ML25254A014
| ML25254A014 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 09/26/2025 |
| From: | Tony Nakanishi Plant Licensing Branch IV |
| To: | Entergy Operations |
| References | |
| EPID L-2025-LLR-0002 | |
| Download: ML25254A014 (1) | |
Text
September 26, 2025 ANO Site Vice President Arkansas Nuclear One Entergy Operations, Inc.
N-ADM-8 1448 S.R. 333 Russellville, AR 72802
SUBJECT:
ARKANSAS NUCLEAR ONE, UNITS 1 AND 2 - AUTHORIZATION OF ALTERNATIVE REQUESTS ANO1-ISI-24-02 AND ANO2-ISI-24-02 RELATED TO PRESSURIZER WELD EXAMINATION (EPID L-2025-LLR-0002)
Dear Sir or Madam:
By letter dated January 13, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25013A293), as supplemented by letter dated June 24, 2025 (ML25175A337), Entergy Operations, Inc. (Entergy, the licensee) requested approval of proposed alternatives for Arkansas Nuclear One, Units 1 and 2 (ANO-1 and ANO-2, respectively). The proposed Alternative Requests ANO1-ISI-24-02 and ANO2-ISI-24-02 are related to the alternative examination of pressurizer welds under Examination Category B-B, Item Nos. B2.11 and B2.12, and Examination Category B-D, Item No. B3.110, of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, table IWB-2500-1.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1), the licensee requested to use the proposed alternatives on the basis that the alternatives provide an acceptable level of quality and safety.
Based on the enclosed safety evaluation, the NRC staff has concluded that the licensees Alternative Requests ANO1-ISI-24-01 and ANO2-ISI-24-01, as supplemented by letter dated June 24, 2025, provide an acceptable level of quality and safety. Accordingly, the staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1). Therefore, the NRC staff authorizes the use of Alternative Request ANO1-ISI-24-01 at ANO-1 up to May 20, 2034, and Alternative Request ANO2-ISI-24-01 at ANO-2 up to July 17, 2038.
All other ASME Code,Section XI, requirements for which relief was not specifically requested and approved in the proposed alternative requests remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
If you have any questions, please contact the ANO Project Manager, Mahesh Chawla at 301-415-8371 or via email at Mahesh.Chawla@nrc.gov.
Sincerely, Tony Nakanishi, Chief Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-313 and 50-368
Enclosure:
Safety Evaluation cc: Listserv TONY NAKANISHI Digitally signed by TONY NAKANISHI Date: 2025.09.26 11:19:43 -04'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE REQUESTS ANO1-ISI-24-02 AND ANO2-ISI-24-02 RELATED TO PRESSURIZER WELD EXAMINATION ENTERGY OPERATIONS, INC.
ARKANSAS NUCLEAR ONE, UNITS 1 AND 2 DOCKET NOS. 50-313 AND 50-368
1.0 INTRODUCTION
By letter dated January 13, 2025 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML25013A293), as supplemented by letter dated June 24, 2025 (ML25175A337), Entergy Operations, Inc. (Entergy, the licensee) requested approval of proposed alternatives for Arkansas Nuclear One, Units 1 and 2 (ANO-1 and ANO-2, respectively). The proposed Alternative Requests ANO1-ISI-24-02 and ANO2-ISI-24-02 are related to the alternative examination of pressurizer welds under Examination Category B-B, Item Nos. B2.11 and B2.12, and Examination Category B-D, Item No. B3.110 of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, table IWB-2500-1.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(1),
Acceptable level of quality and safety, the licensee requested to use the proposed alternatives on the basis that the alternatives provide an acceptable level of quality and safety.
2.0 REGULATORY EVALUATION
The regulations in 10 CFR 50.55a(g), Preservice and inservice inspection requirements, require that ASME Code Class 1 pressure-retaining welds and nozzles be inspected during each inservice inspection (ISI) interval in accordance with the applicable edition of ASME Code,Section XI. The regulations in 10 CFR 50.55a(g)(4), Inservice inspection standards requirement for operating plants, state, in part, that ASME Code Class 1 components must meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, to the extent practical within the limitations of design, geometry, and materials of construction of the components.
The regulations in 10 CFR 50.55a(z), Alternatives to codes and standards requirements, states, in part, that alternatives to the requirements in paragraphs (b) through (h) of 10 CFR 50.55a may be used when authorized by the U.S. Nuclear Regulatory Commission (NRC) if the licensee demonstrates that: (1) the proposed alternative would provide an acceptable level of quality and safety, or (2) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
3.0 TECHNICAL EVALUATION
3.1 Licensees Proposed Alternative 3.1.1 ASME Code Component(s) Affected The affected components are ASME Code Class 1 pressurizer vessel head welds, shell-to-head welds, and nozzle-to-vessel welds. The affected welds are classified in accordance with ASME Code,Section XI, table IWB-2500-1. as Examination Categories.
B-B, Pressure Retaining Welds in Vessels Other Than Reactor Vessels B-D, Full Penetration Welded Nozzles in Vessels Associated with the above examination categories, item numbers are:
B2.11, pressurizer, shell-to-head welds, circumferential weld, B2.12, pressurizer, shell-to-head welds, longitudinal weld, and B3.110, pressurizer, nozzle-to-vessel welds.
Section 1.0 of the licensees submittal dated January 13, 2025, for Alternative Requests ANO1-ISI-24-02 and ANO2-ISI-24-02 presents the weld identification and description.
The NRC staff notes that the nuclear steam supply system of ANO-1 is a Babcock and Wilcox (B&W) design, whereas the ANO-2 has a Combustion Engineering (CE) design. As such, ANO-1 uses a B&W pressurizer and ANO-2 uses a CE pressurizer. The pressurizers in both units are similar in terms of functionality and operation. However, the number of welds and configuration of the pressurizers are slightly different between the two units. Therefore, analyses for the ANO-1 B&W pressurizer and ANO-2 CE pressurizer are slightly different, as discussed further in this safety evaluation.
3.1.2 Applicable Code Edition And Addenda The Code of Record for the current fifth 10-year ISI interval is the 2007 Edition through the 2008 Addenda of the ASME Code,Section XI for ANO-1 and ANO-2.
