Re: shielding contaminants

["EMIL KERREMBAEV" <EKERREMBAEV@r06.tdh.state.tx.us>]

Daniel,
You are right the present shielding materials contain a some 
radioisotopes from A-bomb testing, Nuclear Power Plants 
accidents...etc. But my experience tells that it is still match better
to use a shielding, than no shielding at all. First you it will 
sufficiently reduce a background. Second you can always calibrate a 
spectrometer to known shielding background. Also there is a 
possibility to get commercially the shielding with very low background 

(from ships construction materials which drowned before I World War), 
but it is very expensive. Hope this will help.
Good luck.
E.K.
 





> Date sent:      Fri, 10 Nov 95 08:17:36 -0600> Send reply to:  
radsafe@romulus.ehs.uiuc.edu
> From:           "Daniel A. Low, PhD" <low_da@rophys.wustl.edu>
> To:             Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Subject:        shielding contaminants

> 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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