ML25163A041

Enclosure 3: Non-Proprietary Documents

ML25163A041
Person / Time
Site:	Callaway
Issue date:	06/11/2025
From:	Ameren Missouri, Union Electric Co
To:	Office of Nuclear Reactor Regulation
Shared Package
ML25163A037	List: ML25163A038 ML25163A041 ULNRC-06948, Enclosure 4: Affidavits for Proprietary Documents
References
ULNRC-06948 32-9393028-001, 51-9392748-001, 32-9392644-001
Download: ML25163A041 (1)

Text

{{#Wiki_filter:Enclosure 3 to ULNRC-06948 Non-Proprietary Documents 32-9393028-001, Callaway BMI Nozzle One-Cycle Justification Section III Analysis (55 pages) 51-9392748-001, Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs (31 pages) 32-9392644-00 1, As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35, and 57 (24 pages)

0402-01-F01 (Rev. 023, 06/20/2024) framatOme CALCULATION

SUMMARY

SHEET (CSS) Document No. 32-9393028-001 Related: Yes No Callaway BMI Nozzle One-Cycle Justification Section III Analysis Title PURPOSE AND

SUMMARY

OF RESULTS: REV 000 PURPOSE: The purpose of this calculation is to qualify the Callaway #48 Reactor Vessel Bottom Mounted Instrument Nozzle half-nozzle repair for one cycle of operation according to the ASME B&PV Code Section III requirements (Ref. [1]). REVOOI PURPOSE: The purpose of Revision 002 is to add qualification of penetration #57 in accordance with ASME B&PV Code Section III requirements (Ref. [1]), in addition to the previously qualified penetrations #48, #30, and #35. REV 000

SUMMARY

OF RESULTS: The calculation herein demonstrates the half-nozzle repair for Callaway #48 Reactor Vessel Bottom Mounted Instrument Nozzle satisfies the applicable requirements of the ASME B&PV Code (Ref. [1]) for one cycle of operation. REV 001

SUMMARY

OF RESULTS: The calculation herein demonstrates the half-nozzle repairs for Callaway #57 Reactor Vessel Bottom Mounted Instrumentation Nozzle satisfies the applicable requirements of the ASME B&PV Code (Ref. [1]) for one cycle of operation. Proprietary information in the document is identified by bold brackets (U). Export classification I us Ec: N Part 810 DEAR EccN: N/A If the computer software used herein is not the latest version per the EASI list, AP 0402-01 requires thatjustification be provided. THE DOCUMENT CONTAINS THE FOLLOWING COMPUTER CODES HAVE BEEN USED IN THIS DOCUMENT: ASSUMPTIONS THAT SHALL BE VERIFIED PRIOR TO USE CODENERSION/REV CODENERSION/REV SCIPYENV 2024.07.3 Yes lNo to ULNRC-06948 Page 1 of 55

framatome 0402-01-FO1 (Rev. 023, Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Review Method: [Design Review (Detailed Check) Alternate Calculation Does this document establish design or technical requirements? Does this document contain Customer Required Format? Signature Block Name and Title Signature and Date Role ScopelComments Cayla Mandel, CRMANDEL LP All changes made in Revision 2 6/5/2025 Engineer_II Tomas Straka, T STRAKA M All changes made in Revision 2 Advisory Engineer 6/5/2025 Jasmine Cao, MJ CAO LR All changes made in Revision 2 Advisory Engineer 6/5/2025 Rhimou Sulldi, R SULLDI A All changes made in Revision 2 Engineering Supervisor 6/5/2025 Role Definitions: P/R/A designates Preparer (P), Reviewer (R), Approver (A); LP/LR designates Lead Preparer (LP), Lead Reviewer (LR); M designates Mentor (M) PM designates Project Manager (PM) Page 2 YES YES NO NO to ULNRc-06948

framatGme 0402-01-FOl (Rev. 023, 06/20/2024) Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Professional Engineer Certification I, the undersigned, being a Certifying Engineer competent in the applicable field of design and using the Design Specification and the drawings identified in the references as a basis for design, do hereby certify that to the best of my knowledge and belief the statements made and the conclusions drawn are correct and applicable to the affected in-scope items. Printed Name: HT Harrison III June 4, 2025 Consulting Engineer Date:

Title:

Signature: Seal: Page 3 to ULNRc-06948

framatGme Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis Record of Revision Page 4 Revision PageslSections/Paragraphs Brief Description I Change Authorization Number Changed Initial Release. The proprietary version of this document is 000 All 32-9392552-000. Initial Release. The proprietary version of this document is 001 All 32-9392552-002. Pages 1 through 8 Updated CSS, Signature Block, List of Contents, List of Figures, and List of Tables to reflect Rev. 001 contents. Page 10 Updated Section 1 to reflect Rev. 001 contents. Added columns Value [in] for BMI Nozzle #57. Added row Table 4-1 Distance from Penetration to Center of RV Bottom Head. Section 6.4.2 Added t and t0 for clarity in calculation of NB-3334.1(a)(2) Added for the remaining service life at the end of the last sentence of paragraph one for clarity. Section 6.5 Added Areva/Framatome and Ref. [1 7] in sentence 4 of paragraph 2 for clarity. Section 7.1 Updated Section 7.1 to reflect Rev. 001 contents to qualify BMI Nozzle #57. Added References [17] and [18]. Updated References [2], [4], Section 8 [1 1], and [15] to new revision. Appendix A.7 Added Appendix A.7 to evaluate the new contingency detailed in References [4], [15], and [18]. Appendix B Added Appendix B to evaluate the reinforcement criteria for BMI Nozzle #57. to ULNRc-06948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis Table of Contents Professional Engineer Certification 3 Record of Revision 4 List of Acronyms 9 I Introduction 10 1.1 PurposeandScope 10

1.2 Background

10 1.3 Results 10 2 Analytical Methodology 10 3 Assumptions 11 3.1 Unverified Assumptions 1 1 3.2 Verified Assumptions 11 4 Design Inputs 11 4.1 Geometry 11 4.2 Materials 14 5 Computer Usage 14 5.1 Software 14 5.2 ComputerFiles 15 6 Calculations I 5 6.1 Primary Stress Evaluation 16 6.1.1 ASME Code Allowable Stresses 17 6.1.2 Loading 17 6.1.3 Primary Stress Intensity and Pure Shear Stress 20 6.1.4 Triaxial Stress Qualification 24 6.2 Weld Size Requirements 25 6.3 Tentative Thickness Calculation 29 6.4 ReinforcementRequirements 30 6.4.1 RemovedArea 31 6.4.2 Limits of Reinforcement 32 6.4.3 Available Reinforcement Area 34 6.5 Primary Plus Secondary Stress and Fatigue Usage Criteria 39 7 Results 40 7.1 BMI Nozzles #30, #35, and #57 40 8 References 42 I Page 5 to ULNRC-06948

frainatorrie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis A.1 [ ] 43 A.2[ I 44 A.3 Loading Comparison 45 A.4 Pressure Design 45 A.5 Socket Weld Sizing 45 A.6 Conclusion 47 A.7 Long Fitting with One-Side Coupling Fitting Guide Tube Replacement Contingency for BMI Nozzles #30, #35, #48 and #57 47 B BMlNozzle#57Reinforcement 49 B.1 Removed Area 49 B.2 Limits of Reinforcement 49 B.3 Available Reinforcement Area 51 Page 6 to ULNRc-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis List of Figure Page Figure 4-1 : Half-Nozzle Repair Drawing 13 Figure 6-1 : Location Analyzed 16 Figure 6-2: Location of External Loads 18 Figure6-3:[ I 26 Figure 6-4: Weld Repair Drawing Dimensions 27 Figure 6-5: [ ] 28 Figure 6-6: ReinforcementArea Dimensions 30 Figure 6-7: Original J-groove Weld Uphill Area 35 Figure 6-8: Original J-groove Weld Downhill Area 36 Figure 6-9: Added Area of Reinforcement Uphill 37 Figure 6-1 0: Added Area of Reinforcement Downhill 38 Figure A-I : Fillet and Socket Weld Dimension Requirements 46 Figure A-2: Socket Weld Repair Drawing 47 Figure A-3: Contingency Thimble Guide Tube Fitting 48 Figure B-I: Original J-groove Weld Uphill Area for BMI Nozzle #57 52 Figure B-2: Original J-groove Weld Downhill Area for BMI Nozzle #57 53 Figure B-3: Added Area of Reinforcement Uphill BMI Nozzle #57 54 Figure B-4: Added Area of Reinforcement Downhill BMI Nozzle #57 55 Page 7 to ULNRc-06948

frarriatonie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis List of Tables Page Table 4-1: BMI Nozzle Repair Dimensions 12 Table 4-2: Material Designations 14 Table 4-3: Material Stress Limits 14 Table 6-1 : Alloy 690 Primary Stress Limits 17 Table 6-2: External Load Summary 19 Table 6-3: Internal Pressure Summary 20 Table 6-4: Local Piping Loads Under Service Levels 20 Table 6-5: Primary Stress Qualification 23 Table 6-6: Pure Shear Stress Qualification 24 Table 6-7: Triaxial Stress Qualification 25 Table 6-8: Weld Size Requirement Results 28 TableA-1:[ ] 43 TableA-2:[ ] 44 Page 8 to ULNRc-06948

frarnatorrie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section lii Analysis List of Acronyms Acronym Definition BMI Nozzle Bottom Mounted Instrument Nozzle CSS Calculation Cover Sheet from Framatome Procedure 0402-01-FOl LOCA Loss of Coolant Accident OCJ One-Cycle Justification SSE Safe Shutdown Earthquake OBE Operating Basis Earthquake SRSS Square Root of the Sum of the Squares Page 9 to ULNRc-06948

frarriatorrie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis I Introduction I.1 Purpose and Scope The purpose of this calculation is to qualify the Callaway No. 48 Reactor Vessel Bottom Mounted Instrument (BMI) Nozzle half-nozzle repair for one cycle of operation according to the ASME B&PV Code Section Ill requirements (Ref. [1]). Unacceptable indications were also found on the Callaway BMI Nozzles #30, #35, and #57 and are to be repaired using nearly the same method and the same materials as BMI Nozzle #48. A subsequent analysis will demonstrate the acceptability ofthe repaired penetrations for operation beyond one cycle. The socket welds connecting the thimble guide tubes to the replacement nozzles and the couplings are addressed in Appendix A.

