ML21264A535

PWROG-19047-NP-A, Rev 0, North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis

ML21264A535
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Site:	North Anna, 99902037
Issue date:	09/30/2021
From:	Hall G Framatome, PWR Owners Group, Westinghouse
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML21264A532	List: ML21264A533 ML21264A535 ML21264A536 ML21264A537
References
OG-21-177, PA-MSC-1481, Rev 3 PWROG-19047-NP-A
Download: ML21264A535 (92)

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PRESSURIZED WATER REACTOR OWNERS GROUP Westinghouse Proprietary Class 2 PWROG-19047-NP-A Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis Materials Committee PA- MSC-1481, R3 September, 2021

@ Westinghouse framatome

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY PWROG-19047-NP-A Revision 0 North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis PA- MSC-1481, R3 Gordon Z. Hall

• Structural Design and Analysis September, 2021 Reviewer: James Andrachek*

PWR Owners Group PMO Reviewer: Ashok D. Nana Framatome, Component Analysis and Fracture Mechanics Approved: Stephen P. Rigby*, Manager Structural Design and Analysis Approved: Jim Molkenthin*, Program Director PWR Owners Group PMO

• Electronically approved records are authenticated in the electronic document management system.

Westinghouse Electric Company LLC 1000 Westinghouse Drive Cranberry Township, PA 16066, USA

© 2021 Westinghouse Electric Company LLC All Rights Reserved Framatome Inc.

3315 Old Forest Road Lynchburg, VA 24501 PWROG-19047-NP-A_Revision_0 (2).docx-090721

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY iii NON-PROPRIETARY INFORMATION FINAL SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR THE PRESSURIZED WATER REACTOR OWNERS GROUP TOPICAL REPORT PWROG-19047-P/NP. REVISION 0 1 "NORTH ANNA UNITS 1 AND 2 REACTOR VESSELS LOW UPPER-SHELF FRACTURE TOUGHNESS EQUIVALENT MARGIN ANALYSIS" EPID: L-2020-TOP-0028 NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY iv NON-PROPRIETARY INFORMATION TABLE OF CONTENTS

3.0 TECHNICAL EVALUATION

.. ........ .. .. .. .............. ....... .. .. .. .............. .... ........ ................... . 3.1 Overview of PWROG-19047-P/NP .. .. .. .. ... .. .. .... .. .. .. .. ...... ......... .. .. .. .. .. .. ..... .............. .. .... 3.2 Staff Evaluation ............. ........ ....................... .... .......... .... ....................... .... .... ............... 3.2.1 lnputs ......... ....................... .................. ....................... .... .... ................... .... .... .... ........... 3.2.2 Applicability of the J-lntegral Resistance Models ..... .. .. .... .. ..... .... ........ ................... ...... 3.2.3 Consistency with Appendix K to Section XI of the ASME Code ....... ........... .. ................ 3.2.4 Selection of Transients .. .. .... ..... .. .. ... ..... ... .. .. ..... ....... ...... .. ... .... ............... ... ..... ... ... .. .. .. 3.2.5 Evaluation and Acceptance Criteria Per ASME Code ,Section XI , Appendix K ...... ....

4.0 CONCLUSION

S .. .. ...... ........ .......... ... .. ......... .... ........ ... .. ............. ........... ... ............. ..... 5.0 CONDITIONS, LIMITATIONS, AND/OR ACTION ITEMS .. ............. .. .. .. .. .. .. .. ... ... .... ...

6.0 REFERENCES

..... ...... ......... .... .................. ... .. .. ... ...... .... .... ......... ...... .... .... .... ... ........ .. ENCLOSURE - COMMENT DISPOSITION TABLE ... ..... ..... .. .. .. ... .. .. .... .. .. .. .. ............... .. .. .. .. NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY v NON-PROPRIETARY INFORMATION

1.0 INTRODUCTION

By letter dated May 27, 2020 (Ref. 1), as supplemented by letter dated November 19, 2020 (Ref. 2), the Pressurized Water Reactor Owners Group (PWROG) submitted Topical Report (TR) PWROG-19047-P/NP, Revision (Rev.) 0, "North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis" (Ref. 3), to the U.S. Nuclear Regulatory Commission (NRC) for review and approval.

The purpose of this TR is to document the equivalent margins analysis (EMA) for the North Anna Power Station, Units 1 and 2 (North Anna) reactor vessel (RV) inlet and outlet nozzle welds, nozzle forgings, and nozzle belt forgings (a.k.a., upper shell forgings). These locations were chosen for their upper-shelf energy (USE) potentially falling below the 50 foot- pound (ft-lb) limit at 80-years (72 effective full power year (EFPY)) for subsequent license renewal (SLR) . In accordance with the requirements of Appendix G, "Fracture Toughness Requirements," to Title 10 of the Code of Federal Regulations (10 CFR) Part 50 as listed in Paragraph IV.A.1.a, the RV beltline materials must maintain Charpy USE throughout the life of the vessel of no less than 50 ft-lb (68 J), unless it is demonstrated in a manner approved by the NRC, that lower values of Charpy USE will provide margins of safety against fracture equivalent to those required by Appendix G to Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) (Ref. 4).

The EMA documented in the TR for the nozzle and upper shell forgings uses the multivariable model for RV base metal reported in NUREG/CR-5729, "Multivariable Modeling of Pressure Vessel and Piping J-R Data" (Ref. 5). Although the nozzle-to-shell welds are projected to have USE greater than 50 ft-lbs at 72 EFPY, they are evaluated proactively in this EMA for asset management consideration. The EMA documented in the TR for the Rotterdamsche Droogdok Maatschappij (Rotterdam) welds utilizes the Babcock & Wilcox Owners Group (B&WOG)

J-integral resistance (J-R) Model 68 reported in Appendix A of BAW-2192, Revision 0, Supplement 1 P/NP-A, Rev. 0, "Low Upper-Shelf Toughness Fracture Mechanics Analysis of Reactor Vessels of B&W Owners Reactor Vessel Working Group for Levels A & B Service Loads" (Ref. 6). The justification for using the B&WOG Model 68 for the North Anna Rotterdam welds is addressed in BAW-2192, Supplement 2P/NP-A, Rev. 0, "Low Upper-Shelf Toughness Fracture Mechanics Analysis of Reactor Vessels of B&W Owners Reactor Vessel Working Group for Levels A & B Service Loads" (Ref. 7) .

2.0 REGULATORY EVALUATION

The regulations in Appendix G to 10 CFR Part 50 specifies fracture toughness requirements for ferritic materials of pressure-retaining components of the reactor coolant pressure boundary of light water nuclear power reactors to provide adequate margins of safety during any condition of normal operation, including anticipated operational occurrences and system hydrostatic tests, to which the pressure boundary may be subjected over its service lifetime. The NRC staff reviews licensee evaluations to ensure that they provide a realistic or conservative assessment of the RPV such that it can be demonstrated that the licensee complies with these requirements .

Specifically, 10 CFR Part 50, Appendix G, Paragraph IV.A.1.a requires RV beltline materials to have a minimum USE value of 75 ft-lb in the unirradiated condition, and to maintain a minimum USE value above 50 ft-lb throughout the licensed period of operation of the facility, unless it can be demonstrated through analysis (i.e., EMA) that lower values of USE would provide acceptable margins of safety against fracture equivalent to those required by Appendix G to NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY vi NON-PROPRIETARY INFORMATION Section XI of the ASME Code . The rule also mandates that the methods used to calculate USE values must account for the effects of neutron irradiation on the USE values for the materials and must incorporate any relevant RV surveillance capsule data that are reported through implementation of a plant's RV material surveillance program.

For evaluations of low-upper shelf toughness, NUREG-0800 Section 5.3.2, "Pressure-Temperature Limits, Upper Shelf Energy, and Pressurized Thermal Shock" (Ref. 8) states that in addition to the ASM E Code, Regulatory Guide (RG) 1.161 , "Evaluation of Reactor Pressure Vessels with Charpy Upper-Shelf Energy Less Than 50 ft-lb" (Ref. 9) provides an acceptable methodology for the performance of analyses intended to meet the provisions for additional analysis specified in Appendix G to 10 CFR Part 50 Paragraph IV.A. 1.a.

In accordance with 10 CFR 54.3, "Requirements for Renewal of Operating Licenses for Nuclear Power Plants," under the current licensing basis (CLB) USE is considered a time-limited aging analysis (TLAA). The "Standard Review Plan for Review of Subsequent License Renewal Applications for Nuclear Power Plants Final Report," NUREG-2192, provides guidelines for review of the USE TLAA in Section 4.2.2.1.2.

RG 1.161 provides guidance for acceptable methods of evaluating low USE , and states that the analytical methods described in Appendix K of Section XI of the ASME Code (Appendix K),

provide acceptable guidance for evaluating reactor pressure vessels when the Charpy USE falls below the 50 ft-lb limit of Appendix G to 10 CFR Part 50. However, Appendix K does not provide detailed information on the selection of transients and gives very little details on the selection of material properties. However, RG 1.161 provides guidance for selecting transients for Service Level A , B, C, and D conditions , and models for determining the J-R curves for various classes of RV materials, including Linde 80 welds.

The NRC staff considered 10 CFR Part 50, Appendix A, "General Design Criteria for Nuclear Power Plants," when evaluating the TR with respect to General Design Criteria (GDC) . The N RC staff review of the fluence assumptions was performed in consideration with the requirements contained in GDC 14, "Reactor Coolant Pressure Boundary;" GDC 30, "Quality of Reactor Coolant Pressure Boundary;" and GDC 31, "Fracture Prevention of Reactor Coolant Pressure Boundary." These GDCs require the design , fabrication , and maintenance of the reactor coolant pressure boundary with adequate margin to assure that the probability of rapidly propagating failure of the boundary is minimized . In particular, GDC 31 explicitly requires consideration of the effects of irradiation on material properties.

RG 1.190, "Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence" (Ref. 10), provides guidance on methods for determining reactor pressure vessel fluence that are acceptable to the NRC staff, based on the requirements identified above.

3.0 TECHNICAL EVALUATION

This technical evaluation section documents the NRC staff's evaluation of the TR against the relevant criteria identified in Section 2.0 above.

NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY vii NON-PROPRIETARY INFORMATION 3.1 Overview of PWROG-19047-P/NP The TR covers the following major topics:

Section 1.0 discusses the scope and purpose of the TR. Specifically, the TR documents the EMA for the North Anna RV inlet and outlet nozzle Rotterdam welds, nozzle forgings , and nozzle belt forgings. These locations were chosen for USE potentially falling below the 50 ft-lb limit at 80-years (72 EFPY) for SLR .

Section 2.0 of the TR addresses regulatory requirements and ASME Code requirements.

Specifically, Appendix G to 10 CFR Part 50 Paragraph IV.A.1 specifies the RV Charpy USE requirements. TR Section 2.2 states the EMAs are performed in accordance with Appendix K of the 2013 Edition of Section XI of the ASME Code (i.e., an edition incorporated by reference in 10 CFR 50 .55a and Appendix G) , and confirms that the material properties used in this analysis are based on the original RV construction code , ASME Boiler and Pressure Vessel Code ,

Section Ill, 1968 Edition, with Addenda up to and including the Winter of 1968.

Section 3.0 of the TR provides the inputs for the EMAs and a description of the RVs for North Anna . Specifically, the finite element stress model and analysis ; and the J-R models used to address the RV inlet and outlet nozzle Rotterdam welds, nozzle forgings, and nozzle belt forgings were described.

Section 4.0 of the TR describes the fracture mechanics evaluation method used, which is in accordance with Appendix K. Section 4.0 also provides the detailed results of the fracture mechanics evaluation, which included two analyses per component: an evaluation of flaw extension and an evaluation of flaw stability.

Section 5.0 of the TR also contains the summary and conclusions. The PWROG concluded that all components assessed by the EMAs for North Anna met the acceptance criteria of Appendix K for Service Level A and B loadings, and Service Level D loadings. The applicant further concluded that the EMAs in this TR demonstrate that the North Anna RV nozzle-to-shell welds, nozzle forgings, and upper shell forgings were evaluated for equivalent margins of safety per ASME Code Section XI, and that the flaw extension and stability criteria of Appendix K were satisfied.

NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY viii NON-PROPRIETARY INFORMATION 3.2 Staff Evaluation The NRC staff's review focused on :

Verification that the EMAs for North Anna were performed in accordance with the Appendix K to Section XI of the ASME Code Verification that the EMA results for North Anna satisfy the acceptance criteria in Appendix K to Section XI of the ASME Code 3.2.1 Inputs 3.2.1 .1 Material chemistry. RT NPI* and Upper-Shelf Energy Value Section 3.2 of the TR states that "the maximum reported copper content and the fluence value at the nozzle-to-shell weld is utilized" as summarized in Table 3-3 of the TR . In its RAI responses dated November 19, 2020, the PWROG explained that the copper content value is the generic value in RG 1.99, Rev . 2, "Radiation Embrittlement of Reactor Vessel Materials" (Ref. 11) , because the weld heat and type for these nozzle-to-shell welds could not be determined, only that these welds were fabricated by Rotterdam. Consistent with the PWROG-17090-NP-A, "Generic Rotterdam Forging and Weld Initial Upper-Shelf Energy Determination" (Ref. 12), when the weld heat and type are not known for a Rotterdam fabricated weld, the generic values of 0.35% and 1.13% from RG 1.99, Rev. 2 can be used for copper content and nickel content, respectively . Thus, the staff finds the use of 0.35% and 1 .13% for copper content and nickel content in the TR to be acceptable. Furthermore, the PWROG clarified that the RTNor value of 208.3°F is applicable to the inlet nozzle to upper shell welds and outlet nozzle to upper shell welds and discussed how it calculated the Adjusted Reference Temperature (ART) . Based on its review, the staff confirmed that the RTNoT(uJ values, and material chemistry values (i.e ., copper and nickel) for these components are consistent with the CLB for North Anna and PWROG-17090-N P-A, respectively. Furthermore , the staff confirmed that the ART value of 208.3°F used in the TR was determined to be consistent with the RG 1.99, Rev 2.

Section 3.2 of the TR provides the basic form of J-R as expressed in NUREG/CR-5729, and RG 1.161 . Furthermore , the TR provides the different parameters , variables and assumed values used in the EMAs for North Anna. In its RAI responses dated November 19, 2020, the PWROG explained that the 80-year USE values for North Anna are documented in WCAP-18364-NP, Rev. 1, "North Anna Units 1 and 2 Time-Limited Aging Analysis on Reactor Vessel Integrity for Subsequent License Renewal (SLR)" (Ref 13), and also provided the Charpy values used in the TR for the nozzle and intermediate forgings . The PWROG also confirmed in its supplement that the input parameters represent weak orientation material properties in all cases, which the staff finds to be a conservative approach . The staff reviewed the 80-year USE values for the North Anna RV inlet and outlet nozzle-to-shell welds , nozzle forgings , and intermediate shell forging , in WCAP-18364-N P for the purposes of verifying that the reference of these values were appropriate in the TR. Based on its review, the staff finds the 80-year USE values for the North Anna RV inlet and outlet nozzle-to-shell welds, nozzle forgings, and intermediate shell forging were calculated consistent with applicable regulations in Appendix G to 10 CFR Part 50 and guidance in RG 1.99, Rev. 2. Additionally, the staff confirmed that the Charpy values used in the TR to calculate J-R curves for the nozzle and intermediate forgings NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY ix NON-PROPRIETARY INFORMATION were conservative compared to the 80-year USE values for the North Anna, nozzle forgings and intermediate shell forging .

3.2.1 .2 Neutron Fluence Values Section 3.2 of the TR indicates that the neutron fluence value at the nozzle-to-shell weld is summarized in Table 3-3 of the TR. In its RAI responses dated November 19, 2020, the PWROG clarified that revised fluence values were generated and documented in WCAP-18015-NP, Rev. 2 (Ref. 14). This document was submitted in support of the NRC staff review of a change to the North Anna , Units 1 and 2 surveillance capsule withdrawal schedule (the staffs assessment is documented in Ref. 15). The methods used to calculate the fluence are consistent with those described in Chapter 2.2 of WCAP-14040-A, Rev. 4, "Methodology Used to Develop Cold Overpressure Mitigating System Setpoints and RCS Heatup and Cooldown Limit Curves" (Ref. 16). In the surveillance capsule withdrawal schedule review, the NRC staff determined that the fluence estimates contained therein were acceptable, because the methods used to calculate the fluence were adherent to RG 1.190, and thus consistent with GDC 14, 30, and 31 . This conclusion applies to the fluence estimates, insofar as they support the additional evaluations provided in the TR .

In the safety evaluation referenced above, the NRC staff noted that the application of the fluence methods to RV components that are significantly above or below the core, i.e., nozzle elevations, would require more detailed evaluation . In that review, the NRC staff considered various contributors to the generic uncertainty estimate provided in WCAP-14040-A that would likely increase as a result of the increased transport distance to the nozzle elevations, and determined that significant increases could be accommodated and the overall uncertainty could still remain within the +/-20-percent criterion specified in RG 1.190.

In its RAI responses dated November 19, 2020, the PWROG provided additional justification for the treatment of the fluence values assumed for the North Anna, Units 1 and 2 RV inlet and outlet nozzles . Among other things, the licensee stated:

• The maximum projected fluence values of the North Anna RV inlet/outlet nozzles ... could increase by 60% before exceeding the fluence value utilized in the [equivalent margins analysis (EMA) for subsequent license renewal].

• ... the limiting [upper shelf energy] nozzle for both Units 1 and 2 ... would need to increase by a factor of greater than 4 prior to reaching the fluence utilized in the EMA.

• .. . the maximum projected fluence values of the North Anna inlet and outlet nozzle-to-shell welds would need to increase by 3 times the current value before exceeding the fluence value utilized in the EMA for SLR .

The additional information indicates that the nozzle fluence values assumed in the EMA bound, with substantial margin, the fluence estimates that were determined using the discrete ordinates transport methods to support the SLR. This margin provides assurance that, even if the uncertainty associated with the nozzle fluence estimates were to exceed +/-20-percent by a modest amount, the EMA would remain bounding for those components. Based on this consideration and on the previous staff determination considering the acceptability of the fluence values documented in WCAP-18015-NP, the NRC staff determined that the fluence assumptions in the TR are acceptable.

NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY x NON-PROPRIETARY INFORMATION 3.2.1 .3 Mechanical Properties Section 2.2 of the TR indicates that the material properties used in the EMAs are based on the original RV construction code , ASME Boiler and Pressure Vessel Code, Section Ill ,

1968 Edition , with Addenda up to and including the Winter of 1968. Specifically, Section 3.1 of the TR provides the material properties of SA-508 Class 2 used for the RV shell and nozzle forging base metal, and the material properties for Type 304 stainless steel used for the cladding . The PWROG indicated that the nozzle-to-shell weld mechanical properties were assumed to be identical to the forging material for the purpose of stress analysis. The staff noted that this assumption is typical of finite element analysis (FEA) and is reasonable because the objective of the FEA in the TR was not to determine residual stress due to the welding process of the nozzle-to-shell welds. The staff reviewed Updated Final Safety Analysis Report (UFSAR) (Ref. 17) Section 5.4.3.6 and UFSAR Tables 5.2-3, 5.2-22, 5.2-26, and 5.2-27 and confirmed that the base metal and cladding materials are consistent with those addressed in the TR ; thus, the staff finds the material properties used in the TR are appropriate for North Anna .

3.2.2 Applicability of the J-lntegral Resistance Models K-3000 of Appendix K does not contain a specific model for determining the J-R material curve .

Instead, K-3300 of Appendix K specifies that the J-R curve must be generated based on accepted test procedures, a database obtained from the same class of material, or an indirect method provided the method is justified for the material. The staff's review of the applicability of the J-R model used for the RV nozzle-to-shell welds and RV nozzle and upper shell forging is documented below.

RV Nozzle-to-Shell Welds Section 3.2 of the TR states that the nozzle-to-shell welds were fabricated by Rotterdamsche Droogdok Maatschappij and that the nozzle weld EMA utilizes the B&VVOG J-R model 6B reported in BAW-2192, Rev . 0, Supplement 1 P-A, Rev . 0, Appendix A. The PWROG explained that the justification for the use of Model 6B for the North Anna nozzle-to-shell welds is provided in BAW-2192, Rev. 0, Supplement 2P-A, Rev. 0.

Based on its review of BAW-2192, Rev . 0, Supplement 2P-A, Rev. 0, including the data set used to develop the Model 6B curve and the new Rotterdam J-R data in the report, the staff determined that the PWROG J-R Model 6B: (a) bounds most of the original and new data used in its development, and (b) bounds all of the new Rotterdam J-R data provided in the report (see Ref. 5) . Thus, the staff finds the use of the Model 6B curve acceptable for use in the 80-year EMAs for the North Anna Rotterdam weld material within the limits of the B&WOG Model 6B explanatory variables. The staff noted the application of the Model 6B curve for the 80-year EMA for the North Anna Rotterdam weld material is dependent, in part, on the acceptability and consistency with the plant's CLB of the material chemistry values (i.e., Cu and Ni values) used in the EMA for each RV weld material.

The staffs review of the acceptability and consistency with the plant's CLB of material chemistry values used in the TR for nozzle-to-shell welds for North Anna , is documented in Section 3.2.1.1 of this SE. Based on the staff's review, the staff noted the material chemistry values used in the TR for nozzle-to-shell welds are within the B&WOG Model 6B explanatory variables for copper content; thus, the staff finds that for the inlet and outlet nozzle-to-shell welds at North Anna NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xi NON-PROPRIETARY INFORMATION (a) the use of the Model 6B curve to be appropriate and acceptable , and (b) K-3300 of Appendix K has been appropriately addressed.

RV Nozzle and Shell Forgings Section 3.2 of the TR states that the J-R curves for the RV nozzle and shell forgings were developed in accordance with Charpy model without fluence in Table 11 of NUREG/CR-5729.

The PWROG explained that this Charpy model is the same model described in Section 3.3 of RG 1.161 and is applicable to the North Anna nozzle and shell forgings because they are bounded by the range of explanatory variables (fluence, copper content, etc.) used to develop the J-R model.

In its RAI responses dated November 19, 2020, the PWROG clarified that the Charpy model without fluence in Table 11 of NUREG/CR-5729 is applicable to the North Anna nozzle and shell forgings since this J-R model was validated against representative Rotterdam forgings with measured J-R data. Furthermore , in its supplement, the PWROG provided a comparison of measured test data from Rotterdam forgings to the Charpy model in Table 11 of NUREG/CR-5729 used in the TR . The staff noted that the Charpy model used in the TR was representative of the measured test data from these Rotterdam forgings. Based on its review, the staff finds (1) K-3300 of Appendix K has been addressed and (2) the use of the Charpy model without fluence in Table 11 of NUREG/CR-5729 for the nozzle and shell forgings at North Anna to be appropriate because the material fabrication of these components are applicable to the database of materials used to develop this J-R model.

3.2.3 Consistency with Appendix K to Section XI of the ASME Code Nozzle-to-Shell Welds and Upper Shell Forgings Section 4.1.1 of the TR explains that for axial or circumferential flaws the stress intensity factor (SIF) due to radial thermal gradients can be calculated per K-4210(c) of Appendix K. However, since the thermal stresses are based on a FEA, the PWROG explained that the procedure in A-3320 of 2013 Edition of Section XI of the ASME Code were modified and used to calculate the SIFs. The PWROG explained that this modified approach used in the TR is consistent with the methods in the 2015 Edition of Section XI of the ASME Code (i.e ., A-3212 and A-3411 (c)) .

The staff noted that the 2015 Edition of Section XI of the ASM E Code has been incorporated by reference in to 10 CFR 50.55a , "Codes and Standards;" thus, the staff finds the use of these modified procedures used in the TR for the nozzle-to-shell welds and upper shell forging to be acceptable .

The PWROG stated that the method described in A-3200 of Section XI of the ASM E Code, including crack face pressure, with an actual FEA pressure stress profile will be used for the SIF calculations. The staff finds the use of procedures consistent with A-3200 of Section XI of the ASME Code for the nozzle-to-shell welds and upper shell forging to be acceptable .

Nozzle Forging Section 4.1.1 of the TR states that the nozzle corner is the bounding location for the nozzle forging and the nozzle corner flaws are considered using the quarter circular crack as shown in Figure 4-1 of the TR . Furthermore , the PWROG provided the closed form solutions to compute the crack tip K, values. The staff finds selecting the nozzle corner to be the bounding location NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xii NON-PROPRIETARY INFORMATION for the nozzle forging to be reasonable because of the increased stress levels at this location caused by the structural discontinuities of the nozzle corner. The staff also finds the PWROG's use of closed form solutions for the nozzle forging in the TR to be acceptable because they are consistent with procedures for determining SIFs in Section XI of the ASME Code that have been incorporated by referenced in 10 CFR 50.55a .

3.2.4 Selection of Transients Appendix K contains acceptance criteria and evaluation procedures for determining acceptability for operation of RVs when the vessel metal temperature is in the upper shelf range. The methodology is based on the principles of elastic-plastic fracture mechanics. Flaws are to be postulated in RV locations of predicted low USE, and the applied J-integral for these flaws are to be calculated and compared with the J-R curve of the material to determine acceptability. K-1100 of Appendix K indicates that all transients for the RV are to be considered . Further, Section 4 of RG 1.161 provides additional guidance for the selection of Service Level C and D transients. The staff's review of the transients selected in the TR for (a)

Service Level A and B Transients and (b) Service Level C and D Transients are documented below.

Selection of Service Level A and B Transients Section 2.1 of the TR indicates that the applicant selected the cooldown transient for North Anna with a constant pressure of 2750 psia assumed throughout the transient, which bounds all Levels NB conditions and is consistent with and based on the Appendix K, 100° F/hour cooldown rate guidance coincident with the use of a high pressure value .

In its RAI responses dated November 19, 2020, the PWROG confirmed that it considered the design transients defined by the ASME Section Ill Certified Design Specification , specifically the Service level NB (i.e ., normal/upset conditions) in UFSAR Table 5.2-4. The PWROG explained that the cooldown transient was chosen to bound all Levels NB service loading conditions, and a constant accumulation pressure of 2750 psia was used (i .e., 1.1 times design pressure) per K-1300 and K-4220 of Appendix K. Furthermore, staff noted that the plant cooldown transient with a 100°F/hour cooldown rate is consistent with K-421 0(c) of Appendix K. The staff finds the TR adequately addressed K-1100 of Appendix K to Section XI of the ASME Code because the CLB design transients at North Anna were assessed and the transient selected is consistent with the guidelines in Appendix K.

Selection of Service Level C and D Transients Section 2.1 of the TR indicates that the Level CID transient selection is based on the guidance in RG 1.161 and explained that the Level D transient is the steam line break (SLB).

Furthermore, Section 4.1 of the TR indicates that only the SLB transient is specified for Level D conditions.

In Section 4.1 of the TR and in its RAI responses dated November 19, 2020, the PWROG states that there is no applicable emergency (Level C) transient defined in the Westinghouse RV design specification . The staff reviewed UFSAR Table 5.2-4 Section and confirmed there are no applicable emergency (Level C) transient as part the CLB for North Anna . Thus, the staff finds that it is appropriate that Level C transients need not be addressed in the TR .

NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xiii NON-PROPRIETARY INFORMATION The staff noted that K-1100 of Appendix K states, in part, that "[a]II specified design transients for the reactor vessel shall be considered ." The staff reviewed North Anna UFSAR Table 5.2-4 and noted that beyond the "steam pipe break" transient there are additional Service Level D conditions (i.e. , Faulted Conditions) that are applicable to the CLB for North Anna , such as the "Main reactor coolant pipe break" and "Design-basis earthquake ." Section 4 of RG 1.161 states that selection of the limiting transients for Service Levels C and D is a key aspect of evaluating the integrity of reactor pressure vessels that contain materials with Charpy USE less than 50 ft- lb. In its RAI responses dated November 19, 2020, the PWROG explained that as documented in the UFSAR Section 5.2.4, the North Anna Leak-Before-Break (LBB) analysis was performed on the main coolant loop piping and was approved by the NRC on August 31 ,

1999; thus, the staff noted a main reactor coolant pipe break is not applicable . Further, the PWROG also confirmed that the Level D condition included the pipe rupture and Safe Shutdown Earthquake (SSE) loads on the nozzle and support pad for the EMA. Thus , the staff finds that the use of the Steam Line Break (SLB) transient in the TR adequately addressed K-1100 of Appendix K with respect to plant-specific Service Level C and D transients for North Anna .

3.2.5 Evaluation and Acceptance Criteria Per ASME Code, Section XL Appendix K 3.2.5.1 Service Level A and B Transients K-2200 states that when evaluating the weld material and the base material for Service Level A and B loadings, the postulated flaws (e .g., axial and/or circumferential) are interior semi-elliptical surface flaws with a depth of1/4 of the wall thickness and a length to depth (//a) aspect ratio of 6.

The J-integral resistance versus flaw extension curve shall be a conservative representation for the vessel material under evaluation. Furthermore , two criteria must be satisfied :

(1) The applied J-integral evaluated at a pressure 1.15 times the accumulation pressure as defined in the plant specific Overpressure Protection Report, with a structural factor of 1 on thermal loading for the plant specific heatup and cooldown conditions , shall be less than the J-integral of the material at a ductile flaw extension of 0.1 in . (2.5 mm).

(2) Flaw extensions at pressures up to 1 .25 times the accumulation pressure of K-2200(a)(1) shall be ductile and stable, using a structural factor of 1 on thermal loading for the plant specific heatup and cooldown conditions.

The staff noted that flaw stability at a given applied load is verified when the slope of the Japplied curve is less than the slope of the J-R curve at the point on the J-R curve where the two curves intersect , as described in K-4310 of Appendix K. The staff's review of the methodology, including inputs , for determining the Japplied are documented in SE Section 3.2.1 through 3.2.3.

RV Nozzle-to-Shell Welds The staff reviewed the results for the nozzle-to-shell welds and noted that the Japplied at 0.1-inch flaw extensions (J1) for the inlet nozzle-to-shell weld ([ ] lbf/in) and outlet nozzle-to-shell weld ([ ] lbf/in) are below the J-R at 0.1 inch flaw extension (Jo1) of [ ] lbf/in . Thus, the staff finds the acceptance criteria in K-2200(a)(1) of Appendix K is satisfied for the inlet nozzle-to-shell weld and outlet nozzle-to-shell weld. Furthermore, the staff reviewed the Figure 4-2 and Figure 4-3 of the TR and noted that the slope of Japp1;ec1 is less than the J-R curve at the intersection of curves for the inlet and outlet nozzle-to-shell welds, respectively ; thus, the staff NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xiv NON-PROPRIETARY INFORMATION finds that flaw stability has been verified and the acceptance criteria in K-2200(a)(2) of Appendix K is satisfied.

RV Upper Shell Forging The staff reviewed the results for the upper shell forging and noted that the Japplied at 0.1-inch flaw extensions (J1) for the circumferential flaw ([ ] lbf/in) and axial flaw ([ ] lbf/in) are below Jo.1 at the respective crack tip temperatures ([ ] lbf/in - circumferential flaw and

[ ] lbf/in - axial flaw). Thus, the staff finds the acceptance criteria in K-2200(a)(1) of Appendix K is satisfied for the upper shell forging. Furthermore, the staff reviewed the Figure 4-8 and Figure 4-9 of the TR, for the circumferential and axial flaw, respectively, and noted that the slope of Japplied is less than the J-R curve at the intersection of curves for the upper shell forging; thus, the staff finds that flaw stability has been verified and the acceptance criteria in K-2200(a)(2) of Appendix K is satisfied.

RV Nozzle Forging The staff reviewed the results for the inlet nozzle corner and noted that the Japplied at 0.1-inch flaw extensions (J1) for the circumferential flaw ([ ] lbf/in) and axial flaw ([ ] lbf/in) are below Jo 1 at the respective crack tip temperatures ([ ] lbf/in - circumferential flaw and

[ ] lbf/in - axial flaw) . Thus, the staff finds the acceptance criteria in K-2200(a)(1) of Appendix K is satisfied for the inlet nozzle corner. Furthermore , the staff reviewed the Figure 4-12 and Figure 4-14 of the TR, for the inlet nozzle forging circumferential and axial flaw, respectively, and noted that the slope of Japplied is less than the J-R curve at the intersection of curves; thus, the staff finds that flaw stability has been verified and the acceptance criteria in K-2200(a)(2) of Appendix K is satisfied.

The staff reviewed the results for the outlet nozzle corner and noted that the Japplied at 0.1-inch flaw extensions (J1) for the circumferential flaw ([ ] lbf/in) and axial flaw ([ ] lbf/in) are below Jo.1 at the respective crack tip temperatures ([ ] lbf/in - circumferential flaw and

[ ] lbf/in - axial flaw). Thus, the staff finds the acceptance criteria in K-2200(a)(1) of Appendix K is satisfied for the outlet nozzle corner. Furthermore , the staff reviewed the Figure 4-13 and Figure 4-15 of the TR, for the outlet nozzle forging circumferential and axial flaw, respectively, and noted that the slope of Japplied is less than the J-R curve at the intersection of curves; thus, the staff finds that flaw stability has been verified and the acceptance criteria in K-2200(a)(2) of Appendix K is satisfied.

3.2.5.2 Service Level C and D Transients As discussed in SE Section 3.2.4 Service Level C transients are not applicable to the CLB for North Anna; thus, K-2300 of Appendix K is not applicable .

In accordance with K-2400(a), the Level D postulated flaws shall be the same as those specified for Level C in K-2300. Specifically, the postulated flaws (e.g., axial and/or circumferential) are interior semi-elliptical surface flaws with depths up to 1/10 of the wall thickness of the base metal plus cladding, with total depth not exceeding 1 inch. For cases where 1/10 wall thickness plus cladding exceeded 1 inch, 1 inch is used for the postulated flaws for Level D, and the length to depth (I/a) aspect ratio is 6. K-2400(a) further states flaw extensions shall be ductile and stable, using a structural factor of 1 on loading . K-2400(b) and (c) states that (1) the J- integral resistance versus flaw extension curve shall be a best estimate representation NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xv NON-PROPRIETARY INFORMATION (i.e., mean curve) for the vessel material under evaluation, and (2) the total flaw depth after stable flaw extension shall be less than or equal to 75% of the vessel wall thickness, and the remaining ligament shall not be subject to tensile instability, respectively. The staff noted that flaw stability at a given applied load is verified when the slope of the Japp1;ec1 curve is less than the slope of the J-R curve at the point on the J-R curve where the two curves intersect, as described in K-4310 of Appendix K. The staffs review of the methodology, including inputs, for determining the Japplied are documented in SE Section 3.2.1 through 3.2.3.

Section 4.1 .4 of the TR states the procedures for the J-applied calculation for Levels CID described in K-5000 of Appendix Kare the same as those for Levels A/B described in K-4000, except that the effect of cladding/base metal differential thermal expansion needs to be considered for Levels C/D per K-5210(a) . In its RAI responses dated November 19, 2020, the PWROG confirmed that the FEA for Level CID explicitly modeled the effect of the cladding/base metal differential thermal expansion by incorporating the cladding with appropriate material properties such as thermal expansion coefficients per ASME Section II. Based on the PWROG's confirmation, the staff finds that the TR addresses K-521 0(a) of Appendix K by including the cladding material properties consistent with ASME Section II.

