ML083570013
| ML083570013 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 05/22/2009 |
| From: | Lois James Plant Licensing Branch III |
| To: | Jensen J Indiana & Michigan Electric Co |
| beltz T, NRR/DORL/LPL3-1, 301-415-3049 | |
| References | |
| TAC MD9998 | |
| Download: ML083570013 (6) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 22, 2009 Mr. Joseph N. Jensen Senior Vice President and Chief Nuclear Officer Indiana Michigan Power Company Nuclear Generation Group One Cook Place Bridgman, MI 49106
SUBJECT:
DONALD C. COOK NUCLEAR PLANT, UNIT 1 (CNP-1) - RELIEF REQUEST (ISIR-26) RELATED TO REACTOR PRESSURE VESSEL SHELL-TO-FLANGE WELD EXAMINATION (TAC NO. MD9998)
Dear Mr. Jensen:
By letter to the U.S. Nuclear Regulatory Commission (NRC) dated October 7, 2008, Indiana Michigan Power Company (the licensee) submitted a request for relief from certain examination requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) for CNP-1. The licensee proposed examining the reactor pressure vessel shelf-to-flange weld with procedures, equipment, and personnel qualified to the 1995 Edition through 1996 Addenda of the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6, as modified by Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a.
As documented in the enclosed Safety Evaluation, the NRC staff concludes that the proposed alternative provides an acceptable level of quality and safety. Pursuant to 10 CFR 50.55a(a)(3)(i),
the proposed alternative is authorized for the subject weld at CNP-1 for the third 10-year inservice inspection interval which began on July 1, 1996, and is scheduled to end on February 28, 2010.
If you have any questions, please contact Terry Beltz of my staff at (301) 415-3049.
Sincerely,
'c4-VJ~~
Lois M. JameSS6hief Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-315
Enclosure:
Safety Evaluation cc w/encl: Distribution via ListServ
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BYTHE OFFICE OF NUCLEAR REACTOR REGULATION INSERVICE INSPECTION PROGRAM INDIANA MICHIGAN POWER COMPANY DONALD C. COOK NUCLEAR PLANT, UNIT 1 DOCKET NO. 50-315
1.0 INTRODUCTION
By letter dated October 7, 2008 (Agencywide Documents Access and Management System Accession No. ML083010237), Indiana Michigan Power Company (the licensee) requested relief from certain examination requirements of the American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code (Code) at the Donald C. Cook Nuclear Plant, Unit 1 (CNP-1) through two relief requests (ISIR-26 and ISIR-27). This safety evaluation pertains only to ISIR-26, and a separate safety evaluation will be issued for ISIR-27.
The licensee proposed in ISIR-26 to examine the reactor pressure vessel (RPV) upper shell-to-f1ange weld with procedures and personnel qualified to ASME Code,Section XI, Appendix VIII, Supplements 4 and 6 requirements.
The request is for the remainder of the third 1O-yearinservice inspection (lSI) interval which began on July 1, 1996, and is scheduled to end on February 28, 2010.
2.0 REGULATORY REQUIREMENTS The lSI of ASME Code Class 1, 2, and 3 components is to be performed in accordance with Section XI of the ASME Code and applicable edition and addenda as required by Title 10 of the Code of Federal RegUlations (10 CFR) Section 50.55a(g), except where specific relief has been granted by the Commission pursuant to 10 CFR 50.55a(gX6)(i). The regulation at 10 CFR 50.55a(a)(3) states in part that alternatives to the requirements of paragraph (g) may be used when authorized by the Nuclear Regulatory Commission (NRC), if the applicant 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) will meet the requirements, except the design and access provisions and the preservice 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 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) 12 months prior to Enclosure
- 2 the start of the 120-month interval, subject to the limitations and modifications listed therein. The regulation at 10 CFR 50.55a(g)( 4)(iv) states that inservice examination of components and system pressure tests may meet the requirements set forth in subsequent editions and addenda that are incorporated by reference in paragraph 10 CFR 50.55a(b), subject to the limitations and modification listed in 10 CFR 50.55a(b) and subject to Commission approval. Portions of editions or addenda may be used provided that all related requirements of the respective editions or addenda are met.
The code of record for the third 1O-year lSI interval at CNP-1 is the 1989 Edition of the ASME Code.
3.0 TECHNICAL EVALUATION
FOR RELIEF REQUEST (ISIR-26) 3.1 Component Function/Description This relief request supports examination of ASME Code Class 1, RPV shell-to-flange weld, Table IWB-2500-1, Category B-A, Item Number B1.30, CNP-1 component identification number 1-RPV-A.
3.2 Code Requirement for Which Relief is Requested ASIVIE Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components,"
1989 Edition, Paragraph IWA-2232, requires that ultrasonic examinations be conducted in accordance with Appendix I.
Appendix I, 1-2100 requires that ultrasonic examination of vessel welds greater than 2-inch thickness shall be conducted in accordance with Article 4 of Section V, as supplemented by this Appendix. Supplements identified in Table 1-2000-1 shall be applied.
ASME Code,Section XI, 1989 Edition, Subsection IWA-2630 states that "The requirements of Appendix A of Article 4 are acceptable for vessels examined in accordance with Article 4 of Section V."
3.3 Licensee-Proposed Alternative The licensee proposed to perform an automated ultrasonic examination of the RPV shell-to-flange weld using procedures, personnel, and equipment that have been demonstrated and qualified in accordance with ASME Section XI, 1995 Edition with 1996 Addenda, Appendix VIII, Supplements 4 and 6 as amended by 10 CFR 50.55a.
3.4 Licensee Basis for the Alternative The ASME Code,Section V, Article 4, prescriptive-based process for qualifying ultrasonic testing (UT) procedures and performing examinations is obsolete. The regulation at 10 CFR 50.55a requires performance-based methods for examination of RPV shell welds. Appendix VIII requirements were developed and adopted to ensure the effectiveness of ultrasonic examinations within the nuclear industry by means of a rigorous, item-specific performance demonstration containing flaws of various sizes, locations, and orientations. The performance demonstration
- 3 process has established a high degree of confidence in the capability of personnel, procedures, and equipment to detect and characterize flaws that could be detrimental to the structural integrity of the RPV. The Performance Demonstration Initiative (POI) approach has demonstrated that for detection and characterization of flaws in the RPV, the LIT examination techniques are equal to or surpass the requirements of the ASME Code,Section V, Article 4 LIT examination requirements.
Though Appendix VIII is not required for the RPV shell-to-flange weld examination, the use of Appendix VIII, Supplements 4 and 6 criteria for detecting and sizing of flaws in this weld are equal to or exceed the requirements of ASME Code,Section V, Article 4. Therefore, the use of the proposed alternative will continue to provide an acceptable level of quality and safety.
3.5
NRC Staff Evaluation
The 1989 Edition of the ASME Code,Section V, Article 4, as supplemented by Appendix I, provides a prescriptive process for qualifying LIT procedures. In lieu of 1-21 OO(b) requirements, the licensee proposed using procedures, equipment, and personnel qualified in accordance with performance-based criteria as administered by the POI program for the examination of RPV shell-to-flange weld. The POI program implements the requirements of ASME Code 1995 Edition through 1996 Addenda,Section XI, Appendix VIII, Supplements 4 and 6 as modified by 10 CFR 50.55a(b)(2)(xv).
When prescriptive Section V, Article 4, LIT procedures were applied in a controlled setting containing real flaws in mockups and the sizing results were statistically analyzed according to the performance-based screening criteria in Section XI, Appendix VIII, the prescriptive-based sizing results were determined to be equal to or less effective than the sizing results From performance-based,Section XI, Appendix VIII procedures 1. The better sizing resulting from the use of Section XI, Appendix VIII is attributed to the echo-dynamic motion and tip diffraction criteria used by performance-based LIT techniques as opposed to the less accurate amplitude drop criteria of prescriptive-based,Section V, Article 4 requirements.
Recently, the ASME Code approved a change that permitted licensees to use Appendix VIII qualified procedures, equipment, and personnel for examinations of a component which Appendix VIII was not applicable, provided the component's material, size, and shape were within the scope of the qualified examination procedure. The NRC staff participated in the ASME Code committee consensus process and supported this action. The basis for supporting this change in the ASME Code is that Appendix VIII LIT qualifications are more rigorous than Section V, Article 4 qualifications. Appendix VIII qualifications are based on passing a blind test performed on representative mockups containing representative flaws, while a Section V, Article 4 qualification process relies on non-blind detection of machined marks in a calibration block.
For flaw detection and evaluation,Section V, Article 4 requires that an indication display a 20 percent or greater Distance Amplitude Correction Curve (DAC) on a cathode ray tube (CRT) screen. For performance-based LIT, the essential variable settings used during the performance demonstration are required for the examination which usually relies on a CRT image display of twice the background noise. The performance-based LIT is performed with higher sensitivity 1EPRI Report NP-6273, "Accuracy of Ultrasonic Flaw Sizinq Techniques for Reactor Pressure Vessels," dated March 1989.
- 4 which increases the chances of detecting a flaw when compared to prescriptive-based,Section V, Article 4 DAC requirements. Procedures, equipment, and personnel qualified through the Appendix VIII POI program have a high probability of flaw detection. Based on this, the staff concludes that the Appendix VII' POI program results and translates in an increased reliability for inspection of weld configurations within the scope of the POI qualified procedures, equipment and personnel.
4.0 CONCLUSION
Based on the increased reliability of inspections within the scope of the Appendix VIII POI program, as discussed above, the NRC staff concludes that the licensee's proposed alternative to use UT procedures, equipment, and personnel qualified to the 1995 Edition through 1996 Addenda of the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6 as modified by 10 CFR 50.55a for the RPV shell-to-flange weld (Relief Request ISIR-26) provides an acceptable level of quality and safety. Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the proposed alternative is authorized for the subject weld at CNP-1 for the remainder of the third 10-year lSI interval which is scheduled to end on February 28,2010.
All other ASME Code,Section XI requirements for which relief has not been specifically requested and approved in this relief request remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
Principal Contributor: Donald Naujock, NRR Date:
May 22, 2009
May 22, 2009 Mr. Joseph N. Jensen Senior Vice President and Chief Nuclear Officer Indiana Michigan Power Company Nuclear Generation Group One Cook Place Bridgman, MI 49106 SUB~IECT:
DONALD C. COOK NUCLEAR PLANT, UNIT 1 (CNP-1) - RELIEF REQUEST (ISIR-26) RELATED TO REACTOR PRESSURE VESSEL SHELL-TO-FLANGE WELD EXAMINATION (TAC NO. MD9998)
Dear Mr. Jensen:
By letter to the U.S. Nuclear Regulatory Commission (NRC) dated October 7,2008, Indiana Michigan Power Company (the licensee) submitted a request for relief from certain examination requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) for CNP-1. The licensee proposed examining the reactor pressure vessel shell-to-flange weld with procedures, equipment, and personnel qualified to the 1995 Edition through 1996 Addenda of the ASME Code,Section XI, Appendix VIII, Supplements 4 and 6, as modified by Title 10 of the Code of Federal Regulations (10 CFR) Section 50.55a.
As documented in the enclosed Safety Evaluation, the NRC staff concludes that the proposed alternative provides an acceptable level of quality and safety. Pursuant to 10 CFR 50.55a(a)(3)(i),
the proposed alternative is authorized for the subject weld at CNP-1 for the third 1O-yearinservice inspection interval which began on July 1, 1996, and is scheduled to end on February 28,2010.
If you have any questions, please contact Terry Beltz of my staff at (301) 415-3049, Sincerely, IRAJ Lois M. James, Chief Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-315
Enclosure:
Safety Evaluation cc w/encl: Distribution via ListServ Distribution:
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