ML19329A606
| ML19329A606 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/21/1972 |
| From: | Whitesell D US ATOMIC ENERGY COMMISSION (AEC) |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| 51, NUDOCS 8001070609 | |
| Download: ML19329A606 (2) | |
Text
,
A No.
51 Date 3/21 /72 DIVISION OF CCFPLIANCE NOTIFICATION OF AN INCIDENT OR OCCUP.RENCE Facility:
DUKE POWER CCMPANY (OCONEE 1)
Problem:
At 11:00 A.M., March 20, 1972, the licensee infor=ed DRL by telephone that 21 of the 52 Inconel in-core instrument stub tubes (o.75 inch ID - schedule 160) that penetrate the bottom of the reactor vessel had broken off within the vessel. The information which follows has been obtained by the Region II (Atlanta) Compliance Office from our Co=pliance inspector who was dispatched to the Oconee site on March 21.
Our inspector reports that the 21 in-core instrument stub tubes that failed had been sheared off in the vicinity of the veld that joins the stub tube to the bottom of the vessel.
One additional stub tube had failed at this location, but was not co=pletely sheared. Five in-core instrument stub tubes vere found to have failed in the vicinity of the flow distributor plate and several other stub tubes vere bent at a point 2-3 inches above the seal veld.
In addition to the stub tube failures, a themocouple guide extending fro =
the top vessel head had 1siled and one accelerometer used in measuring vibra-tion had beco=e detached.
Pieces of the failed stub tub e have been found throughout the reactor coolant system, ran61ng in size from buchshot to pieces about 2" in diameter.
It was observed that the tube sheet and tubes in the steam Generator "A" were extensively da= aged, apparently as a result of the debris in the system. The tubes projecting above the tube sheet in steam generator "3" were also observed to be damaged and in some cases torn; hcvever, the da=cge was not as extensive as that in steam generator "A".
In addition, the the moccuples located in steas generator "3" vere found to be dataged or broken off.
The failure mode has not as yet been determined; however, the licensee believes at this time that flow induced vibration of vessel internals was the primary cause of failure.
The extent of _ the delay in the co=pletion of the pant is not known at this time; however, the licensee has infor:ed the Federal Power Co= mission that the unit vill not be available for the su==er and vinter peak loads for this year.
Action:
1.
Both the licensee and Babcock & Wilcox, the nuclear steam supplier, have initiated investigations of the matter.
2.
The licensee has been told by Compliance that a complete report on this occurrence should be submitted to DPl.
/ bra j
8001070 C7 y
.D 3 Comissioner Ramey's Technical Assistant, Cocsissioner Doub's Technical Assistant and the staff of the Joint Co=mittee on Atomic Energy have been infomed by telephone.
Contacts:
Further information on this problem may be obtained from:
X7451 D. E. Whitosell X7421 M. S. Hildreth X7421 J. G. Keppler X7356 R. H. Engelken Distribution:
Chaiman Schlesinger F. Schroeder, DRL Commissioner Ramey R. R. Maccary, DRS Commissioner Johnson S. Levine, OEA Commissioner Larson R. S. Boyd, DEL Comissioner Doub R. C. DeYoung, DEL L. M. Muntzing, DR D. K. Skovholt, DEL E. J. Bloch, DR H. R. Denton, DEL (2)
C. K. Beck, DR L. Kornblith, Jr., CO C. L. Henderson, DR R. D. O'Heill, OCR (2)
S. H. Hanauer, DR J. Fouchard, PI V. Gilinsky, DR M. Shav, RDT E. J. Bauser, JCAE J. A. Harris, PI P. A. Morris, DRL J. D. Anderson, INS S. Smiley, DML M. Biles, CS E. G. Case, DRS R. F. Fraley, ACRS (3)
C. D. W. Thornton, MIS R. L. Tedesco, DRL L. D. Lov, CO CO Regional Offices General Manager (2)
DR Reading File GeneralCounsel(2)
REG Central File Secretary (2)-
L. Rogers, REP A. Giambusso, REP D. R. Maller, REP w
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