RV Nozzle-to-Shell Welds The staff reviewed the results for the nozzle-to-shell welds and noted that the all applied J1 at various flaw depths for the inlet nozzle-to-shell weld and outlet nozzle-to-shell weld are below Jo.1 ([ ] lbf/in). Thus , the staff finds the acceptance criteria in K-2400(a) of Appendix K is satisfied for the inlet nozzle-to-shell weld and outlet nozzle-to-shell weld. Furthermore , the staff reviewed the Figure 4-5 and Figure 4-7 of the TR and noted that the slope of Japplied is less than the J-R curve at the intersection of curves for the inlet and outlet nozzle-to-shell welds, respectively; thus, the staff finds that flaw stability has been verified and the acceptance criteria in K-3400 of Appendix K is satisfied . Further based on its review of these figures , the staff noted that the flaw depth after stable flaw extension (i.e ., point at which the applied J-integral intersects the mean J-R curve) is a small percentage of the inlet and outlet nozzle-to-shell weld thickness ; thus, the staff finds the acceptance criteria in K-2400(c) related to 75% of the vessel wall thickness is satisfied . The staff reviewed Table 4-5 of the TR and noted that the maximum internal pressure during a SLB transient (i.e. , 2.5 ksi) is significantly less than the tensile instability pressures calculated per K-5300 of Appendix K; thus, the staff finds the acceptance criteria in K-2400(c) related to tensile instability of the remaining ligament is satisfied .

RV Upper Shell Forging The staff reviewed the results for the upper shell forging and noted that the all applied J1 at various flaw depths for the circumferential and axial flaws are below Jo.1 ([ ] lbf/in) . Thus, the staff finds the acceptance criteria in K-2400(a) of Appendix K is satisfied for the upper shell forging . Furthermore, the staff reviewed the Figure 4-10 and Figure 4-11 of the TR, for the circumferential and axial flaw, respectively, and noted that the slope of Jappliedis less than the J-R curve at the intersection of curves for the upper shell forging; thus, the staff finds that flaw stability has been verified and the acceptance criteria in K-3400 of Appendix K is satisfied for the upper shell forging . Further based on its review of these figures, the staff noted that the flaw depth after stable flaw extension (i.e. , point at which the applied J-integral intersects the mean J-R curve) is a small percentage of the upper shell forging thickness ; thus, the staff finds the acceptance criteria in K-2400(c) related to 75% of the vessel wall thickness is satisfied . The staff reviewed Table 4-8 of the TR and noted that the max imum internal pressure during a SLB NON-PROPRIETARY INFORMATION PWROG-19047-NP-A September, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xvi NON-PROPRIETARY INFORMATION transient (i.e., 2.5 ksi) is less than the tensile instability pressures calculated per K-5300 of Appendix K; thus, the staff finds the acceptance criteria in K-2400(c) related to tensile instability of the remaining ligament is satisfied.

RV Nozzle Forging The staff reviewed the results for the inlet and outlet nozzle corner and noted that the all applied J1 at various flaw depths for the circumferential and axial flaws are below Jo.1 ([ ] lbf/in).

Thus, the staff finds the acceptance criteria in K-2400(a) of Appendix K is satisfied for the inlet and outlet nozzle forging. Furthermore, the staff reviewed the Figure 4-16 through Figure 4-19 of the TR, for the circumferential and axial flaws of the applicable forging, and noted that the slope of Japplied is less than the J-R curve at the intersection of curves for both the inlet and outlet nozzle corners; thus, the staff finds that flaw stability has been verified and the acceptance criteria in K-3400 of Appendix K is satisfied for the inlet nozzle forging and outlet nozzle forging .

Further based on its review of these figures, the staff noted that the flaw depth after stable flaw extension (i.e., point at which the applied J-integral intersects the mean J-R curve) is a small percentage of the inlet and outlet nozzle forging thickness; thus, the staff finds the acceptance criteria in K-2400(c) related to 75% of the vessel wall thickness is satisfied . The staff reviewed Table 4-11 of the TR and noted that the maximum internal pressure during a SLB transient (i.e ., 2.5 ksi) is less than the tensile instability pressures calculated per K-5300 of Appendix K; thus, the staff finds the acceptance criteria in K-2400(c) related to tensile instability of the remaining ligament is satisfied .

4.0 CONCLUSION

S The N RC staff concludes that the TR demonstrates that for the components in the scope of this report for North Anna, there is adequate margin of safety against ductile fracture for Service Level A and B loads, and Service Level D loads, through the subsequent period of extended operation (i .e., 60-80 years of plant operation) . The NRC staff also concludes that the TR may be referenced in the SLR for North Anna, as a basis for demonstrating that the USE TLAA for the components in the scope of this report has been projected to the end of the period of extended operation in accordance with 10 CFR 54 .21 (c)(1)(ii) .

4.1 Summary of Regulatory Compliance The NRC has concluded , based on the considerations discussed above , that: (1) there is reasonable assurance that the health and safety of the public will not be endangered, and (2) there is reasonable assurance that such activities will be conducted in compliance with the NRC's regulations.

5.0 CONDITIONS, LIMITATIONS, AND/OR ACTION ITEMS Based on the review of this TR, NRC staff concludes that there is no condition or limitation for the EMA at North Anna that needs to be imposed at this time .

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6.0 REFERENCES

1. Letter from Michael Powell, Pressurized Water Reactor Owners Group, to USN RC Document Control Desk, May 27, 2020, Submittal of PWROG-19047-P/NP Revision 0, "North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML20149K668)

2. Letter from Michael Powell , Pressurized Water Reactor Owners Group, to USN RC Document Control Desk, December 3, 2020 , Transmittal of the Response to Request for Additional Information , RAls 1-7 Associated with PWROG-19047-P/NP, Revision 0, "North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis" (ADAMS Accession No. ML20338A520), and Enclosure - Westinghouse Response to U.S. NRC Request for Additional Information (RAI) for PWROG-19047-P/NP, Rev. 0, November 19, 2020 (ADAMS Accession No . ML20338A522)

3. Topical Report PWROG-19047-NP Revision 0, "North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis," May 2020 (ADAMS Accession No. ML20149K671)

4. American Society of Mechanical Engineers,Section XI, Division 1, "Rules for lnservice Inspection of Nuclear Power Plant Components," of the ASME Boiler and Pressure Vessel Code, New York

5. Eason, E. D.; Wright, J . E.; Nelson, E. E, NUREG/CR-5729, "Multivariable Modeling of Pressure Vessel and Piping J-R Data," May 1991 .

(https ://ntrl. ntis .gov/ NTR Udash boa rd/search Results/title Detail/NU REGC R5729 .xhtml)

6. BAW-2192, Revision 0, Supplement 1P/NP-A, Revision 0- Low Upper-Shelf Toughness Fracture Mechanics Analysis of Reactor Vessels of B&W Owners Reactor Vessel Working Group for Levels A & B Service Loads, April 19, 2019 (ADAMS Accession Nos. ML19101A355/ML19101A344)

7. BAW-2192, Revision 0, Supplement 2P/NP-A, Revision 0- Low Upper-Shelf Toughness Fracture Mechanics Analysis of Reactor Vessels of B&W Owners Reactor Vessel Working Group for Levels A & B Service Loads, August 31, 2020 (ADAMS Accession Nos. ML20234A361/ML20234A363)

8. NU REG 0800 Section 5.3.2, "Pressure Temperature Limits, Upper Shelf Energy, and Pressurized Thermal Shock" (ADAMS Accession No . ML070380185)

9. Regulatory Guide1 .161 , "Evaluation of Reactor Pressure Vessels with Charpy Upper-Shelf Energy Less Than 50 Ft-Lb," June 1995 (ADAMS Accession No. ML003740038)

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10. RG 1.190, "Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence," March 2001 (ADAMS Accession No. ML010890301)

11. RG 1.99, Revision 2, "Radiation Embrittlement of Reactor Vessel Materials," May 1988 (ADAMS Accession No. ML003740284)

12. PWROG-17090-NP-A Revision O - Generic Rotterdam Forging and Weld Initial Upper-Shelf Energy Determination (PA-MSC-1367, Task 3), January 2020 (ADAMS Accession No. ML20024E238)

13. WCAP-18364-NP, Rev. 1 - North Anna Units 1 and 2 Time-Limited Aging Analysis on Reactor Vessel Integrity for Subsequent License Renewal (SLR), March 31, 2020 (ADAMS Accession No. ML20246G701)

14. WCAP-18015-NP, Revision "Extended Beltline Pressure Vessel Fluence Evaluations Applicable to North Anna 1 & 2, " September 2018 (ADAMS Accession No. ML20140A336)

15. North Anna Power Station, Unit Nos. 1 and 2 - RE: Request To Revise Reactor Vessel Material Surveillance Capsule Withdrawal Schedules (EPID L-2019-LLL-0038), August 6, 2020 (ADAMS Accession No. ML20216A299)

16. WCAP 14040-A, Revision 4, "Methodology Used to Develop Cold Overpressure Mitigating System Setpoints and RCS Heatup and Cooldown Limit Curves," May 31, 2004 (ADAMS Accession No. ML050120209)

17. North Anna Power Station, Units 1 & 2, Revision 56 to Updated Final Safety Analysis Report (ADAMS Accession No. ML20309A590)

Principal Contributors: On Yee, NRR/DNRL David Dijamco, NRR/DNRL Benjamin Parks, NRR/DSS Date:

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xix NON-PROPRIETARY INFORMATION TOPICAL REPORT PWROG-19047-P/NP, REVISION 0 COMMENT DISPOSITION TABLE Comment No . Comment Comment Suggested Revision NRC Response Text Location Type in the DSE (Clarification, Page Line Editorial, PWROG NRC No. No . Accuracy, Proprietary) 1 6 25 Editorial Please add : "Rev. 0, " NRC staff finds the after BAW-2192. PWROG comment acceptable and the revisions have been incorporated .

2 6 27 Editorial Please add : "Rev. 0, " NRC staff finds the after BAW-2192; and PWROG comment acceptable and Please add : "-A" after the revisions have Supplement 2P.

been incorporated.

3 6 29 Editorial Please add : "Rev. 0, " NRC staff finds the after BAW-2192; and PWROG comment acceptable and Please add : "-A" after the revisions have Supplement 2P.

been incorporated .

4 9 39-40 Proprietary Add [ ) and yellow NRC has provided highlight to identify add'I comments.

proprietary values of J1 Revisions have and Jo.1. been incorporated .

5 10 2-4 Proprietary Add I I and yellow NRC has provided highlight to identify add'I comments.

proprietary values of J1 Revisions have and Jo 1. been incorporated .

6 10 14-16 Proprietary Add [ ) and yellow NRC has provided highlight to identify add'I comments.

proprietary values of J1 Revisions have and Jo.1. been incorporated.

7 10 24-26 Proprietary Add [ ) and yellow NRC has provided highlight to identify add'I comments.

proprietary values of J1 Revisions have and Jo.1. been incorporated.

8 11 18 Proprietary Add [ ] and yellow NRC provided highlight to identify add'I comments.

proprietary value of J . 1 Revisions have been incorporated.

9 11 35 Proprietary Add [ ] and yellow NRC has provided highlight to identify add'I comments.

proprietary value of Jo.1 Revisions have been incorporated.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xx NON-PROPRIETARY INFORMATION TOPICAL REPORT PWROG-19047-P/NP, REVISION 0 COMMENT DISPOSITION TABLE Comment No . Comment Comment Suggested Revision NRC Response Text Location Type in the DSE (Clarification, Page Line Editorial, PWROG NRC No. No. Accuracy, Proprietary) 10 12 3 Proprietary Add [ ) and yellow NRC has provided highlight to identify add'I comments.

proprietary value of Jo.1. Revisions have been incorporated.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xxi ACKNOWLEDGEMENTS This topical report was developed and funded by the PWR Owners Group under the leadership of the participating utility representatives of the Materials Committee. The author would like to thank the following people and/or organizations for their valuable contributions to this report:

Mark Rinckel, Framatome Martin Kolar, Framatome Chuck Tomes, Dominion PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xxii LEGAL NOTICE This report was prepared as an account of work performed by Westinghouse Electric Company LLC and Framatome Inc. Neither Westinghouse Electric Company LLC nor Framatome Inc. nor its affiliates, nor any person acting on its behalf:

Makes any warranty or representation, express or implied including the warranties of fitness for a particular purpose or merchantability, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or Assumes any liabilities with respect to the use of, or for damages resulting from the use of, any information, apparatus, method, or process disclosed in this report.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xxiii DISTRIBUTION NOTICE This report was prepared for the PWR Owners Group. This Distribution Notice is intended to establish guidance for access to this information. This report (including proprietary and non-proprietary versions) is not to be provided to any individual or organization outside of the PWR Owners Group program participants without prior written approval of the PWR Owners Group Program Management Office. However, prior written approval is not required for program participants to provide copies of Class 3 Non-Proprietary reports to third parties that are supporting implementation at their plant, and for submittals to the NRC.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xxiv PWR Owners Group United States Member Participation* for PA- MSC-1481, R3 Participant Utility Member Plant Site(s) Yes No Ameren Missouri Callaway (W) X American Electric Power D.C. Cook 1 & 2 (W) X Arizona Public Service Palo Verde Unit 1, 2, & 3 (CE) X Millstone 2 (CE) X Millstone 3 (W) X Dominion Energy North Anna 1 & 2 (W) X Surry 1 & 2 (W) X V.C. Summer (W) X Catawba 1 & 2 (W) X Duke Energy Carolinas McGuire 1 & 2 (W) X Oconee 1, 2, & 3 (B&W) X Robinson 2 (W) X Duke Energy Progress Shearon Harris (W) X Entergy Palisades Palisades (CE) X Entergy Nuclear Northeast Indian Point 2 & 3 (W) X Arkansas 1 (B&W) X Entergy Operations South Arkansas 2 (CE) X Waterford 3 (CE) X Braidwood 1 & 2 (W) X Byron 1 & 2 (W) X Exelon Generation Co. LLC Calvert Cliffs 1 & 2 (CE) X Ginna (W) X Beaver Valley 1 & 2 (W) X FirstEnergy Nuclear Operating Co.

Davis-Besse (B&W) X St. Lucie 1 & 2 (CE) X Turkey Point 3 & 4 (W) X Florida Power & Light \ NextEra Seabrook (W) X Pt. Beach 1 & 2 (W) X Luminant Power Comanche Peak 1 & 2 (W) X PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xxv PWR Owners Group United States Member Participation* for PA- MSC-1481, R3 Participant Utility Member Plant Site(s) Yes No Pacific Gas & Electric Diablo Canyon 1 & 2 (W) X PSEG - Nuclear Salem 1 & 2 (W) X So. Texas Project Nuclear Operating Co. South Texas Project 1 & 2 (W) X Farley 1 & 2 (W) X Southern Nuclear Operating Co.

Vogtle 1 & 2 (W) X Sequoyah 1 & 2 (W) X Tennessee Valley Authority Watts Bar 1 & 2 (W) X Wolf Creek Nuclear Operating Co. Wolf Creek (W) X Xcel Energy Prairie Island 1 & 2 (W) X

• Project participants as of the date the final deliverable was completed. On occasion, additional members will join a project. Please contact the PWR Owners Group Program Management Office to verify participation before sending this document to participants not listed above.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xxvi PWR Owners Group International Member Participation* for PA- MSC-1481, R3 Participant Utility Member Plant Site(s) Yes No Asco 1 & 2 (W) X Asociación Nuclear Ascó-Vandells Vandellos 2 (W) X Centrales Nucleares Almaraz-Trillo Almaraz 1 & 2 (W) X EDF Energy Sizewell B (W) X Doel 1, 2 & 4 (W) X Electrabel Tihange 1 & 3 (W) X Electricite de France 58 Units X Elektriciteits Produktiemaatschappij Zuid- Borssele 1 (Siemens) X Nederland Eletronuclear-Eletrobras Angra 1 (W) X Emirates Nuclear Energy Corporation Barakah 1 & 2 X Hokkaido Tomari 1, 2 & 3 (MHI) X Japan Atomic Power Company Tsuruga 2 (MHI) X Mihama 3 (W) X Kansai Electric Co., LTD Ohi 1, 2, 3 & 4 (W & MHI) X Takahama 1, 2, 3 & 4 (W & MHI) X Kori 1, 2, 3 & 4 (W) X Hanbit 1 & 2 (W) X Korea Hydro & Nuclear Power Corp.

