ML041050725
| ML041050725 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/14/2004 |
| From: | Bo Pham NRC/NRR/DLPM/LPD4 |
| To: | Ray H Southern California Edison Co |
| Pham B, NRR/DLPM, 415-8450 | |
| References | |
| GL-96-006, TAC M96862, TAC M96863 EPRI TR-1003098, EPRI TR-1006456, TR-113594 | |
| Download: ML041050725 (4) | |
Text
April 14, 2004 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:
REVIEW OF RESPONSE TO GL 96-06 FOR SAN ONOFRE NUCLEAR GENERATING STATION (SONGS), UNITS 2 AND 3 CONCERNING WATERHAMMER AND TWO-PHASE FLOW (TAC NOS. M96862 AND M96863)
Dear Mr. Ray:
On September 30, 1996, the NRC issued Generic Letter (GL) 96-06, "Assurance of Equipment Operability and Containment Integrity During Design-Basis Accident Conditions," which included a request for licensees to evaluate cooling water systems that serve containment air coolers to ensure that they are not vulnerable to waterhammer and two-phase flow conditions.
Subsequent to issuance of GL 96-06, the Electric Power Research Institute (EPRI) developed and documented an analytical methodology for evaluating the GL 96-06 waterhammer issue in EPRI Technical Reports 1003098 and 1006456 (previously known as EPRI Report TR-113594).
The NRC staff approved this methodology in a safety evaluation (SE) dated April 3, 2002 (included as an Appendix to the EPRI Technical Reports). Section 3.3 of the staffs SE requested licensees who chose to use EPRIs methodology to provide additional information, confirming that the EPRI methodology was properly applied and that plant-specific risk considerations were consistent with the EPRI risk perspective; to justify any proposed exceptions to the EPRI methodology; and to provide any additional information that is required to address the GL 96-06 two-phase flow issue.
Southern California Edison Company (SCE) provided its initial response to GL 96-06 in letters dated October 30, 1996, and February 3, 1997, for SONGS, Units 2 and 3. In response to additional questions, you provided supplemental information in a letter dated October 30, 1998, and indicated that SCE was participating in the EPRI initiative. You also subsequently provided additional information and status updates in letters dated July 30, 2002, November 26, 2002, and July 28, 2003. The information required by Section 3.3 of the staffs SE (referred to in the previous paragraph) was submitted in a letter dated September 29, 2003. However, because SCE used computer codes that have not been reviewed and approved by the NRC in the application of EPRIs methodology, you were asked to provide additional information in order to demonstrate that the analyses were in fact conservative. The NRC staff also requested that SCE explain the basis for load combinations that were used. You provided this additional information in a letter dated December 23, 2003.
Based on our review of the information that was provided, the NRC staff is satisfied with SCEs evaluation and resolution of the GL 96-06 waterhammer and two-phase flow issues. The licensee has provided sufficient confirmation that the EPRI methodology was properly applied
H. Ray for analyzing the GL 96-06 waterhammer issue, and that plant-specific risk considerations are consistent with the EPRI risk perspective; no exceptions to the EPRI methodology were proposed. In order to resolve plant-specific vulnerabilities that were identified, you have implemented a design change to delay restart of the emergency cooling units until after the corresponding component cooling water pump is started following a safety injection actuation signal. Emergency Operating Instructions were also revised to provide enhanced guidelines (based on specific plant parameters) for determining if the non-critical component cooling water loop should be restored following a loss-of-coolant accident in order to address vulnerability of the control element drive mechanism (CEDM) cooling units and the reactor coolant pump (RCP) motor coolers to waterhammer and two-phase flow conditions. Except for vulnerability of the CEDM cooling units and the RCP motor coolers, SCE has determined that containment coolers and associated piping systems at SONGS, Units 2 and 3 are not susceptible to two-phase flow conditions.
While we are satisfied with the licensees resolution of the GL 96-06 waterhammer and two-phase flow issues, we have not performed a detailed quantitative assessment or reviewed the licensees use and application of computer codes for performing these analyses.
Consequently, these areas may be subject to future NRC audit or inspection activities.
In a letter to SCE dated May 1, 2000, the NRC accepted your resolution for the GL 96-06 issue concerning thermal overpressurization. By this letter and evaluation, we accept your resolution for the waterhammer and two-phase flow concerns. This completes our effort relating to GL 96-06 under TAC Numbers M96892 and M96863.
Sincerely,
/RA/
Bo Pham, Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-361 and 50-362 cc: See next page
H. Ray April 14, 2004 for analyzing the GL 96-06 waterhammer issue, and that plant-specific risk considerations are consistent with the EPRI risk perspective; no exceptions to the EPRI methodology were proposed. In order to resolve plant-specific vulnerabilities that were identified, you have implemented a design change to delay restart of the emergency cooling units until after the corresponding component cooling water pump is started following a safety injection actuation signal. Emergency Operating Instructions were also revised to provide enhanced guidelines (based on specific plant parameters) for determining if the non-critical component cooling water loop should be restored following a loss-of-coolant accident in order to address vulnerability of the control element drive mechanism (CEDM) cooling units and the reactor coolant pump (RCP) motor coolers to waterhammer and two-phase flow conditions. Except for vulnerability of the CEDM cooling units and the RCP motor coolers, SCE has determined that containment coolers and associated piping systems at SONGS, Units 2 and 3 are not susceptible to two-phase flow conditions.
While we are satisfied with the licensees resolution of the GL 96-06 waterhammer and two-phase flow issues, we have not performed a detailed quantitative assessment or reviewed the licensees use and application of computer codes for performing these analyses.
Consequently, these areas may be subject to future NRC audit or inspection activities.
In a letter to SCE dated May 1, 2000, the NRC accepted your resolution for the GL 96-06 issue concerning thermal overpressurization. By this letter and evaluation, we accept your resolution for the waterhammer and two-phase flow concerns. This completes our effort relating to GL 96-06 under TAC Numbers M96892 and M96863.
Sincerely,
/RA/
Bo Pham, Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-361 and 50-362 cc: See next page DISTRIBUTION:
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- see previous concurrence Accession No: ML0401050725
- Concurred by memo dtd 3/19/04 OFFICE PDIV-2/PM PDIV/LA**
- DSSA/SPLB PDIV-2/SC**
NAME BPham EPeyton DSolorio SDembek DATE 4/14/04 4/5/04 3/19/04 4/14/04 OFFICIAL RECORD COPY DOCUMENT NAME: C:\\ORPCheckout\\FileNET\\ML041050725.wpd
San Onofre Nuclear Generating Station, Units 2 and 3 cc:
Mr. Raymond Waldo, 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, Radiation Program Director Radiologic Health Branch State Department of Health Services Post Office Box 942732 (MS 178)
Sacramento, CA 94327-7320 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. Dwight E. Nunn, Vice President 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. Joseph J. Wambold, Vice President Southern California Edison Company 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