05000366/LER-1979-025-01, /01T-0 on 790223:upper & Lower Clevis Pins of Torus Vent Header Support Columns Were Displaced.Caused by Vibration.Design Change Issued & Is Being Implemented to Weld Caps to Clevis

/01T-0 on 790223:upper & Lower Clevis Pins of Torus Vent Header Support Columns Were Displaced.Caused by Vibration.Design Change Issued & Is Being Implemented to Weld Caps to Clevis

ML19305A359
Person / Time
Site:	Hatch
Issue date:	03/05/1979
From:	Thomas Greene GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19305A355	List: 05000366/LER-1979-025, Forwards LER 79-025/01T-0 05000366/LER-1979-025-01, /01T-0 on 790223:upper & Lower Clevis Pins of Torus Vent Header Support Columns Were Displaced.Caused by Vibration.Design Change Issued & Is Being Implemented to Weld Caps to Clevis
References
LER-79-025-01T, LER-79-25-1T, NUDOCS 7903130395
Download: ML19305A359 (2)

LER-1979-025, /01T-0 on 790223:upper & Lower Clevis Pins of Torus Vent Header Support Columns Were Displaced.Caused by Vibration.Design Change Issued & Is Being Implemented to Weld Caps to Clevis

Event date:
Report date:
3661979025R01 - NRC Website

text

LICENSEE EVENT HEPORT

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60 tal DOCK E T NUMdER ti3 03 EVENT DA1E 14 75 REPOH1 DATE 60 EVENT oESCRIPTION AND PROBABLE CONSEQUENCES h TTTl i Following the performance of the MSIV full closure test at 10% power, HiiP-2-10925. !

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the test.

Several of the upper clevis pins of the torus vent header suppdrt columns i 3

4 3 s ; were found to be displaced.

An underwater survey of the torus vent header support i

3 c j columns lower clevis pins revealed two of the pins were displaced an no longer can-1

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ab e of providing support. This is a non-repetitive occurrence, i

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O l The clevis pins were displaced due to vibration.

The roll Dins which rc.10.inod tha l

clevis pins were sheered becaused they were not dosioned to 3nnnort latoral inuinn I i

i caused by the vibration.

A design change was issued and is beine implemonted to I

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weld caps to the clevis to retain the clevis pins.

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NARRATIVE

REPORT FOR LER 2-79-25 On February 14, 1979, at 2143 CST, Unit 2 startup procedure HNP-2-10925, MSl? full closure test at 100% power, was performed.

An inspection of the torus interior was made following the test since main steam line safety re-lief valves were actuated.

The torus inspection revealed that several of the upper clevis pins of the torus vent header support columns were displaced.

This displacement occur-red due to lateral vibration of ti;e vent header which caused the roll pins, which retained the clevis pins, to be sheared.

An underwater diving concern, Sub Sea Surveyors, Inc., was contracted to survey the lower clevis pins of the torus vent header support columns and the SRV.ramshead tee support clevis pins.

On 2-23-79 at 1500 CST two of the lower clevis pins of the header support columns were found to be dis-placed and were no longer capable of providing support.

Design changes have been issued and a: e being implemented to weld caps to both the upper and lower clevis of the torus vent head support columns to retain the clevis pins.

There were no personnel overexposures or injuries and no release of radio-active materials as a result of this occurrence.

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