ML20062P094

Final Deficiency Rept Re Failure of Colt-Pielstick Diesel Generator Thrust Bearing.Initially Reported on 800513. Crankshaft Thrust Bearings Replaced.Also Reportable Per Part 21

ML20062P094
Person / Time
Site:	Wolf Creek
Issue date:	08/16/1982
From:	Koester G KANSAS GAS & ELECTRIC CO.
To:	Seidle W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
REF-PT21-82 10CFR-050.55E, 10CFR-50.55E, KMLNRC-82-237, NUDOCS 8208240069
Download: ML20062P094 (6)

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KANSAS GAS AND ELECTRIC COMPANY Tef E LE CTMC COP /P ANY GLENN L MOE9TER WICE Pet S DG N f hvCL & A4 August 16, 1982 Mr. W.C. Seidle, Chief  ;.

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Reactor Projects Branch 2  !  !-

U.S . Nuclear Regulatory Commission ' !\' . AUG I 91982 Region IV  !

LUg) 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 KMLNRC 82-237 Re: Docket No. STN 50-482 Subj: Final 10CFR50.55(e) Report Diesel Generator Thrust Bearing

Dear Mr. Seidle :

Attached is the final report submitted pursuant to 10CFR50.55(e) regarding failure of a diesel generator thrust bearing. Colt Industries filed a Part 21 Report on this subject in May of 1980 and Kansas Gas and Electric Company advised Region IV on May 13, 1980, that the Wolf Creek diesel generator thrust bearings would have to be replaced. The bearing replacement has now been completed.

If you require additional information, please contact me or Mr. Otto Maynard of my staff.

Yours very truly, f/h $

GLK:bb Attach cc: Mr. Thomas Vandel, w/a Resident NRC Inspector P.O. Box 311 Burlington , Kansas 66839 8%06440069 3 201 N. Market - Wichota. Kansas - Mail Address: PO Box 208 i Wichita. Kansas 67201 - Telephone: Area Code (316) 261-6451

10CFR50.55 (e ) FINAL REPORT cn DIESEL GENERATOR THRUST BEARING FAILURE For WOLF CREEK GENERATING STATION, UNIT NO. 1 Kansas Gas and Electric Company Wichita, Kansas August 16 , 1982

TABLE OF CONTENTS

1. Introduction

2. Description of Deficiency

3. Analysis of Safety Implications

4. Corrective Actions

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I. Introduction During shop tests of the Number 4 Colt-Pielstick Type PC-2 diesel generator se t , the crankshaft thrust bearing failed. Colt Industries submitted a Part 21 report and notified affected utilities of the problem.

The failed unit had been built for Wolf Creek Generating Station and was the same type as the one unit already delivered to the site. A " hold shipment" was imposed on the failed unit and a Deficiency Report was initiated for the unit already delivered to Wolf Creek. An investigation into the cause of failure was then initiated so that required corrective action could be determined.

II. Description of Deficiency he thrust bearing in question consists of two 180 degree units which fit together in the housing to form a 360 degree bearing around the shaft.

We investigation revealed that the gap between the bearing halves was not sufficient to allow for the circumferential thermal growth of the bearing from assembly conditions (shop temperature) to operating conditions (140 degrees F). Once the bearing halves contacted each other, the thermal growth was then forced radially outwards in the bearing causing the bearing to come in contact with the bearing housing. Based on the worst case dimensional conditions, the restricted growth caused the bearing to bow in the housing which resulted in interference with the rotating crankshaft collar. This interference then generated additional heat, which caused further thermal growth, eventually causing the bearing to fail.

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III. Ancly3io o_f,Stfaty f Implicationa W diesel generator is required to operate under certain postulated accident conditions. Failure of the diesel generator crankshaf t thrust bearing would result in failure of the diesel generator. herefore, since this failure could adversely affect the safe operation of the plant, this matter is reportable under the requirements of 10CFR50.55(e) .

IV. Q)rrective Action he manufacturer's recommended corrective action was to machine the upper half bearing st the gap surface an alditional .015/.020 inches which would increase the gap to .060/.080 inches. mis would permit expansion of the bearing without contact between the halves.

Kansas Gas and Electric Cbmpany (KG&E) and the Architect / Engineer found this corrective action to be acceptable. However, during a tour of the Cbit facilities it was discovered that Qalt had two thrust bearings they used interchangeably. One, used in the Wolf Creek generators, was an English design and the other available bearing was a German design. h primary difference was in the configuration of the oil slots.

After a thorough review of this matter, KG&E decided to replace the English designed bearing with the German bearing and machine the upper half an additional .015/.020 inches as recommended by the manuf acturer.

%e switch to the German bearing was made because KG&E felt the German bearing was a better design and would provide better service . However, i i

the primary corrective action taken to preclude bearing f ailure was the I machining of the upper half bearing to increase the gap.

'1he crankshaft thrust bearings on the Wolf Creek diesel generators have now been replaced with the above mentioned German bearing with the upper half machined to provide the required clearance.

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