WBL-20-004, Analysis of Capsule U from Watts Bar Unit 2 Reactor Vessel Radiation Surveillance Program

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Analysis of Capsule U from Watts Bar Unit 2 Reactor Vessel Radiation Surveillance Program
ML20107F717
Person / Time
Site: Watts Bar Tennessee Valley Authority icon.png
Issue date: 04/16/2020
From: Anthony Williams
Tennessee Valley Authority
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
WBL-20-004 WCAP-18518-NP
Download: ML20107F717 (188)
v • d • e


Text

Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381 April 16, 2020 WBL-20-004 10 CFR 50 Appendix H ATTN: Document Control Desk .

U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391

Subject:

Watts Bar Nuclear Plant (WBN} Unit 2 -Analysis of Capsule U from Watts Bar Unit 2 Reactor Vessel Radiation Surveillance Program In accordance with 10 CFR 50, Appendix H.IV.A, TVA is submitting the Technical Report WCAP-18518-NP, "Analysis of Capsule U from the Watts Bar Unit 2 Reactor Vessel Radiation Surveillance Program," Revision 0, dated March 2020. Westinghouse Electric Company LLC developed this report, which details the test results of Surveillance Capsule U withdrawn in the End of Cycle (EOC) 2 refueling outage after 2.0 effective full power years (EFPY) of operation. This WCAP is provided in the enclosure.

The reactor vessel capsule fluence values for WBN Unit 2 Capsule U were determined using the RAPTOR-M3G computer code as described in WCAP-18124-NP-A, Revision 0 "Fluence Determination with RAPTOR-M3G and FERRET." Although this WCAP has been found acceptable by NRC for referencing in licensing applications, it has not yet been incorporated into the WBN licensing basis. A license amendment to this effect is planned for submission by August 2020.

There are no regulatory commitments contained in this letter. Please direct any questions concerning this matter to Tony Brown, WBN Licensing Manager, at (423) 365-7720.

Anthony L. Williams IV Site Vice President Watts Bar Nuclear Plant

U.S. Nuclear Regulatory Commission WBL-20-004 Page 2 April 16, 2020

Enclosure:

WCAP-18518-NP, "Analysis of Capsule U from the Watts Bar Unit 2 Reactor Vessel Radiation Surveillance Program," Revision 0, dated March 2020.

cc (Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant

Westinghouse Non-Proprietary Class 3 WCAP-18518-NP March 2020 Revision 0 Analysis of Capsule U from the Watts Bar Unit 2 Reactor Vessel Radiation Surveillance Program

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 WCAP-18518-NP Revision 0 Analysis of Capsule U from the Watts Bar Unit 2 Reactor Vessel Radiation Surveillance Program D. Brett Lynch*

RV/CV Design & Analysis Greg A. Fischer*

Nuclear Operations & Radiation Analysis March 2020 Reviewers: J. Brian Hall*

Churchill Lab Services Benjamin W. Amiri*

Nuclear Operations & Radiation Analysis Approved: Lynn A. Patterson*, Manager RV/CV Design & Analysis Laurent P. Houssay*, Manager Nuclear Operations / Radiation Analysis

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

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

© 2020 Westinghouse Electric Company LLC All Rights Reserved

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 ii TABLE OF CONTENTS LIST OF TABLES ....................................................................................................................................... iii LIST OF FIGURES ...................................................................................................................................... v EXECUTIVE

SUMMARY

......................................................................................................................... vii 1

SUMMARY

OF RESULTS ................................................................................................................. 1-1 2 INTRODUCTION ............................................................................................................................... 2-1 3 BACKGROUND ................................................................................................................................. 3-1 4 DESCRIPTION OF PROGRAM ........................................................................................................ 4-1 5 TESTING OF SPECIMENS FROM CAPSULE U ............................................................................ 5-1 5.1 OVERVIEW .................................................................................................................... 5-1 5.2 CHARPY V-NOTCH IMPACT TEST RESULTS ........................................................... 5-2 5.3 TENSILE TEST RESULTS ............................................................................................. 5-4 6 RADIATION ANALYSIS AND NEUTRON DOSIMETRY.............................................................. 6-1

6.1 INTRODUCTION

........................................................................................................... 6-1 6.2 DISCRETE ORDINATES ANALYSIS ........................................................................... 6-1 6.3 NEUTRON DOSIMETRY .............................................................................................. 6-4 6.4 CALCULATIONAL UNCERTAINTIES ........................................................................ 6-4 7 SURVEILLANCE CAPSULE REMOVAL SCHEDULE................................................................... 7-1 8 REFERENCES .................................................................................................................................... 8-1 APPENDIX A VALIDATION OF THE RADIATION TRANSPORT MODELS BASED ON NEUTRON DOSIMETRY MEASUREMENTS ................................................................................ A-1 APPENDIX B LOAD-TIME RECORDS FOR CHARPY SPECIMEN TESTS FROM CAPSULE U

........................................................................................................................................ B-1 APPENDIX C CHARPY V-NOTCH PLOTS FOR BASELINE AND CAPSULE U USING SYMMETRIC HYPERBOLIC TANGENT CURVE-FITTING METHOD .................. C-1 APPENDIX D WATTS BAR UNIT 2 SURVEILLANCE PROGRAM CREDIBILITY EVALUATION

........................................................................................................................................ D-1 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 iii LIST OF TABLES Table 4-1 Chemical Composition (wt. %) of the Watts Bar Unit 2 Reactor Vessel Surveillance Materials (Unirradiated)................................................................................................... 4-3 Table 4-2 Heat Treatment History of the Watts Bar Unit 2 Reactor Vessel Surveillance Materials

......................................................................................................................................... 4-4 Table 5-1 Charpy V-notch Data for the Watts Bar Unit 2 Intermediate Shell Forging 05 Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) (Tangential Orientation) ......................... 5-5 Table 5-2 Charpy V-notch Data for the Watts Bar Unit 2 Intermediate Shell Forging 05 Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) (Axial Orientation) ................................. 5-6 Table 5-3 Charpy V-notch Data for the Watts Bar Unit 2 Surveillance Program Weld Material (Heat

  1. 895075) Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV)........................... 5-7 Table 5-4 Charpy V-notch Data for the Watts Bar Unit 2 Heat-Affected Zone (HAZ) Material Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) ............................................ 5-8 Table 5-5 Instrumented Charpy Impact Test Results for the Watts Bar Unit 2 Intermediate Shell Forging 05 Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) (Tangential Orientation) ...................................................................................................................... 5-9 Table 5-6 Instrumented Charpy Impact Test Results for the Watts Bar Unit 2 Intermediate Shell Forging 05 Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) (Axial Orientation)

....................................................................................................................................... 5-10 Table 5-7 Instrumented Charpy Impact Test Results for the Watts Bar Unit 2 Surveillance Program Weld Material (Heat # 895075) Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV)

....................................................................................................................................... 5-11 Table 5-8 Instrumented Charpy Impact Test Results for the Watts Bar Unit 2 Heat-Affected Zone (HAZ) Material Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV)................ 5-12 Table 5-9 Effect of Irradiation to 6.04 x 1018 n/cm2 (E > 1.0 MeV) on the Charpy V-Notch Toughness Properties of the Watts Bar Unit 2 Reactor Vessel Surveillance Capsule U Materials

....................................................................................................................................... 5-13 Table 5-10 Comparison of the Watts Bar Unit 2 Surveillance Material 30 ft-lb Transition Temperature Shifts and Upper-Shelf Energy Decreases with Regulatory Guide 1.99, Revision 2, Predictions ..................................................................................................................... 5-14 Table 5-11 Tensile Properties of the Watts Bar Unit 2 Capsule U Reactor Vessel Surveillance Materials Irradiated to 6.04 x 1018 n/cm2 (E > 1.0 MeV)............................................................... 5-15 Table 6-1 Calculated Neutron Exposure Rates at the Geometric Center of the Surveillance Capsules

......................................................................................................................................... 6-7 Table 6-2 Calculated Fast Neutron (E > 1.0 MeV) Fluence at the Geometric Center of the Surveillance Capsules ...................................................................................................... 6-7 Table 6-3 Calculated Iron Atom Displacements (dpa) at the Geometric Center of the Surveillance Capsules ........................................................................................................................... 6-7 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 iv Table 6-4 Calculated Neutron Fluence Rate for Selected Pressure Vessel Materials....................... 6-8 Table 6-5 Calculated Neutron Fluence for Selected Pressure Vessel Materials ............................... 6-9 Table 6-6 Calculated dpa/s for Selected Pressure Vessel Materials ............................................... 6-10 Table 6-7 Calculated dpa for Selected Pressure Vessel Materials .................................................. 6-11 Table 6-8 Calculated Surveillance Capsule Lead Factors .............................................................. 6-12 Table 7-1 Surveillance Capsule Withdrawal Schedule .................................................................... 7-1 Table A-1 Nuclear Parameters Used in the Evaluation of Neutron Sensors .................................... A-9 Table A-2 Monthly Thermal Generation for the Watts Bar Unit 2 Reactor ................................... A-10 Table A-3 Surveillance Capsule Fluence Rates for Cj Calculation, Core Midplane Elevation .... A-11 Table A-4 Surveillance Capsule Cj Factors, Core Midplane Elevation ......................................... A-12 Table A-5 Measured Sensor Activities and Reaction Rates for Surveillance Capsule U .............. A-13 Table A-6 Least-Squares Evaluation of Dosimetry in Capsule U (34° Dual Position, Core Midplane, Withdrawn at the End of Cycle 2) ................................................................................ A-14 Table A-7 Comparison of Measured/Calculated (M/C) Sensor Reaction Rate Ratios for Fast Neutron Threshold Reactions ..................................................................................................... A-15 Table A-8 Comparison of Best-Estimate/Calculated (BE/C) Exposure Rate Ratios ..................... A-15 Table C-1 Upper-Shelf Energy Values (ft-lb) Fixed in CVGRAPH ................................................ C-2 Table D-1 Mean Chemical Composition and Temperature for Weld Heat # 895075 ...................... D-5 Table D-2 Heat # 895075 Interim Chemistry Factor Using All Available Surveillance Data.......... D-6 Table D-3 Heat # 895075 Surveillance Capsule Data Scatter about the Best-Fit Line Using All Available Surveillance Data ............................................................................................ D-7 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 v LIST OF FIGURES Figure 4-1 Watts Bar Unit 2 Irradiation Capsule Assembly and Reactor Vessel Location ................ 4-5 Figure 4-2 Specimen Locations in the Watts Bar Unit No. 2 Surveillance Test Capsules................. 4-6 Figure 5-1 Charpy V-Notch Impact Energy vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation) ................................................ 5-16 Figure 5-2 Charpy V-Notch Lateral Expansion vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation) ................................................ 5-17 Figure 5-3 Charpy V-Notch Percent Shear vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation) ................................................ 5-18 Figure 5-4 Charpy V-Notch Impact Energy vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation) ........................................................ 5-19 Figure 5-5 Charpy V-Notch Lateral Expansion vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation) ........................................................ 5-20 Figure 5-6 Charpy V-Notch Percent Shear vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation) ........................................................ 5-21 Figure 5-7 Charpy V-Notch Impact Energy vs. Temperature for Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075) .................................................. 5-22 Figure 5-8 Charpy V-Notch Lateral Expansion vs. Temperature for Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075) .................................................. 5-23 Figure 5-9 Charpy V-Notch Percent Shear vs. Temperature for Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075) .................................................. 5-24 Figure 5-10 Charpy V-Notch Impact Energy vs. Temperature for Watts Bar Unit 2 Reactor Vessel Heat-Affected Zone Material .................................................................................................. 5-25 Figure 5-11 Charpy V-Notch Lateral Expansion vs. Temperature for Watts Bar Unit 2 Reactor Vessel Heat-Affected Zone Material ......................................................................................... 5-26 Figure 5-12 Charpy V-Notch Percent Shear vs. Temperature for Watts Bar Unit 2 Reactor Vessel Heat-Affected Zone Material .................................................................................................. 5-27 Figure 5-13 Charpy Impact Specimen Fracture Surfaces for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation) ................................................ 5-28 Figure 5-14 Charpy Impact Specimen Fracture Surfaces for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation) ........................................................ 5-29 Figure 5-15 Charpy Impact Specimen Fracture Surfaces for the Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075) .................................................. 5-30 Figure 5-16 Charpy Impact Specimen Fracture Surfaces for the Watts Bar Unit 2 Reactor Vessel Heat-Affected Zone Material .................................................................................................. 5-31 Figure 5-17 Tensile Properties for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation) ................................................................................................. 5-32 Figure 5-18 Tensile Properties for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation) ......................................................................................................... 5-33 Figure 5-19 Tensile Properties for Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075) ............................................................................................................. 5-34 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 vi Figure 5-20 Fractured Tensile Specimens from Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation) [Scale in 1/10th of inch]........................................ 5-35 Figure 5-21 Fractured Tensile Specimens from Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation) [Scale in 1/10th of inch]................................................ 5-36 Figure 5-22 Fractured Tensile Specimens from Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075) [Scale in 1/10th of inch] ............................................... 5-37 Figure 5-23 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BL1, Tested at 78°F ................................................................................................................ 5-38 Figure 5-24 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BL2, Tested at 300°F .............................................................................................................. 5-38 Figure 5-25 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BL3, Tested at 550°F .............................................................................................................. 5-38 Figure 5-26 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BT1, Tested at 78°F ................................................................................................................ 5-39 Figure 5-27 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BT2, Tested at 300°F .............................................................................................................. 5-39 Figure 5-28 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BT3, Tested at 550°F .............................................................................................................. 5-39 Figure 5-29 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BW1, Tested at 78°F ................................................................................................................ 5-40 Figure 5-30 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BW2, Tested at 300°F .............................................................................................................. 5-40 Figure 5-31 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BW3, Tested at 550°F .............................................................................................................. 5-40 Figure 6-1 Watts Bar Unit 2 Plan View of the Reactor Geometry at the Core Midplane 15.0° Neutron Pad Configuration .......................................................................................................... 6-13 Figure 6-2 Watts Bar Unit 2 Plan View of the Reactor Geometry at the Core Midplane 17.5° Neutron Pad Configuration .......................................................................................................... 6-14 Figure 6-3 Watts Bar Unit 2 Plan View of the Reactor Geometry at the Core Midplane 20.0° Neutron Pad Configuration .......................................................................................................... 6-15 Figure 6-4 Watts Bar Unit 2 Section View of the Reactor Geometry at the 34.0° Azimuthal Angle -

20.0° Neutron Pad Configuration .................................................................................. 6-16 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 vii EXECUTIVE

SUMMARY

The purpose of this report is to document the testing results of surveillance Capsule U from Watts Bar Unit 2. Capsule U was removed at 2.0 effective full-power years (EFPY) and post-irradiation mechanical tests of the Charpy V-notch and tensile specimens were performed. A fluence evaluation utilizing the neutron transport and dosimetry cross-section libraries was derived from the Evaluated Nuclear Data File (ENDF) database (specifically, ENDF/B-VI). Capsule U received a fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) after irradiation to 2.0 EFPY. The peak clad/base metal interface vessel fluence after 32 EFPY (end-of-license) of plant operation is projected to be 1.94 x 1019 n/cm2 (E > 1.0 MeV).

This evaluation led to the following conclusions: (1) The measured shift in the 30 ft-lb transition temperature of the surveillance forging and weld materials contained in Watts Bar Unit 2 Capsule U are approximately equal to or less than the Regulatory Guide 1.99, Revision 2 [Ref. 1] predictions. (2) The measured percent decreases in upper-shelf energy for the surveillance forging and weld materials contained in Watts Bar Unit 2 Capsule U are typically less than the Regulatory Guide 1.99, Revision 2 [Ref. 1]

predictions. The exception is Intermediate Shell Forging 05 in the tangential direction, which experienced a higher than predicted decrease in the upper-shelf energy. (3) The Watts Bar Unit 2 surveillance weld (Heat # 895075) data and sister-plant data are judged to be credible. This credibility evaluation can be found in Appendix D.

Lastly, a brief summary of the Charpy V-notch testing can be found in Section 1. All Charpy V-notch data was plotted using a symmetric hyperbolic tangent curve-fitting program.

WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 1-1 1

SUMMARY

OF RESULTS The analysis of the reactor vessel materials contained in surveillance Capsule U, the first capsule removed and tested from the Watts Bar Unit 2 reactor pressure vessel, led to the following conclusions:

Charpy V-notch test data were plotted using a symmetric hyperbolic tangent curve-fitting program.

Appendix C presents the CVGRAPH, Version 6.02, Charpy V-notch plots for Capsule U, along with the program baseline data.

Capsule U received an average fast neutron fluence (E > 1.0 MeV) of 6.04 x 1018 n/cm2 after 2.0 effective full-power years (EFPY) of plant operation.

Irradiation of the reactor vessel Intermediate Shell Forging 05 Charpy specimens, oriented with the longitudinal axis of the specimen parallel to the major rolling direction (tangential orientation), resulted in an irradiated 30 ft-lb transition temperature (T30) of -15.6F. This results in a 30 ft-lb transition temperature increase of 26.7F for the tangentially oriented specimens.

Irradiation of the reactor vessel Intermediate Shell Forging 05 Charpy specimens, oriented with the longitudinal axis of the specimen perpendicular to the major rolling direction (axial orientation),

resulted in an irradiated 30 ft-lb transition temperature (T30) of -20.5F. This results in a 30 ft-lb transition temperature increase of 21.3F for the axially oriented specimens.

Irradiation of the Surveillance Program Weld Material (Heat # 895075) Charpy specimens resulted in an irradiated 30 ft-lb transition temperature (T30) of -25.1F. This results in a 30 ft-lb transition temperature increase of 32.6F.

Irradiation of the Heat-Affected Zone (HAZ) Material Charpy specimens resulted in an irradiated 30 ft-lb transition temperature (T30) of -103.4F. This results in a 30 ft-lb transition temperature reduction of 1.6F. Note that physically a reduction in T30 should not occur.

The average upper-shelf energy of Intermediate Shell Forging 05 (tangential orientation) resulted in an average energy decrease of -45 ft-lb after irradiation. This decrease results in an irradiated average upper-shelf energy of 130 ft-lb for the tangentially oriented specimens.

The average upper-shelf energy of Intermediate Shell Forging 05 (axial orientation) resulted in an average energy decrease of -5 ft-lb after irradiation. This decrease results in an irradiated average upper-shelf energy of 105 ft-lb for the axially oriented specimens.

The average upper-shelf energy of the Surveillance Program Weld Material (Heat # 895075) Charpy specimens resulted in an average energy decrease of -9 ft-lb after irradiation. This decrease results in an irradiated average upper-shelf energy of 135 ft-lb for the weld metal specimens.

The average upper-shelf energy of the HAZ Material Charpy specimens resulted in an average energy decrease of -12 ft-lb after irradiation. This decrease results in an irradiated average upper-shelf energy of 118 ft-lb for the HAZ Material.

WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 1-2 Comparisons of the measured 30 ft-lb shift in transition temperature values and upper-shelf energy decreases to those predicted by Regulatory Guide 1.99, Revision 2 [Ref. 1] for the Watts Bar Unit 2 reactor vessel surveillance materials are presented in Table 5-10.

Based on the credibility evaluation presented in Appendix D, the Watts Bar Unit 2 surveillance weld material (Heat # 895075) is credible.

The maximum calculated 32 EFPY (end-of-license) neutron fluence (E > 1.0 MeV) for the Watts Bar Unit 2 reactor vessel beltline using the Regulatory Guide 1.99, Revision 2 [Ref. 1] attenuation formula (i.e., Equation # 3 in the Guide) is as follows:

Calculated (32 EFPY): Vessel peak clad/base metal interface fluence* = 1.94 x 1019 n/cm2 Vessel peak quarter-thickness (1/4T) fluence = 1.17 x 1019 n/cm2

  • This fluence value is documented in Table 6-5.

WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 2-1 2 INTRODUCTION This report presents the results of the examination of Capsule U, the first capsule removed and tested in the continuing surveillance program, which monitors the effects of neutron irradiation on the Tennessee Valley Authority (TVA) Watts Bar Unit 2 reactor pressure vessel materials under actual operating conditions.

The surveillance program for the Watts Bar Unit 2 reactor pressure vessel materials was designed and recommended by Westinghouse Electric Company LLC. A detailed description of the surveillance program is contained in WCAP-9455 [Ref. 2] Tennessee Valley Authority Watts Bar Unit No. 2 Reactor Vessel Radiation Surveillance Program. The surveillance program covers the 40-year design life of the reactor pressure vessel and is based on ASTM E185-73 [Ref. 3], Standard Recommended Practice for Surveillance Tests for Nuclear Reactor Vessels. Capsule U was removed from the reactor after 2.0 EFPY of exposure and shipped to the Westinghouse Churchill Laboratory Services, where the post-irradiation mechanical testing of the Charpy V-notch impact and tensile surveillance specimens was performed.

This report summarizes the testing and post-irradiation data obtained from surveillance Capsule U removed from the Watts Bar Unit 2 reactor vessel and presents the analysis of the data.

WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 3-1 3 BACKGROUND The ability of the large steel pressure vessel containing the reactor core and its primary coolant to resist fracture constitutes an important factor in ensuring safety in the nuclear industry. The beltline region of the reactor pressure vessel is the most critical region of the vessel because it is subjected to significant fast neutron bombardment. The overall effects of fast neutron irradiation on the mechanical properties of low-alloy, ferritic pressure vessel steels such as SA508 Class 2 (base material of the Watts Bar Unit 2 reactor pressure vessel beltline) are well documented in the literature. Generally, low-alloy ferritic materials show an increase in hardness and tensile properties and a decrease in ductility and toughness during high-energy irradiation.

A method for ensuring the integrity of reactor pressure vessels has been presented in Fracture Toughness Criteria for Protection Against Failure, Appendix G to Section XI of the ASME Boiler and Pressure Vessel Code [Ref. 4]. The method uses fracture mechanics concepts and is based on the reference nil-ductility transition temperature (RTNDT).

RTNDT is defined as the greater of either the drop-weight nil-ductility transition temperature (NDTT) per American Society of Testing and Materials (ASTM) E208-06 [Ref. 5] or the temperature 60F less than the 50 ft-lb (and 35-mil lateral expansion) temperature as determined from Charpy specimens oriented perpendicular (axial) to the major rolling direction of the forging. The RTNDT of a given material is used to index that material to a reference stress intensity factor curve (KIc curve) which appears in Appendix G to Section XI of the ASME Code [Ref. 4]. The KIc curve is a lower bound of static fracture toughness results obtained from several heats of pressure vessel steel. When a given material is indexed to the KIc curve, allowable stress intensity factors can be obtained for this material as a function of temperature. Allowable operating limits can then be determined using these allowable stress intensity factors.

RTNDT and, in turn, the operating limits of nuclear power plants, are adjusted to account for the effects of radiation on the reactor vessel material properties. The changes in mechanical properties of a given reactor pressure vessel steel, due to irradiation, are monitored by a reactor vessel surveillance program, such as the Watts Bar Unit 2 reactor vessel radiation surveillance program, in which a surveillance capsule is periodically removed from the operating nuclear reactor and the encapsulated specimens are tested. The increase in the average Charpy V-notch 30 ft-lb temperature (RTNDT) due to irradiation is added to the initial RTNDT, along with a margin (M) to cover uncertainties, to adjust the RTNDT (ART) for radiation embrittlement. This ART (initial RTNDT + M + RTNDT) is used to index the material to the KIc curve and, in turn, to set operating limits for the nuclear power plant that take into account the effects of irradiation on the reactor vessel materials.

WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 4-1 4 DESCRIPTION OF PROGRAM Six surveillance capsules for monitoring the effects of neutron exposure on the Watts Bar Unit 2 reactor pressure vessel core region (beltline) materials were inserted in the reactor vessel prior to initial plant startup. The six capsules were positioned in the reactor vessel, as shown in Figure 4-1, between the neutron shield pads and the vessel wall, at various azimuthal locations for this Westinghouse four-loop plant. The vertical center of the capsules is opposite the vertical center of the core. The capsules contain specimens made from the following:

Intermediate Shell Forging 05 (tangential orientation), Heat # 527828 Intermediate Shell Forging 05 (axial orientation), Heat # 527828 Weld metal fabricated with weld wire heat no. 895075 with type Grau L.O. (LW320) flux, lot P46 which is equivalent to the heat number, Flux Type, and Flux Lot number used in the actual fabrication of the intermediate shell to lower shell circumferential weld seam Weld heat-affected zone (HAZ) material of Intermediate Shell Forging 05 Test material obtained from the Intermediate Shell Forging 05 (after thermal heat treatment and forming of the forging) was taken at least one forging thickness from the quenched edges of the forging. All test specimens were machined from the 1/4 thickness location of the forging after performing a simulated post-weld stress-relieving treatment on the test material. Test specimens were also removed from the weld and heat-affected zone metal of stress-relieved weldments joining Intermediate Shell Forging 05 and Lower Shell Forging 04. All heat-affected zone specimens were obtained from the weld heat-affected zone of Intermediate Shell Forging 05.

Charpy V-notch impact specimens from Intermediate Shell Forging 05 were machined in the tangential orientation (longitudinal axis of the specimen parallel to the major rolling direction) and also in the axial orientation (longitudinal axis of the specimen perpendicular to the major rolling direction). The core-region weld Charpy impact specimens were machined from the weldment such that the long dimension of each Charpy specimen was perpendicular to the weld direction. The notch of the weld metal Charpy specimens was machined such that the direction of crack propagation in the specimen was in the welding direction.

Tensile specimens from Intermediate Shell Forging 05 were machined both in the tangential and axial orientations. Tensile specimens from the weld metal were oriented perpendicular to the welding direction.

Compact tension test specimens from Intermediate Shell Forging 05 were machined in both the tangential and axial orientations. Compact tension test specimens from the weld metal were machined perpendicular to the weld direction with the notch oriented in the direction of the weld. All specimens were fatigue precracked according to ASTM E399 [Ref. 6].

All six capsules contain dosimeter wires of pure iron, copper, nickel, and aluminum-0.15 weight percent cobalt (cadmium-shielded and unshielded). In addition, cadmium-shielded dosimeters of Neptunium (237Np) and Uranium (238U) were placed in the capsules to measure the integrated flux at specific neutron energy levels.

WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 4-2 The capsules contain thermal monitors made from two low-melting-point eutectic alloys, which were sealed in Pyrex tubes. These thermal monitors were located in three different positions in the capsule. These thermal monitors are used to detect the maximum temperature attained by the test specimens during irradiation. The composition of the two eutectic alloys and their melting points are as follows:

2.5% Ag, 97.5% Pb Melting Point: 579°F (304°C) 1.75% Ag, 0.75% Sn, 97.5% Pb Melting Point: 590°F (310°C)

The chemical composition and the heat treatment of the various mechanical specimens in Capsule U are presented in Table 4-1 and Table 4-2, respectively. The data in the tables were obtained from the original surveillance program report, WCAP-9455 [Ref. 2], Appendix A.

Capsule U was removed after 2.0 EFPY of plant operation. This capsule contained Charpy V-notch specimens, pre-cracked bend bar specimens, compact tension specimens, tensile specimens, dosimeters, and thermal monitors.

The arrangement of the various mechanical specimens, dosimeters and thermal monitors contained in Capsule U is shown in Figure 4-2.

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Westinghouse Non-Proprietary Class 3 4-3 Table 4-1 Chemical Composition (wt. %) of the Watts Bar Unit 2 Reactor Vessel Surveillance Materials (Unirradiated)

Surveillance Weld Metal(b)

Element Intermediate Shell Forging 05(a)

Westinghouse(c) Rotterdam(d)

C 0.21 0.22 0.060 0.069 S 0.012 0.011 0.008 0.010 Co < 0.01 0.007 0.015 -----

Cu 0.05 0.07 0.016 0.05 Si 0.28 0.26 0.21 0.22 Mo 0.55 0.60 0.52 0.56 Ni 0.78 0.80 0.69 0.70 Mn 0.72 0.68 1.80 1.97 Cr 0.28 0.32 0.020 0.05 V < 0.01 0.01 < 0.001 -----

P 0.012 0.011 0.015 0.010 Al < 0.01 0.003 ----- -----

Notes:

(a) All analyses were conducted by Rotterdam Dockyard Company/Krupp ladle analysis.

(b) The surveillance weldment is identical to the closing girth seam weldment between forging 04 and

05. The closing seam used weld wire heat no. 895075 with type Grau L.O. (LW320) flux, lot P46, except for the 1-inch root pass at the I.D. of the vessel. This root pass used weld wire heat no.

899680 with type Grau L.O. (LW320) flux, lot P23, with an as-deposited copper and phosphorous content of 0.03 and 0.009, respectively. The surveillance weldment specimens were not removed from this root area.

(c) All analyses were performed by Westinghouse.

(d) All analyses were performed by Rotterdam Dockyard Company.

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Westinghouse Non-Proprietary Class 3 4-4 Table 4-2 Heat Treatment History of the Watts Bar Unit 2 Reactor Vessel Surveillance Materials Temperature Time Material Cooling

(°F) (hr)

Intermediate shell 1675-1700 4 Water-quenched forging 05(a) 1230-1240 6 Air-cooled 1140 +/- 25 22 Furnace-cooled Weldment 1140 +/- 25 14 Furnace-cooled Notes:

(a) The surviellence forging also received the stress relief treatment given to the weld.

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Westinghouse Non-Proprietary Class 3 4-5 Figure 4-1 Watts Bar Unit 2 Irradiation Capsule Assembly and Reactor Vessel Location WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 4-6 LEGEND:

BL - INTERMEDIATE FORGING 05, HEAT NO. 527828 (TANGENTIAL)

BT - INTERMEDIATE FORGING 05, HEAT NO. 527828 (AXIAL)

BW - WELD METAL BH - HEAT-AFFECTED ZONE MATERIAL Figure 4-2 Specimen Locations in the Watts Bar Unit No. 2 Surveillance Test Capsules WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-1 5 TESTING OF SPECIMENS FROM CAPSULE U 5.1 OVERVIEW The post-irradiation mechanical testing of the Charpy V-notch impact specimens and tensile specimens was performed at the Westinghouse Churchill Laboratory Services Hot Cell Facility. Testing was performed in accordance with 10 CFR 50, Appendix H [Ref. 7] and ASTM Specification E185-82 [Ref. 8].

Capsule U was opened upon receipt at the hot cell laboratory. The specimens and spacer blocks were carefully removed, inspected for identification number, and checked against the master list in WCAP-9455

[Ref. 2]. All of the items were in their proper locations.

Examination of the thermal monitors indicated that the three temperature monitors had not melted. Based on this examination, the maximum temperature to which the specimens were exposed was less than 579°F (304°C).

The Charpy impact tests were performed per ASTM Specification E185-82 [Ref. 8] and E23-18 [Ref. 9]

on a Tinius-Olsen Model 74, 358J machine. The Charpy machine striker was instrumented with an Instron1 Impulse system. Instrumented testing and calibration were performed to ASTM E2298-18

[Ref. 10].

The instrumented striker load signal data acquisition rate was 819 kHz with data acquired for 10 ms. From the load-time curve, the load of general yielding (Fgy), the maximum load (Fm) and the time to maximum load were determined. Under some test conditions, a sharp drop in load indicative of fast fracture was observed. The load at which fast fracture was initiated is identified as the brittle fracture initiation/load at initiation of unstable crack propagation (Fbf). The termination load after the fast load drop is identified as the arrest load/load at end of unstable crack propagation (Fa). Fgy, Fm, Fbf, and Fa were determined per the guidance in ASTM Standard E2298-18 [Ref. 10].

The pre-maximum load energy (Wm) was determined by integrating the load-time record to the maximum load point via the instrumented Charpy software. The integrated total impact energy (Wt) is compared to the absorbed energy measured from the dial energy (KV).

Percent shear was determined from post-fracture photographs using the ratio-of-areas method in compliance with ASTM E23-18 [Ref. 9] and A370-18 [Ref. 11]. The lateral expansion was measured using a dial gage rig similar to that shown in the same ASTM Standards.

1 Instron is a registered trademark of Instron Corporation.

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Westinghouse Non-Proprietary Class 3 5-2 Tensile tests were performed on a 250 kN Instron screw driven tensile machine (Model 5985) per ASTM E185-82 [Ref. 8]. Testing met ASTM Specifications E8/E8M-16 [Ref. 12] for room temperature or E21-17

[Ref. 13] for elevated temperatures.

The tensile specimens were, nominally, 4.23 inches long with a 1.00 inch gage length and 0.250 inch in diameter, per WCAP-9455 [Ref. 2]. Strain measurements were made using an extensometer, which was attached to the 1.00 inch gage section of the tensile specimen. The strain rate obtained met the requirement of ASTM E8/E8M-16 [Ref. 12] and ASTM E21-17 [Ref. 13].

Elevated test temperatures were obtained with a three-zone electric resistance split-tube Instron SF-16 furnace with an 11-inch hot zone. For the elevated tests, temperature was measured by two Type N thermocouples in contact with the gage section of the specimen per ASTM E21-17 [Ref. 13]. Tensile specimens were soaked at temperature (+/- 5ºF) for a minimum of 20 minutes before testing. All tests were conducted in air.

The yield load, ultimate load, fracture load, uniform elongation, and elongation at fracture were determined directly from the load-extension curve. The yield strength (0.2% offset method), ultimate tensile strength, and fracture strength were calculated using the original cross-sectional area. Yield point elongation (YPE) was calculated as the difference in strain between the upper yield strength and the onset of uniform strain hardening using the methodology described in ASTM E8/E8M-16 [Ref. 12]. The final diameter and final gage length were determined from post-fracture photographs. This final diameter measurement was used to calculate the fracture stress (fracture true stress) and the percent reduction in area. The reported total elongation is the elongation at fracture.

5.2 CHARPY V-NOTCH IMPACT TEST RESULTS The results of the Charpy V-notch impact tests performed on the various materials contained in Capsule U, which received a fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) in 2.0 EFPY of operation, are presented in Tables 5-1 through 5-8 and are compared with the unirradiated results as shown in Figures 5-1 through 5-12. The unirradiated capsule results were taken from WCAP-9455 [Ref. 2]. The original program unirradiated material input data, were updated using CVGRAPH, Version 6.02.

The transition temperature increases and decreases in upper-shelf energies for the Capsule U materials are summarized in Table 5-9 and led to the following results:

Irradiation of the reactor vessel Intermediate Shell Forging 05 Charpy specimens, oriented with the tangential axis of the specimen parallel to the major rolling direction (tangential orientation), resulted in an irradiated 30 ft-lb transition temperature (T30) of -15.6F and an irradiated 50 ft-lb transition temperature (T50) of 12.7°F. This results in a 30 ft-lb transition temperature increase of 26.7F (T30 =

26.7F) and a 50 ft-lb transition temperature increase of 33.6F (T50 = 33.6F) for the tangentially oriented specimens.

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Westinghouse Non-Proprietary Class 3 5-3 Irradiation of the reactor vessel Intermediate Shell Forging 05 Charpy specimens, oriented with the tangential axis of the specimen perpendicular to the major rolling direction (axial orientation), resulted in an irradiated 30 ft-lb transition temperature (T30) of -20.5F and an irradiated 50 ft-lb transition temperature (T50) of 24.2F. This results in a 30 ft-lb transition temperature increase of 21.3F (T30 =

21.3F) and a 50 ft-lb transition temperature increase of 18.1F (T50 = 18.1F) for the axially oriented specimens.

Irradiation of the Surveillance Program Weld Material (Heat # 895075) Charpy specimens resulted in an irradiated 30 ft-lb transition temperature (T30) of -25.1F and an irradiated 50 ft-lb transition temperature (T50) of 14.3F. This results in a 30 ft-lb transition temperature increase of 32.6F (T30

= 32.6F) and a 50 ft-lb transition temperature increase of 33.5F (T30 = 33.5F).

Irradiation of the HAZ Material Charpy specimens resulted in an irradiated 30 ft-lb transition temperature (T30) of -103.4F and an irradiated 50 ft-lb transition temperature (T50) of -61.7F. This results in a 30 ft-lb transition temperature reduction of 1.6F (T30 = -1.6F) and a 50 ft-lb transition temperature increase of 19.8F (T50 = 19.8F). Note that physically, a reduction in T30 (T30 = -1.6F) should not occur. However, this can be indicated due to the standard error of the measurements and/or variation of material properties within a sample/heat. When this measured reduction is observed, all downstream analyses which use the results should conservatively assume that no shift in T30 has occurred, i.e., T30 = 0F.

The average upper-shelf energy of Intermediate Shell Forging 05 (tangential orientation) resulted in an average energy decrease of -45 ft-lb after irradiation. This decrease results in an irradiated average upper-shelf energy of 130 ft-lb for the tangentially oriented specimens.

The average upper-shelf energy of Intermediate Shell Forging 05 (axial orientation) resulted in an average energy decrease of -5 ft-lb after irradiation. This decrease results in an irradiated average upper-shelf energy of 105 ft-lb for the axially oriented specimens.

The average upper-shelf energy of the Surveillance Program Weld Material (Heat # 895075) Charpy specimens resulted in an average energy decrease of -9 ft-lb after irradiation. This decrease results in an irradiated average upper-shelf energy of 135 ft-lb for the weld metal specimens.

The average upper-shelf energy of the HAZ Material Charpy specimens resulted in an average energy decrease of -12 ft-lb after irradiation. This decrease results in an irradiated average upper-shelf energy of 118 ft-lb for the HAZ Material.

Comparisons of the measured 30 ft-lb shift in transition temperature values and upper-shelf energy decreases to those predicted by Regulatory Guide 1.99, Revision 2 [Ref. 1] for the Watts Bar Unit 2 reactor vessel surveillance materials are presented in Table 5-10.

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Westinghouse Non-Proprietary Class 3 5-4 The fracture appearance of each irradiated Charpy specimen from the various materials is shown in Figures 5-13 through 5-16. The fractures show an increasingly ductile or tougher appearance with increasing test temperature. Load-time records for the individual instrumented Charpy specimens are contained in Appendix B.

5.3 TENSILE TEST RESULTS The results of the tensile tests performed on the various materials contained in Capsule U irradiated to 6.04 x 1018 n/cm2 (E > 1.0 MeV) are presented in Table 5-11 and are compared with unirradiated results as shown in Figure 5-17 through Figure 5-19.

The results of the tensile tests performed on the Intermediate Shell Forging 05 (tangential orientation) indicated that irradiation to 6.04 x 1018 n/cm2 (E > 1.0 MeV) caused increases in the 0.2 percent offset yield strength and the ultimate tensile strength when compared to unirradiated data in WCAP-9455 [Ref. 2]. See Figure 5-17.

The results of the tensile tests performed on the Intermediate Shell Forging 05 (axial orientation) indicated that irradiation to 6.04 x 1018 n/cm2 (E > 1.0 MeV) caused increases in the 0.2 percent offset yield strength and the ultimate tensile strength when compared to unirradiated data in WCAP-9455 [Ref. 2]. See Figure 5-18.

The results of the tensile tests performed on the Surveillance Program Weld Material (Heat # 895075) indicated that irradiation to 6.04 x 1018 n/cm2 (E > 1.0 MeV) caused increases in the 0.2 percent offset yield strength and the ultimate tensile strength when compared to unirradiated data [Ref. 2]. See Figure 5-19.

The fractured tensile specimens for the Intermediate Shell Forging 05 (tangential orientation) material are shown in Figure 5-20; the fractured tensile specimens for the Intermediate Shell Forging 05 (axial orientation) are shown in Figure 5-21; and the fracture tensile specimens for the Surveillance Program Weld Material (Heat # 895075) are shown in Figure 5-22. The engineering stress-strain curves for the tensile tests are shown in Figure 5-23 through Figure 5-31.

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Westinghouse Non-Proprietary Class 3 5-5 Table 5-1 Charpy V-notch Data for the Watts Bar Unit 2 Intermediate Shell Forging 05 Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) (Tangential Orientation)

Sample Temperature Impact Energy Lateral Expansion Shear Number °F °C ft-lbs Joules mils mm  %

BL10 -60 -51 8 11 6 0.2 5 BL4 -50 -46 21 28 14 0.4 10 BL8 -30 -34 32 43 22 0.6 10 BL15 -20 -29 21 28 18 0.5 10 BL6 -15 -26 28 38 21 0.5 15 BL3 -10 -23 26 35 19 0.5 15 BL5 -5 -21 42 57 33 0.8 20 BL11 0 -18 48 65 34 0.9 25 BL1 10 -12 52 71 39 1.0 25 BL9 40 4 57 77 42 1.1 35 BL13 75 24 106 144 75 1.9 70 BL2 120 49 124 168 86 2.2 100 BL7 170 77 130 176 83 2.1 100 BL14 200 93 138 187 90 2.3 100 BL12 220 104 130 176 85 2.2 100 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-6 Table 5-2 Charpy V-notch Data for the Watts Bar Unit 2 Intermediate Shell Forging 05 Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) (Axial Orientation)

Sample Temperature Impact Energy Lateral Expansion Shear Number °F °C ft-lbs Joules mils mm  %

BT1 -60 -51 14 19 9 0.2 10 BT9 -50 -46 22 30 14 0.4 15 BT2 -35 -37 10 14 10 0.3 10 BT6 -30 -34 31 42 22 0.6 15 BT4 -20 -29 39 53 28 0.7 15 BT15 -15 -26 29 39 21 0.5 15 BT10 -10 -23 27 37 21 0.5 15 BT8 0 -18 41 56 29 0.7 15 BT3 10 -12 49 66 39 1.0 20 BT12 30 -1 61 83 49 1.2 35 BT14 75 24 73 99 54 1.4 55 BT13 120 49 74 100 58 1.5 60 BT5 170 77 102 138 73 1.9 100 BT11 200 93 109 148 76 1.9 100 BT7 220 104 103 140 80 2.0 100 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-7 Table 5-3 Charpy V-notch Data for the Watts Bar Unit 2 Surveillance Program Weld Material (Heat # 895075) Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV)

Sample Temperature Impact Energy Lateral Expansion Shear Number °F °C ft-lbs Joules mils mm  %

BW13 -60 -51 21 28 17 0.4 25 BW8 -50 -46 20 27 16 0.4 20 BW15 -30 -34 21 28 17 0.4 35 BW7 -25 -32 23 31 21 0.5 30 BW4 -20 -29 26 35 23 0.6 30 BW14 -15 -26 50 68 38 1.0 45 BW9 -10 -23 39 53 28 0.7 40 BW1 0 -18 38 52 29 0.7 35 BW12 10 -12 52 71 42 1.1 40 BW3 60 16 68 92 52 1.3 55 BW6 75 24 110 149 76 1.9 80 BW2 120 49 86 117 71 1.8 60 BW5 170 77 123 167 84 2.1 100 BW10 200 93 138 187 90 2.3 100 BW11 220 104 143 194 86 2.2 100 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-8 Table 5-4 Charpy V-notch Data for the Watts Bar Unit 2 Heat-Affected Zone (HAZ) Material Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV)

Sample Temperature Impact Energy Lateral Expansion Shear Number °F °C ft-lbs Joules mils mm  %

BH5 -115 -82 29 39 16 0.4 25 BH3 -110 -79 42 57 23 0.6 25 BH10 -100 -73 14 19 7 0.2 20 BH2 -90 -68 39 53 23 0.6 25 BH12 -80 -62 33 45 22 0.6 35 BH7 -70 -57 63 85 37 0.9 55 BH15 -60 -51 52 71 31 0.8 45 BH14 -35 -37 77 104 48 1.2 60 BH8 -30 -34 33 45 25 0.6 45 BH11 -20 -29 71 96 42 1.1 60 BH1 10 -12 98 133 56 1.4 75 BH4 75 24 117 159 68 1.7 100 BH13 150 66 105 142 74 1.9 100 BH6 200 93 125 169 73 1.9 100 BH9 220 104 127 172 73 1.9 100 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-9 Table 5-5 Instrumented Charpy Impact Test Results for the Watts Bar Unit 2 Intermediate Shell Forging 05 Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) (Tangential Orientation)

Total Energy to Total Dial General Test Instrumented Difference, Max Maximum Time to Fracture Arrest Sample Energy, Yield Temp Energy, (KV-Wt)/KV Load, Load, Fm Fm Load, Fbf Load, Fa Number KV Load, Fgy

(°F) Wt (%) Wm (lb) (msec) (lb) (lb)

(ft-lb) (lb)

(ft-lb) (ft-lb)

BL10 -60 7.5 7.43 1% 3.53 4000 0.09 3400 3400 0 BL4 -50 20.5 19.69 4% 3.40 4000 0.09 3200 4000 0 BL8 -30 31.5 29.43 7% 28.27 4100 0.51 3200 4100 0 BL15 -20 20.5 19.23 6% 16.24 4000 0.31 3100 3800 0 BL6 -15 28.25 27.00 4% 23.49 4000 0.43 3200 3900 0 BL3 -10 26.25 24.73 6% 23.33 4000 0.44 3100 4000 0 BL5 -5 42.25 39.81 6% 34.04 4200 0.6 3200 3900 0 BL11 0 47.5 43.09 9% 34.71 4200 0.63 3200 3800 0 BL1 10 52 48.59 7% 33.53 4100 0.61 3000 3900 0 BL9 40 56.5 49.42 13% 32.8 4100 0.6 3000 3900 0 BL13 75 105.5 93.06 12% 32.35 4000 0.6 2900 2300 800 BL2 120 124 114.35 8% 31.08 3900 0.6 2700 0 0 BL7 170 129.75 119.56 8% 30.42 3900 0.61 2600 0 0 BL14 200 137.5 127.37 7% 29.79 3800 0.6 2400 0 0 BL12 220 130 119.59 8% 29.73 3800 0.61 2500 0 0 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-10 Table 5-6 Instrumented Charpy Impact Test Results for the Watts Bar Unit 2 Intermediate Shell Forging 05 Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV) (Axial Orientation)

Total Energy to Total Dial General Test Instrumented Difference, Max Maximum Time to Fracture Arrest Sample Energy, Yield Temp Energy, (KV-Wt)/KV Load, Load, Fm Fm Load, Fbf Load, Fa Number KV Load, Fgy

(°F) Wt (%) Wm (lb) (msec) (lb) (lb)

(ft-lb) (lb)

(ft-lb) (ft-lb)

BT1 -60 14 13.34 5% 3.23 4000 0.09 3300 3800 0 BT9 -50 22 21.29 3% 19.5 4100 0.36 3200 3700 0 BT2 -35 10 9.69 3% 3.4 4000 0.09 3300 3800 0 BT6 -30 31 29.14 6% 28.34 4100 0.5 3100 4000 0 BT4 -20 38.5 36.24 6% 34.27 4100 0.61 3200 4000 0 BT15 -15 29.25 28.24 3% 19.05 4000 0.36 3100 3900 0 BT10 -10 27 25.02 7% 23.36 4000 0.43 3100 3800 0 BT8 0 41 38.46 6% 33.72 4100 0.6 3100 4000 0 BT3 10 49 45.29 8% 33.36 4100 0.6 3000 3900 0 BT12 30 61.25 56.00 9% 33.63 4200 0.6 3000 3800 300 BT14 75 73 61.86 15% 32.23 4000 0.6 2900 3200 1000 BT13 120 74.25 62.98 15% 30.71 3900 0.61 2700 3000 1400 BT5 170 102 94.57 7% 30.29 3900 0.61 2200 0 0 BT11 200 108.5 100.54 7% 31.38 3800 0.62 2500 0 0 BT7 220 103 95.27 8% 28.95 3800 0.6 2500 0 0 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-11 Table 5-7 Instrumented Charpy Impact Test Results for the Watts Bar Unit 2 Surveillance Program Weld Material (Heat # 895075)

Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV)

Total Energy to Total Dial General Arrest Test Instrumented Difference, Max Maximum Time to Fracture Sample Energy, Yield Load, Temp Energy, (KV-Wt)/KV Load, Load, Fm Fm Load, Fbf Number KV Load, Fgy Fa

(°F) Wt (%) Wm (lb) (msec) (lb)

(ft-lb) (lb) (lb)

(ft-lb) (ft-lb)

BW13 -60 20.5 17.62 14% 3.5 4100 0.09 3200 3900 800 BW8 -50 19.5 17.77 9% 3.21 3900 0.09 3100 3500 0 BW15 -30 20.5 16.63 19%* 3.24* 3900* 0.09* 3100* 3600* 800*

BW7 -25 22.5 20.27 10% 3.4 3800 0.09 3100 3800 1400 BW4 -20 26 24.63 5% 3.2 3900 0.09 3000 3700 500 BW14 -15 50 45.66 9% 33.33 4000 0.6 3100 3700 2100 BW9 -10 38.5 34.85 9% 28.03 3900 0.51 3200 3900 1600 BW1 0 37.5 35.35 6% 27.91 4000 0.5 3100 3700 1400 BW12 10 52 47.42 9% 32.81 4000 0.61 3000 3800 1600 BW3 60 68 61.59 9% 13.71 4000 0.6 2800 3600 1400 BW6 75 109.5 100.56 8% 32.02 4000 0.6 2800 3000 2800 BW2 120 86.25 79.06 8% 31.19 3900 0.6 2800 2700 1500 BW5 170 123 113.84 7% 51.15 3700 0.99 2600 0 0 BW10 200 138 128.24 7% 48.83 3700 0.95 2500 0 0 BW11 220 143 131.6 8% 47.95 3700 0.95 2200 0 0

  • The difference between instrumented Charpy and dial values was greater than 15%, but the values were not adjusted as required by E2298-18 [Ref. 10].

