ML24362A130

Alloy 600 Management Program Plan

ML24362A130
Person / Time
Site:	Palo Verde
Issue date:	01/14/2025
From:	William Orders Plant Licensing Branch IV
To:	Heflin A Arizona Public Service Co
Orders, William
References
EPID L-2024-LLL-0003
Download: ML24362A130 (1)

Text

January 14, 2025 Adam C. Heflin Executive Vice President/

Chief Nuclear Officer Mail Station 7605 Arizona Public Service Company P.O. Box 52034 Phoenix, AZ 85072-2034

SUBJECT:

PALO VERDE NUCLEAR GENERATING STATION UNITS 1, 2, AND 3 -

LICENSE RENEWAL COMMITMENT 23 ALLOY 600 MANAGEMENT PROGRAM (EPID L-2024-LLL-0003)

Dear Adam Heflin:

By letter dated February 22, 2024, Arizona Public Service Company (the licensee) submitted the Palo Verde Nuclear Generating Station (PVNGS) Units 1, 2, and 3 Alloy 600 Management Program Plan to the U.S. Nuclear Regulatory Commission (NRC) for review in compliance with license renewal Commitment 23 of Table 19.5-1 of the PVNGS Updated Final Safety Analysis Report (UFSAR).

The NRC staff has reviewed the PVNGS Units 1, 2, and 3 Alloy 600 Management Program Plan in accordance with the requirements for a license renewal activity, as it was a license renewal commitment, to determine if the program demonstrates the ability to manage the effects of aging in nickel-based components per Title 10 of the Code of Federal Regulations (10 CFR) 54.21(a)(3).

The NRC staff has found in the review of licensees Alloy 600 Management Program Plan as a plant-specific program, that it meets the commitments made by the applicant and the requirements established in the Standard Review Plan License Renewal for structures and/or components made of nickel alloy material.

On the basis of its technical review of the licensees Alloy 600 Management Program Plan, the NRC staff concludes that the licensee has demonstrated that effects of aging will be adequately managed at PVNGS Units 1, 2, and 3 so that the intended functions will be maintained consistent with the current licensing basis for the period of extended operation, as required by 10 CFR 54.21(a)(3).

The staffs safety evaluation is documented in the enclosure to this letter.

If you have any questions, please contact me at (301) 415-3329 or via email at William.Orders@nrc.gov.

Sincerely,

/RA/

William Orders, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-528, 50-529, and 50-530 Renewed Operating License Nos. NPF-41, NPF-51, and NPF-74

Enclosure:

As stated cc: Listserv

Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RENEWED OPERATING LICENSE NUMBERS NPF-41, NPF-51, and NPF-74 LICENSE RENEWAL COMMITMENT 23 ALLOY 600 MANAGEMENT PROGRAM ARIZONA PUBLIC SERVICE COMPANY PALO VERDE NUCLEAR GENERATING STATION UNITS 1, 2, AND 3 DOCKET NOS. 50-528, 50-529, AND 50-530

1.0 INTRODUCTION

As required by license renewal Commitment 23 in Table 19.5-1 of the Palo Verde Nuclear Generating Station (PVNGS) Updated Final Safety Analysis Report (UFSAR), Arizona Public Service Company (APS) is providing the PVNGS Units 1, 2, and 3 Alloy 600 Management Program Plan for the Nuclear Regulatory Commission (NRC) staff review and approval.

(Agencywide Documents Access and Management System (ADAMS) Accession No. ML24053A397).

Specifically, Commitment 23, Item A, states:

Reactor Coolant System Nickel Alloy Pressure Boundary Components Implement applicable (1) NRC Orders, Bulletins and Generic Letters associated with nickel alloys and (2) staff-accepted industry guidelines, (3) participate in the industry initiatives, such as owners group programs and the EPRI Materials Reliability Program, for managing aging effects associated with nickel alloys, (4) upon completion of these programs, but not less than 24 months before entering the period of extended operation, APS will submit an inspection plan for reactor coolant system nickel alloy pressure boundary components to the NRC for review and approval The NRC staff has reviewed the PVNGS Units 1, 2, and 3 Alloy 600 Management Program Plan (Alloy 600 Management Program Plan) in accordance with the requirements for a license renewal activity, as it was a license renewal commitment, to determine if the program demonstrates the ability to manage the effects of aging in nickel-based components per Title 10 of the Code of Federal Regulations (10 CFR) 54.21(a)(3).