Hanbit 3, 4, 5 & 6 (CE) X Hanul 3, 4 , 5 & 6 (CE) X Genkai 2, 3 & 4 (MHI) X Kyushu Sendai 1 & 2 (MHI) X Nuklearna Electrarna KRSKO Krsko (W) X Ringhals AB Ringhals 2, 3 & 4 (W) X Shikoku Ikata 2 & 3 (MHI) X Taiwan Power Co. Maanshan 1 & 2 (W) X

• Project participants as of the date the final deliverable was completed. On occasion, additional members will join a project. Please contact the PWR Owners Group Program Management Office to verify participation before sending this document to participants not listed above.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xxvii TABLE OF CONTENTS 1 INTRODUCTION ............................................................................................................ 1-1

2 REGULATORY REQUIREMENTS ................................................................................. 2-1

2.1 REGULATORY REQUIREMENTS ..................................................................... 2-1

2.2 COMPLIANCE WITH 10 CFR 50 APPENDIX G AND ACCEPTANCE CRITERIA ........................................................................................................... 2-2

2.2.1 Acceptance Criteria ............................................................................. 2-2

3 EQUIVALENT MARGINS ANALYSIS INPUTS ............................................................... 3-1

3.1 FINITE ELEMENT STRESS ANALYSIS ............................................................. 3-1

3.2 J-INTEGRAL RESISTANCE MODELS ............................................................... 3-4

4 FRACTURE MECHANICS ANALYSIS ........................................................................... 4-1

4.1 METHODOLOGY DISCUSSION ........................................................................ 4-1

4.1.1 Nozzle-to-Shell Welds and Upper Shell Forging, KI Using A-3200

[8] ......................................................................................................... 4-1 4.1.2 Nozzle Corner KI Closed Form Solution per [11] ................................. 4-3

4.1.3 Calculation of Japplied for Small-Scale Yielding ...................................... 4-4

4.1.4 Postulated Flaw ................................................................................... 4-4

4.1.5 Weld Residual Stress .......................................................................... 4-4

4.1.6 Stress Due to Mechanical Loads ......................................................... 4-5

4.1.7 Temperature Range for Upper Shelf Fracture Toughness Evaluations .......................................................................................... 4-5

4.2 APPLIED J-INTEGRAL RESULTS AND COMPARISON WITH J-R CURVES ALLOWABLES .................................................................................... 4-6

4.2.1 Nozzle-to-Shell Welds Level A/B ......................................................... 4-6

4.2.2 Nozzle-to-Shell Welds Level D ............................................................ 4-8

4.2.3 Upper Shell Forging Level A/B........................................................... 4-15

4.2.4 Upper Shell Forging Level D.............................................................. 4-17

4.2.5 Nozzle Forging Level A/B .................................................................. 4-20

4.2.6 Nozzle Forging Level D ..................................................................... 4-24

5 CONCLUSIONS ............................................................................................................. 5-1

6 REFERENCES ............................................................................................................... 6-1

APPENDIX A : CORRESPONDENCE WITH U.S. NRC REGARDING THE REVIEW OF PWROG-19047-P, REVISION 0 .....................................................................................$1

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xxviii LIST OF TABLES Table 3-1: Base Metal Material Properties (SA-508 Class 2) ..................................................... 3-3

Table 3-2: Cladding Material Properties (Type 304 Stainless Steel) .......................................... 3-3

Table 3-3: J-R Calculation Input Parameters for Nozzle Welds ................................................. 3-4

Table 3-4: Model 6B J-R curve for Nozzle-to Shell Welds at 552°F for Levels A/B................... 3-4

Table 3-5: Parameters for RPV Base Metals, Jd Model [3, Table 11] ......................................... 3-6

Table 3-6: RV Inlet and Outlet Nozzle Forgings J-R Curves ..................................................... 3-6

Table 3-7: RV Intermediate Shell Forgings J-R Curves ............................................................ 3-7

Table 4-1: Inlet and Outlet Nozzle Welds Levels A/B, Circumferential Flaw, Japplied ................... 4-6

Table 4-2: Inlet and Outlet Nozzle Welds Level D, Circumferential Flaw, Limiting Japplied........... 4-9

Table 4-3: B&WOG Model 6-B Mean J-R Curve with a = 0.1 inch ........................................ 4-10

Table 4-4: KIc2/E Curve ............................................................................................................ 4-10

Table 4-5: K-5300 Tensile Instability Check for RV Nozzle-to-Shell Weld ................................ 4-15

Table 4-6: Upper Shell Forging Level A/B, Circumferential Flaw, Limiting Japplied ..................... 4-15

Table 4-7: Upper Shell Forging Level D, Limiting Japplied .......................................................... 4-18

Table 4-8: K-5300 Tensile Instability Check for RV Upper Shell .............................................. 4-19

Table 4-9: Nozzle Corner Level A/B, Limiting Japplied ................................................................ 4-20

Table 4-10: Nozzle Corner Level D, Limiting Japplied ................................................................. 4-25

Table 4-11: K-5300 Tensile Instability Check for RV Nozzle Corner ........................................ 4-29

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY xxix LIST OF FIGURES Figure 3-1: North Anna Units 1 and 2 Reactor Vessel Generic Configuration ........................... 3-1

Figure 3-2: Overview of FEM ..................................................................................................... 3-2

Figure 4-1: KI Solution for Quarter Circular Crack in Quarter Space [11, page 5]...................... 4-3

Figure 4-2: Inlet Nozzle Weld, Circumferential Flaw, Levels A/B Japplied vs. J-R, SF=1.25 ......... 4-7

Figure 4-3: Outlet Nozzle Weld, Circumferential Flaw, Levels A/B Japplied vs. J-R, SF=1.25 ...... 4-8

Figure 4-4: Inlet Nozzle-to-Shell Weld, J-integral vs. Temperature .......................................... 4-11

Figure 4-5: Inlet Nozzle-to-Shell Weld, J-integral vs. Flaw Extension...................................... 4-12

Figure 4-6: Outlet Nozzle-to-Shell Weld, J-integral vs. Temperature ....................................... 4-13

Figure 4-7: Outlet Nozzle-to-Shell Weld, J-integral vs. Flaw Extension ................................... 4-14

Figure 4-8: RV Upper Shell, Circumferential Flaw, Level A/B Japplied vs. J-R, SF=1.25 ............ 4-16

Figure 4-9: RV Upper Shell, Axial Flaw, Level A/B Japplied vs. J-R, SF=1.25 ............................. 4-17

Figure 4-10: RV Upper Shell, Circumferential Flaw, Level D Japplied vs. J-R ............................. 4-18

Figure 4-11: RV Upper Shell, Axial Flaw, Level D Japplied vs. J-R .............................................. 4-19

Figure 4-12: Inlet Nozzle Corner, Circumferential Flaw, Level A/B Japplied vs. J-R, SF=1.25 .... 4-21

Figure 4-13: Outlet Nozzle Corner, Circumferential Flaw, Level A/B Japplied vs. J-R, SF=1.25 . 4-22

Figure 4-14: Inlet Nozzle Corner, Axial Flaw, Level A/B Japplied vs. J-R, SF=1.25 ..................... 4-23

Figure 4-15: Outlet Nozzle Corner, Axial Flaw, Level A/B Japplied vs. J-R, SF=1.25 .................. 4-24

Figure 4-16: Inlet Nozzle Corner, Circumferential Flaw, Level D Japplied vs. J-R, SF=1.0 ......... 4-26

Figure 4-17: Outlet Nozzle Corner, Circumferential Flaw, Level D Japplied vs. J-R, SF=1.0 ...... 4-27

Figure 4-18: Inlet Nozzle Corner, Axial Flaw, Level D Japplied vs. J-R, SF=1.0 .......................... 4-28

Figure 4-19: Outlet Nozzle Corner, Axial Flaw, Level D Japplied vs. J-R, SF=1.0 ....................... 4-29

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 1-1 1 INTRODUCTION The purpose of this topical report is to document the equivalent margins analysis (EMA) for the North Anna Units 1 and 2 reactor vessel (RV) inlet and outlet nozzle Rotterdam welds, nozzle forgings and nozzle belt forgings (a.k.a., upper shell forgings). These locations were chosen for their upper-shelf energy (USE) potentially falling below the 50 ft-lb limit at 80-years (72 EFPY) for subsequent license renewal (SLR). Materials with end-of-license-extension (EOLE) USE below the 50 ft-lb limit are required to be evaluated per paragraph IV.A.1.a of 10 CFR 50, Appendix G, for equivalent margins of safety specified in ASME Code Section XI, Appendix K [8].

The North Anna Units 1 and 2 reactor vessels are Westinghouse-designed vessels whose subject nozzle welds were fabricated by the Rotterdam Shipyards. There are only two locations with projected SLR USE at or below the required 50 ft-lbs:

x North Anna Unit 1, Inlet Nozzle Forging 11, Heat #990268-21 x North Anna Unit 2, Intermediate Shell Forging 04, Heat #990496 / 292424 The EMA for the nozzle and upper shell forgings utilizes the multivariable model for RV base metal reported in NUREG/CR-5729. Although the Rotterdam nozzle-to-shell welds are projected to have USE greater than 50 ft-lbs, they are evaluated proactively in this EMA for asset management consideration. The EMA for the Rotterdam welds utilizes the B&WOG J-integral resistance (J-R) Model 6B reported in BAW-2192, Revision 0, Supplement 1P-A, Rev. 0, Appendix A [1]. The justification for using the B&WOG Model 6B for the North Anna Rotterdam welds is addressed in BAW-2192, Supplement 2P, Revision 0 [2].

This low upper-shelf toughness EMA is based on the projected RV neutron fluence at 80 years of operation for SLR at the RV inlet and outlet nozzle regions, which are projected to exceed 1.0 E+17 n/cm2, E > 1.0 MeV, and are qualified as extended beltline materials. The general configuration of the North Anna Units 1 and 2 RVs, and the locations evaluated in this EMA are shown in Figure 3-1. There are no longitudinal welds on the North Anna Units 1 and 2 RVs.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 2-1 2 REGULATORY REQUIREMENTS 2.1 REGULATORY REQUIREMENTS In accordance with 10 CFR 50, Appendix G, IV.A.1, [4] Reactor Vessel Upper Shelf Energy Requirements are as follows.

(a) Reactor Vessel beltline materials must have Charpy upper-shelf energy in the transverse direction for base material and along the weld for weld material according to the ASME Code, of no less than 75 ft-lb (102 J) initially and must maintain Charpy upper-shelf energy throughout the life of the vessel of no less than 50 ft-lb (68 J), unless it is demonstrated in a manner approved by the Director, Office of Nuclear Reactor Regulation or Director, that lower values of Charpy upper-shelf energy will provide margins of safety against fracture equivalent to those required by Appendix G of Section XI of the ASME Code. This analysis must use the latest edition and addenda of the ASME Code incorporated by reference into 10 CFR 50.55a (b)(2) at the time the analysis is submitted.

(b) Additional evidence of the fracture toughness of the beltline materials after exposure to neutron irradiation may be obtained from results of supplemental fracture toughness tests for use in the analysis specified in section IV.A.1.a.

(c) The analysis for satisfying the requirements of section IV.A.1 of this appendix must be submitted, as specified in § 50.4, for review and approval on an individual case basis at least three years prior to the date when the predicted Charpy upper-shelf energy will no longer satisfy the requirements of section IV.A.1 of this appendix, or on a schedule approved by the Director, Office of Nuclear Reactor Regulation.

When the RVs within the scope of this topical report were fabricated, the Charpy V-notch testing of the RV welds was in accordance with the original construction code, which did not require Charpy V-notch tests on the upper shelf. The original construction code for the RV shell and nozzles for both units is ASME Section III, 1968 Edition through the Winter 1968 Addenda, as discussed in the North Anna Units 1 and 2 Updated Final Safety Analysis Report (UFSAR) [5, Table 5.2-3].

In accordance with NRC Regulatory Guide 1.161 [6], the NRC has determined that the analytical methods described in ASME Section XI, Appendix K, provide acceptable guidance for evaluating reactor pressure vessels when the Charpy USE falls below the 50 ft-lb limit of Appendix G of 10 CFR Part 50. However, the staff noted that Appendix K does not provide information on the selection of transients and provides very little detail on the selection of material properties.

Consistent with BAW-2192, Revision 0, Supplement 1P-A, Revision 0 [1], the cooldown transient for North Anna Units 1 and 2 with a constant pressure of 2750 psia assumed throughout the transient bounds all Levels A/B conditions. This is consistent with and based on the ASME Section XI, Appendix K 100°F/hour cooldown rate guidance coincident with the use of a high pressure value. The Level C/D transient selection is based on the guidance in Regulatory Guide PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 2-2 1.161 Section 4.0 [6]. There are no applicable emergency (Level C) transients in the RV design specifications. The Level D transient is the steam line break (SLB). Additional transient discussions are contained in Section 4.1. Physical properties for the forging and weld materials are from construction ASME Code [7]. The J-Resistance (J-R) models are discussed in detail in Section 3.2.

2.2 COMPLIANCE WITH 10 CFR 50 APPENDIX G AND ACCEPTANCE CRITERIA The analyses reported herein are performed in accordance with the 2013 Edition of Section XI of the ASME Code, Appendix K [8]. The edition of ASME Section XI discussed in 10 CFR 50.55a is the 2013 Edition. The material properties used in this analysis are based on the original RV construction code, ASME Boiler and Pressure Vessel Code,Section III, 1968 Edition, with Addenda up to and including the Winter of 1968 [7].

2.2.1 Acceptance Criteria ASME Section XI [8], Appendix K provides the acceptance criteria for the Level A, B, C and D conditions. These criteria summarized in the following subsections are consistent with Regulatory Guide 1.161.

2.2.1.1 K-2200 Levels A and B Service Loadings (a) Postulated axial and circumferential flaws are interior semi-elliptical surface flaws with a depth of 1/4 of the wall thickness and a length to depth (l/a) aspect ratio of 6.

(1) Japplied with a SF of 1.15 for pressure and a SF of 1.0 for thermal (cooldown) shall be less than the J-integral of the material (J-R curve) at a ductile flaw extension of 0.1 inch.

(2) Japplied with a SF of 1.25 for pressure and a SF of 1.0 for thermal (cooldown) shall be ductile and stable.

(b) The J-R curve shall be a conservative representation for the vessel material under evaluation.

The flaw stability criteria is per K-3400: at J

• JR. This is further explained in K-4310.

The J-R curve shall be plotted on the crack driving force diagram and shall intersect the horizontal axis at the initial flaw depth, a0. Flaw stability at a given applied load is verified when the slope of the Japplied curve is less than the slope of the J-R curve at the point on the J-R curve where the two curves intersect.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 2-3 2.2.1.2 K-2300 and K-2400, Levels C and D Service Loadings Per K-2400, the Level D postulated flaws shall be the same as those specified for Level C in K-2300.

(a) Postulated axial and circumferential flaws are interior semi-elliptical surface flaws with depths up to 1/10 of the wall thickness of the base metal plus cladding, with total depth not exceeding 1 inch. For cases where 1/10 wall thickness plus cladding exceeded 1 inch, 1 inch is used for the postulated flaws for Level D. The length to depth (l/a) aspect ratio is 6.

(1) Japplied with a SF of 1.0 for thermal and pressure shall be less than the J-R curve at a ductile flaw extension of 0.1 inch.

(2) Japplied with a SF of 1.0 for thermal and pressure shall be ductile and stable.

(b) The J-R curve shall be a conservative representation for the vessel material under evaluation.

(c) The total flaw depth after stable flaw extension shall be less than or equal to 75% of the vessel wall thickness, and the remaining ligament shall not be subject to tensile instability.

The flaw stability criteria is detailed in K-5300.

(a) Stability is verified per K-3400: at J

• JR.

(b) For Level D Service Loadings, demonstrate that total flaw depth after stable flaw extension is less than or equal to 75% of the vessel wall thickness, and the remaining ligament is not subjected to tensile instability. The internal pressure shall be less than the instability pressure (PI), calculated by the equations below:

/

(1) For axial flaw, 1.07

/

(2) For circumferential flaw, 1.07 PI is limited to 1.07 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 2-4 where, o = Flow stress, average of yield strength and ultimate tensile strength A = An area parameter = t (l + t)

Ac = Area of the flaw = al / 4 Ri = Inner radius of the vessel Rm = Mean radius of the vessel t = Wall thickness of the vessel a = Flaw Depth l = Flaw length PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 3-1 3 EQUIVALENT MARGINS ANALYSIS INPUTS 3.1 FINITE ELEMENT STRESS ANALYSIS The general procedures for J-integral calculation are described in Appendix K of [8]. As discussed in Section 2.1, the cooldown transient was analyzed to bound Levels A/B. The Level D transient is SLB. Figure 3-1 is a sketch illustrating the North Anna RV upper shell, intermediate shell, inlet and outlet nozzles, and nozzle to shell welds. The finite element model (FEM) is illustrated in Figure 3-2. Geometry and dimensions are taken from design drawings. The applied loadings consist of pressure, thermal and attached piping and support reactions at RV nozzles.

Table 3-1 lists the material properties of SA-508 Class 2 used for the RV shell and nozzle forging base metal. The nozzle-to-shell weld mechanical properties were assumed to be identical to the forging material for the purpose of stress analysis. Table 3-2 lists the material properties for Type 304 stainless steel were used for the cladding.

UPPEA SHELL truRSE

• 1 Inlet/Outlet Nozzle Nozzle Forging to Shell Welds* Corner Location*

OUlLET NOZZLE I IMK 2. 13 ANO t i VESSEt PAO Intermediate Shell Forging*

• EMA Evaluated Locations for North Anna Units 1 and 2 Figure 3-1: North Anna Units 1 and 2 Reactor Vessel Generic Configuration PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 3-2

--c====---===~

0.000 0.500 1.000 1.500 2.000 (m)

Figure 3-2: Overview of FEM PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 3-3 Table 3-1: Base Metal Material Properties (SA-508 Class 2)

Thermal Thermal Heat Capacity, Temp E Temp Conductivity, K Density, Expansion, Diffusivity, Cp

[°F] [x106 psi] [°F] -6 [BTU/(hrft°F)] 2 [lbm/in3]

[x10 in/(in°F)] [ft /hr] [BTU/(lbm°F)]

70 27.9 70 6.07 31.50 0.5692 0.1144 0.28 200 27.7 100 6.13 31.00 0.5509 0.1163 0.28 300 27.4 150 6.25 30.50 0.5421 0.1163 0.28 400 27.0 200 6.38 30.00 0.5246 0.1182 0.28 500 26.4 250 6.49 29.50 0.5075 0.1201 0.28 600 25.7 300 6.60 29.10 0.4928 0.1220 0.28 700 24.8 350 6.71 28.60 0.4770 0.1239 0.28 400 6.82 28.10 0.4616 0.1258 0.28 450 6.92 27.60 0.4467 0.1277 0.28 500 7.02 27.20 0.4338 0.1296 0.28 550 7.12 26.70 0.4198 0.1315 0.28 600 7.23 26.20 0.4061 0.1333 0.28 650 7.33 25.80 0.3915 0.1362 0.28 700 7.41 25.30 0.3763 0.1390 0.28 Table 3-2: Cladding Material Properties (Type 304 Stainless Steel)

Thermal Thermal Heat Capacity, Temp E Temp Conductivity, K Density, Expansion, Diffusivity, Cp

[°F] [x106 psi] [°F] -6 [BTU/(hrft°F)] 2 [lbm/in3]

[x10 in/(in°F)] [ft /hr] [BTU/(lbm°F)]

70 27.4 70 9.11 8.35 0.1498 0.1112 0.29 200 27.1 100 9.16 8.40 0.1495 0.1121 0.29 300 26.8 150 9.25 8.67 0.1525 0.1135 0.29 400 26.4 200 9.34 8.90 0.1548 0.1147 0.29 500 26.0 250 9.41 9.12 0.1568 0.1160 0.29 600 25.4 300 9.47 9.35 0.1589 0.1174 0.29 700 24.9 350 9.53 9.56 0.1601 0.1192 0.29 400 9.59 9.80 0.1630 0.1200 0.29 450 9.65 10.00 0.1639 0.1218 0.29 500 9.70 10.23 0.1659 0.1231 0.29 550 9.76 10.45 0.1684 0.1238 0.29 600 9.82 10.70 0.1707 0.1251 0.29 650 9.87 10.90 0.1721 0.1264 0.29 700 9.93 11.10 0.1736 0.1276 0.29 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 3-4 3.2 J-INTEGRAL RESISTANCE MODELS North Anna Units 1 and 2 RV are Westinghouse-design vessels whose subject nozzle-to-shell welds were fabricated by Rotterdam Shipyards. The nozzle weld EMA utilizes the B&WOG J-R model 6B reported in BAW-2192, Revision 0, Supplement 1P-A, Revision 0, Appendix A [1]. The justification for the use of Model 6B for North Anna the nozzle-to-shell welds is provided in BAW-2192, Supplement 2P, Revision 0 [2]. For conservatism, the maximum cold leg temperature is utilized. Similarly, the maximum reported copper content and the fluence value at the nozzle-to-shell weld is utilized as summarized in Table 3-3 below. Table 3-4 lists the J-R curve for the nozzle-to-shell welds provided by Framatome.

