Re: RE: Rule of Thumb for BETA contamination

[LIPTONW@detroitedison.com]

This is a swag.  The energies referred to are probably average energies.  The 
higher the average energy, the greater the % of betas that penetrate the dead 
layer of skin.  Remember, only betas > 70 kev give any dose at all.   
 
The opinions expressed are strictly mine. 
Here's to a risk free world, and other fantasies. 
 
Bill Lipton 
liptonw@detroitedison.com

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• To: Multiple,recipients,of,list,radsafe@romulus.ehs.uiuc.edu
• Subject: RE: Rule of Thumb for BETA contamination
• From: "radsafe@romulus.ehs.uiuc.edu" <radsafe@romulus.ehs.uiuc.edu>
• Date: 02 Oct 97 12:40:29
• Reply-to: radsafe@romulus.ehs.uiuc.edu

On  2 Oct 97 at 10:25, Sorensen, Tony wrote:

> 
> Shapiro (1990) offers the following (table 2.1):
> 
> Dose rate from 100 beta particles per second per cm-2 equals   =
> approximately:
> 
> 56 mrad/hr (C-14); 33 mrad/hr (Ca-45); 11 mrad/hr (P-32); 11 mrad/hr
>   = (Sr-90). Note:  Parallel beam (Jaeger, 1968, p. 14).

In reviewing the above referenced table, I'm now confused.  The above 
decreases wrt energy.  But the absorbed dose rate to skin from 
surface contamination (measured in activity per sq cm) increases wrt 
energy.  I would expect that the beta particle flux (or is it 
fluence?) would be directly proportional to activity per unit area.  
So what changes the function from a negative to positive wrt energy?

Kent N. Lambert, M.S., CHP
lambert@auhs.edu
Allegheny University of the Health Sciences
Hahnemann Division
Radiation Physics and Safety, MS 106
Broad and Vine Streets
Philadelphia, PA  19102-1192

215-762-8768 (voice)
215-762-7683 (fax)  

Disclaimer:  All opinions are well reasoned and insightful.
Needless to say, they are not (necessarily) the opinions of my employer.

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