ML20084L705

AO 50-237/1974-35:on 740730,during Cold shutdown,4-inch Crack Discovered in Feedwater Heater Drain Line 2-3508 A-10-L.Caused by Line Vibration.Crack Ground Out & Rewelded

ML20084L705
Person / Time
Site:	Dresden
Issue date:	08/06/1974
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20084L706	List: ML20084L705 ML20084L707 ML20084L712
References
558-74, NUDOCS 8305230633
Download: ML20084L705 (2)

Text

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BBS Ltr.0558-74 Dresden Nuclear Power Station -

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% k :: u-Hr. James C. Kcppler, Regional Director 2 NO5C3 Directorate of Regulatory Operations-Region III {. Q.a 4 y .'.7f U W .b 7 "jOk u, U. S. Ato:iic Energy Co=aission 799 Roosevelt Road D

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SUBJECT:

REFORT OF ABNOR!ML OCCURRENCE PER SECTION 6.6.B 0F THE TECHNICAL SPECIFICATIONS.

• CRACK IN FEED *JATER HEATER DPAIN LINE.

References:

1) Regulatory Guide 1.16 Rev.1 Appendix A a

'2) Notification of Region III of AEC Regulatory Operations Telephone: lir. F. I: aura,1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on 7/30/74.

Telegram: Mr. J. Keppler, 0820 hours0.00949 days <br />0.228 hours <br />0.00136 weeks <br />3.1201e-4 months <br /> on 7/31/74

~,) LAnwing liusiber restis rt- Ao Report Number:50-237/1974-35 Report Date: August 6,1974 Occurrence Date: July 30,1974 -

Facility: Dresden Nuclear Power Station, Morris, Illinois IDENTIFICAT_ ION OF OCCURRENCE,

, At 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> on July 30,1974 a 4" crack was discovered in line 2-3508 A-10"-L. This is the drain from 2D1 feedwater heater to 2Cl feed-water heater.

CONDITIONS PRIOR TO OCCURRENCE At 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> on July 30, 1974 Unit 2 was in cold chutdown.

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DESCRIPTION OF OCCURRENCE .

At 0100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> on July 30, 1974 condenser flow was being reversed.

Water was noted coming from this line and upon checking it was found that there was a 4" crack in this pipe. The crack was located where a pipe support is welded to the bottom of the line.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE The apparent cause of the occurrence appears to be vibration.

With the pipe support counted on the floor, line vibration could cause stress

, in this area.

ANALYSIS OF OCCURRENCE

• There was no safety hazard to the public or plant personnel due to this occurrence. This line is no part of a safety system and would not impair the safe shutdown of the reactor. This line is in an area that would not be occupied during operation when the line contait.ed' hot water. Contam-p inated water would leak to the fic,or drain system for processing in the radioactive waste disposal system.

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• r i V V A f 71* I f IN e The immediate corrective action was to grind out and reweld the crack. In addition, plans are being made to have Operational Analysis Department (OAD) inspect similar configured pipes in this area at the first available opportunity.

To prevent a similar type failure in the future, this piping is included in a vibration study now being conducted on Unit 3. Any modifica-tion to similar piping on Unit 3 that results from this study will also be made on Unit 2. .

Any additional leaks like this one can be detected by both feedwater heater malfunctions and high input to the radioactive waste ,

l disposal system via the floor drain system. In light of this and the  ;

low threat this type of failure presents to the reactor or unit operabil- i ity, the corrective action seems both sufficient and correct.  !

1 FAILURE DATA J

Line 2-350&i-10"-L i l

l There is no other failure data for this type of failure on this j system.

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! 1 Sincerely, .,  !

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'gAC p.n%,in "B. B. Stephensen'

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