ML070660102
| ML070660102 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 03/15/2007 |
| From: | Kalyanam N NRC/NRR/ADRO/DORL/LPLIV |
| To: | Rosenblum R Southern California Edison Co |
| Kalynanam N, NRR/DORL/LP4, 415-1480 | |
| References | |
| TAC MD1713 | |
| Download: ML070660102 (6) | |
Text
March 15, 2007 Mr. Richard M. Rosenblum Senior Vice President and Chief Nuclear Officer Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128
SUBJECT:
SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 3 - CORRECTION LETTER FOR THE ISSUANCE OF RELIEF REQUEST ISI-3-21 RE: THIRD 10-YEAR INSERVICE INSPECTION INTERVAL REQUEST FOR ALTERNATIVE TO THE REQUIREMENTS OF ASME BOILER AND PRESSURE VESSEL CODE (TAC NO. MD1713)
Dear Mr. Rosenblum:
By letter dated May 11, 2006, as supplemented by letter dated November 20, 2006, Southern California Edison Company (the licensee) submitted a request for the use of alternatives to certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, requirements at San Onofre Nuclear Generating Station, Unit 3 (SONGS 3).
Specifically, Relief Request ISI-3-21 requested approval to use alternatives to the requirements of the ASME Code, Section Xl, 1995 Edition through 1996 Addenda, IWA-4000, for repair/replacement activities related to the performance of embedded flaw repairs at SONGS 3 for the third 10-year inservice inspection interval.
The U.S. Nuclear Regulatory Commission (NRC) staff, by letter dated February 7, 2007, authorized Relief Request ISI-3-21 Operating Cycle 14 for SONGS 3.
R. Rosenblum It was subsequently brought to our attention that the February 7, 2007, letter and page 6 of the Safety Evaluation (SE) needed minor corrections. We are enclosing revised page 6 of the SE and page 1 of the cover letter. The changes are identified by a vertical bar on the right. Please replace the affected pages in the February 7, 2007, cover letter and SE with these revised pages.
Sincerely,
/RA/
N. Kalyanam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-362
Enclosure:
Page 1 of the cover letter and Page 6 of the Safety Evaluation cc w/encl: See next page
R. Rosenblum It was subsequently brought to our attention that the February 7, 2007, letter and page 6 of the Safety Evaluation (SE) needed minor corrections. We are enclosing revised page 6 of the SE and page 1 of the cover letter. The changes are identified by a vertical bar on the right. Please replace the affected pages in the February 7, 2007, cover letter and SE with these revised pages.
Sincerely,
/RA/
N. Kalyanam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-362
Enclosure:
Page 1 of the cover letter and Page 6 of the Safety Evaluation cc w/encl: See next page DISTRIBUTION:
PUBLIC RidsNrrPMNKalyanam LPLIV r/f RidsOgcRp RidsAcrsAcnwMailCenter RidsRgn4MailCenter (TPruett)
RidsNrrDorlLpl4 (DTerao) SSheng, NRR RidsNrrLALFeizollahi DCullison, EDO RIV ADAMS Accession No.: ML070660102 OFFICE NRR/LPL4/PM NRR/LPL4/LA NRR/LPL4/BC NAME NKalyanam LFeizollahi DTerao DATE 3/14/07 3/13/07 3/15/07 OFFICIAL AGENCY RECORD
February 7, 2007 Mr. Richard M. Rosenblum Senior Vice President and Chief Nuclear Officer Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128
SUBJECT:
SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 3 - RE: THIRD 10-YEAR INSERVICE INSPECTION INTERVAL REQUEST FOR ALTERNATIVE TO THE REQUIREMENTS OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS BOILER AND PRESSURE VESSEL CODE (TAC NO. MD1713)
Dear Mr. Rosenblum:
By letter dated May 11, 2006, as supplemented by letter dated November 20, 2006, Southern California Edison (SCE, the licensee) submitted a request for the use of alternatives to certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),
Section XI, requirements at San Onofre Nuclear Generating Station, Unit 3 (SONGS 3).
Specifically, Relief Request ISI-3-21 requests approval to use alternatives to the requirements of the ASME Code, Section Xl, 1995 Edition through 1996 Addenda, IWA-4000, for repair/replacement activities related to the performance of embedded flaw repairs at SONGS 3 for the third 10-year inservice inspection interval.
The Nuclear Regulatory Commission (NRC) staff authorizes the alternative proposed by SCE in accordance with 50.55a(a)(3)(i) of Title 10 of Code of Federal Regulations, which states that the proposed alternatives may be used when authorized by the Director of the Office of Nuclear Reactor Regulation if the applicant demonstrates that the proposed alternatives would provide an acceptable level of quality and safety.
Therefore, Relief Request ISI-3-21 is authorized for the Operating Cycle 14 for SONGS 3. Due to the immediate need of this relief request, the NRC staff granted the verbal authorization for the use of this relief request on December 1, 2006.
