ML052430666
| ML052430666 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/26/2005 |
| From: | Donohew J NRC/NRR/DLPM/LPD4 |
| To: | Ray H Southern California Edison Co |
| Donohew J N, NRR/DLPM,415-1307 | |
| References | |
| TAC MC5522, TAC MC5523 | |
| Download: ML052430666 (5) | |
Text
September 26, 2005 Mr. Harold B. Ray Executive Vice President Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128
SUBJECT:
SAN ONOFRE NUCLEAR GENERATING STATION (SONGS), UNITS 2 AND 3 RE: CORRECTION TO RELAXATION OF THE REQUIREMENTS OF ORDER EA-03-009 REGARDING REACTOR PRESSURE VESSEL HEAD INSPECTIONS (TAC NOS. MC5522 AND MC5523)
Dear Mr. Ray:
In its letter dated June 27, 2005, the Nuclear Regulatory Commission (NRC) staff authorized, pursuant to Section IV.F of the First Revised NRC Order EA-03-009 dated February 20, 2004, for SONGS, Units 2 and 3, the proposed alternative inspection submitted in your letter dated January 3, 2005 (Agencywide Documents Access and Management System Accession No. ML050050216). The proposed alternative inspection is authorized for the 91 control element drive mechanisms (CEDMs) at SONGS, Unit 2, and the 91 CEDMs at SONGS, Unit 3, for each operating cycle, for which the First Revised NRC Order EA-03-009 dated February 20, 2004, remains in effect, and is subject to the condition stated in the letter dated June 27, 2005.
In its letter, the NRC staff stated that each operating cycle for which the alternative inspection was authorized would be not greater than 21 months. This statement is incorrect in that 21 effective full power months (EFPMs) should have been stated because the time period was based on the 1.75 effective full power years (EFPYs) in the table on page 6 of the safety evaluation (SE) attached to the June 27, 2005 letter. To correct this error, I have enclosed pages 7 and 8 of that SE which have the correct reference to 21 EFPMs, and a vertical bar on the right-hand side of the page showing where the change was made.
Sincerely,
/RA/
Jack Donohew, Senior Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-361 and 50-362
Enclosure:
Pages 7 and 8 of Safety Evaluation dated June 27, 2005 cc w/encl: See next page
September 26, 2005 Mr. Harold B. Ray Executive Vice President Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128
SUBJECT:
SAN ONOFRE NUCLEAR GENERATING STATION (SONGS), UNITS 2 AND 3 RE: CORRECTION TO RELAXATION OF THE REQUIREMENTS OF ORDER EA-03-009 REGARDING REACTOR PRESSURE VESSEL HEAD INSPECTIONS (TAC NOS. MC5522 AND MC5523)
Dear Mr. Ray:
In its letter dated June 27, 2005, the Nuclear Regulatory Commission (NRC) staff authorized, pursuant to Section IV.F of the First Revised NRC Order EA-03-009 dated February 20, 2004, for SONGS, Units 2 and 3, the proposed alternative inspection submitted in your letter dated January 3, 2005 (Agencywide Documents Access and Management System Accession No. ML050050216). The proposed alternative inspection is authorized for the 91 control element drive mechanisms (CEDMs) at SONGS, Unit 2, and the 91 CEDMs at SONGS, Unit 3, for each operating cycle, for which the First Revised NRC Order EA-03-009 dated February 20, 2004, remains in effect, and is subject to the condition stated in the letter dated June 27, 2005.
In its letter, the NRC staff stated that each operating cycle for which the alternative inspection was authorized would be not greater than 21 months. This statement is incorrect in that 21 effective full power months (EFPMs) should have been stated because the time period was based on the 1.75 effective full power years (EFPYs) in the table on page 6 of the safety evaluation (SE) attached to the June 27, 2005 letter. To correct this error, I have enclosed pages 7 and 8 of that SE which have the correct reference to 21 EFPMs, and a vertical bar on the right-hand side of the page showing where the change was made.
