ML20085G113

AO BFAO-50-260/751W:on 750107,RCIC Failed to Operate After Planned Turbine Trip.Caused by Electronic Overspeed Trip Due to Dropping Resistor Open Circuiting in Resistor Box. Resistor Replaced & Voltage Verified

ML20085G113
Person / Time
Site:	Browns Ferry
Issue date:	01/17/1975
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E Office of Nuclear Reactor Regulation
Shared Package
ML20085G105	List: ML20085G101 ML20085G113
References
NUDOCS 8308240292
Download: ML20085G113 (2)

Text

P AIUiORMAL OCCURRCCE REPC Report No.: BFAO-50-260/751W Report Date: Januarf 17, 1975 Occurrence Date: Januar/ 7,1975 Facility: Browns Ferry Nuclear Plant unit 2 Identification of Occurrence RCIC failure to operate.

Conditionn Prior to Occurrence A turbine trip had just been initiated at full load as part of Startup Test Instruction 27.

Description of Occurrence RCIC wac initiated following the scram and irrediately tripped. There was no speed indication, but stecnflow was observed to rise indicating that the turbine was rolline. The RCIC continued to trip in the case conner during subcequent start attemptn.

Designation of Anparent Cause of Occurrence A dropping resistor was open circuited in the recintor box which provides a 48-volt d-c power curply for the EGM control box. Therefore, the EGM control box was unable to give the ccntrol valve a closing signal resulting in an electronic overrpced trip.

Analynin of Occurrence Cafe chutdovn of the reactor was acco=plished with the re=aining engineered safeguard cystc=c. HPCI was operabic for restoration of vescel inventory as needed. The failure caused no damage to any systers, structures, or cornonents.

There were no adverse effects to the health and cafety of the public, and there vore no perconnel injuries or exposures due to this occurrence.

Corrective Action .

The renictor was replaced and voltage to the EGM control box was verified.

RCIC operability was verified by appropriate surveillance testing.

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Failure Data

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Resistor box: Woodward part No. 8270-282 Resistor: Pacific, 250 ohn, 70 watt, 3%

A previous failure of thin type on HFCI was reported in BFAO-7348W.

9309240292 S

PDR 750107PDR ADOCK 0S000260

TENNESSEE VALLEY AUTHOntTY C H A T T A N COGM- T C *i N C 5 5 M 3 7.' 01 January 17, 1975 ..'.

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1.'s. Edson G. Cace .

Actin 6 Director of Licensirg Office of Regulation U.S. Atomic Energy Co:=ission Wachington, DC 205!+5

Dear Mr. Case:

TE'TITEGSEE VALLEY IMORITY - BROM!S FERRY liUCLEt.R PLAliT UIIIT 2 -

DOCKET I;3. 50-260 - FACILIT'I OPERATII!G LICE!!SD DPR ABIiOR?'AL oCcURREI:CEREPORTBFA0-50-260/751W The encloced report is to provide details concerning RCIC failure to operate and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973. This event occurred l

on Browns Ferry I;uclear Plant unit 2 on January 7, 1975.

Very truly yours, TEIIITEUSEE VALLEY AUTiiORITY f:,/ Q s

,A,/

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E. F. Thomas Director of Powcr Production Enclocure CC (Enclosure):

Mr. Iiornan C. l'occley, Director Regiiin 11ReMtitoif'Opci-ations Office',"USAEC "

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230 reachtree street, LJ., suite 818 '

Atlanta, Georgia 30303

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