1.2 Background

During the Spring 2025 outage, a leak in the Callaway No. 48 BMI Nozzle was discovered. A half-nozzle repair is being performed per (Ref. [2]). In addition, unacceptable indications on BMI Nozzles #30, #35, and #57 were also discovered. 1.3 Results The calculation herein demonstrates the half-nozzle repair for BMI Nozzle #48 satisfies the applicable requirements of the ASME B&PV Code (Ref. [1]) for one cycle of operation. Section 7.1 and Appendix B demonstrate that the half-nozzle repairs for BMI Nozzles #30, #35, and #57 satisfy the applicable requirements of the ASME B&PV Code (Ref. [1]) for one cycle of operation. 2 Analytical Methodology Compliant with the ASME B&PV Code (Ref. [1]) the following steps will be performed to demonstrate the acceptability of the half-nozzle repair:

• Primary stress criteria will be evaluated at the new [

] and existing BMI Nozzle.

• Reinforcement requirements will be evaluated.
• Acceptability of the new [

] with respect to the ASME Code dimensional requirements will be determined. Page 10 to ULNRc-06948

frarmnatorrie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis .[ ] 3 Assumptions 3.1 Unverified Assumptions There are no unverified assumptions used in this calculation. 3.2 Verified Assumptions 4 Design Inputs 4.1 Geometry Important nominal dimensions for the repair are listed in Table 41. The repair is shown in Figure 41. Page 11 to ULNRc-06948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Table 4-1: BMI Nozzle Repair Dimensions Page 12 to ULNRC-06948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure 4-1: Half-Nozzle Repair Drawing Page 13 to ULNRc-06948

frarriatorrie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis 4.2 Materials The material designaUons for the sub components are listed in Table 42. [ I Table 4-2: Material Designations Table 43 lists the material properties for the materials used in the analysis at the [ I (Ref.[6]). [ ] material specifications come from Ref. [7]. All other Sm values come from the original construction code for the reactor vessel and bottom instrumentation tubing, Ref. [8], and Sy and Su values come from Ref. [9]. Table 4-3: Material Stress Limits 5 Computer Usage 5.1 Software The software is being used within its specified range of applicability as defined by validation and verification requirements defined in Ref. [10]. All software errors notices applicable to this software have been reviewed and found to have no effect on this document. Page 14 to uLNRc-o6948

framatGme Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis 5.2 Computer Files The computer files used in the analysis can be found in the Coldstor system in /cold/General-Access/32/ 32-9000000/32-9392552-000/official. The listina of archived comouter files is as follows: 6 Calculations Note that all dimensions in the following sections will use the worst-case dimension, accounting for tolerances stated on the design drawings, unless otherwise stated. If no tolerance is listed the nominal value is used. [ ] Page 15 File listing of /cold/GeneralAccess/32/32-9000000/32-9392 552-000/official: 00000 drwxdc tgiattino 18742 -rw-dc tgiattino 00000 drwxdc tgiattino 00000 drwxdc tgiattino 00000 drwxdc tgiattino 0 2115 0 ./docs: 0 0 May 22 2025 10:51:53 docs May 21 2025 19:30:56 dvc.yaml May 08 2025 14:55:19 notebooks May22 2025 10:45:25 shell May 08 2025 14:55:28 src 28246 -rw-dc tgiattino 07038 -rw-dc tgiattino 08723 -rw-dc tgiattino 14059 -rw-dc tgiattino 56217 -rw-dc tgiattino 651 21404891 19915 807 5959289 ./notebooks: 58272 -rw-dc tgiattino May 08 2025 14:55:20 Makefile May 22 2025 10:51:52 buildzip May 22 2025 10:51:5 1 listingtxt May 08 2025 14:55:20 makebat May 22 2025 10:51:53 sourcezip 266 ./shell: 50913 -rwxdc tgiattino 43574 -rw-dc tgiattino 00000 drwxdc tgiattino May 08 2025 14:55:19 example.ipynb 851 3126 0 ./shell/zz_cold: May 08 2025 14:55:20 docssh May 22 2025 10:51:43 prep_for_coldstorsh May 22 2025 10:45:25 zz_cold ./src: 00000 -rw-dc tgiattino 00000 drwxdc tgiattino 54644 -rwdc tgiattino 58924 -rw dc tgiattino 0 0 1101 379 ./src/_pycache_: 10865 -rw-dc tgiattino May 08 2025 14:55:20 _init_py May 08 2025 14:55:28 _pycache_ May 08 2025 14:55:20 hello_worldpy May 08 2025 14:55:20 utilspy 525 May 08 2025 14:55:2 8 utilscpython-310.pyc to uLNRc-o6948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis 6.1 Primary Stress Evaluation Per Ref. [2], a primary stress intensity evaluation is required using the criteria defined in Ref. [1]. The evaluation checks stresses on the [ ] and the BMI Nozzle due to internal pressure and external loads. Stresses at each service level are evaluated. Figure 61 describes the locations analyzed. Figure 6-1: Location Analyzed Page 16 to ULNRc-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis L 6.1.1 ASME Code Allowable Stresses Allowable stresses are calculated at the [ ] (Ref. [6]) using the limits in Ref. [1 ]. The allowable stresses for each service level are listed in Table 61. Table 6-1: Alloy 690 Primary Stress Limits Normal operating condition stresses are not considered as there are no specific limits defined per NB-3222.1, Ref. [1]. The allowable stresses for Upset (Level B) Conditions are per NB-3223, Ref. [1], respectively. The allowable stresses for emergency (Level C) Conditions are per NB-3224, Ref. [1]. The allowable stresses for Faulted (Level D) Conditions are per NB-3225 Ref. [1]. Testing limits are per NB-3226 Ref. [1]. The allowable stresses for pure shear are per NB 3227.2, Ref. [1]. 6.1.2 Loading L Page 17 to ULNRc-06948

frarnatonie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure 6-2: Location of External Loads Page 18 to ULNRc-06948

franiatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Table 6-2: External Load Summary Page 19 to ULNRC-06948

frarriatorrie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis The maximum internal pressure for each service level are taken from the transients defined in Ref. [3] and are listed in Table 63. Table 6-3: Internal Pressure Summary _The load combinations are specified in Ref. [3]. For primary stress evaluation, the load combinations are listed as follows Table 64 calculates the services loads based on the loading combinations. Seismic loads act in the positive and negative directions, but the magnitude is taken to generate the highest stress intensity. Conservatively, deadweight is considered to act in the same direction as pressure and seismic loads. Table 6-4: Local Piping Loads Under Service Levels 6.1.3 Primary Stress Intensity and Pure Shear Stress Page 20 to ULNRc-o6948

frarnatonie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Page 21 to ULNRc-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Page 22 to ULNRc-06948

frainatoriie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Table 6-5: Primary Stress Qualification Page 23 to ULNRc-06948

frarmnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Table 6-6: Pure Shear Stress Qualification 6.1.4 Triaxial Stress Qualification Page 24 to ULNRC-06948

franiatc,rne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis Table 6-7: Triaxial Stress Qualification 6.2 Weld Size Requirements L Where: Page 25 to ULNRC-06948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure 6-3: [ ] [ ] Page 26 to ULNRC-06948

frarnatorrie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure 6-4: Weld Repair Drawing Dimensions Page 27 to ULNRc-06948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis _[ Figure 6-5: [ ] Table 6-8: Weld Size Requirement Results Page 28 to ULNRc-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis 6.3 Tentative Thickness Calculation The tentative thickness calculation of the RV and nozzle are determined by the methodology specified in NB-3324 of the ASME boiler and Pressure Vessel Code (Ref. [1]). As stated in the article, except in local areas, the wall thickness of a vessel shall never be less than that obtained from the formula in NB-3324.1 for cylindrical shells and NB-3324.2 for spherical shells. F Where: F The nozzle wall thickness considering the nominal dimensions is: t0 = Ri0 [ ] The reactor vessel wall thickness considering the nominal dimensions is: tRV[ ] The nominal wall thickness is greater than the tentative thickness for both the BMI Nozzle and the RV, therefore the requirements are met. Page 29 to ULNRc-06948

frarnatorrie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis 6.4 Reinforcement Requirements Due to the area removal in the RV to accommodate the BMI Nozzle, an evaluation is required to determine the reinforcement requirements are met. The calculation for the minimum required area of reinforcement is based on the methodology listed in NB-3330 Ref. [1]. Figure 66 describes the dimensions and areas being analyzed. Figure 6-6: Reinforcement Area Dimensions Page 30 to ULNRc-o6948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis 6.4.1 Removed Area Page 31 to ULNRc-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis 6.4.2 Limits of Reinforcement Ref. [1] establishes the limits of the reinforcement area along and normal to the vessel surface. The limits of reinforcement, measured along the mid surface of the nominal wall thickness, shall meet the following:

1. One hundred percent of the required reinforcement shall be within a distance on each side of the axis of the opening equal to the greater of the following: NB-3334.1(a)(1), [

] I NB-3334.1(a)(2), Sum of radius of finished opening, thickness of nozzle t0 (conservatively equal to zero) and vessel wall t which equals:

2. In addition, two thirds of the required reinforcement shall be within a distance on each side of the axis of the opening equal to the greater of the following: NB-3334.1(b)(1):

[ ] Where: NB-3334.1(b)(2): Where: Page 32 to ULNRc-06948

frariiatonie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis Accordingly, the limit of reinforcement Lr is: L Page 33 to ULNRc-06948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis 6.4.3 Available Reinforcement Area The available area of reinforcement is shown in Figure 66 and is calculated as follows: The outside radius of the RV (R0) is: R0=R+t=[ ] The vertical distance from center of head to outside radius of the RV (H0) is: L The thickness of the RV (tr) that was not removed is: tr[ ] The area of the original flawed J-groove weld needs to be account for as area removed. Figure 67 and Figure 68 show the nominal areas of the original j-groove weld and buttering. Page 34 to ULNRc-06948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis F Figure 6-8: Original J-groove Weld Downhill Area Page 36 to ULNRC-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure 6-9: Added Area of Reinforcement Uphill Page 37 to ULNRC-06948

frarnatonie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure 6-10: Added Area of Reinforcement Downhill Page 38 to ULNRc-06948

