[Federal Register Volume 65, Number 114 (Tuesday, June 13, 2000)]
[Notices]
[Page 37186]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-14839]


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NUCLEAR REGULATORY COMMISSION


Use of Screening Values to Demonstrate Compliance With the Final 
Rule on Radiological Criteria for License Termination

    Purpose: This notice provides supplemental information to clarify 
the criteria for using screening values to demonstrate compliance with 
the Nuclear Regulatory Commission's (NRC) Final Rule on Radiological 
Criteria for License Termination (License Termination Rule (LTR)) which 
was issued on July 21, 1997, (62 FR 39058).
    Background: Acceptable license termination screening values of 
common radionuclides for building surface contamination were published 
in the Federal Register on November 18, 1998 (63 FR 64132). Screening 
values of common radionuclides for surface soil contamination were 
published in the Federal Register on December 7, 1999 (64 FR 68395). As 
discussed in these notices, NRC's DandD computer code provides a method 
for calculating screening values for radionuclides in soil, and 
screening values for contamination on building surfaces. NRC used the 
DandD methodology to derive the building surface contamination 
screening values in Table 1 of the November 18, 1998, notice and the 
surface soil contamination screening values in Table 3 of the December 
7, 1999, notice. These screening values correspond to levels of 
radionuclide contamination that would be deemed in compliance with the 
unrestricted use dose limit in 10 CFR 20.1402 (i.e., 0.25 milliSievert/
year, (25 millirem/year)). The values correspond to screening ``derived 
concentration guidelines'' (DCGLs) for each specific radionuclide based 
on the methodology described in NRC's draft Regulatory Guide 
``Demonstrating Compliance with the Radiological Criteria for License 
Termination'' (DG-4006). After these screening values were published, 
several questions arose concerning conditions or criteria under which 
the screening values would apply. Criteria for determining the 
applicability of these screening values is provided in the following 
section.

Supplementary Information: Sites with surface soil contamination levels 
below those listed in Table 3 of the December 7, 1999, notice will be 
deemed acceptable for release for unrestricted use provided that:
    1. Residual radioactivity has been reduced to levels that are ``as 
low as is reasonably achievable'' (ALARA);
    2. The residual radioactivity is contained in the top layer of the 
surface soil (i.e., a thickness of approximately 15 centimeters);
    3. The unsaturated zone and the groundwater are initially free of 
radiological contamination; and
    4. The vertical saturated hydraulic conductivity at the specific 
site is greater than the infiltration rate. (Refer to NUREG/CR-5512, 
Vol. 1, ``Residual Radioactive Contamination from Decommissioning, 
Technical Basis for Translating Contamination Levels to Annual Total 
Effective Dose Equivalent, Final Report, October 1992'' for additional 
information.) Buildings with surface contamination levels below those 
listed in Table 1 of the November 18, 1998, notice will be deemed 
acceptable for release for unrestricted use provided that:
    1. Residual radioactivity has been reduced to levels that are 
ALARA;
    2. The residual radioactivity is contained in the top layer of the 
building surface (i.e., there is no volumetric contamination);
    3. The fraction of removable surface contamination does not exceed 
0.1. (For cases when the fraction of removable contamination is 
undetermined or higher than 0.1, users may assume, for screening 
purposes, that 100 percent of the surface contamination is removable, 
and therefore the screening values should be decreased by a factor of 
10.)
    For radionuclides not listed in the Tables 1 and 3, the latest 
version of the DandD code may be used, without modification of the 
default values, to derive screening values. However, because the 
current version of DandD (i.e., version 1) is overly conservative, and 
DandD version 2 is under development, NUREG/CR-5512, Vol. 3, ``Residual 
Radioactive Contamination From Decommissioning, Parameter Analysis, 
Draft Report for Comment, October 1999,'' may be used to determine 
acceptable screening values. Specifically, Table 5.19 (using a 
P<INF>crit</INF> = 0.90) may be used for building surface contamination 
screening values and Table 6.91 (using a P<INF>crit</INF> = 0.10) may 
be used for surface soil screening values.
    For site-specific analyses, licensees may use models other than 
DandD to demonstrate compliance with the LTR provided they can 
demonstrate that the model and parameters used in that model are 
appropriate for the site.
    For mixtures of radionuclides in soil or on building surfaces, the 
``sum of fractions'' rule applies (see 10 CFR Part 20, Appendix B, Note 
4).
    The NRC staff intends to include Tables 1 and 3 and these criteria 
governing their use in the Standard Review Plan for decommissioning. 
Comments on this approach may be submitted within 30 days from the date 
of this notice to the Rules and Directives Branch, Division of 
Administrative Services, Office of Administration, U.S. Nuclear 
Regulatory Commission, Washington, DC 20555-0001.
    For further information: Contact Dr. Rateb (Boby) Abu-Eid, 
Environmental and Performance Assessment Branch, Division of Waste 
Management, Office of Nuclear Material Safety and Safeguards, U.S. 
Nuclear Regulatory Commission, Washington, DC 20555-0001. Telephone: 
(301) 415-5811; fax: (301) 415-5398; or email: <a href="/cdn-cgi/l/email-protection#462427230628342568212930"><span class="__cf_email__" data-cfemail="385a595d78564a5b165f574e">[email protected]</span></a>.

    Dated at Rockville, Maryland, this 7th day of June 2000.

    For the Nuclear Regulatory Commission.
Robert A. Nelson,
Acting Chief, Decommissioning Branch, Division of Waste Management, 
Office of Nuclear Material, Safety and Safeguards.
[FR Doc. 00-14839 Filed 6-12-00; 8:45 am]
BILLING CODE 7590-01-P


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