3.1.3 Applicable Code Requirement ASME Code,Section XI, IWB-2500(a), table IWB-2500-1, Examination Categories B-B and B-D require examination of the following item numbers:
B2.11 - Volumetric examination of both circumferential shell-to-head welds during each inspection interval.
B2.12 - Volumetric examination of one foot of all longitudinal shell-to-head welds that intersect circumferential welds during the first interval and one foot of one longitudinal shell-to-head weld that intersects a circumferential weld during successive intervals.
B3.110 - Volumetric examination of all full penetration nozzle-to-vessel welds during each inspection interval.
3.1.4 Reason For Request The licensee stated that Electric Power Research Institute (EPRI) report, Technical Bases for Inspection Requirements for PWR [Pressurized Water Reactor] Pressurizer Head, Shell-to-Head, Nozzle-to-Head Welds, 3002015905 (hereafter referred to as the EPRI report),
assesses the basis for the ASME Code,Section XI examination requirements for the subject pressurizer welds. The assessments included a survey of inspection results from 74 domestic and international nuclear units and flaw tolerance evaluations using probabilistic fracture mechanics (PFM) and deterministic fracture mechanics (DFM).
Based on the conclusions of the EPRI report, supplemented by plant-specific evaluations contained in its submittal dated January 13, 2025, the licensee requested an ISI examination deferral for the subject ANO-1 and ANO-2 pressurizer welds. The licensee stated that the EPRI report was developed consistent with the recommendations provided in the following three documents.
BWR [Boiling Water Reactor] Vessel & Internals Project (BWRVIP) Memo No. 2019-016, White Paper on Suggested Content for PFM Submittals to the NRC, dated February 27, 2019 (ML19241A545)
Regulatory Guide (RG) 1.245, Revision 0, Preparing Probabilistic Fracture Mechanics Submittals, January 2022 (ML21334A158)
NUREG/CR-7278, Technical Basis for the use of Probabilistic Fracture Mechanics in Regulatory Applications-Final, January 2022 (ML22014A406)
The NRC staff noted that the EPRI report was not submitted or reviewed as a topical report. The staff reviewed the proposed ANO alternative requests on a plant-specific basis. The NRC did not review the EPRI report for generic use, and the ANO review does not extend beyond the ANO-1 and ANO-2 plant-specific authorization.
3.1.5 Proposed Alternative ANO1-ISI-24-02 For ANO-1, the licensee requested an inspection alternative to the examination requirements of the ASME Code,Section XI, table IWB-2500-1 for the following examination categories and item numbers:
ASME Category Item No.
Description B-B B2.11 Pressurizer, Shell-to-Head Welds, Circumferential B-B B2.12 Pressurizer, Shell-to-Head Welds, Longitudinal B-D B3.110 Pressurizer, Nozzle-to-Vessel Welds The licensee stated that ANO-1 still has its original pressurizer. The pressurizer welds and components received the required preservice inspection (PSI) examinations followed by ISI examinations through the second period of the current fifth inspection interval.
The proposed alternative is to defer the ISI examinations for these item numbers from the current ASME Code,Section XI, 10-year requirement to the end of currently licensed operating life, which is scheduled to end on May 20, 2034. The licensee stated that this equates to an extension of 16 years, 11 months, 20 days from the end of the fourth ISI interval (May 30, 2017) at which time all ASME Code,Section XI, Division 1 requirements were satisfied.
ANO2-ISI-24-02 For ANO-2, the licensee requested an inspection alternative to the examination requirements of ASME Section XI, table IWB-2500-1 for the following examination categories and item numbers:
ASME Category Item No.
Description B-B B2.11 Pressurizer, shell-to-head welds, circumferential B-D B3.110 Pressurizer, nozzle-to-vessel welds The licensee stated that it replaced the ANO-2 pressurizer in the second period of the third ISI interval in 2006. The new pressurizer welds and components received the required PSI examinations followed by ISI examinations through the first period of the current fifth inspection interval.
The proposed alternative is to defer the ISI examinations for these item numbers from the current ASME Code,Section XI, 10-year requirement to the end of currently licensed operating life, which is scheduled to end on July 17, 2038. The licensee stated that this equates to an extension of 17 years, 3 months, 22 days from the end of the fourth ISI interval (March 25, 2021) at which time all ASME Code,Section XI, Division 1 requirements were satisfied.
3.1.6 Duration of Proposed Alternative For ANO1-ISI-24-02, the proposed alternative is requested for the remainder of the current fifth inspection interval and through the end of currently licensed operating life at ANO-1, which is currently scheduled to end on May 20, 2034.
For ANO2-ISI-24-02, the proposed alternative is requested for the remainder of the current fifth inspection interval and through the end of currently licensed operating life at ANO-2, which is currently scheduled to end on July 17, 2038.
3.2
NRC Staff Evaluation
3.2.1 Background and Evaluation Approach Alternative Requests ANO1-ISI-24-02 and ANO2-ISI-24-02 are described in the enclosure to the January 13, 2025, letter (hereafter referred to as the Enclosure). The Enclosure contains six attachments. Attachments 1 and 2 discuss the applicability of the EPRI report to ANO-1 and ANO-2 pressurizers, respectively. Attachment 3 contains the results of an industry survey of pressurizer examination history. Attachment 4 presents the finite element model and stress analysis of the surge nozzle and bottom head of a B&W pressurizer (i.e., Oconee pressurizer). contains the DFM and PFM analyses of the B&W pressurizer (Oconee pressurizer), which were taken from the Duke Energy submittal dated February 17, 2023 (ML23048A148). Attachment 6 contains the licensees regulatory commitments. All the references regarding attachments in this safety evaluation are related to Attachments to the Enclosure.
The EPRI report analyzes the structural integrity of welds associated with the pressurizer head, shell-to-head and attached nozzles. The EPRI report presents the DFM and PFM analyses for pressurizers that are used in Westinghouse Electric Company LLC (Westinghouse), CE and B&W designed nuclear plants. The NRC staff has approved alternative requests from other licensees that use the EPRI report as technical basis, as documented in the NRCs safety evaluation dated October 19, 2023 (ML23264A853) for the Duke Energy submittal dated February 17, 2023 (ML23048A148), and the Salem Generating Station, Units 1 and 2 safety evaluation dated June 10, 2021 (ML21145A189) for the PSEG Nuclear LLC (PSEG) submittal dated August 5, 2020 (ML20218A587). The safety evaluations for Duke Energy and PSEG submittals concluded that the methodologies used in the EPRI report were technically sound and acceptable for demonstrating the structural integrity of plant-specific pressurizer welds.