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Westinghouse Non-Proprietary Class 3 5-12 Table 5-8 Instrumented Charpy Impact Test Results for the Watts Bar Unit 2 Heat-Affected Zone (HAZ) Material Irradiated to a Fluence of 6.04 x 1018 n/cm2 (E > 1.0 MeV)

Total Energy to Total Dial General Arrest Test Instrumented Difference, Max Maximum Time to Fracture Sample Energy, Yield Load, Temp Energy, (KV-Wt)/KV Load, Load, Fm Fm Load, Fbf Number KV Load, Fgy Fa

(°F) Wt (%) Wm (lb) (msec) (lb)

(ft-lb) (lb) (lb)

(ft-lb) (ft-lb)

BH5 -115 28.5 25.53 10% 4.63 4300 0.12 3500 4100 0 BH3 -110 41.75 38.45 8% 37.53 4400 0.62 3700 4400 0 BH10 -100 13.5 12.4 8% 3.57 4400 0.1 3400 3500 0 BH2 -90 38.5 36.1 6% 3.44 4300 0.09 3400 4200 0 BH12 -80 33 28.22 14% 3.57 4300 0.1 3500 4100 900 BH7 -70 62.5 52.99 15% 35.93 4300 0.61 3400 3900 900 BH15 -60 52 44.08 15% 35.91 4300 0.6 3300 4000 600 BH14 -35 76.5 68.28 11% 35.41 4300 0.6 3400 4100 1600 BH8 -30 32.5 26.61* 18%* 3.46* 4000* 0.09* 3200* 3600* 1700*

BH11 -20 71 62.25 12% 34.87 4200 0.6 3200 3800 1600 BH1 10 98 91.49 7% 34.13 4200 0.61 3000 3600 1900 BH4 75 116.5 109.21 6% 53.54 4100 0.95 3000 0 0 BH13 150 104.5 97.83 6% 30.99 3900 0.6 2700 0 0 BH6 200 124.5 116.79 6% 41.01 4000 0.79 2800 0 0 BH9 220 127 117.92 7% 49.78 3800 0.95 2500 0 0

  • The difference between instrumented Charpy and dial values was greater than 15%, but the values were not adjusted as required by E2298-18 [Ref. 10].

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Westinghouse Non-Proprietary Class 3 5-13 Table 5-9 Effect of Irradiation to 6.04 x 1018 n/cm2 (E > 1.0 MeV) on the Charpy V-Notch Toughness Properties of the Watts Bar Unit 2 Reactor Vessel Surveillance Capsule U Materials Average 30 ft-lb Transition Average 35 mil Lateral Expansion Average 50 ft-lb Transition Average Energy Absorption Material Temperature(a) (°F) Temperature(a) (°F) Temperature(a) (°F) > 95% Shear(b) (ft-lb)

Unirradiated Irradiated T Unirradiated Irradiated T Unirradiated Irradiated T Unirradiated Irradiated E Intermediate Shell Forging 05 -42.3 -15.6 26.7 -20.7 9.1 29.8 -20.9 12.7 33.6 175 130 -45 (Tangential)

Intermediate Shell

-41.8 -20.5 21.3 1.3 15.0 13.7 6.1 24.2 18.1 110 105 -5 Forging 05 (Axial)

Surveillance Weld Material -57.7 -25.1 32.6 -24.7 3.7 28.4 -19.2 14.3 33.5 144 135 -9 (Heat # 895075)

Heat-Affected Zone

-101.8 -103.4 -1.6(c) -69.7 -46.1 23.6 -81.5 -61.7 19.8 130 118 -12 (HAZ) Material Notes:

(a) Average value is determined by CVGRAPH, Version 6.02 (see Appendix C).

(b) Upper-shelf Energy (USE) values are a calculated average from unirradiated and Capsule U Charpy test results for specimens that achieved greater than or equal to 95% shear.

(c) Note that physically a reduction in T30 should not occur.

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Westinghouse Non-Proprietary Class 3 5-14 Table 5-10 Comparison of the Watts Bar Unit 2 Surveillance Material 30 ft-lb Transition Temperature Shifts and Upper-Shelf Energy Decreases with Regulatory Guide 1.99, Revision 2, Predictions Capsule 30 ft-lb Transition Upper-Shelf Energy Fluence Temperature Shift Decrease Material Capsule (x 1019 n/cm2, Predicted(a) Measured(b) Predicted(a) Measured(b)

E > 1.0 MeV) (°F) (°F) (%) (%)

Intermediate Shell Forging 05 U 0.604 26.6 26.7 17 26 (Tangential)

Intermediate Shell Forging 05 U 0.604 26.6 21.3 17 5 (Axial)

Surveillance Weld Material U 0.604 38.6 32.6 17 6 (Heat # 895075)

Heat-Affected Zone Material U 0.604 --- -1.6 --- 9 Notes:

(a) Based on Regulatory Guide 1.99, Revision 2 [Ref. 1], methodology using the capsule fluence and best-estimate weight percent values of copper and nickel of the surveillance material.

(b) Calculated by CVGRAPH, Version 6.02 using measured Charpy data (See Appendix C).

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Westinghouse Non-Proprietary Class 3 5-15 Table 5-11 Tensile Properties of the Watts Bar Unit 2 Capsule U Reactor Vessel Surveillance Materials Irradiated to 6.04 x 1018 n/cm2 (E > 1.0 MeV) 0.2% Fracture Test Ultimate Fracture Fracture Uniform Total Reduction Sample Yield True Material Temp. Strength Load Strength Elongation Elongation in Area Number Strength Stress

(°F) (ksi) (kip) (ksi) (%) (%) (%)

(ksi) (ksi)

BL1 78 63.0 86.5 2.51 51.1 201 12.6 31.9 75 Intermediate Shell Forging 05 BL2 300 58.8 80.4 2.54 51.7 217 10.6 24.7 76 (Tangential)

BL3 550 57.3 86.2 2.76 56.3 190 9.1 22.9 70 70 BT1 78 66.8 89.7 2.99 60.8 200 11.3 25.2 Intermediate Shell 70 Forging 05 BT2 300 61.8 83.0 2.91 59.4 195 10.2 22.2 (Axial)

BT3 550 60.4 87.1 3.08 62.7 179 9.9 21.3 65 BW1 78 74.5 88.2 2.57 52.3 227 12.8 30.2 77 Surveillance Weld Material BW2 300 70.2 81.1 2.40 48.9 199 11.6 26.9 75 (Heat # 895075)

BW3 550 64.1 83.4 2.57 52.4 188 6.5 19.7 72 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-16 Figure 5-1 Charpy V-Notch Impact Energy vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation)

Note: Data for Capsule U was taken from Table 5-1.

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Westinghouse Non-Proprietary Class 3 5-17 Figure 5-2 Charpy V-Notch Lateral Expansion vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation)

Note: Data for Capsule U was taken from Table 5-1.

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Westinghouse Non-Proprietary Class 3 5-18 Figure 5-3 Charpy V-Notch Percent Shear vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation)

Note: Data for Capsule U was taken from Table 5-1.

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Westinghouse Non-Proprietary Class 3 5-19

  • Legibility for this test temperature is not clear. It could be 0°F rather than the -100°F shown in this plot.

Using -100°F is consistent with WCAP-9455, Rev. 4 and conservative, providing a larger T30 shift. This may be revisited, if necessary, during a future evaluation, e.g. next tested capsules credibility evaluation.

Figure 5-4 Charpy V-Notch Impact Energy vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation)

Note: Data for Capsule U was taken from Table 5-2.

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Westinghouse Non-Proprietary Class 3 5-20

  • Legibility for this test temperature is not clear. It could be 0°F rather than the -100°F shown in this plot.

Using -100°F is consistent with WCAP-9455, Rev. 4 and conservative, providing a larger T30 shift. This may be revisited, if necessary, during a future evaluation, e.g. next tested capsules credibility evaluation.

Figure 5-5 Charpy V-Notch Lateral Expansion vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation)

Note: Data for Capsule U was taken from Table 5-2.

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Westinghouse Non-Proprietary Class 3 5-21

  • Legibility for this test temperature is not clear. It could be 0°F rather than the -100°F shown in this plot.

Using -100°F is consistent with WCAP-9455, Rev. 4 and conservative, providing a larger T30 shift. This may be revisited, if necessary, during a future evaluation, e.g. next tested capsules credibility evaluation.

Figure 5-6 Charpy V-Notch Percent Shear vs. Temperature for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation)

Note: Data for Capsule U was taken from Table 5-2.

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Westinghouse Non-Proprietary Class 3 5-22 Figure 5-7 Charpy V-Notch Impact Energy vs. Temperature for Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075)

Note: Data for Capsule U was taken from Table 5-3.

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Westinghouse Non-Proprietary Class 3 5-23 Figure 5-8 Charpy V-Notch Lateral Expansion vs. Temperature for Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075)

Note: Data for Capsule U was taken from Table 5-3.

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Westinghouse Non-Proprietary Class 3 5-24 Figure 5-9 Charpy V-Notch Percent Shear vs. Temperature for Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075)

Note: Data for Capsule U was taken from Table 5-3.

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Westinghouse Non-Proprietary Class 3 5-25 Figure 5-10 Charpy V-Notch Impact Energy vs. Temperature for Watts Bar Unit 2 Reactor Vessel Heat-Affected Zone Material Note: Data for Capsule U was taken from Table 5-4.

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Westinghouse Non-Proprietary Class 3 5-26 Figure 5-11 Charpy V-Notch Lateral Expansion vs. Temperature for Watts Bar Unit 2 Reactor Vessel Heat-Affected Zone Material Note: Data for Capsule U was taken from Table 5-4.

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Westinghouse Non-Proprietary Class 3 5-27 Figure 5-12 Charpy V-Notch Percent Shear vs. Temperature for Watts Bar Unit 2 Reactor Vessel Heat-Affected Zone Material Note: Data for Capsule U was taken from Table 5-4.

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Westinghouse Non-Proprietary Class 3 5-28 BL10, -60°F BL4, -50°F BL8, -30°F BL15, -20°F BL6, -15°F BL3, -10°F BL5, -5°F BL11, 0°F BL1, 10°F BL9, 40°F BL13, 75°F BL2, 120°F BL7, 170°F BL14, 200°F BL12, 220°F Figure 5-13 Charpy Impact Specimen Fracture Surfaces for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation)

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Westinghouse Non-Proprietary Class 3 5-29 BT1, -60°F BT9, -50°F BT2, -35°F BT6, -30°F BT4, -20°F BT15, -15°F BT10, -10°F BT8, 0°F BT3, 10°F BT12, 30°F BT14, 75°F BT13, 120°F BT5, 170°F BT11, 200°F BT7, 220°F Figure 5-14 Charpy Impact Specimen Fracture Surfaces for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation)

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Westinghouse Non-Proprietary Class 3 5-30 BW13, -60°F BW8, -50°F BW15, -30°F BW7, -25°F BW4, -20°F BW14, -15°F BW9, -10°F BW1, 0°F BW12, 10°F BW3, 60°F BW6, 75°F BW2, 120°F BW5, 170°F BW10 200°F BW11, 220°F Figure 5-15 Charpy Impact Specimen Fracture Surfaces for the Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075)

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Westinghouse Non-Proprietary Class 3 5-31 BH5, -115°F BH3, -110°F BH10, -100°F BH2, -90°F BH12, -80°F BH7, -70°F BH15, -60°F BH14, -35°F BH8, -30°F BH11, -20°F BH1, 10°F BH4, 75°F BH13, 150°F BH6, 200°F BH9, 220°F Figure 5-16 Charpy Impact Specimen Fracture Surfaces for the Watts Bar Unit 2 Reactor Vessel Heat-Affected Zone Material WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-32 Legend:, , and are unirradiated

, , and are irradiated to 6.04 x 1018 n/cm2 (E > 1.0 MeV)

Figure 5-17 Tensile Properties for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation)

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Westinghouse Non-Proprietary Class 3 5-33 Legend:, , and are unirradiated

, , and are irradiated to 6.04 x 1018 n/cm2 (E > 1.0 MeV)

Figure 5-18 Tensile Properties for Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation)

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Westinghouse Non-Proprietary Class 3 5-34 Legend:, , and are unirradiated

, , and are irradiated to 6.04 x 1018 n/cm2 (E > 1.0 MeV) 80 70 Area Reduction 60 50 Ductility (% )

40 30 Total Elongation 20 10 Uniform Elongation 0

0 100 200 300 400 500 600 Temperature (°F)

Figure 5-19 Tensile Properties for Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075)

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Westinghouse Non-Proprietary Class 3 5-35 BL1 tested at 78°F BL2 tested at 300°F BL3 tested at 550°F Figure 5-20 Fractured Tensile Specimens from Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Tangential Orientation) [Scale in 1/10th of inch]

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Westinghouse Non-Proprietary Class 3 5-36 BT1 tested at 78°F BT2 tested at 300°F BT3 tested at 550°F Figure 5-21 Fractured Tensile Specimens from Watts Bar Unit 2 Reactor Vessel Intermediate Shell Forging 05 (Axial Orientation) [Scale in 1/10th of inch]

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Westinghouse Non-Proprietary Class 3 5-37 BW1 tested at 78°F BW2 tested at 300°F BW3 tested at 550°F Figure 5-22 Fractured Tensile Specimens from Watts Bar Unit 2 Reactor Vessel Surveillance Program Weld Material (Heat # 895075) [Scale in 1/10th of inch]

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Westinghouse Non-Proprietary Class 3 5-38 Figure 5-23 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BL1, Tested at 78°F Figure 5-24 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BL2, Tested at 300°F Figure 5-25 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BL3, Tested at 550°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-39 Figure 5-26 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BT1, Tested at 78°F Figure 5-27 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BT2, Tested at 300°F Figure 5-28 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BT3, Tested at 550°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 5-40 Figure 5-29 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BW1, Tested at 78°F Figure 5-30 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BW2, Tested at 300°F Figure 5-31 Engineering Stress-Strain Curve for Watts Bar Unit 2, Capsule U, Tensile Specimen BW3, Tested at 550°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 6-1 6 RADIATION ANALYSIS AND NEUTRON DOSIMETRY

6.1 INTRODUCTION

This section describes a discrete ordinates (Sn) transport analysis performed for the Watts Bar Unit 2 reactor to determine the neutron radiation environment within the reactor pressure vessel and surveillance capsules.

In this analysis, fast neutron exposure parameters in terms of fast neutron (E > 1.0 MeV) fluence and iron atom displacements (dpa) were established on a plant- and fuel-cycle-specific basis. An evaluation of the most recent dosimetry sensor set from Capsule U, withdrawn at the end of the 2nd plant operating cycle, is provided. Comparisons of the results from the dosimetry evaluations with the analytical predictions served to validate the plant-specific neutron transport calculations. These validated calculations subsequently form the basis for projections of the neutron exposure of the reactor pressure vessel for operating periods extending to 36 effective full-power years (EFPY).

The use of fast neutron (E > 1.0 MeV) fluence to correlate measured material property changes to the neutron exposure of the material has traditionally been accepted for the development of damage trend curves as well as for the implementation of trend curve data to assess the condition of the vessel. However, it has been suggested that an exposure model that accounts for differences in neutron energy spectra between surveillance capsule locations and positions within the vessel wall could lead to an improvement in the uncertainties associated with damage trend curves and improved accuracy in the evaluation of damage gradients through the reactor vessel wall.

Because of this potential shift away from a threshold fluence toward an energy-dependent damage function for data correlation, ASTM Standard Practice E853-18, Standard Practice for Analysis and Interpretation of Light-Water Reactor Surveillance Results, [Ref. 14] recommends reporting displacements per iron atom along with fluence (E > 1.0 MeV) to provide a database for future reference. The energy-dependent dpa function to be used for this evaluation is specified in ASTM Standard Practice E693-94, Standard Practice for Characterizing Neutron Exposures in Iron and Low Alloy Steels in Terms of Displacements per Atom

[Ref. 15]. The application of the dpa parameter to the assessment of embrittlement gradients through the thickness of the reactor vessel wall has been promulgated in Revision 2 to Regulatory Guide 1.99, Radiation Embrittlement of Reactor Vessel Materials [Ref. 1].

All of the calculations and dosimetry evaluations described in this section and in Appendix A were based on nuclear cross-section data derived from ENDF/B-VI. Furthermore, the neutron transport and dosimetry evaluation methodologies follow the guidance of Regulatory Guide 1.190, Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence [Ref. 16]. Additionally, the methods used to develop the calculated pressure vessel fluence are consistent with the NRC-approved methodology described in WCAP-18124-NP-A, Fluence Determination with RAPTOR-M3G and FERRET [Ref. 17].

6.2 DISCRETE ORDINATES ANALYSIS The arrangement of the surveillance capsules in the Watts Bar Unit 2 reactor vessel is shown in Figure 4-1.

Six irradiation capsules attached to the neutron pad are included in the reactor design that constitutes the reactor vessel surveillance program. Capsules U, X, V, Y, W, and Z are located at azimuthal angles of 56.0°,

236.0°, 58.5°, 238.5°, 124.0°, and 304.0°, respectively. These full-core positions correspond to the following octant symmetric locations represented in Figure 6-1 through Figure 6-3: 34.0° from the core WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 6-2 cardinal axes (for the 56.0° and 236.0° dual surveillance capsule holder locations found in octants with a 20.0° neutron pad segment); 31.5° from the core cardinal axes (for the 58.5° and 238.5° dual surveillance capsule holder locations found in octants with a 20.0° neutron pad segment); and 34.0° from the core cardinal axes (for the 304.0° and the 124.0° single surveillance capsule holder locations found in octants with a 17.5° neutron pad segment). The stainless steel specimen containers are 1.182-inch by 1-inch and are approximately 56 inches in height. The containers are positioned axially such that the test specimens are centered on the core midplane, thus spanning the central 5 feet of the 12-foot high reactor core.

From a neutronic standpoint, the surveillance capsules and associated support structures are significant. The presence of these materials has a significant effect on both the spatial distribution of neutron exposure rate and the neutron spectrum in the vicinity of the capsules. However, the capsules are far enough apart that they do not interfere with one another. In order to determine the neutron environment at the test specimen location, the capsules themselves must be included in the analytical model.

In performing the fast neutron exposure evaluations for the Watts Bar Unit 2 reactor vessel and surveillance capsules, plant-specific 3D forward transport calculations were carried out to directly solve for the space-and energy-dependent neutron exposure rate, (r,,z,E).

For the Watts Bar Unit 2 transport calculations, the models depicted in Figure 6-1 through Figure 6-3 were utilized. The reactor is octant symmetric with three different neutron pad and surveillance capsule configurations: octants with 20.0° neutron pads and surveillance capules located at 31.5° and 34°, octants with 17.5° neutron pads and a single surveillance capsule at 34.0°, and octants with 15.0° neutron pads and without surveillance capsules.

Each octant model contained a representation of the reactor core, the reactor internals, the pressure vessel cladding and vessel wall, the insulation external to the pressure vessel, and the primary biological shield wall. These models formed the basis for the calculated results and enabled making comparisons to the surveillance capsule dosimetry evaluations. In developing these analytical models, nominal design dimensions were generally employed for the various structural components. In addition, water temperatures, and hence, coolant densities in the reactor core and downcomer regions of the reactor were taken to be representative of full-power operating conditions. The coolant densities were treated on a fuel-cycle-specific basis. The reactor core itself was treated as a homogeneous mixture of fuel, cladding, water, and miscellaneous core structures such as fuel assembly grids, guide tubes, et cetera.

A section view of the RAPTOR-M3G model of the Watts Bar Unit 2 reactor is shown in Figure 6-4. The model extended radially from the centerline of the reactor core out to a location interior to the primary biological shield and over an axial span from an elevation approximately eight feet below the active fuel to five feet above the active fuel.

Each of the three RAPTOR-M3G models consisted of 200 radial mesh, 132 azimuthal mesh, and 347 vertical mesh. Mesh sizes were chosen to assure that proper convergence of the inner iterations was achieved on a pointwise basis. The pointwise inner iteration flux convergence criterion utilized in the RAPTOR-M3G calculations was set at a value of 0.001.