Table 3-3: J-R Calculation Input Parameters for Nozzle Welds f

Table 3-4: Model 6B J-R curve for Nozzle-to Shell Welds at 552°F for Levels A/B f

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 3-5 The J-R curves for the RV nozzle and shell forgings were developed in accordance with NUREG/CR-5729 [3], Table 11, Charpy model without fluence. This Charpy model is the same model described in Section 3.3 of Regulatory Guide 1.161 [6]. The test specimens net-section thickness, Bn of 1.0 inches is used per Section 3 of [6]. The Charpy model is applicable to North Anna nozzle and shell forgings because they are bounded by the range of explanatory variables (fluence, copper content, etc.) used to develop the J-R model. The calculated J-R curve data for the nozzle and shell forging is listed in Table 3-6 and Table 3-7.

The basic form JR is expressed in [3 and 6] as:

JR = (MF)C1(a)C2exp[C3(a)C4] Equation 1

where, MF = margin factors, = 0.749 for Levels A, B and C; MF = 1.0 for Level D a = flaw extension, inches For the Charpy model, C1 is defined in [3, Eq. 10] as:

lnC1 = a1 + a2lnCVN + a3T + a4lnBn Equation 2

where, a1 through a5 are defined in [3, Table 11], and shown in Table 3-5.

CVN = Charpy V-notch Impact Energy, ft-lbs. The 80-year projected USE value is used.

T = temperature, °F Bn = test specimen net thickness, inches. Bn = 1.0 inch is used per Section 3 of [6].

C2 and C3 are defined in [3, Eq. 7 and 8] as:

C2 = d1 + d2lnC1 + d3lnBn Equation 3 C3 = d4 + d5lnC1 + d6lnBn Equation 4

where, d1 through d6 are defined in [3, Table 11], and shown in Table 3-5.

C4 is defined in [3, Table 11], and shown in Table 3-5.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 3-6 Table 3-5: Parameters for RPV Base Metals, Jd Model [3, Table 11]

Parameter Variable Charpy Model a1 (constant) -2.44 a2 ln CVN 1.13 lnC1 a3 T -0.00277 C2 a4 a5 d1 d2 lnBn t

(constant) lnC1 0.0801 0.077 0.116 d3 lnBn -0.0412 d4 (constant) -0.0812 C3 d5 lnC1 -0.0092 d6 lnBn -0.0295 C4 C4 (exponent) -0.409 Table 3-6: RV Inlet and Outlet Nozzle Forgings J-R Curves a, c, e Note: NUREG/CR-5729 Charpy Model was used.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 3-7 Table 3-7: RV Intermediate Shell Forgings J-R Curves a, c, e Note:

NUREG/CR-5729 Charpy Model was used. The limiting location for the upper shell is near the intermediate shell.

Since the J-R curves for the intermediate shell are more limiting than the upper shell, they are used in the EMA for the upper shell. Additionally, since the upper shell forging stresses were taken from the upper shell to intermediate shell transition, the stress concentration effect was captured, therefore, the upper shell Japplied results are also applicable to the intermediate shell.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-1 4 FRACTURE MECHANICS ANALYSIS The EMA methodology that was used for the North Anna Units 1 and 2 RV locations with projected USE below 50 ft-lbs is consistent with previously NRC approved methodologies for WCAP-13587, Rev. 1, BAW-2178 and BAW-2192. The respective NRC Safety Evaluation Reports are in [12 and 13]. The EMA methodology is discussed further in Section 4.1. Although the Rotterdam nozzle-to-shell welds are projected to have a USE greater than 50 ft-lbs, they are evaluated in this EMA proactively for asset management consideration.

4.1 METHODOLOGY DISCUSSION The Japplied are to be calculated per ASME Section XI, Appendix K [8], which is consistent with BAW-2192, Revision 0, Supplement 1P-A [1]. The maximum Japplied values at the critical time points for service Levels A/B and Levels C/D, along with plots of Japplied vs. flaw depth, will be compared with the J-R curves for the EMA. The Levels A/B service loadings required by ASME Section XI, Appendix K, are an accumulation pressure (internal pressure load) and a cooldown rate (thermal load). For Level A/B, K-1300 and K-4000 of [8] conservatively defined the accumulation pressure as 1.1 times the design pressure, which is a constant pressure of 2750 psia applied throughout the 100°F/hr cooldown transient.

The actual design thermal transients are used for finite element analysis (FEA) stress and input for the K and J calculations, instead of the generic design pressure and cooling rate in Appendix K [8]. As discussed in Section 2.1 of this topical report, the plant cooldown transient is used to bound all Level A/B conditions. This is also consistent with the Appendix K guidance of 100°F/hour cooldown rate. Based on the design specification, there is no Level C transient for North Anna Units 1 and 2, and only the SLB transient is specified for Level D conditions. The Level D thermal and pressure transients are defined in the design specification. Instead of lumping Levels C and D together as traditional EMA would do, this topical report will refer to it as Level D instead of Level C/D for clarity because there is no Level C conditions.

Appendix K of [8] provides various postulated flaw depths, locations, and orientations, as well as the Japplied and stability criteria. Per K-2000 of [8], the postulated flaws shall be oriented along the major axis of the weld of concern. Therefore, only circumferential flaws are applicable to the inlet and outlet nozzle welds. Both axial and circumferential flaws will be postulated for the nozzle and upper shell forgings.

4.1.1 Nozzle-to-Shell Welds and Upper Shell Forging, KI Using A-3200 [8]

For an axial or circumferential flaw of depth a, the SIF due to radial thermal gradients can be calculated per K-4210(c) of [8]. However, since the thermal stresses are based on FEA, the procedure in ASME Section XI, Appendix A [8] is used to calculate the SIFs. This method accurately captures the stress states of the actual geometry. The stress profile representation prescribed in A-3200 of [8] is for a location over the flaw depth (x/a) for which the Ai coefficients need to be recalculated for every flaw depth analyzed. The term x is defined as the distance PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-2 through the wall measured from the flawed surface. In order to simplify the calculation, the analysis herein uses through-wall stress profiles (x/t) in a similar fashion. The procedure in A-3320 of [8] is modified for the use of through-wall stress representation. This x/t approach is consistent with the methods prescribed in publications such as API-579 [10] and the 2015 Edition of ASME Section XI, A-3212 and A-3411(c). Note that the 2015 Edition of ASME Section XI, Appendix A specifies that Gi coefficient tables are applicable for both the x/a and x/t method.

The closed-form solution in K-4210 of [8] for KIp is generic for cylinder geometry, which is appropriate for the RV. However, preliminary results had determined it to be conservative for the nozzle weld locations. Therefore, the method described in A-3200 of [8], including crack face pressure, with an actual FEA pressure stress profile will be used for the SIF calculations.

The through-wall stress profile is represented as follows by a cubic polynomial:

1 4.593 1

6 Where:

a = flaw depth, [in]

t = wall thickness, [in]

l = flaw length, [in]

Ai = coefficients from the cubic polynomial stress profile, i= 0, 1, 2, 3 Ap = 0 for thermal KIt; Ap = internal vessel pressure for pressure KIp y = material yield strength, ASME temperature-dependent value is used, [ksi]

Gi = free surface correction factors from Table A-3320-1 of [8] for point 1, the deepest point PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-3 qy = plastic zone correction factor The plastic zone correction factor, qy, in this application is set to zero because K-4210 of [8] uses the effective flaw depth, ae, which includes ductile flaw extension and a plastic zone correction.

4.1.2 Nozzle Corner KI Closed Form Solution per [11]

The nozzle corner is the bounding location for the nozzle forging. The nozzle corner flaws are considered using the quarter circular crack in a quarter space crack geometry shown in Figure 4-1 for which solutions are available in [11]. Crack tip KI values are computed using:

2 4 0.723 0.551 0.462 0.408 2 3 Where:

= the stress perpendicular to the plane of the crack, and A0, A1, A2, and A3 are the polynomial coefficients for the stress profile x = the distance from the inner surface where the crack initiates a = crack depth X

FUN 10 - OUARTER,CIACULAR CRACK IN OUARiER-SPACE r.:-. 2a n,2 ~

K1* y n e [0.723 Ao+ 0.551 " ) A +- 0.462 \y-1 A2 + D.408( l n- I A3)

Figure 4-1: KI Solution for Quarter Circular Crack in Quarter Space [11, page 5]

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-4 4.1.3 Calculation of Japplied for Small-Scale Yielding The calculation of Japplied due to applied loads accounts for a materials elastic-plastic behavior.

When elastic fracture mechanics with small-scale yielding applies, Japplied may be calculated using crack tip SIF formulae with a plastic zone correction.

The effective flaw depth for small-scale yielding, ae, shall be calculated per K-4210 of [8]:

, [in]

Where, KIp and KIt are SIF due to pressure and thermal stresses, respectively.

Both axial and circumferential KIp and KIt are calculated the same way as KIp and KIt as discussed in Section 4.1.1, except that the flaw depth, a, is substituted with the effective flaw depth, ae. Then, the Japplied for small-scale yielding is calculated using the following formula:

1000 , [in-lb/in2]

Where:

E = E/(1- Q)2 ,[ksi]

E = Youngs modulus, [ksi]

Q = Poissons ratio = 0.3 4.1.4 Postulated Flaw The procedures for the Japplied calculation for Levels C/D described in K-5000 of [8] are the same as those for Levels A/B described in K-4000, except that the effect of cladding/base metal differential thermal expansion needs to be considered for Levels C/D per K-5210(a) of [8]. Therefore, stress data from the finite element model (FEM) with cladding is included for the Levels C/D evaluation.

Additional details of the postulated flaw requirements per K-2200, K-2300 and K-2400 are summarized in Section 2.2.1.

4.1.5 Weld Residual Stress The weld residual stress (WRS) is to be included for Level D to be consistent with the EMA performed in BAW-2192NP, Supplement 1 [13]. The normalized WRS profile is from [9, Section 4.1.3.4, Figure 30]. The WRS was directly added to the nozzle to shell weld FEA thermal stresses for the calculation of KIt.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-5 4.1.6 Stress Due to Mechanical Loads There are a total of four cases of mechanical piping and support load combinations: two cases for Levels A/B and two for Level D. Since the SF is only applicable to pressure, the mechanical stress is directly added to the FEA thermal stress. The maximum through-thickness mechanical stress of the design conditions is added to the corresponding thermal stresses. All KI and Japplied are calculated for all transient time points. The limiting Jappiled at the 0.1 inch flaw extension is reported.

4.1.7 Temperature Range for Upper Shelf Fracture Toughness Evaluations Upper-shelf fracture toughness is determined through use of Charpy V-notch impact energy versus temperature plots by noting the temperature above which the Charpy energy remains on a plateau, maintaining a relatively high constant energy level. Similarly, fracture toughness can be addressed in three different regions on the temperature scale, i.e., a lower-shelf toughness region, a transition region, and an upper-shelf toughness region. Fracture toughness of reactor vessel steel and associated weld metals are conservatively predicted by the ASME initiation toughness curve, KIc, in the lower shelf and transition regions. In the upper shelf region, for the Linde 80 and similar welds (i.e., Rotterdam welds), the upper shelf toughness curve, KJc, is derived from the upper-shelf J-integral resistance model described in Section 3.2. The upper-shelf toughness then becomes a function of fluence, copper content, temperature, and fracture specimen size. When upper-shelf toughness is plotted versus temperature, a plateau-like curve develops that decreases slightly with increasing temperature. Since the present analysis addresses the low upper-shelf fracture toughness issue, only the upper-shelf temperature range, which begins at the intersection of KIc and the upper-shelf toughness curves, is considered.

Transition region toughness is obtained from the ASME Section XI [8] equation for crack initiation, Section A-4200, KIc = 33.2 + 20.734exp[0.02(T-RTNDT)]

Using an RTNDT value of 208.3°F (page 5 of [5]) for a flaw depth of 1/10 the wall thickness where:

KIc = transition region toughness, ksi¥in T = crack tip temperature, °F Stress intensity factors (SIF) are converted to J-integrals by the plane strain relationship,

, where KJc is upper shelf region toughness, in ksi*¥inch, and J0.1 is the J integral resistance at a = 0.1 inch.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-6 4.2 APPLIED J-INTEGRAL RESULTS AND COMPARISON WITH J-R CURVES ALLOWABLES As discussed in Section 2.1, the cooldown transient is evaluated for Levels A/B. FEA through-wall stress profiles were fitted to 3rd order polynomials, and A-3200 of [8] was used for the calculation of KIt and KIp instead of the generic closed-form solution in Appendix K of [8]. As discussed in the methodology Section 4.1, this is more accurate and is an NRC approved method.

Unit pressure (1 ksi) FEA stress profiles were scaled to pressure transients and KIp was then calculated in the same manner as KIt using the 3rd order polynomial method. The crack face pressure was applied as discussed in Section 4.1.1. As discussed in Section 4.1.1, the double counting of the plastic zone correction was removed by setting the qy term in A-3200 of [8] to zero.

The plastic correction was accounted for in the ae term per K-4210 of [8].

4.2.1 Nozzle-to-Shell Welds Level A/B The Japplied values for a 0.1 inch flaw extension with pressure SF = 1.15 and SF =1.25 for Levels A/B are contained in Table 4-1. The Japplied at 0.1-inch flaw extensions (J1) for both inlet and outlet nozzle welds are below the J-R J0.1 = [ ]f, per Table 3-6. Therefore, the acceptance criteria in ASME Section XI, K-2200 (a)(1) [8] is satisfied. As shown in Figure 4-2 and Figure 4-3, the slope of Japplied is less than the J-R curve at the intersection of both curves (i.e.,

Japplied = J-R). Therefore, the stability acceptance criteria in ASME Section XI, K-2200 (a)(2) [8] is satisfied.

Table 4-1: Inlet and Outlet Nozzle Welds Levels A/B, Circumferential Flaw, Japplied a, c, e, f PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-7 a, c, e, f Figure 4-2: Inlet Nozzle Weld, Circumferential Flaw, Levels A/B Japplied vs. J-R, SF=1.25 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-8 a, c, e, f Figure 4-3: Outlet Nozzle Weld, Circumferential Flaw, Levels A/B Japplied vs. J-R, SF=1.25 4.2.2 Nozzle-to-Shell Welds Level D As discussed in Section 2.1, there is no applicable Level C transient. The Level D transient is the SLB. Per [2], the B&WOG model 6-B J-R mean curve is used for Level D loading as a best estimate representation of the toughness for the North Anna Unit 1 and 2 Rotterdam welds. The mean J-R curve values for the Rotterdam welds are listed in Table 4-3. Values of KIc and KIc2/E as a function of temperature are contained in Table 4-4. Temperature at which the mean J-R curve intersects KIc2/E is [ ]f, establishing the start of the upper shelf temperature range.

Figure 4-4 to Figure 4-7 combine the SLB transient Japplied, J-R and KIc2/E curves as follows:

1. The B&WOG Model 6-B mean J-R curve is used.

2. Figure 4-4 and Figure 4-6 present Japplied curves due to the Level D SLB transient, the mean J-R curve and KIc2/E curves as a function of crack tip temperature. The Japplied curve is truncated at temperature point of [ ]f (limiting or lowest temperature for upper shelf toughness. Figure 4-4 illustrates the inlet nozzle location case. Figure 4-6 illustrates the outlet nozzle location case. All points of the transient remain below the mean J-R curve.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-9

3. Figure 4-5 and Figure 4-7 show the Japplied and the mean J-R curve [

]f as a function of crack extension. Figure 4-5 presents the inlet nozzle Japplied at temperature of the crack tip temperature of [ ]a, c, e.

Figure 4-7 shows the outlet nozzle Japplied at the crack tip temperature of [ ]a, c, e.

These temperatures are conservative since Japplied is lower at the lowest upper shelf temperature. The slope of the Japplied is less than the slope of the mean J-R curve at the point of intersection, which demonstrates that the flaw is stable as required by ASME Section XI, Appendix K, K-3400.

The Japplied values at a 0.1 inch flaw extension with SF = 1 for Level D are contained in Table 4-2. Since the 1/10 of the wall thickness plus cladding exceeded 1 inch for all evaluated locations, the postulated flaw depth is 1 inch. As shown in Table 4-2, all applied J1 for the nozzle-to-shell welds are below the J0.1 of [ ]f. The acceptance criteria in ASME Section XI, K-2400 (a) [8] is satisfied.