As stated above, ANO-1 uses a B&W-designed pressurizer and ANO-2 uses a CE-designed pressurizer. Therefore, the NRC staff evaluated certain aspects of the ANO-1 and ANO-2 pressurizers together as well as separately as discussed below.
ANO-1 During its review of the Duke Energy submittal, the NRC staff reviewed the applicability of the DFM and PFM methodology of the EPRI report to the Oconee pressurizer and the acceptability of the Oconee pressurizer considering deferred weld examination. As shown in its safety evaluation, the NRC staff determined that the EPRI methodology is acceptable and applicable to the Oconee pressurizer and that the deferred examination of the Oconee pressurizer welds is acceptable. Entergy used Duke Energys analysis for the Oconee pressurizer to represent the analysis for the ANO-1 pressurizer as shown in Attachments 4 and 5. Entergy stated that the Oconee pressurizer and ANO-1 pressurizer are of the same B&W design. In Attachment 1, Entergy compared the transients and loading between the Oconee pressurizer and ANO-1 pressurizer. In addition, the licensee performed a plant-specific PFM analysis for the ANO-1 pressurizer based on a plant-specific inspection scenario.
The focus of the NRC staffs review of the ANO-1 pressurizer is to assess the applicability of the Oconee pressurizer analysis to the ANO-1 pressurizer with respect to configuration, material selection, operating conditions, and applied loadings.
ANO-2 The licensee stated that the DFM and PFM analyses for the Westinghouse pressurizer configuration in the EPRI report are bounding relative to the CE pressurizer design at ANO-2.
The licensee applied the methodology and results of the DFM and PFM analyses in the EPRI report to the ANO-2 pressurizer. The licensee also performed a plant-specific analysis for the ANO-2 pressurizer welds. The NRC staff previously reviewed the applicability of the EPRI report to the Westinghouse pressurizer as shown in the NRCs safety evaluation for the Westinghouse pressurizer at Salem dated June 10, 2021 (ML21145A189). As such, the staff evaluated the structural integrity of the ANO-2 pressurizer welds based on the review of the applicability of the EPRI report and the plant-specific analyses performed for the ANO-2 pressurizer.
The NRC staff evaluated five major topics: Degradation Mechanisms, PFM Analysis, DFM Analysis, Performance Monitoring, and Degradation Management as shown below.
3.2.2 Degradation Mechanisms The EPRI report evaluated degradation mechanisms that could potentially impact the reliability of the pressurizer welds. The degradation mechanisms include stress corrosion cracking, environmental assisted fatigue, microbiologically influenced corrosion, pitting, crevice corrosion, erosion-cavitation, erosion, flow accelerated corrosion, general corrosion, galvanic corrosion, and mechanical/thermal fatigue. The licensee stated that other than the potential for environmental assisted fatigue and mechanical/thermal fatigue, there were no active degradation mechanisms that significantly affect the long-term structural integrity of the pressurizer welds covered in this request.
The EPRI report conducted a survey of 74 PWR units to determine their degradation history.
Most of these plants have operated for over 30 years and in some cases over 40 years. The survey did not identify any unknown degradation mechanisms (i.e., mechanisms other than those listed above). Based on this exhaustive industry survey, the licensee concluded that although the emergence of an unknown degradation mechanism cannot be completely ruled out, the possibility of the occurrence of such an unknown degradation mechanism is highly unlikely.
The NRC staff reviewed the licensees submittal for plant-specific circumstances that may indicate presence of a degradation mechanism and activity sufficiently unique to ANO-1 and ANO-2 to merit additional consideration. Such circumstances pertain to materials of the subject components, stress states, and reactor coolant environments. The staff found that the degradation mechanisms described by the licensee for ANO-1 and ANO-2 are addressed in a manner sufficient for the applicability of EPRI report and that no unknown degradation mechanisms were identified. The staff confirmed that the materials, stress states, and chemical environment (i.e., reactor coolant) of the subject pressurizer welds are consistent with the assumptions and analysis made in the EPRI report and that consideration of additional degradation mechanisms is not necessary. The staff noted that the EPRI report considered the fatigue-related mechanisms in the PFM and DFM evaluations. The staff determined that the materials and operating conditions for ANO-1 and ANO-2 are similar to those in the EPRI report and the conclusions of the EPRI report apply to ANO-1 and ANO-2 pressurizers. Therefore, the staff determined that the licensee has adequately identified fatigue as the applicable degradation mechanism for the ANO pressurizers. The staff further determined that the licensee has appropriately analyzed fatigue as part of its DFM and PFM analyses for the ANO pressurizers as discussed further in this safety evaluation.
3.2.3 PFM Analysis The PFM analysis in the EPRI report uses the Probabilistic Optimization of Inspection (PROMISE) Version 2.0 software. The NRC staff audited the PROMISE Version 1.0 software as discussed in the staffs audit plan for Vogtle Electric Generating Plants, Units 1 and 2, dated May 14, 2020 (ML20128J311). The staff determined that PROMISE Version 1.0 is acceptable for use on a case-by-case and plant-specific basis. However, the staff has not reviewed the PROMISE Version 2.0 software. The key difference between the two versions is that in PROMISE Version 1.0, the user-specified examination coverage is applied to all inspections, whereas in PROMISE Version 2.0, the examination coverage can be specified by the user uniquely for each inspection. Versions 1.0 and 2.0 assume 100 percent coverage for the PSI examination. The staff determined that PROMISE Version 2.0 is acceptable for use on a case-by-case basis using plant-specific information because the difference between Version 1.0 and Version 2.0 is not significant with respect to the calculation results as discussed in the staffs safety evaluation dated October 19, 2023 (ML23264A853), for the Duke Energy submittal.
The PFM analysis demonstrates that the probability of failure (PoF) for a postulated flaw in a pressurizer weld, under applied loading, is low. The acceptance criterion for the PoF applicable to the subject pressurizer welds is 1.0x10-6 failures per year.
