ML050610566
| ML050610566 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 03/18/2005 |
| From: | John Nakoski NRC/NRR/DLPM/LPD2 |
| To: | Gordon Peterson Duke Energy Corp |
| SHea J, 415-1388, NRR/DLPM | |
| References | |
| TAC MC2386, TAC MC2387 | |
| Download: ML050610566 (7) | |
Text
March 18, 2005 Mr. G. R. Peterson Vice President McGuire Nuclear Station Duke Energy Corporation 12700 Hagers Ferry Road Huntersville, NC 28078-8985
SUBJECT:
MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 - REQUEST FOR RELIEF RE: PRESSURIZER SUPPORT SKIRT WELDS RR-03-05 (TAC NOS. MC2386 AND MC2387)
Dear Mr. Peterson:
By letter to the Nuclear Regulatory Commission (NRC) dated March 8, 2004, Duke Energy Corporation, the licensee for McGuire Nuclear Station (McGuire), Units 1 and 2, requested an alternative to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code), 1998 Edition through the 2000 Addenda, for Table IWB-2500-1, Examination Category B-K, Welded Attachments for Vessels, Piping, Pumps, and Valves.
The NRC staff has completed its review of the subject request for relief. As documented in the enclosed Safety Evaluation, the NRC staff concludes that compliance with the Code requirements would result in a hardship without a compensating increase in the level of quality and safety. Additionally your proposed alternative will provide reasonable assurance of the structural integrity of the subject components. Accordingly, the NRC staff authorizes the use of the alternative pursuant to 10 CFR 50.55a(a)(3)(ii) for the third 10-year inservice inspection interval. All other ASME Code,Section XI requirements for which relief has not been specifically requested remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
Sincerely,
/RA/
John A. Nakoski, Chief, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-369 and 50-370
Enclosure:
As stated cc w/encl: See next page
March 18, 2005 Mr. G. R. Peterson Vice President McGuire Nuclear Station Duke Energy Corporation 12700 Hagers Ferry Road Huntersville, NC 28078-8985
SUBJECT:
MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 - REQUEST FOR RELIEF RE: PRESSURIZER SUPPORT SKIRT WELDS RR-03-05 (TAC NOS. MC2386 AND MC2387)
Dear Mr. Peterson:
By letter to the Nuclear Regulatory Commission (NRC) dated March 8, 2004, Duke Energy Corporation, the licensee for McGuire Nuclear Station (McGuire), Units 1 and 2, requested an alternative to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code), 1998 Edition through the 2000 Addenda, for Table IWB-2500-1, Examination Category B-K, Welded Attachments for Vessels, Piping, Pumps, and Valves.
The NRC staff has completed its review of the subject request for relief. As documented in the enclosed Safety Evaluation, the NRC staff concludes that compliance with the Code requirements would result in a hardship without a compensating increase in the level of quality and safety, additionally your proposed alternative will provide reasonable assurance of the structural integrity of the subject components. Accordingly, the NRC staff authorizes the use of the alternative pursuant to 10 CFR 50.55a(a)(3)(ii) for the third 10-year inservice inspection interval. All other ASME Code,Section XI requirements for which relief has not been specifically requested remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
Sincerely,
/RA/
John A. Nakoski, Chief, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-369 and 50-370
Enclosure:
As stated cc w/encl: See next page DISTRIBUTION: PUBLIC PDII-1 R/F JShea SPeters CHawes JNakoski EHackett MMitchell TMcLellan THsia MErnstes, RII GHill (2)
ACRS OGC DLPM DPR ADAMS Accession Number: ML050610566 NRR-106 OFFICE PDII-1:PM PDII-1:LA (A)
DE/SC OGC PDII-1:SC NAME JShea CHawes MMitchell KKannler JNakoski DATE 3/7/05 3/4/05 2/9/05 3/17/05 3/18/05 OFFICIAL RECORD COPY
McGuire Nuclear Station cc:
Ms. Lisa F. Vaughn Duke Energy Corporation Mail Code - PB06E 422 South Church Street P.O. Box 1244 Charlotte, North Carolina 28201-1244 County Manager of Mecklenburg County 720 East Fourth Street Charlotte, North Carolina 28202 Mr. C. Jeffrey Thomas Regulatory Compliance Manager Duke Energy Corporation McGuire Nuclear Site 12700 Hagers Ferry Road Huntersville, North Carolina 28078 Anne Cottingham, Esquire Winston and Strawn 1400 L Street, NW Washington, D.C. 20005 Senior Resident Inspector c/o U.S. Nuclear Regulatory Commission 12700 Hagers Ferry Road Huntersville, North Carolina 28078 Dr. John M. Barry Mecklenburg County Department of Environmental Protection 700 N. Tryon Street Charlotte, North Carolina 28202 Mr. Peter R. Harden, IV VP-Customer Relations and Sales Westinghouse Electric Company 6000 Fairview Road, 12th Floor Charlotte, North Carolina 28210 Ms. Karen E. Long Assistant Attorney General North Carolina Department of Justice P.O. Box 629 Raleigh, North Carolina 27602 Mr. R. L. Gill, Jr.
