L-06-042, Proposed Alternative to American Society of Mechanical Engineers Code Section XI Examination Requirements

Proposed Alternative to American Society of Mechanical Engineers Code Section XI Examination Requirements

ML061020308
Person / Time
Site:	Beaver Valley
Issue date:	04/07/2006
From:	Lash J FirstEnergy Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-06-042
Download: ML061020308 (5)

Text

FENOC FrstEnergy Nuclear Operating Company James H. Lash 724-682-5234 Site Vice President Fax: 724-643-8069 April 7, 2006 L-06-042 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001

Subject:

Beaver Valley Power Station, Unit Nos. 1 and 2 BVPS-1 Docket No. 50-334, License No. DPR-66 BVPS-2 Docket No. 50-412, License No. NPF-73 Proposed Alternative to American Society of Mechanical Engineers Code Section XI Examination Requirements (Request No. BV3-RV-1)

Pursuant to 10 CFR 50.55a(a)(3)(i), FirstEnergy Nuclear Operating Company (FENOC) hereby requests NRC approval to use an alternative remote mechanized examination technique for reactor vessel shell-to-flange welds during the third ten-year inservice inspection interval for Beaver Valley Power Station (BVPS) Unit No. 1 and second ten-year inservice inspection interval for BVPS Unit No. 2. The details of the 10 CFR 50.55a request are enclosed.

FEN0CE requests approval by September 2006 to support the BVPS Unit No. 2 maintenance and refueling outage, scheduled for early October 2006.

No new regulatory commitments are contained in this submittal. If there are any questions concerning this matter, please contact Mr. Gregory A. Dunn, Manager, Fleet Licensing at (330) 315-7243.

Sincerely, s H. Lash j 4O°-V7

Beaver Valley Power Station, Unit Nos. 1 and 2 Proposed Alternative to ASME Code Section XI Examination Requirements (Request No. BV3-RV-1)

L-06-(42 Page 2

Enclosure:

10 CFR 50.55a Request No. BV3-RV Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(i)

C: Mr. T. G. Colburn, NRR Senior Project Manager Mr. P. C. Cataldo, NRC Senior Resident Inspector MIr. S. J. Collins, NRC Region I Administrator Mr. D. A. Allard, Director BRP/DEP Mr. L. E. Ryan (BRP/DEP)

Enclosure to Letter L-06-042 10 CFR 50.55a Request Number BV3-RV-1, Revision 0 Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(i)

--Alternative Provides Acceptable Level of Quality and Safety--

1.0 ASME CODE COMPONENTS AFFECTED Reactor Vessel Shell-to-Flange Weld (RC-R-1-C-1 at Beaver Valley Power Station [BVPS] Unit No. 1 and 2RCS-REV21-C-lB at BVPS Unit No. 2) 2.0 APPLICABLE CODE EDITION AND ADDENDA ASME Section XI, 1989 Edition, no Addenda.

3.0 APPLICABLE CODE REQUIREMENTS Relief i; requested from using the techniques of Section V, Article 4, as supplemented by Section XI, Appendix I, and augmented by Regulatory Guide (RG) 1.150, Revision 1, when performriing volumetric examination of the reactor vessel shell-to-flange weld.

4.0 REASON FOR REQUEST The prescriptive, amplitude-based ultrasonic examination techniques of Section V, Article 4, supplemented by Appendix I, and augmented by RG 1.150, Revision 1 (hereafter referred to as Article 4), are technically inferior to the performance-based techniques specified in the 1995 Edition with 1996 Addenda of Section XI, Appendix VIII, Supplements 4 and 6, as modified by 10 CFR 50.55a(b)(2)(xv), and demonstrated through the Electric Power Research Institute (EPRI) Performance Demonstration Initiative (PDI) Program (Appendix VIII). The performance-based techniques of Appendix VIII are required for all other reactor vessel shell weld examinations, having replaced the Article 4 techniques.

Radiation exposure will be reduced since change out of examination devices on the inspection robot will not be necessary to perform the shell-to-flange weld examination. Additionally, the performance-based techniques of Appendix VIII offer several performance enhancements over the prescriptive amplitude-based techniques, as discussed below.

a. Increased sensitivity to flaws: The Appendix VIII procedure is more sensitive to flaws because the examination sensitivity level compares to an ASME distance amplitude correction (DAC) level of 5 to 10 percent, the highest practical level for ultrasonic testing. Examinations in accordance with Article 4 are conducted at 50 percent DAC for Ihe outer 80 percent of wall thickness and 20 percent DAC for the inner 20 percent of

'vall thickness. The Appendix VIII procedure requires all signals interpreted by the analyst as flaws to be measured and assessed in accordance with the applicable

Enclosure to Letter L-06-042 Request No. BV3-RV-1 Page 2 acceptance criteria, regardless of amplitude, recognizing that some flaws can exhibit a low amplitude response depending on orientation. The Article 4 techniques traditionally have a flaw response cut-off point of 20 percent DAC.

b. Demonstrated flaw measurement capability using amplitude-independent sizing techniques: The procedure for the proposed shell-to-flange weld examination has been demonstrated in accordance with ASME Section XI, Appendix VIII, Supplements 4 and 6, to the EPRI PDI.

