ML20085M400

AO BFAO-7347W:on 731219,during Outage for Maint,Standby Emergency Diesel Generator a Failed to Start Emergency Core Cooling Pump.Caused by Voltage Regulator Failure.Voltage Regulator Replaced

ML20085M400
Person / Time
Site:	Browns Ferry
Issue date:	12/28/1973
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085M402	List: ML20085M400 ML20085M404
References
AO-BFAO-7347W, NUDOCS 8311080442
Download: ML20085M400 (4)

Text

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. i Z 1. Q TENNESSEE CHATTANOOGA,VALLEYTENNESSEE AtJTHCAITY IiF33 - i' 37401 U t . 41

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lir. John F. O' Leo.ry, Director M~

, f Directorate of Licensing & i W office of Regulation D' U.S. Atomic D.ergy Co= mission Washington, DC 20545

Dear Mr. O' Leary:

TEIUESSEE VALLEY AUTHORITY - BROWNS FERRY UUCLEAR PLAUT UNIT 1 -

DOCKET UO. 50-259 - FACILITY OPERATING LICENSE DPR ABNWAL OCCURRENCE REPORT BFAO-7347W The enclosed report is to provide details concerning standby emergency diesel generator failure to start en emergency core cooling pu=p which occurred on Bro.ms Ferry nuclear Plant unit 1 on December 19, 1973, and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973

, Very truly yours, TENNESSEE VALLEY AUTHORITY le'YP , W E. F. Thomas Director of Power Production i

Enclosure

. CC (Enclosure):

Mr. Ucrman C. l'oseley, Director.

Region II Regulatory Operations Office, USAEC 230 Peachtree Street, UW. -

Atlanta, Georgia 30303~

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0311080442 731228 7(Al -

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COPY SENT REGION 70 ~ ; .

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1. wk ABNORMAL OCCURRENCE REPORT

. Report No. --BFAO-73hT4 .

. Report Date--December 28, 1973 Occurrence Date--December 19, 1973 Facility--Browns Ferry Nuclear Plant Identification of Occurrence Standby emergency diesel generator failure to start an emergency core cooling pump.

Conditions Prior to Occurrence ,

The reactor was shut down in the cold depressurized condition for short-term outage-maintenance.

Descriution of Occurrence During the unit 1 outage, preoperational testing was being conducted on unit 2.

In the performance of the preoperational testing, it was discovered that diesel generator A which serves both units 1 and 2 could not. start and accelerate residual heat removal pu=p 2A. The pump motor would trip on overcurrent.

Designation of Antarent Cause of Occurrence The diesel generator voltage regulator failed permitting the generator output voltage to drop and not recover during the start of the 2,000-horsepower RHR pump.

Analysis of Occurrence

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In the cold shutdown condition only two RER pumps and their associated diesels are required t'o be operable. Three diesel generators and all other components of the emergency core cooling systems were operable.

Corrective Action e

Following the discovery of this occurrence, investigative testing was' perform'd on diesel generator A to prove that the voltc6e regulator was solely responsible for the failure to accelerate the RHR pump. During the testing,.it was proven that the> diesel generator could provide its naceplate rating of power when paralleled ,

with the TVA transmission system and that it could properly start and-accelerr.te smaller emergency cooling pumps such as a core spray pump (600 horsepower) and an emergency equipment coolin5 water pump (400' horsepower).

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Following the testing,'the voltcGe. regulator was replaced and sufficient tests were performed to prove that diesel generator A would start and accelerate all of its.

assigned emergency core cooling loads in the required time.

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Failure Data This is the first failure of a diesel generator voltage regulator at Browns Ferry Nuclear Plant. The voltage regulator is r.anufactured by Basler Electric Co=pany, part No. 90 49000100, serial no. 56.

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All Regional Branch Chiefs except X I Region II TEtilIESSEE VALLEY AUTHORITY (BROWNS FERRY #1)

DOCKET NO. 50-259 - ABUORMAL OCCURRENCE l X REPORT BFAO-7347W l

X The subject report is forwarded for your coneral infomation.

Enclosure:

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