ML13032A235

Review of the October 2011 Steam Generator Tube Inservice Inspections During End-of-Cycle 25 Refueling Outage

ML13032A235
Person / Time
Site:	Oconee
Issue date:	02/05/2013
From:	Boska J Plant Licensing Branch II
To:	Gillespie P Duke Energy Carolinas
Boska, J P
References
TAC ME8435
Download: ML13032A235 (3)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 february 5, 2013 Mr. Preston Gillespie Site Vice President Oconee Nuclear Station Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672-0752

SUBJECT:

OCONEE NUCLEAR STATION, UNIT 2, REVIEW Of THE OCTOBER 2011 STEAM GENERATOR TUBE INSERVICE INSPECTIONS DURING END-Of-CYCLE 25 REfUELING OUTAGE (TAC NO. ME8435)

Dear Mr. Gillespie:

By letter dated february 29, 2012 (Agencywide Documents Access Management System (ADAMS) Accession No. ML12066A243), as supplemented by letter dated October 25,2012 (ADAMS Accession No. ML12300A418), Duke Energy Carolinas, LLC., the licensee, submitted information to the U.S. Nuclear Regulatory Commission (NRC) summarizing the results of the October 2011 steam generator (SG) tube inspections performed during the End-of-Cycle 25 (EOC25) refueling outage at Oconee Nuclear Station, Unit 2 (ONS 2).

The NRC staff has completed its review of the report and concludes that the licensee provided the information required by the ONS 2 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,

~;::S~Manager (jt.~ ~i!nSing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-270

Enclosure:

As stated cc w/encl: Distribution via Listserv

OCONEE NUCLEAR STATION, UNIT 2

SUMMARY

OF THE NRC STAFF'S REVIEW OF THE STEAM GENERATOR TUBE INSERVICE INSPECTIONS FOR THE 2012 REFUELING OUTAGE DOCKET NO. 50-270 By letter dated February 29,2012 (Agencywide Documents Access Management System (ADAMS) Accession No. ML12066A243), as supplemented by letter dated October 25,2012 (ADAMS Accession No. ML12300A418), Duke Energy Carolinas, LLC, the licensee, submitted information to the U.S. Nuclear Regulatory Commission (NRC) summarizing the results of the October 2011 steam generator (SG) tube inspections performed during the End-of-Cycle 25 (EOC25) refueling outage at Oconee Nuclear Station, Unit 2 (ONS 2).

ONS 2 is a two-loop pressurized-water reactor with two once-through steam generators (OTSGs) manufactured by Babcock & Wilcox (B&W), Canada. The ONS 2 OTSGs are replacement OTSGs that were installed during the 2004 refueling outage. Each OTSG has 15,631 thermally-treated Alloy 690 tubes that have been hydraulically expanded into the tubesheets to a depth of 13 inches. There are 15 tube support plates (TSP) made of Type 410 stainless steel with trefoil shaped holes. However, there are some round drilled openings at the 14th TSP.

The licensee provided the scope, extent, methods, and results of their SG tube inspections in the documents referenced above. In addition, the licensee described corrective actions (e.g., tube plugging) taken in response to the inspection findings. The tubes in both SGs were inspected this outage. Widespread wear degradation of the tubing at TSP locations has been observed at all three Oconee units, and the affected tubes are plugged when they reach the limit on wear.

Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by the Technical Specifications. In addition, the 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

ML12300A418), Duke Energy Carolinas, LLC., the licensee, submitted information to the U.S. Nuclear Regulatory Commission (NRC) summarizing the results of the October 2011 steam generator (SG) tube inspections performed during the End-of-Cycle 25 (EOC25) refueling outage at Oconee Nuclear Station, Unit 2 (ONS 2).

The NRC staff has completed its review of the report and concludes that the licensee provided the information required by the ONS 2 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, IRA!

John P. Boska, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-270

Enclosure:

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

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