ML13324A799
| ML13324A799 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 01/21/1986 |
| From: | Medford M Southern California Edison Co |
| To: | Lear G Office of Nuclear Reactor Regulation |
| References | |
| TASK-2.K.3.05, TASK-TM NUDOCS 8601270109 | |
| Download: ML13324A799 (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 January 21, 1986 Director, Office of Nuclear Reactor Regulation Attention: G. E. Lear, Director PWR Project Directorate No. 1 U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 TMI Action Item II.K.3.5, "Automatic Trip of Reactor Coolant Pumps" San Onofre Nuclear Generating Station Unit 1
Reference:
Letter, M. 0. Medford, SCE, to 3. A. Zwolinski, NRC, TMI Action Item II.K.3.5, "Automatic Trip of Reactor Coolant Pumps,"
October 10, 1985 The referenced letter provided SCE's response to the subject post-TMI requirement for San Onofre Unit 1. The resolution called for our use of subcooled margin as the reactor coolant pump (RCP) trip criterion for San Onofre Unit 1. The response addressed those items identified in NRC Generic Letter Nos.83-10d and 85-12, with the exception of the information concerning the reliability of the instrumentation used to determine the RCP trip setpoint and the RCP trip components. Accordingly, the following information is provided to resolve these two remaining items and to complete SCE's response to the subject post-TMI requirement.
Instrumentation Reliability As stated in the referenced letter, the subcooled margin monitor (SMM) that was installed in response to the post-TMI inadequate core cooling requirements will be used to establish the RCP trip setpoint.
As this instrumentation was designed and qualified to be functional in anticipated post-accident conditions, it is considered to be of the highest reliability for instrumentation of this type.
Trip/Restart Components Reliability The initial trip of the RCP's is due to the trip and coastdown of their power source, the main turbine generator. Therefore, it is not necessary to evaluate the reliability of this system. The components used for 8601270109 860121 PDR ADOCK 05000206 PDR AD -
J. Knight (1tr only)
EB (BALLARD)
EICSB (ROSA)
PSB (GAMMILL)
RSB (BERLINGER)
FOB (BENAROYA)
Mr. G.
January 21, 1986 RCP restart and subsequent trip do not require an evaluation for reasons stated below (i.e., acceptable plant response to a small break loss of coolant accident (SBLOCA) is not dependent on tripping the RCP's).
Therefore, an evaluation of the reliability of these components is not necessary.
It is noted that the report enclosed with the referenced letter indicated an acceptable plant response to a SBLOCA regardless of RCP status.
Therefore, the reliability of the RCP trip components and of the instrumentation used to determine the RCP trip setpoint is not as important for San Onofre Unit 1 as it might be for other PWR's which require RCP trip to assure an acceptable plant response to certain SBLOCA's.
Based upon the above discussion, it is concluded that the RCP trip/restart and use of the SMM are adequate for their current application.
If you have any questions regarding the above discussed information, please let me know.
Very truly yours,