ML20129A401

Special Rept 85-006:on 850601,during Periodic Surveillance Testing of Diesel Generator A,Generator Secured Prematurely Due to Erratic Low Jacket Water Pressure Indication & Alarm. Caused by Use of Valve Lineup to Test Starting Air Sys

ML20129A401
Person / Time
Site:	Wolf Creek
Issue date:	06/28/1985
From:	Koester G KANSAS GAS & ELECTRIC CO.
To:	Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
85-006, 85-6, KMLNRC-85-165, NUDOCS 8507150289
Download: ML20129A401 (3)

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• KANSAS GAS AND ELECTRIC COMPANY THE ELECTAC COMPANY OLENN L MOESTER vH:t reas DENT - NUCLEAR June 28, 1985 Mr. R.D. Martin, Regional Administrator U.S. Riclear Regulatory Comission fT 7:

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Region IV ~- ~'y' I 611 Ryan Plaza Drive, Suite 1000 ', . , , ,

Arlington, Texas 76011 '- 'I ICCi KMURC 85-165 j Re: Docket No. STN 50-482 Subj: Special Report 85-006 ar Mr. Martin:

_ne enclosed Special Report is submitted pirsuant to Technical Specifications 6.9.2 and 4.8.1.1.3.

If you have any questions concerning this matter, please contact me or Mr. Otto Maynard of my staff.

Yours very truly, kWN Glenn L. Koester

/#t-Vice President - R1 clear Gm: dab Enclosure xc: PO'Connor (2), w/a JCumins, w/a 8507150289 850628 PDR ADOCK 05000482 s PDR-b g&CEE IO

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l 201 N. Market - WicMta, Kansas - Mail Address: PO. Box 208 I Wichsta. Kansas 67201 - Telechone: Area Code (316) 2616451

., q a Special Report 85-006 Diesel Generator Invalid Failure On June 1, 1985, at approximately 0407 CDP, the periodic surveillance testing required by Technical Specifications was commenced on diesel generator (D/G) "A" utilizing the surveillance procedure STS KJ-005A,

" Manual / Auto Start, Synchronization and Loading of Energency Diesel Generator NE01." D/G "A" was started, and subsequently secured prematurely at approximately 0413 cur due to an erratic low jacket water pre sure indication aM alarm.

It has been determined that the low jacket water pressure iMication and alarm was due to the valve lineup being utilized to test the starting air system of the diesel generator.

We diesel has two reduMant 100 percent capacity starting air systems.

During each monthly surveillance test of the diesel, one starting air system is isolated aM th7 other is tested to ensure its operability on a staggered basis. After the diesel has been started, the other startire air system is returned to service, and left in that configuration for normal diesel lineup. Previous experience has revealed that openirg the second starting air isolation valve allows air to enter the header very rapidly, which causes the excessive flow check valves in the sensor lines to shut, resulting in flow oscillations in the lines and giving rise to erroneous alarms and fluctuating pressure indications from the indicators fed by these sensing lines. A Temporary Modification had been developed to allow for the existing bypass valves around the excessive flow check valves to be opened one-quarter turn during engine testing, thus preventing these oscillating flow coMitions ard erroneous alarms. In this particular instance, the Temporary Modification was ineffective in dampening these flow oscillations, aM reverse flow through the check valves lowered the instrument air pressure which caused the erroneous indication and alarm. We reverse flow was due to the pressure differentials in the lines created by the testirg lineup. We Temporary Modification did not contribute to the existence of the reverse flow conditions.

Once this was determined to be the cause of the problem, D/G "A" was restarted at approximately 0450 CDP, loaded successfully, aM secured at approximately 0603 CDP. D/G "A" was subsequently realigned for automatic operation, thus cunpleting a valid successful test of D/G "A".

D/G "B" was operable throughout this time period. D/G "A" was unavailable for service for 30 minutes while an investigation into the cause of the low pressure indication was being performed.

In order to prevent flow oscillations when the second air starting system is valved in, an alternate method for determining the operability of each starting air system is being developed, aM will be incorporated into the surveillance procedures STS KJ-005A and STS KJ-005B (for D/G "B"). Instead of isolating one starting air system prior to ergine start and then valvirg it back in af ter the engine has started, the operability of both starting air systems will be verified simultanecasly by observirg the pressure decrease in the air tanks when the solenoid valves for the starting air system open on an ergine start signal.

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mis event has been classified as an invalid failure per the criteria provided in Regulatory Position C.2.e(2) of Regulatory Guide 1.108. The start of D/G "A" at 0407 CDP on June 1,1985, was terminated prematurely due to erroneous irdications frm instrments that perform no control or protection function in the opwation of the diesel generator unit.

Were have been nine (9) valid successful tests of D/G "A" since the empletion of preoperational teating on D/G "A", including the successful test mentioned in this report. During this same time period, including tne invalid failure discussed in this report, seven (7) invalid failures and no valid failures have occurred on D/G "A". Were have been eight (8) valid successful tests on D/G "B" since the completion of preoperational testing on D/G "B". Durityj the same time period, four (4) invalid failures and no valid failures have occurred on D/G "B".

Wis event had no impact on the diesel generator surveillance testing frequency of at least once per 31 days. Wis' is in conformance with the specifications of Regulatory Position C.2.d(l) of Regulatory Guide 1.108 and Technical Specification Table 4.8-1 which require the test interval to be not more than 31 days if the number of valid failures in the last 100 tests is one or zero.

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