Re[2]: Plutonium - Short Essay

[eh_carbaugh@ccmail.pnl.gov]

     At Hanford we use the following isotopic composition (weight %) for 
     weapons-grade plutonium as a default for our internal dosimetry 
     programs.  Actual compositions can vary by a bit - particularly with 
     regard to Pu-238, Pu-241, and Am-241 as the material ages.  The 
     percentages for Pu-239 and -240 remain relatively constant.
     
     Pu-238     0.05 w%
     Pu-239     93.0 w%
     Pu-240      6.1 w%
     Pu-241      0.8 w%
     Pu-242      0.05 w%
     Am-241      0.0 w%
     
     These weight percentages are for "fresh" weapons-grade Pu, which we 
     define (again for internal dosimetry purposes) to be two-weeks post 
     chemical separation and purification.  "Aged" is defined somewhat 
     arbitrarily to mean five years or more of Am-241 ingrowth.
     
     Historically, here at Hanford, weapons-grade Pu was also called 6% Pu, 
     based on the nominal 6% Pu-240 content.  I've seen mixtures ranging 
     from 5-7% Pu-240 which are still referred to as weapons-grade.  By the 
     time we hit 10-12% Pu-240, it is no longer considered weapons-grade 
     (at least here at Hanford).  Maybe the Los Alamos or Livermore folks 
     can shed some unclassified light on this.
     
                Gene Carbaugh
                Pacific Northwest Lab
                eh_carbaugh@pnl.gov
     


______________________________ Reply Separator _________________________________
Subject: Re: Plutonium - Short Essay
Author:  avest@magnus.acs.ohio-state.edu at -SMTPlink
Date:    10/20/95 7:53 AM


>     Plutonium
>
>     Short Essay by Gary Masters
...          In this (weapons) grade of
>            plutonium the desired isotope is Pu-239. Several other isotopes 
>            are present however. In addition to the Pu-239 are Pu-238,
>            Pu-240, Pu-241, Pu-242 and Am-241 (americium). The Am-241 is 
>            the result of the beta minus decay of Pu-241.
     
Would someone please tell me, or direct me to a reference, what "exactly" 
(or on average) are the relative proportions of the above-mentioned Pu 
isotopes in "fresh" weapons-grade Pu of a given "isotope" (per DOE 
reportage) percentage?  For example, suppose a sample of fresh material was 
93% "isotope" (undetermined mixture of Pu-239 and Pu-241), the remaining 7% 
being Pu-240, and decay of Pu-241 may (or may not) have since had time to 
significantly change those percentages, depending on how much of the 
"isotope" was Pu-241.
     
Would those proportions be much different under different manufacturing 
conditions of WGPu, or is every batch identical?
     
I know it's a picky point, having little to do with actual safety, but I 
like to be as accurate as I can.
Albert Lee Vest           The Ohio State University 
Health Physicist    Room 103 1314 Kinnear Road Bldg 
(614)292-1284                     1314 Kinnear Road 
avest@magnus.acs.ohio-state.edu   Columbus OH 43212 
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