Re: RADSAFE digest 3216

[Dick King <king@reasoning.com>]

 >
 >Date: Wed, 7 Jun 2000 11:24:04 +0100 
 >From: "Bradshaw, Keith" <Keith.Bradshaw@nnc.co.uk>
 >To: "'radsafe@romulus.ehs.uiuc.edu'" <radsafe@romulus.ehs.uiuc.edu>
 >Subject: was 1/2 kilo of Pun - now 65 ton
 >Message-ID: <DD1E19A9AFC2D311A32200508B5589EF072001@nnc.co.uk>
 >
 >Dear Radsafers
 >
 >It was on the UK BBC News the other day that the US and Russia have signed
 >an accord to *destroy* 65 ton of weapons grade plutonium.  Is it the case
 >that this will take place in the accelerator facilities that we've discussed
 >here previously?  This amont of Pu represents a huge energy resource, and I
 >just hope it is going to be destroyed in such a way that the energy is used
 >usefully.  What's going to happen to all the fission products?
 >
 >Personal views only
 >
 >keith.bradshaw@nnc.co.uk
 >
 >END
 >
 >

The accelerator would convert the Pu into isotopes that would be unsuitable for
a weapon [too much spontaneous fission] without making it unusable for power
production.  That's also what happens to most recycled Pu from power reactors;
one neutron converts U238 into a weapons-grade Pu239, but the second sometimes
fissions it but sometimes converts it into Pu240, which is a contaminant making
it unsuitable for weapons.  To make weapons-grade Plutonium you need to
circulate the U238 through the reactor after only a short time; very
inefficient for power production because the reactor has to be turned off often
[unless you have a live refueling design] but you don't get Pu240 .

If i remember correctly, yet a third neutron makes Pu241, which is prized by
NASA for its really high rate of spontaneous fission [to power deep space
probes, with a half life of only a couple of decades].  Or maybe it's the 240
that's used by NASA.

-dk
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