ML20100M520

Provides EDG Annual Rept for 1995

ML20100M520
Person / Time
Site:	San Onofre
Issue date:	02/29/1996
From:	Marsh W SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-84-15, NUDOCS 9603050388
Download: ML20100M520 (2)

Text

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' 60VIIIIliN CAIOIUI6l4

?j ' EDISON An tul50N IN1LR%41l OVAL Gnnpung February 29, 1996' U. S. Nuclear Regulatory Commission Document' Control Desk Washington, D. C. 20555

Subject:

' Docket Nos. 50-361'and 50-362 Diesel Generator Annual Report - 1995 San Onofre Nuclear Generating Station, Units 2 and.3.

The purpose of this letter is to provide the Emergency Diesel Generator i Annual Report for 1995. This report is required by Technical Specifications 4.8.1.1.3 and 6.9.1 of Facility Licenses NPF-10 and NPF-15 for Units 2 and 3 respectively. The enclosure includes the information requested in Regulatory Position C.3.b of Regulatory Guide +

(RG) 1.108, as revised _ by Generic Letter (GL) 84-15, for the one valid test failure that occurred in'1995.

If you require any additional information, please let me know.

Sincerely, I

t y e Walter C. Marsh (

Manager of Nuclear Regulatory Affairs Enclosure cc: L. J. Callan, Regional Administrator, NRC Region IV J. E. Dyer, Director, Division of Reactor Projects, NRC Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV '

M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3 J. A. Sloan, NRC Senior Resident Inspector, Units 2 and 3 Institute of Nuclear Power Operations (INPO) i n e n n O tt F  !

9603050388 960229  !

PDR ADOCK 05000361 R PDR .;

P O. Ikn 128 -

San Clemente. CA 92674-0128 -

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Emergency Diesel Generator Report Southern California Edison Company San Onofre Nuclear Generating Station Units 2 and 3, Docket Nos. 50-361 and 50-362

' Introduction The following information is provided in accordance with Technical Specification Surveillance Requirement 4.8.1.1.3 and Regulatory Position C.3.b. of Regulatory Guide (RG) 1.108 as revised by Generic Letter (GL) 84-15. RG 1.108 requested information on seven items for each valid or invalid test failure.

Event Date: November 15, 1995

1. - This event was a valid failure of the San Onofre Unit 3 Emergency Diesel Generator (EDG) 3G002.

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2. This was the fourth failure in the last 100 valid tests.

3. . The failure was caused by the improper time out of an agastat time i delay relay. Relay K3, which blocks the low-low oil pressure trip during engine starts, timed out early unblocking the trip before oil pressure increased above the trip setpoint. The trip was unblocked 9 seconds after the EDG start signal vice the normal 50 seconds.

A root cause evaluation determined the most likely cause was a l misadjusted set screw, set by the manufacturer, that prevented proper  ;

latching of the relay. This misadjustment caused the set screw to  !

touch a plastic surface on the movable contact assembly during relay i operation. This unintended contact limited the travel of the contact ,

and caused wearing of the plastic component. Over time, particles l worn from the plastic surface accumulated on the tip of the set screw j further reducing the travel distance of the contact. This slow reduction in contact travel eventually affected the timing of the l relay. The failed relay had been in service since April 1988.

4. The failed relay was replaced and tested. A satisfactory surveillance was performed on EDG following the repairs. The corresponding relays in the other EDGs were tested satisfactorily. A review of the San ,

Onofre Maintenance Management System (SOMMS) and the NPRDS databases, did not identify any similar failures. The vendor was also unaware of i any similar failures. Therefore, this is considered a random failure. '

5.

The EDG was unavailable for 12.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> as a result of this failure. [

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6. EDG 3G002 was in a 31 day testing mode during this time period.

7. The surveillance test interval was in accordance with the schedule of l Technical Specification Table 4.8-1.

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