ML18139A806
| ML18139A806 | |
| Person / Time | |
|---|---|
| Site: | Surry, North Anna  |
| Issue date: | 10/24/1980 |
| From: | Sylvia B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 868, IEB-80-11, NUDOCS 8011100431 | |
| Download: ML18139A806 (2) | |
Text
Vepco VIRGINIA ELECTRIC AND POWER COMPANY
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- dct6ber 24, 1980 Mr. James.P. O'Reilly, Director Office of Inspecti~n & Enforcement U.S. Nuclear Regulatory Commission Serial No.868 PSE&C/RHW,III:b'!!JJ-1-~..__
Docket Nos.
0-280 Region II 50-281 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303
- 38 50-339
Dear Mr. O'Reilly:
License Nos. DPR-32 DPR';"37 NPF-4 NPF-7 EXTENSION OF I.E. BULLETIN 80-11 DEADLINE SURRY POWER STATION UNITS NO. 1 AND 2 NORTH ANNA POWER STATION UNITS NO. 1 AND 2 ll!rl;
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CIJI This letter requests an extension o.f I.E. Bulletin 80-ll's 180-day deadline
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for completion of the masonry wall reevaluation program and submittal of the infor-mation requested in Item 2b of the Bulletin. The information requested in Items 1, 2a, and 3 was submitted in our letter of July 7, 1980, Serial No. 434/050880 within 60 days of the date of the Bulletin as required. All masonry walls identified as being within the scope of the reevaluation program required by the Bulletin have had as-built drawings prepared to provide the nec*essary details for analysis and reevalu-ation.
An Interim Report will be submitted to the NRC within 180 days of the date of the Bulletin, on or before November 4, 1980.
This report will update the response provided in the 60-day report, include the reevaluation criteria being applied and present the results for those walls where analysis has been completed. With this report, all information required by the Bulletin will have been submitted with the exception of justification for the criteria used and the results of the reevaluation program which is still in progress. This information will be submitted in our Final Report when the reevaluation program is complete.
Our reevaluation program for the masonry walls is a multi-level program oriented toward several methods of analysis.
- Walls are being evaluated initially based on conservative criteria to identify areas where more complex analyses are warranted and to identify walls which can be upgraded by design modifications while more extensive analyses are being undertaken.
- This approach includes initial stress evaluations that are preliminary in nature and for which the results generally differ noticeably from final calculations. The des_igil of modifications for walls which appear over-stressed based on initial evaluations constitutes a parallel path approach to reevalua-tion and design modification.
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- Even though more modifications would be indicated from initial evaluations than final cilculations, we have found that a parallel approach, with structural modifications being designed on preliminary evaluations while analysis continues to conclusion, r~sults in the most expeditious upgrading of plant structures and provides the most expeditious schedule for achieving compliance with the Bulletin.
This parallel effort may result in the installatio*n of modifications by the time that final calculations are completed.
The installed modifications to masonry walls will remain even if final calculations show they are not required. If during the course of the reevaluation it can be conclusively shown that the operability of any safety related system is in jeopardy, the appropriate actions will be taken to meet the applicable Technical Specification Action Statement as required by the Bulletin.
We believe that the experience gained to date with the pipe stress analyses performed in response to other bulletins has provided us with a methodology applica-ble to this effort. The expeditious.installation of modifications will fully meet NRC requirements with the only disadvantage being the likelihood that modifications will prove to be unnecessary by final detailed analyses.
Seismic analyses of masonry walls at Surry Power Station will be based on the use of seismic response and amplified response spectra of structures determined
- from soil structure interaction analyses (SSI-ARS) techniques, where appropriate.
The SSI-ARS weri developed in conjunction with the pipe reanalyses efforts initiated in 1979 to meet NRC requirements.
Our efforts since the 60-day report have been directed towards completing the as-built documentation for the masonry walls, researching available information to develop the reevaluation criteria and applicable procedures, and implementing the reanalyses progra~. Analysis has been completed and has demonstrated acceptability of approximately one-third of the walls which are in the reevaluation program.
Due to the extensive analysis yet to be performed and the limited time remain-ing until the November 4 date for submittal of the response required within 180 days, Vepco is requesting that an extension be granted for completion of the reevaluation program.
Based on our current schedule and available manpower, the reanalysis is scheduled to be completed by the end of July 1981.
If you have any questions, please contact us.
cc:
Mr. Victor Stello, director Very truly yours,
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B. R. "Sylvia Manager - Nuclear Opeiations & Maintenance Office of Inspection & Enforcement Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation