ML082380013
| ML082380013 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/05/2008 |
| From: | Wang A Plant Licensing Branch IV |
| To: | Entergy Operations |
| Wang, A B, NRR/DORL/LPLIV, 415-1445 | |
| References | |
| ANO1-ISI-009, TAC MD8016, TAC MD8018 | |
| Download: ML082380013 (9) | |
Text
September 5, 2008 Vice President, Operations Arkansas Nuclear One Entergy Operations, Inc.
1448 S.R. 333 Russellville, AR 72802
SUBJECT:
ARKANSAS NUCLEAR ONE, UNIT NO. 1 - APPROVAL OF REQUEST FOR RELIEF NO. ANO1-ISI-009 FOR THE THIRD 10-YEAR INSERVICE INSPECTION INTERVAL AND WITHDRAWAL OF REQUEST FOR RELIEF NO.
ANO1-ISI-011 (TAC NO. MD8016 AND MD8018)
Dear Sir or Madam:
By letter dated January 22, 2008, Entergy Operations, Inc. (Entergy, the licensee) submitted Request for Relief Nos. ANO1-ISI-009, ANO1-ISI-010, and ANO1-ISI-011 for the remainder of the Third 10-year Inservice Inspection Interval at Arkansas Nuclear One, Unit No. 1, to the U.S.
Nuclear Regulatory Commission (NRC).
By letter dated April 18, 2008, the licensee withdrew its Request for Relief No. ANO1-ISI-011.
The Request for Relief No. ANO1-ISI-010 was authorized by NRC it its letter dated July 23, 2008, which also acknowledged that Request for Relief No. ANO1-ISI-011 had been withdrawn.
For Request for Relief No. ANO1-ISI-009, in lieu of using the techniques of Article 4 of Section V of the American Society of Mechanical Engineers Code (ASME Code) when performing volumetric (ultrasonic) examination of the reactor pressure vessel (RPV) shell-to-flange weld, Request for Relief No. ANO1-ISI-009 proposes using qualified personnel and procedures for remote mechanized examination in accordance with the 1995 Edition with 1996 Addenda, for the RPV shell-to-flange weld. These examinations will be conducted with qualified vendor procedures for detection and length/depth sizing of ferritic material with a nominal thickness up to 12.3 inches for single or dual-sided applications.
The NRC staff completed its review of Request for Relief No. ANO1-ISI-009. Based on the enclosed safety evaluation (SE), the NRC staff determined that the proposed Request for Relief ANO1-ISI-009, will provide an acceptable level of quality and safety. Therefore, pursuant to paragraph 50.55a(a)(3)(i) of Title 10 of the Code of Federal Regulations, the NRC staff authorizes the use of Relief Request ANO1-ISI -009 at ANO-1.
If you have any questions regarding the SE, please contact Alan B. Wang at (301) 415-1445.
Sincerely,
/RA/
Michael T. Markley, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-313
Enclosure:
Safety Evaluation cc w/encl: See next page
- SE Input Memo, **NLO w/comments OFFICE NRR/LPL4/PM NRR/LPL4/LA DCI/CVIB/BC OGC(**)
NRR/LPL4/BC NRR/LPL4/PM NAME AWang GLappert MMitchell*
RVHolmes MMarkley AWang DATE 08/27/08 8/25/08 7/28/08 09/3/08 9/05/08 9/05/08
Arkansas Nuclear One (2/25/08) cc:
Senior Vice President Entergy Nuclear Operations P.O. Box 31995 Jackson, MS 39286-1995 Vice President, Oversight Entergy Nuclear Operations P.O. Box 31995 Jackson, MS 39286-1995 Senior Manager, Nuclear Safety
& Licensing Entergy Nuclear Operations P.O. Box 31995 Jackson, MS 39286-1995 Senior Vice President
& Chief Operating Officer Entergy Operations, Inc.
P.O. Box 31995 Jackson, MS 39286-1995 Associate General Counsel Entergy Nuclear Operations P.O. Box 31995 Jackson, MS 39286-1995 Manager, Licensing Entergy Operations, Inc.
