05000296/LER-1980-033-03, /03L-0:on 800815,during Normal Operation at Steady State Power,Unit 2B & 2D RHR Heat Exchanger Radiation Alarm Was Received.Probably Caused by Leaking Gasket Due to Loose Flange Nuts Resulting from Thermal Cycling & Vibratio

/03L-0:on 800815,during Normal Operation at Steady State Power,Unit 2B & 2D RHR Heat Exchanger Radiation Alarm Was Received.Probably Caused by Leaking Gasket Due to Loose Flange Nuts Resulting from Thermal Cycling & Vibration

ML19332A998
Person / Time
Site:	Browns Ferry
Issue date:	09/12/1980
From:	TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19332A997	List: 05000296/LER-1980-033, Forwards LER 80-033/03L-0 05000296/LER-1980-033-03, /03L-0:on 800815,during Normal Operation at Steady State Power,Unit 2B & 2D RHR Heat Exchanger Radiation Alarm Was Received.Probably Caused by Leaking Gasket Due to Loose Flange Nuts Resulting from Thermal Cycling & Vibratio
References
LER-80-033-03L-03, LER-80-33-3L-3, NUDOCS 8009190448
Download: ML19332A998 (2)

LER-1980-033, /03L-0:on 800815,during Normal Operation at Steady State Power,Unit 2B & 2D RHR Heat Exchanger Radiation Alarm Was Received.Probably Caused by Leaking Gasket Due to Loose Flange Nuts Resulting from Thermal Cycling & Vibration

Event date:
Report date:
2961980033R03 - NRC Website

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Browns Ferry Nuclear Plant BF 15.2 1/10/79 LER SUPPLEMENTAL INFORMATION BFRO -296 /

8033' Technical Specification Involved 3.5.B-12 Reported Under Technical Specification

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.Date of Occurrence 8/15/80 Time of Occurrence 1535 Unit 3

Identification and Description'of Occurrence:

During routine test TI-36A, it was found that there was an indicated leak on RHR heat exchanger 2B.

Conditions Prior to Occurren. c..e.:

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U 3 - 97% We Action specified in the Technical. Specification Surveillance Requirements met due to inoperable equipment. Describe.

I.PCI,1 pump in each RHR loop, c.nd cross connect capabilities were available.

Apparent Cause of Occurrence:

The heat exchanger has not been disassembled. Probable cause is a leaking flange gasket due to loose flange nuts caused by thermal cycling and vibration.

Analysis of Occurrence:

There was no danger to the health or safety of the,public, no damage to plant or equipment, and no resulting significant chain of events.

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Corrective Action

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Several modifications are being evaluated to prevent the loosening of the nuts.

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A DCR has been draf ted to instal.1 locking tabs for these nuts. RHRSW monitoring will detect any relea,se of activity. Routine inspection will detect heat exchanger problems. Interim action consists of increasing torque on nuts.

, Fauure Data:

BFRO-50-260/8034, 50-259/8043 and 50-259/7823.

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