2.0 STAFF EVALUATION In accordance with 10 CFR 54.21(a)(3), the NRC staff reviewed the licensees Alloy 600 Management Program Plan to ensure that the effects of aging will be adequately managed for each component so that the intended function(s) will be maintained consistent with the current licensing basis for the period of extended operation.

The NRC staff focused its review on the licensees Alloy 600 Management Program Plan, which maintains plant safety, minimizes the impact of cracking due to primary water stress corrosion cracking (PWSCC) for nickel alloy component locations, and develops and executes short and long-term strategies for Alloy 600 management. The licensee noted that all aspects of this plan shall comply with industry and regulatory guidance for inspections and repairs and that it addresses the following Regulatory Commitment Tracking System (RCTS) items.

1. RCTSAI 3246893 - Credited in the License Renewal Application (LRA) Boric Acid Corrosion Program and associated with the Boric Acid Corrosion study.

2. RCTSAI 3246894 - Credited in the LRA Nickel Alloy Penetration Nozzles Welded to the Upper Reactor Closure Heads of Pressurized Water Reactors Program and associated with the Nickel Alloy Penetration Nozzles study 13-LS-A105.

3. RCTSAI 3260208 & 3246929 - Credited in the LRA Nickel Alloy Aging Management Program and associated with the Nickel Alloy Aging Management study 13-LS-A134.

As such, the licensee has ensured that any change to the Alloy 600 Management Program Plan will be reviewed by the License Renewal Group for any effect on the LRA. Further, the licensee has controls in effect that these commitments shall not be removed or changed without prior review by the licensees Regulatory Affairs group.

The Standard Review Plan for License Renewal (SRP LR), NUREG-1800, Rev. 2, contains the NRC staff's generic evaluation of existing plant programs and documents the technical basis for determining where existing programs are adequate without modification for the extended period of operation. Guidance for a generic review of an aging management program of which the licensees Alloy 600 Management Program Plan is a part is provided in Section A.1 Aging Management Review, of the SRP LR. The NRC staff reviewed the licensees Alloy 600 Management Program Plan against the aging management plan (AMP) elements found in Section A.1.2.3 based on the licensees submittal.

(1) Scope of the Program -the licensees Alloy 600 Management Program Plan will manage cracking due to PWSCC for the nickel alloy component locations identified in Section 5.0, Alloy 600 Locations. These locations include the bottom mounted instrumentation nozzles, pressurizer instrumentation nozzle welds and weld pads, reactor coolant system dissimilar metal butt welds both mitigated by full structural weld overlays or unmitigated at cold leg operating temperatures, reactor coolant system piping instrument nozzles, steam generator instrumentation line welds on Units 1 and 3, and the reactor vessel o-ring flange leak-off line.

The NRC staff notes that these nickel alloy components are managed under several programs such as 10 CFR 50.55a which specifiesSection XI requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, license renewal programs, Boric Acid Corrosion Prevention Program, Steam Generator Management Program, and several Code Cases, such as N-722-1, N-729-6 and N-770-5 which are mandated augmented inservice inspection (ISI) programs under 10 CFR 50.55a(g)(6)(ii).

The NRC staff confirms that the scope of the program program element satisfies the criterion defined in SRP LR Section A.1.2.3.1. The NRC staff finds this program element acceptable.

(2) Preventive Actions - The Alloy 600 Management Program Plan is the basis for an inspection program and designates condition monitoring. In Table 1 of Attachment 1 of the licensees submittal, the licensee identifies mitigation strategies and planned replacements or mitigations. The licensee also notes the interactions between the Alloy 600 Management Program Plan and the Boric Acid Corrosion Prevention Program to meet the plan objectives of maintaining plant safety and minimizing the impact of PWSCC on plant availability.

Based on this review, the NRC staff confirms that the preventive actions program element satisfies the guidance in SRP LR Section A.1.2.3.2. The NRC staff finds this program element acceptable.

