NOC-AE-10002600, Request for Relief from ASME Section XI Requirements for Ultrasonic Examination of Reactor Pressure Vessel Shell-to-Flange Welds (RR-ENG-3-05)

Request for Relief from ASME Section XI Requirements for Ultrasonic Examination of Reactor Pressure Vessel Shell-to-Flange Welds (RR-ENG-3-05)

ML102950166
Person / Time
Site:	South Texas
Issue date:	10/18/2010
From:	Ruvalcaba M South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-10002600, RR-ENG-3-05
Download: ML102950166 (4)

Text

Nuclear Operating Company South Texas Pro/ectElectric Generating Station PO. Box 28.9 Wadsworth, Texas 77483 ,

October 18, 2010 NOC-AE-10002600 File No.: G25 10 CFR 50.55a U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2746 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, 50-499 Request for Relief from ASME Section Xl Requirements for Ultrasonic Examination of Reactor Pressure Vessel Shell-to-Flange Welds (RR-ENG-3-05)

In accordance with the provisions of 10 CFR 50.55a(a)(3)(i), STP Nuclear Operating Company (STPNOC) proposes an alternative to the requirements of ASME Section Xl applicable to ultrasonic examination of the Reactor Pressure Vessel (RPV) shell-to-flange weld.

The South Texas Project (STP) Code of Record for the third inspection interval is ASME Section Xl 2004 Edition No Addenda. IWA-2232 of Section XI requires that ultrasonic (UT) examinations be conducted in accordance with Section Xl Appendix I. Appendix I, Article 1-2110(b) requires that UT examination of the RPV shell-to-flange weld be performed in accordance with ASME Section V, Article 4 which is qualified using a prescriptive-based process. STPNOC proposes an alternative using the performance-based methods of ASME Section Xl, 2001 Edition (no Addenda), Appendix VIII Supplements 4 and 6, as modified by 10 CFR 50.55a(b)(2)(xxiv). The proposed alternative will provide an acceptable level of quality and safety.

STPNOC requests NRC approval of this alternate approach by October 30, 2011, to support scheduling activities to be performed later in the inspection interval.

There are no commitments included with this request.

If there are any questions, please contact either Mr. P. L. Walker at (361) 972-8392 or me at (361) 972-7904.

Marco Ruv Ilcaba Manager, Testing and Programs Engineering PLW

Attachment:

Request for Relief from ASME Section Xl Requirements for Ultrasonic Examination of Reactor Pressure Vessel Shell-to-Flange Welds (RR-ENG-3-05)

STI: 32744693 4ti-DO O

.rd

NOC-AE-10002600 Page 2 of 2 cc:

(paper copy) (electronic copy)

Regional Administrator, Region IV John Ragan U. S. Nuclear Regulatory Commission Catherine Callaway 612 East Lamar Blvd, Suite 400 Jim von Suskil Arlington, Texas 76011-8064 NRG South Texas LP Mohan C. Thadani A. H. Gutterman, Esquire Senior Project Manager Morgan, Lewis & Bockius LLP U.S. Nuclear Regulatory Commission One White Flint North (MS 8 B1A) 11555 Rockville Pike Mohan C. Thadani Rockville, MD 20852 U. S. Nuclear Regulatory Commission Senior Resident Inspector Richard Pena U. S. Nuclear Regulatory Commission E. Alarcon P. 0. Box 289, Mail Code: MN1 16 Kevin Polio Wadsworth, TX 77483 City Public Service C. M. Canady C. Mele City of Austin City of Austin Electric Utility Department 721 Barton Springs Road Peter Nemeth Austin, TX 78704 Crain Caton & James, P.C.

Richard A. Ratliff Texas Department of State Health Services Alice Rogers Texas Department of State Health Services

Attachment NOC-AE-1 0002600 Page 1 of 2 SOUTH TEXAS PROJECT UNITS I AND 2 REQUEST FOR RELIEF FROM ASME SECTION XI REQUIREMENTS FOR ULTRASONIC EXAMINATION OF REACTOR PRESSURE VESSEL SHELL-TO-FLANGE WELDS (RR-ENG-3-05)

1. Reference Code for Third Inservice Inspection Interval 0 ASME Section XI, 2004 Edition (No Addenda)

2. Components Affected (a) Component: Reactor Pressure Vessel (RPV)

(b)

Description:

Shell-to-flange weld RPV1-101-121 (c) Class: ASME Code Class 1

3. Applicable Code Requirement

The South Texas Project (STP) Code of Record for the third inspection interval is ASME Section Xl 2004 Edition No Addenda. IWA-2232 of Section Xl requires that ultrasonic (UT) examinations be conducted in accordance with Section XI Appendix I. Appendix I, Article 1-2110(b) requires that UT examination of the RPV shell-to-flange weld be performed in accordance with ASME Section V, Article 4 which is qualified using a prescriptive-based inspection process.

STPNOC proposes an alternative to Appendix I Article 1-2110(b) 'for RPV shell-to-flange weld UT examinations.

4. Basis for Relief from Code Requirements The RPV shell-to-flange weld is the only circumferential shell weld in the RPV not examined according to ASME Section Xl, Appendix VIII, Supplements 4 and 6 UT techniques [Article 1-2110(a)].

Procedures, equipment, and personnel qualified by the Appendix VIII Performance Demonstration Initiative (PDI) Programs for Supplements 4 and 6 have demonstrated a high probability of detecting flaws, and are generally considered superior to those qualified under Section V, Article 4 criteria.

5. Proposed Alternative The RPV shell-to-flange weld will be examined in accordance with the performance-based methods of ASME Section XI, 2001 Edition (no Addenda), Appendix VIII, Supplements 4 and 6, as modified by 10 CFR 50.55a(b)(2)(xxiv).

Attachment NOC-AE-1 0002600 Page 2 of 2

6. Justification for Granting Relief ASME Section Xl, 2004 Edition 2005 Addenda, Appendix I, Article 1-2600(a) states that for components to which Appendix VIII is not applicable, examination procedures, personnel, and equipment qualified in accordance with Appendix VIII may be applied provided such components, materials, sizes, and shapes are within the scope of the qualified examination procedure.

Industry experience has shown that the Appendix VIII PDI approach for UT examinations equals or surpasses the UT examination techniques of the ASME Code,Section V, Article 4 for detection and characterization of flaws in reactor pressure vessels. The procedure requires the examiner to evaluate all indications determined to be flaws regardless of their amplitude.

The proposed qualification approach is more conservative. Therefore, use of the proposed alternative will provide an acceptable level of quality and safety.

7. Implementation Schedule:

The alternative RPV shell-to-flange weld examination requirements as described above are to be applied in both the Unit 1 and Unit 2 third 10-year inservice inspection intervals. The intervals end September 25, 2020, for Unit 1, and October 19, 2020, for Unit 2. STPNOC requests NRC approval of this alternate approach by October 30, 2011, to support scheduling activities to be performed later in the inspection interval.