ML13322B144
| ML13322B144 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/02/1990 |
| From: | Nandy F SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 NUDOCS 9005040264 | |
| Download: ML13322B144 (2) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 F. R. NANDY TELEPHONE MANAGER OF NUCLEAR LICENSING May 2, 1990 (714) 587-5400 U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D. C. 20555 Gentlemen:
Subject:
Docket No. 50-206 ECCS Single Failure Analysis San Onofre Nuclear Generating Station, Unit 1 The purpose of this letter is to inform you that we will need additional time to complete the emergency core cooling system (ECCS) single failure analysis.
We committed to redo the 1976 NUS single failure analysis within nine months from restart from the Cycle 10 refueling outage. This commitment was made in our letter dated March 17, 1989, "Technical Issues Impacting San Onofre Unit I Restart."
The commitment was the result of our evaluation of a single failure deficiency in the component cooling water system identified during an instrument air study. However, several conditions have impacted this schedule:
0 Other critical work to support continued plant operation and preparation of the accelerated Cycle 11 outage design changes required rescheduling of significant engineering and analysis resources; 0
The scope of the single failure analysis has increased as a result of lessons learned from daily operation, e.g., separate boundary valve analysis resulting from licensee event reports; and a
Unanticipated modifications required in the midcycle outage in Cycle 10, e.g., the Recirculation System backup nitrogen changes, required additions and revisions to the single failure analysis.
We have recently issued a draft single failure analysis for interdisciplinary review. We will submit a letter to inform you of its completion by July 31, 1990, and will provide a copy of the analysis report for your information at that time.
Integrated Resolution of SEP Topic VI-7.C.2 and Regulatory Guide 1.97 The ECCS single failure analysis provides the basis for the integrated resolution of remaining issues from SEP Topic VI-7.C.2 and Regulatory
'005040264 900502 D01 PDR ADOCK 05000206 P
PDC 1n
Document Control Desk May 2, 1990 Guide 1.97 (RG 1.97).
In our letter dated June 3, 1989, "Integration of SEP Topic VI-7.C.2, 'Failure Mode Analysis (ECCS),' and Regulatory Guide 1.97 Separation Issues," we committed to provide an integrated resolution of open SEP Topic VI-7.C.2 and RG 1.97 issues for post-accident safe shutdown equipment to cover the single failure, environmental qualification, and electrical separation issues within six months of completion of the ECCS single failure analysis.
For example, the ECCS single failure analysis may determine modifications are necessary to the power supplies for the RPS and ESF components. This would affect the separation of power supplies issue remaining from the SEP topic.
The accelerated Cycle 11 refueling outage begins at the end of June 1990.
Modifications implemented during that outage will require further revisions to the single failure analysis which will be completed by July 31, 1990. In addition, the outage will delay the availability of resources to resolve remaining SEP and RG 1.97 open items. Therefore, we will submit the integrated resolution by June 30, 1991.
Schedule for Implementation of Modifications We committed in our letter dated October 2, 1989, "Full Term Operating License Open Items," to implement any modifications to resolve remaining open items as a result of the integrated resolution of these issues by the end of the Cycle 12 refueling outage. The revised analysis schedule will not impact the overall implementation schedule.
If you have any questions or comments, please call me.
Sincerely cc:
J. B. Martin, Regional Administrator, NRC Region V C. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3 bcc:
(See attached sheet)