ML110480057
| ML110480057 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/07/2011 |
| From: | Stang J Plant Licensing Branch II |
| To: | Gillespie P Duke Energy Carolinas |
| Stang J, NRR/DORL, 415-1345 | |
| References | |
| TAC ME3843 | |
| Download: ML110480057 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 March 7, 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 1, EVALUATION OF 2009 (CYCLE 25)
STEAM GENERATOR (SG) TUBE INSPECTIONS (TAC NO. ME3843)
Dear Mr. Gillespie By letter dated March 3, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML100640143), as supplemented by letter dated April 1, 2010 (ADAMS Accession No. ML100970270), Duke Energy Carolinas, LLC (the licensee), submitted information summarizing the results of the 2009 SG tube inspections at Oconee Nuclear Station, Unit 1 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, ~
n Stang, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-269
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 2009 STEAM GENERATOR (SG) TUBE INSPECTIONS PERFORMED DURING THE 2009 REFUELING OUTAGE OCONEE NUCLEAR STATION, UNIT 1 DOCKET NO. 50-269 By letter dated March 3, 2010 (Agencywide Documents Access and Management System (ADAMS), Accession No. ML100640143), and is supplemented by letter dated April 1,2010 (ADAMS Accession No. ML100970270), Duke Energy Carolinas, LLC (the licensee), submitted information summarizing the results of the 2009 SG tube inspections at Oconee Nuclear Station, Unit 1 (Oconee Unit 1). The licensee clarified a few minor points of information with respect to their inspections. The details of these clarifications are summarized below.
Oconee Unit 1 has two replacement once-through steam generators (OTSGs) designed and fabricated by Babcock and Wilcox International (B&W). These SGs were put into service in 2004. Each SG has 15,631 thermally treated Alloy 690 tubes that have a nominal outside diameter of 0.625 inches and a nominal wall thickness of 0.038 inches. The tubes were hydraulically expanded into the tubesheet for 13 inches from the tube end. The tubesheets are 22 inches thick.
The licensee provided the scope, extent, methods, and results of the SG tube inspections in the letters referenced above. In addition, the licensee described the following corrective actions (i.e., tube plugging) taken in response to the inspection findings:
- 1. UTR means "Upper Tube Region". The code is used in cases where the tube end is damaged and the probe cannot exit the tube, but the roll transition can be seen.
FL T is the code to designate flat wear.
- 2. The following tubes were plugged in the 1A OTSG:
Row Tube Row Tube Row Tube Row Tube 6
34 6
51 10 43 10 51 12 57 13 60 16 69 20 79 36 113 56 122 63 3
63 123 69 1
75 118 76 120 78 8
80 122 91 7
94 129 129 85 131 11 140 56 146 15 147 45 Enclosure
- 2 The following tubes were plugged in the 1 B OTSG:
Row Tube Row Tube Row Tube Row Tube 6
36 57 6
59 7
63 1
64 116 65 1
66 1
67 15 68 6
70 13 71 11 71 15 71 124 72 14 73 12 73 16 74 13 75 1
75 11 75 130 76 2
76 13 77 12 78 13 78 15 79 1
87 14 89 13 90 10 94 8
98 7
134 13 134 14 141 47 141 48 141 50 142 44 142 46 Widespread wear degradation of tubing at tube support plate (TSP) locations has been observed at all three Oconee units. The licensee and B&W have determined that the most probable cause of the tube wear indications at TSP locations is the tubes vibrating and impacting the tube support plates. The licensee and B&W have developed a conceptual repair, but the plugging projection model indicates that the Oconee SGs can meet their design life without implementing this repair, although a number of tubes may have to be plugged.
Based on a review of the information provided, the Nuclear Regulatory Commission (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.
Principal Contributor: C. Hunt, NRR/DCI Date: March 7, 2011
March 7, 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 1, EVALUATION OF 2009 (CYCLE 25)
STEAM GENERATOR (SG) TUBE INSPECTIONS (TAC NO. ME3843)
Dear Mr. Gillespie By letter dated March 3, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML100640143), as supplemented by letter dated April 1, 2010 (ADAMS Accession No. ML100970270), Duke Energy Carolinas, LLC (the licensee), submitted information summarizing the results of the 2009 SG tube inspections at Oconee Nuclear Station, Unit 1 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, IRA!
John Stang, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-269
Enclosure:
Evaluation of SG Tube Inspections cc w/encl: Distribution via Listserv DISTRIBUTION:
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