RE: Cs-137 and Pu-239+240

["Fulmer, Philip" <philip.fulmer@cplc.com>]

Paul,

Based on the limited information in your posting, I would be wary about
using the Cs-137/Pu-239+240 ratio.  As you point out, the key issue is
the differing chemical characteristics of cesium and plutonium, which
are reflected in the k_d values for partioning.  The k_d values are of
course soil-dependent and the plutonium k_d has a relatively strong
dependence on the pH of the soil.  So the soil type is of  UTMOST
importance.  In addition, amount of rainfall since deposition has an
important role in changing the ratio.  

If the intent of the ratio is to identify weapons detonation type
information, I would think the plutonium isotopic ratios would be of
much more use in identifying the source of the plutonium.

Best regards and good luck with this one.

Philip

__________________________
Philip C. Fulmer, PhD, CHP 
Carolina Power & Light Company
Harris Energy and Environmental Center
3932 New Hill-Holleman Road
New Hill, NC 27562
philip.fulmer@cplc.com
(919) 362-3363      

>----------
>From: 	Charp, Paul[SMTP:pac4@cdc.gov]
>Sent: 	Wednesday, September 23, 1998 3:42 PM
>To: 	Multiple recipients of list
>Subject: 	Cs-137 and Pu-239+240
>
>Radsafers:
>
>I am having some interesting conversations (arguments?) over the importance
>or relevance of Cs-137/Pu-239+240 ratios in soils.  At this point in time, I
>am not too comfortable in naming the site or the state.  However, we are
>collecting samples for Pu analyses but Cs was not included in the sampling
>plan.  The state health department believes that the Cs ratio is important
>in determining the source of Pu.  In my reviews of environmental data from
>different locations, there does not appear to be any uniform value for the
>Cs/Pu ratio.  The questions I have are: 1) is there a benefit for
>calculating these ratios, especially since the data for the site in question
>does not yet exist; 2) how important is the soil type given the fact that Cs
>and Pu have different chemical characteristics and; 3) is there an accepted
>Cs/Pu ratio for environmental samples, especially those samples near
>background values?
>
>thanks --  
>
>Paul Charp (pac4@cdc.gov)
>
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