ML19329A166
| ML19329A166 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 12/16/1976 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Shao L Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7912300189 | |
| Download: ML19329A166 (2) | |
Text
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06 DEC 161976 Il0TE T0:
D. G. Eisenhut, Assistant Director for Operational Technology p
FROM:
L. Shao, Chief, Engineering Branch. D0R m
SUBJECT:
OC0!iEE UNITS 1 & 2 STEAM GENERATOR, TUBE LEAK OCCURP,ENCES Pursuant to the items reported in the Weekly Highlight on the steam I
generator tube leakage incidents at Oconee Units 1 & 2, we have uade a conference call, on December 13, 1976, to Duke Power Company to r
obtain additional details on the occdrence. Participants in the con-versation are F. Alneter, B. Liaiand" Don Neighbors, of HRC and Dave Holt and Bill Haller of Duke Power. The Oconee Units are Babcock &
Wilcox designed plants. The steam generators are once through vertical l
design with tube sheets at too and bottom and approximately 16,000 Inconel 600 tubes.
i Details of the conversation and the discussion are sumariced as follows:
1.
Incidents - A 1.5 gpm leak was detected on 12/4/76 at Unit 1, and a 2.0 gpm was detected at Unit 2 on 12/9/76.
Both units were sub-sequently shutdown following each leak incident.
2.
Locations of Leaks - Both leaks were found at locations about 1/2 inch lie'157'tTe top tube sheet in the superheating region.
In Unit 2, the leak is in the center of the Il-E quadrant, while in Unit 1 it was r
i near the periphery ed B generator.
t 3.
Tyoe of Crack _s r y both fiber optics and ECT, the crack in the B i
generator of Unit 2 was found to be in circumferential direction.
The location of crack initiation; whether from ID or OD, has not been detemined. Two tubes are to be pulled and examined at the B&W i'
laboratory.
The type of crack associated with the leak in Unit I has not been l
deternined.
4.
,0perational Cycles - Oconee Unit 1 has gone through about 40 to 50
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heatup and'shutEin cycles, while Unit 2 has about 25 cycles. The i
number of operational cycles riay be important in the attemtp to define i
a failure or crack initiation nechanism. The AB is about 60*F, and M is about 1350 psi from primary to secondary side of the tubing.
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- D. G. Eisenhut ;
5.
Conclusions - There are not enough data to substantiate any mechanism to inftTate the leakage. We s'pecifica11y asked them to find out the
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location of possible crack initiations (ID or 00), the cicarance between tube and tube sheet Grid the operational history with respect to the secondary water chemi; 'ry.
i The licensee has indicated tinat they will report to us as soon as i
they complete the investigation with their NSSS.
L. C. Shao. Chief Engineering Branch Division of Operating Reactors cc:
V. Stello A. Schwencer J. D. Neighbors R. Stuart F. Almeter B. Liaw 1
i Distribution:
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