ML18153D374
| ML18153D374 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 06/29/1993 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| REF-GTECI-AE, REF-GTECI-B-46, TASK-A-46, TASK-OR 92-763, GL-87-02, GL-87-2, NUDOCS 9307060123 | |
| Download: ML18153D374 (3) | |
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VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 June 29, 1993 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Serial No.
NL&P/ETS Docket Nos.92-763 R1 50-280 50-281 50-338 50-339 License Nos. DPR-32 DPR-37 NPF-4 NPF-7 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 NORTH ANNA POWER STATION UNITS 1 AND 2 SUPPLEMENTAL RESPONSE TO GENERIC LETTER 87-02 IMPLEMENTATION OF GIP GUIDANCE In the NRC's Safety Evaluation Report (SER), dated November 20, 1992, on our response to Supplement No. 1 of Generic Letter (GL) 87-02, "Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors, Unresolved Safety Issue (USI) A-46," dated September 18, 1992, the staff raised a concern regarding implementation of the Generic Implementation Procedure (GIP) guidance.
Of specific concern to the NRG was whether we were committing to the complete implementation of all provisions of the guidance section in the GIP and, if not, what our process would be for notifying the staff of deviations from the guidance. Additionally, the SER stated that if we did not commit to full implementation of the SQUG commitments and implementation guidelines, or acceptable alternative criteria and procedures, the NRG Staff could not agree to Virginia Electric and Power Company changing its licensing basis to use the GIP methodology.
Our implementation of the GIP guidance will be in accordance with Part 1, Section 1.3 of the GIP, Rev. 2 (corrected February 14, 1992), which was accepted by the NRG staff in its Supplemental SER-2, dated May 22, 1992. The statement in our September 18, 1992 letter that "Virginia Electric and Power Company will generally conform to the GIP implementation guidance... " was intended to note that a few deviations from GIP-2 and Supplemental SER-2 may be necessary during the implementation phase of the USI A-46 program. In accordance with the guidance of the GIP, we will notify the Staff of each deviation as soon as practicable, but no later than the submittal of our final summary reports. Generally, this means that significant or programmatic deviations will be submitted expeditiously and minor or insignificant deviations will be submitted in our final summary report. This approach is consistent with the GIP.
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Accordingly, we are notifying you of two specific programmatic exceptions from the GIP that we now intend to take in our implementation of the USI A-46 program. They are as follows:
When a component on the safe shutdown list is seismically qualified per the criteria of RG 1.100, Revision 1, and IEEE 344-1975, we may use this qualification in lieu of conducting an evaluation per GIP-2. This will also make it unnecessary to conduct the anchorage/mounting evaluations per GIP-2, if it is confirmed that the equipment was tested per IEEE 344-1975 and the mounting of the equipment during the seismic tests is the same as the mounting condition in the plant. We believe this is consistent with the Staff position stated in item 2 of Section 1.2.3 of Supplemental SER-2, which states that "... the staff agrees that the seismic qualification requirements (RG 1.100, Revision 1) will resolve the USI A-46 requirements for that equipment."
Previously performed anchorage calculations may be used where possible. A review of these calculations will be performed to ascertain that the seismic accelerations previously used are equal to or greater than the accelerations from the approved in-structure spectra for the USI A-46 program.
If these calculations conform to the licensing or design basis criteria and methodologies of North Anna and Surry Power Stations, no revisions will be made to bring them into conformance with the GIP-2 and Supplemental SER-2 criteria and methodologies, unless our walkdowns or reviews indicate non-conformance to the design basis configurations or criteria.
We believe that implementing the USI A-46 program consistent with Revision 2 of the GIP and Supplemental SER-2 meets the staff's position to fully implement both the SQUG commitments and implementing guidance. Therefore, we interpret the staff's SER as acceptance of our proposed revision of the plant specific licensing basis requested in our September 18, 1992 letter. As stated in that letter, we intend to revise our licensing basis according to 1 O CFR 50.59 to reflect the acceptability of the GIP methodology as an alternate qualification method, for new and replacement equipment, as well as for existing electrical and mechanical equipment, before receipt of a final plant-specific Safety Evaluation Report resolving USI A-46.
In response to your question regarding the response spectra for North Anna, we are currently developing realistic, median-centered in-structure response spectra for use in the IPEEE-Seismic Margin Assessment program. We may use scaled median-centered spectra as an option, in-lieu of the conservative design spectra for our USI-A46 program. The development of the median-centered spectra is expected to be completed by September 1993. As stated in the Supplemental SER-2, a prior review of the North Anna in-structure spectra was not required by the staff. Therefore, we intend to provide the spectra selected for use in the USI A-46 program with the final summary report.
Additionally, we want to further clarify the methodology used to generate the in-structure response spectra stated in our September 18, 1992 letter for Surry. This clarification is provided because our 120- day response, dated September 18, 1992,
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could have led your staff to believe that three orthogonal time-histories were used simultaneously as ground motion input. The analyses originally prepared for the plant by Stone & Webster, and recently by EOE for four buildings, employed two directional time-history inputs (one vertical and one horizontal) at a time.
By repeating the analyses in the vertical and the second horizontal direction, in-structure response spectra were calculated for all three orthogonal directions. This method is consistent with the Surry Updated Final Safety Analysis Report.
Should you have any additional questions or concerns, please contact us.
Very truly yours,
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\\J W. L. Stewart Senior Vice President - Nuclear cc:
U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, N. W.
Suite 2900 Atlanta, Georgia 30323 Mr. M. W. Branch NRC Senior Resident Inspector Surry Power Station Mr. D. R. Taylor NRC Resident Inspector North Anna Power Station