Table 4-2: Inlet and Outlet Nozzle Welds Level D, Circumferential Flaw, Limiting Japplied a, c, e, f PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-10 Table 4-3: B&WOG Model 6-B Mean J-R Curve with a = 0.1 inch f

Table 4-4: KIc2/E Curve a, c, e, f PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-11 a, c, e, f Figure 4-4: Inlet Nozzle-to-Shell Weld, J-integral vs. Temperatu re PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-12 a, c, e, f Figure 4-5: Inlet Nozzle-to-Shell Weld, J-integral vs. Flaw Extension PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-13 a, c, e, f Figure 4-6: Outlet Nozzle-to-Shell Weld, J-integral vs. Temperature PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-14

-- a, c, e, f Figure 4-7: Outlet Nozzle-to-Shell Weld, J-integral vs. Flaw Extension Additionally, as discussed in Section (a), K-5300(b) also requires that the remaining ligament is not subject to tensile instability. Table 4-5 contains the necessary inputs and a sample calculation for tensile instability pressure using a flaw depth a=1.181 inch. Additionally, a range of flaw depths from 0.098 to 1.968 inches were calculated to be in excess of 10 ksi, which is significantly greater than the 2.5 ksi pressure expected during a SLB transient.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-15 Table 4-5: K-5300 Tensile Instability Check for RV Nozzle-to-Shell Weld a, c, e, f 4.2.3 Upper Shell Forging Level A/B The Japplied values for a 0.1 inch flaw extension with pressure SF = 1.15 and SF =1.25 for Level A/B are contained in Table 4-6. The J-R J0.1 values from Table 3-7 are interpolated to the respective actual crack tip temperatures of [ ]a, c, e in Table 4-6 to instead of using a conservative J0.1 from a higher temperature. Both the circumferential and axial flaw applied J1 are below the J0.1 at their respective temperatures. Therefore, the acceptance criteria in ASME Section XI, K-2200 (a)(1) [8] is satisfied. As shown in Figure 4-8 and Figure 4-9, the slope of Japplied is less than the J-R curve at the intersection of both curves (i.e., Japplied = J-R). Therefore, the stability acceptance criteria in ASME Section XI, K-2200 (a)(2) [8] is satisfied. Since the upper shell forging FEA stresses were taken from the thicker upper shell to the thinner intermediate shell region, it captured the stress concentration effect, therefore, the upper shell forging results are also applicable to the intermediate shell forgings.

Table 4-6: Upper Shell Forging Level A/B, Circumferential Flaw, Limiting Japplied a, c, e PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-16 a, c, e Figure 4-8: RV Upper Shell, Circumferential Flaw, Level A/B Japplied vs. J-R, SF=1.25 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-17 a, c, e Figure 4-9: RV Upper Shell, Axial Flaw, Level A/B Japplied vs. J-R, SF=1.25 4.2.4 Upper Shell Forging Level D The upper shell forging Japplied values for a 0.1 inch flaw extension with SF = 1 Level D are contained in Table 4-7. The J-R J0.1 at 600°F from Table 3-7 are used for conservatism. Both the circumferential and axial flaw applied J1 are below the J0.1. Therefore, the acceptance criteria in ASME Section XI, K-2400 (a) [8] is satisfied. As shown in Figure 4-10 and Figure 4-11, the slope of Japplied is less than the J-R curve at the intersection of both curves (i.e., Japplied = J-R). Therefore, the stability acceptance criteria in ASME Section XI, K-3400 [8] is satisfied. As shown in Table 4-8, the Level D, SLB transient internal pressure of 2.5 ksi is significantly less than the tensile instability pressures calculated per K-5300; therefore, the remaining ligament is not subjected to tensile instability. Since the upper shell forging FEA stresses were taken from the thicker upper shell to the thinner intermediate shell region, it captured the stress concentration effect, therefore, the upper shell forging results are also applicable to the intermediate shell forgings.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-18 Table 4-7: Upper Shell Forging Level D, Limiting Japplied a, c, e a, c, e Figure 4-10: RV Upper Shell, Circumferential Flaw, Level D Japplied vs. J-R PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-19 a, c, e Figure 4-11: RV Upper Shell, Axial Flaw, Level D Japplied vs. J-R Table 4-8: K-5300 Tensile Instability Check for RV Upper Shell a, c, e PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-20 4.2.5 Nozzle Forging Level A/B The nozzle corner is the limiting location for the nozzle forging due to the wall thickness and the stress concentration effect. The Japplied values for a 0.1 inch flaw extension with pressure SF =

1.15 and SF =1.25 for Level A/B are contained in Table 4-9. All the applied J1 values are less than the respective J0.1 from Table 3-6. Therefore, the acceptance criteria in ASME Section XI, K-2200 (a)(1) [8] is satisfied. As shown in Figure 4-12 to Figure 4-15, the slope of Japplied is less than the J-R curve at the intersection of both curves (i.e., Japplied = J-R). Therefore, the stability acceptance criteria in ASME Section XI, K-2200 (a)(2) [8] is satisfied.

Table 4-9: Nozzle Corner Level A/B, Limiting Japplied a, c, e PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-21 a, c, e Figure 4-12: Inlet Nozzle Corner, Circumferential Flaw, Level A/B Japplied vs. J-R, SF=1.25 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-22 a, c, e Figure 4-13: Outlet Nozzle Corner, Circumferential Flaw, Level A/B Japplied vs. J-R, SF=1.25 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-23 a, c, e Figure 4-14: Inlet Nozzle Corner, Axial Flaw, Level A/B Japplied vs. J-R, SF=1.25 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-24 a, c, e Figure 4-15: Outlet Nozzle Corner, Axial Flaw, Level A/B Japplied vs. J-R, SF=1.25 4.2.6 Nozzle Forging Level D The Japplied values for a 0.1 inch flaw extension for Level D are contained in Table 4-10. All the applied J1 for the nozzle forgings are less than the J0.1 of [ ]a, c, e from Table 3-6.

Therefore, the acceptance criteria in ASME Section XI, K-2400 (a) [8] is satisfied. As shown in Figure 4-16 to Figure 4-19, the slope of Japplied is less than the J-R curve at the intersection of both curves (i.e., Japplied = J-R). Therefore, the stability acceptance criteria in ASME Section XI, K-3400

[8] is satisfied. As shown in Table 4-11, the Level D internal pressure of 2.5 ksi is significantly less than the tensile instability pressures calculated per K-5300, therefore, the remaining ligament is not subjected to tensile instability.

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-25 Table 4-10: Nozzle Corner Level D, Limiting Japplied a, c, e PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-26 a, c, e Figure 4-16: Inlet Nozzle Corner, Circumferential Flaw, Level D Japplied vs. J-R, SF=1.0 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-27 a, c, e Figure 4-17: Outlet Nozzle Corner, Circumferential Flaw, Level D Japplied vs. J-R, SF=1.0 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-28 a, c, e Figure 4-18: Inlet Nozzle Corner, Axial Flaw, Level D Japplied vs. J-R, SF=1.0 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 4-29 a, c, e Figure 4-19: Outlet Nozzle Corner, Axial Flaw, Level D Japplied vs. J-R, SF=1.0 Table 4-11: K-5300 Tensile Instability Check for RV Nozzle Corner a, c, e PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 5-1 5 CONCLUSIONS The North Anna Units 1 and 2 RV nozzle-to-shell welds, nozzle forgings and upper shell forgings were evaluated for equivalent margins of safety per ASME Code Section XI [8]. The flaw extension and stability criteria of ASME Section XI, Appendix K are satisfied.

Levels A/B For all evaluated locations, the Japplied at 0.1-inch flaw extension with a structural factor (SF) of 1.15 for pressure and SF of 1.0 for thermal are less than the J-material at the 0.1-inch flaw extension. Therefore, the acceptance criteria in ASME Section XI, K-2200 (a)(1) [8] is satisfied.

The slope of Japplied (SF=1.25) is less than the J-material (J-R curve) at the intersection of both curves (i.e., Japplied = J-R). Therefore, the stability acceptance criteria in ASME Section XI, K-2200 (a)(2) [8] is satisfied.

Level D For all evaluated locations, the Japplied at 0.1-inch flaw extension with a SF of 1.0 are less than the J-R at the 0.1-inch flaw extension. Therefore, the acceptance criteria in ASME Section XI, K-2400 (a) [8] is satisfied. The slope of Japplied is less than the J-R curve at the intersection of both curves (i.e., Japplied = J-R). Therefore, the stability acceptance criteria in ASME Section XI, K-3400 [8] is satisfied. All flaws evaluated for Level D assumed 1/10 of the wall thickness (including cladding and limited to 1 inch) plus a 0.1 inch flaw extension. The results demonstrate that flaw growth is stable at less than 75% of the wall thickness since the applied J-integral intersects the mean J-integral resistant curve at a small fraction of the thickness. This satisfies the 75% of wall thickness requirement per K-2400 (c). Additionally, the maximum Level D internal pressure is less than the tensile instability pressures calculated per K-5300 (b) for all evaluated locations and flaws.

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 6-1 6 REFERENCES

1. BAW-2192, Revision 0, Supplement 1P-A, Revision 0, Low Upper-Shelf Toughness Fracture Mechanics Analysis of Reactor Vessels of B&W Owners Reactor Vessel Working Group for Levels A & B Service Loads, December, 2018.

2. BAW-2192, Revision 0, Supplement 2P, Revision 0, Low Upper-Shelf Toughness Fracture Mechanics Analysis of Reactor Vessels of B&W Owners Reactor Vessel Working Group for Levels A & B Service Loads.

3. NUREG/CR-5729, Multivariable Modeling of Pressure Vessel and Piping J-R Data, May 1991.

4. Code of Federal Regulations, 10 CFR Part 50, Appendix G, Fracture Toughness Requirements, U.S. Nuclear Regulatory Commission, Washington D.C., Federal Register, Volume 77, No. 14, January 23, 2012.

5. North Anna Power Station Updated Final Safety Analysis Report, Revision 55.

6. Regulatory Guide 1.161, Evaluation of Reactor Pressure Vessels with Charpy Upper-Shelf Energy Less than 50 ft-lb, U.S. Nuclear Regulatory Commission, June 1995.

7. ASME Boiler and Pressure Vessel Code,Section III, 1968 Edition, with Addenda up to and including Winter 1968.

8. ASME Boiler and Pressure Vessel Code,Section XI, 2013 Edition.

9. Fracture Analysis of Vessels - Oak Ridge FAVOR, v05.1, Computer Code: Theory and Implementation of Algorithms, Methods, and Correlations, ORNL/NRC/LTR-05/18 (ADAMS Accession Number ML063350323).

10. API 579-1/ASME FFS-1, Fitness-For-Service, Annex C, Compendium of Stress Intensity Factor Solutions, June, 2016.

11. S. A. Delvin and P. C. Riccardella, Fracture Mechanics Analysis of JAERI Model Pressure Vessel Test, ASME Paper No. 78-PVP-91, Proceedings of the 1978 ASME Pressure Vessels and Piping Conference, June 25-30, 1978, Montreal, Quebec, Canada.

12. NRC SE Report, Safety Assessment of Report WCAP-13587, Revision 1, Reactor Vessel Upper Shelf Energy Bounding Evaluation For Westinghouse Pressurized Water Reactors, September 1993, April 21, 1994.

PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY 6-2

13. NRC SE Report, Final Safety Evaluations for BAW-2192, Supplement 1NP, Revision, Low Upper-Shelf Toughness Fracture Mechanics Analysis of Reactor Vessels of B&W Owners Reactor Vessel Working Group for Level A&B Service Loads and BAW-2178, Supplement 1NP, Revision 0, Low Upper-Shelf Toughness Fracture Mechanics Analysis of Reactor Vessels of B&W Owners Reactor Vessel Working Group for Level C&D Service Loads, ML19106A196, April 29, 2019.

PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-1 APPENDIX A : CORRESPONDENCE WITH U.S. NRC REGARDING THE REVIEW OF PWROG-19047-P, REVISION 0 PWROG-19047-NP-A August, 2021 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-2 Program M:magemcnt Office 20 International Drive PWR: Owners Group Windsor, Connecticut 06095 PWROG-19047-P/NP, Revision 0 Project Number 99902037 May 27, 2019 OG-20-167 U.S. Nuclear Regulatory Commission Document Control Desk 11555 Rockville Pike Rockville, MD 20852

Subject:

PWR Owners Group Submittal of PWROG-19047-P/NP, Revision O, "North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis" (PA-MSC-1481)

Reference 1: NUREG/CR-5729, "Multi variable Modeling of Pressure Vessel and Piping J-R Data," May 1991.

The purpose of this letter is to submit PWROG-19047-P/NP, Revision 0, North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis." to support the North Anna Units 1 and 2 Subsequent License Renewal (SLR) application as requested during the meeting held on April 9, 2020, between Dominion and the NRC (Accession Number ML20104A039 contains the NRC meeting summary).

The purpose of this topical report (TR) is to document the equivalent margins analysis (EMA) for the North Anna Units 1 and 2 reactor vessel (RV) inlet and outlet nozzle Rotterdam welds, nozzle forgings and nozzle belt forgings (a.k.a., upper shell forgings).

These locations were chosen due to the potential that their upper-shelf energy (USE) maybe less than the 50 ft-lb limit at 80-years (72 EFPY) for SLR. Two forging locations were determined to be less than or equal to the 50 ft-lb limit at 80-years (72 EFPY) and the equivalent margin analysis (EMA) for these locations utilized the multi variable model for RPV base metal contained in Reference 1.

The PWROG requests that the NRC review the TR for the two forging locations that were determined to be less than or equal to the 50 ft-lb limit at 80-years (72 EFPY).

As Enclosures 1 and 2 contain information proprietary to Westinghouse Electric Company LLC ("Westinghouse") and Framatome Inc., the information contained herein is supported by two Affidavits: one each signed by Westinghouse and Framatome Inc., the owners of the information. The Affidavits set forth the basis on which the information may be withheld from public disclosure by the Nuclear Regulatory Commission ("Commission")

and addresses with specificity the considerations listed in paragraph (6)(4) of 10CFR Section 2.390 of the Commission' s regulations.

• • • This record was final approv ed on 8/26/2020 1:59:44 PM. (This statement was added by the PRIME system upon ~s validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-3 U.S. Nuclear Regulatory Commission May 27, 2020 Document Control Desk Page 2 of3 OG-20-167 Accordingly, it is respectfully requested that the information which is proprietary to Westinghouse and/or Framatome Inc. be withheld from public disclosure in accordance with 10 CFR Section 2.390 of the Commission's regulations. Each affidavit should be consulted to identify the appropriate justifications for withholding of the respective information.

Correspondence with respect to the copyright or proprietary aspects of the items listed above or the suppotting Westinghouse Affidavit should reference CAW-20-5039 and should be addressed to Camille T. Zozula, Manager, Infrastructure & Facilities Licensing, Westinghouse Electric Company, 1000 Westinghouse Drive, Suite 165, Cranberry Township, Pennsylvania 16066.

Correspondence with respect to the copyright or proprietary aspects of the item listed above or the supporting Framatome Inc. Affidavit should be addressed to Philip Opsal, OF-34, Framatome Inc.,

3315 Old Forest Road, Lynchburg, VA 24501.

TR Classification: As discussed above, this TR addresses the multivariable modeling of the Pressure Vessel per Reference 1 for the two forging locations at or below the 50 ft-lb limit at 80-years (72 EFPY). Additionally, the J-integral resistance Model 6B is used for some locations where the upper shelf energy was determined to be greater than 50 ft-lbs. These were evaluated proactively in this EMA for asset management considerations.

Specialized Resource Availability: This TR is being submitted to the NRC for review and approval so that the NRC approved version can be utilized for performing plant-specific evaluations of the equivalent margins analyses.

This letter transmits PWROG-19047-P Revision O (Enclosure 1), and PWROG-19047-NP (Enclosure 2). Notarized Affidavits for Withholding proprietary information are provided as Enclosures 3 and 4.

Applicability: This TR is applicable to the reactor vessels for North Anna Units 1 and 2 add discussed in the TR.

The PWROG requests that the NRC complete their review of the TR by August 15, 2020.

Correspondence related to the non-proprietary transmittal should be addressed to:

Mr. W. Anthony Nowinowski, Program Manager PWR Owners Group, Program Management Office Westinghouse Electric Company 1000 Westinghouse Drive, Suite 172 Cranberry Township, PA 16066

-* This record was final approved on 8/26/2020 1:59:44 PM . (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-4 U.S. Nuclear Regulatory Commission May 27, 2020 Document Control Desk Page 3 of3 OG-20-167 If you have any questions, please do not hesitate to contact me at (602) 999-2080 or Mr. W. Anthony Nowinowski , Program Manager of the PWR Owners Group, Program Management Office at (412) 374-6855.

Sincerely yours, Michael Powell, Chief Operating Officer and Chairman PWR Owners Group MP:JPM:am Enclosure 1: (One Copy) PWROG-19047-P, Revision 0, "North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis" (Proprietary)

Enclosure 2: (One copy) PWROG-19047-NP, Revision 0, "North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis" (non-propri etary)

Enclosure 3: Westinghouse Affidavit for Withholding Proprietary Information, CAW-20-5039 Enclosure 4: Framatome Affidavit for Withholding Proprietary Information cc: PWROG PMO PWROG Steering and Management Committee L. Fields, US NRC C. Tomes, Dominion P. Aitken, Dominion J. Andrachek, Westinghouse T. Zalewski, Westinghouse G. Hall, Westinghouse S. Rigby, Westinghouse D. Page Blair, Framatome N. Ashok, Framatome M. Rinckel , Framatome Electronically Approved Records are Authenticated in PRIME

• • • This record was final approv ed on 8/26/2020 1:59:44 PM. (This statement was added by the PRIME system upon ~s validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-5 Program Management Office 1000 Westinghouse Drive, Suite 380 Cranberry Township, PA 16066 PWR: Owners Group PWROG-19047-P/NP, Re ision 0 Docket 99902037 Project 694 December 3 2020 00-20-284 U.S. Nuclear Regulato1y Commission Document Control Desk 11555 Rockv ille Pike Rockvi lle, MD 20852

Subject:

PWR Owners Group Transmittal of the Response to Request for Additional Information, RAls 1-7 Associated with PWROG-19047-P P, Revision O, "Noi*th Anna Units 1 and 2 Reactoi* Vessels Low Uppe1*-Shelf Frnctw*e Toughness Equivalent Margin Analy is" (PA-MSC-1481)

References:

I. Letter 00 167, Submittal of PWR00-1 9047-P/NP, Revi ion 0, " North An na Units I and 2 Reactor Vessels Low Up per-ShelfFracture Toughness Eq uivalent Margi n Analysis",

PA-M C- 1519, dated May27, 2020

2. Emai l from the NRC (Fields) to the PWROO (Holderba um), Request for Add itional l nforma tion, RAis l -7, RE: PWROG-1 9047-P/NP, Revi *ion 0, 'North Anna Unit l and 2 Reactor Vessels Low Upper-Shel f Fracture Toughness Equivalent Margin Analysis",

dated eptember 25, 2020 On May 27, 2020, in acco rdance with the Nuclear Regulatory Commission (NRC) To pica l Report (TR) program fo r review and acceptance, the P ressurized Wa ter Reactor Owners Group (PWROO) req uested forma l NRC review and approval ofPWR00- 19047-P & NP, Revision Ofor reforenci ng in regul a!ory actions (Reference l ). The NRC taff has determined that additional info rmation is needed to complete the review per the email dated eptember 25, 2020 (Reference 2).

nclosure 1 to this letter provides forma l responses to NRC RAi s 1-7 (Reference 2) associated

"~th PWROG- 19047-P/NP, North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysi " .

