ML13324A891
| ML13324A891 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/19/1986 |
| From: | Medford M Southern California Edison Co |
| To: | Lear G Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8606230188 | |
| Download: ML13324A891 (1) | |
Text
Southem California Edison Company P. 0 BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 M. 0. MEDFORD TELEPHONE MANAGER. NUCLEAR LICENSING (818) 302-1749 June 19, 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 Auxiliary Transformer Tap Settings Optimization San Onofre Nuclear Generating Station Unit 1
Reference:
Letter, M. 0. Medford, SCE, to 3. A. Zwolinski, NRC, dated December 4, 1985 The referenced letter provided the results of the voltage monitoring program which evaluated the transformer tap settings selected as a result of the Auxiliary Tap Setting Optimization Study dated November 13, 1984.
Based upon the results of the voltage monitoring program, it was determined that administrative controls were necessary to avoid undesirable 480V bus loading during operation in Modes 1 through 3. Additional administrative controls during Modes 5 and 6 operation were also determined to be necessary to maintain the desirable 480V bus voltage.
Further refinement of the supporting calculation to the Auxiliary Tap Setting Optimization Study incorporating a detailed study of the saltwater cooling pump starting characteristics has resulted in deletion of the administrative controls on the 480V bus loading for Modes 1 through 3 operation. The revised calculation indicates that even in the unlikely case where the minimum starting voltage for the saltwater cooling pumps is less than the desired minimum of 80% of rated motor voltage, the pumps will start upon demand. Based upon these results, SCE has determined that the administrative controls on the 480V bus loading for Modes 1 through 3 operation are unnecessary and will be deleted.
The administrative controls for Modes 5 or 6 operation will be maintained in accordance with the referenced letter.
If you have any questions or comments, please do not hesitate to contact me.
Very truly yours, 8606230189 860619 PDR ADOCK 05000206 P
PDR cc:
F. R. Huey, Senior Resident Inspector, Unit 1, 2 and 3 0\\O0