(3) Parameters Monitored or Inspected - The licensees Alloy 600 Management Program Plan monitors for indications of cracking due to PWSCC in Alloy 600 components in the PVNGS Units 1, 2, and 3 primary systems. The licensees Alloy 600 Management Program Plan notes the use of the ASME Code Section XI inspection regulatory requirements for augmented ISI and various industry guidance programs. The NRC has approved, in accordance with 10 CFR 50.55a, the specific techniques and frequencies for monitoring nickel alloy components, which are prescribed by ASME Code Section XI for those components examined in accordance with the ISI and augmented ISI programs.

The NRC staff notes that the licensees Alloy 600 Management Program Plan uses the appropriate volumetric, surface and visual non-destructive examination (NDE) techniques for detection of degradation of the components identified in the scope of the program as required by NRC regulations, ASME Code and industry guidance.

Based on this review, the NRC staff confirms that the parameters monitored or inspected program element satisfies the guidance in SRP LR Section A.1.2.3.3. The NRC staff finds this program element acceptable.

(4) Detection of Aging Effects - The licensees Alloy 600 Management Program Plan uses the ASME Code Section XI inspection regulatory requirements for augmented ISI and various industry guidance programs. The NRC has approved, in accordance with 10 CFR 50.55a, the specific techniques and frequencies for monitoring nickel alloy components, which are prescribed by ASME Code Section XI for those components examined in accordance with the ISI program. These inspections are performed as directed by the augmented ISI program, the Steam Generator Management Program, or the Boric Acid Corrosion Prevention Program. Each of these programs for the detection of aging effects has been analyzed by the NRC to provide adequate detection capability.

Based on this review, the NRC staff confirms that the licensees commitment in the detection of aging effects program element satisfies the guidance in SRP LR Section A.1.2.3.4. The NRC staff finds this program element acceptable.

(5) Monitoring and Trending - The licensees Alloy 600 Management Program Plan relies on periodic inspections performed by the ISI program, the Steam Generator Management Program, and the Boric Acid Corrosion Prevention Program to detect and address degradation. The augmented ISI program directs Alloy 600 inspections according to the regulatory requirements of 10 CFR 50.55a and industry guidance including Code Cases N-722-1, N-729-6, and N-770-5. These augmented inspection programs and industry programs not only establish inspection programs for monitoring Alloy 600 components and welds, but they also adapt those inspection plans to trend indications of cracking in those components as well as scope expansion criteria to provide reasonable assurance that structural integrity will be maintained for the subject Alloy 600 components and weld.

Based on this review, the NRC staff confirms that the monitoring and trending program element satisfies the guidance in SRP LR Section A.1.2.3.5. The NRC staff finds this program element acceptable.

(6) Acceptance Criteria - The licensees Alloy 600 Management Program Plan uses the ASME Code Section XI inspection requirements ISI and staff accepted industry guidance. In general, the acceptance criteria of Alloy 600 component inspection programs are based on the scope and reporting requirements established by the ASME Code as required by 10 CFR 50.55a. Each of the required augmented ISI ASME Code Cases have specific acceptance criteria.

Based on this review, the NRC staff confirms that the acceptance criteria program element satisfies the guidance in SRP LR Section A.1.2.3.6. The NRC staff finds this program element acceptable.

(7) Corrective Actions - The licensee notes in the Alloy 600 Management Program Plan several repair alternatives that address corrective actions to address PWSCC aging effects of Ni-based alloys. Specifically, Table 1 of Attachment 1 of the licensees Alloy 600 Management Program Plan uses the repair and replacement requirements of ASME Code Section XI for ISI and staff accepted industry guidance. The NRC endorses the use of these repair and replacement activities through incorporation into the requirements of 10 CFR 50.55a, NRC approved ASME Code Cases or specific NRC authorized proposed alternatives. These are contained in the Repair or Replacements, Mitigation Strategy, and Planned Replacement/ Mitigation columns of Table 1.

Based on this review, the NRC staff confirms that the corrective actions program element satisfies the guidance in SRP LR Section A.1.2.3.7. The NRC staff finds this program element acceptable.

