[ RadSafe ] Radioactivity in Granite Countertops

[franz.schoenhofer at chello.at]

Stewart.

The most appropriate person on Radsafe to ask would be without doubt Dan McCarn. 

In Vienna - but not only there - streets are covered with what I think is in English "cobble stones" made of granite from northern Lower Austria. When driving on Viennese roads one can easily distinguish between those granite pavements and the asphalt ones. The advantage of the granite cobble stones is without doubt, that they will resist everydays wear for hundreds or thousands of years.....

Best regards,

Franz


---- Stewart Farber <SAFarber at optonline.net> schrieb:
> Does anyone know if there some types of granite that contain NO enhanced
> levels of natural radioactivity? This has never been my experience, but I'm
> no geologist.
> 
>  
> 
> I've done studies with high-pressure ionization chambers in many places
> showing clearly elevated levels of radioactivity contained in granite in
> construction throughout the Northeastern US as indicated by elevated gamma
> dose rates of 20 micro-R/hr [200 nSv/hr] or more  [ in close proximity to
> granite walls -approx. 1 foot distant] vs. typical background dose rates  of
> about 8 micro-R/hr [ 80 nSv/hr] for the area. 
> 
>  
> 
> Every HPIC measurement near granite I've made around Boston [ at the
> Christian Science Church, South Station, Bunker Hill Monument, steps of the
> MA Statehouse, granite Colonial era wharf buildings]  or all around
> Westerly, RI [a town where almost every building is made of granite], or in
> NH or Maine, or  the Harrisburg, PA Capitol granite steps,  has shown about
> a doubling of background dose rate measured with a HPIC a  foot  or so from
> the granite used in construction. 
> 
>  
> 
> Another interesting measurement was of a doubling of background dose rate
> near a large piece of Aswan red granite from Egypt which was used to make a
> sarcophagus for a princess many thousands of  years ago. This ancient
> granite ceremonial Egyptian coffin is currently displayed in front of the
> Boston, MA Museum of Science.
> 
>  
> 
> All  granite mentioned  above would show greatly elevated count rates when
> measured on contact with a standard pancake GM like an Ludlum 44-9 or
> HP-360.  
> 
>  
> 
> However, a friend has recently installed granite countertops which shows
> background rad levels on contact. So has my friend purchased "real" granite
> with all the  natural radioactivity it "should" contain or has she been
> cheated of her little bit of residual elevated U-238, Th-232, and K-40
> radioactivity from the Big Bang?
> 
>  
> 
> Thoughts?
> 
>  
> 
>  
> 
> Stewart Farber
> 
>  
> 
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--
Franz Schoenhofer, PhD, MinRat
Habicherg. 31/7
A-1160 Vienna
Austria
mobile: ++43 699 1706 1227