ML090710250

Prairie Island Nuclear Generating Plant, Unit 1 - Review of the 2008 Steam Generator Tube Inspection Report (TAC No. MD9684)

ML090710250
Person / Time
Site:	Prairie Island
Issue date:	03/16/2009
From:	Wengert T J Plant Licensing Branch III
To:	Wadley M D Northern States Power Co
Wengert, Thomas J, NRR/DORL, 415-4037
References
TAC MD9684
Download: ML090710250 (4)

Text

UNITED NUCLEAR REGULATORY WASHINGTON, D.C. 20555-0001 March 16, 2009 Mr. Michael D.

Wadley Site Vice President Prairie Island Nuclear Generating Plant Northern States Power Company -Minnesota 1717 Wakonade Drive East Welch, MN 55089 PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNIT 1 -REVIEW OF THE 2008 STEAM GENERATOR TUBE INSPECTION REPORT (TAC NO. MD9684)

Dear Mr. Wadley:

By letter dated September 8, 2008 (Agencywide Documents Access and Management System Accession No. ML082520615), Nuclear Management Company, LLC, a predecessor license holder to Northern States Power Company, a Minnesota company (NSPM) submitted information summarizing the results of the 2008 steam generator tube inspections at Prairie Island Nuclear Generating Plant (PINGP), Unit 1. These inspections were performed during the 25th refueling outage (1R25).

As discussed in the enclosed review, the U.S.

Nuclear Regulatory Commission staff concluded that NSPM provided the information required by the PINGP technical specifications 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) 415-4037.

Sincerely, Thomas J. Wengert, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-282

Enclosure:

As stated cc w/encl:

Distribution via ListServ UNITED STATES NUCLEAR REGULATORY COMMISSION REVIEW OF 2008 STEAM GENERATOR TUBE INSPECTION REPORT PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNIT 1 DOCKET NO. 50-282 By letter dated September 08, 2008 (Agencywide Documents Access and Management System Accession No. ML082520615), Nuclear Management Company LLC, a predecessor license holder to the Northern States Power Company, a Minnesota company (the licensee), submitted information summarizing the results of the 2008 steam generator (SG) tube inspections at Prairie Island Nuclear Generating Plant (PINGP) Unit 1. These inspections were performed during the zs" refueling outage (1R25). PINGP Unit 1 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 2008 SG tube inspection was the second inservice inspection of these replacement SGs. The licensee provided the scope, extent, methods, and results of the PINGP Unit 1 tube inspections in the document referenced above. In addition, the licensee described corrective actions (i.e., tube plugging) taken in response to the inspection findings. The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the information provided by the licensee and held a conference call with the licensee on December 22, 2008, to clarify several items in the report. These clarifications were: During the 2008 steam generator tube inspections, additional wear indications at the AVBs and at the tube support plates were detected. Many of the new indications were small. No corrosion or degradation was observed during the secondary side inspections.

The thin layer of debris (sludge) on the loose part trapping system screen was removed by scrubbing and was left in a clean condition. The only loose part detected in the steam generator was the inspection port gasket. This gasket was removed. During the inspection of the tube plugs, there was no evidence of leakage and all of the tube plugs still appeared to be adequately installed.

Enclosure

-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 and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.

March 2009 Mr. Michael D.

Wadley Site Vice President Prairie Island Nuclear Generating Plant Northern States Power Company -Minnesota 1717 Wakonade Drive East Welch, MN 55089 PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNIT 1 -REVIEW OF THE 2008 STEAM GENERATOR TUBE INSPECTION REPORT (TAC NO. MD9684)

Dear Mr. Wadley:

By letter dated September 8, 2008 (Agencywide Documents Access and Management System Accession No. ML082520615), Nuclear Management Company, LLC, a predecessor license holder to Northern States Power Company, a Minnesota company (NSPM) submitted information summarizing the results of the 2008 steam generator tube inspections at Prairie Island Nuclear Generating Plant (PINGP), Unit 1. These inspections were performed during the zs" refueling outage (1R25).

As discussed in the enclosed review, the U.S. Nuclear Regulatory Commission staff concluded that NSPM provided the information required by the PINGP technical specifications 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) 415-4037.

Sincerely, IRAJ Thomas J. Wengert, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-282

Enclosure:

As stated cc w/encl:

Distribution via ListServ DISTRIBUTION:

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