frarnatonie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis The total area of reinforcement is: The required area of reinforcement specified in NB-3332.2 is (Correction factor F=1.0 for spherical vessels): The remaining reinforcement area is: 6.5 Primary Plus Secondary Stress and Fatigue Usage Criteria Page 39 to ULNRc-06948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis L Based on this precedent and the current analysis, the new half-nozzle repair is considered acceptable for one operating cycle. 7 Results The calculation herein demonstrates the half-nozzle repair for BMI Nozzle No. 48 satisfies the applicable requirements of the ASME B&PV Code (Ref. [1]) for one cycle of operation. The primary stress criteria are met for [ ] and existing BMI Nozzle. The tentative thickness, reinforcement requirements, and weld repair size were all demonstrated to be compliant with the Code. [ ] 7.1 BMI Nozzles #30, #35, and #57 Primary Stress Assessment: L This OCJ analysis of BMI Nozzle #48 conservatively uses the long tube external loads and the transients defined pertain to all BMI Nozzles. Therefore, the resulting primary stresses will be conservatively the same for all BMI Nozzles. Weld Size Assessment: L. Therefore, it is concluded that nozzles #30, #35, and #57 are bound by the weld size requirements of BMI Nozzle #48 and meet the applicable criteria. Reinforcement Assessment: Page 40 to ULNRc-06948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Therefore, the OCJ analysis of BMI Nozzle #48 for reinforcement requirements, as presented in Section 6.4, bounds BMI Nozzles #30 and #35. The reinforcement requirements for BMI Nozzle #57 are analyzed in Appendix B. Primary Plus Secondary Stress. and Fatigue Assessment: As discussed in Section 6.5, BMI nozzle #48 has been qualitatively justified for primary plus secondary stress and fatigue usage criteria for one operating cycle. The same qualitative justification can be made for BMI nozzles #30, #35, and #57, and a quantitative analysis of the 3Sm primary plus secondary stress check will be performed as part of the required subsequent full Section III analysis. Repairing Multiple BMI Nozzles: Therefore, it is considered acceptable for BMI Nozzles #30, #35, and #57 to be repaired along with BMI Nozzle #48 for one operating cycle and will be quantitatively assessed in the full Section III analysis. Thimble Guide Tube to Replacement Nozzle and Coupling Analysis: Therefore, the original stress analysis on the weld bounds the repair design welds for BMI Nozzles #30, #35, and #57. Conclusion for BMI Nozzle #30, #35, and #57: Based on the analysis presented in this section and Appendix B, it is considered acceptable for BMI Nozzles #30, #35, and #57 to be repaired along with BMI Nozzle #48 for one operating cycle and will be quantitatively assessed in the full Section III analysis. Page 41 to ULNRc-06948

frainatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis 8 References Page 42 to ULNRc-06948

fram atorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis A[ A.I[ ] Table A-I: [ ] Page 43 to ULNRC-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis ] TableA-2: [ ] Page 44 to ULNRc-06948

frarriatorrie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis A.3 Loading Comparison L A.4 Pressure Design To meet the requirements of NB-3641.1 the [ ] must have a minimum thickness of: The thickness of the thimble guide tube is larger than the minimum thickness, therefore the requirement is met. A.5 Socket Weld Sizing The new welds must meet the requirements of Fig. NB-4427-1, shown in Figure Ai. Page 45 to ULNRc-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure A-I: Fillet and Socket Weld Dimension Requirements Page 46 to ULNRC-06948

frarriatonie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure A-2: Socket Weld Repair Drawing A.6 Conclusion A.7 Long Fitting with One-Side Coupling Fitting Guide Tube Replacement Contingency for BMI Nozzles #30, #35, #48 and #57 I Page 47 to ULNRC-06948

frarnatorrie Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis Figure A-3: Contingency Thimble Guide Tube Fitting Page 48 to ULNRC-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis B BMI Nozzle #57 Reinforcement B.1 Removed Area F The vertical distance from center of head-to-head inside radius (Hi) for BMI Nozzle #57 is: The vertical distance from center of head to the outside radius of the required head thickness (Ht) for BMI Nozzle #57 is: Removed area due to opening (Arem) for BMI Nozzle #57 is: L B.2 Limits of Reinforcement Recall from Section 6.4.2 that the limits of reinforcement, measured along the mid surface of the nominal wall thickness, shall meet the following:

1. One hundred percent of the required reinforcement shall be within a distance on each side of the axis of the opening equal to the greater of the following: NB-3334.1(a)(1), [

] ] Page 49 to uLNRc-o6948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section Ill Analysis NB-3334.1(a)(2), Sum of radius offinished opening, thickness of nozzle t0 (conservatively equal to zero) and vessel wall which equals: E

2. In addition, two thirds of the required reinforcement shall be within a distance on each side of the axis of the opening equal to the greater of the following: NB-3334.1 (b)(1):

[ ] Where:

• R is the mean radius of head
• t is the nominal vessel wall thickness
• r is the radius of the finished opening in the corroded condition:

NB-3334.1(b)(2): Where:

• r is the radius of the finished opening in the corroded condition
• t is the nozzle thickness (conservatively equal to zero)
• t is the nominal vessel wall thickness Page 50 to ULNRc-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis B.3 Available Reinforcement Area The thickness of the RV (tr) that was not removed is: C The area of the original flawed J-groove weld needs to be account for as area removed. Figure B-I and Figure B-2 show the nominal areas of the original j-groove weld and buttering. Page 51 to ULNRc-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure B-I: Original J-groove Weld Uphill Area for BMI Nozzle #57 Page 52 to ULNRc-06948

frarnatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure B-2: Original J-groove Weld Downhill Area for BMI Nozzle #57 The nominal areas of the added material from the weld pad and j-groove weld on the uphill and downhill sides are shown in Figure B-3 and Figure B-4. Page 53 to ULNRc-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure B-3: Added Area of Reinforcement Uphill BMI Nozzle #57 Page 54 to ULNRc-06948

frarriatorne Document No. 32-9393028-001 Callaway BMI Nozzle One-Cycle Justification Section III Analysis Figure B-4: Added Area of Reinforcement Downhill BMI Nozzle #57 The total reinforced area meets the required area of reinforcement Areq, and is greater than the total area removed, therefore the reinforcement requirements are met. Page 55 to ULNRc-06948

20004-028 (03/26/2024) framatome Framatome Inc. Engineering Information Record Document No.: 51 9392748

001, Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs Export Classification US EC:

N Part 810 D EAR ECCN: N/A I to ULNRC-06948 Page 1 of 31

frarriatorrie 20004-028 (03/26/2024) Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs SafetyRelated? jYES ENO Does this document establish design or technical requirements? j YES NO Does this document contain assumptions requiring verification? YES NO Does this document contain Customer Required Format? YES NO Signature Block Name and Title Signature and Date Role ScopelComments Stacy Yoder SL YODER P All Engineer IV 6/4/2025 John Neil CI NEIL R All Engineer IV 6/4/2025 Craig Wicker CA WICKER A All Supervisory Engineer 6/4/2025 Ed Moreno EM MORENO PM Approval of customer references Project Manager 6/4/2025 Role Definitions: P/RJA designates Preparer (P), Reviewer (R), Approver (A); LP/LR designates Lead Preparer (LP), Lead Reviewer (LR); M designates Mentor (M); PM designates Project Manager (PM) I II kIDf AflAO Page 2

framatome 20004-028 (03/26/2024) Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs Record of Revision 001 PagesiSectionsi Paragraphs Changed All All Sections 1.0, 2.1, Item 2, 4.7, 5.1, and 8.0 Figure 1-4 Brief Description I Change Authorization Original release. The proprietary version of this document is 51-9392522-001. The non-proprietary version of this document is 51-9392522-002. The indication found and the repair configurations planned at nozzle #57 are similar to those found at nozzles #30 and #35. As such, #57 is added to

1. 30 and #35 where discussions of the indications or repair configurations occur in this evaluation.

Additionally, #57 is added to #30, #35, and # 48 where the concerned nozzles are discussed as a group. Section 1.0 of#48 is added to the initial purpose statement (revision 000) for clarity. The purpose ofrevision 001 is added. Discussion and process steps for [ ] added. Section 1.0 Pluralized nozzle to nozzles at the end ofparagraph 3. Figures 1-3 & 1-5 Added for [ ] Figure callouts updated as needed. Section 6.0 Material type of [ ] updated. Section 7.0 Discussion ofpertinent locations for the [ I added. Section 8.0 Discussion of [ ] added. Section 9.0 Corrected title of Reference [2] from Callaway Unit I BMI Nozzle Repair to Callaway Unit 1 BMI Nozzle No. 30, 35, and 57 Repair Revision levels ofreferences [1, 2, 3, 4] updated per addition of [ I Throughout Adjusted spacing between sentences for consistency in the document. Revision No. 000 Page 3

frarnatorne Document No. : 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs Table of Contents Page SIGNATURE BLOCK 2 RECORD OF REVISION 3 LIST OF TABLES 5 LIST OF FIGURES 6

1.0 BACKGROUND

/PURPOSE 7 2.0 ASSUMPTIONS 14 2.1 Justified Assumptions 14 2.2 Assumptions Requiring Verification 15 3.0 INDUSTRY OCCURRENCES OF EXPOSED CARBON/LOW ALLOY STEEL BASE METAL 15 4.0 CORROSION OF LOW ALLOY STEEL EXPOSED TO RCS 16 4.1 Methodology 17 4.2 General Corrosion 17 4.2.1 General Corrosion Data 18 4.2.2 Pressure Boundary Leakage (Wastage) 19 4.2.3 Long Term General Corrosion 19 4.3 Crevice Corrosion 19 4.4 Galvanic Corrosion 20 4.5 Stress Corrosion Cracking 20 4.6 Hydrogen Embrittlement 21 4.7 [ I 21 5.0 CORROSION OF ALLOY 690 AND ALLOY 52M 22 5.1 General Corrosion 22 5.2 Crevice Corrosion 22 5.3 Galvanic Corrosion 22 5.4 Low Temperature Crack Propagation 22 5.5 Stress Corrosion Cracking 23 6.0 SCC SUSCEPTIBILITY OF STAINLESS STEEL THIMBLE GUIDE TUBE [ ] 24 7.0 SCC SUSCEPTIBILITY OF STAINLESS STEEL [ ] 25

8.0 CONCLUSION

S 27

9.0 REFERENCES

28 Page 4

frarnatorrie Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs List of Tables Page Table 4-1: [ ] 18 3 to ULNRC 06948 Page 5

frarriatorne Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs List of Figures Page Figurel-1:[ ] 9 Figurel-2:[ ] 10 Figurel-3:[ ] 11 Figure 1-4:[ ] 12 Figure 1-5:[ ] 13 Page 6

frarnatorne Document No. : 51 9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs

1.0 BACKGROUND

IPURPOSE During the 2025 (R27) Mode 3 startup leak check visual inspection at Callaway, potential reactor coolant leakage was identified. The leakage was observed at Bottom Mounted Instrumentation (BMI) nozzle, Penetration #48, on the outside surface of the reactor vessel bottom head (RVBH) at the interface between the RVBH penetration and the BMI nozzle [ 1]. As part of the subsequent extent-of-condition investigation, ultrasonic testing and visual examinations were performed on all 58 BMI nozzles. Fabrication flaws were discovered in the BMI nozzle 48 J-groove weld, and unacceptable indications consistent with stress corrosion cracking (SCC) were found on the i-groove welds of BMI nozzles #30, #35, and #57. The original BMI nozzle #48 configuration, as shown in Figure 1-1 [2] consists of an Alloy 600 nozzle welded to the RVBH inside surface with Alloy 82/182 weld material [1]. Figure 1-1 is representative of the general original configuration for BMI nozzles #30, #35, and #57. It is noted that Figure 1-1 has been edited herein from Reference [2] to exclude the temporary mechanical plug and dimensions from the figure. Framatome will utilize the [ ] The process will include the following steps per References [1, 2, 3, 4, 5]: 1. [ ] 3 to ULNRC 06918 Page 7

frainatorrie Document No. : 51 -9392748-00 1 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs The repaired configurations will expose low alloy steel (LAS) base metal ofthe RVBH to borated coolant at Locations A and B, see Figure 1-2 through Figure 1-5. Location A is the [ I Location B is [ I Note, a larger [ ] Location A and Location B. The purpose of this document is to evaluate potential material degradation via corrosion for the repaired configuration ofnozzle #48. The evaluation will focus on 1) [ ] For the exposed LAS, types ofpotential material degradation that will be considered include general corrosion, crevice corrosion, galvanic corrosion, stress corrosion cracking (5CC), hydrogen embrittlement, [ ] The evaluation of the new Ni-based alloy components will focus primarily on primary water stress corrosion cracking (PWSCC) susceptibility. The focus of the evaluation of the affected stainless steel, specifically the thimble guide tube adjacent to the [ ] will be 5CC susceptibility. The purpose ofrevision 001 is to include the repaired configuration ofnozzle #57 and include the [ ] repair configurations in the evaluation performed herein. This evaluation does not address the [ ] or the existing Alloy 82/182 ID J-groove welds and buttering as they do not form a part of the pressure boundary following the repairs. The corrosion evaluation will consider mechanisms applicable to the Callaway BMI nozzles #30, #35, #48, and

1. 57 in the repaired configurations for the life of the repairs, defined as the remainder of the 60-year licensed operational life of the plant, through 2044. The calculated general corrosion rate of the exposed LAS is applicable aslongas[

] Page 8

frarnatorne Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs Figure 1-1: [ ] Page 9

frarriatorne Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs Figure 1-2: [ ] 3 to ULNRC 06918 Page 10

frarnatorne Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs Figure 1-3: [ ] Page 11

frarnatorne Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs Figure 1-4: [ I 3 to ULNRC 06948 Page 12

frarnatorne Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs Figure 1-5: [ ] Page 13

frarnatorrie Document No. : 51 -9392748-00 1 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs 2.0 ASSUMPTIONS 2.1 Justified Assumptions 1. The calculated combined corrosion rate in Section 4.2. 1 is based on [ ] corrosion rates assigned for each ofthree plant conditions: operation, shutdown, and startup. For a cycle length of [ ] are spent in each of these modes, respectively. [ ] the impact on the calculated corrosion rates is considered [ ] NOTE: The combined corrosion rate remains applicable for a [ I 2. It is assumed that Callaway will maintain RCS primary water chemistry in accordance with EPRI PWR Primary Water Chemistry Guidelines during the life ofthe repairs. Continued validation of this assumption is performed through water chemistry program monitoring per the License Renewal Application [6, 7]. The utility has confirmed adherence to Revision 7 of the guidelines [8]. Off-chemistry excursions could impact the LAS general corrosion rate calculated herein and/or conclusions for other degradation mechanisms. This assumption supports the application of the experimental corrosion rates established in Section 4.2.1 to the repaired configurations for the Callaway BMI nozzles #30, #35, #48, and #57. [ ] 3. The calculated LAS corrosion rate in Section 4.2.1 is assumed to be conservative, based on the following: a. [ I 3 to ULNRC 06948 Page 14

frarnatorne Document No. : 51 -9392748-00 1 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs C. [ I The above positions justify the assumption of conservatism; the actual LAS general corrosion rate is expected to be bounded by that calculated in Section 4.2. 1. 2.2 Assumptions Requiring Verification There are no assumptions requiring verification. 3.0 INDUSTRY OCCURRENCES OF EXPOSED CARBONILOW ALLOY STEEL BASE METAL The carbon or LAS components in the pressurizer, reactor vessel (RV), and the steam generator (SG) exposed to PWR RCS primary coolant are clad with either stainless steel or Ni-based alloy in order to prevent corrosion of the carbon or LAS base metal. Throughout the operating history of domestic PWRs, there have been many cases where a localized area ofthe carbon or LAS base metal has been exposed to the PWR RCS primary coolant due to damage to the cladding or a repair configuration. Several such instances are listed below: 1 960s Yankee-Rowe RV Surveillance capsules fell from holder assemblies to the bottom of the vessel, releasing test specimens and other debris, leading to perforations in the cladding. 1990 Three Mile Island Unit 1 (TMI-1) SG Several tubes were separated within the tubesheet due to 5CC and repaired via explosive expansion. The repair exposed a small area in the tubesheet penetrations to primary coolant. (LER 289-1990-005) 1 990 Arkansas Nuclear One Unit 1 pressurizer A leak was detected at the pressurizer upper level tap nozzle within the steam space in December 1990. The repair consisted ofremoving the outer section of the nozzle followed by welding a new section of nozzle to the OD of the pressurizer. An axial crevice exists between the old and new nozzle sections, which exposes the pressurizer shell base metal to primary coolant. UT examinations from the pressurizer OD have revealed no indications of significant corrosion. (LER 3 13-1990-02 1) 1991 Oconee Unit 1 SG A mis-drilled tube-sheet hole in the upper tube-sheet ofone ofthe SGs, during plugging operation in 199 1, led to exposure of a small area of unclad tube-sheet to primary coolant. [Note: This area ofthe tube-sheet has since been patched and is no longer exposed to coolant.] 1993 McGuire Unit 2 RV A defect in the vessel cladding was discovered during an inspection in July 1 993 ; the defect is believed to have occurred as a result of a pipe dropped in the vessel during construction (1975). 1993 San Onofre Nuclear Generating Station Unit 2 hot leg nozzle A repair to a hot leg nozzle was completed during the 1993 outage at the SONGS Unit 2. This repair consisted ofreplacing a section ofthe existing Alloy 600 nozzle with a new nozzle section fabrication from Alloy 690. A gap approximately [ ] wide exists between the two nozzle sections where the carbon steel base metal is exposed to the primary coolant. Verbal communication with SONGS personnel indicated that the hot leg nozzle containing this repair was removed and the exposed carbon steel examined. 1994 Calvert Cliffs Unit 1 pressurizer Two leaking heater nozzles in the lower head of the pressurizer were partially removed and the penetrations were plugged in 1994. (LER 3 17-1994-003) 3 to ULNRC 06948 Page 15

frarnatorne Document No. : 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs 1997 Oconee Unit 1 Once Through Steam Generator (OTSG) manway During the end-of-cycle (EOC) 17 refueling outage, a degraded area was observed in the bore ofthe lB OTSG. Subsequent inspection revealed a [ ] circumferential damaged area to the cladding surface ofthe manway opening. The exposure ofthe base metal was confirmed by etching. 2001 Control Rod Drive Mechanism (CRDM) repairs at Oconee Unit 2, Oconee Unit 3, Crystal River Unit 3, Three Mile Island Unit 1, and Surry Unit 1. (LER 270-2001-002, 287-2001-003, 302-2001-004, 289-2001-002, 280-2001-003) 2002 CRDM repairs at Oconee Unit 1 and Oconee Unit 2. (LER 269-2002-003, 270-2002-002) 2003 CRDM/Control Element Drive Mechanism (CEDM) repairs at St. Lucie Unit 2 and Millstone Unit 2, halfnozzle repairs of South Texas Project Unit 1 bottom mounted instrument nozzles, half nozzle repairs ofpressurizer instrument nozzles at Crystal River Unit 3. (LER 389-2003-002, 498-2003-003, 302-2003-003) 2005 Half-nozzle modification for the TMI-1 pressurizer vent nozzle. 20 13 Half-nozzle repair on RV bottom mounted instrument nozzle to the Palo Verde Unit 3. (LER 2013-001-00) 2013 Framatome Inside Diameter Temper Bead (IDTB) half-nozzle repairs to the Harris CRDM nozzle penetrations. (LER 400-2013-001) 20 1 7 Half-nozzle repair on RV head instrument nozzle after a leak was identified at Limerick Generating Station, Unit 2. (LER 2017-004-01) 20 1 7 Catawba Unit 2, SG D hot leg channel head visual inspection identified an area of missing and/or thin cladding [10]. 2020 Half-nozzle repair on RV instrument nozzle after a leak was identified at Peach Bottom Atomic Power Station Unit 2. (LER 2020-002-00) 2023 Nozzle repair on PZR thermowell after a boric acid leak was identified at PVNGS Unit 1. (LER 50- 528/2023-002-00) In most ofthese instances, carbon or LAS base metal was exposed to primary coolant in a localized area. Each plant returned to normal operation with the base metal exposed. Although some components were eventually replaced, the Yankee-Rowe vessel operated for approximately 30 years with the base metal exposed. 4.0 CORROSION OF LOW ALLOY STEEL EXPOSED TO RCS Several types of corrosion can occur when carbon steel and LAS base metal are exposed to primary coolant. [ ] The following sections discuss the possible corrosion mechanisms for the exposed LAS base metal at the repair Locations A and B, as depicted in Figure 1-2 through Figure 1-5. Page 16

frarnatorne Document No. : 51 -9392748-00 1 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs 4.1 Methodology The Framatome methodology used to evaluate the potential for corrosion ofthe exposed LAS due to these repairs is as follows: Wastage I General Corrosion ] Crevice Corrosion I Galvanic Corrosion I Stress Corrosion Cracking I Hydrogen Embrittlement I [ I 4.2 General Corrosion General corrosion is defined as uniform deterioration of a surface by chemical or electrochemical reactions with the environment. Austenitic stainless steels and Ni-based alloys (e.g. wrought Type 304, Type 316, Alloy 600, and Alloy 690 materials and their equivalent weld metals) are virtually immune to general corrosion from exposure to PWR primary coolant. Carbon steel and LASs, however, may be subject to general corrosion upon exposure to primary coolant. The general corrosion rates of carbon steel and LASs during aerated and deaerated reactor coolant conditions are discussed below. ULNRC-06918 Page 17