The NRC staff noted that the acceptance criterion of 1.0x10-6 failures per year is tied to that used by the staff in the development of 10 CFR 50.61a, Alternate fracture toughness requirements for protection against pressurized thermal shock events, and other similar licensing reviews. In that Rule, the reactor vessel through-wall crack frequency (TWCF) of 1.0x10-6 events per year for a pressurized thermal shock event is an acceptable criterion, because reactor vessel TWCF is conservatively assumed to be equivalent to an increase in core damage frequency, and as such meets the guidance in RG 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis (ML17317A256). This assumption (TWCF = core damage frequency) is conservative because a through-wall crack in the reactor vessel does not necessarily increase the likelihood of core damage. The discussion of TWCF is explained in detail in the technical basis document for 10 CFR 50.61a, NUREG-1806 Technical Basis for Revision of the Pressurized Thermal Shock (PTS) Screening Limit in the PTS Rule (10 CFR 50.61),
August 2007 (ML072830074).
The NRC staff also noted that the TWCF criterion of 1.0x10-6 per year was generated using a conservative model for reactor vessel cracking. In addition, this criterion exists within the context of reactor pressure vessel surveillance programs and inspection programs. The staff finds that the licensees use of 1.0x10-6 failures per year for the acceptable PoF for pressurizer welds is acceptable because (a) the impact of an pressurizer weld failure would be less than the impact of a reactor vessel failure on overall plant risk, (b) the subject pressurizer welds have substantive, relevant, and continuing inspection histories and programs, and (c) the estimated risks associated with the individual weld are much lower than the system risk criterion (i.e., the system risk is dominated by a small sub-population which can be considered the principal system risk for integrity).
The failure of an individual weld is likely to represent only a limited contribution to risk. The NRC staff further noted that comparing the probability of leakage to the same criterion of 1.0x10-6 failures per year is conservative because leakage is not failure. The use of PoF criteria such as 1.0x10-6 per year for individual welds may not be appropriate generically, but based on the discussion above, the staff finds that the application of this criterion is acceptable for the plant-specific review for the ANO-1 and ANO-2 pressurizer welds.
Based on the above, the NRC staffs objective is to determine whether ANO-1 and ANO-2 pressurizer welds will satisfy the acceptance criterion of 1.0x10-6 failures per year based on the PFM analysis.
The NRC staff reviewed the following parameters or aspects significant to the PFM analysis of the subject pressurizer welds: selection of components and materials, selection of transients, other operating loads, finite element analysis, fracture toughness, flaw density, flaw crack growth (FCG) rate coefficient (or simply FCG rate), and effect of ISI schedule and examination coverage.
3.2.3.1 Selection of Components and Materials The NRC staff evaluated the plant-specific applicability of the components and materials selected and analyzed in the EPRI report to the subject ANO-1 and ANO-2 pressurizer welds.
The EPRI report evaluated representative component geometries, materials, and loading conditions that were used in the PFM and DFM analyses. Section 9 of the EPRI report specifies plant-specific applicability criteria with regards to component geometries, materials, and loading conditions that must be evaluated and met by each plant to determine the applicability of the EPRI report to a plant-specific pressurizer. The licensee addressed these criteria in table 1-1 of and table 2-1 of Attachment 2 for the ANO-1 and ANO-2 pressurizer welds, respectively.
The material of the ANO-1 pressurizer shell is SA-212 Grade B, and the nozzle is A-508-64 Class 1. The material of the ANO-2 pressurizer shell and surge nozzle are fabricated from SA-508, Grade 3, Class 1. The NRC staff verified that these materials conform with ASME Code,Section XI, appendix G, paragraph G-2110 as specified in the EPRI report. The staff finds that the materials for ANO-1 and ANO-2 meet the material applicability criterion of the EPRI report. Based on the above, the staff determined that ANO-1 and ANO-2 pressurizer welds meet the component geometry and materials applicability criteria in the EPRI report. Therefore, the staff finds that the EPRI report is applicable to ANO-1 and ANO-2 pressurizers in terms of material selection and compatibility.
3.2.3.2 Selection of Transients Section 5.2 of the EPRI report discusses the thermal and pressure transients under normal and upset conditions that are considered relevant to pressurizer welds. The EPRI report develops a list of transients for analysis applicable to the pressurizer welds based on transients that have the largest temperature and pressure variations. Attachments 1 and 2 evaluate the plant-specific applicability of the transients selected and analyzed in the EPRI report to the ANO-1 and ANO-2 pressurizer welds.
The NRC staff determined that the transients defined in section 5.2 of the EPRI report are reasonable for the ANO-1 and ANO-2 pressurizers because the selection was based on large temperature and pressure variations that are conducive to FCG that are expected to occur in PWRs. The staff confirmed that the plant-specific transients in ANO-1 and ANO-2 are bound by the transients used in the EPRI report.
The EPRI report does not include separate test conditions as part of the transient selection.
Section 5.1.2 in the Enclosure states that pressure tests are performed at normal operating conditions and no hydrostatic testing has been performed since the plant began operation at ANO-1 and ANO-2. The NRC staff noted that because the pressure tests are performed at normal operating conditions, they are part of heatup/cooldown. Therefore, test conditions need not be analyzed as a separate transient for ANO-1 and ANO-2.
The NRC staff determined that ANO-1 and ANO-2 meet the transient applicability criteria in the EPRI report. As such, the staff finds that transient loads analyzed are acceptable for the subject ANO pressurizer welds.
3.2.3.3 Other Operating Loads Regarding other operating loads, the NRC staff reviewed the application of weld residual stress and clad residual stress in the PFM analysis of pressurizer welds. Weld residual stress and cladding stresses are addressed in the EPRI report. The staff determined that ANO-1 and ANO-2 plant-specific aspects of this submittal do not warrant further consideration because of (1) the relatively low sensitivity of residual stress on the PFM results as shown in table 8-14 of the EPRI report; and (2) the small impact of clad residual stress on the PFM results. The staff finds that other operating loads would have an insignificant effect on the probability of leakage or rupture beyond the sensitivity studies documented in the EPRI report. Based on the above, the staff finds that the treatment of other loads in the PFM analysis is acceptable for the subject ANO pressurizer welds. The NRC staff concludes that the PFM analysis adequately bound other operating loads in the ANO pressurizer welds.
