05000327/LER-1980-051-01, /01T-0:on 800516,during IE Bulletin 79-14 Support Insp,Discovered That 1-CVCH-300 Was Improperly Designed.Pipe Lugs Had Moved Out of Hanger Due to Thermal Expansion. Caused by Design Error.Lugs Lengthened

/01T-0:on 800516,during IE Bulletin 79-14 Support Insp,Discovered That 1-CVCH-300 Was Improperly Designed.Pipe Lugs Had Moved Out of Hanger Due to Thermal Expansion. Caused by Design Error.Lugs Lengthened

ML19312E201
Person / Time
Site:	Sequoyah
Issue date:	05/28/1980
From:	Swearingen J TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19312E195	List: 05000327/LER-1980-051, Forwards LER 80-051/01T-0 05000327/LER-1980-051-01, /01T-0:on 800516,during IE Bulletin 79-14 Support Insp,Discovered That 1-CVCH-300 Was Improperly Designed.Pipe Lugs Had Moved Out of Hanger Due to Thermal Expansion. Caused by Design Error.Lugs Lengthened
References
IEB-79-14, LER-80-051-01T, LER-80-51-1T, NUDOCS 8006030460
Download: ML19312E201 (2)

LER-1980-051, /01T-0:on 800516,during IE Bulletin 79-14 Support Insp,Discovered That 1-CVCH-300 Was Improperly Designed.Pipe Lugs Had Moved Out of Hanger Due to Thermal Expansion. Caused by Design Error.Lugs Lengthened

Event date:
Report date:
3271980051R01 - NRC Website

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- Tennessee Valley Authority Sequoyah Nuclear Plant LER SUPPLEMENTAL INFORMATION SQRO-50-327/ 8051 Technical Specification Involved:

3.4.10 Reported Under Technical Specification 3.4.10 Date of Occurrence: 5/16/80 Time of Occurrence:

1530 CDT Unit 1 Identification and Description of Occurrence Hanger support 1-CVCH-300 was found to be improperly designed, leaving the pipe unsupported. The support is on the normal letdown from the reactor coolant system. Design analysis showed that this pipe could break in a seismic event in a location that would cause an unisolable loss of coolant accident. Therefore, action statement 3.4.10 could not be complied with.

The reactor was taken to cold shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, in accordonce with LCO 3.03.

Conditions Prior to Occurrence Reactor was in mode 3 conducting hot-functional testing.

Action Spccified in the Technical Specification Surveillance Requirements Met Due to Inoperable Equipment Action statement 3.4.10 reqaires reactor coolant integrity to be maintained.

This could not be done; therefore, accordinc to LCO 3.03, the reactor was taken to cold shutdown immediately.

Apparent Cause of Occurrence The hanger was improperly designed. The pipe lugs were too short.

During heatup the pipe lugs moved outside of the hanger bracket, causing the pipe to be unsupported. Thermal expansion of the pipe was greater than what the Division of Engineering Design had considered.

Analysis of Occurrence should a seismic event occur, the pipe could break at a location that is unisolable from loop 3 of the reactor coolant system.

This pipe is a 3-inch line.

Corrective Action

The reactor was taken to cold shutdown. The pipe lugs were redesigned by EN DES.

The lugs were made longer so as not to move out of the hanger

'during thermal ~ expansion.-

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Failure Data N/A.

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