ML20085H139

AO BFAO-50-260/7411W:on 740828,core Spray Sys 2B & 2D Pump Room Cooler Fan Motor Power Circuit Failed.Caused by Loose Terminal Block Power Connection on Inboard Side of Contractor Compartment

ML20085H139
Person / Time
Site:	Browns Ferry
Issue date:	09/06/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8308300238
Download: ML20085H139 (2)

Text

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                                                                                               '             SEp1019g s                                 h.- 7           m Mr. Edson G. Case                                                   ,; W                      24 .jNfi Acting Director of Licensing                                                       kil)
                                                                                                                                                                 ) %M Office of Regulation U.S. Atomic Ener5y Commission             ,(V a     .

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Dear Mr. Case:

{ TENNESSEE VALLEY AUTHORITY - BRO' CTS FERRY UUCLEAR PLAliT UNITi2 - DOCKCf UO. 50-260 - FACILITY OPERitTING LICEIISE DPR ABNORMAL OCCURREUCEREPORTBFAO-50-260/7411W The enclosed report is to provide details concerning failure of core spray systen 2B and 2D pump room cooler fan motor power circuit and is submitted in accordance with Appendi:c A to Regulatory Guide 1.16, Revision 1, October 1973. This event occurred on Brovns Ferry nuclear Plent unit 2 on August 28, 1974. Very truly yours, TEHNESSEE VALLEY AUTHORITY (,s -ff')

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                                                   ? > E. F. Thomas Director of Power Production
                                                 . Enclo::ure CC (Enclocuro):

Mr. Hornan C. J'oseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, NW., Suite 818 Atlanta, Georgia 30303

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q O O - ABNORPAL OCCUP.RENCE REPORT Report no.: BFAO-50-260/7h11W y Report Date: September 6, 1974 - Occurrence Date: August 28, 1974 Facility: Brouns Ferry nuclear Plant unit 2 -" Identification of Occurrence Failure of core sprcy system 23 and 2D pump room cooler fan motor power circuit. Conditions Prior to Occurrence Unit 2 was in the startup testing phase at approximately 6-percent powcr. Description of Occurrence During pelformance of routine surveillance, at opproximately 03h5 on August

      -28, it was observed that the pump room cooler fan would not operate.

Subsequent checks shoved that the air circuit breaker feeding the notor would trip about.15 seconds after energization of fan motor contactor. - Designation of Apparent Cause of Occurrence The failure vas cau::ed by a loose terminal block power connection on the inboard side of the contactor compartnent. This resulted in the "B" phase 480v power lead being burned off at the terminal block which allowed the  !? core sprey room cooler blover rotor to attempt to run single phase and therefore ' trip on overcurrent. Analysis of Occurrence Because of the failure of the cooler fan, loon II of Ihe core spray system was declared-inoperabic. The continued safe operation of the unit 2 reactor uns not jeopardised because all other safety systens as specified in technicel specification section 3.5.A.2 vere proven operable 1:cediately. There was no adverse effect on the health end safety of the public as a result of this occurrence. Corrective Action-The barned off wire was reterednated and all 'other connections in the contactor - co'.partment were checked for tightness. , Failu$c Data - None

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