Arkansas Nuclear One 1448 SR 333 Russellville, AR 72802 Section Chief, Division of Health Radiation Control Section Arkansas Department of Health and Human Services 4815 West Markham Street, Slot 30 Little Rock, AR 72205-3867 Section Chief, Division of Health Emergency Management Section Arkansas Department of Health and Human Services 4815 West Markham Street, Slot 30 Little Rock, AR 72205-3867 Pope County Judge Pope County Courthouse 100 W. Main Street Russellville, AR 72801 Senior Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 310 London, AR 72847 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 612 E. Lamar Blvd., Suite 400 Arlington, TX 76011-4125
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR RELIEF ANO1-ISI-009 FROM THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS BOILER AND PRESSURE VESSEL CODE, SECTION XI, THIRD 10-YEAR INSERVICE INSPECTION INTERVAL ENTERGY OPERATIONS, INC ARKANSAS NUCLEAR ONE UNIT 1 DOCKET NO. 50-313
1.0 INTRODUCTION
By a letter dated January 22, 2008 (Agencywide Document Access and Management System (ADAMS) Accession No. ML080250308), to the U.S. Nuclear Regulatory Commission (NRC), Entergy Operations, Inc (Entergy, the licensee) submitted Request for Relief No. ANO1-ISI-009, for the remainder of the Third 10-year Interval Inservice Inspection Program of Arkansas Nuclear One, Unit 1 (ANO-1). In lieu of using the techniques of Article 4 of Section V of the American Society of Mechanical Engineers (ASME) Code when performing volumetric (ultrasonic) examination of the reactor pressure vessel (RPV) shell-to-flange weld, Request for Relief No. ANO1-ISI-009 proposes using qualified personnel and procedures for remote mechanized examination in accordance with the 1995 Edition with 1996 Addenda, for the RPV shell-to-flange weld. These examinations will be conducted with qualified vendor procedures for detection and length/depth sizing of ferritic material with a nominal thickness up to 12.3 inches for single or dual-sided applications.
2.0 REGULATORY REQUIREMENTS Inservice inspection (ISI) of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) Class 1, 2, and 3 components is performed in accordance with Section XI of the ASME Code and applicable addenda as required by Title 10 Code of Federal Regulations (10 CFR) 50.55a(g), except where specific relief has been granted by the Nuclear Regulatory Commission (NRC) pursuant to 10 CFR 50.55a(g)(6)(i).
10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if: (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 Inservice Inspection 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 ten-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 ASME Code of record for the ANO-1 third 10-year ISI interval program is the 1992 Edition with no Addenda of Section XI of the ASME Code.
3.0 EVALUATION RR No. ANO1-ISI-009 ASME Code Components Reactor Pressure Vessel (RPV) Shell-to-Flange Weld No.01-001 ASME Code Requirements The current ASME Code of record governing inservice inspection for ANO-1 is the 1992 Edition. ASME Code,Section XI, 1992 Edition, Table IWB-2500-1, Examination Category B-A, "Pressure Retaining Welds in Reactor Vessel," Item B1.30 requires a volumetric examinationof essentially 100 percent of the weld length of the required examination volume as identified in Figure IWB-2500-4. Appendix I of Section XI of the ASME Code describes the ultrasonic examination requirements for components.
Additionally, Regulatory Guide (RG) 1.150, Revision 1, "Ultrasonic Testing of Reactor Vessel Welds during Pre-service and In-service Examinations" augments the ASME Code,Section V and Section XI requirements.
Licensees Basis for Relief Request (As Stated)
The prescriptive, amplitude-based ultrasonic examination techniques of the 1992 Edition of ASME [Code,] 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 [ASME Code,] 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 (hereafter referred to as Appendix VIII).
The performance-based techniques of Appendix VIII are required for all other Reactor Vessel Shell Weld examinations, having replaced Article 4 techniques.
Radiation exposure will be reduced since the 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 enhancements over the prescriptive amplitude-based techniques as described below:
(a)
Increased Sensitivity to Flaws: The Appendix VIII procedure is more sensitive to flaws because the examination sensitivity level compares to that of an ASME distance amplitude correction (DAC) level of five to ten percent, which is the highest practical level for ultrasonic testing. Examinations in accordance with Article 4 are conducted at a 50 percent DAC for the outer 80 percent of the wall thickness and 20 percent for the inner 20 percent of the wall thickness. The Appendix VIII procedure requires all signals interpreted by the analyst as flaws to be measured and assessed in accordance with the applicable acceptance criteria, regardless of amplitude. This recognizes that some flaws can exhibit a low amplitude response depending on orientation. The Article 4 techniques traditionally have a flaw recording 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 Appendix VIII. The proposed procedure complies with ASME 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 amplitude-based Article 4 techniques that have been proven inaccurate.
(c)
Compatibility of the Appendix VIII examination technique with ANO-1 RPV shell-to-flange geometry and previous ISI examinations for data comparison : The proposed Appendix VIII examination procedure will use the 45 degree beam angle in four orthogonal directions applied to the weld and examination volume by various transducer types, each covering a specified depth range.
