Re: Paducah plutonium

["J. Andrew Tompkins" <jatalbq@mindspring.com>]

Fellow HPs,

Pu in DU and recycled uranium streams was a topic on RADSAFE several
months ago.  The only individual who had data on that go around was
Gene Carbaugh at PNNL whose comments I saved since they actually
contained some information. I had edited the original so any
misinformation contained in the following is likely of my doing and not
the authors.

> Back when
> Hanford was in the Pu production business, we had a lot of recycled
> U,
> and our uranium processing facilities had operating specifications. 
> Our
> slightly enriched uranium (0.8 to 1.25% by weight U-235) experienced
> many
> cycles.  The maximum allowed levels and observed ranges of
> impurities in a few
> lots processed in 1988 were:
>
> Plutonium      10 ppbpU  (parts per billion parts U)  - US
> billion = 1E+9;   
>               
>                 
> observed was 1-2 ppbpU
> Neptunium      not established, observed range was 0.04 to 0.16
> ppmpU
>                 (parts per million parts U) 
> Thorium     750 ppmpU ;       observed 8-10 ppmpU
> Tc-99       not established;  observed 3-4 ppmpU
> Ru-103,106     <20 microcuries per pound U;  observed < 6
> microcuries
> per pound U
> Zr & Nb-95     <10 microcuries per pound U;  observed < 4
> microcuries
> per pound U
>
> We created a reference level of impurity mixture for bioassay monitoring
> data
> interpretation.  (We applied the reference impurity level to uranium
> bioassay
> data to allow for the dose contribution from these impurities, which
> would never
> be seen in a bioassay program.)  The reference impurity level we
> used was:
>
> Plutonium      0.4 nCi Pu-alpha per g-U   (based on 5 ppbpU)
> Neptunium      0.4 nCi Np-237 per g-U     (based on 0.5 ppmpU)
> Thorium     5 pCi Th-232 per g-U       (based on 50 ppmp
> U)
> Tc-99       0.2 microcuries Tc-99 per g-U (based on 10 ppmp U)
> Ru-103,106  40 nCi Ru-106 per g-U (based on 20 microcuries per
>                      pound)
> ZrNb-95     20 nCi Ru-106 per g-U   (based on 10 microcuries
> per
>                       pound)
>
> We considered the reference impurity level mixture to be a worst case
> picture.
> The impurities added slightly to the committed effective dose for the
> mixtures.
> For class D uranium mixtures, it increased the dose by about 16%; for
> class W
> the increase was only 6%; and there was no impact on the class Y mixture
> dose."


Andrew Tompkins
Woodstock, GA  

jatalbq@mindspring.com




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