ML20235Q044

Forwards Investigation Rept FAL-00024, Emergency Diesel Generator Floating Bushing Failure & Metallurgical Svcs Rept FAL-00050

ML20235Q044
Person / Time
Site:	North Anna
Issue date:	09/30/1987
From:	Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20235Q047	List: ML20235Q044 ML20235Q055 ML20235Q066
References
86-179F, NUDOCS 8710070474
Download: ML20235Q044 (2)

Text

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VINGINIA' ELECTRIC AND PowsH COMPANY )

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September 30, 1987 l

United States Nuclear Regulatory Commission Serial No. 86-179F Attention:-Document Control Desk NAPS /JHL Washington, D. C. 20555 Docket Nos. 50-338 50-339 License Nos. NPF-4 i NPF-7 Gentlemen:

VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNIT NOS. 1 AND 2 3 EMERGENCY DIESEL GENERATOR INVESTIGATION REPORT l During the inspection of the IH emergency diesel generator (EDG) in March 1987, we identified a problem involving extrusion of the piston pin floating bushings for two upper' pistons. This finding was documented in our letter dated March 31, 1987, Serial No. 86-179C. In our' letter dated April 16, 1987, Serial No. 86-179E, we informed you that an examination program had been developed for one piston pin and two floating bushings that were removed from the IH EDG. Attachment 1 provides the examination report that was prepared by 1 the Virginia Electric and Power Company Failure Analysis ~ Laboratory. Please  !

i note that 'the report indicates that the piston pin floating bushing in the number 9 upper piston insert was undamaged. It was undamaged in the sense that it was in the initial stages of failure. It was slightly extruded but still acceptable. The bushing was removed from the EDG to compare it to the piston pin floating bushing in the number 12 pisten insert.

Also, in our letter dated April 16, 1987, we informed you that an engine inspection program would be conducted during the Unit I refueling outage. We committed to discuss any significant findings as a result of this inspection.

Attachment 2 provides this information and also provides the information requested by NRC Inspection Report 87-15, dated June 29, 1987.

It is concluded that the bushing extrusion resulted from inadequate lubrication, engine overload, or a combination of both. It is important to note that both the 1H and 1J EDGs were operated for several months using the previous engine lubricant prior to our change-out to the new Chevron DELO 6000 oil in April, 1986. In addition, surveillance test requirements for this unit included fast, cold starts and more frequent testing until Technical Specification Amendment 83 was approved by the NRC on August 22, 1986.

Further, we recently discovered that the IJ emergency diesel generator power ,

output meter was out of calibration by 8% (low). The meter has now been I calibrated. These conditions may have contributed to the bushing extrusion observed in Unit 1.

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EDG 2H in Unit 2 was recently examined during the current refueling outage after having operated for one complete fuel cycle. No bushing degradation was observed .

We conclude, therefore, that the actions we have taken as discussed in our March 31, 1987 letter have been effective in assuring the reliability of North Anna's diesel generators.

1 If you have any questions, please contact me.

Very truly yours, i

W.L.kewart 4 dank 4 Attachment cc: U. S. Nuclear Regulatory Commission 101 Marrieta Street, N. W.

Suite 2900 Atlanta, Georgia 30323 Mr. J. L. Caldwell NRC Senior Resident Inspector North Anna Power Station I

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