3.2.3.4 Finite Element Analysis The finite element analysis (FEA) is performed to obtain stresses (i.e., stress analysis) in the subject pressurizer welds. The stresses are used to perform crack growth analyses in the PFM and DFM analyses. Section 4 of the EPRI report discusses the variation among pressurizer designs as part of its FEA. In selecting the welds, EPRI considered geometry, operating characteristics, materials, field experience with respect to service-induced cracking, and the availability and quality of component-specific information. The NRC staff noted that the key parameter in the stress analysis (as part of the PFM analysis) of a vessel shell is the R/t ratio (R and t are the inside radius and wall thickness of the vessel, respectively). To verify the dominance of the R/t ratio in the FEA, the staff reviewed the through-wall stress distributions in section 7 of the EPRI report to confirm that the pressure stress is dominant, which would confirm the dominance of the R/t ratio. Accordingly, the staff finds that EPRIs analysis demonstrates that the R/t ratio is the dominant parameter in evaluating the various pressurizer configurations to determine whether the EPRIs analysis is applicable to the plant-specific ANO pressurizer welds.
ANO-1 presents a 3-dimensional (3-D) finite element model of a B&W pressurizer (i.e.,
the Oconee pressurizer). The model includes a local portion of the pressurizer lower shell and cladding (which includes the shell thickness increase at the heater bundle region), the pressurizer bottom head and cladding, and the surge nozzle and cladding. The finite element model of the pressurizer includes thermal transients and a unit internal pressure. For thermal loads due to thermal transients, the licensee performed thermal analyses to determine the temperature distribution time-histories for each transient. The temperature distributions are then used as input to perform stress analyses for each transient. For internal pressure, the licensee applied an arbitrary unit internal pressure to the finite element model. Due to the linear elastic nature of finite element modeling, the stress results from the unit pressure can be scaled to correspond to actual pressure values. In its safety evaluation dated October 19, 2023 (ML23264A853), the NRC staff reviewed and found acceptable the FEA of the Oconee pressurize submitted by Duke Energy. The staff noted that the material and configuration (e.g.,
R/t ratio) of the ANO-1 pressurizer are the same, similar to, or within the bounds of those of the Oconee pressurizer as shown in table 1 of the Enclosure. Therefore, the FEA of the Oconee pressurizer welds in Attachment 4 is applicable to the ANO-1 pressurizer.
ANO-2 The licensee stated that the FEA in the EPRI report was performed using representative Westinghouse plant geometries (which bound CE plants/pressurizers), bounding transients, and typical material properties. As stated above, the NRC staff previously approved a similar request for the Salem pressurizer as documented in the NRCs safety evaluation dated June 10, 2021 (ML21145A189). The Salem pressurizer is a Westinghouse-design, and the FEA supporting that request was based on the EPRI report. The staff verified that the applicability of the FEA analysis of the EPRI report to the ANO-2 pressurizer welds is demonstrated in Attachment 2 and confirms that the ANO-2 pressurizer has satisfied all plant-specific requirements specified in the EPRI report. In particular, the key geometric parameters (e.g., R/t ratio) of the ANO-2 pressurizer are within the bounds of the parameters used in the EPRI report as shown in tables 2 and 3 of the Enclosure. Based on the above, the staff determined that the FEA in the EPRI report is applicable to and acceptable for the ANO-2 pressurizer.
3.2.3.5 Fracture Toughness ANO-1 Table 1 of the Enclosure shows that the ANO-1 pressurizer shell or head is made of SA-212, Grade B, and the attached nozzle is made of A-508-64, Class 1. Attachment 5 states that the Oconee pressurizer materials are SA-212, Grade B; SA-516; and SA-508 Grade 1, Class 1. The NRC staff noted that the ANO-1 pressurizer material is similar to the Oconee pressurizer material. The licensee stated that fracture toughness provided in the ASME Code,Section XI, appendix A, only applies to low alloy ferritic steels such as SA-533 Grade B Class 1, SA-508 Class 2, and SA-508 Class 3 (typically used in the fabrication of Westinghouse and CE pressurizers) and is therefore not applicable to the B&W pressurizers. Attachment 5 states that the fracture toughness values for low carbon ferritic steel (applicable to the B&W pressurizer material) are provided in the ASME Code,Section XI, appendix C, which is intended for flaw evaluations in piping components. The licensee acknowledged that appendix C is not specifically applicable to pressurizer components; however, it applied the lower bound fracture toughness value (106 ksiin) provided for ferritic piping in the ASME Code,Section XI, appendix C, to postulated circumferential and axial flaws in the Oconee pressurizer. The staff determined that use of 106 ksiin for fracture toughness to analyze the Oconee pressurizer welds is acceptable because it is lower than and thus conservative as compared to the use of the fracture toughness value of 200 ksiin. Therefore, the staff finds that use of 106 ksiin for fracture toughness is applicable to the ANO-1 pressurizer.
ANO-2 The ANO-2 pressurizer shell and surge nozzle are fabricated from SA-508, Grade 3, Class 1, which conform to the requirements of the ASME Code,Section XI, appendix G, paragraph G-2110. The EPRI report used an upper-shelf KIC (fracture toughness) value of 200 ksiin based on the upper-shelf fracture toughness value specified in ASME Code,Section XI, appendix A, A-4200. The A-4200 fracture toughness curve refers to the same fracture toughness curve in the ASME Code,Section XI, appendix G, paragraph G-2110. The NRC staff determined that the ANO-2 pressurizer welds use an acceptable fracture toughness value of 200 ksiin because the welds conform to the fracture toughness requirements of the ASME Code,Section XI, appendix G, paragraph G-2110.
3.2.3.6 Flaw Density Section 8.3.2.2 and table 8-9 of the EPRI report state that a flaw density of 1.0 flaws per weld was used in the PFM analysis. In its safety evaluation dated October 19, 2023 for the Oconee pressurizers in the Duke Energy submittal, the NRC approved the use of a flaw density of 1.0 per weld in the PFM analysis. This flaw density is based on the NRC staffs determination as documented in the December 19, 2007, safety evaluation (ML073600374) for topical report BWRVIP-108NP-A, BWR Vessel and Internals Project: Technical Basis for the Reduction of Inspection Requirements for the Boiling Water Reactor Nozzle-to-Vessel Shell Welds and Nozzle Blend Radii, October 2018 (ML19297F806). Using this flaw density and estimated volumes of the subject pressurizer welds, the staff finds that the assumed flaw density for the subject pressurizer welds is reasonable. The staff confirmed that the materials and geometric criteria of the ANO-1 and ANO-2 pressurizer welds have met the applicability criteria of the EPRI report as shown in Attachments 1 and 2, respectively. As such, the NRC staff finds that use of the flaw density of 1.0 flaws per weld in the plant-specific PFM analysis of the ANO-1 and ANO-2 pressurizer welds is appropriate.
