ML19322E584
| ML19322E584 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 03/25/1980 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-79-14, NUDOCS 8003280460 | |
| Download: ML19322E584 (3) | |
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Docket No. 50-346 lr
/ TOLEDO License No. NPF-3 gggg Serial No. 1-121 RcH4eo P CAOUSE vre pri anat NuCwer March 25, 1980
- S a m' Mr. James C. Keppler Regional Director, Reg' ion III Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137
Dear Mr. Keppler:
IE Bulletin No. 79-14, dated July 2, 1979, requested that we develop and implement an inspection program to verify that the Davis-Besse Nuclear Power Station Unit 1 seismic analysis input of safety related piping systems conforms to the actual field conditions.
On October 19, 1979, we submitted to you the results of our detailed engineering reviews for normally excessible safety related piping. As a part of that submittal, we transmitted our schedule for follow-on ana-lytical work required under Item No. 4B of the Bulletin. As work pro-gressed, it became apparent that we would not be able to meet our original schedule. Attached is the current status of the follow-on analytical work required under Item No. 4B and our revised schedule for the completion of this effort.
Yours very truly,
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U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Division of Reactor Operation Inspection Washington, D. C.
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U.S. Nuclear Regulatory Commission '/
5 Office of Nuclear Reactor Regulation Division of Operating Reactors
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20555 THE TOLEGO EDISON COMPANY EDISON PLAZA 300 MAOISON AVENUE TOLEDO, OHIO 43652 80032804-60 i
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Seismic Analys's For As-Built i
Safety Related Piping Systems Response to NRC IE Bulletin No. 79-14 Davis-Besse Nuclear Power Station Unit 1 NRC IE Bulletin 79-14, dated July 2, 1979, Revision 1, dated July 18, 1979, Supple =ent 1, dated August 15, 1979, and Supplement 2, dated September 7,1979, require all power reactor facility licensees to verify that the seismic analysis of safety-related piping systems applies to the actual as-built configuration of systems. The action items identified in the Bulletin apply to all safety-related piping, 2-1/2 inches in diameter and greater, and to Seismic Category I piping, regardless of size, which was analyzed by computer.
The response to Item 1 of the Bulletin was submitted on August 1,1979 (Serial No.1-81).
A partial response to Item 2 of the Bulletin, describing the inspection procedures and liscrepancies reviewed prior to Septenber 30, 1979 for normally accessible piping systems, as defined by the Bulletin, was submitted on October 1,1979 (Serial No.1-93).
The complete response to Item 2 of the Bulletin and a partial response to Ites 4 was submitted on October 19, 1979 (Serial No. 1-95).
The pirtial response to Item 4 included the evaluation of the identified nonconformances upon system operability and an estimated date for completion of the reanalysis of the piping and supports for the normally acce ssible systems.
The reanalysis of the piping and supports has involved more detailed stress reanalysis than originally anticipated. This additional reanalysis has resulted in not being able to meet our original schedule for completing this work. This report presents the current status of our reanalysis of the piping and supports for the normally accessible areas and our revised schedule for completing this work.
The completed detailed engineering review of all discrepancies has shown that the operability of safety-related systems is unaffected. In the reanalysis performed thus far, no deficiency has been discovered that has adversely affected the operability of any safety-related system.
If, at any time during the remaining reanalysis, there results a conclusion that a deficiency exists in either the piping or its supporting system that affects system operability, applicable Technical Specification action will be taken.
In our previous partial response to Item 4 of the Bulletin, a tabulation was provided which identified the discrepancies by stress calculation number and pipe support or anchor number. In this table, a description of the stress calculation reanalysis requ red to verify the adequacy of the as-built configuration of the piping and supporting systems was provided.
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At that time, it was anticipated that a tot'al of 89 stress calculations would require complete computer reanalysis. An additional 98 stress calculations were to require a simple hand calculation to resolve the discrepancies, and 33 calculations did not require any piping reanalysis. During the course of the reanalysis effort, a number of stress calculations were re-evaluated by the stress analyst based on the results of the calculations performed thus far and it was determined that a more extensive computer analysis would be required. Currently, it is planned to perform a complete computer rear.alysis for 140 stress calculations and a simple hand calculation for an additional 47 stress calculations. At this time, we have completed 60% of the computer reanalysis.
The tabulation from the previous response in our October 19, 1979 letter to Item 4 of the Bulletin identified 552 pipe supports and anchors having discrepancies between the design drawing and the as-built configuration. Many of these will require a structural reanalysis to verify the adequacy of the support; many others will require only a minor drawing revision.
In addition, as the stress calculations are reanalyzed structural analysis of additional supports may be required if the support loads increase.
The final number of supports to to be reanalyzed will not be known until all stress calculations have been rerun. At this time, approximately 300 pipe support calculations have been completed based upon the revised stress analysis and the identified walkdown discrepancies.
At this time, the earliest expected completion date for reanalysis of the piping and support systems for the normally accessible piping is June 2,1980, with submittal of the results of the reanalysis scheduled for June 16, 1980.
The current completion date for revising engineering documents to reflect as-built conditions in the station is September 1, 1980.
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