ML20084E236

AO 50-237/75-14:on 750303,crack Found in Weld Between Lines 8503-8 & 1604-18.Caused by Poor Welding Technique.Weld to Be Ground Out & Pipe Reinstalled w/100% Fillet Weld

ML20084E236
Person / Time
Site:	Dresden
Issue date:	03/12/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
156-75, 2968, AO-50-237-75-14, NUDOCS 8304140462
Download: ML20084E236 (2)

Text

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. . s / ?/ Address, Wly to: Post Office Box 767 I i t' Chicago'utliois 60690 BBS Ltr. #156-75 Dresden Nuclear Power Station R. R. #1 -

Morris, Illinois 60450 March 12, 1975 Mr. James G. Keppler, Regional Director Directorate of Regulatory Operation-Region III U. S. Muclear Regulatory Co:nnission 799 Roosevelt Road Glen Ellyn, Illinois 60137 SUPJET: P2 PORT OF flf:0RT.L OCClPRECE PER SECTIO:! 6.6.A 0F THE TECH:IICAL i

' SPECIFIC .TIO:':S CRACK JN WEIS FTAED 8t03 8" AND 1604-18"

References:

1) Regulatory Guide 1.16 Rev 1 Appendix A

2) Notification of Region III of U. S. Nuclear Regulatory Con:nission Telephone: P. Jchnson, 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br /> on Ihrch 3, 1975 Telegrr.m: J. Keppler,1055 hours0.0122 days <br />0.293 hours <br />0.00174 weeks <br />4.014275e-4 months <br /> on Ihrch 4,1975

3) Drmring Hunbor: P & ID 1425 v- , u Report Number: 50-237/75-14 4-

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s' Q 'M -Ob' .c Report Date: March 12, 1975 [SY ho ('o.b) D g Occurrence Date: March 3, 1975 Q

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Facility: Drcsden Nuclear Power Station, Morris, Illinois ,h <[b [ jp' 1- ,, .;, [./

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ILE$PIPICATIO:1 OP CCCURRE' JOE- W) t 7, b ._

w!yx TG Crack in weld between lines 8503-8" and 1604-18".

CONDITIONS PRIOR TO CCCURRE*CCE Unit 2 was locked in shutdown and the drywell was open for the refueling outage.

i DESCRIPPION OF OCCURRE!CE

! On Ihrch 3.1975 maintenence was preparing the weld between lines 8503-8" and 1604-18" for radiography. The radiograph results indicated that the weld was cracked part uay through.

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8304140462 750312 PDR ADOCK 05000237 PDR 4

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Mr. James G. Keppler March 12, 1975 DESIGNATIO'I 0F APPARE T CAUSE OF OCCURRE!CE The apparent cause of the crack appears to be poor welding techrdque. When the weld vac originally made, a hole was cut into the 18" header with a torch, the 8" pipe set into it and welded in. The resultant weld was of poor quality and resulted in the crack. Review of the radiograph taken of the original weld showad the weld to be of poor quality.

ANALYSIS OF OCCURRE!CE No danger to plant perconnel or to the public existed with the reactor shutdown and the drywell open. The piping in which the crack was found is part of the nitrogen purge system for the primary containment. It is isolated from the drywell by the 1601-21 valve, from the torus by the 1601-56 valve, and from the reactor building atmosphere ly the 1601-22 valve. All of these valves are normally closed during operation.

_ CORRECTIVE ACTICN Since the unit was chutdown, no in: mediate corrective action uas reqaired.

The existing weld vill be ground out and the pipe vill be reinstalled with a 100;J fillet veld.

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FAILURE DATA Tne 2-Obuy-6" and E-1604-16" torus /drywell purse piping is of scamlcss A106 Grade B stcol of 3/8 inch wall thickness. The crack is in the weld between these two pipes.  ;.- ,-

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