Controlled Dn frarnatorne Document No. : 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs 4.2.1 General Corrosion Data Many studies [12, 1 3, 14, 1 5, 16, 1 7, 1 8, 1 9, 20, 2 1] have reported corrosion rates of carbon steel and LASs in high temperature water. In many studies, the corrosion rates for carbon steel and LASs have been observed to be similar; the corrosion data [13, 14, 17, 20, 21] includes carbon steel and LASs such as ASME SA-212 and SA-302 Grade B. The material ofthe Callaway RVBH [ ] is essentially equivalent to SA-302 Grade B, except that [ ] also includes some nickel. Nickel has no deleterious effect on the general corrosion ofLAS, so the referenced corrosiondata is considered applicable to the Callaway RVBH. The Electric Power Research Institute (EPRI) has also compiled a handbook [22] on boric acid corrosion (BAC). This handbook summarizes the industry field experience with BAC incidents, contains a discussion ofBAC mechanisms, and contains a compilation ofprior BAC testing and results. One evaluation was completed in response to the Yankee-Rowe incident (noted in Section 3.0); in the evaluation, A-212 carbon steel was exposed to primary coolant in aerated and deaerated conditions [23]. It was shown that under deaerated conditions (i.e., during operation), the corrosion rate depended on temperature, fluid velocity, boric acid concentration, and time. At the maximum velocity tested (36 ft/sec.), the corrosion rate was determined to be 0.003 ipy the maximum corrosion rate reported [23]. Under low flow or stagnant conditions at 650°F, a maximum corrosion rate of 0.0009 ipy was reported. In the same study under shutdown conditions (aerated, low temperature [-70°F]), the maximum corrosion rate was determined to be 0.0015 inch for a two-month shutdown, or 0.009 ipy [23]. The slow corrosion rates from this test data are consistent with the operating experience of LAS exposed to PWR primary coolant (partial list provided in Section 3.0) in that no issues have been reported regarding these locations. [ I Table 4-1: [ I Page 18

Controlled Documer frarriatorne Document No. : 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs 4.2.2 Pressure Boundary Leakage (Wastage) For the primary coolant inside the repaired BMI nozzle penetrations, there is no mechanism for boric acid to concentrate due to the new pressure boundary material removing the leak path. [ I As indicated in Section 4.2. 1, test data of LAS exposed to borated water similar to primary coolant shows very slow corrosion rates relative to wastage, which can be greater than one inchlyear [22]. [ ] It is noted a pressure boundary leak was discovered at BMI nozzle #48 during the 2025 (R27) Mode 3 startup leak check visual inspection at Callaway, but absence of this leak previously supports the argument that wastage has not already occurred. Since this evaluation is only concerned with LAS corrosion exposed to the primary coolant, [ 4.2.3 Long Term General Corrosion [ ] 4.3 Crevice Corrosion The environmental conditions in a crevice can become aggressive with time and can cause accelerated local corrosion. Experiments were conducted to study crevice corrosion of LAS in primary coolant. The results showed no evidence of increased corrosion in the crevices for both aerated and deaerated conditions (i.e., crevice corrosion could not be distinguished from general corrosion) [17, 23]. [ I Page 19

frarnatorne Document No. : 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs [ I 4.4 Galvanic Corrosion Galvanic corrosion may occur when two dissimilar metals in contact are exposed to a conductive solution. The larger the electrochemical potential difference between the two metals, the greater the likelihood of galvanic corrosion. Low alloy steel is more anodic than Ni-based weld metals (Alloy 52M) and could therefore be subject to galvanic attack when coupled and exposed to reactor coolant, as in the repaired configurations. Several corrosion tests were performed to determine the influence of coupling between low alloy and austenitic stainless steel, which has approximately the same corrosion potential as Ni-based alloys. In one test, LASs were coupled (i.e., welded) to stainless steels exposed to high purity water for 1000 hours at 546°F in steam, steam/water, saturated water, and sub-cooled water in aerated and deaerated conditions [121. The coupled specimen did not exhibit any accelerated rates ofcorrosion. Specimens made from 5% chromium steel coupled to Type 304 stainless steel were exposed to aerated water at 500°F for 85 days (-2000 hours) and 98 days (2300 hours) with no evidence ofgalvanic corrosion [21]. In each ofthe tests described above, corrosion rates were not affected by coupling. The results of the NRC s boric acid corrosion test program at Argonne National Laboratory have shown that the galvanic difference between ASTM A533 Grade B LAS, Alloy 600, and Type 308 stainless steel (used in reactor vessel cladding) is not significant enough to consider galvanic corrosion as a strong contributor to the overall BAC process [25]. [ I 4.5 Stress Corrosion Cracking Stress corrosion cracking (5CC) can occur only when the following three conditions are present: 1 ) a susceptible material, 2) a tensile stress, and 3) an aggressive environment. Numerous laboratory studies have been performed on carbon steel and LASs to assess their susceptibility to 5CC in various aqueous environments. Most of these studies, which have been performed on reactor materials in light water reactor (LWR) environments, have been coordinated under the auspices of the International Cyclic Crack Growth Rate (ICCGR) Group. While this group has focused its attention on corrosion fatigue, much of the work over the past two decades has also been on SCC. A review of the work conducted through 1990 appears in a paper by Scott and Tice [26]. A more recent review of the relevant laboratory work and field experience appears in a report prepared for the CE Owners Group [27]. The conclusions of both evaluations are the same, Page 20

frarnatorrie Document No. : 51 -9392748-00 1 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs i.e., considering the environmental conditions present in a PWR, low alloy and carbon steel will not be subject to scc unless they experience some prolonged departure from expected normal operation conditions, which is not permitted by the water chemistry guidelines. The results of these evaluations have been supported by several subsequent laboratory studies [28, 29, 30, 31]. Extensive PWR (see Section 3.0) and boiling water reactor (BWR) [3 1] operating experience related to LAS being exposed to reactor coolant has not resulted in OE for SCC of LAS reactor pressure vessel material to any significant depth. Noteworthy are 5CC cracks revealed in the stainless steel cladding in charging pumps [32, 33]. The interdendritic cracks, present in the cladding, were determined to have blunted at the clad/LAS interface. [ ] 4.6 Hydrogen Embrittlement Hydrogen embrittlement in LASs results from excessive amounts of hydrogen in a metals crystal lattice. This type of damage is a mechanical/environmental failure process, which usually occurs in combination with residual or applied stresses. Hydrogen embrittlement is observed most often in plastically deformed metals or alloys in high pressure hydrogen environments and is characterized by ductility losses and lowering ofthe fracture toughness. High pressure hydrogen environments are not typical of PWR systems and are defined as an environment with approximately 5,000-10,000 psi [34]. Hydrogen exists within the reactor coolant system (used as an oxygen scavenger) and is expected to accumulate at locations such as the top of the pressurizer. Hydrogen-induced mechanical property changes are more pronounced in high-strength low-toughness steels. Low-strength high-toughness steels such as SA-212, SA-302, or SA-533 are little affected by hydrogen in this manner [12]. In the case of a PWR RV under normal operation, the corrosion rate and diffusion rate of hydrogen through the vessel wall are such that the maximum hydrogen concentration in the steel of the lower head is approximately 0.3 parts per million (ppm) [12]. In either case, the quantity of hydrogen that may accumulate at locations within the coolant system is not expected to induce hydrogen embrittlement in materials at those locations. [ ] 4.7 [ ] [ ] Page 21

frarnatorne Document No. : 51 -9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs [ I 5.0 CORROSION OF ALLOY 690 AND ALLOY 52M The following subsections discuss the potential corrosion mechanisms for the Alloy 690 [ ] shown in Figure 1-2 through Figure 1-5. 5.1 General Corrosion General corrosion is defined as uniform deterioration of a surface by chemical or electrochemical reactions with the environment. Ni-based alloys (e.g., Alloy 600, Alloy 690, and their equivalent weld metals) are utilized in PWR and BWR systems because they are essentially immune to general corrosion due to the formation of a passivating film ofvarious iron, nickel, and chromium oxides [36]. The potentially aerated environment in the RCS during shutdown will be more akin to a BWR environment. To date, there have been no reported instances of issues arising from general corrosion of Alloy 690 in BWR environments, so general corrosion is not expected to be a concern for this alloy for the life ofthe BMI nozzles #30, #35, #48, and #57 modifications. [ I 5.2 Crevice Corrosion The proposed repairs to the BMI nozzles will create crevice conditions (high aspect ratio) associated with the Alloy 690 nozzle (Location B). However, these Ni-based alloys in general have excellent resistance to general and crevice corrosion under typical PWR conditions [38, 39]. [ I 5.3 Galvanic Corrosion Galvanic corrosion may occur when two different metals in contact are exposed to a conductive solution. As discussed in Section 4.4, galvanic corrosion between LAS and Alloy 690 or [ I 5.4 Low Temperature Crack Propagation Low temperature crack propagation (LTCP) occurs in Ni-based alloys and is considered a form of hydrogen embrittlement. This type of damage is characterized by a reduction in fracture toughness when exposed to water (particularly hydrogenated) at low temperatures (below 150°C (302°F)). This phenomenon starts from pre existing sharp cracks, with hydrogen at grain boundaries, and at stress intensity levels greater than a critical value. While RCS temperatures in the shutdown and startup conditions are low enough to induce LTCP in very high pressure hydrogen environments, such environments are not typical of PWR systems [40]. [ I Page 22

