ML25091A300
| ML25091A300 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 04/01/2025 |
| From: | Duke Energy Progress |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML25091A290 | List: |
| References | |
| RA-25-0067 WCAP-18900-NP, Rev 0 | |
| Download: ML25091A300 (1) | |
Text
ENCLOSURE 4 ATTACHMENT 4 H.B. ROBINSON STEAM ELECTRIC PLANT, UNIT NUMBER 2 Westinghouse WCAP-18900-NP, Revision 0, Flaw Tolerance Evaluation for Susceptible Reactor Coolant Loop Cast Austenitic Stainless Steel Piping Components for H.B. Robinson Unit 2, November 2024
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 WCAP-18900-NP November 2024 Revision 0 Flaw Tolerance Evaluation for Susceptible Reactor Coolant Loop Cast Austenitic Stainless Steel Piping Components for H.B. Robinson Unit 2
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3
- Electronically approved records are authenticated in the electronic document management system.
Westinghouse Electric Company LLC 1000 Westinghouse Drive Cranberry Township, PA 16066, USA
© 2024 Westinghouse Electric Company LLC All Rights Reserved WCAP-18900-NP Revision 0 Flaw Tolerance Evaluation for Susceptible Reactor Coolant Loop Cast Austenitic Stainless Steel Piping Components for H.B. Robinson Unit 2 Joshua A. Coleman*
Reactor Vessel/Containment Vessel Design and Analysis November 2024 Verifier:
Maria A. Rizzilli*
Reactor Vessel/Containment Vessel Design and Analysis Reviewer:
Anees Udyawar*
Reactor Vessel/Containment Vessel Design and Analysis Manager:
Remington W. Iddings*
Reactor Vessel/Containment Vessel Design and Analysis
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 iii WCAP-18900-NP November 2024 Revision 0 FOREWORD This report contains Westinghouse Electric Company LLC proprietary information and data which has been identified by brackets. Coding (a,c,e) associated with the brackets sets forth the basis on which the information is considered proprietary.
The proprietary information and data contained in this report were obtained at considerable Westinghouse expense and its release could seriously affect our competitive position. Westinghouse has policies in place to identify proprietary information. Under that system, information is held in confidence if it falls in one or more of several types, the release of which might result in the loss of an existing or potential competitive advantage, as follows:
(a)
The information reveals the distinguishing aspects of a process (or component, structure, tool, method, etc.) where prevention of its use by any of Westinghouse's competitors without license from Westinghouse constitutes a competitive economic advantage over other companies.
(c)
Its use by a competitor would reduce their expenditure of resources or improve their competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing a similar product.
(e)
It reveals aspects of past, present, or future Westinghouse or customer funded development plans and programs of potential commercial value to Westinghouse.
The document herein is bracketed and marked to indicate the bases for withholding. The justification for withholding is indicated in both proprietary and non-proprietary versions by means of lower-case letters (a)
(c) and (e) located as a superscript immediately following the brackets enclosing each item of information being identified as proprietary or in the margin opposite such information. These lower-case letters refer to the types of information Westinghouse customarily holds in confidence identified above. The proprietary information in the brackets is provided in the proprietary version of this report (WCAP-18900-P).
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 iv WCAP-18900-NP November 2024 Revision 0 RECORD OF REVISIONS Revision Date Revision Description 0
November 2024 Original Issue.
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 v
WCAP-18900-NP November 2024 Revision 0 TABLE OF CONTENTS LIST OF TABLES....................................................................................................................................... vi LIST OF FIGURES.................................................................................................................................... vii EXECUTIVE
SUMMARY
........................................................................................................................ viii 1
INTRODUCTION........................................................................................................................ 1-1 2
LOADINGS, STRESSES AND GEOMETRY............................................................................. 2-1 3
MATERIAL PROPERTIES.......................................................................................................... 3-1 3.1 SCREENING CRITERIA................................................................................................ 3-1 3.2 THERMAL AGING SUSCEPTIBILITY........................................................................ 3-2 4
ACCEPTANCE CRITERIA......................................................................................................... 4-1 5
FATIGUE CRACK GROWTH..................................................................................................... 5-1 6
FLAW TOLERANCE EVALUATION......................................................................................... 6-1 7
SUMMARY
AND DISCUSSION................................................................................................ 7-1 8
REFERENCES............................................................................................................................. 8-1
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 vi WCAP-18900-NP November 2024 Revision 0 LIST OF TABLES Table 2-1: Dimensions, Operating Temperatures, and Pressure of RCL CASS Components for H.B.
