ML20085N156

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Special Rept:On 911009,invalid Failure of Diesel Generator 1A Occurred & Generator Unavailable for 24 H.Possibly Caused by Stuck Fuel Racks.Fuel Rack Cleaning Will Be Changed from Semiannual to 4 Month Cleaning Cycle
ML20085N156
Person / Time
Site: Catawba Duke Energy icon.png
Issue date: 11/06/1991
From: Tuckman M
DUKE POWER CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9111140155
Download: ML20085N156 (3)


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DUKEPOWER November 6,1991 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

Subject:

Catawba Nuclear Station, Unit 1 Docket No. 50-413 Special Report l

Invalid Failure of Diosel Generator 1A l

Pursuant to Technical Specification 4.8.1.1.3 and 6.9.2, find attached a Special Report concerning the Unit 1 Diesel Generator A (D/G 1A) luvalid failure that occurred on October 9,1991.

Very truly yours,

. b.

M. S. Tuckman CRL/ DG1 A110.91 Attachment xc: S. D. Ebneter Regional Administrator, Region 11 W. T. Orders l

Senior Resident Inspector R. E. Martin, ONRR i

I 9111140155.911106 PDR ADOCK 050004$.3

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w SPECI AL REPORT CATAWBA NUCLEAR STATION

-DIESEL GENERATOR 1A INVALID FAILURE DURING MONTIILY OPERABILITY TESTING OF ENGINE An invalid failure-(start # 913) of Diesel Generator (D/G) 1A occurred on October 9,1991 during the Maintenance run following routine scheduled preventative maintenance. D/G 1A was on a monthly operability test schedule at the time of this invalid failure. There have been 0 valid failures in the past 20 valid starts and 0 valid failures in the past 100 valid starts for D/G 1 A. D/G

'1A was unavailable for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as a result of this invalid failure. D/G 1A

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remains on a monthly operability test schedule por Technical Specification 4.8.1'.1.2 Table 4.8-1.

The diesel' generator was out of service in a " diesel day" status to perform routine Instrumentation'and Electrical (IAE) preventative maintenance (PM) activities.

With the PM activities complete, a post-maintenanco start was attempted. Th" engine rolled on air but it did not start and the " Unit Failure to Start" annunciator alarmed. A work request (5G4500PS) was generated to investigate the cause of the failure.

IAE, Maintenance, Operations and Maintenance Engineering Support (MES) technical support talked with the operr. tors to collect aP. the first hand

-observations and try t.o determine why the D/G did not start. Preliminary observations and checks were made by IAE, but no specific item e+ood out. The fuel racks were dirty, but did not seem so dlety that they coulci positively be identified as the cause of failure.

Diesel Generator 1B's fuel racks were examined and found to be satisfactory.

A' test start was conducted to help determine the cause of the failure. Personnel were placed at strategic locations to cbserve the start. The identical procedural' steps v.are conducted in the start -preparation, as well as the start, in an -

attempt to recreate the same start conditions. The diesel generator startect in a normal time frame of 6.3 seconds. -It continued to run through the group II shutdowns. All temperatures and pressures (pneumatic and-hydraulic) were normal. The diesel generator was shutdown.

IAE inspected and tested all the pneumatics to see if a problem would show up that could have prevented a start. No improper operations were discovered.

The fuel racks were left dirty while IAE performed their inspections. In an effort to re-create the failure, the diesel generator was not rescheduled to start until the next day.- This was to allow time for the engine components to set.

Approximately 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> after the last start, personnel were placed at strategic locations to observe another D/G test start. The original steps that resulted in the failure were repeated exactly. The diesel generator started normally and ran with no hesitation. The diesel generator was again shut down.

Eirho fuel racks were cleaned and the bearings lubricated per the routine PM.

This PM had been 1 reviously completed on 4/22/91. The next due date for this PM was 10/23/91. The PM work request was in Planning being scheduled at the time of this event..

The visicorder on the generator control panel has inputs for fuel rack position indication, llowever,. the inputs had not been set up on the Unit I diesel generators. This indication would have provided the fuel rack positions. This information could have specifically pointed to the fuel racks as the problem and The greatly reduced the time to restore the diesel generator to service.

necessary paperwork has been completed and the visicorder is now set up to indicate fuel rack position during every start up.

The work request paperwork was completed and the Operability Test was conducted on the 1 A diesel generator with satisfactory results. The 1A diesel generator was declared operable.

p Although it can not be proven concretely, it is believed that this _dlesel generator failure was caused by stuck fuel racks.

Because of the general condition of the fuel racks, the predefined work requests

- associated with the cleaning will be changed from a semi-annual cleaning cycle to a 4M (4 month) cleaning cycle. The fuel racks general condition will be monitored to validate the effectiveness of the revised frequency.

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