ML20097D412

Special Rept 96-01:on 960110,invalid Start Failure of DG B Occurred Due to Air Start Distributor Rotor Misalignment. New Shaft & Rotor Installed

ML20097D412
Person / Time
Site:	Callaway
Issue date:	02/01/1996
From:	Affolter R UNION ELECTRIC CO.
To:	NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
96-01, 96-1, ULNRC-3317, NUDOCS 9602120349
Download: ML20097D412 (4)

Text

Callaway Piant Pcat Offoce Box 620 ful ton. Mossoun 65251

(.bVION Etucruic

[43 February 1,1996 i

Document Control Desk Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop PI-137 Washington, DC 20555 ULNRC-3317 Gentlemen:

DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 FACILITY OPERATING LICENSE NPF-30 SPECIAL REPORT 96-01 INVALID START FAILURE OF DIESEL GENERATOR 'B' DUE TO AIR START DISTRIBUTOR ROT ^R MISALIGNMENT, This Special Report is submitted pursuant to Technical Specification (T/S) 4.8.1.1.3 and 6.9.2 concerning an invalid start failure of Diesel Generator 'B' due to air start distributor rotor misalignment.

R. D. Affolter Manager, Callaway Plant RDA/HDB/MAH/cmw Enclosure 1200@

9602120349 9.60201 gg4 'fl PDR ADOCK 05000483 l S PDR

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• ULNRC-3317 p February 1,1996 Page 2 cc: Mr. L. J. Callan Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 NRC Resident Inspector Ms. Kristine M. Thomas (2 copies)

Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 13-E-21 Washington, DC 20555 Manager, Electric Department Missouri Public Service Commission PO Box 360 Jefferson City, MO 65102 Mr. Thomas A. Baxter Shaw, Pittman, Potts, & Trowbridge 2300 N. Street N.W.

Washington, DC 20037 Mr. Steve Wideman (2 copies)

Supervisor, Licensing Wolf Creek Nuclear Operating Corporation P. O. Box 411 Burlington, KS 66839

, ./

s I i SPECIAL REPORT 96-01 INVALID START FAILURE OF DIESEL GENERATOR 'B' DUE TO AIR START DISTRIBUTOR ROTOR MISALIGNMENT At 0200 on 1/9/96 the 'B' Diesel Generator (D/G) was taken out of service and declared inoperable to perform routine maintenance. At 0053 on 1/10/96, during the performance of the maintenance, the 'B' D/G failed to start during an invalid test. The test was being l

conducted using only a portion of the air start system. The 'C' air starting train was used  !

in the test with 'D' train valved out. During normal operation, both 'C' and 'D' are aligned to the 'B' D/G.

Subsequent to the failure, Operators verified the starting air system lineup was correct per l l

procedure OSP-NE-00002, Standby Diesel Generator Periodic Tests and initiated a work request to begin troubleshooting. Further troubleshooting identified a problem in the 'C' i air start distributor. The distributor rotor had shined slightly on the 'C' train air start distributor shan. This resulted in air start timing for the 'C' train being retarded by approximately 15 degrees. This amount of retardation in conjunction with the position the engine had stopped after its last run kept the engine from starting. The root cause of rotor shining is attributed to the taperjoint between the rotor and the distributor shaft not being lapped at the factory during engine assembly. In addition, the torque applied to the nut holding the rotor on the distributor shan did not appear to be correct. This allowed the distributor shaft to slip in the rotor. A new shaft and rotor were installed. At 1240 on 1/11/96, D/G 'B' was successfully started on the 'C' train only. The D/G was declared operable per OSP-NE-00002 and Technical Specification (T/S) 4.8.1.1.2. The D/G was unavailable for a total of 58.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />.

Prior to the maintenance beginning on 1/9/96, the 'B' D/G was operable since its previous start because both 'C' and 'D' air start trains are normally lined up. D/G 'B' would have started with both air trains valved into the engine. Air start distributors ' A' and 'B' on ' A' D/G and 'D' on 'B' D/G will be checked in the next D/G outages of suflicient duration to ensure the timing of the rotors and the torque on the distributor shan rotor nuts are 7 .,

I correct. On 5/31/95, the 'B' D/G was started using only the 'D' air start train. On 12/27/95, the 'A' D/G was started using only the 'B' train of starting air. On 1/24/96, only the 'A' train was used to start the ' A' D/G. No problems were encountered with the air distributors during these single train starts.

'liis starting history of D/G 'B' as of this report date is summarized as follows:

No. of Valid Tests No. of Failures During No. of Failures During Valid Tests Invalid Tests 165 2* 5#

Last 20 0 1 Last 100 2 4  !

• LER 89-001-01, Special Report 93-05

1. Special Reports 85-05,89-01,89-08,90-02-01 Surveillance tests are currently performed at least once per 31 days for D/G 'B'. This is in conformance with T/S table 4.8-1 which requires a test interval of not more than 31 days if the number of failures in the last 20 valid tests is one or zero, or if the number of failures in the last 100 valid tests is four or less.