Re: Decommissioning criteria

[sbrightwell@shepmill.com (Shane Brightwell)]

Andrew:

I can't immediately put my hands on a basis for the 35 peeks U in soil.
However, I doubt that it is dose-based (or even risk-based).  I was
thinking that the value for Unat + decay products was closer to 10.

Regarding your question about dose conversion factors and their applicability:

1)  There are no dose-based criteria in final-rule form, to my knowledge,
for uranium recovery facilities (NMA staff would be a good reference for
reasons why this is so, what are the prospects w.r.t. cleanup criteria @ UR
facilities, etc.).  10CFR40 App. A is still the rule regarding Ra-226 and
(indirectly) associated isotopes, including, I believe, Th and U.
Generally, UR facility decommissioning plans involve the
proposal/negotiation of some cleanup limit(s) for Th (U) based on factors
such as ingrowth, or maybe risk-based limit(s).

2)  If you are working under the requirements of the new 10 CFR 20 Subpart
E, I think you'll find a concensus that the dose conversion factors in
NUREG 1500 were replaced by those in NUREG 1549.  1549 is a
draft-for-comment for performing dose assessments based on A SPECIFIC
SCENARIO (as was 1500); probably residential in your case.  If you pull the
numbers from 1549, you get a 25 mrem/yr value ranging from about 11.5 -
14.5 pCi/g, depending on the percentile chosen.  1549 incorporates NUREG
5512.  Also, "draft" software is available from NRC called DandD (contact
Christine Daily).  You'll find that there is a strong push in the industry
to hang on to RESRAD, an assessment software package that has been in use
for some time now.

If D&D is upon you, I suggest you become acquainted with two documents:
MARSSIM and DG-4006.  These two will likely be THE guidance for
implementing the new final rule.  MARSSIM is already in final form, DG-4006
is still in draft form.  I can help you get copies of any of the above if
you're in need.

Keep in mind that the D&D industry is currently in a state of flux.  This
means that what is applicable today may be history tomorrow (cite 5849).
What you will likely find in your quest for knowledge is much guidance, and
a good bit of tolerance and understanding by regulatory bodies.


Contact me if you need to talk more about it.


Respectfully, 

Shane Brightwell



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Shane Brightwell
Senior Staff Engineer
Health Physicist
Shepherd Miller, Inc.
3801 Automation Way
Suite 100
Fort Collins, CO 80525
Ph: (970)223-9600 (main)
    (970)206-4315 (office)
FAX:(970)223-7171
mailto:sbrightwell@shepmill.com
http://www.shepmill.com
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