Manager - Nuclear Regulatory Issues and Industry Affairs Duke Energy Corporation 526 South Church Street Mail Stop EC05P Charlotte, North Carolina 28202 NCEM REP Program Manager 4713 Mail Service Center Raleigh, North Carolina 27699-4713 Mr. Richard M. Fry, Director Division of Radiation Protection North Carolina Department of Environment, Health and Natural Resources 3825 Barrett Drive Raleigh, North Carolina 27609-7721 Mr. T. Richard Puryear Owners Group (NCEMC)
Duke Energy Corporation 4800 Concord Road York, South Carolina 29745 Henry Barron Group Vice President, Nuclear Generation and Chief Nuclear Officer P.O. Box 1006-EC07H Charlotte, NC 28201-1006
ENCLOSURE SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PRESSURIZER SUPPORT SKIRT WELD RR-03-005 DUKE ENERGY CORPORATION MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 DOCKET NOS. 50-369 AND 50-370
1.0 INTRODUCTION
By letter to the Nuclear Regulatory Commission (NRC) dated March 8, 2004, Duke Energy Corporation (Duke), the licensee for McGuire Nuclear Station (McGuire), Units 1 and 2, requested an alternative to the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code), 1998 Edition through the 2000 Addenda, for Table IWB-2500-1, Examination Category B-K, Welded Attachments for Vessels, Piping, Pumps, and Valves.
2.0 REGULATORY EVALUATION
2.1 Applicable Requirements The Inservice Inspection (ISI) of ASME Code, Class 1, 2, and 3 components shall be performed in accordance with Section XI, Rules for ISI of Nuclear Power Plant Components, of the ASME Code and applicable addenda as required by Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i). Section 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used when authorized by the NRC, if the licensee demonstrates that (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1, 2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the pre-service examination requirements, set forth in the ASME Code,Section XI, "Rules for ISI of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein. The applicable Code of record for the third 10-year inservice 1 Attachment 1 is included in the licensees letter dated March 8, 2004 (ML040760747) and is not included in this safety evaluation inspection for McGuire, Units 1 and 2 is the 1998 Edition through 2000 Addenda of the ASME Code,Section XI. The licensee was approved to use the 1998 Edition through 2000 Addenda for McGuire, Unit 1 in NRC Safety Evaluation dated November 17, 2004. The McGuire, Unit 1 third 10-year ISI interval began on December 1, 2001, and ends on November 30, 2011, and the McGuire, Unit 2 third 10-year ISI interval began on March 1, 2004, and ends on February 28, 2014.
3.0 TECHNICAL EVALUATION
3.1 Systems/Components For Which Relief Is Requested Pressurizer - Welded Attachment Unit Item No Weld ID No.
Description 1
B10.010.001 1PZR-SKIRT Pressurizer Support Skirt to Lower Head Weld 2
B10.010.001 2PZR-SKIRT Pressurizer Support Skirt to Lower Head Weld 3.2 Code Requirement The ASME Code,Section XI, 1998 Edition through the 2000 Addenda, Table IWB-2500-1 specifies the components and examination methods for Class 1 pressure retaining components.
Examination Category B-K, of Table IWB-2500-1 includes welded attachments for vessels, piping, pumps, and valves. Item No. B10.10, is the examination requirements for pressure vessels, welded attachments, which specifies surface exams for these welded components.
The specified surface exams are to be completed in accordance with figure No. IWB-2500-13, 14 or 15. The required figure for the components in question is IWB-2500-13 as modified by the final rulemaking regarding 10 CFR 50.55a that became effective on October 28, 2002.
Paragraph 50.55a(b)(2)(xxi)(C) identities a limitation on the code edition/addenda applicability for use of Table IWB-2500-1, Examination Category B-K, Item B10.10. It specifically states:
"... the 1995 Addenda must be applied when using the 1997 Addenda through the latest edition and addenda incorporated by reference in paragraph (b)(2) of this section.
3.3 Licensees Proposed Alternative Duke requests approval to use an alternative to ASME Code Section XI requirements. The licensee proposes to use the ultrasonic method for examination of the inside circumference weld surface C-D (Attachment 11). This inner weld surface will be scanned from the exterior of the skirt by a 30 degree shear wave from one axial direction covering 96 percent of the required examination volume; a 45 degree shear wave from the opposite axial direction covering 50 percent of the required examination volume; a 45 degree shear wave circumferential scan, clockwise and counter-clockwise, covering 76 percent of the required examination volume; and a straight beam longitudinal wave examination covering 76 percent of the examination volume.
These scans represent the estimated maximum obtainable examination coverage with the ultrasonic method. Duke will also perform the Code specified surface examination method on the outside circumference weld surface A-B (Attachment 11).