The core power distributions used in the plant-specific transport analysis for the first 2 fuel cycles at Watts Bar Unit 2 included cycle-dependent fuel assembly initial enrichments, burnups, and axial power WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 6-3 distributions. Actual operating characteristics through Cycle 2 have been evaluated; projections of future neutron exposure are based upon expected core loading patterns and operating characteristics for the following five fuel cycles. This information was used to develop spatial- and energy-dependent core source distributions averaged over each individual fuel cycle. Therefore, the results from the neutron transport calculations provided data in terms of fuel-cycle-averaged neutron exposure rate, which when multiplied by the appropriate fuel cycle length, generated the incremental fast neutron exposure for each fuel cycle. In constructing these core source distributions, the energy distribution of the source was based on an appropriate fission split for uranium and plutonium isotopes based on the initial enrichment and burnup history of individual fuel assemblies. From these assembly-dependent fission splits, composite values of energy release per fission, neutron yield per fission, and fission spectrum were determined.

All of the transport calculations supporting this analysis were carried out using the RAPTOR-M3G discrete ordinates code and the BUGLE-96 cross-section library, as described in [Ref. 17]. The BUGLE-96 library provides a coupled 47-neutron, 20-gamma-group cross-section data set produced specifically for light-water reactor (LWR) applications. In these analyses, anisotropic scattering was treated with a P3 Legendre expansion, and angular discretization was modeled with an S12 order of angular quadrature. Energy- and space-dependent core power distributions, as well as system operating temperatures, were treated on a fuel-cycle-specific basis.

Selected results from the neutron transport analyses are provided in Table 6-1 through Table 6-8. In Table 6-1, the calculated exposure rates expressed in terms of fast neutron (E > 1.0 MeV) fluence rate and iron atom displacement rate are given at the radial and azimuthal center of the surveillance capsule positions. Integrated neutron exposure levels are presented in Table 6-2 in terms of fast neutron (E >

1.0 MeV) fluence and Table 6-3 in terms of iron dpa. These results, representative of the average axial exposure of the material specimens, establish the calculated exposure of the surveillance capsules to date and projected into the future.

Neutron exposure data pertinent to selected pressure vessel materials are given in Table 6-4 and Table 6-5 for fast neutron (E > 1.0 MeV) fluence rate and fluence. Similar data are provided in Table 6-6 and Table 6-7 for dpa/s and dpa. The data presented represent the maximum neutron exposure experienced by the reactor pressure vessel (RPV) materials that will constitute inputs to the reactor vessel integrity analysis. The reported data considers both the inner and outer radius of the RPV base metal, and accounts for the possibility of higher neutron exposure values occurring on the outer surface of the RPV (as compared to the inner surface) for materials that are distant from the active core. In each case, the data are provided for each operating cycle of the Watts Bar Unit 2 reactor. Note that, for any given fuel cycle, the location of the maximum neutron exposure rate may or may not coincide with the location of the maximum neutron exposure.

These data tabulations include both plant- and fuel-cycle-specific calculated neutron exposures at the end of Cycle 2 and projections to 32 and 36 EFPY. Projections of neutron exposure beyond the end of Cycle 7 are based on the expected core loading pattern and operating characteristics of Cycle 7. The projections of future exposure account for an anticipated power uprate from 3411 MWt to 3459 MWt occurring at the beginning of Cycle 4, and the presence of Tritium-Producing Burnable Absorber Rods (TPBARs) in the fuel for Cycle 4 and beyond.

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Westinghouse Non-Proprietary Class 3 6-4 Updated lead factors for the Watts Bar Unit 2 surveillance capsules are provided in Table 6-8. The capsule lead factor is defined as the ratio of the calculated fluence (E > 1.0 MeV) at the geometric radial and azimuthal center of the surveillance capsule to the corresponding maximum calculated fluence at the pressure vessel clad/base metal interface.

6.3 NEUTRON DOSIMETRY The validity of the calculated neutron exposures previously reported in Section 6.2 is demonstrated by a direct comparison against the measured sensor reaction rates and a least-squares evaluation performed for each of the capsule dosimetry sets. However, since the neutron dosimetry measurement data merely serve to validate the calculated results, only the direct comparison of measured-to-calculated results for surveillance Capsule U is provided in this section of the report. For completeness, the assessment based on both direct and least-squares evaluation comparisons is documented in Appendix A.

The direct comparison of measured versus calculated fast neutron threshold reaction rates for the sensors from Capsule U, which was withdrawn from Watts Bar Unit 2 at the end of the 2nd fuel cycle, is summarized below.

Reaction Rate (rps/atom)

Reaction M/C Measured (M) Calculated (C)

Cu-63 (n,) Co-60 4.11E-17 4.52E-17 0.91 Fe-54 (n,p) Mn-54 5.24E-15 5.29E-15 0.99 Ni-58 (n,p) Co-58 7.21E-15 7.48E-15 0.96 U-238 (n,f) Cs-137 2.44E-14 2.98E-14 0.72 Np-237 (n,f) Cs-137 3.54E-13 3.07E-13 1.01 Average 0.92 Standard Deviation (%) 12.7 The measured-to-calculated (M/C) reaction rate ratios for the Capsule U threshold reactions range from 0.72 to 1.01, and the average M/C ratio is 0.92 12.7% (1). This direct comparison falls within the 20%

criterion specified in Regulatory Guide 1.190. This comparison validates the current analytical results described in Section 6.2; therefore, the calculations are deemed applicable for Watts Bar Unit 2.

6.4 CALCULATIONAL UNCERTAINTIES The uncertainty associated with the calculated neutron exposure of the Watts Bar Unit 2 surveillance capsule and reactor pressure vessel is based on the recommended approach provided in Regulatory Guide 1.190. In particular, the qualification of the methodology was carried out in the following four stages:

1. Simulator Benchmark Comparisons: Comparisons of calculations with measurements from simulator benchmarks, including the Pool Critical Assembly (PCA) simulator at the Oak Ridge National Laboratory (ORNL) and the VENUS-1 Experiment.

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Westinghouse Non-Proprietary Class 3 6-5

2. Operating Reactor and Calculational Benchmarks: Comparisons of calculations with surveillance capsule and reactor cavity measurements from the H.B. Robinson power reactor benchmark experiment. Also considered are comparisons of calculations performed with RAPTOR-M3G to results published in the NRC fluence calculation benchmark.
3. Analytic Uncertainty Analysis: An analytical sensitivity study addressing the uncertainty components resulting from important input parameters applicable to the plant-specific transport calculations used in the neutron exposure assessments.
4. Plant-Specific Benchmarking: Comparisons of the plant-specific calculations with all available dosimetry results from the Watts Bar Unit 2 surveillance program.

The first phase of the methods qualification (simulator benchmark comparisons) addressed the adequacy of basic transport calculation and dosimetry evaluation techniques and associated cross-sections. This phase, however, did not test the accuracy of commercial core neutron source calculations nor did it address uncertainties in operational or geometric variables that impact power reactor calculations. The second phase of the qualification (operating reactor and calculational benchmark comparisons) addressed uncertainties in these additional areas that are primarily methods-related and would tend to apply generically to all fast neutron exposure evaluations. The third phase of the qualification (analytical sensitivity study) identified the potential uncertainties introduced into the overall evaluation due to calculational methods approximations, as well as to a lack of knowledge relative to various plant-specific input parameters. The overall calculational uncertainty applicable to the Watts Bar Unit 2 analysis was established from results of these three phases of the methods qualification.

The fourth phase of the uncertainty assessment (comparisons with Watts Bar Unit 2 measurements) was used solely to demonstrate the validity of the transport calculations and to confirm the uncertainty estimates associated with the analytical results. The comparison was used only as a check and was not used in any way to modify the calculated surveillance capsule and pressure vessel neutron exposures previously described in Section 6.2. As such, the validation of the Watts Bar Unit 2 analytical model based on the measured plant dosimetry is completely described in Appendix A.

The following summarizes the uncertainties developed from the first three phases of the methodology qualification. Additional information pertinent to these evaluations is provided in Westinghouse Report WCAP-18124-NP-A, Fluence Determination with RAPTOR-M3G and FERRET [Ref. 17].

Description Capsule and Vessel IR Simulator Benchmark Comparisons 3%

H.B. Robinson Benchmark Comparisons 5%

Analytical Sensitivity Studies 11%

Additional Uncertainty for Factors not Explicitly Evaluated 5%

Net Calculational Uncertainty 13%

The net calculational uncertainty was determined by combining the individual components in quadrature.

Therefore, the resultant uncertainty was treated as random, and no systematic bias was applied to the WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 6-6 analytical results. The plant-specific measurement comparisons described in Appendix A support these uncertainty assessments for Watts Bar Unit 2.

The NRC-issued Safety Evaluation for WCAP-18124-NP appears in Section A of Ref. 17. The NRC identified two Limitations and Conditions associated with the application of RAPTOR-M3G and FERRET, which are reproduced here for convenience:

1. Applicability of WCAP-18124-NP, Revision 0 is limited to the RPV region near the active height of the core based on the uncertainty analysis performed and the measurement data provided.

Additional justification should be provided via additional benchmarking, fluence sensitivity analysis to the response parameters of interest (e.g. pressure-temperature limits, material stress/strain), margin assessment, or a combination thereof, for applications of the method to components including, but not limited to, the RPV upper circumferential weld and the reactor coolant system inlet and outlet nozzles and reactor vessel internal components.

2. Least squares adjustment is acceptable if the adjustments to the M/C ratios and to the calculated spectra values are within the assigned uncertainties of the calculated spectra, the dosimetry measured reaction rates, and the dosimetry reaction cross sections. Should this not be the case, the user should re-examine both measured and calculated values for possible errors. If errors cannot be found, the particular values causing the discrepancy should be disqualified.

The primary purpose of this report is to describe the evaluation of a surveillance capsule. The neutron exposure values applicable to the surveillance capsules and the maximum reactor pressure vessel neutron exposure values used to derive the surveillance capsule lead factors are completely covered by the benchmarking and uncertainty analyses in WCAP-18124-NP. Therefore, Limitation #1 does not strictly apply. Note, however, that this report does contain neutron exposure values for materials that are outside the qualification basis of WCAP-18124-NP (i.e. extended beltline materials). Should values outside the qualification basis of WCAP-18124-NP be cited in future evaluations of reactor vessel integrity, additional justification should be supplied, as stated in Limitation #1.

Limitation #2 applies in situations where the least squares analysis is used to adjust the calculated values of neutron exposure. In this report, the least squares analysis is provided only as a supplemental check on the results of the dosimetry evaluation. The least squares analysis was not used to modify the calculated surveillance capsule or reactor pressure vessel neutron exposure. Therefore, Limitation #2 does not apply.

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Westinghouse Non-Proprietary Class 3 6-7 Table 6-1 Calculated Neutron Exposure Rates at the Geometric Center of the Surveillance Capsules Neutron (E > 1.0 MeV) Fluence Rate Iron Atom Displacement Rate Operating (n/cm2-s) (dpa/s)

Time 34.0° 31.5° 34.0° 34.0° 31.5° 34.0° Cycle (EFPY) Single Dual Dual Single Dual Dual 1 0.74 1.09E+11 9.24E+10 1.10E+11 2.23E-10 1.85E-10 2.24E-10 2 2.00 8.70E+10 7.36E+10 8.75E+10 1.77E-10 1.47E-10 1.77E-10 Table 6-2 Calculated Fast Neutron (E > 1.0 MeV) Fluence at the Geometric Center of the Surveillance Capsules Cumulative Neutron (E > 1.0 MeV) Fluence Operating (n/cm2)

Time Capsule U Capsule V Capsule W Capsule X Capsule Y Capsule Z Cycle (EFPY) (34.0° Dual) (31.5° Dual) (34.0° Single) (34.0° Dual) (31.5° Dual) (34.0° Single) 1 0.74 2.57E+18 2.16E+18 2.56E+18 2.57E+18 2.16E+18 2.56E+18 2 2.00 6.04E+18 5.07E+18 6.00E+18 6.04E+18 5.07E+18 6.00E+18 Future 32.00 - 7.84E+19 9.10E+19 9.16E+19 7.84E+19 9.10E+19 Future 36.00 - 8.83E+19 1.03E+20 1.03E+20 8.83E+19 1.03E+20 Table 6-3 Calculated Iron Atom Displacements (dpa) at the Geometric Center of the Surveillance Capsules Cumulative Iron Atom Displacements Operating (dpa)

Time Capsule U Capsule V Capsule W Capsule X Capsule Y Capsule Z Cycle (EFPY) (34.0° Dual) (31.5° Dual) (34.0° Single) (34.0° Dual) (31.5° Dual) (34.0° Single) 1 0.74 5.23E-03 4.33E-03 5.22E-03 5.23E-03 4.33E-03 5.22E-03 2 2.00 1.23E-02 1.01E-02 1.22E-02 1.23E-02 1.01E-02 1.22E-02 Future 32.00 - 1.56E-01 1.85E-01 1.85E-01 1.56E-01 1.85E-01 Future 36.00 - 1.76E-01 2.08E-01 2.09E-01 1.76E-01 2.08E-01 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 6-8 Table 6-4 Calculated Neutron Fluence Rate for Selected Pressure Vessel Materials Maximum Neutron (E > 1.0 MeV) Fluence Rate (n/cm2-s)

Cumulative Bottom Head Peel 02 Bottom Head Ring 03 Lower Shell 04 Operating to to to Time Bottom Head Ring 03 Lower Shell 04 Int. Shell 05 Cycle (EFPY) Circ. Weld Circ. Weld(a) Lower Shell 04 Circ. Weld 1 0.74 5.68E+06 3.12E+09 2.31E+10 2.19E+10 2 2.00 4.80E+06 2.62E+09 1.88E+10 1.79E+10 Maximum Neutron (E > 1.0 MeV) Fluence Rate (n/cm2-s)

Cumulative Int. Shell 05 Inlet Nozzle Outlet Nozzle Operating to to to Time Upper Shell 06 Upper Shell 06 Weld Upper Shell 06 Weld Cycle (EFPY) Int. Shell 05 Circ. Weld(b) (Lowest Extent) (Lowest Extent) 1 0.74 2.19E+10 5.47E+08 2.42E+07 1.22E+07 2 2.00 1.82E+10 5.05E+08 2.37E+07 1.12E+07 Notes:

(a) The Bottom Head Ring 03 to Lower Shell 04 Circumferential Weld exposure value is representative of the maximum exposure to the Bottom Head Ring 03.

(b) The Intermediate Shell 05 to Upper Shell 06 Circumferential Weld exposure value is representative of the maximum exposure to Upper Shell 06.

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Westinghouse Non-Proprietary Class 3 6-9 Table 6-5 Calculated Neutron Fluence for Selected Pressure Vessel Materials Maximum Neutron (E > 1.0 MeV) Fluence (n/cm2)

Cumulative Bottom Head Peel 02 Bottom Head Ring 03 Lower Shell 04 Operating to to to Time Bottom Head Ring 03 Lower Shell 04 Int. Shell 05 Cycle (EFPY) Circ. Weld Circ. Weld(a) Lower Shell 04 Circ. Weld 1 0.74 1.33E+14 7.29E+16 5.40E+17 5.11E+17 2 2.00 3.23E+14 1.77E+17 1.28E+18 1.22E+18 Future 32.00 4.93E+15 2.47E+18 1.94E+19 1.83E+19 Future 36.00 5.55E+15 2.78E+18 2.19E+19 2.06E+19 Maximum Neutron (E > 1.0 MeV) Fluence (n/cm2)

Cumulative Int. Shell 05 Inlet Nozzle Outlet Nozzle Operating to to to Time Upper Shell 06 Upper Shell 06 Weld Upper Shell 06 Weld Cycle (EFPY) Int. Shell 05 Circ. Weld(b) (Lowest Extent) (Lowest Extent) 1 0.74 5.12E+17 1.28E+16 5.64E+14 2.85E+14 2 2.00 1.23E+18 3.28E+16 1.50E+15 7.06E+14 Future 32.00 1.86E+19 5.12E+17 2.40E+16 1.16E+16 Future 36.00 2.10E+19 5.75E+17 2.70E+16 1.31E+16 Notes:

(a) The Bottom Head Ring 03 to Lower Shell 04 Circumferential Weld exposure value is representative of the maximum exposure to the Bottom Head Ring 03.

(b) The Intermediate Shell 05 to Upper Shell 06 Circumferential Weld exposure value is representative of the maximum exposure to Upper Shell 06.

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Westinghouse Non-Proprietary Class 3 6-10 Table 6-6 Calculated dpa/s for Selected Pressure Vessel Materials Maximum Iron Atom Displacement Rate (dpa/s)

Cumulative Bottom Head Peel 02 Bottom Head Ring 03 Lower Shell 04 Operating to to to Time Bottom Head Ring 03 Lower Shell 04 Int. Shell 05 Cycle (EFPY) Circ. Weld Circ. Weld(a) Lower Shell 04 Circ. Weld 1 0.74 3.94E-14 4.97E-12 3.67E-11 3.49E-11 2 2.00 3.29E-14 4.17E-12 2.98E-11 2.86E-11 Maximum Iron Atom Displacement Rate (dpa/s)

Cumulative Int. Shell 05 Inlet Nozzle Outlet Nozzle Operating to to to Time Upper Shell 06 Upper Shell 06 Weld Upper Shell 06 Weld Cycle (EFPY) Int. Shell 05 Circ. Weld(b) (Lowest Extent) (Lowest Extent) 1 0.74 3.49E-11 9.10E-13 1.06E-13 7.84E-14 2 2.00 2.89E-11 8.36E-13 9.07E-14 6.73E-14 Notes:

(a) The Bottom Head Ring 03 to Lower Shell 04 Circumferential Weld exposure value is representative of the maximum exposure to the Bottom Head Ring 03.

(b) The Intermediate Shell 05 to Upper Shell 06 Circumferential Weld exposure value is representative of the maximum exposure to Upper Shell 06.

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Westinghouse Non-Proprietary Class 3 6-11 Table 6-7 Calculated dpa for Selected Pressure Vessel Materials Maximum Iron Atom Displacements (dpa)

Cumulative Bottom Head Peel 02 Bottom Head Ring 03 Lower Shell 04 Operating to to to Time Bottom Head Ring 03 Lower Shell 04 Int. Shell 05 Cycle (EFPY) Circ. Weld Circ. Weld(a) Lower Shell 04 Circ. Weld 1 0.74 9.19E-07 1.16E-04 8.57E-04 8.15E-04 2 2.00 2.22E-06 2.81E-04 2.04E-03 1.95E-03 Future 32.00 3.39E-05 3.94E-03 3.04E-02 2.91E-02 Future 36.00 3.81E-05 4.43E-03 3.42E-02 3.28E-02 Maximum Iron Atom Displacements (dpa)

Cumulative Int. Shell 05 Inlet Nozzle Outlet Nozzle Operating to to to Time Upper Shell 06 Upper Shell 06 Weld Upper Shell 06 Weld Cycle (EFPY) Int. Shell 05 Circ. Weld(b) (Lowest Extent) (Lowest Extent) 1 0.74 8.16E-04 2.13E-05 2.47E-06 1.83E-06 2 2.00 1.96E-03 5.44E-05 6.06E-06 4.50E-06 Future 32.00 2.94E-02 8.50E-04 9.94E-05 7.38E-05 Future 36.00 3.31E-02 9.55E-04 1.12E-04 8.31E-05 Notes:

(a) The Bottom Head Ring 03 to Lower Shell 04 Circumferential Weld exposure value is representative of the maximum exposure to the Bottom Head Ring 03.

(b) The Intermediate Shell 05 to Upper Shell 06 Circumferential Weld exposure value is representative of the maximum exposure to Upper Shell 06.

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Westinghouse Non-Proprietary Class 3 6-12 Table 6-8 Calculated Surveillance Capsule Lead Factors Cumulative Lead Factor Operating Time Capsule U Capsule V Capsule W Capsule X Capsule Y Capsule Z Cycle (EFPY) (34.0° Dual) (31.5° Dual) (34.0° Single) (34.0° Dual) (31.5° Dual) (34.0° Single) 1 0.74 4.76 4.00 4.73 4.76 4.00 4.73 2 2.00 4.70 3.95 4.67 4.70 3.95 4.67 Future 7.34(a) - 3.95 4.66 4.69 3.95 4.66 Future 32.00 - 4.04 4.69 4.72 4.04 4.69 Future 36.00 - 4.03 4.68 4.71 4.03 4.68 Notes:

(a) 7.34 EFPY is the expected reactor operating time following the end of Cycle 6, and represents the interval at which Capsule W should be removed. See Section 7 for more information about the recommended schedule for removing surveillance capsules.

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Westinghouse Non-Proprietary Class 3 6-13 Figure 6-1 Watts Bar Unit 2 Plan View of the Reactor Geometry at the Core Midplane 15.0° Neutron Pad Configuration WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 6-14 Figure 6-2 Watts Bar Unit 2 Plan View of the Reactor Geometry at the Core Midplane 17.5° Neutron Pad Configuration WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 6-15 Figure 6-3 Watts Bar Unit 2 Plan View of the Reactor Geometry at the Core Midplane 20.0° Neutron Pad Configuration WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 6-16 Figure 6-4 Watts Bar Unit 2 Section View of the Reactor Geometry at the 34.0° Azimuthal Angle - 20.0° Neutron Pad Configuration WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 7-1 7 SURVEILLANCE CAPSULE REMOVAL SCHEDULE The following surveillance capsule removal schedule (Table 7-1) meets the requirements of ASTM E185-82

[Ref. 8]. Note that it is recommended for future capsule(s) to be removed from the Watts Bar Unit 2 reactor vessel.

Table 7-1 Surveillance Capsule Withdrawal Schedule Fluence Capsule Capsule Location Lead Factor Withdrawal EFPY(a) (n/cm2, E > 1.0 MeV) 2.0 EFPY U Dual 34° 4.70 0.604 x 1019 (EOC 2) 7.0 EFPY(b)

W Single 34° 4.66 1.94 x 1019 (EOC 6) 7.0 EFPY to 1.94 x 1019 to X Dual 34° 4.69 13.7 EFPY(c) 3.88 x 1019 (c)

Z Single 34° 4.69 Standby(d) - - -(d)

V Dual 31.5° 4.04 Standby(d) - - -(d)

Y Dual 31.5° 4.04 Standby(d) - - -(d)

Notes:

(a) Effective full-power years (EFPY) from plant startup. The projected EFPY and end-of-cycle (EOC) values assume the Measurement Uncertainty Recapture (MUR) uprate and TPBARs are implemented at the beginning of Cycle 4.

(b) This capsule should be withdrawn at the outage nearest to but following 7.0 EFPY of operation. This outage is projected to occur at EOC 6. However, the capsule withdrawal should be based on actual plant EFPY as opposed to the estimated cycle.

(c) Capsule X must be withdrawn between 7.0 EFPY and 13.7 EFPY in order satisfy the requirements of the third capsule for EOL per ASTM E185-82 [Ref. 8]. However, if the capsule is removed after 11.7 EFPY (but still before 13.7 EFPY), this capsule will satisfy the requirements of the third capsule for both end of license (EOL, 40 years) and end of a potential license extension (60 years) per ASTM E185-82 [Ref. 8] and NUREG-1801, Revision 2 [Ref. 18]. Thus, if possible, the capsule should be pulled between 11.7 EFPY and 13.7 EFPY, but the capsule must be pulled between 7.0 EFPY and 13.7 EFPY. The removal EFPY of the third capsule should be revisited at a later date, such as after Capsule W is removed.

