RE: What is Weapons Grade - RGPu NOT bomb tested

["Franta, Jaroslav" <frantaj@aecl.ca>]

Bernard L Cohen [mailto:blc+@pitt.edu] wrote on Wednesday August 16, 2000
12:10 PM

<SNIP>
U.S. government bomb designers have been able to use Reactor grade Pu for a
bomb, but it was not easy and the
bomb is not reliable and has low explosive yield. This bomb was ordered 
by the Carter Administration to support its anti-proliferation political
positions -- if a bomb cannot be made from Reactor grade Pu there is no
proliferation problem from LWR power plants.
<SNIP>
<><><><><><><><><><>

Comment :

as regards  "build[ing] a nuclear explosive with Reactor grade Pu (=
"RGPu"), the issue is NOT as clear-cut as might appear, because of confusion
in the definition of RGPu. It turns out that this old test information also
uses the old RGPu definition - which is NOT what we would call RGPu today !

Dr. Jeremy Whitlock gives some details on this in his web posting, "How
easily can an atomic bomb be made with spent CANDU fuel?" at URL
http://www.ncf.carleton.ca/~cz725/cnf.htm#x2

I quote :

The only publicly known US test of a reactor-grade device was a 1962
explosion, partially declassified in 1977. However, in 1962 the term
"reactor-grade" included any purity less than 93% Pu-239 [14]. The plutonium
for the 1962 test came from a British MAGNOX reactor (a dual-purpose
electricity/plutonium-production design), and is suspected of being in the
range 80-90% Pu-239, although this fact remains classified [15,16]. 

[14] DOE Facts, "Additional Information Concerning Underground Nuclear
Weapon Test of Reactor-grade Plutonium", Washington, D.C.,
http://apollo.osti.gov/html/osti/opennet/document/press/pc29.html, June
1994. 

quote from [14] :

Prior to the 1970's, there were only two terms in use to define plutonium
grades: weapon-grade (no more than 7 percent Pu-240) and reactor-grade
(greater than 7 percent Pu-240). In the early 1970's, the term fuel-grade
(approximately 7 percent to 19 percent Pu-240) came into use, which shifted
the reactor-grade definition 19 percent or greater Pu-240. 
-------------

[15] A. DeVolpi, "A Cover-up of Nuclear Test Information?", Physics and
Society, Vol. 25, No. 4, http://physics.wm.edu/~sher/aoct96.html, October
1996. 

quote from [15] :

The 1962 detonation involved plutonium of a quality below that of weapons
grade. To reinforce its 1967 announcements that "high-irradiation level
reactor-grade plutonium can be used to make nuclear weapons," the US
government added in 1977 that "a nuclear test was conducted using reactor
grade plutonium" and "it successfully produced a nuclear yield." As a result
of the Openness Initiative formulated by Secretary O'Leary, DOE announced in
1994 that the plutonium was "provided" by the UK and the upper limit of
explosive yield was 20 kt. [1,2] 
<snip>
In fact, the missing data are likely to be quite discouraging to potential
proliferators, thus fortifying existing perceptions about inherent
difficulties in weaponization of civilian plutonium. 
<snip>
Fresh disclosures from London indicate that the plutonium could not have
been what we now consider to be reactor-grade[3]. DOE now implies, but
doesn't assert, that the plutonium was fuel grade. 
Meanwhile, other nations have publicized their disagreement with the DOE
"spin" on declassified test information. In fact, the French "scorned the US
government affirmation that it successfully exploded a weapon made with
'reactor-grade' plutonium."[4] During the 1950s the British carried out two
tests with sub-grade plutonium that they considered disappointing. Based on
these results, they went on to make weapons only from high- grade materials.
Although the results of the tests were reported in an official UK book, the
information is considered classified in the US. This British data is not
consistent with the 1962 test conclusions reported to the American public.
<snip>
The glaring shortfall in data and information released about the 1962 test
is cause for suspicion about the quality, origin, or success of the
experiment. The unreleased information can hardly be of more proliferant
value than the specific data already divulged for other nuclear-explosive
experiments. In fact, the missing data are likely to be quite discouraging
to potential proliferators, thus fortifying existing perceptions about
inherent difficulties in weaponization of civilian plutonium. 
------------

Jaro
frantaj@aecl.ca
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