ST-HL-AE-3834, Special Rept:On 910710,spraying Lube Oil Leak Identified at Cylinder 7R & Standby Diesel Generator Declared Inoperable. Caused by Break in Exhaust Rocker to Inlet Rocker Crossover Lube Oil Line.Wall Thickness Tubing Replaced

Special Rept:On 910710,spraying Lube Oil Leak Identified at Cylinder 7R & Standby Diesel Generator Declared Inoperable. Caused by Break in Exhaust Rocker to Inlet Rocker Crossover Lube Oil Line.Wall Thickness Tubing Replaced

ML20077M316
Person / Time
Site:	South Texas
Issue date:	08/09/1991
From:	Kinsey W HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ST-HL-AE-3834, NUDOCS 9108130296
Download: ML20077M316 (4)

Text

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/,u p r t 5, 1991 ST ilL AE 3834 File No.: CO2 10CFR50.36(c)(L)

U. S. Nuc1 car ReBulatory Comrnission Attention: Docurnent Control Desk Washington, DC 20555 South Texas Project Electric Generating Station Unit 2 Docket No STN 50 499 Special Report Regarding Standby Diesel Generator 22 Valid Failure on July 10. 1991 Pursuant to the South Texas Project Electric Generating Station Technical Specifications 4.8.1.1.3 and 6.9.2, llouston Lighting 6 Power Company subtnits the attached Special Report regarding the Standby Diesel Generator valid failure that occurred on July 10, 1991. A supplemental report addressing subsequent findings will be submitted by December 31, 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.

i W.11. Kinsey Vice President, Nuclear Generation PLW/ amp

Attachment:

Special Report Regarding Standby Diesel Generator 22 Valid Failure on July 10, 1991 9100130296 910809 FW ADOCK O':.000499 .I 5 PDR q}

5 e 81-20L 001 A Subsidiai> of flouston Industries Inanporaied /aIV v g\

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ST HL-AE- 3834 llouston Lighting & Power Con.pany File No.: GO?

Page 2 South Texas Project Electric Generating Station cc:

Regional Administrater, Region IV Rufus S. Scott Nuclear Regulatory Commission Associate General Counsel 611 Ryan Plaza Drive, Suite 1000 Houston Lighting & Power Company Arlington, TX /C011 P. O. Box 61867 Houston, TX 77208 Ceorge Dick, Project Manager U.S. Nuclear Regulatory Commission INPO Vashington, DC 20555 Records Center 1100 circle 75 Parkway J. 1. Tapia Atlanta, CA 30339-3064 Senior Resident Inspector c/o U. S. Nuclear Regulatory Dr. Joseph M. Hendric Consission 50 Bellport Lane P. O. Box 910 Be11 port, NT 11713 Bay City, TX 77414 D. K Lacker J. R. Newman, r. squire Bureau of Radiction Control Newman & Holtzinger, P.C. Texas Department of Health 1615 L Street, N W. 1100 West 49th Street Washington DC 20036 Acc.in, TX 78756-3189 D. E. Ward /T M. Puckett Central Power and Light company P. O. Sox 2121 Corpus Christi, TX 78403 J. C. Lanier/M. B. Lee City of Austin Elcetric Utility Department P.O. Box 1088 j Austin, TX 78767 K. R. Fiedler/M T. Hardt City Public Service Board P. O. Box 1771 San Antonio, TX 78296 i

I Revised 07/09/91 i l

L4/NRC/

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t Attachment ST HL-AE-3834 Page 1 of 2 South Texas Project Electric Generating Station Unit 2 Docket No. STN 50-499 Special Report Regarding Standby Diesel Generator 22 Valid Failure on_2ulv 10. 1991 DESCRIPTION OF EVENT:

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 Generator 22 for engine analysis, a spraying lube oil leak 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.

LGO. Unit 2 was at 100% power at the time of the event.

A Work Request was initiated to replace the leaking exhaust rocker to inlet rocker crossover lube oil line. The lube oil line was found to be completely separated about 1/4-inch above the ferrule on the inlet rocker side. A subsequent inspection of the exhause rocker arm assembly found no abnormal conditions. An inspection of the li.iet rocker arm assembly found bushing wear (bronze) on the inlet rocker arm shaft and both lifters ;ollapsed. The damage found on the inlet rocker assembly was determined to be a direct result of the lube oil line break and subsequent drop in lube oil frov.

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.

GAUSES OF EVENT:

The lube oil leak at cylinder 7R was caused by the break in the exhaust rocker to inlet rocker crossover lube oil line. 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. The replacement tubing at STPEGS bas normally been 3/8-inch 0.D., 0.065-inch wall thickness, type 316 staiqless steel. The cause of the tube break is not known at this time. Additional actions are planned to evaluate the cause(s) of the tube break.

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.

SREP\91-207.001

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l Attachment  !

ST-HL+ AE 3834 Page'2 of 2 q l

South Texas Project Electric Generating Station Unit 2  :

. Docket No. STN $0 499 Special Report Regarding Standby Diesel Generator 22 ,

Valid Failure on July 10. 1991 1

CORRECTIVE ACTIONS: .i

1. Corrective maintenance was performed to replace the 3/8 inch 0.D. ,

0.035 inch wall thickness, with 3/8-inch 0.D., 0.065 inch wall thickness, type 316 stainlass steel tubing. Additional work included inspection for apparent damage and the subsequent replacement of the inlet rocker arm, ,

exhaust crossover rocker arm, inlet rocker shaft, and two lifters. This +

work was completed on Jtly 11, 1991. The new tubing will have no' impact t on lubrication capability.  ;

2. STPEGS has notified the Cooper-Bessemer Owners Group of this event and requested them to determine if any similar events have occurred at member stations in addition to Palo Verde (discussed under " Additional  :

It. formation") . *

3. An inspection of the configuration of the tubing and for oil leaks on the other cylinders in SDG 22 has been performed. Similar inspections will ,

be performed on the other Unit 2 SDCs and the Unit 1 SDCs. A supplemental report indicating the results of these inspections will be submitted by December 31, 1991.

4. A metallurgical analysis of _the tubing is being performed by HL&P. The results will be evaluated and further actions determined. This will be-addressed in the follow-up report to be submitted by December 31, 1991.

ADDITIONAL INFORMATION:

There has been one valid failure in the last 20 valid tests of SDC 22. The number of valid failures in the last-100 valid tests is'less than four.

Therefore, the testing frequency for SDG 22 remains once per 31 days.

A' review of the work history found that on March 23, 1991, an exhaust rocker to. inlet rocker crossover lube oil line was discovered cracked on SDG 13 above the fitting on the intake rocker side. The line'was replaced.

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. SREPn 91 207. 001 i

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