Sincerely,
/RA/
Jack Donohew, Senior Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation DISTRIBUTION Docket Nos. 50-361 and 50-362 PUBLIC PDIV-2 r/f
Enclosure:
Pages 7 and 8 of Safety Evaluation RidsNrrDlpmLpdiv (HBerkow) dated June 27, 2005 RidsNrrDlpmLpdiv2 RidsNrrPMJDonohew cc w/encl: See next page RidsNrrLALFeizollahi RidsAcrsAcnwMailCenter RidsOgcRp RidsRgn4MailCenter (TPruett)
RidsNrrDlpmDpr TChan DCollins ACCESSION NO: ML052430666 NRR-106 OFFICE PDIV-2/PM PDIV-2/LA EMCB/SC PDIV-2/SC(A)
PDIV-2/PD NAME JDonohew LFeizollahi TChan DCollins HBerkow DATE 09/14/05 09/9/05 09/19/05 09/23/05 09/26/05 OFFICIAL RECORD COPY Note 1:
Stress intensity is less than the threshold of 9 Mpa/m [Kth from page 4-5 of the licensees letter dated February 28, 2004] and therefore will not propagate towards the bottom of the weld.
The results above illustrate the conservatism in the licensees requested relaxation, as the calculated inspection frequency is longer than a SONGS operating cycle. The operating cycle for each SONGS Unit is 19.5 months. The licensees calculations for the relaxation request based on as-designed weld sizes will support a period of 1.75 EFPYs, or 21 effective full power l
months (EFPMs).
l The licensees analysis in WCAP-15819, Rev. 1 used the crack growth formula in Electric Power Research Institute (EPRI) Report Material Reliability Program (MRP) report MRP-55, Material Reliability Program (MRP) Crack Growth Rates for Evaluating Primary Water Stress Corrosion Cracking (PWSCC) of Thick Wall Alloy 600 Material (MRP-55), Revision 1.
However, the NRC staff has not yet made a final determination on the acceptability of the subject industry report. Should the NRC staff determine the crack growth formula used by the licensee to be unacceptable, the licensee will be required to revise its analysis to incorporate an acceptable crack growth formula as described below. In agreement with this, the licensee included in their submittal dated January 3, 2005, the following condition:
If the NRC staff finds that the crack-growth formula in industry report MRP-55 is unacceptable, then SCE will revise its analysis that justifies relaxation of the Order within 30 days after the NRC informs the licensee of an NRC-approved crack growth formula. If SCEs revised analysis shows that the crack growth acceptance criteria are exceeded prior to the end of the current operating cycle, SCE will consider Relaxation Request 3 [licensees January 3, 2005, submittal]
to be rescinded and, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, SCE will submit to the NRC written justification for continued operation. If the revised analysis shows that the crack growth acceptance criteria are exceeded during the subsequent operating cycle, SCE will, within 30 days, submit the revised analysis for NRC review. If the revised analysis shows that the crack growth acceptance criteria are not exceeded during either the current operating cycle or the subsequent operating cycle, SCE will, within 30 days, submit a letter to the NRC confirming that its analysis has been revised. Any future crack-growth analyses performed for this and future cycles for RPV head penetrations will be based on a crack growth rate formula that is acceptable to the NRC.
As an added conservatism, the licensee stated that the crack growth curves do not include the time that would be required for an axial crack to propagate through the attachment weld and result in a leakage path. Additional operating time would be required for a safety concern (ejection of a nozzle or substantial corrosion of the low-alloy steel RPV head) to develop as a result of that leak. Therefore, it would take more than one operating cycle for a postulated flaw in the uninspected region to develop into a safety concern.
The licensee stated that the threaded portion of the extension shaft guide cone would serve to retain potential loose parts resulting from a circumferential crack in the uninspected area. A postulated 360-degree through-wall crack in the narrow un-inspected annulus above the guide cone threads could result in separation of the guide cone from the penetration. However, the licensee stated the guide cone would be retained by the control element assembly (CEA) shroud and associated CEA extension shaft. This condition would not interfere with CEA function or any other reactor coolant system function, and would be readily observed in the subsequent refueling outage.