The proposed procedure complies with ASME Code,Section XI, 1995 Edition with 1996 Addenda, as modified by 10 CFR 50.55a. The procedure has been qualified by time-based sizing techniques such as tip diffraction, rather than the amplitude-based ASME Section V techniques that have been proven inaccurate.

c. Compatibility of Appendix VIII examination technique with BVPS Unit Nos. 1 and 2 shell-to-flange weld geometry and previous examination history: The proposed Appendix VIII shell weld examination procedure will use the 45-degree beam angle in four orthogonal directions applied to the weld and volume by various transducer types, each covering a specified depth range. The increment size will be 0.5 inches and examination will be conducted to the maximum extent practical. When these examinations are combined with the manual examination performed from the flange seal surface, the coverage is expected to exceed 90 percent.

The previous remote mechanized examination of the shell-to-flange weld was conducted at BVPS Unit Nos. 1 and 2 in 1996. At that time 45, 60 and 70-degreee exam angles wvere used. Results were acquired and analyzed using an automated ultrasonic exam system with no indication found exceeding the allowable limits of Section XI. Data archival from the previous examination is available for comparison purposes should the need arise.

5.0 PROPOSED ALTERNATIVE AND BASIS FOR USE FENOC proposes using qualified personnel and procedures for remote mechanized examination in accordance with the 1995 Edition with 1996 Addenda of the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6, as modified by 10 CFR 50.55a(b)(2)(xv), and demonstrated by the EPRI PDI Program, for the reactor vessel shell-to-flange weld in lieu of volumetric examination in accordance with Article 4 of Section V, as supplemented by Appendix I of Section XI, and augmented by RG 1.150, Revision 1. These examinations will be conducted to the maximum extent practical and are subject to third party review by the Authorized Nuclear Inservice Inspector.

The BVPS Unit Nos. 1 and 2 reactor vessel upper shell courses immediately adjoining the flange to vessel welds are approximately 8.5 inches and 9.25 inches thick, respectively. The essential variable of the vendor procedure used to meet ASME Section XI, Appendix VIII requirements for Supplements 4 and 6, PDI-ISI-254, Revision 7, qualifies it for detection and length/depth

Enclosure to Letter L-06-042 Reques;t No. BV3-RV-1 Page 3 sizing of ferritic material with a nominal thickness of 0.0 to 12.30 inches. This procedure is qualified for single-sided examination, which indicates that it has been demonstrated to be capable of detecting and length sizing flaws on either side of the weld when examining from one side of the weld. This capability alone warrants the selection of this procedure over the prescriptive methods of non-Appendix VIII procedures. When combined with the examination that this; weld received from the flange side of the weld, this method is superior to the method prescribed by Section V, Article 4. Note also that this procedure is qualified without reservation to examine the intersecting longitudinal welds of the same (upper) shell course. BVPS Unit No. 2 contains longitudinal welds in this shell course; BVPS Unit No. I does not.

Use of ultrasonic test procedures and personnel qualified to the 1995 Edition with 1996 Addenda of Section XI of the ASME Code, Appendix VIII, Supplements 4 and 6, as modified by 10 CFP. 50.55a(b)(2)(xv) by demonstration through the EPRI PDI Program for the reactor vessel shell-to-flange weld provides equivalent or better examination results than those realized from ASME Section V requirements and RG 1.150 recommendations. Therefore, the alternative provides an acceptable level of quality and safety. In accordance with 10 CRF 50.55a(a)(3)(i),

FENOC requests approval of the proposed alternative.

6.0 DURATION OF THE PROPOSED ALTERNATIVE The proposed alternative is requested for the remainder of the third 10-Year Inservice Inspection Interval at BVPS Unit No. 1 and the second 10-Year Inservice Inspection Interval at BVPS Unit No. 2.

7.0 PRECEDENT The N1R.C granted the proposed alternative on October 26, 2005 in response to a similar request from Pacific Gas and Electric Company. Reference to the NRC letter authorizing the alternative is provided below.

Diablo Canyon Power Plant, Unit Nos. 1 and 2 Docket Nos. 50-275 and 50-323 Letter dated October 26, 2005 TAC Nos. MC6693 and MC6694