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Telecopy Ro:On 740913,plant Shut Down to Investigate Source of Unidentified Leak in Drywell.Caused by Small Crack Through Pipe Wall in 4-inch Bypass Line on B-recirculation Loop.Ge Investigation Initiated
	ML20084K741
Person / Time
Site:	Dresden, 05000000
Issue date:	09/19/1974
From:	Felmus N; COMMONWEALTH EDISON CO.
To:	Robert Carlson, Dreher F; NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I), US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084K638	List: ML20084K698; ML20084K741; ML20084K773;
References
	NUDOCS 8305190532
	Download: ML20084K741 (1)
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J. D. SELBY A. P. BRAY d

SUBJECT:

RECIRCULATION LOOP" , ' '

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ON FRIDAY, SEPTEMBER 15,[1974 j

OF A 5 CPM UNIDENTIFIED LEAK IN THIS 2 THE LEAK.WASDRWELL.THE DETECIED BY DRESDEN THE G, 2 FLANT SH l

INSTALLED SUMP MONITORING (ST'SEEM.. A"SMALL CRACK;THROUCH THE PIPE WALL OlEAT EIT l

IONE) WAS DISCOVEREn ~IN THE FOUR. INCH BYPASS LINE ON,THE B-RECIRCULATION .THE LOOP.

_ CRACK-WAS-CIRCUHFERENTIALiAND IACATED EEAR THE WELDOLET ..f ATTACEE 5

RECIRCULATION AMINATION

'; AND AtlGMfSECTION[GP OPIEqP1FE FIPE. .

A TRE: DAMAGED SECTION OP.7 PIPE'WA5' REMOVED:FO INSTALLED;TO RESTORE THE LINE .TO SERVICEi j

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iMETHODS. THE BYPASS 0F ACCOMPLISHINQ?AN 'LINE!IN THE OTHER .

T DOCDIATE LOOP WAS EIAMINED'ANDiAiSIMILAR CR ARE/ REPAIRi Q* -3 M./I.5, S. W.. :g. .y g g:gM;F.:q v .. q v. %f. m e .@n.,w.co#&x.. ., J ~ . rCURRENTLY?BEING EKPLORED. #,.%

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. EKAMINE iTHESE 11NES VICENTHE AEENATj lSSUE';11DLLETIN.' REQUESTING ' OPERATORS G TT THEICPIANTjISTSHDT DWNEORiIF*THE PLANT OPERATING 'TO CONSIDER A SHUTDNN.21TH1X1934AYSMg

.CAUSE '0FiTHESELCPACKS: WILtERAVE!HORE; DEFINITE / CONCLUSIONS REGARD ~ .

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Commr~i One Firsti, th Edis n

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U Address seply to: Post Ofhee Box 767 v ". -

Chicago, Ilknois 60630 BBS Ltr.8680-74 Dresden Nuclear Power Station R. R. #1 Morris, Illinois h September 19, 197460450 g gdidlEr h iteg0 t y-/ #7 Y Mr. James G. Koppler, Regional Director Directorate of Regulatory Operations-Region III 50 P,37 sh

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U. S. Atomic Energy Cocanission ' 4% "y'3ll.1 .-

799 Roosevelt Road Glen Ellyn, Illinois 60137

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SUBJECT:

REPORT OF ABNORMAL OCCURRDJCE PER SETION 6.6.B 0F THE TECIMICAL SPIEIPICATIONS.

PRIMARY SYSTB4 LEAKS.

References:

1) Regulatory Guide 1.16 Rev.1 Appendix A

2) Notification of Region III of AEC Regulatory Operations Telephone: Mr. F. Maura,1515 heurs en septe= der..13._.1974 Telegram Mr. J. Keppler, 1543 hours0.0179 days 0.429 hours 0.00255 weeks 5.871115e-4 months on September 13, 1974

3) Drawing Number: P&ID W 26 Report Number: 50-237/1974 m 26 Report Dates September 19, 1974 Occurrence Date: September 13, 1974 Facility: Dresden Nuclear Power Station, Morris, Illinois IDDTPIPICATION OF OCCURRD'CE On September 13, 1974, a leak was discovered on line 2-0203B-4"-4 in the "B" reciro. system. The next day a leak was diccovered on line 2-0203A-4"-A in the "A" recire. system. This reprocents an abnormal degradation of a boundary designed to contain radioactive materials.

CONDITIONS PRIOR TO OCCURRB;CE

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At 1000 hours0.0116 days 0.278 hours 0.00165 weeks 3.805e-4 months on September 13, 1974, Unit 2 was in shutdown.

DESCRIPTION OP OCCURRSEE At 1000 hours0.0116 days 0.278 hours 0.00165 weeks 3.805e-4 months on September 13,~ 1974, Unit 2 was in shutdown due to high .

drywell leakage. Inspections were in progress to determine the cause of the leakage. At this time, a. leak was discovered on 2B recirc. loop at

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Mr. Jam a G. Ksppler v Ssptemb:r 19, 1974

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the connection of 2B recire. pu=p discharge valve bypass line (2-0203B-4"-A) with the recire. loop (2-0201B-28"-A). The line was cracked at the point where the line is welded to an inverted reducer. The crack was a circumfer-ential crack which ran along approximately 75% of the pipe circumference and was completely through the pipe in two areas. This crack was upstream of the bypass valve and was casily isolatible.

The next day a crack was found on the 2A recire. loop. The crack was also in the 4" equalizins line, but downstream of the bypass valve at the 28"x4" reducer to the 28" recire. riser. This crack consisted of an approximately 3/4" long circumferential crack with about a 1-1/2" tail running along the length of the pipe. Only the circumferential part of the crack was completely through the pipe. This crack was not isolatible.

DESIGNATION OF APPARFNT CAUSE OF OCCURRENCE At this time, no apparent cr.use is known. Pieces of the cracked pipe were sent out for analysis. A followup letter will be written when the results of these analyses are returned.

ANALYSIS OF OCCURRENCE There were no safety consequences to the public or plant personnel as a result of this occurrence because the cracks were found before any major damage was done. All water was contained in the drywell sumps and pumped to Raduaste for processing. The shift b,' shift monitoring of the drywell sumps found this problem immediately and allowed for a safe shutdown before excessive leakage reculted. Had the pipe broken under operation, LPCI, HFCI and core spray were available to provide core cooling.

CORRECTIVE ACTION The 2B loop crack was isolated, the section of cracked pipe cut out, and a new section welded in. The 2A loop is at the present, unisolatible. Plans are being formulated for repairing this crack. The followup letter will include the method used for repairing this crack. Subsequent investigations will be conducted on Unit 3 to disclose similar cracking at the earliest opportunity.

FAILURE DATA These are the first idlures of this type.

Sincerely, B. B. Stephenson Superintendent BBS:do

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ML20084K741

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