ML13308B458
| ML13308B458 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/01/1977 |
| From: | Head J SOUTHERN CALIFORNIA EDISON CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 8103050976 | |
| Download: ML13308B458 (2) | |
Text
Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE J. T. HEAD, JR.
ROSEMEAD, CALIFORNIA 9i770 TE VICE PRESIDENT July 1, 1977 23 572A472 U. S. Nuclear Regulatory Commission Region V Office of Inspection and Enforcement Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Docket No. 50-206 San Onofre Unit No. 1 Attention: R. H. Engelken, Director
Dear Sir:
This letter describes a reportable occurrence involving the Uninterruptible Power Source (UPS). The UPS is the preferred source of 480 volt power to MOV 850C, the safety injection discharge valve for reactor coolant system loop C. Submittal is in accordance with the reporting requirements stipulated in Section 6.9.2 of the Technical Specifications.
At 1625 hours0.0188 days <br />0.451 hours <br />0.00269 weeks <br />6.183125e-4 months <br /> on June 14, 1977, an alarm was received in the Unit 1 Control Room indicating a failure of the UPS inverter. The local alarm on the inverter indicated the DC fuse was open. The power source for MOV 850C was transferred to the alternate 480 volt source, motor control center number three.
A subsequent investigation revealed that a capacitor in a capacitor bank contained in the commutating circuit had failed. The failure of this capacitor precipitated failure of an additional capacitor in another capacitor bank, also in the commutating circuit. Capacitor failure was evidenced by swelling and rupture of the case. It is postulated that capacitor electrical leakage became excessive causing internal heating, expansion and ultimately rupture of the casing.
All capacitors in the affected capacitor banks and the failed fuse were replaced. At 2355 hours0.0273 days <br />0.654 hours <br />0.00389 weeks <br />8.960775e-4 months <br /> on June 14, 1977, the inverter was returned to service.
The power source for MOV 850C was transferred back to its preferred source.
If you should require additional information concerning this occurrence, please contact me.
Sincerely,.
Attachment:
Licensee Event Report 77-08 cc:
Office of Inspection & Enforcement (30)
Office of Management Information & Program Control (3)
U-6 0 5-0 9 70.
Southern California Edison Company P. 0. BOX 800 2244 WALNU T GROVE AVENUE J. T. HEAD, JR.
ROSEMEAD, CALORN!A. 9i77 TELE P H ONE
-E1ETJuly.
1, 1977 235 7 2-147 2 U. S. Nuclear Regulatory Commission t
Region V Office of Inspection and Enforcement Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Docket No. 50-206 San Onofre Unit No. 1 Attention: R. H. Engelken, Director
Dear Sir:
This letter describes a reportable occurrence involving the Uninterruptible Power Source (UPS). The UPS is the preferred source of 480 volt power to MOV 850C, the safety injection discharge valve for reactor coolant system loop C. Submittal is in accordance with the reporting requirements stipulated in Section 6.9.2 of the Technical Specifications.
At 1625 hours0.0188 days <br />0.451 hours <br />0.00269 weeks <br />6.183125e-4 months <br /> on June 14, 1977, an alarm was received in the Unit 1 Control Room indicating a failure of the UPS inverter. The 'local alarm on the inverter indicated the DC fuse was open. The power source for MOV 850C was transferred to the alternate 480 volt source, motor control center number three.
A subsequent investigation revealed that a capacitor in a capacitor bank contained in the commutating circuit had failed. The failure of this capacitor precipitated failure of an additional capacitor in another capacitor bank, also in the commutating circuit. Capacitor failure was evidenced by swelling and rupture of the case. It is postulated that capacitor electrical leakage became excessive causing internal heating, expansion and ultimately rupture of the casing.
All capacitors in the affected capacitor banks and the failed fuse were replaced. At 2355 hours0.0273 days <br />0.654 hours <br />0.00389 weeks <br />8.960775e-4 months <br /> on June 14, 1977, the inverter was returned to service.
The power source for MOV 850C was transferred back to its preferred source.
If you should require additional information concerning this occurrence, please contact me.
Sincerely,
Attachment:
Licensee Event Report 77-08 cc:
Office of Inspection & Enforcement (30)
Office of Management Information & Program Control (3)
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