ST-HL-AE-3032, Special Rept:On 890226,nonvalid Failure of Standby Diesel Generator 13 Occurred.Probably Caused by Sticking Test Mode Fuel Control Valve.Valve to Be Replaced on 890522

Special Rept:On 890226,nonvalid Failure of Standby Diesel Generator 13 Occurred.Probably Caused by Sticking Test Mode Fuel Control Valve.Valve to Be Replaced on 890522

ML20247K460
Person / Time
Site:	South Texas
Issue date:	03/27/1989
From:	Vaughn G HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ST-HL-AE-3032, NUDOCS 8904050252
Download: ML20247K460 (4)

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The Light company P.O. Bo< 1700 Houston, Texas 77001 (713) 228 9211 Ilouston Lighting & Power March 27, 1989 ST-HL-AE-3032 File No.: G02 10CFR50.36(c)(5)

U. S. Nuclear Regulatory Commission Attention: Do:ument Control Desk Washington, DC 20555 South Texas Project Electric Generating Station Unit 1 Docket No. STN 50-498 Special Report Regarding A Nonvalid Failure of #13 Standby Diesel Generator on February 26, 1989 Pursuant to the South Texas Project Electric Generating Station Technical Specifications 4.8.1.1.3 and 6.9.2, Houston Lighting & Power submits the attached Special Report regarding a nonvalid failure of the #13 Standby Diesel Generator on February 26, 1989.

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

G.E. b y G. E. Vaughn Vice President h j Nuclear Operations GEV/BEM/n1

Attachment:

Special Report Regarding A Nonvalid Failure of #13 Standby Diesel Generator on February 26, 1989 l

l 890405025gg3))${9g ADOC PDR PDC n S

NL.89.075.01 A Subsidiary of Ilouston Industries Incorporated Q-t 4

r v-flouston 1.ighting & Power Company ST-HL-AE-3032 File No.: G02 Page 2 CCS

'1 Regional Administrator, Region IV Rufus S. Scott Nuclear Regulatory Commission Associate General Counsel ,

611 Ryan Plaza Drive, Suite 1000 Houston Lighting & Power Company l Arlington, TX 76011 P. O. Box 1700 Houston, TX 77001 George Dick, Project Manager U. S. Nuclear Regulatory Commission INFO Washington, DC 20555 Records Center 1100 Circle 75 Parkway Jack E. Bess Atlanta, Gs. 30339-3064 j Senior Resident Inspector-Unit I c/o U. S. Nuclear Regulatory Commission Dr. Joseph M. Hendrie .

P. O. Box 910 50 Be11 port Lane 0 Bay City, TX 77414 Be11 port, NY 11713 1 1 l

J. I. Tapia Senior Resident Inspector-Unit 2 c/o U. S. Nuclear Regulatory Commission P. O. Box 910 Bay City, TX 77414 J. R. Newman, Esquire l Newman & Holtzinger, P.C.

l 1615 L Street, N.W.

Washington, DC 20036 R. L. Range /R. P. Verret  !

Central Power & Light Company P. O. Box 2121 l l

Corpus Christi, TX 78403 j l

R. John Miner (2 copies)

Chief Operating Officer l i

City of Austin Electric Utility l 721 Barton Springs Road l Austin, TX 78704 j R. J. Costello/M. T. Hardt City Public Service Board P. O. Box 1771 San Antonio, TX 78296 I

Revised 12/21/88 )

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Ilouston Lighting & Power Company Attachment ST-HL-AE-3032 Page 1 of 2 l

South Texas Project Electric Generating Station Unit 1- i Decket No. STN 50-498 '

Special Report Regarding A Nonvalid j Failure of #13 Standby Diesel Generator on February 26, 1989 j i

1 DESCRIPTION OF EVENT:

On February 26, 1989, Unit I was in Mode 5 at 0% Reactor Power. At 0439 hours0.00508 days <br />0.122 hours <br />7.258598e-4 weeks <br />1.670395e-4 months <br /> s Standby Diesel Generator (SDG) #13 was started for surveillance testing. It i attained rated speed and voltage within ten seconds as required. Less than j one minute later it tripped when released from the " emergency mode". No i alarms were present which would have indicated an emergency mode trip.

Troubleshooting was performed to identify the cause of the trip. Since the

" Master Trip Circuit" light was on at the local control panel', the trip was determined to have been caused by the non-emergency mode shutdown circuit. In the emergency mode non-emergency trips are bypassed. Operations personnel 3 conducted checks on engine systems and verified that.there were no abnormal l conditions present which could have caused the trip. The engine was started again at 0445 hours0.00515 days <br />0.124 hours <br />7.357804e-4 weeks <br />1.693225e-4 months <br /> on February 26, 1989 for further troubleshooting. The SDG j started normally and did not trip when released frcm the " emergency mode". j The SDG was secured after a five (5) minute unloeded run. The SDG was started  !

again at 0517 hours0.00598 days <br />0.144 hours <br />8.54828e-4 weeks <br />1.967185e-4 months <br /> and the surveillance testing was successfully performed.

There have been two previous non-valid failures of SDG 13 which had no obvious cause. As a result of these failures three valves in the control air system were replaced in an attempt to prevent recurrence. These threa valves belong to a group of four valves whose misoperation could result in the symptoms l observed during this event. The remaining " Test Mode Fuel Control Valve" has l not been replaced since this group of non-valid failures began to occur. A review of non-valid failures on other SDG's identified that a similar valve was the source of a previous trip on SDG 12. All of the non-valid failures on SDG 13 to date have occurred on the first attempt to release the SDG from the

" emergency mode". Subsequent transfers have been successful. Therefore, it is believed that the " Test Mode Fuel Control Valve" mt be sticking and frees up after the initial attempt to transfer the SDG to th : " Emergency Mode".

NL.89.075.01

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Il6uiton 1.ighting & Power Company ,

1 Attachment I ST-HL-AE-3032 j Page 2 of 2 CAUSE OF OCCURRFNCE:

The most probable cause of this nonvalid failure is sticking of the " Test Mode i Fuel Control Valve".

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ANALYSIS OF EVENT:

This event occurred as a result of a trip which is bypassed in the emergency mode. Per the criteria in Regulatory Guide 1.108, this event has been classified as a non-valid failure. In the event of an actual challenge of the SDG, it would have performed its safety function without tripping.

t CORRECTIVE ACTION:

The " Test Mode Fuel Control Valve" will be replaced during the next' train l outage which is currently scheduled for May 22, 1989. I ADDITIONAL INFORMATION:  !

Per the criteria of Regulatory Guide 1.108, the failure described in this report has been classified as a nonvalid failure. As such, the test interval for SDG 13 remains at 31 days. There have been 31 valid tests performed on SDG 13 since receipt of the Unit 1 Operating License. There have been no valid failures.

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