ML20097K069

Special Rept 84-02:on 840812,diesel Generator a NE01 Failed During Surveillance Test.Caused by Main Feeder Breaker NB-01-11 Failing to Close Due to Mechanical Binding of Manual Closing Switch.Closing Switch Reset

ML20097K069
Person / Time
Site:	Callaway
Issue date:	09/11/1984
From:	Miltenberger S UNION ELECTRIC CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
84-02, 84-2, ULNRC-922, NUDOCS 8409240192
Download: ML20097K069 (3)

Text

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1-UNION EtscTaic COMPANY CALLAWAY PLANT September 11, 1984 "^7" ,.o^ x .",'o" FULTON, MO. 85259 James G. Keppler Regional Administrator USNRC Region III Office 799 koosevelt Road Glen Ellyn, Illinois 60137 ULNRC-922 DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 SPECIAL REPORT 84-02 DIESEL GENERATOR VALID FAILURE

Dear Mr. Keppler:

, The enclosed Special Report is submitted pursuant to Technical Specifications 4.8.1.1.3 and 6.9.2 concerning the valid failure of a diesel generator, j

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S. E. Miltenberger Manager, Callaway Plant AW

)hWHS/WRR/JWK/drs Enclosure cc: Distribution attached O 483 PDR

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ccc distribution for ULNRC-922

' James G.'Keppler USNRC Region III'0ffice f 799 Roosevelt Road

_ Glen Ellyn, IL 60137 American Nuclear. Insurers c/o Dottie Sherman,. Library -

The' Exchange Suite 245 '

270 Farmington. Avenue

'Farmirgton, CT 06032

.b Records Center Institute of Nuclear Power Operations -

Suite 1500 1100 Circle 75 Parkway Atlanta, GA 30339 NRC Resident Inspector Missouri Public-Service Commission .

D. F. Schnell J. F. McLaughlin J. E. Davis (Z40SR)

D. W. Capone-F. D. Field R. L. Powers A. C. Passwater/D. E. Shafer/D. J. Walker G. A. Hughes W. R.. Robinson (QA Record)

W. H. Stahl R. H. Leuther A. P. Neuhalfen -

R. A. McAleenan L. K. Robertson (470)(NSRB)

Merlin Williams,' Wolf Creek SEM Chrono 3456-0021.C Z40ULNRC

- G56.37 N. Date

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SPECIAL REPORT 84-02' DIESEL GENERATOR' VALID FAILURE on 8/12/64 at 1120 CDT while in mode 4, a valid failure of l diesel generator-(D/G) A, NE01, occurred while performing surveillance

. procedure 0SP-NE-00002, Standby D/G Periodic Tests. f The surveillance was being performed to show the operability of D/G A 'since it had been-

. out-of-service due to a maintenance' outage for NB01,-the corresponding 4160 volt Class IE bus. The main feeder breaker, NB-01-11, from D/G A to NB0lffailed.to close thus constituting a valid failure of D/G A.:

Valid starts of the diesel generators have been tracked since the completion ~of:Preoperational. Testing on 5/11/84. There vere three valid' tests of D/G A between 5/11/84 and 8/12/84'and this is the first valid

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failure of either D/G.

Failure of the breaker to close appears to be~due to mechanical-binding of the manual closing. switch. This kept the latch monitoring switch open and prevented charging of the closing spring. The manual

! closing switch was apparently mechanically bound during an operational

relay check completed at 1125 on 8/11/84. During this-check the breaker was manually opened. The closing-spring was supposed to charge when the breaker was racked-in but because the manual closing switch was bound it failed to do.so. Once the-closing switch was released and the latch monitoring circuit closed, the closing spring charged automatically and operated normally. The surveillance-procedure was then completed satisfactorily at 1417 on 8/12/84. Therefore,'the D/G had been inoperable for approximately 27 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> due to the breaker. Because the z

D/G had been declared inoperable for the NB01 maintenance outage,.

failure of the breaker did not in and of itself require entry into a Technical Specification Action Statement.

After the closing switch was reset, the breaker functioned automatically with no problem. Therefore, this particular failure is considered an isolated case.

i Currently, surveillance tests are performed 'at least once per 31 days. This is in conformance with the schedule of Regulatory Position C.2.d which requires the test interval to be noc more than 31 days if the number of failures in the last 100 valid tests is one or zero, i~

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