ST-HL-AE-3929, Supplement to Special Rept:On 910710,spraying Lube Oil Leak Discovered at Cylinder 7R & Engine Manually Secured.Caused by Break in Exhaust rocker-to-inlet Rocker Crossover Lube Oil Line.Design of Lube Oil Line Changed

Supplement to Special Rept:On 910710,spraying Lube Oil Leak Discovered at Cylinder 7R & Engine Manually Secured.Caused by Break in Exhaust rocker-to-inlet Rocker Crossover Lube Oil Line.Design of Lube Oil Line Changed

ML20086S841
Person / Time
Site:	South Texas
Issue date:	12/19/1991
From:	Jump W HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ST-HL-AE-3929, NUDOCS 9201060026
Download: ML20086S841 (4)

Text

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The Light c o m p a n y S"' '3"*' I"3"' I'I""""u raGng st adon l'. o. Bus 289 wactn.onti.i nai77483 llouston Lighting & Pown 2 December 19, 1991 ST llL.AE 3929

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File No.: CO2 10CTR$0.36(c)(5)

U. S. Nuclear Regulatory Commission Attention: Document Control Desh Washington, DC 20555 South Texas Project Electric Generating Station Unit 2 Docket No. STN 50 499 Supplement to Special Repott Regarding Standby Diesel Generator 22 Valid Failure on July 10. 1991 i

Pursuant to the South Texas Project Electric Generatin6 Station

'lechnical Specificat ,ns 4.8.1.1.3 and 6.9.2, llouston Lighting & Power Company submits the attached supplement to the Speciel Report regarding the Standby Diesel Generator valid failure that occurred on July 10, 1991.

If you should have any questions on this matter, please contact Mr. C. A. Ayala at (512) 972 8628 or me at (512) 972 7921.

c$% (4m O Williarn J. Jum[ .

Manager, Nuclear Licensing PLW/1f

Attachment:

Supplement to Special Report Regarding Standby Diesel Generator 22 Valid Failure on July 10, 1991 I

300h0 nh SREP)91-316.001 9201000026 711219 A Subsidiar) of flouston industries incorporated /h/

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PDR ADOCU 05000499 S FDP e

Attachment ST lit. AE 3929 l Page 1 of 2 l l

South Texas Project Electric Generating Station $

Unit 2 Docket No. STN 50-499 i Supplement to Special Report Regarding Standby Diesel Generator 22 Valid Failure on July 10. 1991 i e

DESCit1PTION OF EVfjI:

on July 10, 1991, at approximately 1006 hours0.0116 days <br />0.279 hours <br />0.00166 weeks <br />3.82783e-4 months <br />, during a preparatory run of Standby Diesel Generatot 22 for engine analysis, a spraying lube oil Icak was  :

identified at cylinder 7R by the system engineer. The engine was manually  ;

secured at 1009 hours0.0117 days <br />0.28 hours <br />0.00167 weeks <br />3.839245e-4 months <br /> prior to engine loading. At 1013 hours0.0117 days <br />0.281 hours <br />0.00167 weeks <br />3.854465e-4 months <br />, SDG 22 was declared inoperable and the plant entered a Technical Specification 3.8.1.1. ,

LCO. Unit 2 was at 1006 power at the time of the event.

A york Request vas_ initiated to teplace the leaking exhaust rocker to inlet ,

rocker crossover lube oil line. The lube oil line was found to be completely i separated about 1/4 inch above the ferrule on the in.ct rocker side. A subsequent inspection of the exhaust rocker arm assembly found no abnormal conditions. An inspection of the inlet rocker area assembly found bushing wear (bronze) on the inlet rocker arm shaft and both iltters collapsed. The damage found on the inlet rocker assem54y was determiner ;o be a direct result of the lube oil line break and subsequent drop in lube oil flow.

On July 11, 1991, a new intake rocker, intake rocker arm shaft, exhaust crossover rocker arm, two lifters,-and a new 3/8 inch oil line were installed.

An operability run was performed following completion of the maintenance. On July 11, 1991, at approximately 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br />, SDG 22 was declared operable.

-CAUSES OF EVENT:

The-lube oil leak at cylinder 7R was caused by the break in the exhaust rocker to inlet rocker crossover lube oil itne. The lube oil line is a 3/8 inch 0 D., 0.035 inch wall thickness, type 304 stainless steel line. It was originally furnished with the engine. Examination results indicate the frac' 3 resulted from high cycle fatigue initiating from a localized region of / ..ing between the tube's outer surface and an assembly nut.

