05000260/LER-1980-033-03, /03L-0:on 800815,w/unit at 93% Power in Steady State Operation,Indicated Leak on RHR Heat Exchanger 2B Found During TI-36A.Probably Caused by Leaking Gasket,Due to Loose Flange Nuts as Result of Thermal Cycling & Vibration

/03L-0:on 800815,w/unit at 93% Power in Steady State Operation,Indicated Leak on RHR Heat Exchanger 2B Found During TI-36A.Probably Caused by Leaking Gasket,Due to Loose Flange Nuts as Result of Thermal Cycling & Vibration

ML18025B073
Person / Time
Site:	Browns Ferry
Issue date:	09/08/1980
From:	TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML18025B072	List: 05000260/LER-1980-033, Forwards LER 80-033/03L-0 05000260/LER-1980-033-03, /03L-0:on 800815,w/unit at 93% Power in Steady State Operation,Indicated Leak on RHR Heat Exchanger 2B Found During TI-36A.Probably Caused by Leaking Gasket,Due to Loose Flange Nuts as Result of Thermal Cycling & Vibration
References
LER-80-033-03L-02, LER-80-33-3L-2, NUDOCS 8009160440
Download: ML18025B073 (4)

LER-1980-033, /03L-0:on 800815,w/unit at 93% Power in Steady State Operation,Indicated Leak on RHR Heat Exchanger 2B Found During TI-36A.Probably Caused by Leaking Gasket,Due to Loose Flange Nuts as Result of Thermal Cycling & Vibration

Event date:
Report date:
2601980033R03 - NRC Website

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33 34 35 36 37 40 41 42 43 44 CAUSE DESCRIPTION ANDCORRECTIVE ACTIONS Q27 LThe probable cause is a leaking gasket on the'HR heat exchan er due to'oose flange nuts resulting from thermal cycling and vibration.

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8033 Technical Specification Involved 3,5.B. 5 Reported Under '1'echnical Specification

6. 7,2.b (2)

Date of Occun ence 8/j5(80 Time of Occurrence 3:35 p-m.

Unit 2

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

Conditions Prior to Occurrence:

Unit 1 96% steady state power Unit 2 93% steady state power Unit 3 97% steady state power Action specified in the Technical Specification Surveillance Requiren>ents

met, duc to inoperable egu~imcnt.,

Describe.

LPCI, 1 pump in each RHR'loop, and cross connect capabilities were available.

~A arent 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 d'amage to plant or equipment, and no resulting significant chain of events.

Corrective Action

Several modifications are being evaluated to preven't the loosening of the nuts.

A DCR has been drafted to install locking tabs for these nuts.

RHRSW monitoring will detect any release of activity.

Routine'inspection will detect heat exchanger problems; Interim corrective action consists of increased torque value on nuts.

'l:ailut'e Data:

LER BFRO-50-260/80034; BFRO-50-259/80043'FRO-50-259/78023.

>Retention:

eriod - Lifetime; Responsibility - Administrative Supervisor

>Revision:

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