ML091550027

Reply to Request for Additional Information Concerning Steam Generator Tube Inspection Reports for End of Cycle 15 Refueling Outage

ML091550027
Person / Time
Site:	Catawba
Issue date:	05/28/2009
From:	Morris J R Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MD8402
Download: ML091550027 (5)

Text

-Duke (Energy.Carolinas JAMES R. MORRIS, VICE PRESIDENT Duke Energy Carolinas, LLC Catawba Nuclear Station 4800 Concord Road / CN01 VP York, SC 29745 803-701-4251 803-701-3221 fax May 28, 2009 U.S. Nuclear Regulatory Commission Attention:

Document Control Desk Washington, D.C. 20555 Subj ect: Duke Energy Carolinas, LLC (Duke)Catawba Nuclear Station, Unit 2 Docket Number 50-414 Reply to Request for Additional Information Concerning Steam Generator Tube Inspection Reports for End of Cycle 15 Refueling Outage (TAC Number MD8402)

References:

1. Memorandum from Allen L. Hiser, Jr. to Melanie Wong, dated June 6, 2008 (communicated to Duke via electronic mail dated August 4, 2008)2. Letter from Duke to NRC, same subject, dated December 18, 2008 Reference 2 provided Duke's response to the Reference 1 Request for Additional Information (RAI). In Reference 2, Duke indicated that Question 4 would require a supplemental response.

Accordingly, please find attached our supplemental response to this question.If you have any questions concerning this material, please call L.J. Rudy at (803) 701-3084.Very truly yours, LJR/s Attachment 400o(www. duke-energy.

com Document Control Desk Page.2 May 28, 2009 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 A.T. Sabisch, Senior Resident Inspector U.S. Nuclear Regulatory Commission Catawba Nuclear Station J.H. Thompson, Project Manager (addressee only)U.S. Nuclear Regulatory Commission Mail Stop 8 G9A Washington, D.C. 20555-0001 Document Control Desk Page 3 May 28, 2009 bxc (with attachment):

R.D. Hart L.J. Rudy P.W. Downing, Jr.D.B. Mayes C.B. Cauthen W.K. Davis K. Douthit RGC File Document Control File 801.01 ELL-ECO50 NCMPA-1 NCEMC PMPA l ATTACHMENT REPLY TO NRC REQUEST FOR ADDITIONAL INFORMATION REQUEST FOR ADDITIONAL INFORMATION CATAWBA, UNIT 2 2007 STEAM GENERATOR TUBE INSPECTIONS TAC No. MD8402 DOCKET No. 50-414 4. Please discuss the extent of tube support plate hole blockage.

In addition, discuss the results of the rotating probe examinations performed at 08H and 09C for evidence of hole blockage.Duke Response: The visual inspection previously performed during the Catawba Unit 2 End of Cycle (EOC) 15 refueling outage was inconclusive because the inspection could not see the bottom of the support plate broached holes. A more comprehensive visual inspection of the uppermost tube support plate and broached holes was performed during the EOC 16 outage in March 2009. This inspection was performed by pushing a video probe with a 90-degree adapter down the tube free lane and looking down tube columns on the hot and cold leg sides.The 90-degree adapter provided a good view of the broached openings, including a view down into the broach. Nine columns were inspected on each side of the steam generator.

It is estimated that approximately 10% of the broached openings were inspected on both the hot and-cold leg sides.Based on the visual inspection performed during the EOC 16 outage, the broached openings at the 08H and 09C support plate were found to be generally open (i.e., non-occluded).

There was no evidence of broach blockage observed from deposit build-up or so-called "coronary artery disease".There was some evidence of deposit lips beginning to form at the bottom of broached openings.

Also, a small number of openings were observed to be partially blocked by "spalled" flakes.Evaluation of the array data from the EOC 15 outage was indeterminate with regard to the extent of blockage at the 08H and 09C support locations.

Based on the comprehensive visual inspection performed at these locations during the EOC 16 outage, no further work is planned to evaluate array probe data from these locations.

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