ML13098A229
| ML13098A229 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 04/08/2013 |
| From: | Boska J Plant Licensing Branch II |
| To: | Robertson J Duke Energy Carolinas |
| Boska J | |
| References | |
| TAC MF0515 | |
| Download: ML13098A229 (3) | |
Text
From:
Boska, John Sent:
Monday, April 08, 2013 11:52 AM To:
Robertson, Jeffrey Cc:
Vu, Phong T
Subject:
McGuire Nuclear Station Unit 1, Request for Additional Information, TAC MF0515, RR12-MN-004, Section 10 Importance:
High On November 29, 2012, ADAMS Accession No. ML12355A149, Section 10, Duke Energy Carolinas, LLC (Duke), submitted an application for a proposed relief request for McGuire Nuclear Station, Unit 1.
The Nuclear Regulatory Commission staff is reviewing the submittal and has determined that additional information is needed to complete its review of Section 10. The specific questions are found below. Please provide a response to this request for additional information within 30 days of the date of this email.
John Boska Oconee Project Manager, NRR/DORL Catawba/McGuire Project Manager (Acting)
U.S. Nuclear Regulatory Commission 301-415-2901 email: john.boska@nrc.gov REQUEST FOR ADDITIONAL INFORMATION ON THE THIRD 10-YEAR INTERVAL INSERVICE INSPECTION REQUEST FOR RELIEF 12-MN-004, SECTION 10 DUKE ENERGY CAROLINAS, LLC.
MCGUIRE NUCLEAR STATION, UNIT 1 DOCKET NUMBER: 50-369 (TAC NUMBER MF0515) 1.0 SCOPE By letter dated November 29, 2012 (Agencywide Documents Access and Management System (ADAMS) at Accession Number ML12355A149), Duke Energy Carolinas, LLC.
(the licensee) requested relief from the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (B&PV Code)Section XI, for McGuire Nuclear Station, Unit 1 (MNS, Unit 1). The Request for Relief No. 12-MN-004, Section 10, covers MNS, Unit 1 Head Ring to Head Cap, Weld # 1RPV-446B, Summary Number M1.B1.21.0001 where the licensee was not able to achieve essentially 100% inspection coverage due to materials and geometrical limitations.
2.0 REGULATORY EVALUATION
Pursuant to Title 10 of the Code of Federal Regulations (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 preservice examination requirements, set forth in the ASME Code,Section XI 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, which was incorporated by reference in 10 CFR 50.55a(b) 12 months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.
10 CFR 50.55a(g)(5)(iii), states, in part that, licensees may determine that conformance with certain code requirements is impractical and that the licensee shall notify the Commission and submit information in support of the determination. Determination of impracticality in accordance with this section must be based on the demonstrated limitations experienced when attempting to comply with the code requirements during the inservice inspection interval for which the request is being submitted. Requests for relief made in accordance with this section must be submitted to the NRC no later than 12 months after the expiration of the initial 120-month inspection interval or subsequent 120-month inspection interval for which relief is sought.
10 CFR 50.55a(g)(6)(i), states that the Commission will evaluate determinations under paragraph (g)(5) of this section that code requirements are impractical. The Commission may grant such relief and may impose such alternative requirements as it determines is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.
The licensee has requested relief from ASME Code requirements pursuant to 10 CFR 50.55a(g)(6)(i). The ASME Code of record for MNS, Unit 1 third 10-year interval inservice inspection program, which started on December 01, 2001 and ended on December 01, 2011, was the 1998 Edition, through the 2000 Addenda, of Section XI of the ASME Boiler and Pressure Vessel Code. Based on the above, and subject to the following technical evaluation, the NRC staff finds that regulatory authority exists for the licensee to request and the Commission to grant the relief requested by the licensee.
3.0 REQUEST FOR ADDITIONAL INFORMATION For Request for Relief No. 12-MN-004, Section 10, the licensee requested relief from the ASME Code-required volumetric examination MNS, Unit 1 Head Ring-to-Head Cap, Weld # 1RPV-446B, Summary Number M1.B1.21.0001 of the Reactor Coolant System.
The US Nuclear Regulatory Commission (NRC) staff recognizes that licensees use their own various nomenclatures in naming the components of their particular plant. Based on the licensees provided drawings in Attachment B of the relief request, the NRC staff interprets that for the Reactor Pressure Vessel (RPV) Head Ring-to-Head Cap Weld the licensee means its seeking relief for the examination of the weld commonly known in the industry as the RPV Head-to-Flange Weld. The licensee listed its RPV Head Ring-to-Head Cap component under ASME Code, Category B-A, Item B1.21 which is described under the ASME Code, Table IWB-2500-1 as Head Welds Circumferential and Meridional.
Industry generally recognizes these welds as bottom Reactor Pressure Vessel Dollar Plate Circumferential Welds and the ASME Code requirements are different.
The RPV Head-to-Flange comes under ASME Code Category B-A, Item B1.40 which requires Figure IWB-2500-5, Examination Volume A-B-C-D Essentially 100% volumetric
and surface examination coverage of the weld length. Essentially 100 percent, as clarified by ASME Code Case N-460 Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI, Division 1, is greater than 90 percent coverage of the examination volume, or surface area, as applicable. ASME Code Case N-460, has been approved for use by the NRC in Regulatory Guide G 1.147, Revision 16 Inservice Inspection Code Case Acceptability.
For the Bottom Reactor Pressure Vessel Dollar Plate Circumferential and Meridional Welds the ASME Code,Section XI, Table IWB-2500-1, Examination Category B-A, Item Number B1.21, Figure IWB-2500-3, Examination Volume A-B-C-D requires essentially 100% volume coverage of the accessible weld length and no surface examination.
For the Bottom Reactor Pressure Vessel Dollar Plate Circumferential and Meridional Welds, the ASME Code Committees recognize the limitations of examining these welds and specifically stated in this particular ASME Code requirement to examine the accessible length of the welds. If a licensee stated that it did examine the accessible length of the subject welds they met the ASME Code requirements and do not require relief from the ASME Code requirements.
Provide a clarification of the component in which the licensee is seeking relief and state if the licensee met the ASME Code examination requirements including the surface examination, if required.