[ RadSafe ] Testing bombs

John Jones john.p.jones at usu.edu
Tue Jul 1 09:29:19 CDT 2008

There is a page on "The Manhattan Project, An Interactive History" website with links to PDF's of several books including one to Robert Serber's "The Los Alamos Primer."

This link should take you to that page.

John P. Jones
Radiation Safety
Utah State Univ.
(435)  797 - 2888
john.p.jones AT usu.edu

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of Steven Dapra
Sent: Monday, June 30, 2008 6:21 PM
To: Dukelow, James S Jr; radsafe at radlab.nl
Subject: RE: [ RadSafe ] Testing bombs

June 30


         Thank you for your explanation of the subtleties of a Pu bomb, and
for recommending Serber's book.  I also appreciated your explanation of the
distinctions between atomic and chemical explosions.

         I will look on Amazon for Serber's book.

Steven Dapra

At 10:52 AM 6/30/08 -0700, Dukelow, James S Jr wrote:

>Nobody has really answered Dapra's original question, which has some
>contemporary relevance.
>The difference between the U-235 bomb and the Pu-239 bomb is that the
>Pu-239 was contaminated with other isotopes of Pu that have significant
>spontaneous fission rates.  If the process of assembling a critical mass
>was "slow" (say, tens of milliseconds), there would be a significant
>probability that the assembling critical mass would be "pre-ignited" by
>stray neutrons from the spontaneous fissions, leading to a lower yield --
>a "fizzle".  The answer was to used carefully designed explosive charges
>to assemble the critical mass very quickly.  Until Trinity, the implosion
>design was theoretical and the test was need to give confidence that the
>weapon would work.
>All of this is very nicely described in The Los Alamos Primer, by Robert
>Serber.  It is the annotated notes of the lectures that Serber gave to
>physicists and other arriving at Los Alamos to participate in the
>Manhattan Project.  The notes were published in 1992 and are currently
>available from Amazon.
>This problem did not exist with U-235 and the physicists were quite
>confident it would work the first time.
>The current relevance is that Iran, and earlier, North Korea is/were using
>both plutonium production and uranium enrichment to pursue nuclear weapon
>capability.  The weaponization issues remain with plutonium weapons and
>uranium weapons remain simple to implement once sufficient fissile
>material is available (although "deliverable" weapons may be more of an issue).
>Dowell's linguistic distinction between nuclear (fission and fusion)
>explosions and atomic/chemical explosions is not standard usage, but is
>reasonable.  The nuclear weapons involve the release of the nuclear
>binding energy of the atomic nucleus, while chemical explosions release
>the chemical binding energy of the electron orbitals.
>Hanford's weapons mission is over and it is probably not to hard to
>arrange tours of most of the facilities, although I haven't tried to do it.
>Best regards.
>Jim Dukelow
>Pacific Northwest National Laboratory
>Richland, WA
>jim.dukelow at pnl.gov
>These comments are mine and have not been reviewed and/or approved by my
>management or by the U.S. Department of Energy.
>-----Original Message-----
>From: radsafe-bounces at radlab.nl on behalf of Steven Dapra
>Sent: Sat 6/28/2008 8:49 AM
>To: radsafe at radlab.nl
>Subject: [ RadSafe ] Testing bombs
>June 28, 2008
>         From time to time I have read that one of the Hiroshima and
> Nagasaki bombs
>had to be tested before it was used, and that one did not --- that the
>engineers were so certain the latter bomb would explode that they didn't
>bother testing it.  I also read recently that hydrogen bombs must be
>tested.  Of these three types of bombs, which ones must be tested, and
>why?  For the one that did not have to be tested, why not?  (I don't have
>any bombs I want to test, I am merely curious.)
>Steven Dapra
>sjd at swcp.com

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