[ RadSafe ] Low background Shielding Material

[franz.schoenhofer at chello.at]

Both explanations are correct. I can testify for both because of bad experience. In one shielding made from old lead with a commercial steel frame we could clearly see Co-60, in another one we observed elevated concentrations of Cs-137. The latter was made from very old steel - actually a steam locomotive from the beginning of the 20th century. Unfortunately it had for many decades been exposed on a scrapyard in the open air to weather and also nuclear fallout. Rust is an excellent scavenger for radionuclides and especially Cs-137. I experienced this also during my work on Mururoa and Fangataufa: Exposed stainless steel objects showed no contamination, while rusty iron did. 

I have seen shieldings for gamma-spectrometry made of steel from old battleships,  but they had been sunk and thus protected from fallout.

Best regards,

Franz  


------------------------------------------------------------------------------------------

> 
> Von: "Baratta, Edmond J" <edmond.baratta at fda.hhs.gov>
> Datum: 2006/06/08 Do PM 08:34:30 CEST
> An: "'Vernig, Peter G.'" <Peter.Vernig at va.gov>, 
> 	radsafe at radlab.nl
> Betreff: RE: [ RadSafe ] Low background Shielding Material
> 
>  
> I believe that the Cobalt-60 was used in the Furnace linings to measure the
> thickness of them. The iron (steel) making ate away at the walls of the
> furnaces.  They kept track of the thickness this way.  Beta emitters had
> been (maybe still are) to measure the thickness of products such as paper ,
> etc to measure the thickness. Polonium-210 (alpha emitter) is still used to
> counteract 'static' electricity.
> 
> Edmond J. Baratta
> Radiation Safety Officer
> Tel. No. 781-729-5700 x 728
> Fax:  781-729-3593
> edmond.baratta at fda.gov
> 
> These are my opinions and not that of my Agency!!
> 
> -----Original Message-----
> From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf
> Of Vernig, Peter G.
> Sent: Thursday, June 08, 2006 11:09 AM
> To: radsafe at radlab.nl
> Subject: [ RadSafe ] Low background Shielding Material
> 
> Group,
> 
> I have heard many times that "Pre World War II battleship steel" is used
> for extremely low background shielding.  I had always wondered about
> that as it seemed that an infinitesimal amount of fallout would find its
> way into steel.  But then I heard another explanation that made more
> sense something to do with the fabrication process that apparently
> changed post WWII and involved a small amount of Co-60 I think.
> 
> Does anybody out there know what the explanation is?
> 
> Any opinions in this e-mail are solely those of the author, and are not
> represented as those of the VA Eastern Colorado HCS, the Dept. of
> Veterans Affairs, or the US Government.
> 
> Peter G. Vernig, Radiation Safety Officer, MS-115, VA Eastern Colorado
> Health Care System, 1055 Clermont St. Denver, CO 80220,
> peter.vernig at va.gov, Phone= 303.399.8020 x2447; Fax = 303.393.5026,
> alternate fax, 303.393.5248
> 
> "...whatever is true, whatever is noble, whatever is lovely, whatever is
> admirable, if anything is found to be excellent or praiseworthy, let
> your mind dwell on these things."
> 
> Paul of Tarsus
> 
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