ML063530337

Donald C. Cook Nuclear Plant, Unit 2, Proposed Alternative to the American Society of Mechanical Engineers Code, Section Xi, Supplemental Information

ML063530337
Person / Time
Site:	Cook
Issue date:	12/07/2006
From:	Jensen J N Indiana Michigan Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
AEP:NRC:6055-21, TAC MC9305
Download: ML063530337 (6)

Text

2 INDIANA MICHIGAN POWER'A unit of American Electric Power December 7, 2006 Indiana Michigan Power Cook Nuclear Plant One Cook Place Bridgman, MI 49106 AE~com AEP:NRC:6055-21 10 CFR 50.55a Docket No.: 50-316 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop O-PI-17 Washington, DC 20555-0001 Donald C. Cook Nuclear Plant Unit 2 PROPOSED ALTERNATIVE TO THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS CODE, SECTION XI SUPPLEMENTAL INFORMATION (TAC No. MC9305)

References:

1.Letter from Joseph N. Jensen, Indiana Michigan Power Company (I&M), to Nuclear Regulatory Commission (NRC) Document Control Desk,"Donald C. Cook Nuclear Plant Unit 2, Proposed Alternative to the American Society of Mechanical Engineers Code,Section XI Repair Requirements, Request for Additional Information," AEP:NRC:6055, Accession Number ML060620063, dated March 1, 2006.2. Electronic Transmission from Peter. S. Tam, NRC, to Michael K. Scarpello, I&M,"D. C. Cook -Information Needed to Close Review on Preemptive Weld Overlay (TAC MC9305)," Accession Number ML063190130, dated November 14, 2006.In Reference 1, Indiana Michigan Power Company (I&M) requested relief from the provisions of the American Society of Mechanical Engineers (ASME) Code,Section XI in order to apply preemptive weld overlays on the Unit 2 pressurizer piping dissimilar metal welds. As part of the relief request, I&M proposed performing an ultrasonic examination (UT) of an area that extended beyond the weld overlay by 1.5 times the wall thickness of the pressurizer nozzle (1.5T band) to the extent practical.

This proposal was made because the configuration of the area covered by the weld overlays prevented a 100 percent UT of the 1.5T band required by Code Case N-638-1. In a March 21, 2006, telephone conversation, I&M informed the Nuclear Regulatory Commission (NRC) that I&M was having difficulty in obtaining a calibration block that met the requirements of ASME SA-388,"Recommended Practice for Ultrasonic Testing and Inspection of Heavy Steel Forgings," and I&M agreed to perform a "best, effort" examination.

In Reference 2, the NRC requested additional information regarding the calibration block used during the UT examination of 1.ST bands. The requested information is provided in the attachmient to this letter.04-7 U. S. Nuclear Regulatory Comniission Page 2 AEP:NRC:6055-21 This letter contaihs no new conmitments.

Should you have any questions, please contact Ms. Susan D. Simpson, Regulatory Affairs Manager, at (269) 466-2428.Sincerely, Site Support Services Vice President RV/rdw Attachment c: R. Aben -Department of Labor and Economic Growth J. L. Caldwell'-

NRC Region III K. D. Curry -AEP Ft. Wayne J. T. King- MPSC MDEQ -WHMD/RPMWS NRC Resident Inspector P.S. Tam- NRC Washington, DC Attachment to AEP:NRC:6055-21 Preemptive Weld Overlay Ultrasonic Examinations Supplemental Information In Reference 1, indiana Michigan Power Company (I&M) requested relief from the provisions of the American Society of Mechanical Engineers (ASME) Code,Section XI in order to apply preemptive weld overlays on the Unit 2 pressurizer piping dissimilar metal welds. As part of the relief request, I&M proposed performing an ultrasonic examination (UT) of an area that extended beyond the weld overlay by 1.5 times the wall thickness of the pressurizer nozzle (1.5T band) to the extent practical.

This proposal was made because the configuration of the area covered by the weld overlays prevented a 100 percent UT of the 1.5T band required by Code Case N-638-1. In a March 21, 2006, telephone conversation, I&M inforrmed the Nuclear Regulatory Commission (NRC) that I&M was having difficulty in obtaining a calibration block that met the requirements of ASME SA-388, "Reconmmended Practice for Ultrasonic Testing and Inspection of Heavy Steel Forgings," and I&M agreed to perform a "best effort" examination.

In)Reference 2, the NRC requested additional information regarding the calibration block used during the UT examination of 1.5T bands. The following provides the requested information.

