ML080780010

Results of Fourteenth Steam Generator Tube Inservice Inspection (Tac No. MD5946)

ML080780010
Person / Time
Site:	Wolf Creek
Issue date:	03/20/2008
From:	Donohew J NRC/NRR/ADRO/DORL/LPLIV
To:	Muench R Wolf Creek
Donohew J N, NRR/DLPM,415-1307
References
TAC MD5946
Download: ML080780010 (5)

Text

March 20, 2008 Mr. Rick A. Muench President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation Post Office Box 411 Burlington, KS 66839

SUBJECT:

WOLF CREEK GENERATING STATION - RESULTS OF FOURTEENTH STEAM GENERATOR TUBE INSERVICE INSPECTION (TAC NO. MD5946)

Dear Mr. Muench:

By letter dated March 19, 2007 (ET 07-0006), Wolf Creek Nuclear Operating Corporation (WCNOC) submitted the results of the fourteenth steam generator (SG) tube inservice inspection (ISI) performed, at Wolf Creek Generating Station (WCGS), in the fall of 2006 during refueling outage 15. As stated in the letter, the SG tube ISI report contained (1) a description of the inspections performed; (2) the location, orientation, and measured size of the service-induced indications found, and (3) the inspection results found, number of tubes plugged, and the results of condition monitoring.

The U.S. Nuclear Regulatory Commission (NRC) staff reviewed the report submitted in the March 19, 2007, letter; the WCNOC letter dated January 31, 2007, which provided the Owner's Activity Report Numbered WCRE-16, 13-PI-RF-15, on the ISI activities performed at WCGS during refueling outage 15, including the fourteenth SG tube inspections; and the WCNOC responses to NRC staff questions on these two letters. The WCNOC responses were submitted by letter dated February 28, 2008 (ET 08-0013).

Enclosed is the NRC staff evaluation of the results of the SG tube inspections conducted during refueling outage 15 at WCGS. Based on a review of the material provided by WCNOC, the NRC staff concludes that the licensee provided the information required for SG tube inspections by the plant technical specifications. In addition, the NRC staff did not identify any issues that warrant additional follow-up at this time.

Sincerely,

/RA/

Jack N. Donohew, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-482

Enclosure:

Staff Evaluation cc w/encl: See next page

ML080780010 OFFICE NRR/LPL4/PM NRR/LPL4/LA NRR/CSGB/BC NRR/LPL4/BC NAME JDonohew JBurkhardt AHiser THiltz DATE 3/19/08 3/18/08 03/10/08 3/20/08 Wolf Creek Generating Station (2/2006) cc:

Jay Silberg, Esq. County Clerk Pillsbury Winthrop Shaw Pittman LLP Coffey County Courthouse 2300 N Street, NW 110 South 6th Street Washington, D.C. 20037 Burlington, KS 66839 Regional Administrator, Region IV Chief, Radiation and Asbestos Control U.S. Nuclear Regulatory Commission Section 611 Ryan Plaza Drive, Suite 400 Kansas Department of Health Arlington, TX 76011 and Environment Bureau of Air and Radiation Senior Resident Inspector 1000 SW Jackson, Suite 310 U.S. Nuclear Regulatory Commission Topeka, KS 66612-1366 P.O. Box 311 Burlington, KS 66839 Vice President Operations/Plant Manager Wolf Creek Nuclear Operating Corporation Chief Engineer, Utilities Division P.O. Box 411 Kansas Corporation Commission Burlington, KS 66839 1500 SW Arrowhead Road Topeka, KS 66604-4027 Supervisor Licensing Wolf Creek Nuclear Operating Corporation Office of the Governor P.O. Box 411 State of Kansas Burlington, KS 66839 Topeka, KS 66612 U.S. Nuclear Regulatory Commission Attorney General Resident Inspectors Office/Callaway Plant 120 S.W. 10th Avenue, 2nd Floor 8201 NRC Road Topeka, KS 66612-1597 Steedman, MO 65077-1032

STAFF EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RESULTS OF FOURTEENTH STEAM GENERATOR TUBE INSERVICE INSPECTION WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482

1.0 INTRODUCTION

By letters dated January 31 and March 19, 2007, and February 28, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML070430458, ML070860222, and ML080660359, respectively), Wolf Creek Nuclear Operating Corporation (the licensee) submitted information pertaining to the fourteenth steam generator (SG) tube inspection performed at Wolf Creek Generating Station (Wolf Creek) during the fifteenth refueling outage conducted in the fall of 2006 in accordance with the plants technical specifications (TS). The letter dated February 28, 2008, was in response to questions from the U.S. Nuclear Regulatory Commission (NRC) staff on its review of the letters dated January 31 and March 19, 2007.

The licensee has four Westinghouse Model F steam generators. There are 5626 thermally treated Alloy 600 tubes in each SG. The tubes have an outside diameter of 0.688 inches, a wall thickness of 0.040 inches, and 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 their SG tube inspections in the documents referenced above. In addition, the licensee described corrective actions (i.e.,

tube plugging or repair) taken in response to the inspection findings.

2.0 EVALUATION Based on its review of the reports submitted, the NRC staff has the following observations and comments:

• At the end of the fifteenth refueling outage, Wolf Creek was in the second sequential (90 effective full power months (EFPM)) inservice inspection period.

The SGs had operated 81.84 EFPM in this period.

• Cleaning of the secondary side of SGs A and D with an advanced scale conditioning agent (ASCA) was performed during refueling outage 15. In

addition, scale profiling was performed using eddy current data. The ASCA reduced the level of deposits in the SGs.

• A visual inspection revealed that the quatrefoil-shaped tube support holes were essentially open.

3.0 CONCLUSION

Based on a review of the information provided, the staff concludes that the licensee provided the information required by their TS. In addition, the 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: Emma Wong Date: March 20, 2008