Re[2]: Occupational Exposure Limits for Radon Exposure

[Steven.Rima@DOEGJPO.COM (Steven Rima)]

     The current 10 CFR 835 definition of "background" means radiation 
     from..."radon and its progeny in concentrations or levels existing in 
     buildings or the environment which have not been elevated as a result 
     of current or prior activities." The definition of occupational 
     exposure specifically excludes background radiation and so excludes 
     most radon exposure. From my experience at a number of DOE sites, the 
     majority ignore all radon as background, so no occupational radon 
     monitoring/dose reporting is done.
     
     We do environmental remediation of uranium mines/millsites and other 
     sites where radium was concentrated and/or used, so radon is certainly 
     elevated by "prior activities." The major problem with occupational 
     monitoring for radon is how to account for REAL background radon 
     exposure. For example, at a millsite with elevated radium in the 
     tailings on top of the ground, how much radon is from the ground under 
     the tailings, and therefore true background, and how much radon is 
     from the tailings? There really is no easy answer to this question 
     since radon concentrations vary due to many factors.
     
     We have an exemption to 10 CFR 835 that redefines ALL radon on our 
     sites as occupational, (ALL radon is occupational inside the fence and 
     ALL radon is background outside the fence!) and also increased the 
     monitoring threshold from 100 mrem/y to 500 mrem/y (CEDE).
     
     Also in my experience, most sites do NOT record or report personnel 
     contaminations when radon and its progeny are determined to be the 
     culprit because radon is "background."
     
     BTW, we do extensive personnel occupational monitoring for radon and 
     end up assigning some fairly large annual doses to some workers based 
     on this monitoring.
     
     Steven D. Rima, CHP, CSP
     Manager, Health Physics and Industrial Hygiene
     MACTEC-ERS, LLC
     steven.rima@doegjpo.com
     
     


______________________________ Reply Separator _________________________________
Subject: RE: Occupational Exposure Limits for Radon Exposure
Author:  "Fleming; Kenneth" <knflemin@bechtel.com> at Internet
Date:    11/11/98 2:36 PM


I'm currently away from my reference material, but the old 10CFR835 required 
that exposures to radon and/or daughters above a dose equivalent of 100 
mrem/year had to be accounted and documented.  We requested and received an 
exemption (really an extension) of the 100 mrem/year exposure to radon/radon 
daughters to 500 mrem/year through the DOE.  We went through the process of 
assessing exposure over a long term with an active radon daughter measuring 
device (Canadian make, AlphaNuclear).  This data allowed us to document that 
occupational sampling would not be necessary.
     
Check with Riasp Madora at Fernald.  They were set up to conduct long term 
(~1 month) air sampling for radon daughters, but I'm not sure whether they 
have ever had to sample occupationally.
     
Kenny Fleming
knflemin@bechtel.com
(423) 220-2306
     
     <snip>
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