ML072680590
| ML072680590 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 09/27/2007 |
| From: | Mahesh Chawla NRC/NRR/ADRO/DORL/LPLIII-1 |
| To: | Wadley M Nuclear Management Co |
| muniz A, ADRO/DORL/415-4044 | |
| References | |
| TAC MD3158 | |
| Download: ML072680590 (5) | |
Text
September 27, 2007 Mr. Michael D. Wadley Site Vice President Prairie Island Nuclear Generating Plant Nuclear Management Company, LLC 1717 Wakonade Drive East Welch, MN 55089
SUBJECT:
PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNIT 1 - REVIEW OF THE 2006 STEAM GENERATOR TUBE INSPECTION REPORT (TAC NO. MD3158)
Dear Mr. Wadley:
By letters dated May 25, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML061450543), September 1, 2006 (ADAMS Accession No. ML062550530), and September 7, 2007 (ADAMS Accession No. ML072500386), Nuclear Management Company (NMC, the licensee) submitted information summarizing the results of the 2006 steam generator tube inspections at Prairie Island Nuclear Generating Plant (PINGP),
Unit 1. These inspections were performed during the 24th refueling outage (1R24). In addition to these reports, the U.S. Nuclear Regulatory Commission (NRC) staff summarized additional information obtained during a May 18, 2006, conference call concerning the 2006 steam generator tube inspections at PINGP. The information is discussed in a letter dated July 10, 2006 (ADAMS Accession No. ML061680006). Licensee provided additional information via e-mail on September 24, 2007 (ADAMS Accession No. ML072690050).
As discussed in the enclosed review, the NRC staff concluded that NMC provided the information required by the technical specifications for PINGP and did not identify any technical issues that warranted follow-up action at this time. If you have any questions regarding this matter, please contact me at (301) 415-8371.
Sincerely,
/RA/
Mahesh L. Chawla, Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-282
Enclosure:
As stated cc w/encl: See next page
ML062550530), and September 7, 2007 (ADAMS Accession No. ML072500386), Nuclear Management Company (NMC, the licensee) submitted information summarizing the results of the 2006 steam generator tube inspections at Prairie Island Nuclear Generating Plant (PINGP),
Unit 1. These inspections were performed during the 24th refueling outage (1R24). In addition to these reports, the U.S. Nuclear Regulatory Commission (NRC) staff summarized additional information obtained during a May 18, 2006, conference call concerning the 2006 steam generator tube inspections at PINGP. The information is discussed in a letter dated July 10, 2006 (ADAMS Accession No. ML061680006). Licensee provided additional information via e-mail on September 24, 2007 (ADAMS Accession No. ML072690050).
As discussed in the enclosed review, the NRC staff concluded that NMC provided the information required by the technical specifications for PINGP and did not identify any technical issues that warranted follow-up action at this time. If you have any questions regarding this matter, please contact me at (301) 415-8371.
Sincerely,
/RA/
Mahesh L. Chawla, Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-282
Enclosure:
As stated cc w/encl: See next page DISTRIBUTION PUBLIC LPL3-1 R/F RidsNrrDorlLpl3-1 RidsNrrLATHarris RidsNrrDciCsgb RidsNrrPMAMuniz RidsRgn3MailCenter KKarwoski, NRR RidsOgcMailCenter RidsAcrsAcnwMailCenter RidsNrrPMMChawla ADAMS ACCESSION NO.: ML072680590 OFFICE NRR/LPL3-1/PM NRR/LPL3-1/PM NRR/LPL3-1/LA CSGB/BC NRR/LPL3-1/(A)BC NAME AMuniz MChawla THarris AHiser TTate DATE 09/27/07 09/27/07 09/27/07 9/27/07 09/27/07 UNITED STATES NUCLEAR REGULATORY COMMISSION REVIEW OF 2006 STEAM GENERATOR TUBE INSPECTION REPORT PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNIT 1 DOCKET NO. 50-282 By letters dated May 25, 2006 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML061450543), September 1, 2006 (ADAMS Accession No. ML062550530), and September 7, 2007 (ADAMS Accession No. ML072500386), Nuclear Management Company (the licensee) submitted information summarizing the results of the 2006 steam generator (SG) tube inspections at Prairie Island Nuclear Generating Plant (PINGP), Unit 1. These inspections were performed during the 24th refueling outage (1R24). In addition to these reports, the U.S. Nuclear Regulatory Commission (NRC) staff summarized additional information obtained during a May 18, 2006, conference call concerning the 2006 steam generator tube inspections at PINGP. The information is discussed in a letter dated July 10, 2006 (ADAMS Accession No. ML061680006). The licensee provided additional information via e-mail on September 24, 2007 (ADAMS Accession No. ML072690050).
