ML081710359
| ML081710359 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 07/01/2008 |
| From: | Olshan L NRC/NRR/ADRO/DORL/LPLII-1 |
| To: | Baxter D Duke Energy Carolinas |
| Olshan L N, NRR/DORL, 415-1419 | |
| References | |
| TAC MD8653 | |
| Download: ML081710359 (4) | |
Text
July 1, 2008 Mr. Dave A. Baxter Vice President, Oconee Site Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672
SUBJECT:
SUMMARY
OF NRCS REVIEW OF OCONEE NUCLEAR STATION, UNIT 3, STEAM GENERATOR TUBE INSPECTION REPORT FOR THE 2007 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MD8653)
Dear Mr. Baxter:
By letter dated March 17, 2008 (ADAMS accession number ML080810048), you submitted information pertaining to the 2007 steam generator tube inspections performed at Oconee Nuclear Station, Unit 3, during the 23rd refueling outage.
Based on a review of the material that you provided, we conclude that you provided the information required by your technical specifications. In addition, we did not identify any issues that warrant additional follow-up at this time. Our review of your report is enclosed.
Sincerely,
/RA/
Leonard N. Olshan, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-287
Enclosure:
As stated cc: See next page
July 1, 2008 Mr. Dave A. Baxter Vice President, Oconee Site Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672
SUBJECT:
SUMMARY
OF NRCS REVIEW OF OCONEE NUCLEAR STATION, UNIT 3, STEAM GENERATOR TUBE INSPECTION REPORT FOR THE 2007 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MD8653)
Dear Mr. Baxter:
By letter dated March 17, 2008 (ADAMS accession number ML080810048), you submitted information pertaining to the 2007 steam generator tube inspections performed at Oconee Nuclear Station, Unit 3, during the 23rd refueling outage.
Based on a review of the material that you provided, we conclude that you provided the information required by your technical specifications. In addition, we did not identify any issues that warrant additional follow-up at this time. Our review of your report is enclosed.
Sincerely,
/RA/
Leonard N. Olshan, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-287
Enclosure:
As stated cc: See next page Distribution:
PUBLIC RidsRgn2MailCenter (JMoorman)
LPL2-1 R/F RidsNrrDorlDpr RidsNrrDorlLpl2-1 (MWong)
A. Hiser, NRR RidsNrrLAMOBrien (hard copy)
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RidsOgcRp RidsAcrsAcnw_MailCenter Accession Number: ML081710359 OFFICE NRR/LPL2-1/PM NRR/LPL2-1/LA NRR/CSGB/BC NRR/LPL2-1/BC NAME LOlshan MOBrien AHiser MWong DATE 06/24/08 06/25/08 6/16/08 07/01/08 OFFICIAL RECORD COPY
Enclosure REVIEW OF 2007 STEAM GENERATOR INSERVICE INSPECTION
SUMMARY
REPORT OCONEE NUCLEAR STATION, UNIT 3 DOCKET NO. 50-287 By letter dated March 17, 2008 (ADAMS accession number ML080810048), Duke Energy Carolinas, LLC (the licensee) submitted information pertaining to the 2007 steam generator (SG) tube inspections performed at Oconee Nuclear Station, Unit 3 (Oconee Unit 3) during the 23rd refueling.
Oconee Unit 3 is a two-loop pressurized-water reactor with once-through steam generators (OTSGs) manufactured by Babcock & Wilcox (B&W), Canada. The Oconee Unit 3 OTSGs are replacement OTSGs that were installed during the fall 2004 refueling outage. The replacement SGs consist of 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) with trefoil-shaped holes. However, there are some round drilled openings at the 14th TSP. The 2007 inspections at Oconee Unit 3 were the second inservice inspections of the replacement OTSGs.
The first inservice inspection of the replacement SGs at Oconee Unit 3 in spring 2006 revealed widespread wear degradation of the tubing at TSP locations. Oconee Unit 1 and Oconee Unit 2 have also experienced this widespread tube wear degradation at TSP locations.
The scope of inspection in 2007 was 100 percent of the active tubes in both SGs using a combination X-probe/bobbin probe (i.e., 50 percent with an X-probe and the remaining 50 percent with a bobbin probe). Selected indications were further characterized special interest inspections. Two tubes were plugged in 3A SG for tube support wear at the tube support plates (row 76 column 131 and row 79 column 132). To date, there are a total of two tubes plugged in the 3A SG and zero tubes plugged in the 3B SG.
As discussed in a public meeting on March 27, 2008 (ML080930255), 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.
The NRC staff will continue to monitor the efforts at Oconee Units 1, 2, and 3 to identify causes for managing and mitigating the degradation occurring in the steam generators.
Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by its 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.
Oconee Nuclear Station, Units 1, 2, and 3 cc:
Mr. Dave Baxter Vice President, Oconee Site Duke Power Company LLC 7800 Rochester Highway Seneca, SC 29672 Ms. Lisa F. Vaughn Associate General Counsel and Managing Attorney Duke Energy Carolinas, LLC 526 South Church Street - EC07H Charlotte, North Carolina 28202 Manager, LIS NUS Corporation 2650 McCormick Dr., 3rd Floor Clearwater, FL 34619-1035 Senior Resident Inspector U.S. Nuclear Regulatory Commission 7812B Rochester Highway Seneca, SC 29672 Mr. Henry Porter, Director Division of Radioactive Waste Management Bureau of Land and Waste Management Dept. of Health and Env. Control 2600 Bull St.
Columbia, SC 29201-1708 Mr. B. G. Davenport Regulatory Compliance Manager Oconee Nuclear Site Duke Energy Corporation ON03RC 7800 Rochester Highway Seneca, SC 29672 Ronnie L. Gardner, PMP Manager, Site Operations and Corporate Regulatory Affairs AREVA NP Inc.
An AREVA AND Siemens Company 3315 Old Forest Road OF -16 Lynchburg, VA 24501 Mr. Leonard G. Green Assistant Attorney General NC Department of Justice P.O. Box 629 Raleigh, NC 27602 Mr. R. L. Gill, Jr.
Manager - Nuclear Regulatory Issues and Industry Affairs Duke Power Company LLC 526 S. Church St.
Mail Stop EC05P Charlotte, NC 28202 Division of Radiation Protection NC Dept of Environment, Health, & Natural Resources 3825 Barrett Dr.
Raleigh, NC 27609-7721 Mr. Peter R. Harden, IV VP-Customer Relations and Sales Westinghouse Electric Company 6000 Fairview Road 12th Floor Charlotte, NC 28210 Mr. Henry Barron Group Vice President, Nuclear Generation and Chief Nuclear Officer P.O. Box 1006-EC07H Charlotte, NC 28201-1006 Mr. Charles Brinkman Director, Washington Operations Westinghouse Electric Company 12300 Twinbrook Parkway, Suite 330 Rockville, MD 20852 Ms. Kathryn B. Nolan Senior Counsel Duke Energy Carolinas, LLC 526 South Church Street - EC07H Charlotte, NC 28202