NRC-90-0083, Discusses Action Plan to Review Socket Weld Failures at Plant.Failure History of Socket Welds Will Be Investigated to Determine Whether or Not Significant Common Mode Failure Mechanism Evident.Plan Expected to Be Completed by 900525

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Discusses Action Plan to Review Socket Weld Failures at Plant.Failure History of Socket Welds Will Be Investigated to Determine Whether or Not Significant Common Mode Failure Mechanism Evident.Plan Expected to Be Completed by 900525
ML20043A999
Person / Time
Site: Fermi DTE Energy icon.png
Issue date: 05/18/1990
From: Orser W
DETROIT EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-90-0083, CON-NRC-90-83 NUDOCS 9005240032
Download: ML20043A999 (2)


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  • ' > '- '1 Cilliam S. Orser '

' Vice President .

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May 18. 1990: ,

NRC-90-0083 l

-0' Ui S. Nuclear Regulatory Commission.

Attention: - ' Document ' Control Desk -(

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' Washington. D.C. 20555: } J I'

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Reference:

1) Fermi:2 j b '

NRC Docket No. 50-341- 't NRC License No. NPF-43

2) D'etroit Edison. Letter NRC-90-0053 N dated April 9. 1990 q
3) Detroit Edison Letter NRC-90-0082. . .[

4ted May 11.1990.

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Subject:

1 ,a Plan.to Review Socket Weld Problems at Fermi 2-  ;

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This. letter discusses the action plan to review socket weld' failures

,at Fermi 2.- Our' review to date of-welds other; than socket welds ' l indicates that other types of welds show no adverse trends. ~ Socket ~f I

weld failures in the Residual Heat. Removc1' system have, been addressed '

L in References 2 and 3. An ration. plan has. been developed to determine 4 l- whether socket veld f silures in other plant- systems .would' require a - i L level of corrective ; action beyond modifying or repairing them. j Detroit !Edison will investigate the failure history of the socket 'I Jwelds to determine the f ailure mechanisms involved and.whether or note j j

l a significant common mode failure mechanism is evident.

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The'investigationplaninvolves:thefo'llowingactibns: -

l' o' Identify : through the Deviation Event Report and the' work request programs, the number of similar socket weld failures  ;

since January 1.1987. Data collected from this ~ date to the 4 present will be indicative of plant operating conditions.

Prior to the-beginning of 1987, plant operating experience was limited.

o Correlate socket weld failure data with plant operating -

history through the use of plant operating histograms.

o- Collect the socket veld- f ailure data to develop a f ailure ,

profile (e.g., by system and application). 'l

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I 9005240032 900518 o '

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pDR ADOCK 05000341 'e l 1'jg PDC c

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i . uclear Reguistory Commission, May 18. 1990 NRC-90-0083 Page 2 o A metallographic analysis of one socket weld:is to'be completed on the Emergency Equipment Coolin's Water seal' water =

cooler drain valve which exhibited a pinhole porosity leak =

during weld buildup. If ' additional- . socket: weldi f ailures occur --

' within the next six months . an evaluation' of. the weld -will' be t

performed, as feasible.' contingent upon the ability to decontaminate the part or: to remove the potentially af fected' part intact (in ~ conjunction with a repair). . If 'the plant

- conditions' and radiation levels permit.1 the . fitting ,will b'e removed for analysis.- There may .be situations however. .asi there have been in the past, where :'it. is prudent to repair; the-

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p weld instead of removing the fitting.. '

o Determine the weld failure mechanism on the existing sample and compare to the .other f ailure data to determine if a common mode failure mechanism exists..

o- Perform an- evaluation to provide assurance to Detroit Edison management that a generic problem does not exist with welder qualifications. use of weld materials.- weld; proc ~edures or associated--weld inspection activities.

o Evaluate all the data collected / reviewed-on-socket weld failure mechanisms, weld pr_ocedures, technique sheets, and metallographic analysis to. determine if further: actions need-to be taken. If necessary a supplemental action plan will be established, o' Additionally.: an evaluation of' the collected data by;anl R independent welding consultant will be-performed..

This plan is tentatively expected to be completed by ~May; 25.1990.

If there are any questions concerning this matter, please contact' Barbara Siemasz. Compliance Engineer. at . (313) 586-1683..

Sincerely.

cc: A. B. Davis

' R. W. DeFayette W. R. Rogers J. F. Stang Region III -

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