05000206/LER-1979-001, Forwards LER 79-001/03L-0

Forwards LER 79-001/03L-0

ML13333A121
Person / Time
Site:	San Onofre
Issue date:	02/06/1979
From:	Head J SOUTHERN CALIFORNIA EDISON CO.
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML13333A122	List: 05000206/LER-1979-001, Forwards LER 79-001/03L-0 05000206/LER-1979-001-03, /03L-0 on 790109:during Normal Operations,While Testing Containment Isolation Valves,Isolation Valve on Cooling Water from Containment Air Handling Units Failed to Close.Exact Cause Undetermined
References
NUDOCS 7902130111
Download: ML13333A121 (4)

LER-1979-001, Forwards LER 79-001/03L-0

Event date:
Report date:
2061979001R00 - NRC Website

text

February 6, 1979 U. S. Nuclear Regulatory Comrmission Region V Office of Inspection and Enforcement Suite 202, Walnut Creek Plaza 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-515, a containment isolation valve on the cooling water return line from the sphere air handling units.

Submittal is in accordance witlh the reporting require ments stipulated in section 6.9.2(b) of Appendix A to the Provisional Opera ting License DPR-13.

At 12:30 p.m. on January 9, 1979, CV-515 failed to close during contain ment isolation valve testing.

This valve, an Efcomatic electrohydraulic valve, opens by operation of a motor driven hydraulic oil pump and closes by de-ener gization of two solenoids which trip a latching mechanism, allowing the valve to close via a compressed spring.

The valve closed after the removal.of fuses supplying motor and control power to the valve.

Following valve closure, the valve also failed to fully reopen.

An examination of the valve revealed that a hydraulic oil leak. had pre vented the valve from opening due to lack of sufficient fluid.

No cause could be determined, however, for the initial failure of the valve to close.

The hydraulic leak was repaired, the tripping mechanian lubricated, and the valve successfully stroked several times.

The containment isolation valve test was also repeated successfully. The valve was returned to service that same day.

Since the cooling water to the containment air handling units is a closed system inside the containment, the failure of this valve did not represent a violation of containment integrity.

In addition, intermittent operation of this valve is not required following a postulated accident.

790213 1/!

- 2 A similar incident occurred at San Onofre Unit 1 in January of 1978.

This previous failure was reported via LER-78-002. Due to these two failures, an engineering evaluation of Efcomatic valve operators will be performed with the objective of identifying potential failure modes and implementing corres ponding corrective actions. In addition, during the next refueling outage all Efcomatic operators installed at Unit 1 will be inspected for possible defects and repaired as necessary.

Should there be any further questions regarding this matt er, please contact me.

Sincerely, (J. T. Head)

GTM/dl9a

Attachment:

Licensee Event Report 79-001 cc:

Director, Office of Inspection and Enforcement (30)

Director. Office of Management Information and Program Control (3) bcc:

IIRC Members OSRC Members E. J. Bresnahan C. R. Kocher/J. A. Beoletto D. E. Nunn D. R. Pigott (Chickering & Gregory)

J. C. Sorensen G. T. McLandrich EDM Files

Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 91770 J.

T.

HEAD, JR.

TELEPHONE VICE PRESIDENT 213-572-1472 February 6, 1979 U. S. Nuclear Regulatory Commission A

Region V Office of Inspection and Enforcement Suite 202, Walnut Creek Plaza 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-515, a containment isolation valve on the cooling water return line from the sphere air handling units. Submittal is in accordance with the reporting require ments stipulated in section 6.9.2(b) of Appendix A to the Provisional Opera ting License DPR-13.

At 12:30 p.m. on January 9, 1979, CV-515 failed to close during contain ment isolation valve testing. This valve, an Efcomatic electrohydraulic valve, opens by operation of a motor driven hydraulic oil pump and closes by de-ener gization of two solenoids which trip a latching mechanism, allowing the valve to close viaa compressed spring. The valve closed after the removal of fuses supplying motor and control power to the valve. Following valve closure, the valve also failed to fully reopen.

An examination of the valve revealed that a hydraulic oil leak had pre vented the valve from opening due to lack of sufficient fluid. No cause could be determined, however, for the initial failure of the valve to close. The hydraulic leak was repaired, the tripping mechanism lubricated, and the valve successfully stroked several times. The containment isolation valve test was also repeated successfully. The valve was returned to service that same day.

Since the cooling water to the containment air handling units is a closed system inside the containment, the failure of this valve did not represent a violation of containment integrity. In addition, intermittent operation of this valve is not required following a postulated accident.

- 2 A similar incident occurred at San Onofre Unit 1 in January of 1978.

This previous failure was reported via LER-78-002. Due to these two failures, an engineering evaluation of Efcomatic valve operators will be performed with the objective of identifying potential failure modes and implementing corres ponding corrective actions. In addition, during the next refueling outage all Efcomatic operators installed at Unit 1 will be inspected for possible defects and repaired as necessary.

Should there be any further questions regarding this matter, please contact me.

Sincerely, Attachment: Licensee Event Report 79-001 cc: Director, Office of Inspection and Enforcement (30)

Director, Office of Management Information and Program Control (3)