(d) Capsules Z, V, and Y should remain in the reactor. The potential for future removal and storage of some or all of these standby capsules should be revisited at a later date, such as with the withdrawal and testing of Capsule W. If additional metallurgical data is needed, such as in support of a first (60 years) or second (80 years) license renewal, withdrawal and testing of these capsules should be considered when planning for withdrawal of Capsule X in anticipation of any license renewal effort. Note, ASTM E185-82 and NUREG-1801, Revision 2 recommend that the capsules not experience twice the end of life fluence. Therefore, the potential for future removal and storage of some or all of these standby capsules should be revisited at a later date, such as with the withdrawal and testing of Capsule W.

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Westinghouse Non-Proprietary Class 3 8-1 8 REFERENCES

1. U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, Regulatory Guide 1.99, Revision 2, Radiation Embrittlement of Reactor Vessel Materials, May 1988.

[Agencywide Documents Access and Management System (ADAMS) Accession Number ML003740284]

2. Westinghouse Report WCAP-9455, Revision 4, Tennessee Valley Authority Watts Bar Unit No. 2 Reactor Vessel Radiation Surveillance Program, August 2019.
3. ASTM E185-73, Standard Recommended Practice for Surveillance Tests for Nuclear Reactor Vessels, 1973.
4. Appendix G of the ASME Boiler and Pressure Vessel (B&PV) Code,Section XI, Division 1, Fracture Toughness Criteria for Protection Against Failure.
5. ASTM E208, Standard Test Method for Conducting Drop-Weight Test to Determine Nil-Ductility Transition Temperature of Ferritic Steels, ASTM.
6. ASTM E399, Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness Klc of Metallic Materials, ASTM.
7. 10 CFR 50, Appendix H, Reactor Vessel Material Surveillance Program Requirements, U.S.

Nuclear Regulatory Commission, Federal Register, November 29, 2019.

8. ASTM E185-82, Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels, American Society for Testing and Materials, 1982.
9. ASTM E23-18, Standard Test Methods for Notched Bar Impact Testing of Metallic Materials, 2018.
10. ASTM E2298-18, Standard Test Method for Instrumented Impact Testing of Metallic Materials, 2018.
11. ASTM A370-18, Standard Test Methods and Definitions for Mechanical Testing of Steel Products, 2018.
12. ASTM E8/E8M-16, Standard Test Methods for Tension Testing of Metallic Materials, 2016.
13. ASTM E21-17, Standard Test Methods for Elevated Temperature Tension Tests of Metallic Materials, 2017.
14. ASTM E853-18, Standard Practice for Analysis and Interpretation of Light-Water Reactor Surveillance Neutron Exposure Results, 2018.
15. ASTM E693-94, Standard Practice for Characterizing Neutron Exposures in Iron and Low Alloy Steels in Terms of Displacements Per Atom (DPA), E706 (ID), 1994.

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Westinghouse Non-Proprietary Class 3 8-2

16. U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, Regulatory Guide 1.190, Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence, March 2001. [ADAMS Accession Number ML010890301]
17. Westinghouse Report WCAP-18124-NP-A, Revision 0, Fluence Determination with RAPTOR-M3G and FERRET, July 2018. [ADAMS Accession Number ML18204A010]
18. NUREG-1801, Revision 2, Generic Aging Lessons Learned (GALL) Report, December 2010, U.S. Nuclear Regulatory Commission Report. [ADAMS Accession Number ML103490041]

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Westinghouse Non-Proprietary Class 3 A-1 APPENDIX A VALIDATION OF THE RADIATION TRANSPORT MODELS BASED ON NEUTRON DOSIMETRY MEASUREMENTS NEUTRON DOSIMETRY Comparisons of measured dosimetry results to both the calculated and least-squares adjusted values for Capsule U are provided in this appendix. The sensor sets have been analyzed in accordance with the current dosimetry evaluation methodology described in Regulatory Guide 1.190, Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence [Ref. A-1]. One of the main purposes for providing this material is to demonstrate that the overall measurements agree with the calculated and least-squares adjusted values to within 20% as specified by Regulatory Guide 1.190, thus serving to validate the calculated neutron exposures previously reported in Section 6.2 of this report.

A.1.1 Sensor Reaction Rate Determinations In this section, the results of the evaluations of Capsule U are presented. The capsule designation, location within the reactor, and time of withdrawal are as follows:

Capsule Azimuthal Withdrawal Irradiation Time Location Time (EFPY)

U 56º End of Cycle 2 2.00 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 A-2 The passive neutron sensors included in these evaluations are summarized as follows:

Sensor Material Reaction Of Interest Capsule U Copper Cu-63 (n,) Co-60 X Iron Fe-54 (n,p) Mn-54 X Nickel Ni-58 (n,p) Co-58 X Uranium-238 U-238 (n,f) Cs-137 X Neptunium-237 Np-237 (n,f) Cs-137 X Cobalt-Aluminum(a) Co-59 (n,) Co-60 X Notes:

(a) The cobalt-aluminum and uranium sensors include both bare and cadmium-covered sensors.

Since all of the dosimetry monitors were located at the radial center of the material test specimen array, gradient corrections were not required for these reaction rates. Pertinent physical and nuclear characteristics of the passive neutron sensors analyzed are listed in Table A-1.

The use of passive monitors does not yield a direct measure of the energy-dependent neutron exposure rate at the point of interest. Rather, the activation or fission process is a measure of the integrated effect that the time- and energy-dependent neutron exposure rate has on the target material over the course of the irradiation period. An accurate assessment of the average neutron exposure rate incident on the various monitors may be derived from the activation measurements only if the irradiation parameters are well known. In particular, the following variables are of interest:

the measured specific activity of each monitor, the physical characteristics of each monitor, the operating history of the reactor, the energy response of each monitor, and the neutron energy spectrum at the monitor location.

The radiometric counting of the sensors from Capsule U was carried out by Pace Analytical Services, Inc.

The radiometric counting followed established ASTM procedures.

The irradiation history of the reactor over the irradiation periods was based on the monthly power generation of Watts Bar Unit 2 from initial reactor criticality through the end of the dosimetry evaluation period. For the sensor sets utilized in the surveillance capsules, the half-lives of the product isotopes are long enough that a monthly histogram describing reactor operation has proven to be an adequate representation for use in radioactive decay corrections for the reactions of interest in the exposure evaluations. The irradiation history is given in Table A-2.

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Westinghouse Non-Proprietary Class 3 A-3 Having the measured specific activities, the physical characteristics of the sensors, and the operating history of the reactor, reaction rates referenced to full-power operation were determined from the following equation:

A R

P N FY C 1 e e ,

P where:

R = Reaction rate averaged over the irradiation period and referenced to operation at a core power level of Pref (rps/nucleus).

A = Measured specific activity (dps/g).

N0 = Number of target element atoms per gram of sensor.

F = Atom fraction of the target isotope in the target element.

Y = Number of product atoms produced per reaction.

Pj = Average core power level during irradiation period j (MW).

Pref = Maximum or reference power level of the reactor (MW).

Cj = Calculated ratio of (E > 1.0 MeV) during irradiation period j to the time weighted average (E > 1.0 MeV) over the entire irradiation period.

= Decay constant of the product isotope (1/sec).

tj = Length of irradiation period j (sec).

td,j = Decay time following irradiation period j (sec).

The summation is carried out over the total number of monthly intervals comprising the irradiation period.

In the equation describing the reaction rate calculation, the ratio [Pj]/[Pref] accounts for month-by-month variation of reactor core power level within any given fuel cycle as well as over multiple fuel cycles. The ratio Cj, which was calculated for each fuel cycle using the transport methodology discussed in Section 6.2, accounts for the change in sensor reaction rates caused by variations in exposure rate level induced by changes in core spatial power distributions from fuel cycle to fuel cycle. For a single-cycle irradiation, Cj is normally taken to be 1.0. However, for multiple-cycle irradiations, the additional Cj term should be employed. The impact of changing exposure rate levels for constant power operation can be quite significant for sensor sets that have been irradiated for many cycles in a reactor that has transitioned from non-low-leakage to low-leakage fuel management or for sensor sets contained in surveillance capsules that have been moved from one capsule location to another.

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Westinghouse Non-Proprietary Class 3 A-4 The fuel-cycle-specific neutron exposure rates and the computed values for Cj are listed in Table A-3 and Table A-4, respectively. These exposure rates represent the capsule- and cycle-dependent results at the radial and azimuthal center of the respective capsules at core midplane.

Prior to using the measured reaction rates in the least-squares evaluations of the dosimetry sensor sets, additional corrections were made to the U-238 measurements to account for the presence of 235U impurities in the sensors, as well as to adjust for the build-in of plutonium isotopes over the course of the irradiation.

Corrections were also made to the U-238 and Np-237 sensor reaction rates to account for gamma-ray-induced fission reactions that occurred over the course of the surveillance capsule irradiations. The correction factors corresponding to the Watts Bar Unit 2 fission sensor reaction rates are summarized as follows:

Correction Capsule U U-235 Impurity/Pu Build-in 0.8609 U-238 (,f) 0.9637 Net U-238 Correction 0.8296 Np-237 (,f) 0.9898 The correction factors were applied in a multiplicative fashion to the decay-corrected cadmium-covered uranium fission sensor reaction rates.

Results of the sensor reaction rate determinations are given in Table A-5. In Table A-5, the measured specific activities, decay-corrected saturated specific activities, and computed reaction rates for each sensor are listed.

A.1.2 Least-Squares Evaluation of Sensor Sets Least-squares adjustment methods provide the capability of combining the measurement data with the corresponding neutron transport calculations resulting in a best-estimate neutron energy spectrum with associated uncertainties. Best-estimates for key exposure parameters such as fluence rate (E > 1.0 MeV) or dpa/s along with their uncertainties are then easily obtained from the adjusted spectrum. In general, the least-squares methods, as applied to dosimetry evaluations, act to reconcile the measured sensor reaction rate data, dosimetry reaction cross-sections, and the calculated neutron energy spectrum within their respective uncertainties. For example, R i R i ( ig ig )( g g )

g relates a set of measured reaction rates, Ri, to a single neutron spectrum, g, through the multigroup dosimeter reaction cross-sections, ig, each with an uncertainty . The primary objective of the least-squares evaluation is to produce unbiased estimates of the neutron exposure parameters at the location of the measurement.

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Westinghouse Non-Proprietary Class 3 A-5 For the least-squares evaluation of the Watts Bar Unit 2 dosimetry, the FERRET code [Ref. A-2] was employed to combine the results of the plant-specific neutron transport calculations and sensor set reaction rate measurements to determine the best-estimate values of exposure parameters (fluence rate (E > 1.0 MeV) and dpa) and their associated uncertainties.

The application of the least-squares methodology requires the following input:

1. The calculated neutron energy spectrum and associated uncertainties at the measurement location.
2. The measured reaction rates and associated uncertainty for each sensor contained in the multiple foil set.
3. The energy-dependent dosimetry reaction cross-sections and associated uncertainties for each sensor contained in the multiple foil sensor set.

For the Watts Bar Unit 2 application, the calculated neutron spectrum was obtained from the results of plant-specific neutron transport calculations described in Section 6.2 of this report. The sensor reaction rates were derived from the measured specific activities using the procedures described in Section A.1.1. The dosimetry reaction cross-sections and uncertainties were obtained from the SNLRML dosimetry cross-section library [Ref. A-3].

The uncertainties associated with the measured reaction rates, dosimetry cross-sections, and calculated neutron spectrum were input to the least-squares procedure in the form of variances and covariances. The assignment of the input uncertainties followed the guidance provided in ASTM Standard E944, Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance [Ref. A-4].

The following provides a summary of the uncertainties associated with the least-squares evaluation of the Watts Bar Unit 2 surveillance capsule sensor sets.

Reaction Rate Uncertainties The overall uncertainty associated with the measured reaction rates includes components due to the basic measurement process, irradiation history corrections, and corrections for competing reactions. A high level of accuracy in the reaction rate determinations is ensured by utilizing laboratory procedures that conform to the ASTM National Consensus Standards for reaction rate determinations for each sensor type.

After combining all of these uncertainty components, the sensor reaction rates derived from the counting and data evaluation procedures were assigned the following net uncertainties for input to the least-squares evaluation:

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Westinghouse Non-Proprietary Class 3 A-6 Reaction Uncertainty 63 Cu (n,) 60Co 5%

54 Fe (n,p) 54Mn 5%

58 Ni (n,p) 58Co 5%

59 Co (n,) 60Co 5%

238 U (n,f) FP 10%

237 Np (n,f) FP 10%

These uncertainties are given at the 1 level.

Dosimetry Cross-Section Uncertainties The reaction rate cross-sections used in the least-squares evaluations were taken from the SNLRML library.

This data library provides reaction cross-sections and associated uncertainties, including covariances, for 66 dosimetry sensors in common use. Both cross-sections and uncertainties are provided in a fine multigroup structure for use in least-squares adjustment applications. These cross-sections were compiled from recent cross-section evaluations, and they have been tested for accuracy and consistency for least-squares evaluations. Further, the library has been empirically tested for use in fission spectra determination, as well as in the fluence and energy characterization of 14 MeV neutron sources.

For sensors included in the Watts Bar Unit 2 surveillance program, the following uncertainties in the fission spectrum averaged cross-sections are provided in the SNLRML documentation package.

Reaction Uncertainty Cu-63 (n,) Co-60 4.08-4.16%

Fe-54 (n,p) Mn-54 3.05-3.11%

Ni-58 (n,p) Co-58 4.49-4.56%

Co-59 (n,) Co-60 0.79-3.59%

U-238 (n,f) 0.54-0.64%

Np-237 (n,f) 10.32-10.97%

These tabulated ranges provide an indication of the dosimetry cross-section uncertainties associated with the sensor sets used in LWR irradiations.

Calculated Neutron Spectrum The neutron spectra inputs to the least-squares adjustment procedure were obtained directly from the results of plant-specific transport calculations for each surveillance capsule irradiation period and location. The spectrum for each capsule was input in an absolute sense (rather than as simply a relative spectral shape).

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Westinghouse Non-Proprietary Class 3 A-7 Therefore, within the constraints of the assigned uncertainties, the calculated data were treated equally with the measurements.

While the uncertainties associated with the reaction rates were obtained from the measurement procedures and counting benchmarks and the dosimetry cross-section uncertainties were supplied directly with the SNLRML library, the uncertainty matrix for the calculated spectrum was constructed from the following relationship:

M gg' R 2n R g

  • R g'
  • Pgg' where Rn specifies an overall fractional normalization uncertainty and the fractional uncertainties Rg and Rg specify additional random groupwise uncertainties that are correlated with a correlation matrix given by:

Pgg = [1 - ] gg + e-H Where:

(g g' ) 2 H

2 2 The first term in the correlation matrix equation specifies purely random uncertainties, while the second term describes the short-range correlations over a group range ( specifies the strength of the latter term).

The value of is 1.0 when g = g, and is 0.0 otherwise.

The set of parameters defining the input covariance matrix for the Watts Bar Unit 2 calculated spectra was as follows:

Exposure Rate Normalization Uncertainty (Rn) 15%

Exposure Rate Group Uncertainties (Rg, Rg)

(E > 0.0055 MeV) 15%

(0.68 eV < E < 0.0055 MeV) 25%

(E < 0.68 eV) 50%

Short Range Correlation ()

(E > 0.0055 MeV) 0.9 (0.68 eV < E < 0.0055 MeV) 0.5 (E < 0.68 eV) 0.5 Exposure Rate Group Correlation Range ()

(E > 0.0055 MeV) 6 (0.68 eV < E < 0.0055 MeV) 3 (E < 0.68 eV) 2 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 A-8 A.1.3 Comparisons of Measurements and Calculations Results of the least-squares evaluations are provided in Table A-6. In these tables, measured, calculated, and best-estimate values for sensor reaction rates are given. Also provided in these tabulations are ratios of the measured reaction rates to both the calculated and least-squares adjusted reaction rates. These ratios of measured-to-calculated (M/C) and measured-to-best estimate (M/BE) illustrate the consistency of the fit of the calculated neutron energy spectra to the measured reaction rates both before and after adjustment.

Additionally, comparisons of the calculated and best-estimate values of neutron fluence rate (E > 1.0 MeV) and iron atom displacement rate are tabulated along with the best estimate-to-calculated (BE/C) ratios observed for each of the capsules.

The data comparisons provided in Table A-6 show that the adjustments to the calculated spectra are relatively small and within the assigned uncertainties for the calculated spectra, measured sensor reaction rates, and dosimetry reaction cross-sections. Further, these results indicate that the use of the least-squares evaluation results in a reduction in the uncertainties associated with the exposure of the surveillance capsules. From Section 6.4 of this report, the calculational uncertainty is specified as 13% at the 1 level.

Further comparisons of the measurement results with calculations are given in Table A-7 and Table A-8. In Table A-7, calculations of individual threshold sensor reaction rates are compared directly with the corresponding measurements. These threshold reaction rate comparisons provide a good evaluation of the accuracy of the fast neutron portion of the calculated energy spectra. In Table A-8, calculations of fast neutron exposure rates in terms of fast neutron (E > 1.0 MeV) fluence rate and dpa/s are compared with the best-estimate results obtained from the least-squares evaluation of the capsule dosimetry results. These comparisons yield consistent and similar results with all measurement-to-calculation comparisons falling within the 20% limits specified as the acceptance criteria in Regulatory Guide 1.190.

In the case of the direct comparison of the measured and calculated sensor reaction rates, for the individual threshold foils considered in the least-squares analysis, the M/C comparisons of the fast neutron threshold reactions range from 0.72 to 1.01. The overall average M/C ratio is 0.92 with an associated standard deviation of 12.7%.

In the case of the comparison of the best-estimate and calculated fast neutron exposure parameters, the BE/C comparisons are 0.92 and 0.93 for fast neutron (E > 1.0 MeV) fluence rate and iron atom displacement rate, respectively.

Based on these comparisons, it is concluded that the calculated fast neutron exposures provided in Section 6.2 of this report are validated for use in the assessment of the condition of the materials comprising the beltline region of the Watts Bar Unit 2 reactor pressure vessel.

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Westinghouse Non-Proprietary Class 3 A-9 Table A-1 Nuclear Parameters Used in the Evaluation of Neutron Sensors 90%

Atomic Target Product Fission Reaction of Response Weight Atom Half-life Yield Interest Range(a)

(g/g-atom) Fraction (days) (%)

(MeV)

Cu-63 (n,) Co-60 63.546 0.6917 1925.28 - 4.53-11.0 Fe-54 (n,p) Mn-54 55.845 0.05845 312.13 - 2.27-7.54 Ni-58 (n,p) Co-58 58.693 0.68077 70.86 - 1.98-7.51 Co-59 (n,) Co-60 58.933 0.0015 1925.28 - non-threshold U-238 (n,f) Cs-137 238.051 1.00 10975.76 0.0602 1.44-6.69 Np-237 (n,f) Cs-137 237.048 1.00 10975.76 0.0627 0.68-5.61 Note:

(a) Energies between which 90% of activity is produced (U-235 fission spectrum) [Ref. A-5]

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Westinghouse Non-Proprietary Class 3 A-10 Table A-2 Monthly Thermal Generation for the Watts Bar Unit 2 Reactor Cycle 1 Cycle 2 Month MWt-h Month MWt-h May-16 30290 Dec-17 1491562 Jun-16 347922 Jan-18 2530416 Jul-16 1056046 Feb-18 2287280 Aug-16 664736 Mar-18 2532054 Sep-16 314358 Apr-18 2210328 Oct-16 1745340 May-18 2440366 Nov-16 2369963 Jun-18 1738791 Dec-16 2526323 Jul-18 2432179 Jan-17 2530416 Aug-18 2020404 Feb-17 2284824 Sep-18 2451827 Mar-17 1588980 Oct-18 2534509 Apr-17 0 Nov-18 2455101 May-17 0 Dec-18 2536965 Jun-17 819 Jan-19 2535328 Jul-17 18829 Feb-19 1829660 Aug-17 2011398 Mar-19 2534509 Sep-17 2446915 Apr-19 970907 Oct-17 2184950 Nov-17 0 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 A-11 Table A-3 Surveillance Capsule Fluence Rates for Cj Calculation, Core Midplane Elevation Fluence Rate Cycle (E > 1.0 MeV, n/cm2-s)

Cycle Length (EFPY) CapsuleU 1 0.74 1.10E+11 2 1.26 8.75E+10 Average -- 9.59E+10 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 A-12 Table A-4 Surveillance Capsule Cj Factors, Core Midplane Elevation Cj Cycle Cycle Length Capsule U (EFPY) 1 0.74 1.15 2 1.26 0.91 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 A-13 Table A-5 Measured Sensor Activities and Reaction Rates for Surveillance Capsule U Corrected Average Measured Saturated Reaction Average Sample Target Product Reaction Activity(b) Activity Rate Reaction ID Isotope(a) Isotope Rate (dps/g) (dps/g) (rps/atom) Rate (rps/atom)

(rps/atom) 6 Cu-63 Co-60 5.71E+04 2.63E+05 4.01E-17 12 Cu-63 Co-60 6.04E+04 2.78E+05 4.25E-17 18 Cu-63 Co-60 5.80E+04 2.67E+05 4.08E-17 4.11E-17 4.11E-17 8 Fe-54 Mn-54 1.96E+06 3.30E+06 5.24E-15 14 Fe-54 Mn-54 2.09E+06 3.52E+06 5.58E-15 20 Fe-54 Mn-54 1.83E+06 3.08E+06 4.89E-15 5.24E-15 5.24E-15 7 Ni-58 Co-58 2.08E+07 4.95E+07 7.08E-15 13 Ni-58 Co-58 2.14E+07 5.09E+07 7.29E-15 19 Ni-58 Co-58 2.13E+07 5.07E+07 7.26E-15 7.21E-15 7.21E-15 1 U-238 Cs-137 1.75E+05 3.93E+06 2.58E-14 2.58E-14 2.14E-14 2 Np-237 Cs-137 2.21E+06 4.97E+07 3.12E-13 3.12E-13 3.09E-13 3 Co-59 (B) Co-60 1.73E+07 7.97E+07 5.20E-12 4 Co-59 (B) Co-60 1.59E+07 7.33E+07 4.78E-12 9 Co-59 (B) Co-60 1.62E+07 7.46E+07 4.87E-12 10 Co-59 (B) Co-60 1.39E+07 6.40E+07 4.18E-12 15 Co-59 (B) Co-60 1.70E+07 7.83E+07 5.11E-12 16 Co-59 (B) Co-60 1.49E+07 6.86E+07 4.48E-12 4.77E-12 4.77E-12 5 Co-59 Co-60 8.73E+06 4.02E+07 2.62E-12 11 Co-59 Co-60 9.16E+06 4.22E+07 2.75E-12 17 Co-59 Co-60 9.11E+06 4.20E+07 2.74E-12 2.71E-12 2.71E-12 Note:

(a) (B) denotes Bare for the Co-59 sensors; the other Co-59 sensors are cadmium-shielded.

(b) Measured activity is decay corrected to 6/25/2019.

