ML13324A705
| ML13324A705 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/30/1985 |
| From: | Medford M SOUTHERN CALIFORNIA EDISON CO. |
| To: | Zwolinski J Office of Nuclear Reactor Regulation |
| References | |
| TAC-65271, NUDOCS 8509040172 | |
| Download: ML13324A705 (2) | |
Text
Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 M.O.MEDFORD TELEPHONE MANAGER, NUCLEAR LICENSING (818) 302-1749 August 30, 1985 Director, Office of Nuclear Reactor Regulation Attention: 3. A. Zwolinski, Chief Operating Reactors Branch No. 5 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Technical Specification 3.1.2 Operating Status of Reactor Coolant System Equipment San Onofre Nuclear Generating Station Unit 1 This letter is to notify you of a potential discrepancy between the San Onofre Unit 1 Technical Specifications and the plant's safety analysis assumptions and to describe the steps taken, or to be taken, by Southern California Edison (SCE) to resolve the potential discrepancy.
The information below is being provided pursuant to recent conversations between SCE and the NRC staff on this subject.
The existing San Onofre Unit 1 Technical Specifications permit plant operation in Mode 3 with only one reactor coolant pump in operation. However, according to Westinghouse, the original safety analysis for control rod ejection for San Onofre Unit 1 had assumed that two reactor coolant pumps were running and the analysis for steam line break and bank withdrawal from subcritical had assumed that three pumps were running. Westinghouse has again reviewed these accidents under the reduced flow conditions of one pump and has determined that for the rod ejection and steam line break events, the conclusions presented in the safety analysis will be unchanged. However, for the bank withdrawal from subcritical accident, the DNB design basis may not be met when only one pump is in operation.
It should be noted that the potential for bank withdrawal is present only when the reactor trip breakers are in a closed position. Furthermore, certain instrumentation features of the San Onofre Unit 1 reactor design will act to prevent an accidental rod withdrawal while the reactor is subcritical.
Currently, Westinghouse is evaluating the adequacy and reliability of these instrumentation features. If as the result of our continuing review of this 409OI 9 007 2DO W
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August 30, 1985 issue with Westinghouse, it is determined that more than one reactor coolant pump must be in operation in Mode 3 (reactor trip breakers closed), then a new Technical Specification change will be submitted for NRC approval.
As an interim measure, we have instituted new procedures that require operation of all three reactor coolant pumps in Mode 3 whenever the trip breakers are in a closed position. If the trip breakers are open, then operation in accordance with the existing Technical Specification 3.1.2.E is allowed.
If you have any questions, please call me.
Very truly yours, cc:
R. Dudley, NRC/NRR San Onofre Unit 1 Project Manager F. R. Huey, NRC Senior Resident Inspector, Units 1, 2 and 3