ML20249B340

PNO-76-067:on 760406,Region III Notified That Ultrasonic Reading of 100% of DAC Observed in Isolation Condenser Steam Line.Evaluation Indicates Measurement to Represent Circumferential Crack Originating at Inner Surface of Pipe

ML20249B340
Person / Time
Site:	Dresden
Issue date:	04/07/1976
From:	Roy G, Thompson D, Warnick R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PNO-76-067, PNO-76-67, NUDOCS 9806220336
Download: ML20249B340 (1)

Text

--- __v ---- y April 7, 1976 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE --PNO-76-67 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information presented is as initially received without verification or evaluation and is basically all that is known by OIE staff as of-11:30 a.m. on date of this notification.

IT SHOULD BE SPECIFICALLY NOTED THAT THIS NOTIFICATION MAY CONTAIN INFORMATION THAT LATER MAY BE DETER'IINED TO BE INACCURATE OR INCONSISTENT. AN OFFICE OF INSPECTION AND ENFORCDIENT NOTIFICATION OF AN INCIDENT OR OCCURRENCE (BLUE SHEET) SUBSEQUENTLY WILL BE ISSUED IF WARRANTED.

. Facility: Commonwealth Edison Company (Dresden Unit 2)

Subj ect: ULTRASONIC INDICATION IN ISOLATION CONDENSER STEAM LINE An ultrasonic reading of 100% of "DAC" (Distance Amplitude Correction) was observed in the isolation condenser steam line. A preliminary evaluation indicates the measurement to represent a circumferential crack originating at the inner surface of the pipe. The indication , l was observed by an NDE contractor after the safe end had been examined I l and accepted by the licensee's NDE personnel and was detected during the planned inservice inspection of the line. The crack is the second found recently in steam piping at Unit 2 (see PNO-51).

f The 14" isolation condenser line has a 316 stainless steel safe end (sensitized) attached to the reactor vessel nozzle. A short extension or " pup" piece connects the safe end to the downstream steam piping.

The observed indication is located on the bottom side of the safe

, end in the heat-affected zone of the safe end-pup piece weld. A final decision on safe end repairs is expected about April 8. The plant is currently shut down for refueling and maintenance.

l An inspector has been dispatched to the site to review the matter.

A press release has been prepared by Region III (Chicago).

Region III received notification of this occurrence by telephone - /l from the sta' tion superintendent at 4:00 p.m., April 6, 1976. I

Contact:

RFWarnick, IE x27261 GWRoy, IE x27261 DThompson, IE x27541 Distribution:

Acting Chairman Rowden Commissioner Mason S. J. Chilk, SECY S Commissioner Gilinsky C. C. Kammerer, CA G. F. Murphy, JCAE Commissioner Kennedy l L. V. Gossick, EDO E. Volgenau, OIE J. A. Harris, PA B. C. Rusche, NRR J. La Fleur, ISP T. J. McTiernan, AIA K. R. Chapman, NMSS H. K. Shapar, ELD ,

l Transmitted: P Bldg /Jid.? [; H StMl/0 /' !NBB M l/7 Luge m e i

PRELIMINARY NOTIFICATION - NOT FOR PUBLIC DISCLOSURE i '

1;,,g 9062 36 760407 '

p; PNO-76-067 pg ll

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