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-6 U.S. Nuclear Regulatory Commission December 3, 2020 00-20-284 Page 2 of2 Correspondence related to this transmittal should be addressed lo:

Mr. W. Anthony Nowinowski , xecutive Director PWR Owners Group, Program Management Office Westinghouse lectric Company 1000 Westinghouse Drive Cranberry Township, PA 16066 If you have any questions, plea *e do not hesitate lo contact me at (434) 832-2382 or Mr. W.

Anthony Nowinowski Program Manager of the PWR Owners Group, Program Management Office at (4 12) 374-6855.

inee rely you rs, Michael Powell Chi ef Operating Officer & Chairman Pressurized Water Reactor Ov,rners Group MP:JPM:am cc: PWROG PMO C. Tomes, DOM D.Knee, DOM P Aitken, DOM T. Hanna, DOM M.Post DOM L. Fields, US NRC J Andrachek, Westinghouse T. Zalewski , Westinghouse G. Hall Westinghouse S. Rigby, Westing house

• • nclosure I. LTR-SDA-20-082, Revi ion O (nonproprietary), RAis 1-7 Responses for PWROG-19047-P!NP, Revision O(PA-M C-1481)

Electronically Approl'ed Records are Authenticated in PR/NIE PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-7 Westinghouse Non-Proprietary Class 3 Page 1 of 13 Our ref: LTR-SDA-20-082, Rev. 0 November 19, 2020 To: Thomas Zalewski Date: November 19, 2020 cc: Stephen P. Rigby From: Gordon Z. Hall Yourref: NIA Ext: (860)731-6114 Our ref: LTR-SDA-20-082, Rev. 0

Subject:

Westinghouse Response to U.S. NRC Request for Additional Information (RAI) for PWROG-19047-P/NP, Rev. 0

References:

I. U.S. NRC Request for Additional Information for Pressurized Water Reactor Owners Group Topical Report, PWROG-19047-P/NP, Revision, 0, "North Anna Units 1 and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis," Docket No. 99902037; EPID L-2020-TOP-0028.

2. Topical Report, BAW-2192, Revision 0, Supplement lP-A, Revision 0, "Low Upper-Shelf Toughness Fracture Mechanics Analysis of Reactor Vessels of B&W Owners Reactor Vessel Working Group for Levels A & B Service Loads," December 2018.

3. ASME Boiler and Pressure Vessel Code,Section XI, 2013 Edition.

4. Topical Report, PWROG-18005-NP, Rev. 2, "Determination ofUnirradiated RTNoT and Upper-Shelf Energy Values of the North Anna Units 1 and 2 Reactor Vessel Materials," September 2019.

5. Topical Report, PWROG-17090-NP-A, Rev. 0, "Generic Rotterdam Forging and Weld Initial Upper-Shelf Energy Determination," January 2020. [ADAMS Accession Number ML20024E238]

6. U.S . Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, Regulatory Guide 1.99, Revision 2, "Radiation Embrittlement of Reactor Vessel Materials," May 1988. [ADAMS Accession Number ML003740284]

7. Westinghouse Report, WCAP-18363-NP, Rev. 1, "North Anna Units 1 and 2 Heatup and Cooldown Limit Curves for Normal Operation," March 2020.

8. WestinghouseReport, WCAP-18364-NP,Rev. 1, "North Anna Units 1 and2 Time-Limited Aging Analysis on Reactor Integrity for Subsequent License Renewal (SLR)," March 2020.

9. Westinghouse Report, WCAP-18015-NP, Rev. 2, "Extended Beltline Pressure Vessel Fluence Evaluations Applicable to North Anna 1 & 2," September 2018.

10. U.S . Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, Regulatory Guide 1.190, "Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence,"

March 2001. [ADAMS Accession Number ML010890301]

11. Westinghouse Report, WCAP-14040-A, Rev. 4, "Methodology Used to Develop Cold Overpressure Mitigating System Setpoints and RCS Heatup and Cooldown Limit Curves WOG Programs: MUHP-5073 MUHP-3073," August 2005 .

12. North Anna Power Station Units 1 and 2 Application for Subsequent License Renewal, August 2020. [ADAMS Accession Number ML20246G696]

13. Topical Report, PWROG-19047-P, Rev. 0, "North Anna Units 1 and 2 Reactor Vessels LowUpper-ShelfFracture Toughness Equivalent Margin Analysis," May 2020.

14. NUREG/CR-5729, "Multivariable Modeling of Pressure Vessel and Piping J-R Data," May 1991.

15. Westinghouse Report, WCAP-16333-NP, Rev. 0, "Fracture Toughness Testing of Compact Tension Specimens from Watts Bar Unit 1 Surveillance Capsule X," October 2004.

• • • This record was final approved on 11/20/2020 5:34:16 PM. (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-8 Westinghouse Non-Proprietary Class 3 Page 2 of 13 Our ref: LTR-SDA-20-082, Rev. 0 November 19, 2020

Background

By letter dated May 27, 2020 (Agencywide Document Access and Management System (ADAMS)

Accession No. ML20149K668) the Pressurized Water Reactor Owner's Group (PWROG) submitted Topical Report (TR) PWROG-1 9047-Proprietary (P)'Non-Proprietary (NP), Revision (Rev.) 0, "North Anna Units I and 2 Reactor Vessels Low Upper-Shelf Fracture Toughness Equivalent Margin Analysis," ((ADAMS) Accession No. ML20149K670) for NRC review and approval.

The purpose of the TR is to document the equivalent margins analysis (EMAs) for the North Anna Units I and 2 reactor vessel (RV) inlet and outlet nozzle Rotterdam welds, nozzle forgings and nozzle belt forgings (a.k.a., upper shell forgings) to demonstrate compliance with Section IVA I of Appendix G to 10 CFR Part 50 "Fracture Toughness Requirements." These locations were chosen for their upper-shelf energy (USE) potentially falling below the 50 ft-lb limit at 80-years (72 EFPY) for subsequent license renewal (SLR). The NRC staff (the staff) determined it needs additional information to complete its review of the TR.

Regulatory Basis Title 10 of the Code of Federal Regulations (10 CFR), Part 50.60, "Acceptance criteria for fracture prevention measures for light water nuclear power reactors for normal operation," is the governing regulation for Reactor Vessel Charpy Upper-Shelf Energy of the reactor vessel. I OCFR 50.60 imposes fracture toughness and material surveillance program requirements, which are set forth in Appendices G, "Fracture Toughness Requirements, " and H, "Reactor Vessel Material Surveillance Program Requirements," to 10 CFR Part 50.

Section IV.A I.a of Appendix G to I O CFR Part 50 sets forth requirements that the reactor vessel beltline materials must have Charpy upper-shelf energy in the transverse direction for base material and along the weld for weld material according to the ASME Code, ofno less than 75 ft-lb (102 J) initially and must maintain Charpy upper-shelf energy throughout the life of the vessel of no less than 50 ft-lb (68 J), unless it is demonstrated in a manner approved by the Director, Office of Nuclear Reactor Regulation, that lower values of Charpy upper-shelf energy will provide margins of safety against fracture equivalent to those required by Appendix G of Section XI of the ASME Code. Furthermore, this analysis must use the latest edition and addenda of the ASME Code incorporated by reference into IO CFR 50.55a(b X2) at the time the analysis is submitted.Section IV.A l .c of Appendix G to I O CFR Part 50 sets forth requirements that the analysis for satisfy ing the requirements of section IV.A I of Appendix G must be submitted, as specified in § 50.4, for review and approval on an individual case basis at least three years prior to the date when the predicted Charpy upper-shelf energy will no longer satisfy the requirements of section IV.A I of this appendix, or on a schedule approved by the Director, Office of Nuclear Reactor Regulation. The requirements in these sections of Appendix G to 10 CFR Part 50 and the ASME Code, therefore, form the regulatory bases for the staffs requests for additiona l information (RAis).

REQUESTS FOR ADDITIONAL INFORMATION:

• • • This record was final approved on 11/20/2020 5:34 :16 PM. (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-9 Westinghouse Non-Proprietary Class 3 Page 3 of 13 Our ref: LTR-SDA-20-082, Rev. 0 November 19, 2020

RAI 01

Issue Section 2.1, Regulatory Requirements, " ofP WROG-1904 7-P states, in part, the coo/down transient for North Anna Units 1 and 2 with a constant pressure o/2750 psia assumed throughout the transient bounds all Levels AIB conditions. Further, it states that the Level CID transient selection is based on the guidance in Regulatory Guide 1.161, "Evaluation ofReactor Pressure Vessels with Charpy Upper-ShelfEnergy Less than 50ft-lb, "(RG 1.161) and explained that the Level D transient is the steam line break (SLB). Section 4.1 of PWROG-19047-P indicates that only the SLB transient is specified for Level D conditions.

The staff noted that K-1100 ofAppendix K to Section XI of the ASME Code states, in part, that "[a]ll specified design transients for the reactor vessel shall be considered. " The staff reviewed North Anna Updated Final Safety Analysis Report Table 5.2-4 (ADAMS Accession No. MLI 1287A241) and noted that beyond the "steam pipe break" transient there are additional Service Level D conditions (i.e.,

Faulted Conditions) that are applicable to the current licensing basis for North Anna, Units 1 and 2, such as the "Main reactor coolant pipe break" and Design-basis earthquake. " Section 4 ofRG 1.161 states that selection of the limiting transients for Service Levels C and D is a key aspect of evaluating the integrity ofreactor pressure vessels that contain materials with Charpy upper-shelfenergy less than 50ft-lb.

The staff determined that it is not clear how the consideration of only the coo/down transient with a constant pressure of 2750 psia assumed throughout the transient, and the SLB transient satisfies K-1100 of AppendixK to SectionXI oftheASMECode.

NRCRequest a) Provide the Justification for the selection of the coo/down transient for North Anna, Units 1 and 2, with a constant pressure of 2750 psia assumed throughout the transient satisfies K-1100 of Appendix K to Section XI of the ASME Code for Service A and B transients.

b) Provide the Justification for the selection of the SLB transient for North Anna, Units 1 and 2, satisfies K-1100 ofAppendix K to Section XI of the ASME Code for Service D transients.

Response

(a) The ASME Section XI, K-1100 text regarding "design transients for the reactor vessel" is interpreted to mean the design transients defined by the ASME Section III Certified Design Specification. Considering the normal and upset conditions listed in the North Anna UFSAR, Table 5.2-4, the cooldown transient for North Anna Units 1 and 2 is chosen to bound all Levels A/B service loading conditions with a constant accumulation pressure of2750 psia, i.e. 1.1 times design pressure per ASME Section XI, K-1300 and K-4220 [3]. Additionally, the plant cooldown transient with a !00°F/hour cooldown rate is consistent with K-4210 (c), where the simplified equation of thermal load, K1t using a CR (cooling rate) of 100°F/hour for Level A/B. The above approach is consistent with BAW-2192, Revision 0, Supplement IP-A, Revision O [2].

(b) The Level CID transient selection is based on the guidance in Regulatory Guide 1.161, Section 4, "TRANSIENT SELECTION" Plant-specific transient is used for the North Anna EMA There is no applicable emergency (Level C) transient defined in the Westinghouse RV design specification, and the only Level D transient is the steam line break (SLB). As discussed in UFSAR Section 5.2.4, the North Anna Units 1 and 2 Leak-Before-Break (LBB) analysis was performed on the main coolant loop piping and was approved by the NRC on August 31, 1999. Therefore, a main reactor coolant pipe break need not to be considered. However, for conservatism, the Level D condition included the pipe rupture and Safe Shutdown Earthquake (SSE) loads on the nozzle and support pad for the EMA.

• • • This record was final approved on 11/20/2020 5:34 :16 PM. (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-10 Westinghouse Non-Proprietary Class 3 Page 4 of 13 Our ref: LTR-SDA-20-082, Rev. 0 November 19, 2020 RAI02 Issue Section 3.2, J-Integral Resistance Models" ofPWROG-19047-P states that "the maximum reported copper content and the fluence value at the nozzle-to-shell weld is utilized" as summarized in Table 3-3 of PWROG-19047-P. However, the staff noted that the supporting reference from the current licensing basis for this assumption for copper content at the nozzle-to-shell weld and a description of the methodology for determining the neutronjluence at the nozzle-to-shell weld was not provided.

NRCRequest a) Provide a reference to the current licensing basis document that supports the copper content value used in PWROG-19047-P that demonstrates its applicability for the nozzle-to-shell welds at North Anna, Units 1 and 2.

b) Provide the basis for the neutronjluence value used inPWROG-19047-P to bound the nozzle-to-shell welds for North Anna, Units 1 and 2.

i. Provide an explanation for the methodology used to determine this projected neutron fluence value for the North Anna, Units 1 and 2, nozzle-to-shell welds at 80-years (72 Effective Full Power Years (EFPY) for subsequent license renewal).

ii. Describe how this methodology either (1) adheres to the guidance contained NRC Regulatory Guide 1.190, "Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence" (ADAMS Accession No. A1L010890301); or (2) is otherwise suitably accurate or bounding for the downstream modeling. Furthermore, provide additional justification regarding how the calculational methods used to estimate fluence were suitable for application to the nozzle elevation

Response

(a) The reference for the copper content is PWROG-18005-NP, Rev. 2 [4]. Please refer to Table 9 and 10 in PWROG-18005-NP. Note that the Cu value is the generic value in Regulatory Guide 1.99, Rev. 2 [6J. The weld heat and type for these nozzle-to-shell welds could not be determined for North Anna Unit 1, only that these welds were fabricated by Rotterdam. Consistent with the NRC approved PWROG-17090-NP-A [5J, when the weld heat and type are not known for a Rotterdam fabricated weld, the generic value from Regulatory Guide 1.99 can be used for Cu content.

(b) (i)

The reactor vessel fluence values utilized for the RVI evaluations in WCAP-18363-NP [7J and WCAP-18364-NP [SJ are from WCAP-18015-NP [9J which uses DORT transport models based on methodologies consistent with the guidance in Regulatory Guide 1.190 [ 1OJ. These methodologies have been approved by the U.S. Nuclear Regulatory Commission (NRC) and are discussed in detail in WCAP 14040-A, Rev. 4 [ 11].

(ii)

Regulatory Guide 1.190 [ 1OJ contains an allowable neutron fluence uncertainty of +/- 20% for the reactor vessel beltline region, but it does not define an allowable neutron fluence uncertainty for the extended beltline region of the reactor vessel. Currently, there is no NRC regulatory guidance for calculating reactor pressure vessel extended beltline fluences. Therefore, the same methodology that was used for the beltline region was used for the extended beltline region. In order to demonstrate the acceptability of the results, a margin assessment was performed and summarized

• • • This record was final approved on 11/20/2020 5:34:16 PM. (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-11 Westinghouse Non-Proprietary Class 3 Page 5 of 13 Our ref: LTR-SDA-20-082, Rev. 0 November 19, 2020 in the Section 4.2.1 of the North Anna SLR Application [12]. The assessment concluded the following with respect to the EMA that:

• The maximum projected fluence values of the North Anna Units 1 and 2 reactor vessel inlet/outlet nozzles (3 .14 x I 017 n/cm2 corresponding to the nozzle-to-shell weld location) could increase by 60% before exceeding the fluence value utilized in the EMA for SLR (5 x 1018 n/cm2 ). As shown in Tables 4.2.2-3 and 4.2.2-4 of the North Anna SLR Application

[12], the limiting USE nozzle for both Units 1 and 2 has a projected fluence value of 1.20 x 1017 n/cm2 and would need to increase by a factor of greater than 4 prior to reaching the fluence utilized in the EMA.

• As shown in Tables 4.2.1-1 and 4.2.1-2 of the North Anna SLR Application [12], the maximum projected fluence values of the North Anna Units 1 and 2 inlet and outlet nozzle to shell welds (3. 14 x 1017 n/cm2 ) would need to increase by 3 times the current value before exceeding the fluence value utilized in the EMA for SLR (1 x 10 18 n/cm2 ).

• • • This record was final approved on 11/20/2020 5:34:16 PM. (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-12 Westinghouse Non-Proprietary Class 3 Page 6 of 13 Our ref: LTR-SDA-20-082, Rev. 0 November 19, 2020 RAI03 Issue Section 3.2, J-Integral Resistance Models" of PWROG-1 9047-P states the J-R curves for the RV nozzle and shell forgings were developed in accordance with NUREGICR-5729, lvfultivariable Modeling ofPressure Vessel and Piping J -R Data, " Table 11, Charpy model without flµence. Further, it states that the Charpy model is applicable to North Anna nozzle and shell forgings because they are bounded by the range of explanatory variables (fiuence, copper conten0 etc.) used to develop the J -R model. [emphasis added/

The staff noted that NUREGICR-5729 indicates that only two types of models were developed for the reactor pressure vessel base metals database (i.e., a Charpy model and a pre-irradiation Charpy (CVNp) model) and since copper content (Cu) was not measured for much of the base metal database, a Cu-jluence model was not investigated Furthermore, Table 11 ofNUREGICR-5729 does not appear to incorporate Cu and neutronfluence as variables for the Charpy Model for RPV Base Metals. Given this discrepancy in PWR OG-1 9047-P, it is not clear to the staff how the PWR OG determined that the North Anna, Units 1 and 2, nozzle and shell forgings are bounded by the explanatory variables used in the development of the model it selected.from NUREGICR-5729.