(8) Confirmation Process - The confirmation process for the licensees Alloy 600 Management Program Plan uses Site quality assurance procedures, review and approval processes, and administrative controls. These are implemented in accordance with the requirements of 10 CFR Part 50, Appendix B.

Based on this review, the NRC staff confirms that the confirmation process program element satisfies the guidance in SRP LR Section A.1.2.3.8. The NRC staff finds this program element acceptable.

(9) Administrative Controls - The administrative controls for the licensees Alloy 600 Management Program Plan are reviewed, approved, and maintained as controlled documents in accordance with the procedure control process and the quality assurance program.

Based on this review, the NRC staff confirms that the administrative controls program element satisfies the guidance in SRP LR Section A.1.2.3.9. The NRC staff finds this program element acceptable.

(10) Operating Experience - The licensees Alloy 600 Management Program Plan provides industry experience regarding PWSCC and associated reactor coolant leakage incidents.

Specifically, the licensee notes several components that have been replaced or mitigated at PVNGS Units 1, 2, and 3 including the reactor pressure vessel upper heads, steam generators with Alloy 690 tubing, pressurizer heater sleeves, higher operating temperature instrumentation nozzles, and the higher operating temperature dissimilar metal butt welds in the primary system.

The licensees Alloy 600 Management Program Plan is part of the licensees license renewal commitment for reactor coolant system nickel alloy pressure boundary components to implement NRC generic correspondence, the NRC staff accepted industry guidelines and participate in industry initiatives, such as the owners group programs and the Electric Power Research Institute (EPRI) Materials Reliability Program. The NRC staff believes these commitments will allow the licensee to follow industry efforts investigating the aging effects applicable to nickel-based alloys, continue to identify the appropriate aging management activities, and implement the appropriate recommendations resulting from this guidance. The licensee provided examples of operating experience to support that the licensees activities to address PWSCC in nickel alloy components has been, and will continue to be, effective in managing the aging effects of components within the scope of the program.

The NRC staff specifically reviewed the licensees actions regarding the implementation of Note 10 of Table 1 of ASME Code Case N-770-5 in regard to the examination of full structural weld overlays during the period of extended operation. The NRC staff found the licensees actions were in line with regulatory requirements for future planned examinations. The NRC staff also verified the licensees implementation of EPRI Technical Report 3002012244, Revision 3, Nondestructive Evaluation: Guideline for Conducting Ultrasonic Examinations of Dissimilar Metal Welds, dated February 2018. Verification of both of these items provides reasonable assurance that the licensees Alloy 600 Management Program Plan is a well-maintained tool of an effective aging management program that will continue to be updated as additional operating experience is identified.

Based on this review, the NRC staff confirms that the operating experience program element satisfies the guidance in SRP LR Section A.1.2.3.10. The NRC staff finds this program element acceptable.

In addition to the above, the NRC staff finds that the requirements of 10 CFR 50.55a (including required Code Cases) are bounding with respect to the recommendations contained in the SRP LR. Therefore, the NRC staff finds that continued adherence by the licensee to current regulatory requirements is sufficient to adequately manage the aging of the subject components in the licensees Alloy 600 Management Program Plan.

3.0 CONCLUSION

The NRC staff has reviewed the licensees Alloy 600 Management Program Plan as a plant-specific program and finds that it meets the commitments made by the applicant and the requirements established in the SRP LR for structures and/or components made of nickel alloy material.

On the basis of its technical review of the licensees Alloy 600 Management Program Plan, the NRC staff concludes that the licensee has demonstrated that effects of aging will be adequately managed at PVNGS Units 1, 2, and 3 so that the intended functions will be maintained consistent with the current licensing basis for the period of extended operation, as required by 10 CFR 54.21(a)(3).

Principal Contributor: J. Collins, NRR Date: January 14, 2025

ML24362A130 OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DNRL/NPHP/BC NAME WOrders PBlechman MMitchell DATE 12/27/2024 1 /13/2025 1/14/2025 OFFICE NRR/DORL/LPL/BC NRR/DORL/LPL4/PM NAME TNakanishi WOrders DATE 1/ 14 /2025 1 /14/2025