The Cycle 13 outage inspection confirmed that PWSCC caused the growth of the original flaw to 77.6 percent through-wall, which exceeds the applicability limit of 75 percent specified in WCAP-15987-P, Revision 2. As a result, the licensee used the methodology of ASME Code,Section XI, Appendix C (henceforth referred to as only Appendix C) to calculate the critical flaw size for continued operation through SONGS 3 third 10-year ISI interval. As discussed in the December 23, 2004, SE, the application of Appendix C is limited to a flaw size not greater than 75-percent through-wall thickness. Therefore, the staff determined that the licensees technical basis to use the embedded flaw repair process on RVHP No. 56 was not sufficient for the remainder of the 10-year ISI interval, but was sufficient for one operational cycle.
The approval of Relief Request ISI-3-13 in 2004 was based on the SE determination:
[S]ufficient margin remains in the remaining ligament of 0.128 inch to provide reasonable assurance of the structural integrity of the reactor coolant pressure boundary and an acceptable level of quality and safety, for one operational cycle. The NRC staff bases this conclusion on the following factors: the previously measured crack growth in one operational cycle with measurement uncertainty was 0.09 inch, and the embedded flaw repair method used on RVHP No. 56 effectively eliminates potential crack growth due to PWSCC. This mitigative action limits the crack growth rate to fatigue alone, which is expected to be very small.
This basis applies to the current relief request, ISI-3-21. In this application, a flaw of 77.6 percent through wall would still meet the ASME Code required margins for the crack stability evaluation of the flaw in the repaired RVHP No. 56. Hence, the staff concludes that the issue to be considered here is whether the embedded flaw repair process, which was completed in accordance with WCAP-15987-P, Revision 2, would achieve its objective of isolating the crack from the PWSCC environment.
The licensee reported its UT inspection results in a letter dated November 20, 2006, which indicate that the crack depth growth for the subject flaw is less than 0.02 inch (the UT measurement resolution capability). Based on this, the staff determines that the flaw has been isolated from the PWSCC environment, and the licensees relief request to perform no additional repair beyond the existing weld overlay on the J-weld and penetration OD is justified.
This staff determination also relieves the licensee from executing its commitment quoted in the December 23, 2004, SE:
Prior to the end of the next Unit 3 operating cycle [the Cycle 14 outage] SCE will identify a long-term repair method and implement that repair on [RVHP]
Nozzle 56 during the next 3 refueling outage.
In summary, Relief Request ISI-3-21 is acceptable because the 2006 UT examination demonstrates that the subject crack has no growth and, therefore, has been isolated from the PWSCC environment. The licensees fatigue crack growth analysis, which demonstrates that the repaired SONGS 3 RVHP No. 56 can be operated for 10 years, also supports this determination.
San Onofre Nuclear Generating Station Units 2 and 3 cc:
Mr. Daniel P. Breig Director, Radiologic Health Branch Southern California Edison Company State Department of Health Services San Onofre Nuclear Generating Station P.O. Box 997414, MS 7610 P.O. Box 128 Sacramento, CA 95899-7414 San Clemente, CA 92674-0128 Resident Inspector/San Onofre NPS Mr. Douglas K. Porter, Esquire c/o U.S. Nuclear Regulatory Commission Southern California Edison Company Post Office Box 4329 2244 Walnut Grove Avenue San Clemente, CA 92674 Rosemead, CA 91770 Mayor Mr. David Spath, Chief City of San Clemente Division of Drinking Water and 100 Avenida Presidio Environmental Management San Clemente, CA 92672 P.O. Box 942732 Sacramento, CA 94234-7320 Mr. James T. Reilly Southern California Edison Company Chairman, Board of Supervisors San Onofre Nuclear Generating Station County of San Diego P.O. Box 128 1600 Pacific Highway, Room 335 San Clemente, CA 92674-0128 San Diego, CA 92101 Mr. James D. Boyd, Commissioner Mark L. Parsons California Energy Commission Deputy City Attorney 1516 Ninth Street (MS 31)
City of Riverside Sacramento, CA 95814 3900 Main Street Riverside, CA 92522 Mr. Ray Waldo, Vice President Southern California Edison Company Mr. Gary L. Nolff San Onofre Nuclear Generating Station Assistant Director - Resources P.O. Box 128 City of Riverside San Clemente, CA 92764-0128 3900 Main Street Riverside, CA 92522 Mr. Brian Katz Southern California Edison Company Regional Administrator, Region IV San Onofre Nuclear Generating Station U.S. Nuclear Regulatory Commission P.O. Box 128 611 Ryan Plaza Drive, Suite 400 San Clemente, CA 92764-0128 Arlington, TX 76011-8064 Mr. Steve Hsu Mr. Michael R. Olson Department of Health Services San Diego Gas & Electric Company Radiologic Health Branch 8315 Century Park Ct. CP21G MS 7610, P.O. Box 997414 San Diego, CA 92123-1548 Sacramento, CA 95899 Mr. A. Edward Scherer Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128 March 2006