ML11201A273

Evaluation of 2010 (Cycle 25) Steam Generator Tube Inspections

ML11201A273
Person / Time
Site:	Oconee
Issue date:	08/02/2011
From:	Stang J Plant Licensing Branch II
To:	Gillespie P Duke Energy Carolinas
Stang J, NRR/DORL/LPL2-1, 415-1345
References
TAC ME5835
Download: ML11201A273 (3)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Augus t 2, 2011 Mr. Preston Gillespie Site Vice President Oconee Nuclear Station Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672

SUBJECT:

OCONEE NUCLEAR STATION, UNIT 3, EVALUATION OF 2010 (CYCLE 25)

STEAM GENERATOR (SG) TUBE INSPECTIONS (TAC NO. ME5835)

Dear Mr. Gillespie By letter dated February 17, 2011, (AgencyWide Documents Access And Management System Accession No. ML110530512), Duke Energy Carolinas, LLC (the licensee), submitted information summarizing the results of the 2010 SG tube inspections at Oconee Nuclear Station, Unit 3 during the Cycle 25 refueling outage.

The U.S Nuclear Regulatory Commission (NRC) staff has completed its review of these reports and concludes that the licensee provided the information required by their technical specifications and that no additional follow-up is required at this time. The NRC staff's review of the reports is enclosed.

sincerelY~

J n Stang, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-287

Enclosure:

Evaluation of SG Tube Inspections cc w/encl: Distribution via Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 OFFICE OF NUCLEAR REACTOR REGULATION EVALUATION OF THE 2010 STEAM GENERATOR (SG) TUBE INSPECTIONS PERFORMED DURING THE 2010 REFUELING OUTAGE OCONEE NUCLEAR STATION, UNIT 3 DOCKET NO. 50-287 By letter dated February 17, 2011, (Agencywide Documents Access And Management System Accession No. ML110530512), Duke Energy Carolinas, LLC, the licensee, submitted information summarizing the results of the 2010 SG tube inspections at Oconee Nuclear Station, Unit 3 (Oconee Unit 3) that were performed during refueling outage 25.

Oconee Unit 3 is a two-loop pressurized-water reactor with replacement once-through steam generators (ROTSGs) manufactured by Babcock & Wilcox (B&W), Canada. The Oconee Unit 3 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 tubesheet 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 first inservice inspection of the ROTSGs at Oconee Unit 3 (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. As a result of the 2010 inspections, five tubes were plugged in the ROTSG 3A and five tubes were plugged in the ROTSG 3B due to wear.

Based on a review of the information provided, the Nuclear Regulatory Commission staff concludes that the licensee provided the information required by their 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.

Principal Contributor: C. Hunter Date: August 2, 2011 Enclosure

ML11201A273 *Memo submitted b OFFICE NRR/LPL2-1/PM NRR/LPL2-1/LA NRR/DCI/CSGB/BC NAME JStang MO'Brien GKulesa DATE 08101/11 08/1111 08/02/11