the laboratories and production facilities
involved in the project. In May, 1944, Smyth, who had
suggested such a publication, was given the go ahead by
the Manhattan Project's Military Policy Committee to
prepare an unclassified summary of the bomb project. This
would have a dual purpose: to disclose to citizens and
taxpayers what had been done on their behalf, and to
provide scientists and engineers involved in the project a
guide to what they could discuss openly in the postwar
period: if it was in the “Smyth Report” (as
it came to be called), it was public information, otherwise
mum's the word.
The report is a both an introduction to the physics
underlying nuclear fission and its use in both steady-state
reactors and explosives, production of fissile material
(both
separation
of reactive Uranium-235 from the much more
abundant Uranium-238 and
production
of Plutonium-239 in
nuclear reactors), and the administrative history and
structure of the project. Viewed as a historical document,
the report is as interesting in what it left out as what
was disclosed. Essentially none of the key details discovered
and developed by the Manhattan Project which might be of use
to aspiring bomb makers appear here. The key pieces
of information which were not known to interested physicists
in 1940 before the curtain of secrecy descended upon anything
related to nuclear fission were inherently disclosed by the
very fact that a fission bomb had been built, detonated, and
produced a very large explosive yield.
- It was possible to achieve a fast fission reaction
with substantial explosive yield.
- It was possible to prepare a sufficient quantity of
fissile material (uranium or plutonium) to build
a bomb.
- The critical mass required by a bomb was within the
range which could be produced by a country with the
industrial resources of the United States and small
enough that it could be delivered by an aircraft.
None of these were known at the outset of the Manhattan
Project (which is why it was such a gamble to undertake
it), but after the first bombs were used, they were apparent
to anybody who was interested, most definitely including the
Soviet Union (who, unbeknownst to Smyth and the political and
military leaders of the Manhattan Project, already had the
blueprints for the Trinity bomb and extensive information on
all aspects of the project from their spies.)
Things never disclosed in the Smyth Report include the
critical masses of uranium and plutonium, the problem of
contamination of reactor-produced plutonium with the
Plutonium-240 isotope and the consequent impossibility
of using a gun-type design with plutonium,
the technique of implosion and the technologies
required to achieve it such as explosive lenses and
pulsed power detonators (indeed, the word
“implosion” appears nowhere in the document),
and the chemical processes used to separate plutonium
from uranium and fission products irradiated in a
production reactor. In many places, it is explicitly
said that military security prevents discussion of
aspects of the project, but in others nasty surprises
which tremendously complicated the effort are simply
not mentioned—left for others wishing to follow
in its path to discover for themselves.
Reading the first part of the report, you get the sense
that it had not yet been decided whether to disclose
the existence or scale of the Los Alamos operation. Only
toward the end of the work is Los Alamos named and the
facilities and tasks undertaken there described. The
bulk of the report was clearly written before the
Trinity test of the plutonium bomb on July 16, 1945.
It is described in an appendix which reproduces
verbatim the War Department press release describing
the test, which was only issued after the bombs were
used on Japan.
This document is of historical interest only. If you're
interested in the history of the Manhattan Project and the
design of the first fission bombs, more recent works
such as Richard Rhodes'
The Making of the Atomic Bomb
are much better sources. For those aware of the scope and
details of the wartime bomb project, the Smyth report is an
interesting look at what those responsible for it felt
comfortable disclosing and what they wished to continue to keep
secret. The forward by General Leslie R. Groves reminds
readers that “Persons disclosing or securing
additional information by any means whatsoever without
authorization are subject to severe penalties under the
Espionage Act.”
I read a Kindle edition from another
publisher which is much less expensive than the Stanford
paperback but contains a substantial number of typographical
errors probably introduced by scanning a paper source
document with inadequate subsequent copy editing.
November 2019 