NRC Request Provide "a written suimnary of the procedure used to generate the acoustic comparison results[between the calibration block material and the pressurizer nozzle material]

listed in the table that was provided to the NRC on August 31, 2006 [Table 1 of this attachment], and a justification that the results satisfy the requirements of [ASME] SA-388." I&M Response The Unit 2 pressurizer material is ASME SA-508. The calibration block used to perform the UT of the 1.5T band was fabricated from ASME SA-216 material.A comparison was made between calibration blocks fabricated of ASME SA-216 material (calibration block MP-20) and ASME SA-508 material (calibration block RV-3). Both calibration blocks contained a 0.5 thickness (0.5T) side-drilled hole (SDH) and a 0.75T SDH.The following describes the comparison process.Zero-Degree Transducer The zero degree transducer instrumentation was adjusted to obtain a signal amplitude equal to 80 percent (%) of full screen for the MP-20, 0.5T SDH, and the response of the MP-20, 0.75T SDH obtained.The MP-20 gain setting required to obtain an 80% of full screen response was 26 decibels (dB). The response from the 0.75T SDH was 50% of full screen at a 26 dB gain setting.

Attachment to AEP:NRC:6055-21 Page 2 The responses of RV-3 signal amplitudes at a 26 dB gain setting were obtained.

These were 70% of full screen for the 0.5T SDH and 25% of full screen for the 0.75T SDH.Forty Five-Degree Transducer The forty five-degree transducer instrumnentation was adjusted to obtain a signal amplitude equal to 80% of full screen for both the MP-20, 0.5T SDH and the RV-3, 0.5T SDH. The responses of the 0.75T SDHs were then obtained.The MP-20, 0.5T SDH gain setting for a signal amplitude equal to 80% of full screen was 50 dB. The.0.75T signal amnplitude at a 50.dB gain setting was 36% of full screen.The RV-3, 0.ST SDH gain setting for a signal amplitude equal to 80% of full screen was 44 dB. The 0.75T SDH signal amplitude at a gain setting 44 dB was 50% of full screen.Sixty-Degree Transducer The sixty-degree transducer instrumentation was adjusted to obtain a signal amplitude equal to 80% of full screen for both MP-20, 0.5T SDH and RV-3, 0.5T SDH. The responses of the 0.75T SDHs were then obtained.The MP-20, 0.5T SDH gain setting for a signal amplitude equal to 80% of full screen was 55 dB. The 0.75T SDH signal amplitude at a gainmsetting of 55 dB was 50% of full screen.The RV-3 gain setting to obtain a signal amplitude equal to 80% of full screen was 53 dB. The 0.75 T SDH signal amplitude at a gain setting of 53 dB was 58% of full screen.The calibration requirements of ASME SA-388 require that the calibration standard have the same nominal composition, heat treatment and thickness as the forging that it represents.

In the case of I&M's application, the calibration block used for the examination was fabricated from a different material than the pressurizer nozzle forging. However, the data obtained from UT scans of blocks fabricated fr-om ASME SA-216 material (the calibration block material) and from ASME SA-508 material (the nozzle forging material) are similar. Based on the above, the materials are considered acoustically similar for the purpose of the examinations performed.

It is I&M's opinion that an examination performed on ASME SA-508 using a calibration developed from ASME SA-216 material is more conservative than an examination performed using a calibration developed from ASME SA-508 material.

Attachmient to AEP:NRC:6055-21 Page 3

References:

1. Letter from Joseph N. Jensen, I&M, to NRC Document Control Desk,"Donald C. Cook Nuclear Plant Unit 2, Proposed Alternative to .the American Society of Mechanical Engineers Code,Section XI Repair Requirements, Request for Additional Information," AEP:NRC:6055, Accession Number ML060620063, dated March 1, 2006.2. Electronic Transmission from Peter S. Tam, NRC, to Michael K. Scarpello, I&M, "D. C. Cook -Information Needed to Close Review on Preemptive Weld Overlay (TAC MC9305), Accession Number ML063190130, dated November 14, 2006.

Attachment to AEP:NRC:6055-21 Page 4 TABLE 1 ULTRASONIC COMPARISON BETWEEN SA-216 and SA-508 U.)I Z)Ut1 (2.5 inches (")Deep)U '6dB 26dB/ Uo i/dB 26dB O 2.30 O0 2.38 0 Degree 0.75T SDH 50% @ 25%@(3.375" Deep) 00 3.55 26dB 00 3.70 26dB 45 Degree 0.5T SDH 80% @ 80% @(2.5" Deep) 450 3.30 50dB 45' 3.50 44dB 45 Degree 0.75T SDH 36%@ 50%@(3.375" Deep) 450 5.30 50dB 450 5.40 44dB 60 Degree 0.5T SDH 80% @ 80% @(2.5" Deep) 600 4.80 55dB 60" 5.60 53dB 60 Degree 0.75T SDH 50% @ 58%@(3.375" Deep) 60" 7.20 55dB 600 7.60 53dB Notes: 1. The selection of reflectors and transducer angles for this comparison are similar to those used for the examination of the 1.5T band.2. Based on the above, the materials are considered acoustically similar for the purpose of the examinations performed and no further examination is required.