frarnatorne Document No. : 51 -9392748-00 1 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs 5.5 Stress Corrosion Cracking Alloy 52M is a modified version ofAlloy 52 for improved weldability, but this variation is similar to Alloy 52 in terms ofthe PWSCC resistance properties discussed below [41]. The corrosion resistance ofAlloy 690 and weld metal Alloys 52 and 152 has been extensively studied as a result ofnumerous PWSCC failures in mill annealed Alloy 600 and weld metals Alloys 82 and 1 82 in primary water environments. As a result of Alloy 600 and Alloys 82 and 182 failures, Alloy 690 and Alloys 52/152 have been chosen by the nuclear power industry as the replacement material of choice for Alloy 600 and Alloy 82/1 82 components and welds in PWRs. A comprehensive review oftesting for the use ofAlloy 690 and Alloy 52 in PWRs cites numerous investigations and test results under a wide array of conditions, including both primary (high temperature de-oxygenated water) and secondary coolant environments [42]. The first Alloy 690 SG went on-line in May 1989 with no reported failures oftubes due to environmental degradation as of an August 1997 literature review [43]. At the time of this evaluation, there are no known reports ofAlloy 690 in-service PWSCC failures. The typical test conditions cited in the Alloy 690 literature review included temperatures up to 365°C (689°F), dissolved oxygen levels < 20 parts per billion (ppb), in doped and undoped 400°C (752°F) steam, lithium concentrations up to 20 ppm, chlorides up to 300 ppb, and various heat treatments ofAlloy 690. Reverse U-bend SCC tests within the above matrix of environmental conditions produced no PWSCC in Alloy 690. No cracking was observed in high purity water containing 16 ppm oxygen at 288°C (550°F), even in a crevice situation. Only slight intergranular cracking of Alloy 690MA (mill annealed) was observed in slow strain rate testing (SSRT) in 360°C (680°F) high purity deaerated hydrogenated water. However, the same cracking was also observed in tests under argon, so the cracking observed in high purity deaerated hydrogenated water could not be confirmed to be PWSCC [43]. The SCC resistance of weld metals Alloy 52 and 1 52 was identified as unaffected by a variety of test conditions, including primary water. No cracking occurred in weld metals containing > 22% chromium [43]. Constant extension rate test (CERT) data is available for specimens fabricated from weld mockups made from Alloys 690, Alloy 52, Alloy 152, and Alloy 82 and tested under normal and faulted (addition of 1 50 ppb chloride) primary water conditions. The water chemistry was typical primary water: 2.2 ppm Li, 1000 ppm B, 6.5 pH, > 20 cc/kg hydrogen. Neither the weld mockups nor the CERT specimens were stress relieved after the Alloy 1 52 weld prior to testing. The test temperature was 343°C (650°F), with tests performed at a constant strain rate ofeither 1x106 or 5x 1 08 sec. No evidence of SCC failures was observed on any specimens tested at the faster strain rates, only dimpled rupture fracture surfaces indicating ductile failure were reported. The results of the slower strain rate (108 sec) tests did show evidence ofSCC failure in the Alloy 82 weld metal, but not in Alloy 690 or Alloy 152. These tests demonstrate the high SCC resistance of Alloy 690 and Alloy 152 weld metal under the conditions of high stress, which include residual stresses from welding, machining, and high plastic straining of the test specimens [44]. Stress corrosion cracking test data comparing results between Alloy 690 and Alloy 600 is available in both aerated and deaerated high temperature water. Test specimens were made from a creviced double U-bend geometry and were tested for 48 weeks at 3 16°C (601 °F). Various Alloy 690 material conditions were tested, including MA, MA + thermal treatment (TT), MA followed by solution annealing (SA), cold working (cold rolled 40%), and gas tungsten arc welding (GTAW) welded specimens with matching filler metal. In tests with an environment of a minimum of 6 ppm dissolved oxygen and pH of 10, the control alloys, including Alloy 600 and Alloy 800 readily cracked, whereas Alloy 690 showed no cracking. Additional tests were carried out under deaerated conditions ( 20 ppb 02) where Alloy 690 showed no cracking, while Alloy 600 in the MA + cold roll heat treated condition cracked. Consistent with other investigators previously cited, Alloy 690TT showed a resistance to cracking. Additional tests were carried out at 360°C (680°F) in deaerated water with a pH of 10 as part of the same study. Alloy 690 material test conditions included SA (10 10°C [1850°F] and 1120°C [2048°F]) and SA+TT (1120°C [2048°F]) + TT (675°C [1247°F]). Again, no cracking of Alloy 690 was reported [45]. -O6918 Page 23

frarnatorne Document No. : 51 -9392748-00 1 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs Some studies have indicated that Alloy 690 5CC crack growth rates (CGRs) can increase dramatically if extensive cold work (especially non-uniform cold work, such as unidirectional rolling) is present [46, 47]. Extensive cold work is not thought to generally be representative ofplant components [47], and [

i Based on these studies examining the PWSCC ofAlloy 690 and Alloy 52M weld metal, it can be concluded that these alloys have a low susceptibility to PWSCC. It is expected that the Alloy 690 nozzle and [

] in this modification will have superior PWSCC performance to the existing Alloy 600 nozzle and Alloy 82/1 82 weld material. [ I 6.0 SCC SUSCEPTIBILITY OF STAINLESS STEEL THIMBLE GUIDE TUBE [ ] Stress corrosion cracking requires three synergistic elements to occur: 1 ) sustained tensile stress, 2) an aggressive (corrosive) environment and 3) a susceptible material. In the case of austenitic stainless steel in a reactor environment, aerated water is considered an aggressive environment. Austenitic stainless steels are generally susceptible to SCC in elevated temperature environments where impurities such as halogens (e.g., chlorides and fluorides) and/or dissolved oxygen are present or when significantly cold worked. Cracking can occur as intergranular stress corrosion cracking (IGSCC) or transgranular stress corrosion cracking (TGSCC) under these conditions. Original Configuration [ I Repaired Configurations As shown in Figure 1-2 and Figure 1-4, the repair to BMI nozzle penetrations will include an [ I JLNRC 06948 Page 24

frarnatorne Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs 1. [ ] Based on industry experience, [ ] This mechanism is not considered environmental degradation and, therefore, is outside the scope of this evaluation. 7.0 SCC SUSCEPTIBILITY OF STAINLESS STEEL [ ] As shown in Figure 1-2 and Figure 1-4, the original thimble guide tube segment (SA-2 13 TP3O4L) [ ] to ULNRC 06948 Page 25

frarnatorne Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs The location of the [ ] [ I Page 26

frarnatorrie Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs

8.0 CONCLUSION

S The information presented above describes the potential corrosion mechanisms that may affect the Callaway BMI nozzle penetrations #30, #35, #48, and #57 in the repaired configurations [ ] for the life of the repairs, defined as the remainder of the 60-year licensed operational life of the plant, through 2044. [ ] [ ] Page 27

frainatorne Document No. : 51 -9392748-00 1 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs 17. Vreeland, D. C., Corrosion ofCarbon Steel and Low Alloy Steels in Primary Systems of Water-Cooled Nuclear Reactors, Presented at Netherlands-Norwegian Reactor School, Kjeller, Norway, August 1963. 18. Pearl, W. L. and Wozadlo, G. P., Corrosion ofCarbon Steel in Simulated Boiling Water and Superheated Reactor Environments, Corrosion, v21, August 1965, p. 260. 1 9. DePaul, E. J., Corrosion and Wear Handbook for Water-Cooled Reactors, McGraw-Hill Book Company, Inc. 1957. 20. Tackett, D. E. et. al., Review of Carbon Steel Corrosion Data in High-Temperature Water, High-Purity Water in Dynamic Systems, USAEC Report, WAPD-LSR(C)-134, Westinghouse Electric Corporation, October 14, 1955. 2 1. Ruther, W. E. and Hart, R. K., Influence of Oxygen on High Temperature Aqueous Corrosion of Iron, Corrosion, v19, April 1963, p. 127. 22.

• Materials Reliability Program, Boric Acid Corrosion Guidebook, Revision 2: Managing Boric Acid Corrosion Issues at PWR Power Stations (MRP-058 Rev 2), EPRI, Palo Alto, CA: 2012. 1025145.

23. Evaluation ofYankee Vessel Cladding Penetrations, Yankee Atomic Electric Company to the U. S. Atomic Energy Commission, WCAP-2855, License No. DPR-3, Docket No. 50-29, October 15, 1965. 24. [ I 25. NUREG-1823, U.S. Plant Experience With Alloy 600 Cracking and Boric Acid Corrosion of Light-Water Reactor Pressure Vessel Materials, March 2005. 26. P.M. Scott and D.R. Tice, Stress Corrosion in Low Alloy Steels, Nuclear Engineering and Design, Volume 119, 1990. 27. J.F. Hall, Low-Alloy Steel Component Corrosion Analysis Supporting Small-Diameter Alloy 600/690 Nozzle Repair/Replacement Programs, CE NPSD-1 198-NP, Revision 00, February 1 5, 2001, Non-Proprietary version available for viewing on the NRC website (ML010540212). 28. M. Herbst, et al., Effect ofChloride on Environmentally Assisted Cracking ofLow Alloy Steels in Oxygenated High Temperature Water General Corrosion, 1 5th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors. 29. T. Kubo, et al., 5CC Retardation and Propagation Behavior in Dissimilar Weldment of Alloy 1 82 and Low Alloy Steel, 1 4th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors. 30. A. Roth, et al., The Effect ofTransients on the Crack Growth Behavior ofLow Alloy Steels for Pressure Boundary Components under Light Water Reactor Operating Conditions, 1 2th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors. 3 1. H. Abe, et al., Stress Corrosion Cracking Behavior Near the Fusion Boundary of Dissimilar Weld Joint with Alloy 1 82-A533B Low Alloy Steel, 1 5th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors. 32. Information Notice No. 80-3 8, Cracking in Charging Pump Casing Cladding, Nuclear Regulatory Commission, October 31, 1980. 33. Information Notice No. 94-63, Boric Acid Corrosion of Charging Pump Casing Cause by Cladding Cracks, Nuclear Regulatory Commission, August 30, 1994. 34. Gray, H.H., Hydrogen Embrittlement Testing (STP 543), Opening Remarks, 1974. ASTM. Page 29

frarnatorrie Document No. : 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs 35. [ I 36. Wang, Y., Song, S., Wang, J., Behnamian, Y., Xu, L., Fan, H., and Xia, D.H., Correlation between Passivity Breakdown and Composition ofPassive Film Formed on Alloy 690 Studied by Sputtering XPS and FIB-HRTEM, J. Electrochem. Soc., Vol. 166, 2019. 37. [ I 38. Crum, J.R., and Nagashima, T., Review ofAlloy 690 Steam Generator Studies, Eighth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems Water Reactors, August 1997, Amelia Island, Florida, ANS. 39. Saito, N., Crevice Corrosion ofAustenitic Alloys in High-Temperature Water, Corrosion, Vol 54(9), p. 700, September 1998. 40. Demma, A., Mcllree, A., and Herrera, M., Low Temperature Crack Propagation Evaluation in Pressurized Water Reactor Service, 1 2th International Conference on Environmental Degradation of Materials in Nuclear Power Systems Water Reactors, 2005. 41. R. Zhang, et a!., New 30% Chromium-containing Ni-Cr-Fe Welding Product Provides Outstanding Resistance to PWSCC, Ductility Dip Cracking (DDC) and Meets All Other Nuclear Welding Requirements, C2012-0001743, NACE International, Corrosion 2012 Conference and Expo, Salt Lake City, UT. 42. Materials Reliability Program, Resistance to Primary Water Stress Corrosion Cracking ofAlloys 690, 52, and 152 in Pressurized Water Reactors (MRP-111), EPRI, Palo Alto, CA: 2004. 1009801. 43. Crum, J.R., Nagashima, T., Review ofAlloy 690 Steam Generator Studies, Eighth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems Water Reactors, Aug. 10-14, 1997. Amelia Island, FL, ANS. 44. Psaila-Dombrowski, M.J., et al., Evaluation ofWeld Metals 82, 152, 52, and Alloy 690 Stress Corrosion Cracking and Corrosion Fatigue Susceptibility, Eighth International Symposium on Environmental Degradation ofMaterials in Nuclear Power Systems Water Reactors, Aug. 10-14, 1997. Amelia Island, FL, ANS. 45. Sedriks, A.J., Schultz, J.W., Cordovi, M.A., Inconel Alloy 690 A New Corrosion Resistant Material, Boshoku Gijutsu, Japan Society ofCorrosion Engineering, V28(2), 1979. 46. Materials Reliability Program: Resistance to Primary Water Stress Corrosion Cracking of Alloy 690 in Pressurized Water Reactors (MRP-258). EPRI, Palo Alto, CA: 2009. 1019086. 47. Materials Reliability Program: Recommended Factors of Improvement for Evaluating Primary Water Stress Corrosion Cracking (PWSCC) Growth Rates of Thick-Wall Alloy 690 Materials and Alloy 52, 152, and Variants Welds (MRP-386). EPRI, Palo Alto, CA: 2017. 3002010756. 48. [ I 49. [ I 50. [ I Page 30

frarnatorne Document No.: 51-9392748-001 Corrosion Evaluation for Callaway Reactor Vessel Bottom Mounted Instrument Nozzle Repairs 51. [ ] 52. Palo Verde Relief Request 52 Proposed Alternative in Accordance with 10 CFR 50.55a(a)(3)(i),, Corrosion Evaluation for Palo Verde Unit 3 Reactor Vessel BMI Nozzle Modification, April 18, 2014. Accession No. ML14149A342. Page 31

