ULNRC-03066, Special Rept:On 940809,discovered Two Invalid a Failures During Troubleshooting Due to Air Start Solenoid Failures

Special Rept:On 940809,discovered Two Invalid a Failures During Troubleshooting Due to Air Start Solenoid Failures

ML20072T071
Person / Time
Site:	Callaway
Issue date:	09/08/1994
From:	Blosser J UNION ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
ULNRC-03066, ULNRC-3066, NUDOCS 9409150052
Download: ML20072T071 (5)

Text

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Union Etncrnic September 8,1994 23 U. S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 ULNRC-03066 Gentlemen:

DOCKET NUhlBER 50-483 CALLAWAY PLANT UNIT 1 FACILITY OPERATING LICENSE NPF-30 SPECIAL REPORT 94-04 l INVALID DIESEL GENERATOR 'A' FAILURES DURING TROUBLESIIOOTING DUE TO AIR START SOLENOID FAILURE l

This Special Report is submitted pursuant to Technical Specification (T/S) 4.8.1.1.3

and 6.9.2 concerning two invalid failures of Diesel Generator 'A' due to an air start solenoid failure during troubleshooting.

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J. D. Blosser Manager, Callaway Plant JDB/HDB/MKD/Irj Enclosure cc: Distribution attached 1 otin o n a~vvv0 9409150052 94o908 gDR ADOCK 05000483 [h 1' pnn ljj

cc distribution for ULNRC-03066 hir. J. B. hiartin Regional Administrator U. S. Nuclear Regulatory Commission Region ill 801 Warrenville Road l Lisle, Illinois 60532-4351 hir. L. Raynard Wharton (2 copies)

Licensing Project hianager U. S. Nuclear Regulatory Commission OWFN - hiail Stop 13E21 Washington, D. C. 20555 l

hianager, Electric Department l

hiissouri Public Service Commission P. O. Box 360 Jefferson City, h10 65102 Records Center Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, GA 30339 l

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

, hir. hi. J. Farber l Chief, Reactor FrojectsSection III A U. S. Nuclear Regulatory Commission l Region III 801 Warrenville Road l Lisle, Illinois 60532-4351 l

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hir. Thomas A. Baxter Shaw, Pittman, Potts & Trowbridge 2300 N. Street N.W.

Washington, D.C. 20037 NRC Senior Resident Inspector i

SPECIAL ILEPOltT 94-04 INVALID DIESEL GENEllATOlt 'A' FAILURES DULLING TROUBI ESIIGOTING DUE TO AIR STAllT SOLENOID FAILURE On 8/9/94, KJPV0001B, Diesel Generator (D/G) 'A' Starting Air Supply Pressere Control Valve, was replaced to correct an air leak. At i109 CDT on 8/10/94, D/G 'A' successfully started and ran per procedure OSP-NE-00002, Standby Diesel Generator Periodic Tests. During this post-maintenance start, the 'A' starting air tank pressure dropped 60 psi and the 'B' tank pressure dropped 7 psi. This indicated that the newly installed solenoid valve may not have opened. In order to troubleshoot, the 'A' train of the starting air was valved out at 1549 on 8/10/94, and D/G starts were attempted using only the 'B' train of starting air. At 1602 and 1613, D/G 'A' failed to start.

At 1800, the 'A' train of starting air was returned to service. At 1936, D/G 'A' was ,

successfully started using only the 'A' train of starting air, verifying operability of the D/G. The solenoid valve was replaced on 8/l1/94. The D/G was successfully started using only the 'B' train starting air at 1000 on 8/11/94.

On 8/11/94, when the suspect solenoid valve was being rebuilt in the maintenance shop, a guide pin misalignment was identified. This condition caused KJPV0001B to fail to open.

A review of the initial valve replacement revealed that, in order to reterminate the valve solenoid assembly, the electricians had been required to partially disassemble it from the valve body. Unlike other solenoid operated valves at the plant, this type contains a guide pin integral to the coil assembly which fits into a spring loaded armature assembly. During reinstallation of the solenoid, the guide pin was misaligned. Misalignment of the guide pin with the armature results in the armature holding the valve in the closed position. The non-standard nature of the solenoid assembly, along with the confined working space in the field, resulted in failure to recognize the misalignment when the electricians reassembled the valve.

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f This' event will be discussed with utility maintenance personnel to clarify work practices on non-standard solenoid valves. Work instructions will be revised to provide specific guidance for future solenoid valve replacements.

D/G 'A' was operable at all times except when the ' A' starting air train was isolated to allow troubleshooting on the 'B' starting air solenoid valve. This was a pre-planned evolution of short duration.

Regulatory Position C.2.e(7) of Regulatory Guide 1.108, Revision 1, August 1977, states: " Tests performed in the process of troubleshooting should not be considered -

valid tests." Therefore, because the diesel failed to start during troubleshooting on the

'B' train of the air start system, these were invalid failures.

A starting history of D/G 'A' 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 182 7*@ 10 #

• Special Reports 84-02, 87-10, 89-03, 91-02, 92-01 and 94-01; LER 87-002-00

@ Four failures in the last 100 tests. One failure in the last 20 valid tests.

1. Special Reports 85-01, 85-02, 85-07. 86-01, 89-02, 89-07 & 90-01.

Surveillance tests are currently performed at least once per 31 days for D/G 'A'. 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.

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