ML20085H116

AO BFAO-50-260/7416W:on 740924,HPCI Inoperable Due to Blown Gasket on Gland Steam Condenser Causing Flooding of HPCI Turbine Sump & Inundating Gland Steam Condenser Hotwell Pump.Caused by Failure of Upper Head Gasket on Condenser

ML20085H116
Person / Time
Site:	Browns Ferry
Issue date:	10/04/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8308300196
Download: ML20085H116 (2)

Text

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TENNESSEE CHATTANOOGA,VALLEY AUTHO AlIY M]' .FI i-TENNESSEE *'

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~ h.b \ Ib 2tyDf i Mr. Edson G. Case 5 '

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Acting Director of Licensing Office of Regulation y QT sd um A g I U.S. Atomic Energy Cor: mission q /

Washington, DC 20545 N

Dear 1'r. Case:

i TENNESSEE VALLEY AUTHORITY - BROMITS FERRY NUCLEAR PLANT UNIT 2 - I DOCI2T NO. 50-260 - FACILITY OPERATING LICENSE DPR ABNORMAL OCCURRENCEREPORTBFAO-50-260/7416W The enclosed report is to provide details concerning the HPCI system which bece=e inoperable due to a blown gasket on the gland steam conden::er and which caused flooding of the HPCI turbine sur:o and inundated the gland steen condenser hotvell pump and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973 This event occurred on Brom:s Ferry Nuclear Plant unit 2 on September 24, 1974 Very truly yours, TENNESSEE VALLEY AUTHORITY W

E. F. Tho:::as .

Director of Power Production Enclosure CC (Enclosure):

Mr. Nor sn C. Moseley, Director Region II Regulatory Operations Office, USAEC

_ 230 Peachtree Street, NW., Suite 818 Atlanta, Georgia 30303 8308300196 741004

, DR ADOCK 05000 ,

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n ABNORl'AL OCCURRENCE REPORT 4 Report No.: BFAO-50-260/7416W Report Date: October 4, 1974 i Occurrence Date: September 24, 1974 Facility: Browns Ferry nuclear Plant unit 2 '

f Identification of Occurrence .

The HPCI system became inoperable due to a blown gasket on the gland steam condenser which caused flooding of the h7CI turbine su=p and inundated the gland  ;

steam condenser hotwell pu=p. '

Conditions Prior to Occurrence The unit was in hot shutdown condition following a reactor scram fror2 620 DTe.

Descriution of Occurrence -

The HPCI was automatically initiated following a reactor scram at 1859 hours0.0215 days <br />0.516 hours <br />0.00307 weeks <br />7.073495e-4 months <br /> on September 24, 197h. The HPCI and RCIC restored reactor water level as intended -

with no indication of trouble. A routine inspection of the area was in progress following the operation of the HPCI turbine when the operator discovered the U, upper gasket on the gland steam condenser leaking. This had caused flooding of j the su=p surrounding the HPCI turbine and consecuently flooded the gland stes:

condenser hotwell pump and solenoid valve 2-FSV-73-8.

• Designation of Antarent Cause of Occurrence The single apparent cause of the occurrence was failure of the upper head gasket on ~

the gland steam condenser. Failure of this gasket caused flooding of the surp which, in turn, caused failure of the gland steam condenser hotwell pu=p and the exhaust line drain pot drain valve 2-FSV-73-8 Failure of the hotwell pu=p contributed to floodira of the turbine exhaust line drain pot. Subsequent investigation found the exhaust line drain pot level switch to be hanging mechanically which contributed to, exhaust line flooding and failure of the level alarm.

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Analysis of Occurrence -

l Failure of the upper head gasket on the gland steen condenser which caused h7CI j to become inoperable did not jeopardi::e unit operation or create a hazard to the '

public. Other core cooling systems proved to be operable. .

,j Corrective Action '

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1. The upper head gasket on the gland steam condenser was replaced. Mechanical '

hanging of the drain pot level switch was freed. Gland steam condenser hotwell pump rntor was dried out and meggered satisfactorily.

2. The Division of Engineering Design is being asked to explore possibility of b5 a level alarm for the HPCI turbine surp. h?CI was tested ard returned to operable condition.

Failure Data # ' 4' ]

K' gnere have been no previous failures of this type. .

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