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Westinghouse Non-Proprietary Class 3 A-14 Table A-6 Least-Squares Evaluation of Dosimetry in Capsule U (34° Dual Position, Core Midplane, Withdrawn at the End of Cycle 2)

Capsule U - 34.0° Dual - Withdrawn EOC 2 2/DOF= 0.897 Best Measured Calculated Estimate Reaction (rps/atom) (rps/atom) (rps/atom) M/C M/BE BE/C Cu-63(n,a)Co-60 4.11E-17 4.52E-17 4.20E-17 0.91 0.98 0.93 Fe-54(n,p)Mn-54 5.24E-15 5.29E-15 5.02E-15 0.99 1.04 0.95 Ni-58(n,p)Co-58 7.21E-15 7.48E-15 7.07E-15 0.96 1.02 0.94 Co-59(n,g)Co-60 4.77E-12 5.03E-12 4.74E-12 0.95 1.01 0.94 Co-59(n,g)Co-60 Cd 2.70E-12 3.28E-12 2.73E-12 0.82 0.99 0.83 U-238(n,f) Cd 2.14E-14 2.98E-14 2.76E-14 0.72 0.78 0.93 Np-237(n,f) Cd 3.09E-13 3.07E-13 2.95E-13 1.01 1.04 0.96 Threshold Foil Average 0.92 0.97 0.94

% Standard Deviation 12.7 11.3 1.4 Integral Quantity Units Calculated  % Unc. Best Est.  % Unc. BE/C Fluence Rate (E > 1.0 MeV) n/cm2-s 9.64E+10 13 8.91E+10 6 0.92 Iron Displacement Rate dpa/s 1.92E-10 13 1.78E-10 8 0.93 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 A-15 Table A-7 Comparison of Measured/Calculated (M/C) Sensor Reaction Rate Ratios for Fast Neutron Threshold Reactions M/C Ratio Capsule Cu-63 (n,) Fe-54 (n,p) Ni-58 (n,p) U-238 (n,f) Np-237 (n,f)

U 0.91 0.99 0.96 0.72 1.01 Average 0.91 0.99 0.96 0.72 1.01

% Standard Deviation Reaction Average M/C  % Standard Deviation Cu-63 (n,) 0.91 -

Fe-54 (n,p) 0.99 -

Ni-58 (n,p) 0.96 -

U-238 (n,f) 0.72 -

Np-237 (n,f) 1.01 -

Linear Average 0.92 12.7 Table A-8 Comparison of Best-Estimate/Calculated (BE/C) Exposure Rate Ratios Neutron (E > 1.0 MeV)

Fluence Rate Iron Displacement Rate

% Standard  % Standard Capsule BE/C Deviation BE/C Deviation U 0.92 6 0.93 8 Average 0.92 - 0.93 -

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Westinghouse Non-Proprietary Class 3 A-16 REFERENCES A-1 U.S. Nuclear Regulatory Commission Regulatory Guide 1.190, Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence, March 2001.

A-2 A. Schmittroth, FERRET Data Analysis Core, HEDL-TME 79-40, Hanford Engineering Development Laboratory, Richland, WA, September 1979.

A-3 RSICC Data Library Collection DLC-178, SNLRML Recommended Dosimetry Cross-Section Compendium, July 1994.

A-4 ASTM Standard E944-19, Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance, 2019.

A-5 ASTM Standard E844-18, Standard Guide for Sensor Set Design and Irradiation for Reactor Surveillance, 2018.

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Westinghouse Non-Proprietary Class 3 B-1 APPENDIX B LOAD-TIME RECORDS FOR CHARPY SPECIMEN TESTS FROM CAPSULE U BLXX denotes Intermediate Shell Forging 05, tangential orientation BTXX denotes Intermediate Shell Forging 05, axial orientation BWXX denotes weld material BHXX denotes heat-affected zone material Note that the instrumented Charpy data is not required per ASTM Standards E185-82 or E23-18.

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Westinghouse Non-Proprietary Class 3 B-2 BL10 tested at -60 °F.

BL4 tested at -50 °F.

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Westinghouse Non-Proprietary Class 3 B-3 BL8: Tested at -30°F BL15: Tested at -20°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-4 BL6: Tested at -15°F BL3: Tested at -10°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-5 BL5: Tested at -5°F BL11: Tested at 0°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-6 BL1: Tested at 10°F BL9: Tested at 40°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-7 BL13: Tested at 75°F BL2: Tested at 120°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-9 BL12: Tested at 220°F BT1: Tested at -60°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-14 BT12: Tested at 30°F BT14: Tested at 75°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-16 BT11: Tested at 200°F BT7: Tested at 220°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-23 BW5: Tested at 170°F BW10: Tested at 200°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-24 BW11: Tested at 220°F BH5: Tested at -115°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-25 BH3: Tested at -110°F BH10: Tested at -100°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-27 BH7: Tested at -70°F BH15: Tested at -60°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-28 BH14: Tested at -35°F BH8: Tested at -30°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-29 BH11: Tested at -20°F BH1: Tested at 10°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-30 BH4: Tested at 75°F BH13: Tested at 150°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 B-31 BH6: Tested at 200°F BH9: Tested at 220°F WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-1 APPENDIX C CHARPY V-NOTCH PLOTS FOR BASELINE AND CAPSULE U USING SYMMETRIC HYPERBOLIC TANGENT CURVE-FITTING METHOD METHODOLOGY Contained in Table C-1 are the upper-shelf energy (USE) values that are used as input for the generation of the Charpy V-notch plots using CVGRAPH, Version 6.02. The definition for USE is given in ASTM E185-82 [Ref. C-1], Section 4.18, and reads as follows:

upper shelf energy level - the average energy value for all Charpy specimens (normally three) whose test temperature is above the upper end of the transition region. For specimens tested in sets of three at each test temperature, the set having the highest average may be regarded as defining the upper shelf energy.

Westinghouse reports the average of all Charpy data ( 95% shear) as the USE, excluding any values that are deemed outliers using engineering judgment. Hence, the Capsule U USE values reported in Table C-1 were determined by applying this methodology to the Charpy data tabulated in Table 5-1 through Table 5-4 of this report. USE values documented in Table C-1 for the unirradiated material were also determined by applying the methodology described above to the Charpy impact data reported in WCAP-9455 [Refs. C-2 and C-3]. The USE values reported in Table C-1 were used in generation of the Charpy V-notch curves.

The lower-shelf energy values were fixed at 2.2 ft-lb for all cases. The lower-shelf lateral expansion values were fixed at 1.0 mil in order to be consistent with the previous capsule analysis. Similarly, the upper-shelf energy must also be fixed for curve-fitting the Charpy V-Notch (CVN) Energy data using the values reported in in Table C-1. However, the upper-shelf lateral expansion is not fixed in CVGRAPH.

USE is expected to decrease as a function of fluence and copper content. As expected, this decrease in USE was exhibited from the unirradiated materials to the Capsule U materials.

WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-2 Table C-1 Upper-Shelf Energy Values (ft-lb) Fixed in CVGRAPH Unirradiated Capsule U Material (ft-lb) (ft-lb)

Intermediate Shell Forging 05, Heat # 527828 175 130 (Tangential)

Intermediate Shell Forging 05, Heat # 527828 110 105 (Axial)

Weld Metal 144 135 Heat # 895075 HAZ 130 118 CVGRAPH, Version 6.02 plots of all surveillance data are provided in this appendix, on the pages following the reference list.

REFERENCES C-1 ASTM E185-82, Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels, American Society for Testing and Materials, 1982.

C-2 Westinghouse Report WCAP-9455, Revision 4, Tennessee Valley Authority Watts Bar Unit No. 2 Reactor Vessel Radiation Surveillance Program, August 2019.

C-3 Westinghouse Report WCAP-9455, Revision 2, Tennessee Valley Authority Watts Bar Unit No. 2 Reactor Vessel Radiation Surveillance Program, June 1995.

WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-3 CVGRAPH VERSION 6.02 INDIVIDUAL PLOTS OF UNIRRADIATED SPECIMENS WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-4 Un irradiated Intermediate Shell Forging 05 (Tangential)

CY Graph 6.02 : Hyperbolic Ta ngent Curve Printed on 1/9/2020 11 :28 AM A = 88.60 B = 86.40 C = 61.94 TO = 8.85 D = 0.00 Correlation Coefficient = 0.943 Equation is A + B * (Tanh((T-TO)/(C+ DT))j Upper Shelf Energy = 175.00 (Fixed ) Lower Shelf Energy= 2.20 (Fixed)

Temp@30 ft -lbs=-42 .30° F Temp <. 35 ft-lbs=-36.00° F Te mp@50 ft-lbs= -20.90° F Plant: Watts Bar 2 Material SA508CL2 Heat: 527828 Orielllation: Tan gential Capsule: Unirrad Fluence: O.OOE+oOO n/cm 2 200 --

180 . . . . .

- Vo 160 / B

-- r,:;

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~

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El 0

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20

. / (~

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-300 -200 -100 0 100 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-5 Plant: Watts Bar 2 Materia l: SA508CL2 Heat 527828 Orientation: Tangential Capsule: Unirrad Fluence: O.OOE+OOO n/cm 2 Unirradiated Intermediate Shell Forging 05 (Tangential)

Charpy V-Notch Data Temperature{° F) InputCVN Computed CVN Differential

-1 *o 2.0 3.2 -1.22

-1 50 3.0 3.2 -0.22

-75 6.0 13.0 -7.0 1

-7 5.0 13.0 -8.01

-40 10.0 31.8 -2 1.78

-40 78.0 31.8 46.22

-25 12.0 45 .6 -33.59

-1 0 71.0 63.1 7.91 0 11 6.0 763 39.66 0 30.0 763 -46.34 25 127.0 110.6 16.36 25 123.0 110.6 12.36 74 13 .0 156.2 -21.21 74 146.0 l 6.2 -1 0.21 12 5 166.0 171.0 -5.03 2 10 200.0 174.7 25.26 2 10 165.0 174.7 -9.74 2 10 169.0 174.7 -5.74 CVGraph 602 01 /09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-6 Unirradiated Intermediate Shell Forging 05 (Tangential)

CY Graph 6.02 : Hyperbolic Ta ngent Curve Printed on 1/9/2020 11 :3 1 AM A = 46.34 B = 45.34 C = 44.30 TO = -9.39 D = 0.00 Co rrelation Coefficient = 0.92 1 Equation is A + B * (Tanh((T-TO)/(C+ DT))j Upper She lf L.E. = 9 1.68 Lower Shelf L.E. = 1.00 (Fixed)

Te mp ~5 mil s=-20.70° F Plant: Watts Ba r 2 Mate rial SA508CL2 Hea t: 527828 O rielllation: Tan gential Capsule : Un irrad Fluence: O.OOE+oOO n/cm 2 80

  • --e-( IJ 70
  • -==

Q 60

( IJ

~ 50 Q.,.

~

~

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40

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20 0 l::::::::::c::+/-::::::::fit:::l..OL&....--1._L....-.l,_.....1....__.L_.1....-...L.....L.._J_..1...-....L--1..__J

-300 -200 -100 0 100 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-7 Plant: Watts Bar 2 Materia l: SA508CL2 Heat 527828 Orientation: Tangential Capsule: Unirrad Fluence: O.OOE+OOO n/cm 2 Unirradiated Intermediate Shell Forging 05 (Tangential)

Charpy V-Notch Data Temperature{° F) Input L. E. Computed L. E. Differential

-1 *o 2.0 1.2 0.84

-1 50 1.0 1.2 -0.16

-75 1.0 5.5 -4.46

-7 1.0 5. -4.46

-40 .0 19.2 -1 4.20

-40 58.0 19.2 38.80

-25 9.0 31.0 -22.00

-1 0 54.0 45.7 8.28 0 79.0 55.8 23. 19 0 24.0 55.8 -3 1.8 1 25 83.0 75.8 7. 16 25 79.0 75.8 3. 16 74 81.0 89.6 -8.63 74 9 1.0 89.6 1.37 125 93.0 91.5 1.53 2 10 94.0 9 1.7 2.32 2 10 90.0 91.7 -1.68 2 10 92.0 9 1.7 0.32 CVGraph 6.02 01 /09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-8 Un irradiated Intermediate Shell Forging 05 (Tangential)

CY Graph 6.02 : Hyperbolic Tangent Curve Printed on 1/9/2020 11 :33 AM A= 50.00 B = 50.00 C = 83.46 TO= 21.98 D = 0.00 Correlation Coefficient = 0.982 Equation is A + B * (Tanh((T-TO)/(C+ DT))j Upper Shelf%Shear = 100.00 (Fixed) Lower Shelf %Shear = 0.00 (Fixed)

Temperature at 50% Shear = 22 .00 Plant: Watts Bar 2 Material SA508CL2 Heat: 527828 Orielllation: Tan ge ntial Capsule: Unirrad Fluence: O.OOE+oOO n/cm 2 100 90 . .

/-

I 80 J

~

70

~

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- I QJ

~

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-300 -200 -100 0 100 200 300 400 soo 600 Temperature {° F)

CVGraph 6.02 01/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-9 Plant: Watts Bar 2 Materia l: SA508CL2 Heat 527828 Orientation: Tangential Capsule: Unirrad Fluence: O.OOE+OOO n/cm 2 Unirradiated Intermediate Shell Forging 05 (Tangential)

Charpy V-Notch Data Temperature{° F) Input %Shear Computed %Shear Differential

-1 *o *_o 16 3.40

-1 50 5.0 1.6 3.40

-75 9.0 8.9 0.08

-7 9.0 8.9 0.08

-40 14.0 18. -4.46

-40 28.0 18.5 9.54

-25 13.0 24.5 -1 1.49

-1 0 30.0 31.7 -1.73 0 52.0 37 .1 14.87 0 25.0 37 .1 -1 2. 13 25 58.0 51.8 6. 19 25 55.0 51.8 3. 19 74 71.0 77.7 -6.67 74 73.0 77.7 -4.67 125 100.0 92.2 7.81 2 10 100.0 98.9 1.09 2 10 100.0 98.9 1.09 2 10 100.0 98.9 1.09 CVGraph 6 02 01 /09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-10

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Westinghouse Non-Proprietary Class 3 C-11

  • Legibility for this test temperature is not clear. It could be 0°F rather than the -100°F shown here.

Using -100°F is consistent with WCAP-9455, Rev. 4 and conservative, providing a larger T30 shift. This may be revisited, if necessary, during a future evaluation, e.g. next tested capsules credibility evaluation.

WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-12

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-13

  • Legibility for this test temperature is not clear. It could be 0°F rather than the -100°F shown here.

Using -100°F is consistent with WCAP-9455, Rev. 4 and conservative, providing a larger T30 shift. This may be revisited, if necessary, during future evaluation, e.g. next tested capsules credibility evaluation.

WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-14

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-15

  • Legibility for this test temperature is not clear. It could be 0°F rather than the -100°F shown here.

Using -100°F is consistent with WCAP-9455, Rev. 4 and conservative, providing a larger T30 shift. This may be revisited, if necessary, during future evaluation, e.g. next tested capsules credibility evaluation.

WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-16 Unirradiated Surveillance Program Weld Metal CVGraph 6.02 : Hyperbolic Tangent Cwve Printed on 1/9/2020 11:41 AM A= 73.10 B = 70.90 C = 104.77 TO= 16.13 D = 0.00 Correlation Coefficient = 0.987 Equation is A+ B * [Tanh((T-TO)/(C+DT))j Upper Shelf Energy= 144.00 (Fixed) Lower Shelf Energy= 2.20 (Fixed)

Tcmp@30 ft-lbs=-57 .70° F Temp@35 ft-lbs=-46.70° F Tcmp@50 ft-lbs=-19.20° F Plant: Watts Bar 2 Material: SAW Heat: 895075 Orientation: NA Capsule: Unin-ad Fluence: O.OOE+oOOn/cm2 120

--tl.J

.c 100 I

~

Oil

.. 80

~

~

=

z 60 u

40 0 ............_ ......._ ........._,__......._ ......._ _.__,__......._ ......._____,__......._ ......._ _.__,____.,_.....

-300 -200 -100 0 100 200 300 400 500 600 Temperature (° F)

CVGraph 6.02 01/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-17 Plant: Watts Bar 2 Material: SAW Heat 895075 Orientation: A Capsule: Unirrad Fluence: O.OOE+OOO n/cm 2 U nirradiated Surveillance Program Weld Metal Charpy V-Notch Data Temperature{° F) InputCVN Computed CVN Differential

-1 *o 4.5 7.9 -3.4 1

-1 50 3.5 7.9 -4.4 1

-1 50 3.0 7.9 -4. 9 1

-7 30.0 23.4 6.62

-75 33.5 23.4 10.12

-16 43.0 52 .0 -9.02

-16 34.0 52.0 -1 8.02

-1 6 59.0 52.0 6.98 25 82.0 79.1 2.9 1 50 105.0 953 9.74 50 104.0 95.3 8.74 100 l 18.0 120.2 -2.20 12 12 .0 128.2 -3.23 12 112.0 128.2 -16.23 2 10 139.0 140 .6 -1.58 2 10 154.0 140.6 13.42 2 10 140.0 140 .6 -0.58 250 143.0 142.4 0.6 1 CVGraph 6 02 01 /09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-18 Unirrad iated Surveillance Program Weld Metal CVGraph 6.02 : Hyperbolic Ta ngent Curve Pri nted on 1/9/2020 11 :43 AM A= 47.66 B = 46.66 C = 78.92 TO= -2.74 D = 0.00 Co rrelation Coeffi cient = 0.990 Equation is A + B * [Ta nh((T-TO)/(C+DT)))

Upper She lf LE.= 94.32 Lower Shelf LE.= 1.00 (Fixed)

Temp 5 mils=-24.70° F Plant: Watts Ba r 2 Material: SAW Heat: 895075 Orientation: NA Capsule: Un irrad Fluence: O.OO E+oOO n/cm 2 100 90 80

  • --e-c ,J 70
  • -==

Q 60 c ,J

~ 50 c..

~

~

~

i..

~

40

~ 30

~

20 10 0 l:::::::::::::i:::::::::t::=o_J_.1....-...L.....i....---1__j~.L_....i.........L----1._L_...i...._...L__i__J

-300 -200 -100 0 100 200 300 400 500 600 Temperature {° F)

CYGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-19 Plant: Watts Bar 2 Material: SAW Heat 895075 Orientation: A Capsule: Unirrad Fluence: O.OOE+OOO n/cm 2 U nirradiated Surveillance Program Weld Metal Charpy V-Notch Data Temperature{° F) InputL. E. Computed L. E. Differential

-1 *o 1.0 3 .2 -2.18

-1 50 1.0 3.2 -2. 18

-1 50 0.5 3.2 -2.68

-7 21.0 13.9 7.11

-75 23.0 13.9 9.11

- 16 34.0 39.9 -5.89

- 16 28.0 39.9 -1 1.89

-1 6 43.0 39.9 3. 11 25 65.0 63.4 1.58 50 77.0 74.9 2. 10 50 83.0 74.9 8. 10 100 88.0 87.9 0. 11 12 9 1.0 90.8 0.21 12 84.0 90.8 -6.79 2 10 94.0 93.9 0.10 2 10 96.0 93.9 2.10 2 10 9 1.0 93.9 -2.90 250 96.0 94.2 1.83 CVGraph 6.02 01 /09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-20 Unirradiated Surveillance Program Weld Metal CY Graph 6.02 : Hyperbolic Ta ngent Curve Printed on 1/9/2020 11 :44 AM A= 50.00 B = 50.00 C = 110.15 TO= 0.36 D = 0.00 Correlation Coefficient = 0.989 Equation is A + B * (Tanh((T-TO)/(C+ DT))j Upper Shelf % Shear = 100.00 (Fixed) Lower Shelf % Shear = 0.00 (Fixed)

Temperature at 50% Shear = 0.40 Plant: Watts Bar 2 Material: SAW Hea t: 895075 Orielllation: NA Capsule : Unirrad Fluence: O.OOE+oOO n/cm 2 100 -

90 . .

v-

/ . .

80 I I 0 70

~

QJ f

r

.c 60 00 c:: so QJ

~

~

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~

30

  • {

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- ,I) 10 . I . . . .

0

-300

-- ~

-200 I

-100 I

0 I

100 I

200 I

300 I

400 I

soo I

600 Temperature {° F)

CVGraph 6.02 01/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-21 Plant: Watts Bar 2 Material: SAW Heat 895075 Orientation: A Capsule: Unirrad Fluence: O.OOE+OOO n/cm 2 U nirradiated Surveillance Program Weld Metal Charpy V-Notch Data Temperature{° F) Input %Shear Computed %Shear Differential

-1 *o *_o 6.1 -1.12

-1 50 5.0 6.1 -1.12

-1 50 5.0 6.1 -1.12

-7 18.0 20.3 -2.29

-75 2 .0 20.3 4.7 1

- 16 43.0 42.6 0.37

-16 40.0 42.6 -2.63

-1 6 45.0 42.6 2.37 25 60.0 61.0 -1.00 50 70.0 71.1 -1.12 50 70.0 71 I -1.12 100 100.0 85.9 14.07 12 90.0 90.6 -0.58 12 7 .0 90.6 -1 .58 2 10 100.0 97. 8 2.17 2 10 100.0 97. 8 2.17 2 10 100.0 97. 8 2.17 250 100.0 98.9 1.06 CVGraph 6.02 01 /09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-22 Unirradiated Heat-Affected Zone (HAZ)

CVGraph 6.02 : Hyperbolic Tangent Cwve Printed on 1/9/2020 11:45 AM A = 66.10 B = 63.90 C = 53.13 TO = -67.87 D = 0.00 Correlation Coefficient = 0.960 Equation is A+ B * [Tanh((T-TO)/(C+DT))j Upper Shelf Energy= 130.00 (Fixed) Lower Shelf Energy= 2.20 (Fixed)

Tcmp@30 ft-lbs=-101.80° F Temp@35 ft-lbs=-96. 10° F Tcmp@50 ft-lbs=-81.50° F Plant: Watts Bar 2 Material: SA508CI2 Heat: 527828 Orientation: NA Capsule: Unin-ad Fluence: O.OOE+oOO n/cm2 120

--tl.J

.c 100 I

~

Oil

.. 80

~

~

=

z 60 u

40 0 t:=:::c:::t:::......i.._J_.1....--...L.....i_-1..__j"-l._....i__J____,J,,_L_..i..._...L__,i__J

-300 -200 -100 0 100 200 300 400 500 600 Temperature (° F)

CVGraph 6.02 01/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-23 Plant: Watts Bar 2 Material SA508Cl2 Heat: 527828 Orientation: I A Capsule: Unirrad Flucnc c: O.OOE+OOO n/cm' U nirradiated Heat-Affected Zone (HAZ)

Charpy V-Notch Data Temperature{° F) Input CV Computed CVN Differential

-184 8.0 3.8 4.21

-1 84 6.5 3.8 2.7 1

-1 84 8.0 3.8 4.2 1

-125 11.0 1 .5 -4.53

-12 11.0 l .5 -4.53

-90 50.0 40.9 9.08

-75 36.5 57.6 -21.08

-75 90.0 57.6 32.42

-50 76.0 86.8 -1 0.82

-50 69.0 86.8 -17.82

-7 152.0 118.3 33.73

-7 114.0 118.3 -4.27

-7 118.0 118. -0.27 100 111.0 129. 8 -1 8.77 100 136.0 129.8 6.23 210 126.0 130.0 -4.00 210 13 1.0 130.0 1.00 2 10 125.0 130.0 -5.00 CVGraph 6.02 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-24 Unirradiated Heat-Affected Zone (HAZ)

CY Graph 6.02 : Hyperbolic Ta ngent Curve Printed on 1/9/2020 11 :46 AM A= 39.49 B = 38.49 C = 49.67 TO= -63.96 D = 0.00 Co rrelation Coefficient = 0.979 Equation is A + B * (Tanh((T-TO)/(C+ DT))j Upper She lf L.E. = 77.97 Lower Shelf L.E. = 1.00 (Fixed)

Te mp ~5 mil s=-69.70° F Plant: Watts Ba r 2 Mate rial: SA508C l2 Hea t: 527828 O rielllation: NA Capsule : Un ir r ad Fluence: O.OOE+oOO n/cm 2 90 80

--....e 1'J 70

....= so 0

60 1'J

=

=

Q..

