ML20038A020

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AO 07-75:on 750213,dye Penetrant Insp Indicated 30-inch Longitudinal Surface Defect.Caused by Occlusion During Mfg Stage
ML20038A020
Person / Time
Site: Big Rock Point File:Consumers Energy icon.png
Issue date: 02/24/1975
From: Sewell R
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
Office of Nuclear Reactor Regulation
References
NUDOCS 8109100424
Download: ML20038A020 (3)


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i Consumers Power Company

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Division of React.or Licensing Re: Docket 50-155 US Nuclear Regulatory Commission License DPR-6 Wachington, DC 20555 Big Rock Point Plant Ao-7-75 Gentlemen:

1 gj Attached is an Abnormal Occurrence Report describing an event involving discovery of a defect in the Big Rock Point emergency condenser s

(('j outlet pipe.

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The report is incomplete at this time. A portion of the affected pipe has been removed for metallographic examination to determine the cause of the defect. This examine. tion has not been completed at this writing.

@g Following completion of the metallographic examination, a supplemental re-port will be sub=itted.

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Yours very truly,

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Ralph B. Sevell (Signed) 72 4.i:J 3.y-lg RB3/ds Ralph B. Sevell

.N e Nuclear Licensinf Administrator

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-ABNORMAL ~ OCCURRENCE REPORT YC7"MQd[.h W7~

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Report Number: A0-7-TS, Docket 50-155 4$

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Report Date: February 24,1975

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2b. Occurrence Date: February 13.'19T5 m.

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Facility: Big Rock Point Plant 3.

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~ Identification of Occurrence: Emergency condenser outlet pipe defr.ct.

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Conditions Prior to Occurrence: Cold shutdov.: for maintenance activ-b ities. Emergency condenser pipe velding associated with the repair e'

job was being inspected.

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Description of Occurrence: A dye penetrant inspection of the 4" out-Sj let pipe near the connection to the north tube bundle of the escrgency-k condenser indicated a 30" longitudinal surface defect extending on a h

slight spiral configuration in the first horizontal section or pipe E[

nearest the condenser. The maximum depth of the defect ss measured M

by ultrasonic technique is about.09" to 0.12".

It extendr fract one E

veld to within a few inches of a second veld.

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Designation of Apparent Cause of Occurrence: Preliminary evaluation indi cates the defect to be superficial and probably dt:e to nill fabrication.

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Analysis of Occurrence: This section of piping is at reactor pressure under power operation conditions and no leakage frc= the pipe has been 2

detected.

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9 Corrective Action: A section of the pipe containing the defect was 9?jl recoved and shipped to Consumers Pover Conpany laboratories for cetallo-7 graphical examination. Based on the results of the investigation l(;

conducted to date, it isconcluded that an occlusion occurrei during W

the manufacturing stage. This is based on i.he fact that the defect fd under high cagnification appears to have a blunt bottom. Cracks Q

resulting from service conditions have a sharp bottom. Further, the

-y metallographic exa=ination has shown, to date, that the depth of the defect was significantly overestimated. The depth span thus fer in the netallographic exa=ination is 0.1T".

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/9 The final results of the estallographic examination vill be reported N

following their complet nn together with any additional corrective action taken.

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Failure Data: None.

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