ML041110904
| ML041110904 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 04/07/2004 |
| From: | Jamil D Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC MC0957 | |
| Download: ML041110904 (4) | |
Text
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Duke ra Power A Duke Energy Company D.M. JAMIL Vice President Duke Power Catawba Nuclear Station 4800 Concord Rd. / CN01 VP York, SC 29745-9635 803 831 4251 803 831 3221 fax April 7, 2004 U.S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C. 20555
Subject:
Duke Energy Corporation Catawba Nuclear Station, Unit 2 Docket Number 50-414 Steam Generator Outage Summary Report for End of Cycle 12 Refueling Outage Reply to Request for Additional Information (TAC Number MC0957)
Reference:
Letter from NRC to Duke Energy Corporation, dated March 31, 2004 Please find attached Catawba's reply to the reference Request for Additional Information.
The format of the reply is to restate the NRC question, followed by Catawba's response.
There are no regulatory commitments contained in this letter or its attachment.
If you have any questions concerning this material, please call L.J. Rudy at (803) 831-3084.
LJR/s Attachment J~01 www. duke-energy. corn
l.--i Document Control Desk Page 2 April 7, 2004 xc (with attachment):
L.A. Reyes, Regional Administrator U.S. Nuclear Regulatory Commission, Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303 E.F. Guthrie, Senior Resident Inspector U.S. Nuclear Regulatory Commission Catawba Nuclear Station S.E. Peters, Project Manager (addressee only)
U.S. Nuclear Regulatory Commission Mail Stop 0-8 G9 Washington, D.C. 20555-0001
REQUEST FOR ADDITIONAL INFORMATION DUKE POWER COMPANY CATAWBA NUCLEAR STATION, UNIT 2 DOCKET NO. 50-414 The Nuclear Regulatory Commission (NRC) staff has reviewed the licensee's response dated February 10, 2004, to a request for additional information regarding the End of Core 12 steam generator tube inservice inspection for Catawba Nuclear Station, Unit 2.
The NRC staff has identified the following information that is needed to enable the continuation of its review.
In your response to question 3, you indicate that you preventatively plugged two tubes (2A-1-100 and 2A-1-106) with anomalous U-bend volumetric indications.
You also stated that you believe that the indications are an artifact of the plus point inspection.
A.
During previous inspections, did you perform any rotating probe examinations in the U-bend area of these tubes?
If so, discuss whether these anomalous indications were detected.
Furthermore, if they were detected in previous inspections, discuss whether the indications changed from one inspection to the next and describe the implications of the changes.
Duke Energy Corporation Response:
Both tubes were tested with the rotating coil probe in the U-bend and the signals were present in the September 1998 outage and March 2000 outage.
The tubes were not inspected in the September 2001 outage.
The volumetric indications were located in the tangent point of the U-bend. The signals are believed to be lift off associated with the tangent point.
The tangent point is a geometry change in the tube and the liftoff means that the probe is no longer in contact with the surface of the tube.
A signal can be generated giving a false positive.
From an eddy current point of view, there was not any change in the signal.
In the 2003 outage, the signal in tube 1-100 measured 28%
through wall depth (TWD) and the signal in tube 1-106 measured 21% TWD.
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B.
If you performed rotating probe examinations in these tubes in the U-bend area during previous inspections and you did not detect anomalous indications, please provide insights on what caused the current anomalous indications.
Duke Energy Corporation Response:
See response to item A.
C.
Discuss your attempts to size the anomalous indications using any variety of non-destructive examination techniques so that you could confirm that the indications did not pose a structural or leakage integrity concern.
Also, provide a justification for your conclusions that these indications are an artifact of the plus point inspection.
Duke Energy Corporation Response:
See response to item A.
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