Re[4]: Patient Release - A Related Question

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

     So, let's see, using the NRC's numbers, if I live near a nuclear power 
     plant for its nominal 30 year life, I can legally receive up to 100 
     mrem/y x 30 y = 3000 mrem. However, for cleanup, I can receive no more 
     than 25 mrem/y x 70 y = 1750 mrem. Still doesn't add up to me...
     
     BTW, for those of you concerned with the amount of money being spent 
     on cleanup for little or no gain, there is a fascinating analysis of 
     the UMTRA mill tailings cleanup program in the May Health Physics 
     Journal (Vol. 76, No. 5) entitled "Calculation of the Number of Cancer 
     Deaths Prevented by the Uranium Mill Tailings Remedial Action 
     Project." It analyzes 20 different project sites, and comes to the 
     conclusion that in only two was the cost/death prevented less than $1 
     million. Eight had a ratio exceeding $1 billion, with the highest 
     cost/death prevented being $18 Billion! Not a great use of public 
     resources.
     
     Steven D. Rima, CHP, CSP
     Manager, Health Physics and Industrial Hygiene
     MACTEC-ERS, LLC
     steven.rima@doegjpo.com


______________________________ Reply Separator _________________________________
Subject: Re: Re[2]: Patient Release - A Related Question
Author:  Stephen Mcguire <SAM2@nrc.gov> at Internet
Date:    11/2/99 10:48 AM


The justifications for the different limits for environmental cleanups and 
patient release are a little subtle, but they come from the fact that 
environmental pollutants may deliver a dose year after year, whereas a dose from
a patient that approaches the limit is likely to be a once in a lifetime event.

The 15 or 25 mrem/yr for environmental cleanup is driven in large part by the 
EPA's judgement that the maximum acceptable lifetime risk from an environmental 
pollutant is on the order of 10-6 to 10-4/lifetime.  If we assume the annual 
dose is delivered for 70 years those annual rates correspond to lifetime doses 
of 1050 or 1750 mrem.  These correspond to several times 10-4 risk, but the EPA 
considers 15 mrem/yr to be close enough to 10-4 to be acceptable, but 25 mrem/yr
to be not considered by EPA to be close enough to be  acceptable.  NRC, on the 
other hand, considers the risk from 25 mrem/yr to be close enough to be 
acceptable.
     
However, the 10-4 criterion for acceptable lifetime risk applies only to 
environmental pollutants, not necessarily to patient release.  The acceptable 
risk in that case is governed by the dose limits.  Normally the maximum 
acceptable annual dose to a member of the public is 100 mrem.  However, in 
certain cases 500 mrem can be accepted if there is justification and if the dose
is not likely to occur repeatedly to the same individual.  The 500 mrem value 
was adopted for patient release because there was considered to be justification
and a single individual would seldom receive a dose approaching that limit more 
than once in a lifetime.
     
Thus, the basis for the limits is not exactly the same, but the results in terms
of lifetime risk are not that different either.
     
<snip>
     
Stephen A. McGuire
Mail Stop T-4D18
Incident Response Operations
U. S. Nuclear Regulatory Commission
Washington, DC 20555
301-415-6204
sam2@nrc.gov 
     
     
     
     
     
     
     
     
     
     
     
     
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