Re: FW: Thorium Lenses (fwd)

[michael_coogen@hq2ccgw.hq.dla.mil]

I have had pass discussion with the NRC on items containing thorium.  Thorium is
uaually a component of a chemical compound (thorium fluoride) used to coat and 
protect items containing optics and/or incorporated into glass to increase 
strength.  The coating on these optics are usually uniform in composition 
whether contain in a coat or incorporated into the item totally.  The exemption 
apply to the coat and to the item if incorporated.  The 30 perecent by weight is
the total weight of the applicable item containing thorium..mike coogen sends

______________________________ Reply Separator _________________________________
Subject: FW: Thorium Lenses (fwd)
Author:  radsafe@romulus.ehs.uiuc.edu at hq2ccgw
Date:    9/1/95 7:15 AM


Here is the Fwd thorium glass message:
     
----- cut & Fwd'd -----------
     
From: Lindsey, Gary
To: RadSafe
Subject: Thorium Lenses
Date: Thursday, August 31, 1995 2:50PM
     
Third and final try:
     
>From 10 CRF 40.13, throrium contained in finished optical lenses is 
considered an unimportant quantity provided each lens does not contain more 
than 30 percent by weight of throium.
     
To meet this exemption:
  1.  Does the throium have to be uniformly distributed through the lens? 
  2.  Does this exemption apply to thorium coating on lenses?
     
Specific references would be appreciated.
     
****************************************************************************  
*******************************
Gary Lindsey
Radiation Safety Branch, Office of Environmental Management 
88 ABW/EMB
5490 Pearson Road
Wright-Patterson AFB, Ohio  45433-5332 
Email:  lindseg@wrigem.wpafb.af.mil
Telephone:  (513) 257-2010    FAX:  (513) 476-1534 
****************************************************************************  
*******************************
Standard disclaimer applies.