Based upon the information above, the staff finds that the licensee has demonstrated good cause for the relaxation and that the proposed alternative examination is acceptable as it provides reasonable assurance of the structural integrity of the RPV head, VHP nozzles and welds. Furthermore, inspections to comply with the Order requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.0 CONCLUSION
The staff concludes that the licensees proposed alternative examination for each of the 91 CEDMs for SONGS, Units 2 and 3 from 2 inches above the J-groove weld to the level identified below:
CEDM # 1 0.44 inches below the bottom of the weld, CEDM #s 2 through 35 0.43 inches below the bottom of the weld, CEDM #s 36 through 87 0.42 inches below the bottom of the weld, and CEDM #s 88 through 91 0.35 inches below the bottom of the weld, provides reasonable assurance of the structural integrity of the RPV head, VHP nozzles and welds. Furthermore, inspections of these VHP nozzles in accordance with Section IV, paragraph C.(5)(b), of the Order dated February 20, 2004, would result in hardship without a compensating increase in the level of quality and safety. Therefore, pursuant to Section IV, paragraph F, of the Order dated February 20, 2004, the staff authorizes the proposed alternative inspection for the 91 CEDMs at SONGS, Unit 2, and the 91 CEDMs at SONGS, Unit 3, for each operating cycle, not greater than 21 EFPMs, for a time period for which the l
Order dated February 20, 2004, remains in effect, subject to the following condition:
If the NRC staff finds that the crack-growth formula in industry report MRP-55 is unacceptable, then SCE will revise its analysis that justifies relaxation of the Order within 30 days after the NRC informs the licensee of an NRC-approved crack growth formula. If SCEs revised analysis shows that the crack growth acceptance criteria are exceeded prior to the end of the current operating cycle, SCE will consider Relaxation Request 3 to be rescinded and, within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, SCE will submit to the NRC written justification for continued operation. If the revised analysis shows that the crack growth acceptance criteria are exceeded during the subsequent operating cycle, SCE will, within 30 days, submit the revised analysis for NRC review. If the revised analysis shows that the crack growth acceptance criteria are not exceeded during either the current operating cycle or the subsequent operating cycle, SCE will, within 30 days, submit a letter to the NRC confirming that its analysis has been revised. Any future crack-growth analyses performed for this and future cycles for RPV head penetrations will be based on a crack growth rate formula that is acceptable to the NRC.
Principal Contributor: J. Collins Date: June 27, 2005
August 2005 San Onofre Nuclear Generating Station Units 2 and 3 cc:
Mr. Daniel P. Breig, Plant Manager Nuclear Generation Southern California Edison Company San Onofre Nuclear Generating Station P. O. Box 128 San Clemente, CA 92674-0128 Mr. Douglas K. Porter Southern California Edison Company 2244 Walnut Grove Avenue Rosemead, CA 91770 Mr. David Spath, Chief Division of Drinking Water and Environmental Management P. O. Box 942732 Sacramento, CA 94234-7320 Chairman, Board of Supervisors County of San Diego 1600 Pacific Highway, Room 335 San Diego, CA 92101 Eileen M. Teichert, Esq.
Supervising Deputy City Attorney City of Riverside 3900 Main Street Riverside, CA 92522 Mr. Gary L. Nolff Power Projects/Contracts Manager Riverside Public Utilities 2911 Adams Street Riverside, CA 92504 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 Mr. Michael Olson San Diego Gas & Electric Company P.O. Box 1831 San Diego, CA 92112-4150 Mr. Ed Bailey, Chief Radiologic Health Branch State Department of Health Services Post Office Box 997414 (MS7610)
Sacramento, CA 95899-7414 Resident Inspector/San Onofre NPS c/o U.S. Nuclear Regulatory Commission Post Office Box 4329 San Clemente, CA 92674 Mayor City of San Clemente 100 Avenida Presidio San Clemente, CA 92672 Mr. James T. Reilly Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92674-0128 Mr. James D. Boyd, Commissioner California Energy Commission 1516 Ninth Street (MS 31)
Sacramento, CA 95814 Mr. Ray Waldo, Vice President Southern California Edison Company San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92764-0128 Mr. Brian Katz Vice President, Nuclear Oversight and Regulatory Affairs.
San Onofre Nuclear Generating Station P.O. Box 128 San Clemente, CA 92764-0128 Mr. Steve Hsu Department of Health Services Radiologic Health Branch MS 7610, P.O. Box 997414 Sacramento, CA 95899