Re: shielding contaminants

[David Walland <David.Walland@bristol.ac.uk>]

By far the major background gamma component on our Gamma Spectrometer here in the Safety Office of the 
University of Bristol is the K-40  1.46 MeV gamma.  We are in an area of quite low U and Th and these may be much 
more important for you.  I anticipate that you would probably find considerable K-40 in concrete.

David Walland
University of Bristol (UK)
David.Walland@bristol.ac.uk


On Fri, 10 Nov 95 08:16:20 -0600 Daniel A. Low, PhD wrote:

> From: Daniel A. Low, PhD <low_da@rophys.wustl.edu>
> Date: Fri, 10 Nov 95 08:16:20 -0600
> Subject: shielding contaminants
> To: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> 
> I have a rather unusual shielding problem to solve.  I have to shield some 
> scintillation detectors from ambient background radiation, and want to do it in 
> the most cost effective manner.  The radiation level has to be reduced by a 
> factor of 1000.  I have determined the thickness required of lead, steel, and 
> concrete (in order of decreasing cost) to provide this level of shielding for a 
> 1 MeV photon (the average background gamma energy I used for the shielding 
> calculations).  However, I am concerned that I will be adding as many background 
> gammas from the shielding material that I am removing if the shielding material 
> has low-level radiation in it.  Does anyone know which of the three alternatives 
> will provide the least background?  What are the level of contaminants in the 
> proposed shielding materials relative to "normal" soil?
> 
> Thank you in advance,
> 
> Daniel Low, Ph.D.
> 
> 
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