[ExI] EP and Peak oil.

BillK pharos at gmail.com
Fri Apr 4 14:42:07 UTC 2008

On Fri, Apr 4, 2008 at 2:59 PM, Keith Henson wrote:
>  Why does it scare you?  Unless you take the trouble to make plutonium
>  without Pu 240 in it, the stuff isn't suitable for bombs.  (The 240
>  makes it detonate prematurely, with much less yield.)  The problem is
>  you can make pure Pu 239 if you set up to do so.

No. You mean 'the stuff isn't *ideal* for bombs'.

It still makes a pretty big nuclear explosion and terrorists aren't


Higher concentrations of Pu-240 can result in pre-detonation of the
weapon, significantly reducing yield and reliability. For the
production of weapons-grade plutonium with lower Pu-240
concentrations, the fuel rods in a reactor have to be changed
frequently, about every four months or less.

Some nuclear weapons are typically designed so that a pulse of
neutrons will start the nuclear chain reaction at the optimum moment
for maximum yield; background neutrons from plutonium-240 can set off
the reaction prematurely, and with reactor-grade plutonium the
probability of such "pre-initiation" is large. Pre-initiation can
substantially reduce the explosive yield, since the weapon may blow
itself apart and thereby cut short the chain reaction that releases
the energy.

Nevertheless, even if pre-initiation occurs at the worst possible
moment (when the material first becomes compressed enough to sustain a
chain reaction) the explosive yield of even a relatively simple
first-generation nuclear device would be of the order of one or a few
kilotons. While this yield is referred to as the "fizzle yield," a
one-kiloton bomb would still have a radius of destruction roughly
one-third that of the Hiroshima weapon, making it a potentially
fearsome explosive. Regardless of how high the concentration of
troublesome isotopes is, the yield would not be less.

A successful test was conducted in 1962, which used reactor-grade
plutonium in the nuclear explosive in place of weapon-grade plutonium.
The yield was less than 20 kilotons. This test was conducted to obtain
nuclear design information concerning the feasibility of using
reactor-grade plutonium as the nuclear explosive material. The test
confirmed that reactor-grade plutonium could be used to make a nuclear
explosive. This fact was declassified in July 1977. The release of
additional information was deemed important to enhance public
awareness of nuclear proliferation issues associated with
reactor-grade plutonium that can be separated during reprocessing of
spent commercial reactor fuel. The United States maintains an
extensive nuclear test data base and predictive capabilities. This
information, combined with the results of this low yield test, reveals
that weapons can be constructed with reactor-grade plutonium. 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


Ref:  <http://www.globalsecurity.org/wmd/intro/pu-isotope.htm>


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