ML20084N671

AO 50-249/75-43:on 750927,leak Discovered in Drain Line from Feedwater Heater 3D3 to Heater 3C3.Caused by Poor Weld Installation of Drain Line Pipe Support.Crack Ground Out & Pipe Rewelded

ML20084N671
Person / Time
Site:	Dresden
Issue date:	10/07/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20084N673	List: ML20084N671 ML20084N679
References
664-75, NUDOCS 8306080420
Download: ML20084N671 (2)

Text

,o Com we::lth Edison

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Addr:s eply to Post Office Box 767 Chicago, lihnois 60690 BBS Ltr. #664-75 Dresden Nuclear Power Station R.R. #1 Morris, IL 60450

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October 7, 1975 7'&'/p,)1 00 Mr. James G. Keppler, Regional Director k[

s Directorate of Regulatory Operation-Region III b,..,,c(?fg ' "@, !

U.S. Nuclear Regulatory Commission 799 Roosevelt Road g

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SUBJECT:

REPORT OF ABNORMAL OCCURRENCE PER SECTION 6.6.A 0F THE TECHNICAL SPECIFICATIONS UNIT-3 FEEDWATER HEATER 3D3 DRAIN LINE LEAK

References:

1)' Regulatory Guide 1.16 Rev. 1 Appendix A

2) Notification of Region III of U.S. Nuclear Regnatory Commission Telephone:

R. Knop, 1015 hours0.0117 days <br />0.282 hours <br />0.00168 weeks <br />3.862075e-4 months <br /> on September. 18, 1975 Telegram:

J. Keppler, 1120 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.2616e-4 months <br /> on September 29, 1975

3) Drawing Number M-351 Report Number:

50-249/75-43 Report Date: October 6, 1975 Occurrence Date: September 27, 1975 Facility:

Dresden Nuclear Power Station, Morris, Illinois IDENTIFICATION OF OCCURRENCE A leak was discovered in the drain line from feedwater' heater 3D3 to heater 3C3. This constitutes an abnormal degradation of a boundary designed to contain radioactive materials.

CONDITIONS PRIOR TO OCCURRENCE Unit-3 was operating at a steady-state power level of 2241 MWt and 750 MWe.

No testing was in progress.

DESCRIPTION OF OCCURRENCE At approximately 1445 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.498225e-4 months <br /> on September 27, 1975, the 3D3 feedwater heater drain line was found to be leaking. A hairline crack approximately 2" in length was discovered at a pipe support intersection.

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Octcbar 7, 1975

','FT'4*Mr.JamesG.Ke,ler e DESIGNATION OF APPARENT CAUSE OF OCCURRENCE The occurrence was caused by poor weld installation of the drain line pipe support. The drain line appeared to have been undercut at the pipe support during installation, resulting in a hairline crack after years of operation.

ANALYSIS OF OCCURRENCE The health and safety of the public were not threatened by this occurrence.

The leakage occurred in an area which is unoccupied during normal plant opera-tion. The floor draic system was fully capable of handling the leakage, and any airborne activity would have been monitored before being released. Tech Spec release limits were never exceeded; any release of radioactive material to the environs was too small to be detectable.

CORRECTIVE ACTION The immediate corrective action was to grind out and reweld the crack.

In addition, the other four pipe supports on the 3D3 feedwater heater drain lines were subsequently inspected and found to be secure..

FAILURE DATA A similar drain line failure occurred on Unit-2 July 20, 1975 (Report No.

50-237/75-35). A 4" crack was discovered at a pipe support intersection.

The failure was attributed to line vibration.

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B.B. Stephenson

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Superint'endent -

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