ML19294B520

LER 80-007/03L-0:on 800128,while Performing Surveillance Testing of HPCI Sys,Governor Valve Remained Shut After Turbine Was Shut Down W/Auxiliary Oil Pump Running.Caused by Actuator Sticking

ML19294B520
Person / Time
Site:	Vermont Yankee
Issue date:	02/27/1980
From:	Conway W VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19294B518	List: ML19294B517 ML19294B520
References
LER-80-007-03L, LER-80-7-3L, NUDOCS 8003040476
Download: ML19294B520 (2)

Text

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VTVYS1 05000271 LER 80-7/3L EVENT DESCRIPTION AND PROBABLE CONSEOUENCES While performing surveillance testing of the HPCI System, the governor valve remained shut after the turbine was shut down with the auxiliary oil pump running. This valve normally reopens when the remote turbine trip push button is released. Since the governor valve wculd not reopen, HPCI was declared inoperable and alternate surveillance testing began as re-quired by Tech. Spec. Section 3.5.E.2. The event was believed to be caused by either a shorted cable between the EGM control box and EGR actuator or sticking of the EGR actuator. The cable end at the ECM control box was found to have brittle insulation which may have caused the wires to short.

The damaged and was cut off and the cable was reterminated. At the same time, an investigation of the EGR actuator was underway. Before either of these actions were completed, the governor valve reopened. Termination of the EGM cable was completed and the EPCI System was restarted. This time, the system operated satisfactorily. The RPCI System was started three additional times (a total of four starts) with no failures. At this time, HPCI was declared operable and no further action was taken. Based on the above, the potential consequences to the health and saf ety of the public were mini =al. There have been no previous similar occurrences reported to the Commission.

CAUSE DESCRIPTION AND CORRECTIVE ACTION This event inicia .y appeared to be caused by either a shorted cable between the Woodward Et1 control box and EGR actuator or sticking of the EGR actuator. Upon investigation, the end of the cable at the control box was found to have brittle insulation but no evident signs of shorting.

The end of this cable was removed to prevent this cable from shorting in the future. The actuator was suspected of sticking but before it could be examined, the governor valve automatically opened. At that time, the actu-ator was manually operated several times and showed no signs of internal rust or sticking. This does not preclude the possibility that the actuator was stuck; however, the subsequent operation of the actuator has removed any substance that may have caused it to stick. The HPCI System was re-started four times af ter this event with no evidence of failure. This re-peated demonstration of operability precluded the need for additional cor-rective action and EPCI was returned to service.