[ RadSafe ] Testing bombs

[Conklin, Al (DOH)]

Hanford does have public tours periodically that are announced to the
public. They fill up very quickly once announced though. 

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of Dukelow, James S Jr
Sent: Monday, June 30, 2008 10:53 AM
To: Steven Dapra; radsafe at radlab.nl
Subject: RE: [ RadSafe ] Testing bombs


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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