0402-Ol-FOl (Rev. 023, 06/20/2024) framatome CALCULATION

SUMMARY

SHEET (CSS) Document No. 32 9392644 001 Safety Related: iYes D No Title Callaway Unit I RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 PURPOSE AND

SUMMARY

OF RESULTS: PURPOSE: During the Spring 2025 outage (R27) at Callaway Unit I , the Reactor Vessel Bottom Head (RVBH) Bottom Mounted Instrumentation (BMI) Nozzle No. 48 is being repaired due to reactor coolant leakage at the interface between the RVBH and BMI nozzle. Additionally, indications were found in the J-groove welds at the BMI Nozzles No. 30, 35, and 57 locations. The purpose of this evaluation is to perform a fracture mechanics one cycle justification (OCJ) to assess the suitability of leaving the original, as-left J-groove weld (ALJGW) in the RVBH. This assessment considers a postulated radial corner flaw extending beyond the butter-to-RVBH interface to include the transition from tensile to compressive weld residual stresses. Flaw growth is then considered for one cycle beyond the repair in 2025. An existing flaw assessment for a similar location in another plant with comparable design and loading conditions is used to qualitatively justify that the postulated flaw is acceptable for one cycle beyond the repair. In addition, a limit load analysis is done to satisfy the requirements of Article IWB-361 0(d)(2). This analysis demonstrates that the primary stress limits of Article NB-3000 are met, assuming a local area reduction of the pressure-retaining membrane that is equal to the area of the projected flaw. Since this analysis is not included in the existing ALJGW flaw evaluation, it provides the necessary validation for the repair and continued operation of the RVBH. Rev. 001 : Provide justification that the analysis in Rev. 000 is applicable to the modification of Nozzles 48, 30 and 35. Rev. 002: Provide justification that the analysis in Rev. 000 is applicable to the modification of Nozzles 48, 30, 35 and 57.

SUMMARY

OF RESULTS: Based on the comparative analysis between Callaway and an existing RVBH BMI nozzle repair ALJGW evaluation for a similar plant documented in Reference [3], it is demonstrated that the 2019 ASME B&PV Code, Section Xl, IWB-3612 requirements are met for one fuel cycle (18 months) beyond the repair in 2025. To satisfy the requirements ofArticle IWB-3610(d)(2), the primary stress requirements ofthe 2015 ASME B&PV Code, Section III, Article NB-3000 are met by limit analysis. This evaluation considers a local area reduction of the pressure retaining membrane of the nozzle opening that includes the area of the ALJGW and flaw growth for one cycle. Rev. 001: The evaluation in Rev. 000 is applicable to modification of BMI Nozzles 48, 30 and 35. Rev. 002: The evaluation in Rev. 000 is applicable to modification of BMI Nozzles 48, 30, 35 and 57. Proprietary information in the document is identified by bold brackets ([]). The content of this document is identical to 32-9392642-002, except that proprietary information is redacted. Any Rev. 001 or Rev. 002 herein refers to that in 32-9392642. Export Classification US EC: fl N Part 810 EAR ECCN: N/A If the computer software used herein is not the latest version per the EASI list, THE DOCUMENT CONTAINS ASSUMPTIONS AP 0402-01 requires that justification be provided. THAT SHALL BE VERIFIED PRIOR TO USE THE FOLLOWING COMPUTER CODES HAVE BEEN USED IN THIS DOCUMENT: CODENERSION/REV CODENERSION/REV Yes ANSYS v19.2 (See Section 5.1) No to ULNRC-06948 Page 1 of 24

frarnatorne 0402-01-FOl (Rev. 023, 06/20/2024) Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 Review Method: EXI Design Review (Detailed Check) Alternate Calculation Does this document establish design or technical requirements? YES NO Does this document contain Customer Required Format? YES NO Signature Block Name and Title Signature and Date Role Scope I Comments Kaihong Wang K WANG P All Advisory Engineer 6/4/2025 Jennifer Nelson JA NELSON Principal Engineer 6/4/2025 R All Bogdan Wasiluk BS WASILUK 6/4/2025 A All Supervisor Role Definitions: P/R/A designates Preparer (P), Reviewer (R), Approver (A); LP/LR designates Lead Preparer (LP), Lead Reviewer (LR); M designates Mentor (M); PM designates Project Manager (PM) Page 2 J LV IJLINI,VQ+O

frarnatorne 040201F01 (Rev. 023, 06/20/2024) Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 Record of Revision Revision Pages I Sections I No. Paragraphs Changed Brief Description I Change Authorization 000 All Initial release. The content of this document is identical to 32-9392642-000, except that proprietary information is redacted. The content of this revision is identical to 32-9392642-002, except that 001 All proprietary information is redacted and the Record of Revision is eliminated. See Record of Revision in 32-9392642-002 for changes. .) LU ULINf\\L..UU+O Page 3

frarriatorne Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 Table of Contents Page SIGNATUREBLOCK 2 RECORD OF REVISION 3 LIST OF TABLES 5 LIST OF FIGURES 6

1.0 INTRODUCTION

7 2.0 PURPOSE AND SCOPE 8 3.0 ANALYTICAL METHODOLOGY 8 3.1 Applied Stress Intensity FactorAcceptance Criteria (IWB-3612) 9 3.2 Primary Stress Limits (NB-3000) 9 4.0 ASSUMPTIONS 9 4.1 Unverified Assumptions 9 4.2 Justified Assumptions 9 4.3 Modeling Simplifications 10 5.0 COMPUTER USAGE II 5.1 Software 11 5.2 ComputerFiles 11 6.0 CALCULATIONS 12 6.1 Applied Stress Intensity FactorAcceptance Criteria (IWB-3612) 12 6.1.1 Key Dimension Comparison 12

6. 1.2 Material and Property Comparison I 3 6.1.3 Initial Flaw Size and Weld Residual Stress Comparison 13 6.1.4 Roll Expansion Evaluation I 3 6.1.5 Operational Transient Condition Comparison 14 6.1.6 General Corrosion and Fatigue Crack Growth Comparison 16 6.1.7 ASME Section Xl Code Edition Comparison 16 6.2 Primary Stress Limit Evaluation (ASME B&PV Code Section III NB-3000) 16 6.3 OCJ Extended to Nozzles 30 and 35 20 6.4 OCJ Extended to Nozzle 57 22 7.0

SUMMARY

OF RESULTS 23

8.0 REFERENCES

24 nciosure 3 to ULN-Ub14 Page 4

frarnatorne Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 List of Tables Page Table 5-1 : Computer Files II Table 6-1: Key Dimensions Comparison 12 Table 6-2: Material Comparison 13 Table 6-3: Transient Cycle Comparison 15 Table 6-4: Bottom Mounted Nozzle Dimensions 18 Table 6-5: Material Properties 19 Table 6-6: Dimensions Comparison BMI Nozzles 48, 30 and 35 21 Table 6-7: Dimensions Comparison Callaway Nozzle 57 and Plant A Nozzle 58 22 tznclosure 3 to ULNFtU-UbE4S Page 5

frarnatorne Document No. 32-9392644-001 Callaway Unit I RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 List of Figures Page Figure 1-1: BMI Nozzle Repair 7 Figure 6-1: Finite Element Model Mesh for Limit Load 17 Figure 6-2: Equivalent Stresses at the Final Load Step (psi) 20 3 to ULN<U-Ubt4l3 Page 6

frarnatorne Document No. 32-9392644-001 Callaway Unit I RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57

1.0 INTRODUCTION

During the Spring 2025 outage (R27) at Callaway Unit 1, the Reactor Vessel Bottom Head (RVBH) Bottom Mounted Instrumentation (BMI) Nozzle No. 48 is being repaired due to reactor coolant leakage at the interface between the RVBH and BMI nozzle. Additionally, indications were found in the J-groove welds at the BMI Nozzle No. 30, 35, and 57 locations. Per Reference [1], a portion of the existing BMI nozzle is removed, and an Alloy 52M weld pad is then deposited on the outer surface of the RVBH around the penetration using the ambient temperature machine gas tungsten arc welding (GTAW) temper bead process. An Alloy 690 replacement nozzle is then inserted into the penetration and welded to the weld pad and thimble guide tube using Alloy 52M filler metal. The general modified configuration is shown in Figure 1-1. Figure 1-1: BMI Nozzle Repair S to ULNF<(.-UbI4 Page 7

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frarnatorne Document No. 32-9392644-001 Callaway Unit I RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 1) The criteria ofIWB-361 1 or IWB-3612 (Reference [4]), The primary stress limits ofNB-3000 (Reference [5]), assuming a local area reduction ofthe pressure-retaining membrane that is equal to the area ofthe projected flaw(s) as determined by the flaw characterization rules of IWA-3 000. 3.1 Applied Stress Intensity Factor Acceptance Criteria (IWB-3612) Per Article IWB-3612, a flaw exceeding the limits ofIWB-3500 is acceptable for continued service ifthe applied stress intensity factor is less than the material fracture toughness considering the following safety factors: q10 for normal conditions J2 for emergency/faulted conditions, and conditions where pressure is less than 20% of the Design Pressure L 3.2 Primary Stress Limits (NB-3000) Per IWB-3610(d)(2), the primary stress limits ofNB-3000 (Reference [51), assuming a local area reduction of the pressure retaining membrane that is equal to the area of the flaw, shall be satisfied. This criterion is not considered in the existing analysis developed for Plant A in Reference [3]. Therefore, to evaluate the requirement, article NB-3228. 1 of Section III ofthe ASME Code is utilized. NB-3228. 1 states that the limits on General Membrane Stress Intensity (NB-322 1.1), Local Membrane Stress Intensity (NB-3221.2), and Primary Membrane plus Primary Bending Stress Intensity (NB-322 1.3) need not be satisfied at a specific location if it can be shown by limit analysis that the specified loadings do not exceed two-thirds of the lower bound collapse load. The yield strength of the material to be used in these calculations is 1.5 Sm. Per NB-3 112.1(a), the Design Pressure shall be used in showing compliance with this criterion. 4.0 ASSUMPTIONS 4.1 Unverified Assumptions There are no unverified assumptions used in this analysis. 4.2 Justified Assumptions The following justified assumptions are used in the analysis.