~

40

-=

~

i...

~

...- 30

~=

20 0 t:::::::::i:==ts:L..J~.L,_....1...---1_.1.....-...L.....L.._JL_...1...-....L----1._L_....L...--1.-L........J

-300 -200 -100 0 100 200 300 400 500 600 Temperature (° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-25 Plant: Watts Bar 2 :tvfaterial SA508Cl2 Heat: 527828 Orientation: NA Capsule: U nirrad Fluence: O.OOE+OOO n/cm 1 U nirradiated Heat-Affected Zone (HAZ)

Charpy V-Notch Data Temperature (0 F) Input L. E. Computed L. E. Differential

-184 3.0 1.6 1.39

-1 84 1.0 1.6 -0.6 1

-1 84 1.0 1.6 -0.6 1

- 12 2.0 7.1 - .07

-12 3.0 7.1 -4.07

-90 26.0 21.0 5.02

-75 2 1.0 31 I -1 0.07

-75 49.0 31.1 17.93

-50 45.0 50.0 -5.03

-50 42.0 50.0 -8.03

-7 80.0 70.9 9.08

-7 74.0 70.9 3.08

-7 69.0 70.9 -1 .92 100 70.0 77.9 -7.87 100 8 1.0 77.9 3.13 2 10 77.0 78.0 -0.97 2 10 79.0 78.0 1.03 2 10 78.0 78.0 0.03 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-26 U nirradiated Heat-Affected Zone (HAZ)

CVGraph 6.02 : Hyperbolic Ta ngent Curve Printed on 1/9/2020 11 :47 AM A = 50.00 B = 50.00 C = 65.42 TO = -60.30 D = 0.00 Correlation Coeffi cient = 0.983 Equation is A + B * [Ta nh((T-TO)/(C+DT)))

Upper Shelf %Shea r = 100.00 (Fixed) Lower Shelf 'YoShear = 0.00 (Fixed)

Temperature at 50% Shear = -60.20 Plant : Watts Bar 2 Material: SA508C l2 Heat: 527828 Orientation: NA Capsule: Un irrad Fluence: O.OO E+oOO n/cm 2 JOO i 90  :

I

/  :  :  :

- j 80 ' '  :  : '

/c ' ' ' '

70

-I i..

~

~

.c 60 00 I

_j_

C 50 ' ' ' ' '

~

C.J i..

~

_7- ' ' ' ' '

40 '

-p ' ' ' ' '

~

30

- I 20 JO

I  :

- ~o I I I I 0

-300 -200 -JOO 0 JOO 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-27 Plant: Watts Bar 2 :tvfaterial SA508Cl2 Heat: 527828 Orientation: NA Capsule: U nirrad F luence: O.OOE+OOO n/cm 1 U nirradiated Heat-Affected Zone (HAZ)

Charpy V-Notch Data Temperature (0 F) Input %Shear Computed %Shear Differential

-184 7.0 2.2 4.77

-1 84 7.0 2.2 4.77

-1 84 7.0 2.2 4.77

- 12 .0 12.2 -7.15

-12 .0 12.2 -7.15

-90 40.0 28 .7 11.26

-75 34.0 39 .0 -4.95

-75 50.0 39.0 11.05

-50 50.0 57. 8 -7.81

-50 50.0 57. 8 -7.81

-7 100.0 83.6 16.39

-7 75.0 83.6 -8.6 1

-7 8 .0 83 .6 1.~9 100 100.0 99.3 0. 74 100 100.0 99.3 0. 74 2 10 100.0 100.0 0.03 2 10 100.0 100.0 0.03 2 10 100.0 100.0 0.03 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-28 CVGRAPH VERSION 6.02 INDIVIDUAL PLOTS OF CAPSULE U SPECIMENS WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-29 Capsule U Intermediate Shell Forging 05 (Tangential)

CVGraph 6.02: Hyperbolic Tangent Curve Printed on 1/9/2020 11:49 AM A= 66.10 B = 63.90 C = 74.07 TO= 31. 76 D = 0.00 Correlation Coefficient = 0.988 Equation is A+ B

  • ITanh((T-TO)/(C+DT))I Upper Shelf Enefh'Y = 130.00 (fixed) Lower Shelf E nerh'Y = 2.20 (Fixed)

Temp:q)O ft-lbs =-15 .60° F Temp@J5 ft-lbs= -7.60° F Temp@50 ft-lbs= I 2.70° F Plant : Watts Bar 2 Material: SA508CI2 Heat: 527828 Orientation: Tangential Capsule: U Fluence : 6.04E+018 n/cm 2 VJ

~

100 I

~

... 80 Of) lo.

Qj

=

~ 60

z u>

40 o--------------------------------

-300 -200 -100 0 100 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 01 /09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-30 Plant: Watts Bar 2 :tvfaterial SA508CI2 Heat: 527828 Orientation: Ta ngential Capsule: U Fluence: 6.04E+018 n/cm 1 Capsule U Intermediate Shell Forging 05 (Tangential)

Charpy V-Notch Data Temperature (0 F) Input CV Computed CV Differential

-60 8.0 12.1 -4.10

-50 2 1.0 14.9 6. 14

-30 32.0 22.S 9. 5 1

-20 21.0 27. -6. 3

-1 28.0 304 -2.~8

-1 0 26.0 33 .5 -7.46

-5 42.0 36.8 5.24 0 48.0 40.3 7.74 10 52.0 47. 8 4.15 40 57.0 73.2 -1 6.18 75 106.0 99.7 6.33 120 1240 119.2 4.80 170 130.0 1270 2.99 200 138.0 128. 7 9. 5 220 130.0 129.2 0.79 CVGraph 602 0 1/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-31 Capsule U Intermediate Shell Forging 05 (Tangential)

CVGraph 6.02 : Hyperbolic Ta ngent Curve Printed on 1/9/2020 11 :50 AM A = 44. 76 B = 43. 76 C = 75.61 TO = 26.23 D = 0.00 Correlation Coeffi cient = 0.987 Equation is A + B * [Ta nh((T-TO)/(C+DT)))

Upper She lf LE. = 88.51 Lower Shelf L.E. = 1.00 (Fixed)

Temp 5 mils= 9.10° F Plant : Watts Bar 2 Material: SA508C l2 Heat: 527828 Orientation: Tan gential Capsule: U fluence: 6.04 E+o18 n/cm 2 90 80

  • --e-

"1 70

'-' 60

=

  • - 0 "1

= 50

~

~

~

~

~

1-

~

40 30

~

~

20 10 0

-300 -200 -100 0 100 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-32 Plant: Watts Bar 2 :tvfaterial SA508CI2 Heat: 527828 Orientation: Tangential Capsule: U F luence: 6.04E+018 n/cm 1 Capsule U Intermediate Shell Forging 05 (Tangential)

Charpy V-Notch Data Temperat ure (0 F) Input L. E. Computed L. E. Differential

-60 6.0 9. 1 -3.1 1

-50 14.0 113 2.72

-30 22.0 17. 1 4.87

-20 18.0 20.9 -2.90

-1 21.0 23 .0 -2.0 1

-1 0 19.0 25 .3 -6.26

-5 33.0 27.6 5.36 0 34.0 30 .2 3.84 10 39.0 35.5 3.49 40 42.0 52.6 -10.64 75 75.0 69.6 5.37 120 86.0 81.8 4.24 170 8 .0 86.6 -3.61 200 90.0 87.6 2.~6 220 85.0 88.0 -3.00 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-33 Capsule U Intermediate Shell Forging 05 (Tangential)

CVGraph 6.02 : Hyperbolic Ta ngent Curve Printed on 1/9/2020 11 :5 1 AM A = 50.00 B = 50.00 C = 66.36 TO = 46.69 D = 0.00 Correlation Coeffi cient = 0.994 Equation is A + B * [Ta nh((T-TO)/(C+DT)))

Upper Shelf %Shea r = 100.00 (Fixed) Lower Shelf 'YoShear = 0.00 (Fixed)

Temperature at 50% Shear = 46.70 Plant : Watts Bar 2 Material: SA508C l2 Heat: 527828 Orientation: Tan gential Capsule: U Fluence: 6.04 E+o18 n/cm 2 JOO i 90  : /  :  :

- I

  • 1 J

80 '  :  : '

70 i..

~

~

.c 60 r 00 C

~

50 ' f ' ' '

I C.J i.. -

~ ' '

40 ' ' '

~

30

- /o

- cp 20 -

JO

_j  :

0 7 I I I

-300 -200 -JOO 0 JOO 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-34 Plant: Watts Bar 2 :tvfaterial SA508CI2 Heat: 527828 Orientation: Tangential Capsule: U Fluence: 6.04E+018 n/cm 1 Capsule U Intermediate Shell Forging 05 (Tangential)

Charpy V-Notch Data Temperature (0 F) Input %Shear Computed %Shear Differential

-60 5.0 3.9 1.14

-50 10.0 5.1 4.85

-30 10.0 9 .0 0.98

-20 10.0 11.8 -1. 82

-1 1 .0 13 . I. 2

-1 0 15.0 15.3 -0.33

-5 20.0 17.4 2.6 1 0 25.0 19 .7 5.33 10 25.0 24.9 0. 13 40 35.0 45.0 -9.98 75 70.0 70.1 -0. 12 120 100.0 90.1 9.89 170 100.0 97.6 2. 7 200 100.0 99.0 0.98 220 100.0 99. 5 0. 54 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-35 Capsule U Intermediate Shell Forging 05 (Axial)

CVGraph 6.02: Hyperbolic Tangent Curve Printed on 1/9/2020 11:52 AM A= 53.60 B = 51.40 C = 104.98 TO = 31.50 D = 0.00 Correlation Coefficient= 0.974 Equation is A+ B * [Tanh((T-TO)/(C+DT)) I Upper Shelf Energy= 105.00 (Fixed) Lower Shelf Energy= 2.20 (Fixed)

Temp@30 ft-lbs=-20.50° F Temp@35 ft-lbs= -8.20° F Temp@50 ft-lbs= 24.20° F Plant: Watts Bar 2 Material: SA508CL2 Heat: 527828 Orientation: Axial Capsule: U Fluence: 6.04E+o18 n/cm*

--r:,J

,.Q

~

I 80 QIJ i.. 60

~

~

=

z u 40 o------------------------------------

-300 -200 -100 0 100 200 300 400 500 600 Temperature (° F)

CVGraph 6.02 01/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-36 Plant: Watts Bar 2 Material: SAS08CL2 Heat: 527828 Orientation: xial Capsule: U Fluence: 6.04E+018 n/cm 1 Capsule U Intermediate Shell Forging 05 (Axial)

Charpy V-Notch Data Temperature (0 F) Input CV Computed CV D ifferential

-60 14.0 17 .5 -3.5 1

-50 22.0 20.2 1.84

-35 10.0 24.8 -14.79

-30 31.0 26. 4.48

-20 39.0 30.2 8.77

-1 5 29.0 32.2 -3.2 1

-1 0 27.0 34.3 -7.28 0 41. 0 38.6 2.38 10 49.0 43 .2 5.78 30 6 1.0 52.9 8. 14 75 730 73.8 -0.76 120 74.0 88.9 - 14.93 170 102.0 98.1 3.86 200 109.0 101.0 7.99 220 103.0 102.2 0. 76 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-37 Capsule U Intermediate Shell Forging 05 (Axial)

CVGraph 6.02 : Hyperbolic Ta ngent Curve Printed on 1/9/2020 11 :54 AM A= 38.73 B = 37.73 C = 96.58 TO= 24.51 D = 0.00 Correlation Coeffi cient = 0.978 Equation is A + B * [Ta nh((T-TO)/(C+DT)))

Upper She lf LE = 76.47 Lower Shelf L.E. = 1.00 (Fixed)

Temp@35 mils= 15.00° F Plant: Watts Ba r 2 Material: SA508CL2 Heat: 527828 Orientation: Axial Capsule: U Fluence: 6.04 E+o18 n/cm 2 70

  • --e-

"1 60

= 50

  • - 0 "1

=

~

~ 40

~

~

~

1-

~

30

~

~

20 o l::=::::c=:::t::::....a....---1..----1._L..L...-...L.....i....---1..___i._L_..i...._...L.....i....---1..----1._J

-300 -200 -100 0 100 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-38 Plant: Watts Bar 2 Materia l: SAS08CL2 Heat: 527828 Orientation: xial Capsule: U Fluence: 6.04E+018 n/cm 1 Capsule U Intermediate Shell Forging 05 (Axial)

Charpy V-Notch Data Temperature (0 F) Input L. E. Computed L. E. Differential

-60 9.0 12 .2 -3. 17

-50 14.0 14.3 -0.29

-35 10.0 18.0 -8.04

-30 22.0 19.4 2. 6

-20 28.0 22. . 2

-15 2 1.0 24.1 -3. 10

-1 0 2 1.0 25 .8 -4.79 0 29.0 29.4 -0. 36 10 39.0 33.1 5.90 30 49.0 40.9 8. 13 75 54.0 56.8 -2. 84 120 58.0 67.3 -9.29 170 7 .0 72.9 0.07 200 76.0 74. 5 1.48 220 80.0 75 .2 4.83 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-39 Capsule U Intermediate Shell Forging 05 (Axial)

CVGraph 6.02 : Hyperbolic Tangent Curve Printed on 1/9/2020 11 :55 AM A= 50.00 B = 50.00 C = 97.89 TO= 69.10 D = 0.00 Correlation Coefficient = 0.986 Equation is A + B * [Tanh((T-TO)/(C+DT)))

Upper Shelf %Shear = 100.00 (Fixed) Lower Shelf 'YoShear = 0.00 (Fixed)

Temperature at 50% Shear = 69. lO Plant: Watts Bar 2 Material : SA508CL2 Heat: 527828 Orientation: Axial Capsule: U Fluence: 6.04E+o18 n/cm 2 JOO i

-- ~ -

90  : /  :  :

80 I  : '

70 I

/. ' '

i..

~

~

.c 60 J -

00 C

~

50 '

1 '

~

C.J i..

~

40

' I ' ' ' '

30 9:

20 I-

- _o~ ~

JO 0

- __.,,,. 7 I I I

-300 -200 -JOO 0 JOO 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-40 Plant: Watts Bar 2 Materia l: SAS08CL2 Heat: 527828 Orientation: xial Capsule: U Fluence: 6.04E+018 n/cm 1 Capsule U Intermediate Shell Forging 05 (Axial)

Charpy V-Notch Data Temperature (0 F) Input %Shear Computed %Shear Differential

-60 10.0 6. 7 3.33

-50 15.0 8.1 6.93

-35 10.0 10.6 -0.65

-30 l .0 11.7 3.34

-20 1 .0 13.9 1.06

-15 15.0 15.2 -0.2 1

-1 0 15.0 16 .6 -1.57 0 15.0 19.6 -4.59 10 20.0 23.0 -3.01 30 35.0 31.0 3.98 75 55.0 53.0 1.99 120 60.0 73.9 -13.88 170 100.0 88 .7 11.29 200 100.0 93 .5 6.45 220 100.0 95.6 4.38 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-41 Capsule U Surveillance Program Weld Metal CVGraph 6.02: Hyperbolic Tangent Curve Printed on 1/9/2020 11:56 AM A= 68.60 B = 66.40 C = 104.80 TO = 44.44 D = 0.00 Correlation Coefficient= 0.967 Equation is A+ B * [Tanh((T-TO)/(C+DT)) I Upper Shelf Energy= 135.00 (Fixed) Lower Shelf Energy= 2.20 (Fixed)

Tcmp@30 ft-lbs=-25 .10° F Tcmp@35 ft-lbs=-13.90° F Temp@50 ft-lbs= 14.30° F Plant: Watts Bar 2 Material: SAW Heat: 895075 Orientation: NA Capsule: U Fluence: 6.04E+o18 n/cm*

120

~

r:,J

,.Q I 100 QIJ i.. 80

~

~

=

z 60 u

40 o------------------------------------

-300 -200 -100 0 100 200 300 400 500 600 Temperature (° F)

CVGraph 6.02 01/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-42 Plant: Watts Bar 2 Material: SAW Heat: 895075 Orientation: NA Capsule: U F luence: 6.04E+018 n/cm 1 Capsule U Surveillance Program Weld Metal Charpy V-Notch Data Temperature (0 F) Input CV Computed CV Differential

-60 21.0 18.1 2.87

-50 20.0 21.0 - 1.00

-30 2 1.0 28 .0 -7. 04

-2 23.0 30.1 -7.08

-20 26.0 32.2 -6.24

-1 5 50.0 34.5 15.48

-1 0 39.0 36.9 2.09 0 38.0 42.0 -4.02 10 52.0 47. 5 4.47 60 68.0 78.4 -1 0.39 75 110.0 87.4 22.57 120 86.0 109.6 -23.6 1 170 12 .0 123.9 -0.92 200 138.0 128.5 9.49 220 143.0 130. 5 12.50 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-43 Ca psule U Surveillance Program Weld Metal CVGraph 6.02 : Hyperbolic Ta ngent Curve Printed on 1/9/2020 11 :57 AM A= 44.88 B = 43.88 C = 98.10 TO= 26.09 D = 0.00 Correlation Coeffi cient = 0.980 Equation is A + B * [Ta nh((T-TO)/(C+DT)))

Upper She lf LE. = 88.76 Lower Shelf L.E. = 1.00 (Fixed)

Temp 5 mils= 3.70° F Plant: Watts Ba r 2 Material: SAW Heat: 895075 Orientation: NA Capsule: U fluence: 6.04 E+o18 n/cm 2 90 80

  • --e-

"1 70

'-' 60

=

  • - 0 "1

= 50

~

~

~

~

~

1-

~

40 30

~

~

20 10 0

-300 -200 -100 0 100 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-44 Plant: Watts Bar 2 Material: SAW Heat: 895075 Orientation: NA Capsule: U Fluence: 6.04E+018 n/cm 1 Capsule U Surveillance Program Weld Metal Charpy V-Notch Data Temperat ure (0 F) Input L. E. Computed L. E. Differential

-60 17.0 13.9 3.06

-50 16.0 16.3 -0.35

-30 17.0 22.2 -5.2 1

-2 21.0 23.9 -2.89

-20 23.0 2 .7 -2.66

-15 38.0 27.5 10.5 0

-1 0 28.0 29.4 -1.43 0 29.0 33.5 -4.48 10 42.0 37.7 4.25 60 52.0 59.5 -7.47 75 76.0 65.1 10.89 120 71.0 775 -6.48 170 84.0 84.3 -0. 3 200 90.0 86.3 .70 220 86.0 87 .1 -1.1 1 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-45 Capsule U Surveillance Program Weld Metal CVGraph 6.02 : Hyperbolic Tangent Curve Printed on 1/9/2020 I 1:58 AM A= 50.00 B = 50.00 C = 134.87 TO= 26.42 D = 0.00 Correlation Coefficient = 0.955 Equation is A + B * [Tanh((T-TO)/(C+DT)))

Upper Shelf % Shear = 100.00 (Fixed) Lower Shelf 'YoShear = 0.00 (Fixed)

Temperature at 50% Shear = 26.50 Plant: Watts Bar 2 Material: SAW Heat: 895075 Orientation: NA Capsule: U Fluence: 6.04E+o18 n/cm 2 JOO i

-- ~ - '

/  :  :

90

-- I /

80 '  : '

70 ' ' I ' ' '

i..

~

~

.c 60 t/ --

00 C

~

50 '

/o ' ' '

C.J i.. - 0

~

~

40 '

30

- o} ~

- cf 20

/  :

JO 0

- .,_.,.,.,,. / I I I I

-300 -200 -JOO 0 JOO 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-46 Plant: Watts Bar 2 Material: SAW Heat: 895075 Orientation: NA Capsule: U F luence: 6.04E+018 n/cm 1 Capsule U Surveillance Program Weld Metal Charpy V-Notch Data Temperature (0 F) Input %Shear Computed %Shear Differential

-60 25.0 21.7 3.27

-50 20.0 24.4 -4.36

-30 35.0 30.2 4.78

-2 30.0 31.8 -1.8 1

-20 30.0 33.4 - .44

-1 5 45.0 35. 1 9.89

-1 0 40.0 36.8 3.18 0 35.0 40. 3 -5.33 10 40.0 43.9 -3.94 60 55.0 62.2 -7.20 75 80.0 67.3 12.73 120 60.0 80.0 -20.02 170 100.0 89.4 10.63 200 100.0 929 7.08 220 100.0 94.6 5.36 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-47 Capsule U Heat-Affected Zone (HAZ)

CVGraph 6.02: Hyperbolic Tangent Curve Printed on 1/9/2020 11:59 AM A = 60.10 B = 57.90 C = 104.39 TO = -43.34 D = 0.00 Correlation Coefficient= 0.931 Equation is A+ B * [Tanh((T-TO)/(C+DT)) I Upper Shelf Energy= 118.00 (Fixed) Lower Shelf Energy= 2.20 (Fixed)

Temp@30 ft-lbs=-103 .40° F Temp@35 ft -lbs=-9 1.70° F Temp@50 ft -lbs=-61.70° F Plant: Watts Bar 2 Material: SA508CL2 Heat: 527828 Orientation: NA Capsule: U Fluence: 6.04E+o1 8 n/cm*

--r:,J

,.Q

~

I 100

._., 80 QIJ i..

