[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
Pcrit = 0.90) may be used for building surface contamination
screening values and Table 6.91 (using a Pcrit = 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: [email protected].
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