05000327/LER-1980-020-01, /01T-0:on 800404,investigation Revealed That Several vendor-designed Pipe Supports Were Designed Utilizing Manufacturer Std 0.25-inch U-bolt Which Overstressed During Seismic Event.Caused by Design Error

/01T-0:on 800404,investigation Revealed That Several vendor-designed Pipe Supports Were Designed Utilizing Manufacturer Std 0.25-inch U-bolt Which Overstressed During Seismic Event.Caused by Design Error

ML19309E614
Person / Time
Site:	Sequoyah
Issue date:	04/17/1980
From:	Lagergren B TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19309E606	List: 05000327/LER-1980-020, Forwards LER 80-020/01T-0 05000327/LER-1980-020-01, /01T-0:on 800404,investigation Revealed That Several vendor-designed Pipe Supports Were Designed Utilizing Manufacturer Std 0.25-inch U-bolt Which Overstressed During Seismic Event.Caused by Design Error
References
LER-80-020-01T, LER-80-20-1T, NUDOCS 8004220707
Download: ML19309E614 (2)

LER-1980-020, /01T-0:on 800404,investigation Revealed That Several vendor-designed Pipe Supports Were Designed Utilizing Manufacturer Std 0.25-inch U-bolt Which Overstressed During Seismic Event.Caused by Design Error

Event date:
Report date:
3271980020R01 - NRC Website

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o.- o Tennessee Valley Authority Sequoyah Nuclear Plant LER SUPPLEMENTAL INFORMATION SQRO-50-327/ 8020 Technical Specification Involved SR 6.9.1.12.1 Reported Under Technical Specification 6.9.1.12.1 Date of Occurrence: 4/4/80 Tine of Occurrence: 1215' hrs. CST Unit 1 Identification and Description of Occur'rence:

Several vendor (EDS) designed pipe supports that support 3/4-inch class 'A' pipe from a larger process pipe were designed utili=ing a manufacturers standard 1/4-inch U-bolt.

Investigation has shown that this 1/4-inch U-bolt is overstressed during a seismic event based on the loadings shown on the individual drawings.

Conditiens Prior to Occurrence:

I Unit 1 in Pode 6 with all fuel loaded.

Action specified in the Technical Specification Surveillance Requirements met due to inocerable ecuineent. Describe.

N/A Apparent Cause of Occurrence:

Design error - Designer used incorrect seismic loadings in the design of the supports.

EDS designed the U-bolt in the lower (3/4-inch) pipe as an anchor -

but it was intended to be used as a 2-way lateral restraint.

Analysis of Occurrence There was no hazard to public health and safety.

Corrective Action

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The affected supports are being reviewed by SU? and EDS engineccs and will be redesigned. The U-bolts on the 3/4-inch pipes will be reanaly ad and redesigned to act as a 2-way lateral support. Modificatien vill bc =ade to the supports in the field by icosening the branch line U-bolts so they provide only lateral restraint. The modification will be ccepleted prior to initial criticality.

Failure Data:

N/A