Misk.;nment of the tubing with an assembly nut resulted in the fretting condition.

ANALYSIS OF EVENT:

This SDG 22 start was performed to determine operability of SDG 22. The lube oil leak was discovered during a preparatory run. The engine was secured to protect it from significant damage. This event was classified as a valid failure.

SREPi91'310.001

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S Attachment  :

ST IIL AE-3929 Page 2 of 2 iou. ls 'fexe - ject Electric Generating Station s

Unit 2-Docket No. STN 50 499

. << ,-< -1 P' pert Regarding Standby Diesel Generator 22 g i ' a t'filure o- Ju.y 10 1991 22 c -

1. cs . nce wa. performed to replace the 3/8 inch 0.D.,

P 035 !. un '; .Sicknass, with 3/8-inch 0.D., 0.065-inch wall thickness,-

t3ge 716 - 4r teel tubing. Additional work included inspection for a}varent aw bde . the subsequent rep \accient of the inlet rocker arm, exhaust ctv4 Sever .ocker arm, inlet ,cker shaft, and two lifters. This work ei2 esapleted on July 11, 1991. The new tubing will have no impact on lubric3Jian capability.

- a, STPECS har notified tt,* cocper-Bessemer Owners Group of this event. l

3. An insptation for similar oil leaks and tubing configuration was performed on the othet cylinders in SDG 2' an/ 1 abnorm.il conditions were obs;rved. Similar inspections-have neen p,. 'ormed on the-other Ur.it 2=SDCs and th 'ait 1 SDCs with similar results.

4. The design of the exhaust rocker co inlet rocker lube oil line has'been I changed. The wall thickness of the lube oil line has been changed froa l 0.035 inch wall-thickness to 0.005 inch wall thickness. Replacement with l the thicker wal1<n tubing will be completed by the end of the next refueling outage for ecch unit.

l - 5. Verification will be performed following installation of tae thicker walled. tubing to ensure that the tubing and assembly nut are-in proper

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.alignmont.

iD,D. ITIONAL INFORMATIQti:

( There had been one valid failure in the preceding 20 valid tests of SDG 22

!~ 1he number of valid failures in the preceding 100 valid tests was-less than L four. Therefore, the testing frequency for SDG 22 temained at_once per 31 days l at the time of the failure.

L L A review of the work history found that on March 23, 1991, an exhaust rocker L to inlet rocker crossover lube oil line was disco sred cracked or. SDC 13 above L the fitting on the intake rockoc side. The line was replaced.

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• 1M 91-318.001

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ST HL AE- 3929

. :- - . Ilouston Lighting & Power Company File No. : CO2 f Sbuth Texas Project Electric Generating Station Page 2

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Regional Administrator, Region IV Rufus S. Scott Nuclear Regulatory Commission Associare General Counsel 611 Ryan Plaza Drive, Suite 400 Houston Lighting & Power Company Arlington, TY. 76011 P. O. Box 61867 Houston, TX 77208 ,

George Dick. . Project Manager

'U.S. Nucicar Regulatory ~ Commission INPO Washington, DC- 20555 Records Center 1100. Circle 75 Parkway J. I. Tapia Atlanca, CA 30339-3064

- Senior Resident Inspector c/o U. S. Nuclear Regulatory Dr. Joseph M. Hendrio-Commission 50 Be11 port Lane

-P. O. Box 910 Bellport, NY 11713 Bay City TX 77414 D. K. Lacker J.-R. Newman, Esquire Bureau of Radiation Control Newman 6'holtzinger, P.C. Texas Department of Health 1615 L Street, N.W. 1100 West 49th Street

-Washington, DC 20036 Austin, TX 78756-3189 D. E. Ward /T. M. Puckett Central 1 Power and Light-Company _

P, 0 : Box 2121-Corpus Christi: TX 78403

.J..C. Lanier/M. B. Lee City of Austin Electric Utility Department P.O. Box 1088 Austin, TX 78/67 K.' J. Fiedler/M. T. Hardt City Public Service Board-P. 0,. Box 1771-San. Antonio,'TX 7F '

i Revised 10/11/91 L4/NRC/_

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