Re: I-125

[David W Lee <lee_david_w@lanl.gov>]

At 07:30 PM 28-01-97 -0600, you wrote:
>     On 1/28/97 Larry R. Sanders wrote, in part:
>      
>     >Can anyone tell me where the 300 dpm limit for releasing of I-125 
>     >contaminated material came from, or the basis for this limit? It 
>     seems I-125 and I-129 require the same release limit as Ra-226, 
>     >Ra-228, Th-230, Th-228, Pa231, and Ac-227. Other isotopes from Iodine 
>     >have a significantly higher release limit.  
>          
>     
>     Larry, you've opened up an old can of worms with this one.  Every 
>     release limit table I've ever seen, from USNRC, USDOE, or agreement 
>     state, has the same limit for I-125.  Yet no one seems to know why.
>     
>     Carl Bergsagel
>     Fred Hutchinson Cancer Research Center
>     cbergsag@fhcrc.org
>     
>     
>     
> I second Carl's remarks and credit Larry for asking about the technical
basis of the release limit for I-125.  I also would sincerely appreciate any
Radsafer trying to answer this question.  Within the DOE, Table 2-2 of the
DOE Radiological Control Manual (RCM), in terms of removable/total/fixed
contamination release limits lumps transuranics and the nuclides specified
by Larry above under the SAME release limit.  Also, I-126,  I-131, I-133
have the same release limit as natural Th, Th-232, Sr-90, Ra-223/224, U-232.
Even though I am supposed to be an HP who ought to be capable of explaining
such things, I have never been able to intuitively understand why the
release limits for radioiodines (which decay via beta/EC and which typically
are more volatile) have the same release limit as transuranics (alpha
emitters).  What radiological and hazard characteristics do the radioiodines
have in common with transuranics and other alpha emitters that logically
merits assigning to them all the same release limit?  In the case of the
DOE, the many problems that DOE HQ has had with the DOE RCM stem largely
from that fact that DOE HQ never developed a 'technical basis' -type
document for the RCM, itself, prior to publishing the RCM as holy writ.
Thus DOE, itself, cannot even explain technically why it specified the
release limits that it did.  Please help.  Thanks

As usual, just my opinion.  REGARDS  David

    
>         
>      
>
>
David W. Lee
Radiation Protection Policy
& Programs Analysis Group (ESH-12)
Los Alamos National Laboratory
PO Box 1663, MS K483
Los Alamos, NM  87545
Ph:  (505) 667-8085
FAX: (505) 667-9726