ML20084H811

AO BFAO-7425W:on 740505,HPCI Sys Failed to Deliver Water to Reactor When Initiated on Low Water Level After Reactor Scram.No Absolute Cause Determined.Possibly Caused by Overspeed Trip of Machine

ML20084H811
Person / Time
Site:	Browns Ferry
Issue date:	05/15/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084H813	List: ML20084H811 ML20084H818
References
BFAO-7425W, NUDOCS 8305050411
Download: ML20084H811 (3)

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'b. 6 TENNESSEE - VALLEY AUTHC:4 TTY r~a " '

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-~m ammmen ,,w)y May 15, 1974

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.r.0 Mr. John F. O' Leary, Director NN gf. .,e4- by; V" Directorate of Licensing ,

~ Office of Redulation U.S. Atomic Energy Co=11ssion >

Washington, DC 203h3 .~s ,.

Dear Mr. O' Leary:

TEtiNESSEE VALLEY AUTHORITY - BROEIS FERRY HUCLEAR PLANT UNIT 1 -

DOCKET NO. 50-259 - FACILITY OPERATII;G LICENSE DPR ABNORMAL OCCURRENCE REPORT BFAO-7425W The enclosed report is to provide details concerning HPCI system which failed to deliver water to the reactor when initiated on low water level follouing a reactor seren. This event occurred on Browns Ferry Huclear Plant unit 1 on May 5, 1^//4, and is submitted'in accordance with Appendi:: A to Regulatory Guide 1.16, Revision 1, October 1973.

Very truly yours, TENNESSEE VALLEY AUTHORITY

d. <T.m E. F. Thonas ,

~ Director of Pouer Production t

Enclosure CC (Enclosure):

Mr. Normen C. Moseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtree Street, ml., Suite 618 Atlanta, Georgia 30303 e

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i ABNORI/AL OCCURRI2 ICE REPORT Report Ilo.: BFAO-7425W

~ Report Date: May 15', 1974 Occurrence Date: I?ay 5,1974 Facility: Browns Ferry ITuclear Plant unit 1 Identification of Occurrence HPCI system failed to deliver water to the reactor when initiated on low water level following a reactor scram.

Conditions Prior to Occurrence Startup testing affecting the feedvater system was being conducted. The testing caused feedwater system fluctuations and low reactor water level with a consequent scram. The unit was operating at approximately 92-percent power at the time of scran.

Description of Occurrence The HPCI system was initiated by low water level following a scram at 8:43 a.=. on

'May 5,1974. The system atte=pted to start but tripped off. It was placed on manual control and was started. It was utilized satisfactorily in the manual mode to assist in regulating vessel water level. Vnen no longer needed for service, it was shut down.

• Fonowing shutdown, it was noticed that the inverter power supply fuse alarm was annunciated. The system was declared inoperable at 10:55 a.m.

Designation of Atmarent Cause of Occurrence An investigation was conducted to determine the cause of the IECI trip. No absolute cause was determined. One possibility was an overspeed trip of the machine; however, overspeeding could not be confirmed.

Analysis of Occurrence During the brief interval between the HPCI trip and manual actuation and the period involving the failed fuse, all remaining safety systems were available.

Vessel water level was controlled at all times by other systems, and there were l no adverse consequences experienced.

Corrective Action l

The inverter power supply was checked and nothing was found amiss. The output ,

1 cads from the power supply were lifted, and the circuit was checked for grounds l or shorted conditions with all results satisfactory. The leads were connected and a new fuse satisfactorily installed. The power supply reacted satisfactorily to checks; and the system was declared operabic at 12:20 p.m. on May 5, 1974.

.The power supply will be instru=ented in order to further determine the cause of the fuse failure.

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Corrective f.ction (continued) l The HPCI operated satisfactorily when auto =atically initiated following'a ,

subsequent scram after startup on 1:cy 6,1974, at 8:26 p.r.  ;

Fcilure Data -

i Failures of 'a similar nature have been reported in BFAo-739W, BFAo-7318W, '

BFAO-7329W, and BFAO-7336W.

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