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1960s "Nth Country Experiment" Foreshadows Today's Concerns Over the Ease of Nuclear Proliferation

July 1, 2003

William Burr, editor

Recent issues of the Bulletin of the Atomic Scientists and the Guardian (UK) (Note 1)   describe a fascinating experiment, sponsored by Lawrence Radiation Laboratory during the mid-1960s, to determine whether a non-nuclear power could develop a nuclear weapons capability more or less from scratch, without access to classified information.  For U.S. government officials this was not an academic exercise; since the mid-to-late 1950s, U.S. policymakers, intelligence analysts, and policy-oriented academics had been thinking and writing about the "Nth country problem"--the possibility that some undetermined number of countries would develop nuclear weapons capabilities.  The problem of nuclear proliferation, as it eventually became known, provoked concern that the addition of new nuclear-armed states would create a more unstable and perilous world.  For example, during a 1963 press conference, President John F. Kennedy suggested that the possibility of a world, during the 1970s, with 15 or 20 nuclear powers, posed the "greatest possible danger and hazard." (Note 2

To better gauge the threat of nuclear proliferation, administrators at Lawrence Radiation Laboratory wanted to determine what it would it would take for a single-minded Nth country to build a bomb.  The lab hired two newly-minted physicists, David Dobson and Robert Selden, with no access to or knowledge of classified information, to "produce a credible nuclear weapons design."  Although Dobson and Selden lacked access to classified information, they knew, just as every would-be nuclear proliferant has known since August 1945, the most important nuclear "secret" of all: that it is possible to design and produce nuclear weapons.  As Manhattan project director General Leslie Groves had testified in 1945, "the big secret   that the thing went off   told more to the world and to the physicists and scientists of the world than any other thing that could be told to them." (Note 3)    The two scientists received "Q" clearances for nuclear weapons design information because any information that they developed on nuclear design would, under the law, be considered secret and "born classified."  After three "man-years", the two physicists had produced a "credible" design for an implosion nuclear weapon that would be triggered by a plutonium pit. According to the articles, which are based on interviews with the participants, the experiment was a success.  The amateur bomb designers learned that they had produced a plan for a device that, if constructed and tested, would have as much explosive force as the weapon that had devastated Hiroshima in August 1945. 

Both the Bulletin and the Guardian articles draw on the "Summary Report of the Nth Country Experiment," edited by Lawrence physicist W. J. Frank in March 1967. The Energy Department partly declassified this report in 1995  in response to a FOIA request by the National Security Archive.  The document is heavily excised; for example, a bibliography of the unclassified publications that the designers read during the experiment is completely withheld. In addition, the Energy Department excised specific conclusions about the practicability of the design.  Plainly, the Department of Energy's reviewers did not want to release information that would increase anyone's confidence that they could design and develop their own nuclear weapons.  While access to fissile materials remains the most significant barrier to the proliferation of nuclear weapons, at a time when Al Qaeda is racing to get the bomb it is difficult to find fault with the judgment that the release of nuclear weapons design information requires the utmost caution.

1. Dan Stober, "No Experience Necessary," The Bulletin of the Atomic Scientists, May-June 2003, at <http://www.thebulletin.org/issues/2003/ma03/ma03stober.html>, and Oliver Burkeman, "How Two Students Built an A-Bomb," Guardian, 24 June 2003, at <http://www.guardian.co.uk/g2/story/0,3604,983646,00.html>.    Unfortunately, the article in The Guardian shows some confusion about the administration of the U.S. nuclear weapons labs by claiming that the Nth Country Experiment was a "U.S. Army" project.   Although the U.S. nuclear labs had significant military missions, after World War II, Los Alamos laboratory and Lawrence Radiation Laboratory, where the Nth Country experiment took place, were projects of the civilian Atomic Energy Commission and managed by civilian scientists.

2. Press Conference, 21 March 1963, Public Papers of the President John F. Kennedy, 1963 (Washington, D.C., Government Printing Office, 1964), p. 280

3.  As quoted in Arvin Quist, Security Classification of Information: Volume I. Introduction, History and Adverse Impacts (Oak Ridge, Tennessee: Martin Marietta Energy Systems, Inc., September 1989), p. 63.

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