ML13308B440
| ML13308B440 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/23/1978 |
| From: | Head J SOUTHERN CALIFORNIA EDISON CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 8103050886 | |
| Download: ML13308B440 (2) | |
Text
SouthernT OR DOET FILE COY Southern California Edison Company P o. BOX OO 2244 WALNUT GROVE AVENUE J. T. HEAD, JR.
ROSEMEAD, CALIFORNIA 91770 TELEPHONE VICE PRESIDENT 213-572-1472 February 23, 1978 U. S. Nuclear Regulatory Commission Region V Office of Inspection & Enforcement Walnut Creek Plaza, Suite 202 1990 North California Boulevard Walnut Creek, CA 94596 Attention: Mr. R. H. Engelken, Director Docket No. 50-206 San Onofre Unit 1
Dear Sir:
This letter describes a reportable occurrence involving CV-517, one of two Containment Spray Flow Control Valves. Submittal is in accordance with the reporting requirements stipulated in Section 6.9.2.b of Appendix A to Provisional Operating License DPR-13.
At 2230 on January 30, 1978, CV-517 was opened but subsequently failed to close during a quarterly inservice operational test. The valve, an electro-hydraulic valve, opened properly by operation of the hydraulic oil pump. Closure of the valve occurs by de-energizing two solenoids which trip a latch bar, allowing the valve to close by actuation of a compressed spring. In this case, the latch bar failed to withdraw upon solenoid de-energization. The latch bar was manually tripped and the valve operated properly tothe closed position. It was immediately verified that redundant Containment Spray Flow Control Valve CV-518 could be opened and closed remotely.
CV-517 and CV-518 are installed in parallel and one valve is required to open during the initial phase of safety injection to provide the required spray flow.
These valves provide a parallel path around a fixed orifice. During the recircula tion mode of safety injection both valves are closed. This reduces spray flow to an amount permitted by the fixed orifice such that only one of the two recircula tion pumps would be sufficient to supply the required amount of recirculation flow through the charging pumps and the required amount of spray flow through the refueling water pumps.
Since CV-518 was verified operable, the operator elected to remove the DC power from CV-517, thereby insuring that it would remain closed until repairs could be accomplished.
Subsequently, the operating mechanism of CV-517 was inspected for any obvious defects. None were found. The solenoid operated latching mechanism was thoroughly lubricated and the valve was test operated satisfactorily. Until recently, CV-517 was infrequently operated. With the quarterly valve testing program initiated this year, the valve will receive more frequent operation which should cause it to be less susceptible to problems as described in this letter.
Should you require additional information concerning this incident, please contact me.
Sincerely,
Attachment:
Licensee Event Report 78-002 cc: Director, Office of Inspection & Enforcement Director, Office of Management Information & Program Control