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Summary Ultrasonic Examination Results of Completed Alloy 82/182 Weld Overlays
	ML071560504
Person / Time
Site:	Oconee
Issue date:	05/29/2007
From:	Brandi Hamilton; Duke Energy Carolinas, Duke Power Co
To:	; Document Control Desk, NRC/NRR/ADRO
References
	Download: ML071560504 (7)
	v • d • e

BRUCE H HAMILTON Vice President kEnergy@ Oconee Nuclear Station Duke Energy Corporation ONO1VP / 7800 Rochester Highway Seneca, SC 29672 864 885 3487 864 885 4208 fax bhhamilton@duke-energy.

com May 29, 2007 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

Subject:

Duke Power Company LLC, d/b/a Duke Energy Carolinas, LLC Oconee Nuclear Station, Unit 2 Docket No. 50-270 Summary Ultrasonic Examination Results of Completed Alloy 82/182 Weld Overlays By letters dated January 31, 2007 and February 22, 2007, Duke Power Company LLC, d/b/a Duke Energy Carolinas, LLC (Duke)committed to a mitigation schedule regarding Alloy 82/182 butt welds on Pressurizer piping. The NRC Confirmatory Action Letter (CAL) of March 27, 2007 regarding Alloy 82/182 butt welds requires a report within 60 days of unit restart of any mitigative actions taken on the subject welds.In order to support these mitigative actions, on March 12, 2007 Duke submitted Relief Request 07-ON-001 pursuant to 10 CFR 50.55a(a)

(3) (i)for approval to use alternatives to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI Inservice Inspection (ISI) alternative requirements for the Oconee Nuclear Station, Units 2 and 3 to support application of full structural weld overlays on various pressurizer nozzle to flange, nozzle-to-safe end, and surge line welds. NRC verbally approved this request on May 17, 2007. In our request we committed to providing a report summarizing the results of the ultrasonic (UT) examinations of the weld overlay within 14 days of completion of the UT examinations.

This letter is to.inform you of the completion of the mitigative repairs for Unit 2 as listed on Enclosure 3 of our January 31, 2007 letter. These actions were completed during 2E0C22 refueling outage and complete the actions related to Unit 2 to www. duke-energy.

corn U. S. Nuclear Regulatory Commission Page 2 May 29, 2007 satisfy the CAL. Enhanced leakage detection requirements committed to in our February 22, 2007 letter are no longer required on Unit 2 due to the completion of mitigation of the subject welds.Attachment 1 provides a report summarizing the results of the Unit 2 UT examinations of the weld overlay (completed May 15, 2007), per the commitment contained in the relief request. This letter and attachment provide the required responses for the relief request commitment and the CAL.Our staff is available to meet with the NRC to discu ss any of the information contained in this letter. If there are any questions, please contact Randy Todd at (864) 885-3418.Very truly yours, B.H. Hamilton, Vice President Oconee Nuclear Site Attachment U. S. Nuclear Regulatory Commission May 29, 2007 cc: Mr. L. N. Olshan, Project Manager Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-14 H25 Washington, D.C. 20555 Dr. W. D. Travers, Regional Administrator U.S. Nuclear Regulatory Commission

-Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. D. W. Rich Senior Resident Inspector Oconee Nuclear Station Mr. Henry Porter, Director Division of Radioactive Waste Management Bureau of Land and Waste Management Department of Health & Environmental Control 2600 Bull Street Columbia, S.C. 29201 U. S. Nuclear Regulatory Commission May 29, 2007 bxc w/att: R. L. Gill, Jr.T. J. Coleman D. W. Peltola P. A. Wells R. K. Rhyne D. H. Llewellyn C. R. Frye J. M. Shupping V. B. Dixon B. W. Carney, Jr.R. P. Todd L. C. Keith G. L. Brouette (ANII)J. J. Mc Ardle III J. E. Smith ISI Relief Request File NRIA File/ELL EC050 Document Control Attachment Summary of Ultrasonic Examinations of Preemptive Weld Overlays for Surge, Hot Leg Surge, Spray, and Safety/Relief Valve Nozzle-to-Safe-End Welds at Oconee Nuclear Station, Unit 2 Attachment to SIR-07-164-NPS, Rev. 1 1 of 3 Structural Integrity Associates, Inc.

Ultrasonic Examination Procedure SI-UT-126 Revision 3, Procedure for the Phased Array Ultrasonic Examination of Weld Overlaid Similar and Dissimilar Metal Welds, was used during the examinations.

This procedure, and the examiners who applied the procedure, are qualified through the PDI Program at the EPRI NDE Center.Pressurizer Surge Nozzle Weld Overlay Examination Component Identification:

2-PZR-WP23 Examination Date: 05/15/07 Examination Time: 02:00 -03:15 Weld Overlay Regions: Overlay, Weld and Base Material (Outer 25%) Dissimilar Metal Weld Axial Examination Angles: 0' through 830 (Except Zone 1 WOL axial examination angles 00 through 81') -Circumferential Examination Angles: 0' through 650 Examination Summary: No suspected flaw indications were observed during the examinations.

The examination gain was adjusted to maintain the procedure-specified baseline noise level from 5% to 20% of full screen height. The lower range of examination angles detected responses from the inside surface of the component which were useful for monitoring search unit contact/coupling effectiveness during the examination.