Southern California Edison Company and San Diego Gas and Electric Company, the City of Riverside, California and the City of Anaheim, California, San Onofre Nuclear Generating Station, Units 2 and 3; Environmental Assessment and Finding of No Significant Impact

The U.S. Nuclear Regulatory Commission (NRC) is considering issuance of an exemption from Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix G for Facility Operating License No. NPF-10 and NPF-15, issued to Southern California Edison (the licensee), for operation of the San Onofre Nuclear Generating Station, Units 2 and 3 (SONGS 2 and 3), located in San Diego County, California. Therefore, as provided by 10 CFR 51.21 and 51.33, the NRC is issuing this environmental assessment and finding of no significant impact.

Environmental Assessment

Identification of the Proposed Action

By letter dated January 28, 2005, the licensee submitted a license amendment request where, among other changes, the licensee requested the use of an alternate methodology for calculating the stress intensity factor K_Im due to internal pressure loading. As required by the safety evaluation on topical report Combustion Engineering (CE) Topical Report NPSD-683-A, Revision 6, dated March 16, 2001, the licensee, by its supplement dated January 12, 2006, included a request for an exemption from the requirements of 10 CFR Part 50, Appendix G for pressure temperature (P-T) limits since the alternate methodology applies the CE Nuclear Steam Supply System method for calculating K_Im stress intensity values.

The proposed action would exempt the licensee from certain requirements of Appendix G to 10 CFR Part 50 to allow the application of the methodology in CE NPSD-683-A, Revision 6, “The Development of a RCS [Reactor Coolant System] Pressure and Temperature Limits Report for the Removal of P-T Limits and LTOP [Low-Temperature Overpressure Protection] Setpoints from the Technical Specifications,” for the calculation of flaw stress intensity factors due to internal pressure loadings (K_Im).

The Need for the Proposed Action

In the associated exemption, the staff has determined that, pursuant to 10 CFR 50.12(a)(2)(ii), the application of the regulation in the particular circumstances is not necessary to achieve the underlying purpose of the rule, based on the alternative methodology proposed in the licensee's amendment request. The proposed action would revise the currently-approved methodology for P-T limit calculations to incorporate the methodology approved for use in CE NPSD-683-A, Revision 6. The topical report allows the use of an alternate methodology to calculate the flaw stress intensity factors due to internal pressure loadings (K_Im). The exemption is needed because the methodology in CE NPSD-683-A, Revision 6, could not be shown to be conservative with respect to the methodology for the determination of K_Im provided in Editions and Addenda of ASME Code, Section XI, Appendix G, through the 1995 Edition and 1996 Addenda (the latest Edition and Addenda of the ASME Code which had been incorporated into 10 CFR 50.55a at the time of the staff's review of CE NPSD-683-A, Revision 6). Therefore, along with the supplement dated January 12, 2006, the licensee submitted an exemption request, consistent with the requirements of 10 CFR 50.60, to apply the K_Im calculational methodology of CE NPSD-683-A, Revision 6, as part of the SONGS 2 and 3 pressure temperature limit report (PTLR) methodology.

Environmental Impacts of the Proposed Action

The NRC has completed its evaluation of the proposed action and concludes that the exemption described above would provide an adequate margin of safety against brittle failure of the reactor pressure vessel at SONGS 2 and 3. The details of the staff's safety evaluation will be provided in the exemption to Appendix G, which will allow the use of the methodology in Topical Report CE NPSD-683-A, Revision 6, to calculate the flaw stress intensity factors due to internal pressure loadings (K_Im), that will be issued in a future letter to the licensee.

The proposed action will not significantly increase the probability or consequences of accidents, no changes are being made in the types of effluents that may be released off site, and there is no significant increase in occupational or public radiation exposure. Therefore, there are no significant radiological environmental impacts associated with the proposed action.

With regard to potential nonradiological impacts, the proposed action does not have a potential to affect any historic sites. It does not affect nonradiological plant effluents and has no other environmental impact. Therefore, there are no significant nonradiological environmental impacts associated with the proposed action.

Accordingly, the NRC concludes that there are no significant environmental impacts associated with the proposed action.

Environmental Impacts of the Alternatives to the Proposed Action

As an alternative to the proposed action, the staff considered denial of the proposed action (i.e., the “no-action” alternative). Denial of the application would result in no change in current environmental impacts. The environmental impacts of the proposed action and the alternative action are similar.

Alternative Use of Resources

The action does not involve the use of any different resources than those previously considered in the Final Environmental Statement for the SONGS 2 and 3 dated May 12, 1981.

Agencies and Persons Consulted

On March 28, 2006, the staff consulted with the California State official, Steve Hsu of the Department of Health Services, Radiologic Health Branch, regarding the environmental impact of the proposed action. The State official had no comments.

Finding of No Significant Impact

On the basis of the environmental assessment, the NRC concludes that the proposed action will not have a significant effect on the quality of the human environment. Accordingly, the NRC has determined not to prepare an environmental impact statement for the proposed action.

For further details with respect to the proposed action, see the licensee's exemption letter dated January 28, 2005, as supplemented by letter dated January 12, 2006. Documents may be examined, and/or copied for a fee, at the NRC's Public Document Room (PDR), located at One White Flint North, Public File Area O1 F21, 11555 Rockville Pike (first floor), Rockville, Maryland. Publicly available records will be accessible electronically from the Agencywide Documents Access and Management System (ADAMS) Public Electronic Reading Room on the Internet at the NRC Web site, http://www.nrc.gov/reading-rm/adams.html. Persons who do not have access to ADAMS or who encounter problems in accessing the documents located in ADAMS, should contact the NRC PDR Reference staff by telephone at 1-800-397-4209 or 301-415-4737, or by e-mail to pdr@nrc.gov.