3.2.3.7 ISI Schedule and Examination Coverage Attachments 1 and 2 provide information on the inspection history of the subject pressurizer welds, which consists of the ISI schedule and examination coverage for ANO-1 and ANO-2, respectively. The licensees supplement, dated June 24, 2025, provides additional information on the inspection history.
ANO-1 Section 5.0 in the Enclosure states that for the ANO-1 pressurizer, PSI have been performed followed by ISI examinations over at least four complete 10-year ISI intervals. Inspection history for ANO-1 (including examinations performed to date, examination findings, inspection coverage, and relief requests) is presented in Attachment 1. As shown in Attachment 1, the lowest examination coverage was 37 percent of the required weld volume. The licensee evaluated this minimum coverage percentage in section 5.0 of the Enclosure and found it to be acceptable. The licensee has not identified any flaws that exceeded the ASME Code,Section XI, acceptance standards during any examinations as shown in Attachment 1.
ANO-2 Inspection history for ANO-2 (including examinations performed to date, examination findings, inspection coverage, and relief requests) is presented in Attachment 2. As shown in, the lowest examination coverage was 48 percent of the required weld volume. As a comparison, the NRC staff noted that examination coverage with a minimum 37.2 percent is acceptable as shown in the NRCs safety evaluation for the Salem pressurizer dated June 10, 2021. As shown in Attachment 2, the licensee has not identified any flaws in the ANO-pressurizer that exceeded the ASME Code,Section XI acceptance standards during any examinations.
Based on the above, the NRC staff finds that the inspection history of the ANO-1 and ANO-2 pressurizer welds is acceptable and that the PFM approach of the EPRI report sufficiently represents the subject ANO pressurizer welds with respect to the ISI schedule and examination coverage.
3.2.3.8 Other Considerations The PFM analysis of the EPRI report also involves other parameters such as initial flaw depth and length distribution, probability of detection, models, uncertainty, and convergence. The NRC staff noted that these considerations of the PFM analysis in the EPRI report do not depend on plant-specific information from the ANO pressurizer welds.
The NRC staff noted that initial flaw depth and length distribution do not depend on plant-specific information in the PFM analysis because the flaw distribution used was based on fabrication flaws instead of service-induced flaws. The staff noted that initial flaw depth is presented in the DFM analysis as discussed further in this safety evaluation. Probability of detection, which is associated with volumetric examinations, does not depend on plant-specific information because the corresponding welds in the pressurizer in different plants are subject to the same volumetric examination requirements of the ASME Code,Section XI. The models (e.g., the stress intensity factor models) used do not depend on plant-specific information because they are widely used models in PFM analyses. Uncertainty and convergence in the PFM analysis do not depend on plant-specific information because these are part of the overall PFM analyses that were addressed in the sensitivity studies and sensitivity analyses in the EPRI report. Because these considerations are not dependent on plant-specific information, the staff finds that the plant-specific ANO-1 and ANO-2 submittal is not being affected in terms of these considerations but these parameters are included in the PFM analysis.
3.2.3.9 PFM Results ANO-1 For the ANO-1 pressurizer, the licensee performed PSI examinations followed by examinations over four completed 10-year ISI intervals (ANO-1 and ANO-2 are currently in their fifth ISI interval). The licensee performed a plant-specific PFM analysis using the PSI/ISI scenario that included PSI plus four 10-year ISI examinations to be followed by a 30-year ISI deferral (PSI+10+20+30+40+70). This PSI/ISI scenario is consistent with the scenario evaluated in for the Oconee pressurizer, which is applicable to the ANO-1 pressurizer. In addition, geometry and operation conditions are similar between Oconee and ANO-1 pressurizers as discussed in the licensees submittal. Therefore, the NRC staff determined that the PFM results of the Oconee pressurizer in Attachment 5 are applicable to the ANO-1 pressurizer. The PFM evaluation in Attachment 5 shows that the probabilities of rupture and leakage for the Oconee pressurizer (that are applicable to the ANO-1 pressurizer) are significantly below the acceptance criterion of 1.0x10-6 failures per year after 80 years of operation.
discussed several sensitivity studies using various input parameters. For example, the fracture toughness can be as low as 72 ksiin before the acceptance criterion of 1.0x10-6 is reached after 80 years of operation. A stress multiplier of 1.4 can be applied to all the stress considered in the PFM analysis before the acceptance criterion is reached. By applying a stress multiplier of 1.1 and reducing the fracture toughness to 80 ksiin, the probabilities of rupture and leakage are all below the acceptance criterion of 1.0x10-6 after 80 years of plant operation.
As shown in table 10 of Attachment 5, the probabilities of rupture and leakage based on examination coverage as low as 25.2 percent of the weld volume are below the acceptance criteria of 1.0x10-6 after 80 years of operation by three orders of magnitude. The licensee stated that based on the PFM analysis, there is no difference in the probabilities of rupture and leakage between the proposed alternative inspection schedule and the required inspection schedule of the ASME Code,Section XI. The licensee concluded that this indicates that there is no change in risk from the current ASME Code,Section XI inspection schedule to that of the proposed alternative inspection schedule. Based on the analyses in Attachments 4 and 5, the NRC staff finds that the licensee has sufficiently demonstrated that the ANO-1 pressurizer welds with deferred examination would result in a PoF per year that is below the acceptance criterion of 1.0x10-6 failures per year.
ANO-2 As stated earlier, the licensee installed an ANO-2 replacement pressurizer in the second period of the third ISI interval in 2006 and performed a PSI at the time. The licensee also stated that it has completed one full ISI interval of examinations (during the fourth ISI Interval) since the pressurizer replacement. As such, the licensee analyzed the PSI/ISI scenario (PSI+10+40+70) for the ANO-2 replacement pressurizer as shown in table 4 of the Enclosure. This scenario was not specifically considered in the EPRI report PFM evaluations. Therefore, the licensee performed a plant-specific PFM evaluation for the ANO-2 pressurizer using this limiting PSI/ISI scenario as shown in the Enclosure. For the ANO-2 pressurizer, the licensee selected the critical Case ID PRSHC-BW-2C from the EPRI report with a combination of the dominant parameters (stress and fracture toughness). The licensee used a flaw density of 1.0 and a fracture toughness of 200 ksiin with a standard deviation of 5 ksiin. The licensee used a stress multiplier of 1.7 to demonstrate that probability of rupture or leakage will still be less than the acceptance criteria of 1.0x10-6 after 80 years of operation.