3.4 Basis for Use of Proposed Alternative Duke requests relief from the surface examination method required on surface C-D as shown on Attachment 1 of the licensee submittal. Surface C-D is not accessible for examination for the following reasons:
1.
The Pressurizer heater cables cause an interference and they must be disconnected to provide access. Previously this work caused termination joint and ceramic insulator damage that had to be repaired.
2.
The maximum clearance between the inside surface of the support skirt and the outside row of the heaters is 14 inches. This is insufficient clearance for performing the required surface examination.
3.
The inside of the support skirt is a high radiation area. Personnel performing the required examination could receive a significant dose. The general area dose rate is 400 mr/hr and the contact dose rates range from 1,000 to 3,000 mr/hr.
The ultrasonic method has been shown to be capable of detecting surface connected flaws in pressure vessel welds when a properly designed technique is used. The ultrasonic procedure and the basic calibration block will conform to the requirements of ASME Section XI, Appendix I, 1998 Edition through the 2000 Addenda.
3.5 Staff Evaluation The ASME Code 1998 Edition through the 2000 Addenda,Section XI, Table IWB-2500-1, Examination Category B-K, Welded Attachments for Vessels, Piping, Pumps, and Valves, Item No. B10.10, Pressure Vessels, Welded Attachments, Figure No. IWB-2500-13, requires a surface examination of the attachment weld length. This requirement was modified by the final rulemaking regarding 10 CFR 50.55a that became effective on October 28, 2002.
Paragraph 50.55a(b)(2)(xxi)(C) identities a limitation on the code edition/addenda applicability for use of Table IWB-2500-1, Examination Category B-K, Item B10.10. It specifically states: "...
the 1995 Addenda must be applied when using the 1997 Addenda through the latest edition and addenda incorporated by reference in paragraph (b)(2) of this section.
The 1997 Addenda through the latest edition and addenda of the ASME Code in reference in 10 CFR 50.55a(b)(2) permit performance of a single-side surface examination in place of surface examination from both sides of the weld, whereas the 1995 Addenda requires that the performance of a single-side volumetric examination of the weld of the inaccessible surface if surface examination from both sides of the weld is not performed. However, this alternative requirement only applies to Figure IWB-2500-14. The licensees Code required examination of the Pressurizer Support Skirt to Lower Head Weld is based on Figure IWB-2500-13 for which the Code does not provide for an alternative volumetric examination from one-side in lieu of the required two-side surface examination. Thus, the licensee requested relief from performing the Code required surface examination of the inner weld and proposed to perform a single-side volumetric examination of the subject weld.
2 Attachments 2 and 3 are sketches included in the licensees letter dated March 8, 2004 (ML040760747) and are not included in this safety evaluation As shown in the licensees sketch (Attachment 22) of the pressurizer heater cables, in order for the licensee to gain access to perform the Code required surface examinations the cables must be disconnected to provide access to examine the subject weld. Disconnecting the heater cables could cause damage to the termination joint and ceramic insulator. In addition, as shown in the licensees attached sketch (Attachment 32) of the support skirt and heater cables, there is only a maximum clearance of 14 inches between the inside surface of the support skirt and the outside row of the heaters. The distance of 14 inches does not allow the licensee enough clearance to perform the required Code examination. Furthermore, inside of the support skirt is a high radiation area with a general area dose rate of 400 mr/hr and with a contact dose rate range from 1,000 to 3,000 mr/hr. Therefore, the NRC staff determined that it would be a significant hardship without a compensating increase in quality and safety in order for the licensee to perform the Code required examinations.
As noted above, the licensee proposed to use as an alternative to the Code requirements an ultrasonic method to examine the inside circumference weld surface. The subject weld will be scanned from the exterior of the skirt with four different types of transducers from six directions (two of which are from opposing directions). The various scans provide shear wave coverages of 96 percent, 50 percent, 76 percent, and a straight beam longitudinal wave coverage of 76 percent of the examination volume. The licensee will also perform the Code required surface examination on the outside circumference weld surface of the Pressurizer Support Skirt to Lower Head Welds 1PZR-SKIRT and 2PZR-SKIRT. Therefore, the NRC staff determined that the coverage that will be obtained should detect if any significant patterns of degradation are present and provide reasonable assurance of structural integrity of the subject welds.
4.0 CONCLUSION
The NRC staff has reviewed the licensee's submittal and concludes that the Code examination coverage requirements are a significant hardship without a compensating increase in quality and safety for the subject components listed in Request for Relief No.03-005. Further, reasonable assurance of the structural integrity of the subject components will be provided by the examinations that will be performed. Therefore, pursuant to 10 CFR 50.55a(a)(3)(ii), the licensees proposed alternative is authorized for the third 10-year ISI interval at McGuire, Units 1 and 2. All other requirements of the ASME Code,Section XI for which relief has not been specifically requested remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: T. McLellan Date: March 18, 2005