ML19248D217

LER 79-010/01T-1 on 790416:notifies of Potential for Failure of Inside Recirculation Spray Pump Motors.Caused by Reduction of Internal Clearance Due to Heat Gradient as Motor Comes Up to Operating Temp.Mods Made to Clearance

ML19248D217
Person / Time
Site:	Beaver Valley
Issue date:	08/01/1979
From:	Werling J DUQUESNE LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19248D204	List: ML19248D203 ML19248D208 ML19248D209 ML19248D217 ML19248D221 ML19248D224 ML19248D226
References
LER-79-010-01T, LER-79-10-1T, NUDOCS 7908130434
Download: ML19248D217 (2)

Text

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 1012 l lCeneral Flectric Company hw notifico Be,vor V,1 1 ov Pnure 9tnrfnn nf nnronri,1 l o 3 jfor failure of the Inside Recirculation Sor'av Pumn motors. As a restilt of numn 1 o 4 l testing at another facility, it has been determined that the motor thrust bearines I o s l cay seize or bind af ter several hours of running time. The motors are 480 volt, l o r, l300 horsepower, 1800 rpm mot'rs o with Model No. SK6319XJ20A. l o 7 l 0 H l l 7 8 9 60 SYSTEM CAUSE CAUS E C O'3 P VAtyt CODE CODE SUBCODf COMPONE NT CODC SU3CODC suuCOCE 7

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.4 CAUSE DESCRIPTION AND CORRECTIVE AC TIONS h i o l Analysis of the failure mode indicates the problem may occur when all part I i i l tolerances of the bearing and bearing housing are at the extreme end of the j

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Attachment To LER 79-10/0lT-1 Beaver Valley Power Station Duquesne Light Company Docket No. 50-334 General Electric Company has notified Beaver Valley Power Station of a potential for failure of the Inside Recirculation Spray Pump motors. As a result of pump testing at another facility, it has been determined that the motor thrust bearings may seize or bind after several hours of running time.

Analysis of the failure mode indicates the problem may occur when all bearing part tolerances are at the extreme end of the spectrum. The problem is caused in those cases by a reduction of internal clearances caused by the heat gradient as the motor comes up to operating temperature.

In order to eliminate the potential for failure, a modification has been completed to increase internal clearances. This modification involves replacing the lower thrust hearing with a loose internal fit bearing, increasing the size of the bearing housing to allow greater clearance between the bearing outside diameter and the housing inside diameter, and installing a new design lower slinger. The pump motors were reinstalled and satisf actorily tested and returned to service. .

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