ML19247A594

First Interim Deficiency Rept:When Diesel Generator at Operating Temp & Retarted Between 15 Minutes & 3-h After Shutdown,Damage to Turbocharger Thrust Bearing May Occur.Caused by Oil Sys Not Receiving Lubrication

ML19247A594
Person / Time
Site:	Sequoyah
Issue date:	07/20/1979
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML19247A587	List: ML19247A586 ML19247A594
References
NCR-MEB-79-26, NUDOCS 7908010408
Download: ML19247A594 (1)

Text

e E:, CLOSURE SLQUUY.W NUCLEAR PLAST UNITS 1 AND 2 DIESEL GENERATOR TURLOCHARGER LULRICATIU:.

NCR MES 19-26 10 CFR 50.55(e)

FIRST INTERIM RLFORT Description of Deficiency This deficiency was reported by the diesel manufacturer, Electro-Gotive Division (EMD) of General Motors, to TVA's contractor for the emergency diesel generators, Power Systems a division of Morris-Knudsen. Power Systems subsequently reported this deficiency to TVA. This deficiency was also reported to the NRC, which issued IE circular No. 79-12. The deficiency occurs when the diesel generator has been operated long enough for the lube oil to reach operating temperature, shutdown, then restarted between 15 minutes and 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. During this period, if a restart is attempted, damage to the diesel engine turbocharger thrust bearing may occur. This could lead to failure of the turbocharger and the emergency diesel generator.

The cause of this deficiency appears to be related to the "soakoack" pump which is designed to supply lubrication to the turbocnarger bearings during standby conditions and to keep the accessory lubricating oil system primed to support a fast start. Following operation of the diesel generator the viscosity of the lubricating oil is such that the accessory lubricating oil sy stem does not receive any oil, therefore cepeated restarts during the period of 15 minutes to 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> following a hot shutdown of the diesel generator can cause engine damabe due to lack of prime oil syster, pressure. Occasional instances of restart during these periods are inconse-quential. However, repeated unneccessary restarts for purposes of testing or machinery exercise during the period of 15 minutes to 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> after shutdown needlessly accelerates wear and detracts from total engine life.

TVA considers this deficiency reportable because it could lead to reduced reliability and availability of the emergency onsite power source wnich is required to ensure that the plant can reach and naintain a safe snut-down under all conditions.

Corrective Actions Other IVA plants that have EMD diesel engine driven generators incluce Hartsville, Phipps Bend, Wat ts Ear, and Browns Ferry. These other nuclear plants are presently being investigated to determine enethet or not tney are affected by this deficiency The operating staff at Sequoyah has been cautioned not to start the dieser senerators unneccessarily between 15 minutes and 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> following shutdown from a previous run in which the engine has reached full operating temperature. Additional corrective actions are being investigated oj E10 ,

Power Systems, and TVA. These corrective actions will be deta 1ec in a subsequent report on this deficiency.

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