ML13308B442
| ML13308B442 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/10/1978 |
| From: | Head J SOUTHERN CALIFORNIA EDISON CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 8103050900 | |
| Download: ML13308B442 (2) | |
Text
lifornia Edison Compan
.4 VS P.O0. BOX 800),a 2244 WALNUT GROVE AVENUE J.T. HEAD, JR.
ROSEMEAD, CALIFORNIA 91770 ELEPHONE VICE PRESIDENT
'4 1F5721472 February 10, 1978 U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region V Walnut Creek Plaza, Suite 202 1990 North California Boulevard Walnut Creek, California 94596 Attention: R. H. Engelken, Director Docket No. 50-206 San Onofre Unit 1
Dear Sir:
This letter describes a reportable occurrence involving the Salt Water Cooling System. Submittal is in accordance with the reporting requirements stipulated in Section 6.9.2.b of Appendix A to Provisional Operating License DPR-13.
On January 16, 1978, while the south salt water cooling pump was in operation, routine maintenance was planned for the north pump. In accordance with Technical Specification 3.3.1.C, the auxiliary salt water pump was started and the south pump placed in standby to demonstrate availability of the redundant component (auxiliary pump) prior to removing the north pump from service. With the auxiliary pump in operation, the north pump was removed from service and cleared for main tenance.
At 1010, the operator made the decision to restart the south salt water pump and place the auxiliary pump in standby. When the south pump was restarted, the motor breaker tripped open, accompanied by a 480V overcurrent trip alarm. Since maintenance on the north pump had not yet commenced, it was returned to service and placed in operation at 1035. The auxiliary pump, which had remained in opera tion during this interval, was placed on standby once the north pump was restarted.
After removing the south pump from service and clearing it for maintenance, the pump motor and leads were meggered and found to have normal resistance to ground.
The normal motor breaker was removed, a spare breaker installed and the circuit satisfactorily tested. The south salt water pump was then placed in operation so that maintenance -could continue on the north pump.
Inspection of the normal motor breaker revealed that the problem was due to a faulty internal overload relay caused by a leaking diaphragm. The faulty relay has since been replaced and the normal south pump breaker returned to service.
There was no degradation of plant safety during this incident. Plant opera tion, with one operable salt water cooling pump, is permitted for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> by Technical Specification 3.3.1.B.(6).
Should you require additional information concerning this incident, please contact me.
Sincerely
Attachment:
Licensee Event Report 78-001 cc:
Director, Office of Inspection & Enforcement Director, Office of Management Information & Program Control