ML13330B291
| ML13330B291 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/05/1988 |
| From: | Medford M SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8804120341 | |
| Download: ML13330B291 (3) | |
Text
Southem California Edison Company P. 0.
BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 91770 M. 0. MEDFORD TELEPHONE MANAGER OF NUCLEAR ENGINEERING (818) 302-1749 AND LICENSING April 5, 1988 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Engineered Safety Features Single Failure Analysis San Onofre Nuclear Generating Station Unit 1 By letter dated November 20, 1987, SCE provided design descriptions of some of the modifications associated with identified single failure concerns.
Additionally, SCE committed to provide design descriptions for the modifications to resolve the remaining single failure concerns. Accordingly, the enclosure to this letter discusses the modifications associated with the recirculation system single failure concerns.
If you have any questions or require additional information regarding this subject please contact me.
Very truly yours, Enclosure cc: 3. B. Martin, Regional Administrator, NRC Region V F. R. Huey, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3 8804120341 880405 PDR ADOCK 05000206 1 P
CYCLE X MODIFICATIONS DESIGN DESCRIPTIONS FOR RECIRCULATION SYSTEM SAN ONOFRE UNIT 1
Cycle X Modification Design Descriptions for Recirculation System San Onofre Unit 1 Introduction SCE previously committed to upgrade the auxiliary feedwater system (AFW) by automating and integrating the third AFW pump (installed to meet fire protection requirements during the Cycle IX refueling outage). Subsequently, SCE identified single failure susceptibilities of the Reactor Protection System (Steam/Feedwater Flow mismatch trip) and the Engineered Safety Features (main feedwater isolation and recirculation). Design description for the integration of the third AFW pump, the steam/feedwater flow mismatch trip and main feedwater isolation were provided by letter dated November 20, 1987.
Modifications to correct the single failure susceptibilities of the recirculation system are provided below.
I. Realign Power Supply to MOV-1100D
- 1. Change power supply for charging pump suction valve MOV-1100D from MCC-3 (normally train 1) to MCC-2 (train 2).
- 2. All work will be safety-related, Seismic Category A.
II. Recirculation Valve MOV-358 The design description of the modification to assure availability of MOV-358 is not complete at this time. Problems associated with providing an Uninterruptable Power Supply to MOV-358 have prevented completion of the final design at this time. These problems are expected to be resolved shortly and the final design description will be provided by June 1, 1988.