Re: Decommissioning criteria

["Phil V. Egidi" <7pe@ornl.gov>]

Andrew, The numbers you mention come from old (1980s) NRC guidance.

Check the "Guidelines for Decontamination of Facilities and Equipment Prior to
Release for Unrestricted Use or Termination of Licenses for Byproduct, Source,
and Special Nuclear Material," Policy and Guidance Directive FC83-23, November
4, 1983.

Also look at "Disposal or Onsite Storage of Thorium and Uranium Wastes from
Past Operations," Branch Technical Position, October 23, 1981, 46FR52061.

If I remember right, the 35 pCi/g is for DU, Enriched uranium is soil is 30
PCi/g, U-nat is 10 pCi/g (with decay products).

I don't believe the 35 pci/g is associated with 25 mrem/yr.

If you are in an NRC-regulated program, then you are probably conducting
license termination according to the new 10CFR20 amendments, and would use 25
mrem/yr TEDE from all pathways combined (don't forget ALARA) as a limit.
Depending on your scenarios and other input parameters, you may have a cleanup
value much higher than 35 pCi/g.   NRC has a model described in NUREG/CR-5512,
but I think it has been updated and there is now a software program called
DandD that NRC is using.  DOE recommends RESRAD for its dose-based limits.  EPA
wants different models that are risk-based using the HEAST slope factors for
CERCLA-type cleanups.

NRC is also considering seperate criteria from the dose-based promulgated by
10CFR20 amendments for uranium recovery facilities.  If your facility falls
into this catagory, look at the Federal Register on 7/21/97 p 39093 for
"Radiological Criteria for License Termination: Uranium Recovery Facilities"
Request for additional comment.  NRC is considering using radium-based dose
cleanup limits for uranium at these facilities so that one is not cleaning up
mill tailings to one dose limit and yellowcake to another (have I lost you
yet?).

NUREG-1549, "Guidance on Using Decision Methods for Dose Assessment to Comply
With Radiological Criteria for License Termination." (1998) looks like a good
document for you to look at.  It can be downloaded from
(http://techconf.llnl.gov/radcri/1549.pdf).

Finally, there is MARSSIM and the NRC working paper for comment: Regulatory
Guide for Demonstrating Compliance with the Radiological Criteria for
Decommissionoing, Section C.2: Regulatory Position: Final STatus Survey."  This
is a draft for comment guide on implementing MARSSIM to 10CFR20 license
termination. (http://techconf.llnl.gov/radcri/mod-c2.html)

Hope this sheds some light for you,
Phil Egidi
ORNL/GJ
7pe@ornl.gov



Andrew Scott wrote:

>      Radsafers,
>
>      Can anyone give me a reference for 35pCi/g U in soil for release for
>      unrestricted use, and if this limit is associated with 25mrem/y?  I
>      know this number is out there, but just can't seem to pin down a
>      reference.  Also, do you know if this will be superseded by the
>      numbers in the draft NUREG-1500 (19.3 pCi/g associated with 15mrem/y)?
>
>      Thanks,
>
>      1LT Andrew L. Scott
>      US Army Center for Health Promotion and Preventive Medicine
>      Aberdeen Proving Ground
>      (410)671-5145
>      andrew_scott@chppm-ccmail.apgea.army.mil