~

~

= 60 z

u 40 o------------------------------------

-300 -200 -100 0 100 200 300 400 500 600 Temperature (° F)

CVGraph 6.02 01/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-48 Plant: Watts Bar 2 Material: SAS08CL2 Heat: 527828 Orientation: NA Capsule: U Fluence: 6.04E+018 n/cm 1 Capsule U Heat-Affected Zone (HAZ)

Charpy V-Notch Data Temperature (0 F) Input CV Computed CV D ifferential

- 115 29.0 25.6 3.39

- 110 42.0 27.4 14.55

-1 00 14.0 31.4 -17.43

-90 39.0 3 .8 3.18

-80 33.0 40 .6 -7. 6

-70 63.0 45.6 17.37

-60 52.0 50.9 1.06

-35 77.0 64.7 12.29

-30 33.0 67. 5 -34.46

-20 71.0 72.8 -1.83 IO 98.0 87.4 10.65 75 117.0 107 .1 9.87 1 0 10 .0 11 .2 - 10.22 200 12 .0 116.9 8.08 220 127.0 117.3 9.74 CVGraph 602 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-49 Capsule U Heat-Affected Zone (HAZ)

CVGraph 6.02: Hyperbolic Tangent Curve Printed on 1/9/2020 12:02 PM A= 37.98 B = 36.98 C = 109.83 TO = -37.27 D = 0.00 Correlation Coefficient= 0.956 Equation is A + B * [Tanh((T-TO)/(C+DT)) I Upper ShelfL.E. = 74.97 Lower ShelfL.E. = l.00 (Fixed)

Temp@3 5 mils=-46.10° F Plant: Watts Bar 2 Material: SA508CL2 Heat: 527828 Orientation: NA Capsule: U Fluence: 6.04E+o18 n/cm*

80 70

--eVJ 60 50

.....=

Q VJ

=

co: 40

~

~

~

co:

.....co:

~

30

~

20 10 0

-300 -200 -100 0 100 200 300 400 500 600 Temperature (° F)

CVGraph 6.02 01/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-50 Plant: Watts Bar 2 Materia l: SAS08CL2 Heat: 527828 Orientation: NA Capsule: U Fluence: 6.04E+018 n/cm 1 Capsule U Heat-Affected Zone (HAZ)

Charpy V-Notch Data Temperature (0 F) Input L. E. Computed L. E. Differential

- 11 5 16.0 15.5 0. -5

-11 0 23.0 16.S 6.46

-1 00 7.0 18.9 - l l. 89

-90 23.0 21 I. 2

-80 22.0 24. -2.28

-70 37.0 27.3 9.72

-60 3 1.0 304 0.56

-35 48.0 38.7 9.25

-30 25.0 404 -1 5.43

-20 42.0 43.8 -1.75 IO 56.0 53.0 3.0 1 75 68.0 66.S LS I 1 0 74.0 72.6 1.40 200 7 .0 74.0 -1. 00 220 73.0 74.3 -1.29 CVGraph 6.02 01/09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

      • This record was final approved on 3/26/2020 8:08:22 AM. (This statement was added by the PRIME system upon its validation)

Westinghouse Non-Proprietary Class 3 C-51 Capsule U Heat-Affected Zone (HAZ)

C VG rdph 6.02: Hyperbolic Tange nt Curve Printed on 1/9/2020 12:03 PM A= 50.00 B = 50.00 C = 103.78 TO= -47.73 D = 0.00 Correlation Coeffi cient = 0.976 Equation is A + B * [Ta nh((T-TO)/(C+DT)))

Upper Shelf %Shea r = 100.00 (Fixed) Lower She lf 'YoShear = 0.00 (Fixed)

Temperature at 50% Shear = -47.70 Plant : Watts Ba r 2 Material : SA508CL2 Heat: 527828 Orientation: NA Capsule: U Fluence: 6.04E+o18 n/cm 2 JOO i

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-300 -200 -JOO 0 JOO 200 300 400 500 600 Temperature {° F)

CVGraph 6.02 0 1/09/2020 Page 1/2 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 C-52 Plant: Watts Bar 2 Materia l: SA508CL2 Heat 527828 Orientation: A Capsule: TJ Fluence: 6.04E+0.18 n/cm 2 Capsule U Heat-Affected Zone (HAZ)

Charpy V-Notch Data Temperature{° F) Input %Shear Computed %Shear Differential

-11 5 2 * .o 21.5 3.

  • 2

-11 0 25.0 23.1 1.85

-1 00 20.0 26.8 -6.75

-90 25.0 30.7 -5.69

-80 3 .0 34.9 0.06

-70 55.0 39.4 15.57

-60 45.0 44.1 0.88

-35 60.0 56.1 3.90

-30 45.0 58.5 -1 3.46

-20 60.0 63. 1 -3.05 10 75.0 75.3 -0.26 75 100.0 91.4 8.59 150 100.0 97.8 2. 17 200 100.0 99.2 0.84 220 100.0 99.4 0.57 CVGraph 6.02 01 /09/2020 Page 2/2 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 D-1 APPENDIX D WATTS BAR UNIT 2 SURVEILLANCE PROGRAM CREDIBILITY EVALUATION INTRODUCTION Regulatory Guide 1.99, Revision 2 [Ref. D-1] describes general procedures acceptable to the NRC staff for calculating the effects of neutron radiation embrittlement of the low-alloy steels currently used for light-water-cooled reactor vessels. Position C.2 of Regulatory Guide 1.99, Revision 2, describes the method for calculating the adjusted reference temperature and Charpy upper-shelf energy of reactor vessel beltline materials using surveillance capsule data. The methods of Position C.2 can only be applied when two or more credible surveillance data sets become available from the reactor in question.

Capsule U is the first surveillance capsule to be removed and tested from the Watts Bar Unit 2 reactor vessel.

In accordance with Regulatory Guide 1.99, Revision 2, the credibility of the surveillance data will be judged based on five criteria. However, criterion 3 requires at least two data sets in order to determine the credibility. Since this is the first capsule withdrawn from Watts Bar Unit 2, this criterion cannot be applied to the surveillance forging. For this reason, the credibility of the surveillance forging cannot be determined due to the limited data available. The surveillance weld Heat # was utilized in the surveillance programs of sister-plants; therefore, criterion 3 can be applied to the surveillance weld with consideration of all available sister-plant data.

The purpose of this evaluation is to apply the credibility requirements of Regulatory Guide 1.99, Revision 2, to the Watts Bar Unit 2 reactor vessel surveillance weld data and determine if that surveillance data is credible.

EVALUATION Criterion 1: Materials in the capsules should be those judged most likely to be controlling with regard to radiation embrittlement.

The beltline region of the reactor vessel is defined in Appendix G to 10 CFR Part 50, Fracture Toughness Requirements [Ref. D-2], as follows:

the region of the reactor vessel (shell material including welds, heat affected zones, and plates or forgings) that directly surrounds the effective height of the active core and adjacent regions of the reactor vessel that are predicted to experience sufficient neutron radiation damage to be considered in the selection of the most limiting material with regard to radiation damage.

The Watts Bar Unit 2 reactor vessel consists of the following beltline region materials:

Upper Shell Forging 06, Heat # 411572 Intermediate Shell Forging 05, Heat # 527828 Lower Shell Forging 04, Heat # 528658 Bottom Head Ring 03, Heat # 5329 WCAP-18518-NP March 2020 Revision 0

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Westinghouse Non-Proprietary Class 3 D-2 Upper Shell Forging to Intermediate Shell Forging Circumferential Weld Seam W06 (Weld Wire Heat # 899680 with type Grau L.O. (LW320) flux, lot P23)

Intermediate Shell Forging 05 to Lower Shell Forging 04 Circumferential Weld Seam W05 (Weld Wire Heat # 895075 with type Grau L.O. (LW320) flux, lot P46)

Lower Shell Forging 04 to Bottom Head Ring 03 Circumferential Weld Seam W04 (Weld Wire Heat # 899680 with type Grau L.O. (LW320) flux, lot P23)

The Watts Bar Unit 2 surveillance program utilizes tangential and axial test specimens from the Intermediate Shell Forging 05, Heat # 527828. The surveillance weldment is identical to the closing girth seam weldment between forging 04 and 05. The closing seam used weld wire Heat # 895075 with type Grau L.O. (LW320) flux, lot P46, except for the 1-inch root pass at the I.D. of the vessel. This root pass used weld wire Heat # 899680 with type Grau L.O. (LW320) flux, lot P23, with an as-deposited copper and phosphorous content of 0.03 and 0.009, respectively. However, the surveillance weldment specimens were not removed from this root area.

Per WCAP-9455 [Ref. D-3], the Watts Bar Unit 2 surveillance program was developed to the requirements of ASTM E185-73. At the time of the surveillance program development, the Upper Shell Forging 06 and Bottom Head Ring 03 were not considered a beltline material. Of the other beltline forgings, Intermediate Shell Forging 05 was foreseen to be the most limiting forging. Intermediate Shell Forging 05 has the highest estimated initial and end of life RTNDT and the lowest initial upper-shelf energy value of the Watts Bar Unit 2 beltline forgings. The chemistry values (Cu and Ni weight percent) for the beltline forgings are relatively consistent and no forging is clearly differentiated from the rest by its high copper or nickel content. Therefore, Intermediate Shell Forging 05 was appropriately selected as the base metal material for the surveillance program.

Intermediate Shell Forging 05 to Lower Shell Forging 04 Circumferential Weld Seam W05 was considered the only weld in the beltline region and therefore, was representative of all the beltline welds. Hence, the surveillance program weld was fabricated with the same weld wire heat (# 895075), the same type flux (LW320), and the same flux lot (# P46) as the Intermediate to Lower Shell Forging Circumferential Weld Seam W05.

Therefore, the materials selected for use in the Watts Bar Unit 2 surveillance program were those judged to be most likely limiting with regard to radiation embrittlement according to the accepted methodology at the time the surveillance program was developed.

Based on the discussion above, Criterion 1 is met for the Watts Bar Unit 2 surveillance program.

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Westinghouse Non-Proprietary Class 3 D-3 Criterion 2: Scatter in the plots of Charpy energy versus temperature for the irradiated and unirradiated conditions should be small enough to permit the determination of the 30 ft-lb temperature and upper-shelf energy unambiguously.

Based on engineering judgment, the scatter in the data presented in these plots, as documented in Section 5, is small enough to permit the determination of the 30 ft-lb temperature and the upper-shelf energy of the Watts Bar Unit 2 surveillance materials unambiguously.

Hence, the Watts Bar Unit 2 surveillance program meets Criterion 2.

Criterion 3: When there are two or more sets of surveillance data from one reactor, the scatter of RTNDT values about a best-fit line drawn as described in Regulatory Position 2.1 normally should be less than 28°F for welds and 17°F for base metal. Even if the fluence range is large (two or more orders of magnitude), the scatter should not exceed twice those values. Even if the data fail this criterion for use in shift calculations, they may be credible for determining decrease in upper-shelf energy if the upper shelf can be clearly determined, following the definition given in ASTM E185-82 [Ref. D-4].

This criterion requires at least two data sets in order to determine the credibility. Since this is the first capsule withdrawn from Watts Bar Unit 2, this criterion cannot be applied to the surveillance forging.

However, since the surveillance weld Heat # was utilized in the surveillance programs of sister-plants, this criterion can be applied to the surveillance weld.

The functional form of the least squares method as described in Regulatory Position 2.1 will be utilized to determine a best-fit line for this data and to determine if the scatter of these RTNDT values about this line is less than 28°F for welds and less than 17°F for plates or forgings.

Following is the calculation of the best-fit line as described in Regulatory Position 2.1 of Regulatory Guide 1.99, Revision 2. In addition, the recommended NRC methods for determining credibility will be followed.

The NRC methods were presented to the industry at a meeting held by the NRC on February 12 and 13, 1998 [Ref. D-5]. Of the five cases, Case 4 (Surveillance Data from Plant and Other Sources) most closely represents the situation for the Watts Bar Unit 2 Intermediate to Lower Shell Circumferential Weld Seam W05 (Heat # 895075) weld material. Since only one capsule has been tested, an evaluation of the Watts Bar Unit 2 surveillance data alone cannot be completed.

Evaluation of Weld Data from All Sources (Case 4)

In accordance with the NRC Case 4 guidelines, the data from all sources should be adjusted to the mean chemical composition of all the data. Data applicable to the Watts Bar Unit 2 surveillance weld material is also available from the Catawba Unit 1, Watts Bar Unit 1, and McGuire Unit 2 surveillance programs.

Since data are from multiple sources, the data must be adjusted for chemical and irradiation environment differences. The chemistry adjustment ratios are shown below.

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Westinghouse Non-Proprietary Class 3 D-4 Watts Bar Unit 2 Heat # 895075 surveillance weld metal Cu Wt. % = 0.033, Ni Wt. % = 0.70 (from Table D-1) results in a Regulatory Guide, Position 1.1 Chemistry Factor (CF) = 44.9°F Catawba Unit 1 Heat # 895075 surveillance weld metal Cu Wt. % = 0.05, Ni Wt. % = 0.73 (from Table D-1) results in a Regulatory Guide, Position 1.1 CF = 68°F Watts Bar Unit 1 Heat # 895075 surveillance weld metal Cu Wt. % = 0.03, Ni Wt. % = 0.75 (from Table D-1) results in a Regulatory Guide, Position 1.1 CF = 41°F McGuire Unit 2 Heat # 895075 surveillance weld metal Cu Wt. % = 0.04, Ni Wt. % = 0.74 (from Table D-1) results in a Regulatory Guide, Position 1.1 CF = 54°F Heat # 895075 surveillance data average composition (considering all available capsules)

The average Cu Wt. % = 0.039 and average Ni Wt. % = 0.74 (from Table D-1) results in a Regulatory Guide, Position 1.1 CF = 52.7°F The ratio procedure is then applied considering the average chemical composition. The following ratios are applied to the RTNDT in Table D-1:

RatioWB2 = CFAverage / CFWB2 Surv. Weld = 52.7 / 44.9 = 1.17 RatioCatawba1 = CFAverage / CF Catawba1 Surv. Weld = 52.7 / 68 = 0.78 RatioWB1 = CFAverage / CFWB1 Surv. Weld = 52.7 / 41 = 1.29 RatioMcGuire2 = CFAverage / CF McGuire2 Surv. Weld = 52.7 / 54 = 0.98 Table D-1 calculates the adjusted RTNDT for weld Heat # 895075 in order to calculate the interim CF for the credibility evaluation.

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Westinghouse Non-Proprietary Class 3 D-5 Table D-1 Mean Chemical Composition and Temperature for Weld Heat # 895075 Inlet Temp. Measured Adjusted Cu(a) Ni(a) Chemistry Material Capsule Temp.(b) Adjust.(c) RTNDT(d) RTNDT(e)

(Wt. %) (Wt. %) Ratio

(°F) (°F) (°F) (°F)

Watts Bar Unit 2 Surveillance Weld U 0.033 0.70 1.17 559 -0.4 32.6 37.67 (Heat # 895075)

Z 0.05 0.73 0.78 562 2.6 1.91 3.52 Catawba Unit 1 Surveillance Weld Y 0.05 0.73 0.78 562 2.6 17.79 15.90 (Heat # 895075)

V 0.05 0.73 0.78 562 2.6 26.5 22.70 U 0.03 0.75 1.29 560 0.6 0.0 0.77 Watts Bar Unit 1 W 0.03 0.75 1.29 560 0.6 30.5 40.12 Surveillance Weld (Heat # 895075) X 0.03 0.75 1.29 560 0.6 25.8 34.06 Z 0.03 0.75 1.29 560 0.6 13.9 18.71 V 0.04 0.74 0.98 557 -2.4 38.51 35.39 McGuire Unit 2 X 0.04 0.74 0.98 557 -2.4 35.93 32.86 Surveillance Weld (Heat # 895075) U 0.04 0.74 0.98 557 -2.4 23.81 20.98 W 0.04 0.74 0.98 557 -2.4 43.76 40.53 MEAN --- 0.039 0.74 - 559.4 - -

Notes:

(a) Watts Bar Unit 2 data is the average of the values in Table 4-1. Catawba Unit 1, Watts Bar Unit 1, and McGuire Unit 2 data is taken from WCAP-18191-NP [Ref. D-6].

(b) Watts Bar Unit 2 temperature is determined by averaging (time-weighted) the inlet temperatures for all cycles prior to the capsule being removed. Watts Bar Unit 1 and McGuire Unit 2 data is taken from WCAP-18191-NP.

Catawba Unit 1 data is taken from WCAP-17669-NP [Ref. D-7].

(c) Temperature Adjustment = Tcapsule - Taverage.

(d) Watts Bar Unit 2 data is taken from Section 5. Catawba Unit 1, Watts Bar Unit 1, and McGuire Unit 2 data is taken from WCAP-18191-NP.

(e) Adjusted RTNDT = (RTNDT, Measured + Temp. Adjustment) x (Chemistry Ratio).

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Westinghouse Non-Proprietary Class 3 D-6 Table D-2 calculates the interim CF for weld Heat # 895075 considering all available data adjusted to account for chemical and irradiation environment differences.

Table D-2 Heat # 895075 Interim Chemistry Factor Using All Available Surveillance Data Capsule Fluence(a) Adjusted FF*RTNDT Material Capsule (x 1019 n/cm2, FF(b) RTNDT(a) FF2

(°F)

E > 1.0 MeV) (°F)

Watts Bar Unit 2 Surveillance Weld U 0.604 0.859 37.67 32.35 0.738 (Heat # 895075)

Z 0.286 0.658 3.52 2.31 0.433 Catawba Unit 1 Surveillance Weld Y 1.290 1.071 15.90 17.03 1.147 (Heat # 895075)

V 2.270 1.222 22.70 27.73 1.493 U 0.447 0.776 0.77 0.60 0.602 Watts Bar Unit 1 W 1.080 1.022 40.12 40.98 1.044 Surveillance Weld (Heat # 895075) X 1.710 1.148 34.06 39.08 1.317 Z 2.40 1.236 18.71 23.12 1.528 V 0.302 0.672 35.39 23.78 0.452 McGuire Unit 2 X 1.380 1.089 32.86 35.80 1.187 Surveillance Weld (Heat # 895075) U 1.900 1.176 20.98 24.67 1.382 W 2.82 1.276 40.53 51.71 1.628 SUM: 319.18 12.949 2

CF Surv. Weld = (FF

  • RTNDT) ÷ (FF ) = (319.18) ÷ (12.949) = 24.6°F Notes:

(a) Fluence taken from Section 6.0 for Watts Bar Unit 2 and WCAP-18191-NP [Ref. D-6] for Catawba Unit 1, Watts Bar Unit 1, and McGuire Unit 2. Adjusted RTNDT taken from Table D-1.

(b) FF = fluence factor = f(0.28 - 0.10*log (f)).

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Westinghouse Non-Proprietary Class 3 D-7 The scatter of RTNDT values about the functional form of a best-fit line drawn as described in Regulatory Position 2.1 is presented in Table D-3.

Table D-3 Heat # 895075 Surveillance Capsule Data Scatter about the Best-Fit Line Using All Available Surveillance Data CF(a) Capsule Adjusted Predicted Scatter

<28°F Material Capsule (Slopebest-fit) Fluence(b) FF(c) RTNDT(d) RTNDT(e) RTNDT(f)

(Weld)

(°F) (x 1019 n/cm2) (°F) (°F) (°F)

Watts Bar Unit 2 Surveillance Weld U 24.6 0.604 0.859 37.7 21.1 16.5 Yes (Heat # 895075)

Z 24.6 0.286 0.658 3.5 16.2 12.7 Yes Catawba Unit 1 Surveillance Weld Y 24.6 1.29 1.071 15.9 26.3 10.4 Yes (Heat # 895075)

V 24.6 2.27 1.222 22.7 30.1 7.4 Yes U 24.6 0.447 0.776 0.8 19.1 18.3 Yes Watts Bar Unit 1 W 24.6 1.08 1.022 40.1 25.1 15.0 Yes Surveillance Weld (Heat # 895075) X 24.6 1.71 1.148 34.1 28.2 5.8 Yes Z 24.6 2.40 1.236 18.7 30.4 11.7 Yes V 24.6 0.302 0.672 35.4 16.5 18.9 Yes McGuire Unit 2 X 24.6 1.38 1.089 32.9 26.8 6.1 Yes Surveillance Weld (Heat # 895075) U 24.6 1.90 1.176 21.0 28.9 7.9 Yes W 24.6 2.82 1.276 40.5 31.4 9.1 Yes Notes:

(a) CF calculated in Table D-2.

(b) Fluence taken from Section 6 for Watts Bar Unit 2 and WCAP-18191-NP [Ref. D-6] for Catawba Unit 1, Watts Bar Unit 1, and McGuire Unit 2.

(c) FF = fluence factor = f(0.28 - 0.10*log (f)).

(d) Adjusted RTNDT taken from Table D-1.

(e) Predicted RTNDT = CF x FF.

(f) Scatter RTNDT = Absolute Value [Predicted RTNDT - Adjusted RTNDT].

Table D-3 indicates that 12 of the 12 surveillance data points fall inside the +/- 1 of 28F scatter band for surveillance weld materials. 100% of the data are bounded; therefore, the surveillance weld data is deemed credible per the third criterion.

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Westinghouse Non-Proprietary Class 3 D-8 Criterion 4: The irradiation temperature of the Charpy specimens in the capsule should match the vessel wall temperature at the cladding/base metal interface within +/- 25°F.

The capsule specimens are located in the reactor between the neutron shield pads and the vessel wall and are positioned opposite the center of the core. The test capsules are located in guide tubes attached to the neutron shielding pads. The location of the specimens with respect to the reactor vessel beltline provides assurance that the reactor vessel wall and the specimens experience equivalent operating conditions such that the temperatures will not differ by more than 25°F. Hence, this criterion is met.

Hence, Criterion 4 is met for the Watts Bar Unit 2 surveillance program.

Criterion 5: The surveillance data for the correlation monitor material in the capsule should fall within the scatter band of the database for that material.

Correlation Monitor Materials (CMM) were included in some plants reactor vessel surveillance programs in order to provide data to improve the predictive model and confirm Revision 2 of Regulatory Guide 1.99.

See NUREG/CR-6413, ORNL/TM-13133 [Ref. D-8]. However, the Watts Bar Unit 2 surveillance program does not contain correlation monitor material. Hence, this criterion is not applicable to the Watts Bar Unit 2 surveillance program.

CONCLUSION Based on the preceding responses to the 5 criteria of Regulatory Guide 1.99, Revision 2, Section B, the Watts Bar Unit 2 surveillance weld data for Heat # 895075 are deemed credible. Since only one capsule has been withdrawn and tested containing the Watts Bar Unit 2 surveillance forging material, insufficient data exists to determine the credibility of the surveillance forging material.

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Westinghouse Non-Proprietary Class 3 D-9 REFERENCES D-1 U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, Regulatory Guide 1.99, Revision 2, Radiation Embrittlement of Reactor Vessel Materials, May 1988.

[ADAMS Accession Number ML003740284]

D-2 Code of Federal Regulations 10 CFR 50, Appendix G, Fracture Toughness Requirements, U.S.

Nuclear Regulatory Commission, Federal Register, November 29, 2019.

D-3 Westinghouse Report WCAP-9455, Revision 4, Tennessee Valley Authority Watts Bar Unit No. 2 Reactor Vessel Radiation Surveillance Program, August 2019.

D-4 ASTM E185-82, Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels, American Society for Testing and Materials, 1982.

D-5 K. Wichman, M. Mitchell, and A. Hiser, USNRC, Generic Letter 92-01 and RPV Integrity Workshop Handouts, NRC/Industry Workshop on RPV Integrity Issues, February 12, 1998.

[ADAMS Accession Number ML110070570].

D-6 Westinghouse Report WCAP-18191-NP, Revision 1, Watts Bar Unit 2 Heatup and Cooldown Limit Curves for Normal Operation and Supplemental Reactor Vessel Integrity Evaluations, February 2020.

D-7 Westinghouse Report WCAP-17669-NP, Revision 1, Catawba Unit 1 Measurement Uncertainty Recapture (MUR) Power Uprate: Reactor Vessel Integrity and Neutron Fluence Evaluations, October 2015.

D-8 NUREG/CR-6413, ORNL/TM-13133, Analysis of the Irradiation Data for A302B and A533B Correlation Monitor Materials, April 1996.

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WCAP-18518-NP Revision 0 Proprietary Class 3

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Approval Information Author Approval Lynch Donald Mar-25-2020 11:15:21 Author Approval Fischer Greg A Mar-25-2020 14:06:09 Reviewer Approval Hall J Brian Mar-25-2020 14:21:13 Reviewer Approval Amiri Benjamin W Mar-25-2020 14:36:14 Approver Approval Patterson Lynn Mar-25-2020 14:43:00 Approver Approval Houssay Laurent Mar-25-2020 16:07:07 Hold to Release Approval Lynch Donald Mar-26-2020 08:08:22 Files approved on Mar-26-2020

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