NRCRequest a) Clarify the discrepancy in PWROG-1 9047 with regard to the explanatory variables (e.g., copper andfluence) ofNUREGICR-5729 model that are used in the EMAsfor North Anna, Units 1 and 2.

b) Provide the basis (with reference to the applicable current licensing basis documents) that the N orthAnna, Units 1 and 2, nozzle and shell forgings are bounded by the range of explanatory variables used to develop the J -R model (i.e. , Table 11 ofNUREGICR-5729).

Response

As stated in Section 3.2 of PWROG-1 9047 [13], the NUREG/CR-5729 [14], Table 11 , Charpy model was used. This model does not include flu ence and Cu as input parameters directly. However, values bounding the projected 80-year USE va lues contained in WCAP-18364-NP [8] were used for the CVN (Charpy) input. Note that WCAP-1 8364-NP was submitted to NRC for the North Anna SLR application. The projected 80-year values calculated in WCAP-18364-NP [8] include fluence and Cu as inputs consistent with Regulatory Guide 1.99 [6]. The projected SLR USE values are shown in Table 1 compared to the CVN values used to calculate the J-R curves using the NUREG/CR-5729, Table 11 Charpy model.

Ta bl e 1 : P ro.1ecte

. d USE vs. CVNfior Ch arpy Md o eIJR -

Limiting Projected SLR USE CVN values used to calculate Reactor Vessel WCAP-18364-NP [8] J-R curves used in Material Unitl Unit2 PWROG-19047-P [13]

(ft-lbs) (ft-lbs) (ft-lbs)

Inlet and Outlet Nozzle 50.0 53.1 48.2 Forgings Intermediate Shell 63 .7 48.2 47.5 Forgings The North Anna Units I and 2 reactor pressure vessels (RPV) were fabricated by Rotterdam Dockyard Company . Measured J-R curves for two other forgings from Rotterdam fabricated RPVs were compared to the NUREG/CR-5729, Table 11 Charpy model estimated J-R curves to va lidate the model for Rotterdam forgings. The Watts Bar Unit 1 surveillance forg ing from Capsules W

• • • This record was final approved on 11/20/2020 5:34 :16 PM. (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-13 Westinghouse Non-Proprietary Class 3 Page 7 of 13 Our ref LTR-SDA-20-082, Rev. 0 November 19, 2020 and X was J-R tested and reported in WCAP-1 6333-NP [15]; the normalized results are shown in Figure I. The predicted USE values for Watts Bar Unit 1 Capsules W and X determined in accordance with Regulatory Guide 1.99 [6] are 45.9 ft-lbs and 44.0 ft-lbs respectively. The predicted NUREG/C R-5729, Table 11 Charpy model at standard conditions is also shown in Figure I. The standard conditions and normalization procedure defined in NU REG/C R-5729 was used. An unirradiated nozzle dropout A508 Class 2 forging from a different Rotterdam fabricated RPV was also J-R tested by Westinghouse in 1992 . This forging had a USE of 100 ft-lbs. The predicted NUREG/CR-5729, Table 11 Charpy model at standard conditions is shown in Figure 2 and Figure 3, which are compared to the normalized 300°F and 550°F test data respectively. Based on the compa,ison of measured data from Rotterdam fo rgi ngs to the NUREG/C R-5729, Table I I Charpy model used for estimating J-R curves in PWROG -1 9047, th e model adequately represents the measured data, therefore, the model is deemed acceptable to be used in the analysis. The inadiated Rotterdam forging has a u value (0. 155%) that is rep resentative of th e 01t h Anna Units 1 and 2 forgings and has the highest flu ence avai lable for a J-R tested Rotterdam fo rging in the U .S.

The U SE values (44.0 45.9 and 100 ft-lbs) used as inputs to check the Charpy model against measured J-R data bour1d those used in the EMA .

The statement in the RA! can be clarified as follows "The Charpy model is applicable to the North Arma Unit.s 1 and 2 nozzle and shell forgings because the J-R model was validated against representative Rotterdam forg ings with measured J-R dat,a." The Topical Repo,t PWROG -19047-p (and -NP) will be revised as such.

4.000 3.500 3.000

• Jnorm_WT9

)( Jncnn_\VTIO X Jncnn_ WTII

• • • • • • • • -*..,*-**********

• Juonn_wru 1.500

~**

• • ......~ ..~}~....... ... ~.................

o ln<<1l\...WTl4 Jnonu WTIS

.... * ****** J1e, ~ff

• 0.7-19

- - I x, tF

• IO 1.000 0.02 000 0.06 008 0 10 012 0" 0.16 0 18 010 Flaw E:1:ttt1.slo11 (lo)

Figure l: harpy M odel J-inlcgra l at S landard ond ilions Vs. ormalizcd Walts Bar Unil l Oala

... This record was fina l approved on 11/20/2020 5:34:16 PM. (Th is statement was added by the PRIM E system upon ~s validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-14 Westinghouse on-Proprietary Class 3 Page 8 of 13 Our ref: LTR-SOA-20-082, Rev. 0 ovember 19, 2020 6.0

+ Jnam_300F

- J,cu390'F 5.0 4.0 N +

'=

i 3.0

~ +

...,'0 ++

.;.+ +++..,+

2.0 i** ***

++:.: * +* ... -+

t....

\'i"'4+

+

+

r~

1.0 fj:.

!+

0.0 0.00 0.05 0.10 0.15 0.20 0.25 0.30 Fla,,. Ei:lenslon (in)

Figure 2: NUREG/CR-5729 Charpy Model vs. 'ormalized Measured Data at 300°F 6.0 6 Jnom,_5SOF

- Js<o1J90"F 5.0 +---------"'-- - - - - - - - - - - - - - - - - - - - - - -

6 6

6 4,0 + - - - - - - - - - - - - - - - - - - - - - - - -~ - - - - - -~6~ - - -

0,0 Ir-----~-----------~----~-----------

0.00 0.05 0.10 0.15 0.20 0.25 0.30 l'Llw Emn,lo* (lo)

Figure 3: NUREG/CR-5729 Charpy Model vs. ormalizcd Measured Data at 550°F

-This record was final approved on 11/2012020 5:34 :16 PM. (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-15 Westinghouse Non-Proprietary Class 3 Page 9 of 13 Our ref: LTR-SDA-20-082, Rev. 0 November 19, 2020 RAI04 Issue Section 1, "Introduction" ofPWROG-1904 7-P states that this TR documents the EJvfAsfor the North Anna Units 1 and 2 reactor vessel inlet and outlet nozzle Rotterdam welds, nozzle forgings and nozzle belt forgings (a.k. a, upper shell forgings). The P WROG indicated that these locations were chosen for their upper-shelf energy (USE) potentially falling below the 50 ft-lb limit at 80-years (72 EFPY) for subsequent license renewal.

Section 3.2, "J-IntegralResistanceModels" ofPWROG-1 9047-P provides the basic form ofJ-R model as expressed in NUREGICR-5729 and RG 1.161. Furthermore, PWROG-19047-P provides the different parameters, variables and assumed values used in the EJvfAs for North Anna, Units 1 and 2.

In particular, PWROG-1 9047-P states that for the variable CVN = Charpy V-notch Impact Energy assumed the 80-year projected USE value. RG 1.1 61 and Appendix K ofSectionXI to the ASME Code indicate that toughness properties for the corresponding flaw orientation is used in the analysis (e.g.,

toughness properties corresponding to T-L or weak orientation for circumferential flaws, or L-T or strong orientation for axial flaws).

However, the staff noted that PWROG-1 9047-P does not provide the 80-year projected USE values for the components assessed in the EJvfAs, nor does it provide a supporting basis that EJvfAs for North Anna, Units 1 and 2. In addition, the PWROG did not provide the details for the variables/assumptions used to determine these 80-year projected USE values, nor did it provide a reference to the current licensing basis document that supports these values.

NRCRequest a) Provide the 80-year projected USE values for the components assessed in the PWROG 19047-P for North Anna, Units 1 and 2, using this model.

b) Explain and justify the methodology, including the variables/assumptions (with the appropriate reference to the current licensing basis document where applicable), used to derive the 80 year projected USE values for these components. If applicable, this justification should address the selection of toughness properties for the corresponding flaw orientation in the material (e.g., T-L or weak orientation for circumferential flaws, or L-T or strong orientation for axial flaws) used in EJvfAsforNorthAnna, Units 1 and 2.

Response

(a) The 80-year USE values for North Anna Unit I and 2 are documented in WCAP-18364-NP [8],

Section 5.

(b) The 80-year USE projections, including the methodology utilized and input parameters are documented in WCAP-18364-NP [8], Section 5, which was submitted to USNRC by Dominion for the North Anna SLR application [1 2]. The methodology is consistent with that contained in Regulatory Guide 1. 99 [6]. WCAP-1 8364-NP also refers to PWROG-1 8005-NP [4] as the original source of the input parameters. These input parameters represent weak orientation material properties in all cases.

• • • This record was final approved on 11/20/2020 5:34 :16 PM. (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-16 Westinghouse Non-Proprietary Class 3 Page 10 of 13 Our ref: LTR-SDA-20-082, Rev. 0 November 19, 2020 RAIOS Issue Section 4.1. 4 of P WROG-19047-P states the procedures for the J-applied calculation for Levels CID described in K-5000 ofAppendix K to Section XI of the ASME Code are the same as those for Levels AIB described in K-4000, except that the effect of cladding/base metal differential thermal expansion needs to be considered for Levels CID per K-5210(a). Therefore, stress data from the finite element model (FEM) with cladding is included for the Levels CID evaluation. However, it is not clear to the staff how the effects of the cladding (i.e., the stress due to the different thermal expansion between cladding and base metal) was captured in the FEM.

NRCRequest a) Provide a description of how the stress due to the different thermal expansion between cladding and base metal is captured in the FEM. For example, this stress due to the thermal expansion difference should be maximum at room temperature and decreases as temperature increases.

b) Describe and justify that the FEM addresses the cladding/base metal differential thermal expansion discussed in K-5 210.

Response

(a) The FEA for Level CID explicitly modeled the cladding with appropriate material properties such as thermal expansion coefficients per AS:ME Section II. Therefore, the differential thermal expansion between the cladding and base metal is considered.

(b) The effect of the cladding/base metal differential thermal expansion is addressed by explicit modeling of the cladding in the FEA.

• • • This record was final approved on 11/20/2020 5:34 :16 PM. (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-17 Westinghouse Non-Proprietary Class 3 Page 11 of 13 Our ref: L TR-SDA-20-082, Rev. 0 November 19, 2020 RAI06 Issue Section 4. I. 7, "Temperature Range for Upper Shelf Fracture Toughness Evaluations" of PWROG-19047-P states that the transition region toughness is obtainedfrom the ASME SectionXI equation for crack initiation (i.e., Section A -4200) and using an RTNDT value of 208. 3 °F for a flaw depth of 1/10 the wall thickness. PWROG-19047-P cites page 5 of North Anna Power Station Updated Final Safety Analysis Report, Revision 55.

The staff was not able to independently confirm this Adjusted Reference Temperature value for the components in North Anna, Units I and 2, in the cited reference. In addition, it appears that the components being represented by this RTNDT value of 208. 3°F are the nozzle-to-shell welds; however, it was not specified in the PWROG-1 9047-P. The staff also noted that it is not clear how this RTNDT value is representative or bounding for the components assessed in the El'vfAs for North Anna, Units 1 and 2.

NRC Request a) Clarify the components in the El'vfAsfor North Anna, Units 1 and 2, that are being represented by the RTNDT value of208. 3 °F.

b) Provide the unirradiated reference temperature (RTNDT{uJ), sigma delta, sigma initial, jluence, chemistry factor, copper and nickel values used to calculate the ART and a reference to the applicable current licensing basis document for these values.

c) Justify that the ART value used in PWROG-1904 7-P is representative/bo1111dingfor the applicable components being evaluated in the EMAs f or North A nna Units I and 2.

Response

The reference page 5 of[S] " in Section 4 .1.7 of PWROG- 19047 is a transcription error, refers to a table in a Wes tinghouse internal analysis input summary document that is shown below. The table shows the calculation of 1/ l0T ART calculation specifically for the EMA. This valu e is applicable to the nozzle-to-shell welds and uses a bounding flu ence va lue, as discussed in the responses to RAI-02.

ART \',i h1t$ IO br 1"$f'd ,i 1 1Ju* l tlOT Flaw London In 1hr l;.:\IA Copper .'-l<ktl flu f' b('f' P1*rdlr lf'd Mes, Conlt*nt<')

Sul'r. R.T-:,."TlT(f.'.p> a,'" a/ '> AR'r')

Mntrrlnl C out rnt(l > CF"' (x 10 19 nlr-m\

Fff'l ("F)

.MlT.-,"DT(5}

(' F') (' F) (' F) F)

(\\'I_ O/*) (wt. */o) £ > 1.0;\IPV) c*FJ lnle-'1 Nozzle 10 Upper 0.3l 1.13 293.4l O.IO 0.41 30 122 .3 0 28.0 56.0 208.3 Sh,11 Wdds Outlet Nozzle to 0.35 1.1 3 29).45 0.10 0.-11; 30 111.J 0 2$.0 56.0 20$.3 1>pcr She ll Wehb Notes:

(1) Conservatively, 1he copper and nickel values shown are 1he limiting, i.e. highest, for 1he component listed in PWROG-1 8005-NP [4] between Units 1 and 2.

(2) Based on Table 1 and 2 of Regulatory Guide 1.99 [6] using the copper and nickel weight percent values.

(3) FF = fluence factor = f'.028 - 0 10" CD) per Regulatory Guide 1.99 [6].

(4) Taken from PWROG-1 8005-NP [4].

(5) Predicted i'> RTNDT = CF* FF per Regulatory Guide 1.99, Revision 2 [6].

(6) The initial RTNDT values are based on measured values; therefore cri = 0°F.

(7) Per Regulatory Guide 1. 99 [6], " " = 28°F for welds when surveillance capsule data is not used; however, " " need not exceed 0.5*ts RTNDT.

(8) Margin = 2*(crr2 + cr"')°'

(9) ART = RTNDT(UJ + i'>RTNDr + Margin per Regulatory Guide 1.99 [6].

• • • This record was final approved on 11 /20/202 0 5:34:16 PM. (This statement was added by the PRIME system upon its validation )

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-18 Westinghouse Non-Proprietary Class 3 Page 12 of 13 Our ref: LTR-SDA-20-082, Rev. 0 November 19, 2020 RAI07 Issue K-5400 of Appendix K to Section XI of the ASME Code states that when the applicable stress components vary with time during Level C or D Service Loadings, evaluation shall be performed at various times during the postulated loading to determine the limiting conditions for the flaw extension and flaw stability criteria. The J-integral resistance shall be determined at each of the times the evaluation is performed using the metal temperature associated with each flaw depth evaluated The staff noted that PWROG-1 9047-P does not explicitly discuss how the EA1Asfor North Anna, Units 1 and 2, address K-5400. It appears that K-5400 for the nozzle-to-shell welds for North Anna, Units 1 and 2, is addressed in Figure 4-4 and Figure 4-6; however, it is not clear how PWROG-1 9047-P addresses K-5400 for the upper shell forgings and nozzle forgings for North Anna, Units 1 and 2.

NRCRequest a) Clarify/confirm that Figures 4-4 and 4-6 address K -5400 for the inlet nozzle-to-shell weld and outlet nozzle-to-shell weld, respectively. If not, describe and justify how K-5400 is addressed for the nozzle-to-shell welds for NorthAnna, Units 1 and 2.

b) Describe and justify how K-5400 ofAppendix K to Section XI of the ASME Code is addressed for the upper shell forgings and nozzle forgings for North Anna, Units 1 and 2.

Response

a) J,ppli,d as a function oftime for the Level D SLB transient was calculated. The corresponding crack tip temperature for each time step was obta ined from the FEA PWROG-1 9047-P, Figures 4-4 and 4-6 plotted the J,pp1;,d as well as the Im,t,ria1 mean curve from all the transient time points vs. their corresponding crack tip temperatures for the inlet nozzle-to-shell weld and outlet nozzle-to-shell weld, respectively. Figures 4-5 and 4-7 plots the Level D J,ppl;,d along with the associated Im,tcria1 mean curve at the most limiting time points for the inlet nozzle-to-shell weld and outlet nozzle-to-shell weld, respectively. Therefore, the inlet and outlet nozzle-to-shell weld EMAs addressed K-5400 of ASME Section XI.

b) The Level D J,pp1;,d for all locations was calculated for all FEA time points for the SLB transient.

The most limiting J,pp1;,d for the entire transient is compared to the J-R at either the metal (crack tip) temperature or conservatively at 600°F . Therefore, the upper shell and nozzle forgings EMAs addressed K-5400 of ASME Section XI.

• • • This record was final approved on 11/20/2020 5:34 :16 PM. (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 FRAMATOME INC. NON-PROPRIETARY A-19 Westinghouse Non-Proprietary Class 3 Page 13 of 13 Our ref: LTR-SDA-20-082, Rev. 0 November 19, 2020 This letter was created and verified in accordance with Westinghouse Level 2 Procedures W2-8.3-101 and W2-8.4-102.

If you have any questions or require further infonnation, please contact the undersigned.

Author Name(s) Signature / Date Scope Gordon Z. Hall Electro11ically Approved* All Verifier Name(s) Signature / Date Scope Jay D. White (Lead Verifier) Electro11ically Approved* RA.Is 01 , 05 and 07 Benjamin Mays Electro11ically Approved* RA.Is 02, 04 and 06 J. Brian Hall Electro11ically Approved* RA.103 Manager Name Signature / Date Stephen P. Rigby Electro11ically Approve,l*

• Electronically approved records are authenticated in the electronic document management syst..n.

© 2020 Westinghouse Electric Company LLC A ll Rights Reserved 8westinghouse

"'This record was final approved on 11/20/2020 5 :34 :16 PM . (This statement was added by the PRIME system upon its validation)

PWROG-19047-NP-A August, 2021 Revision 0

• • • This record was final approved on 9/7/2021 12:18:35 PM. (This statement was added by the PRIME system upon its validation)