1) [

I

2) [

I bnclosure 3 to ULNF<U-Ub94 Page 9

frarriatorne Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57

3) [

]

4) [

]

5) [

] 4.3 Modeling Simplifications There are no modeling simplifications used in this analysis. enclosure 3 to ULN[<U-Ub94 Page 10

frarnatorne Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 5.0 COMPUTER USAGE 5.1 Software This calculation uses the following software: Controlled installation ofsoftware ANSYS Mechanical Enterprise 19.2 (Reference [7]), installed and currently maintained as a controlled container at /opt/shared/containers/rhel72ansysl 92.sff on the approved platform Lynchburg HPCv2, Reference [8]. 0 ANSYS verification tests documented in Reference [9] demonstrate that ANSYS Version 19.2 meets the requirements to be used on the HPC as a controlled-access code. Note that Version 19.2 is not the most recent approved version of ANSYS listed on EAST (Engineering Applications Software Index). However, the use ofthis version ofANSYS is acceptable since all error notices up to date have been reviewed and it is concluded that none of the errors may create erroneous results for the intent of this calculation. o The container image file rhel72 ansysl92.sif has been verified using the public key provided in Reference [9]. o Operating System: Red Hat Enterprise Linux release 8.2; Kernel: 4.18.0-193.e18.x86_64 The software is being used within its specified range of applicability as defined by validation and verification requirements defined in References [8] and [9]. 5.2 Computer Files The computer files for runs performed in revision 000 are listed in Table 5-1. [ I Table 5-1: Computer Files crc file size date file name .../official/0 1 Model 53443 3994696 May 15 2025 20:24:02 callowayBmnMesh5.inp 60939 3714 May 12 2025 16:39:42 materials_LL.inp ./official/O2Runs 22932 2343 May 15 2025 20:24:15 59335 104028 May 15 2025 20:35:16 limitLoadRun.mac limitLoadRun.out Iznclosure s to ULIN[A-Ub4 Page 11

frarnatonie Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 6.0 CALCULATIONS 6.1 Applied Stress Intensity Factor Acceptance Criteria (IWB-3612) The LEFM analysis documented in Reference [3] for Plant A is equivalent or bounding of the current BMI nozzle No. 48 repair for Callaway Unit 1 as technically justified in Sections 6.1.1 through 6.1.7. 6.1.1 Key Dimension Comparison Key dimensions between the RVBH BMI nozzles for Callaway Unit 1 and Plant A are compared in Table 6-1.

== Conclusion:== In terms of geometry, Plant A penetration No. 58 bounds Callaway Unit 1 penetration No. 48. Table 6-1: Key Dimensions Comparison hnclosure 3 to ULN<U-Ut54 Page 12

frarnatorne Document No. 32-9392644-001 CaHaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 6.1.2 Material and Property Comparison The pertinent materials and properties for the RVBH BMI nozzles for Callaway and Plant A are compared in Table 6-2. [ ]

== Conclusion:== In terms ofmaterial, Plant A bounds Callaway Unit 1. Table 6-2: Material Comparison 6.1.3 Initial Flaw Size and Weld Residual Stress Comparison

== Conclusion:== In terms of initial flaw size and considering comparable conditions for both Plant A and Callaway Unit 1, they are considered equivalent. 6.1.4 Roll Expansion Evaluation For Plant A, possible roll expansion of the original nozzle to eliminate leakage is evaluated in Reference [14]. For the Callaway Unit 1 repair, roll expansion is also specified as an optional step in Reference [2].

== Conclusion:== It is considered appropriate for this OCJ to perform the comparative evaluation using the analysis provided in Reference [3], which does not include roll expansion. hnclosure 3 to ULN<(>Ub94 Page 13

frarnatorrie Document No. 32-9392644-001 Callaway Unit I RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 6.1.5 Operational Transient Condition Comparison The operational stresses and transient cycles evaluated in Reference [3] for Plant A are compared to the applicable conditions for Callaway Unit 1. F

== Conclusion:== In terms of operational transient conditions, Plant A bounds Callaway Unit 1 given the significant number of years Plant A is evaluated for, compared to one cycle for Callaway Unit 1. ncIosure 3 to ULNF<U-UbI4 Page 14

Controlled Document frarnatorne Document No. 32-9392644-001 Callaway Unit I RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 Table 6-3: Transient Cycle Comparison F znclosure S to ULN<U-UbI4 Page 15

frarnatorne Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 6.1.6 General Corrosion and Fatigue Crack Growth Comparison

== Conclusion:== Considering general corrosion and fatigue crack growth, Plant A bounds Callaway Unit 1.

6.1.7 ASME Section Xl Code Edition Comparison

== Conclusion:== In terms ofASME Section XI code year, Plant A bounds Callaway Unit 1 6.2 Primary Stress Limit Evaluation (ASME B&PV Code Section III NB-3000) The acceptance criteria of Section 3. 1 (c) of Code Case N-749 and Article IWB-36 1 0(d)(2) require that the primary stress limits ofArticle NB-3000 (Reference [5]) are met assuming a local area reduction ofthe pressure retaining membrane that is equal to the area ofthe flaw. To evaluate the requirement, Article NB-3228. 1 of Section III ofthe ASME B&PV Code (Reference [5]) is utilized. Article NB-3228.1 states that the limits on General Membrane Stress Intensity (NB-3221.1), Local Membrane Stress Intensity (NB-322 1.2), and Primary Membrane plus Primary Bending Stress Intensity (NB-322 1.3) need not be satisfied at a specific location if it can be shown by limit analysis that the specified loadings do not exceed two-thirds ofthe lower bound collapse load. The yield strength to be used in these calculations is 1.55m. Per Article NB-31 12.1(a), the design pressure shall be used in showing compliance with this limit. This condition is equivalent to showing that the structure does not collapse at a pressure equal to 1.5 times the design pressure ([ ] Reference [ 17] ). In terms of finite element (FE) method results, plastic collapse of the structure is equivalent to [ ] To demonstrate this by the FE method, cladding, [ ] J-groove weld, buttering material, and portions of the RVBH wall are removed in the FE model to represent the material removed by the postulated J-Groove flaws and the crack growth. The removed material represents a conservative final flaw width and depth of [ ] which bounds the final fatigue plus corrosion flaw size after 1.5 years of crack growth as calculated in Section 6.1.6. hnclosure to ULN<U-UbY4 Page 16

Controlfr frarnatorne Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 The purpose ofthe limit load analysis is to address the primary stress criteria ofNB-3000 with respect to the volume of material removed. Explicit calculation of Stress Intensity Factors (SIF) due to the flaws shape are performed in the LEFM assessment as discussed in Section 6.1 using the criteria from IWB-3612 (Reference [4]). For the purpose of the primary stress criteria, the volume removed in the FE model is bounding and conservative. [ ] The FE mesh utilized is shown in Figure 6-1. Figure 6-1: Finite Element Model Mesh for Limit Load The detailed dimensions of the lower instrument nozzle modeled are obtained from References [2] and [18]. Key dimensions are listed in Table 6-4. tznclosure 3 to ULNFtU-U594t Page 17

frarnatorne Document No. 32-9392644-001 CaUaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 Table 6-4: Bottom Mounted Nozzle Dimensions Description Value Reference(s) RV bottom head base metal inside radius (IR) [ ] [2] RV bottom head base metal thickness (minimum) [ ] [2] Original nozzle bore ID [ ] [2] Repair weld pad thickness [ ] [2] Replacement nozzle ID [ ] [18] Replacement nozzle bore ID [ ] [2] Replacement nozzle OD [ 1 [2] Penetration horizonal distance to RVBH center [ ] [22] (outermost nozzle) Note: (1) For nozzle #48, the counterbore diameter extending from the OD of the head approximately [ 1 (2) Bore ID; showing dimension used in FE model, replacement nozzle OD is determined in field. (3)[ ] [ I The material properties are listed in Table 6-5, which are considered at a temperature of 700°F, which bounds the design temperature of 650°F (Reference [17]). The materials are considered as elastic-perfectly plastic. The value of yield strength used is based on Sm and is defined as Sy = 1.5 Sm. hnclosure 3 to ULNFU-UI5EJ4 Page 18

framatome Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 Table 6-5: Material Properties 700 RV Bottom Head: SA-533 Grade B Class 1 (C-Mn-Mo 0.4-0.7Ni) 7.44E-06 2.66E+07 0.3 26.7 Replacement Nozzle, Weld Pad, and New J-groove Weld: Alloy 690/Alloy 52M2 Temperature (°F) u (1/°F) E (psi) v (-) Sm (ksi) Sy (ksi) (3) 700 8.3E-06 2.75E+07 0.31 23.3 34.95 Note(s): [ [ 1. Material properties for RV bottom head per Reference [19]. 2. Material properties for the replacement nozzle, weld pad, and new J-groove weld per Reference [20]. 3. Sy1.5Sm. I ] The analysis was run up to a pressure of [ ] psia which is [ ] which is about [ ] times the design pressure, exceeding the requirement of 1.5 times the design pressure. The equivalent stress at the last converged load step is shown in Figure 6-2. 3 to ULNI<U-UbE4 Temperature (°F) u (1/°F) E (psi) v (-) Sm (ksi) S (ksi) 40.05 Page 19

frarnatorne Document No. 32-9392644-001 Callaway Unit 1 RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 Figure 6-2: Equivalent Stresses at the Final Load Step (psi) 6.3 OCJ Extended to Nozzles 30 and 35 In addition to Nozzle 48, the same half-nozzle repair modification is to be performed for BMI Nozzles 30 and 35 per Reference [1]. Rev. 000 of the report addresses only the modification of BMI Nozzle 48. Justification is provided in this section that the analysis in Rev. 000 is also applicable to the modification of BMI Nozzles 30 and

35. A major dimension comparison between these nozzles is listed in Table 6-6; values are taken from the main body of References [11] and [13] as well as from References [21] and [22].

3 to ULNF<t.-Ub4 Page 20

Controlled Dor frarnatorrie Document No. 32-9392644-001 Callaway Unit I RVBH BMI Nozzle As-Left J-Groove Weld One Cycle Justification for Nozzles 48, 30, 35 and 57 Table 6-6: Dimensions Comparison BMI Nozzles 48, 30 and 35

== Conclusion:== Evaluation of the BMI Nozzle 48 presented in Sections 6.1 and 6.2 is also applicable to the modification of BMI Nozzles 30 and 35. tznciosure 3 to ULN1<U-Ub94 Page 21

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