ML102350170

Review of the Results of 16th Steam Generator Tube Inservice Inspections Performed During Refueling Outage 17

ML102350170
Person / Time
Site:	Wolf Creek
Issue date:	09/15/2010
From:	Balwant Singal Plant Licensing Branch IV
To:	Matthew Sunseri Wolf Creek
Singal, Balwant, 415-3016, NRR/DORL/LPL4
References
TAC ME3774
Download: ML102350170 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 15, 2010 Mr. Matthew W. Sunseri President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839

SUBJECT:

WOLF CREEK GENERATING STATION - REVIEW OF THE RESULTS OF THE 16TH STEAM GENERATOR TUBE INSERVICE INSPECTIONS PERFORMED DURING REFUELING OUTAGE 17 (TAC NO. ME3774)

Dear Mr. Sunseri:

By letter dated April 8, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML101100676), as supplemented by letter dated July 15, 2010 (ADAMS Accession No. ML102080031), Wolf Creek Nuclear Operating Corporation (the licensee) submitted information summarizing the results of the 16th steam generator tube inservice inspections at the Wolf Creek Generating Station (WCGS), performed during Refueling Outage 17.

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 WCGS Technical Specifications and that no additional follow-up is required at this time. The results of the NRC staff's review of the report submitted by the licensee are summarized in the enclosure to this letter. Please contact me at 301-415-3016 with any questions.

Sincerely, R _~ t \.0 C\ '-'.-f L& ll--!~

~~ant K. Singal, Senior Projec1' Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-482 Enclosure As stated cc w/encl: Distribution via Listserv

OFFICE OF NUCLEAR REACTOR REGULATION REVIEW OF THE RESULTS OF THE 16TH STEAM GENERATOR TUBE INSERVICE INSPECTIONS PERFORMED DURING 17TH REFUELING OUTAGE WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482 By letter dated April 8,2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML101100676), as supplemented by letter dated July 15, 2010 (ADAMS Accession No. ML102080031), Wolf Creek Nuclear Operating Corporation (the licensee) submitted information summarizing the results of the 16th steam generator (SG) tube inservice inspections at the Wolf Creek Generating Station (WCGS), performed during Refueling Outage 17.

WCGS has four Westinghouse Model F SGs. Each SG contains 5,626 thermally-treated Alloy 600 tubes. Each tUbe has an outside diameter of 0.688 inches and a wall thickness of 0.040 inches. The tubes are supported by stainless steel tube supports with quatrefoil-shaped holes and V-shaped chrome-plated Alloy 600 anti-vibration bars.

The licensee provided the scope, extent, methods, and results of its SG tube inspections in the documents referenced above. In addition, the licensee described corrective actions, such as tube plugging, taken in response to the inspection findings.

After reviewing the information provided by the licensee, the U.S. Nuclear Regulatory Commission (NRC) staff has the following comments or observations:

• The licensee has previously identified 31 tubes in SG A, 11 tubes in SG B, 10 tubes in SG C, and 7 tubes in SG D that are considered tubes with potentially elevated residual stress. The dents, dings, and expansion transitions in these tubes are not preferentially examined with a rotating probe. The NRC staff notes that several licensees do preferentially sample these locations since they may be more prone to cracking.

• The licensee does not appear to inspect all new dents and dings with a rotating probe when they are discovered. However, the licensee is maintaining the tube integrity. The NRC staff notes that several licensees inspect new dents and dings with a rotating probe to ensure degradation is not occurring at these locations (before placing these dents and dings in the general population of dents and dings).

Enclosure

-2

• Degradation has been observed at a few J-nozzle-to-feedwater ring interface locations. The licensee stated that periodic visual inspections and ultrasonic measurements are performed at these locations and all results have met the acceptance criteria. No other degradation has been observed during the secondary side inspections.

Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by the technical specifications. In addition, the NRC staff concludes that there are no technical issues that warrant follow-up actions 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: Aloysius O. Obodoako, NRR/DCI/CSGB

September 15, 2010 Mr. Matthew W. Sunseri President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839

SUBJECT:

WOLF CREEK GENERATING STATION - REVIEW OF THE RESULTS OF THE 16TH STEAM GENERATOR TUBE INSERVICE INSPECTIONS PERFORMED DURING REFUELING OUTAGE 17 (TAC NO. ME3774)

Dear Mr. Sunseri:

By letter dated April 8, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML101100676), as supplemented by letter dated July 15, 2010 (ADAMS Accession No. ML102080031), Wolf Creek Nuclear Operating Corporation (the licensee) submitted information summarizing the results of the 16th steam generator tube inservice inspections at the Wolf Creek Generating Station (WCGS), performed during Refueling Outage 17.

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 WCGS Technical Specifications and that no additional follow-up is required at this time. The results of the NRC staffs review of the report submitted by the licensee are summarized in the enclosure to this letter. Please contact me at 301-415-3016 with any questions.

Sincerely, IRN Balwant K. Singal, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-482 Enclosure As stated cc w/encl: Distribution via Listserv DISTRIBUTION:

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