The incremental scanlines will be 0.5 inches and examination will be conducted to the maximum extent practical.
The previous remote mechanized examination of the shell-to-flange weld was conducted at
[ANO-1] in 1995. At that time, 45, 60 and 70-degree examination angles were used. Results were acquired and analyzed using automated ultrasonic examination systems and subsequently evaluated to the applicable criteria in ASME Section XI. [Archival data] from the previous examination is available for comparison purposes to the proposed examination.
[Use of personnel and procedures qualified to the 1995 Edition with 1996 Addenda of Appendix VIII, for the reactor vessel shell-to-flange weld provides an equivalent or better level of quality and safety than the current Article 4 examination requirements.]
Licensees Proposed Alternative Examination (As Stated)
[In lieu of using the techniques of Article 4,] when performing volumetric (ultrasonic) examination of the [RPV] shell-to-flange weld, Entergy proposes using qualified personnel and procedures for remote mechanized examination in accordance with the 1995 Edition with 1996 Addenda, for the [RPV] shell-to-flange weld. These examinations will be conducted with qualified vendor procedures for detection and length/depth sizing of ferritic material with a nominal thickness up to 12.3 inches for single or dual-sided applications.
Staff Evaluation The 1992 Edition of ASME Code,Section XI, IWA-2232 states, "Ultrasonic examination shall be conducted in accordance with Appendix I." ASME Code,Section V, Article 4 provides a prescriptive process for qualifying UT of procedures and the scanning requirements for examinations. The UT performed to Article 4 uses detailed criteria for setting up and calibrating equipment, calculating coverage, and detecting indications. The capability of an Article 4 UT examination is demonstrated with calibration blocks made from representative material containing holes and notches.
The licensee proposes, in lieu of the Article 4 angle beam examination to use an examination that will be performed using examination procedures, personnel, and equipment qualified in accordance with ASME Code,Section XI, Appendix VIII, Supplements 4 and 6, as modified by 10 CFR 50.55a. 10 CFR 50.55a limits the use of with ASME Code,Section XI, Appendix VIII to the 2001 Edition of the ASME Code with no Addenda. ASME Code,Section XI, Appendix VIII is a performance-based UT method.
Performance-based UT requires that detailed criteria be used for performance demonstration tests. The results for the tests are compared against statistically developed screening criteria. The tests are performed on representative mockups containing flaws similar to those found in operating plants. The performance-based tests demonstrate the effectiveness of UT personnel and procedures. Examinations are performed with the scanning requirements for Supplements 4 and 6 that are provided in 10 CFR 50.55a(b)(2)(xv)(G), and the scanning volume identified in the ASME Code,Section XI, Figure IWB-2500-4 for the shell-to-flange weld. The scanning requirements are: (1) for the examination of the inner 15 percent through-wall volume, scanning will be performed in four orthogonal directions to the maximum extent possible with procedures and personnel qualified to with ASME Code,Section XI, Appendix VIII, Supplement 4 or; (2) if the inner 15 percent through-wall volume examination is not possible as required above, the inner 15 percent through-wall volume is considered fully examined if coverage is obtained in at least one parallel and one perpendicular direction using personnel and procedures qualified for single side examination in accordance with ASME Code,Section XI, Appendix VIII, Supplement 4 and Supplement 6; and (3) the remaining 85 percent through-wall volume is considered fully examined if coverage is obtained in one parallel and one perpendicular direction using procedures and personnel qualified for single side examination. Single side qualification criteria are provided in 10 CFR 50.55a(b)(2)(xv)(G)(2) and 10 CFR 50.55a(b)(2)(xvi).
The procedures, equipment, and personnel qualified to Appendix VIII have shown a high probability of flaw detection, and have increased the reliability of examinations of weld configurations within the scope of the PDI program. Therefore, the proposed alternative will provide an acceptable level of quality and safety.
4.0 CONCLUSION
The NRC staff reviewed the licensees proposed alternative to apply Appendix VIII examination requirements when volumetrically examining RPV Shell-to-Flange Weld No.01-001 by UT. Based on the above evaluation, the NRC staff concludes that the procedures, equipment, and personnel qualified to Appendix VIII have shown a high probability of flaw detection, and have increased the reliability of examinations of weld configurations within the scope of the PDI program and the proposed alternative will provide an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the licensees proposed alternative is authorized for ANO-1 for the remainder of the third 10-year ISI interval.
All other ASME Code,Section XI requirements for which relief was not specifically requested and approved in the subject requests for relief remain applicable, including third-party review by the authorized Nuclear Inservice Inspector.
Principal Contributor: T. McLellan Date: September 5, 2008