ML13151A252

Review of the Steam Generator Tube Inspection Report for the Spring 2012 Refueling Outage

ML13151A252
Person / Time
Site:	Oconee
Issue date:	06/03/2013
From:	Boska J P Plant Licensing Branch II
To:	Batson S Duke Energy Carolinas
Boska J P
References
TAC ME9449
Download: ML13151A252 (3)

Text

UNITED NUCLEAR REGULATORY WASHINGTON, D.C. 20555'()001 June 3, 2013 Mr. Scott Batson Site Vice President Oconee Nuclear Station Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672-0752 OCONEE NUCLEAR STATION, UNIT 3, REVIEW OF THE STEAM GENERATOR TUBE INSPECTION REPORT FOR THE SPRING 2012 REFUELING OUTAGE (TAC NO. ME9449)

Dear Mr. Batson:

By letter dated August 27.2012 (Agencywide Documents Access and Management Systems (ADAMS) Accession No. ML 12242A553), as supplemented by letter dated April 15, 2013 (ADAMS Accession No. ML 13109A453).

Duke Energy Carolinas, LLC., the licensee, submitted information to the U.S. Nuclear Regulatory Commission (NRC) summarizing the results of the 2012 steam generator tube inspections at Oconee Nuclear Station, Unit 3 (ONS3). In addition to this report, the NRC staff summarized a conference call about the 2012 steam generator tube inspections at ONS3 in a letter to the licensee dated June 28,2012 (ADAMS Accession No. ML 12178A206).

The NRC staff has completed its review of the report and concludes that the licensee provided the information required by the ONS3 Technical Specifications.

No additional follow up is required at this time. The NRC staff's review is enclosed.

If you have any questions, please call me at 301-415-2901.

Sincerely, hn P. Boska, Senior Project Manager lant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-287

Enclosure:

As stated cc w/encl: Distribution via Listserv OCONEE NUCLEAR STATION, UNIT 3

SUMMARY

OF THE NRC STAFF'S REVIEW OF THE STEAM GENERATOR TUBE INSERVICE INSPECTION REPORT FOR THE 2012 REFUELING OUTAGE DOCKET NO. 50-287 By letter dated August 27,2012 (Agencywide Documents Access and Management Systems (ADAMS) Accession No. ML 12242A553), as supplemented by letter dated April 15, 2013 (ADAMS Accession No. ML 13109A453), Duke Energy Carolinas, LLC., the licensee, submitted information to the U.S. Nuclear Regulatory Commission (NRC) summarizing the results of the 2012 steam generator tube inspections at Oconee Nuclear Station, Unit 3 (ONS3). In addition to this report, the NRC staff summarized a conference call about the 2012 steam generator tube inspections at ONS3 in a letter to the licensee dated June 28, 2012 (ADAMS Accession No. ML 12178A206).

ONS3 is a two-loop pressurized-water reactor with replacement once-through steam generators (ROTSGs) manufactured by Babcock & Wilcox (B&W), Canada. The ONS3 ROTSGs were installed during the fall 2004 refueling outage. The ROTSGs contain 15,631 thermally treated Alloy 690 tubes that have been hydraulically expanded into the tubesheets to a depth of 13 inches. There are 15 Type 410 stainless steel tube support plates (TSP) of trifoil broach design; however, there are some round drilled openings at the 14th TSP. The inspection performed in spring 2012, was the fifth inservice inspection of the ROTSGs. The first inservice inspection of the ROTSGs at ONS3 (spring 2006) revealed widespread wear degradation of the tubing at TSP locations.

Oconee, Units 1 and 2, have also experienced this widespread tube wear degradation at TSP locations.

During the 2012 outage, the licensee detected wear attributed to tube-to-tube contact. The wear is located in tubes with the highest compression within the ROTSGs. All but one of these wear indications is traceable back to the first inspections performed after SG replacement.

The licensee stated that the cause of the tube-to-tube wear is believed to be lateral deflection of the tubes during heat-up when the shell is cooler than the tubes. As a result of the 2012 inspections, zero tubes were plugged in ROTSG 3A and two tubes were stabilized and plugged in ROTSG 3B. Two foreign objects were found in ROTSG 3A, one on the 11 th TSP and the other on the lower tubesheet.

The object on the lower tubesheet was removed and the object on the 11 th TSP was evaluated and found acceptable to be left in the ROTSG. Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by their technical specifications.

In addition, the NRC staff concludes that there are no technical issues that warrant follow-up action at this time since the inspections appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units. Enclosure Mr. Scott Batson June 3,2013 Site Vice President Oconee Nuclear Station Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672-0752 OCONEE NUCLEAR STATION, UNIT 3, REVIEW OF THE STEAM GENERATOR TUBE INSPECTION REPORT FOR THE SPRING 2012 REFUELING OUTAGE (TAC NO. ME9449)

Dear Mr. Batson:

By letter dated August 27,2012 (Agencywide Documents Access and Management Systems (ADAMS) Accession No. ML 12242A553), as supplemented by letter dated April 15, 2013 (ADAMS Accession No. ML 131 09A453) , Duke Energy Carolinas, LLC., the licensee, submitted information to the U.S. Nuclear Regulatory Commission (NRC) summarizing the results of the 2012 steam generator tube inspections at Oconee Nuclear Station, Unit 3 (ONS3). In addition to this report, the NRC staff summarized a conference call about the 2012 steam generator tube inspections at ONS3 in a letter to the licensee dated June 28,2012 (ADAMS Accession No. ML 12178A206).

The NRC staff has completed its review of the report and concludes that the licensee provided the information required by the ONS3 Technical Specifications.

No additional follow up is required at this time. The NRC staffs review is enclosed.

If you have any questions, please call me at 301-415-2901.

Sincerely, IRA! John P. Boska, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-287

Enclosure:

As stated cc w/encl: Distribution via Listserv DISTRIBUTION:

PUBLIC LPLlI-1 R/F RidsAcrsAcnw_MailCTR Resource RidsNrrDorlDpr Resource RidsNrrDorlLpL2-1 Resource RidsNrrLASFigueroa Resource RidsNrrPMOconee Resource RidsOgcMailCenter Resource RidsRgn2MailCenter Resource RidsNrrDeEsgb Resource KKarwoski, NRR AJohnson, NRR ADAMS Accession No. ML 13151A252

"'See memo dated 5/21/13 OFFICE NRRlLPL2-1/PM NRRlLPL2-1/LA NRR/ESGB/BC*

NAME JBoska SFigueroa GKulesa RPascarelli DATE 06/03/13 06/03/13 05/21/13 06/03113 OFFICIAL RECORD COPY