Based on the licensees plant-specific PFM analysis, the NRC staff finds that the licensee has sufficiently demonstrated that the ANO-2 pressurizer welds with deferred examination would result in a PoF per year that is below the acceptance criterion of 1.0 x10-6 failures per year.
3.2.4 Deterministic Fracture Mechanics Analysis The objective of the DFM analysis is to determine the length of time for the postulated flaw in the weld to become 100 percent through wall and to confirm the PFM analysis.
ANO-1 The ANO-1 DFM evaluation is based on the analysis performed for the Oconee pressurizer as presented in Attachment 5. The DFM analysis of the Oconee pressurizer in Attachment 5 is based on the DFM analysis in section 8.2 of the EPRI report. The design inputs used in the DFM evaluation are summarized in table 1 of Attachment 5. The NRC staff determined that the Oconee pressurizer and analyses in Attachment 5 are applicable to the ANO-1 pressurizer because of the geometric configuration, material selection, and transients of the ANO-1 pressurizer are within the bounds of the Oconee pressurizer. The licensee assumed an initial flaw size of 5.2 percent of the wall thickness, which is equivalent to the ASME Code,Section XI acceptance standard for these components with an associated crack aspect ratio (half crack length-to-crack depth) of 1.0. This crack shape results in a conservative initial stress intensity factor (K) at the deepest point of the crack. The licensee used the ASME Code,Section XI, appendix A, paragraph A-4300, FCG law in the flaw evaluation using the through-wall stress distributions from the stress analyses in Attachment 4. In addition, the licensee considered the weld residual stress from figure 8-1 of the EPRI report and the 30 ksi clad residual stress described in section 8.2.2.4 into the flaw evaluation. The fracture mechanics models described in section 8.2.2.4 of the EPRI report were used to calculate the time required for the postulated initial flaw to grow to a depth of 80 percent of the wall thickness (assumed to equate to leakage) or to the depth at which the allowable fracture toughness (upper shelf value of KIC equal to 106 ksiinch reduced by a structural factor of 2.0 for primary stresses and 1.0 for secondary stresses) was reached, whichever occurred first. The results of the DFM evaluation for the B&W pressurizer are summarized in table 4 of Attachment 5, which shows that given a postulated flaw in the weld, leakage will not occur in the Oconee pressurizer (thus not occur in the ANO-1 pressure) for more than 80 years. The NRC staff determined that (1) the DFM analysis in demonstrates that the structural integrity of the ANO-1 pressurizer will be maintained for more than 80 years, (2) the DFM analysis supports the PFM analysis conclusion that the PoF for the ANO-1 pressurizer will be below 1.0 x10-6 failures per year.
ANO-2 The ANO-2 DFM evaluation is based on the DFM analysis in section 8.2 of the EPRI report.
Based on the NRCs safety evaluation for the Salem pressurizer dated June 10, 2021, the NRC staff determined that the EPRI report is applicable to the ANO-2 pressurizer because the geometric configuration, material selection, and transients of the ANO-2 pressurizer are within the bounds of the generic pressurizer analyzed in the EPRI report. The licensee postulated initial flaw size (5.2 percent of the wall thickness), with an associated crack aspect ratio (half crack length-to-crack depth) of 1.0. The licensee also used the same FCG rate from the ASME Code,Section XI, appendix A, paragraph A-4300 for both ANO pressurizers. The leakage occurs when the postulated initial flaw grows to a depth of 80 percent of the wall thickness.
The NRC staff determined that the results of the DFM analysis in the EPRI report are applicable to the ANO-2 pressurizer due to the similar geometry, material properties, and loading conditions. In the DFM analysis in section 8.2 of the EPRI report, all analyzed locations exhibited flaw growth times exceeding 80 years before reaching a through-wall depth indicative of potential leakage (i.e., it would take more than 80 years for the postulated flaw to reach a depth indicative leakage). No locations reached an applied stress intensity factor greater than an allowable stress intensity factor value of 100 ksiin (a mean fracture toughness of 200 ksiin with a safety factor of 2). Thus, the staff determined that (1) the DFM analysis of the EPRI report demonstrates that the structural integrity of the ANO-2 pressurizer will be maintained for more than 80 year, (2) the DFM analysis supports the PFM analysis conclusion that the PoF for the ANO-2 pressurizer will be below 1.0 x10-6 failures per year.
3.2.5 Performance Monitoring The NRC staff did not reach the same conclusion as the licensee regarding the applicability of the PFM results to justify eliminating inspections for the remaining fifth and sixth ISI intervals.
Specifically, the staff determined that the licensees PFM analysis does not account for the combined effect of the most significant parameters or the additional uncertainties associated with low probability events. More significantly, the staff considers the licensees conclusion to be a risk-based approach, which is inconsistent with NRC policy that calls for risk insights to be considered together with other factors rather than sole reliance on risk-based approaches. The NRC policy is based on a risk-informed approach, not a risk-based approach. The staff determines that post-fabrication examinations are critical in supporting necessary performance monitoring goals including monitoring and trending, bounding uncertainties, validating/confirming analytical results, and providing timely means to identify novel and/or unexpected degradation. The staff finds that the licensee should include adequate performance monitoring as part of the basis for its proposed alternatives.
The NRC staff noted that performance monitoring, such as ISI programs, is a necessary component described by the NRC five principles of risk-informed decision making. Analyses, such as PFM analysis, combine with performance monitoring to provide a mutually supporting and diverse basis for facility condition and maintenance that is within its licensing basis. The staff determined that an adequate performance monitoring program must provide direct evidence of the presence and extent of degradation, validation of continued appropriateness of associated analyses, and a timely method to detect novel/unexpected degradation. The staff described these characteristics at various public meetings (ML22060A277, ML23033A667, and ML23114A034).