PINGP has two Framatome/AREVA model 56/19 replacement recirculating SGs. Each SG has 4,868 thermally-treated Alloy 690 tubes which have an outside diameter of 0.750 inch and a nominal wall thickness of 0.043 inch. The tubes were hydraulically expanded at each end for the full depth of the tubesheet. The tubes are supported by support plates and antivibration bars (AVBs). All tube support plates are constructed from Type 410 stainless steel. The tube support plates have a minimum thickness of 1.18 inch (and a nominal thickness of 1.25 inch) and have quatrefoil-shaped holes through which the tubes pass. The AVBs are constructed from Type 405 stainless steel and are rectangular in cross section (0.5 inch by 0.3 inch).
The 2006 SG tube inspection was the first inservice inspection of these replacement SGs.
The licensee provided the scope, extent, methods, and results of the PINGP tube inspections in the documents referenced above. In addition, the licensee described corrective actions (i.e.,
tube plugging) taken in response to the inspection findings.
The NRC staff has the following notes/observations as a result of reviewing the information provided by the licensee:
During the 2006 SG tube inspections, the licensee found more wear indications than they expected. Wear indications were generally not expected since operating experience from similarly designed SGs in other countries (primarily France) has not shown a significant number of tubes affected by wear.
This lack of wear indications in the SGs in other countries may be a result of the rules used to analyze the eddy current data. This is based on a statement from the licensee that wear indications similar to those observed at PINGP would not be detected using the French data analysis rules. Investigations into the root cause are still on-going; however, a number of corrective actions have been identified. One corrective action is to inspect the SG during the next Unit 1 outage (i.e., 1R25).
ENCLOSURE
There is no distinct axial or radial pattern for the wear indications within the SG tube bundle. The maximum depth of the approximately 105 wear indications was 21 percent through-wall. The wear indications on the tubes are located both where the tube passes through the tube support plates and at the AVBs.
A main condenser tube leak during the cycle prior to the 2006 outage resulted in a secondary side water chemistry excursion. No Electric Power Research Institute chemistry guideline action levels were exceeded.
Corrected information concerning the 1R24 Inservice Inspection Summary Report was electronically submitted via e-mail on September 24, 2007. The NRC staff review found it to be acceptable.
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.
Prairie Island Nuclear Generating Plant, Units 1 and 2 cc:
Jonathan Rogoff, Esquire Tribal Council Vice President, Counsel & Secretary Prairie Island Indian Community Nuclear Management Company, LLC ATTN: Environmental Department 700 First Street 5636 Sturgeon Lake Road Hudson, WI 54016 Welch, MN 55089 Manager, Regulatory Affairs Nuclear Asset Manager Prairie Island Nuclear Generating Plant Xcel Energy, Inc.
Nuclear Management Company, LLC 414 Nicollet Mall, R.S. 8 1717 Wakonade Drive East Minneapolis, MN 55401 Welch, MN 55089 Michael B. Sellman Manager - Environmental Protection President and Chief Executive Officer Division Nuclear Management Company, LLC Minnesota Attorney General=s Office 700 First Street 445 Minnesota St., Suite 900 Hudson, MI 54016 St. Paul, MN 55101-2127 Douglas E. Cooper U.S. Nuclear Regulatory Commission Senior Vice President and Chief Resident Inspector's Office Nuclear Officer 1719 Wakonade Drive East Nuclear Management Company, LLC Welch, MN 55089-9642 700 First Street Hudson, WI 54016 Administrator Goodhue County Courthouse Joel P. Sorenson Box 408 Director, Site Operations Red Wing, MN 55066-0408 Prairie Island Nuclear Generating Plant Nuclear Management Company, LLC Commissioner 1717 Wakonade Drive East Minnesota Department of Commerce Welch, MN 55089 85 7th Place East, Suite 500 St. Paul, MN 55101-2198 July 2006