ML13322A710
| ML13322A710 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/14/1980 |
| From: | Baskin K Southern California Edison Co |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8002200589 | |
| Download: ML13322A710 (2) | |
Text
Southern California Edison Company P. 0.
BOX 800 2244 WALNUT GROVE AVENUE
- ROSEMEAD, CALIFORNIA 91770 K. P. BASKIN TELEPHONE MANAGER, NUCLEAR ENGINEERING (213) 572-1401 AND LICENSING February 14, 1980 Director, Office of Nuclear Reactor Regulation Attention:
D. L. Ziemann, Chief Operating Reactors Branch #2 Division of Operating Reactors U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Monitoring of Control Rod Position San Onofre Nuclear Generating Station Unit 1 In accordance with your letter dated November 5, 1979, we indicated by letter dated January 4, 1980 that a request for license amendment revising our technical specifications was expected to be provided by February 15, 1980 to limit control rod misalignment to a +12.5 inch margin allowance. As a result of the effort to develop a technical specification which implements the appropriate misalignment requirements based on the Westinghouse Standard Technical Specifications, it has become apparent that the previously determined margin allowance of +12.5 inches is insufficient to allow for instrumentation drift due to system temperature transients during periods of startup and load change.
In order to prevent misalignment indications in excess of the technical speci fication allowance, Westinghouse is in the process of developing a basis to be used as a justification of a margin allowance of +15 inches as is used in the 12 foot core Westinghouse reactors.
In addition, a statistical evaluation of past operating history will be performed, with regard to instrument drift of the rod position indication system, in order to determine whether instrumen tation drift results in rod position indications which would not be covered by the increased margin allowance. If this is the case, it may be necessary to justify by analysis an increased margin over and above the proposed +15 inches.
800220-0
-2 Due to the extent of the additional work required, it is expected that a license amendment revising the technical specifications to limit control rod misalignment will be submitted by March 31, 1980.
Also, if the results of the statistical evaluation of instrument drift indicate that additional analysis is required, we will advise you of this eventuality and of the need for additional time to perform these analyses.
If you have any questions or desire additional information, please contact me.
Very truly yours,