The ASME Code requires examination of the ANO-1 and ANO-2 pressurizer welds during the fifth and sixth ISI intervals. Therefore, under the ASME Code,Section XI, the licensee is required to examine equivalent of four pressurizers as shown in table 1 below.
Table 1: ASME Code Required Number of Pressurizers to be Examined in Fifth and Sixth Intervals Site
- of Nuclear Units
- of Pressurizer Required to be Examined per Unit per Interval
- of ISI Intervals (i.e., 5th and 6th Intervals)
ASME Code Required Exam =
Units x Required Pressurizer Exam per Unit x Intervals ANO-1 1
1 2
2 ANO-2 1
1 2
2 Total 4
Based on its statistical analysis, the NRC staff finds that inspection of 25 percent of the required pressurizer population is acceptable as discussed in the NRCs safety evaluation dated October 19, 2023for the review of the Duke Energy submittal. This means that the licensee could inspect one pressurizer, instead of four pressurizers, during the combined fifth and sixth ISI intervals (4 x 0.25 = 1.0) for both ANO-1 and ANO-2.
The NRC staff notes that the ASME Code,Section XI, table IWB-2500-1, requires the licensee to inspect ten welds of the ANO-1 pressurizer and seven welds of the ANO-2 pressurizer during each 10-year ISI interval, respectively. As shown in section 5.1.6 of the Enclosure, the licensee has inspected five welds in the ANO-1 pressurizer in the fifth ISI interval. The licensee has inspected one weld in the ANO-2 pressurizer during the fifth ISI interval. As part of the proposed alternative, the licensee proposed to inspect one weld,05-002 (Examination Category B2.11), in the ANO-2 pressurizer in the sixth ISI interval. In its supplement dated June 24, 2025, the licensee proposed to examine two B3.110 welds in the ANO-2 pressurizer in the sixth ISI interval in addition to the proposed examination of weld 05-002 in the sixth ISI interval. With these proposed three weld examinations and one weld that was examined in the ANO-2 pressurizer in the fifth ISI interval, the licensee will have examined a total of four welds in the ANO-2 pressurizer for the fifth and sixth ISI intervals. The staff performed the following assessment as shown in table 2 below.
Table 2: Number of Pressurizer Equivalent Examinations for Fifth and Sixth Interval Unit ASME Code Required Number of Pressurizer Welds to be Examined Licensee Proposed to Examine Number of Pressurizer Welds in 5th and 6th Intervals Pressurizer Equivalents =
Proposed Exams /
Required Exams ANO-1 10 5
0.5 ANO-2 7
4 0.57 Total 1.07 Under the proposed alternative, the licensee would have examined 1.07 pressurizer Equivalent, which is greater than the NRC staff permitted examination of 1.0 pressurizer. Therefore, the staff finds that the licensee-proposed performance monitoring of the ANO-1 and ANO-2 pressurizers is acceptable.
3.2.6 Degradation Management The NRC staff evaluated how the licensee manages potential degradation in the subject ANO pressurizer welds that exceed the acceptance standards of the ASME Code,Section XI, IWB-3500 to ensure that the subject ANO pressurizer welds are adequately maintained.
Section 5.1.6 in the Enclosure states that the performance monitoring plans for the ANO-1 and ANO-2 pressurizers will ensure that assumptions of the PFM analyses remain valid, and that novel or unexpected degradation is detected and dispositioned in a timely fashion. If indications are detected that exceed the applicable ASME Code,Section XI, acceptance standards contained in IWB-3500, then the indications will be addressed as required by the ASME Code,Section XI, and the Entergy Corrective Action Program (CAP). The licensee stated that the additional examination and successive inspection requirements of ASME Code,Section XI, also apply during the current outage. The number of additional exams shall be the number required by the ASME Code,Section XI, IWB-2430.
In addition to the inspection requirements of the ASME Code,Section XI, the licensee uses its CAP to review and evaluate industry operating experience (OE) to determine the appropriate actions required based upon the specific OE. The licensee stated that if industry OE indicates that a new or novel degradation mechanism is possible in pressurizer circumferential and longitudinal shell-to-head welds and nozzle-to-vessel welds, the appropriate examinations will be performed or considered to ensure that no such mechanism is occurring in the ANO pressurizer welds.
In its supplement dated June 24, 2025, the licensee stated that if a flaw is found as a part of the performance monitoring plan, it will enter the adverse condition into the ANO CAP and expand scope to the other unit for the examination category and item number, as applicable, within one to two refueling outages. The licensee stated that scope expansion will be performed in accordance with the ASME Code,Section XI, IWB-2430 and IWB-3500, as applicable The NRC staff has determined that if an unacceptable flaw is detected in the subject ANO pressurizer welds, the licensee will inspect the welds in other units in the proposed alternatives within first to second scheduled refueling outages of discovery of the flaw. The staff finds that the proposed scope expansion inspection and associated timeline are consistent with the staff position and is, therefore, acceptable.
3.2.7 Summary In summary, based on the PFM and DFM analyses provided in the licensees submittal and the adequate performance monitoring plan, the NRC staff determined that inspections for the ANO-1 and ANO-2 pressurizer welds could be deferred (except the welds that the licensee has proposed to examine) during the fifth and sixth ISI intervals while maintaining an acceptable level of plant quality and safety.
4.0 CONCLUSION
Based on information submitted, the NRC staff has determined that the licensees Alternative Requests ANO1-ISI-24-01 and ANO2-ISI-24-01, as supplemented by letter dated June 24, 2025, provide an acceptable level of quality and safety. Accordingly, the staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1). Therefore, the staff authorizes the use of Alternative Request ANO1-ISI-24-01 at ANO-1 up to May 20, 2034, and Alternative Request ANO2-ISI-24-01 at ANO-2 up to July 17, 2038.
All other ASME Code,Section XI, requirements for which relief was not specifically requested and approved in the proposed alternative requests remain applicable, including third party review by the Authorized Nuclear Inservice Inspector.
Principal Contributors: Eric Palmer, NRR John Tsao, NRR Date: September 26, 2025
- via eConcurrence NRR-028 OFFICE NRR/DORL/LPL4/PM*
NRR/DORL/LPL4/LA*
NRR/DNRL/NVIB/BC*
NAME MChawla PBlechman ABuford DATE 9/22/2025 9/22/2025 9/24/2025 OFFICE NRR/DORL/LPL4/BC NAME TNakanishi DATE 9/26/2025