ML18038A711

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Special Rept:On 920813,DG Accelerated to Approximately 300 Rpm & Tripped on High Main & Connecting Rod Bearing Temperature. Caused by Clogged or Dirty Check Valve in Pneumatic Trip Sys.Valve Removed & Inspected
ML18038A711
Person / Time
Site: Nine Mile Point Constellation icon.png
Issue date: 09/14/1992
From: Carns N
NIAGARA MOHAWK POWER CORP.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NMP87248, NUDOCS 9209210155
Download: ML18038A711 (4)


Text

T NIAGA A kf MOHAWK NINE MILEPOINT NUCLEAR 8TATION/Po. BOX 32, LYCOMING, N.Y. 13093/TELEPHONE (315) 349-2447 Neil S. "Buzz" Cams Vice President September 14, 1992 Nuciear Generation NMP87248 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 RE: Docket No. 50-410 SPECIAL REPORT Gentlemen:

In accordance with Nine Mile Point Unit 2 (NMP2) Technical Specification 4.8.1.1.3, we are submitting the following Special Report concerning two (2) non-valid tests and non-valid failures of the Division I Standby Emergency Diesel Generator (2EGS "EG1).

SURVEILLANCE REQUIREMENTS Diesel Generator surveillance testing is normally performed on a monthly schedule (at least once per 31 days). This monthly testing interval is in conformance with NMP2 Technical Specification Table 4.8.1.1.2-1, Diesel Generator Test Schedule. There have been 0 failures in the last 20 starts and 3 valid failures in the last 100 valid tests in accordance with the test criteria set forth in Regulatory Guide 1.108.

EVENT DESCRIPTION The Division I Standby Emergency Diesel Generator (2EGS" EG1) was manually started in the test mode on August 13, 1992 at 2108 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.02094e-4 months <br />. The Diesel Generator accelerated to approximately 300 rpm and tripped on "High Main and Connecting Rod Bearing Temperature."

The main and connecting rod bearing temperature trip devices were inspected and all found in the non-tripped position.. This assured that there was rro bearing problem. As part of troubleshooting, the Diesel Generator was restarted a second time in the test mode on August 14, 1992 at 0212 hours0.00245 days <br />0.0589 hours <br />3.505291e-4 weeks <br />8.0666e-5 months <br />. The Diesel Generator again tripped on "High Main and Connecting Rod Bearing Temperature." The Diesel Generator was then subsequently started three times during troubleshooting and no trips were received.

ACTIONS TAKEN A Deviation Event Report (DER) ¹2-92-3233 was initiated to evaluate the Division I Standby Emergency Diesel Generator failed surveillance test trips and to determine the reportability requirements of the failed surveillances. Troubleshooting could not conclusively identify the reason for the trips. Therefore, the Diesel Generator start frequency has been increased to weekly from monthly, in an attempt to reproduce the anomaly. However, the trip could not be reproduced in the past six starts. We will evaluate the results of the weekly testing until we conclude that there is sufficient reliability to return to the normal monthly schedule 0 nP 9209210155 920914 PDR ADOCK 05000410 / old II 8 PDR 4/D

I Page 2 United States Nuclear Regulatory Commission September 14, 1992 CAUSE OF EVENT The most probable cause of the event is believed to be either a clogged or dirty check valve in the Pneumatic Trip System, which is bypassed in the emergency mode. The valve was removed and inspected/cleaned then reinstalled.

NON-VALID TEST NON-VALIDFAILURE DETERMINATION Per Technical Specification 4.8.1.1.3, and Regulatory Guide 1.108, Position C.2.e(2), the failed surveillance tests on Division I Standby Emergency Diesel Generator are not considered valid tests nor valid failures. The bases for the determination is that the spurious operation of a trip device caused the incident and this device is bypassed while in the emergency operating mode.

Very truly yours, Mr. N. S. Cams Vice President - Nuclear Generation NSC/AZP/Imc pc: Thomas T. Martin, Regional Administrator Region I Wayne L. Schmidt, Senior Resident Inspector