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Re: Sandblasting Grit



At 02:43 PM 24/5/96 -0500, you wrote:
>
>I am looking for information related to concentrations of naturally 
>occurring radionuclides (specifically Th and U) found in sandblasting grit. 
> I have been unable to find reference in NCRP reports.

It depends on the abrasive blast media!! Here in Qld, Australia, the problem
of "warm" abrasive blast media was identified in the eighties sometime. A
specific piece of state legislation (an Order in Council) was passed to deal
with it as all the  abrasive blast media had a specific activity of less
than 74kBq per kg and thus was not defined by our state legislation as a
radioactive substance and was therefore not subject to control by our
Radioactive Substances Act. The Order in Council stipulated that the maximum
specific activity permitted in an abrasive blast media was 1500Bq per kg
(U-238 plus daughters) and 2000Bq per kg (Th-232 plus daughters) - or the
other way around, my memory fails me.

Anyway, as a result, many abrasive blast products were banned from use or
sale here. The warmest ones were (from memory once again so don't quote me)
garnet or ilmenite products contaminated with monozite, and more recently a
zinc slag. Copper slags were typically lower in activity - ie below the
limits referenced above.

Mike (U of Q), you may be more up to date on this, can you offer any advice??

Regards
 
  Alex Zapantis                                         
  Radiation Safety Officer                                     
  Queensland University of Technology 
  Acting Manager       
  Health & Safety Section                             
  Locked Bag No.2                    Ph     : 61 7 3864 3566
  Red Hill Qld 4059                    fax     : 61 7 3864 3993
  AUSTRALIA                           Email  : a.zapantis@qut.edu.au    

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