Robinson Unit 2............................................................................................................... 2-3 Table 2-2: H.B. Robinson Unit 2 Bounding Pipe Loads............................................................................ 2-4 Table 2-3: H.B. Robinson Unit 2 Design Transient Cycles for 80 Years................................................... 2-5 Table 3-1: CASS Thermal Aging Susceptibility Screening Criteria.......................................................... 3-3 Table 3-2: Screening Criteria for Thermal Aging of CASS Materials from NUREG-2191 Rev. 1........... 3-3 Table 3-3: H.B. Robinson Unit 2 Primary Loop Piping Static Cast Elbow (A-351 CF8M) CMTR Chemistry, Delta Ferrite, and Thermal Aging Susceptibility Screening.......................... 3-4 Table 6-1: Acceptable Initial Flaw Sizes (% Through-Wall Thickness) for Susceptible CASS Elbow Components..................................................................................................................... 6-3
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 vii WCAP-18900-NP November 2024 Revision 0 LIST OF FIGURES Figure 2-1: Schematic Diagram for H.B. Robinson Unit 2 Primary Loop................................................ 2-2 Figure 2-2: Axial and Circumferential Residual Stress Distributions for Austenitic Stainless Steel Pipe Welds............................................................................................................................... 2-6 Figure 6-1: Axial Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Hot Leg........ 6-4 Figure 6-2: Circumferential Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Hot Leg................................................................................................................................... 6-5 Figure 6-3: Axial Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Crossover Leg................................................................................................................................... 6-6 Figure 6-4: Circumferential Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Crossover Leg.................................................................................................................. 6-7 Figure 6-5: Axial Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Cold Leg...... 6-8 Figure 6-6: Circumferential Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Cold Leg................................................................................................................................... 6-9
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 viii WCAP-18900-NP November 2024 Revision 0 EXECUTIVE
SUMMARY
The primary reactor coolant loop (RCL) at H.B. Robinson Unit 2 is constructed from static cast elbows made of ASTM A-351 Grade CF8M material, while the straight pipe components are made of A-376 TP316 (Reference 6). The cast austenitic stainless steel (CASS) A-351 CF8M material may be susceptible to thermal aging at the reactor operating temperature. Thermal aging of CASS material results in embrittlement, that is, a decrease in the ductility, impact strength, and fracture toughness and an increase in hardness and tensile strength of the material. As stated in the Grimess Letter (Reference 1) and incorporated in NUREG-2191, Volume 2, aging management program (AMP) XI.M12 (Reference 2, including the draft GALL-SLR report for comment [Reference 9]), since portions of the base metal in the reactor coolant loop piping may not receive periodic inspection in accordance with Section XI of the ASME Code (Reference 3),
thermal embrittlement susceptibility of piping components constructed from CASS material should be assessed for each heat of material. Susceptibility of RCL CASS components in H.B. Robinson Unit 2 can be determined using the screening criteria given in NUREG-2191 based on the molybdenum content, casting method, ferrite content, and fracture toughness. If a particular heat is found to be not susceptible, no additional inspections or evaluations are required to demonstrate that the material has adequate toughness. Otherwise, aging management can be accomplished through volumetric examination or plant-specific flaw tolerance evaluations using plant specific geometry and stress information.
In determining susceptibility of the CASS components to thermal aging, the delta ferrite content for H.B. Robinson Unit 2 is primarily estimated using Hulls Equivalent Factor from NUREG/CR-4513 Revision 1 (Reference 4) and Revision 2 (Reference 5) according to the Grimess Letter and NUREG-2191.
It was determined that the straight piping components (A-376 TP316) are not susceptible to thermal aging while all the statically cast elbow pipe components (A-351 CF8M) are susceptible as described in Section 3.2 of this report.
In this report, a flaw tolerance evaluation of the susceptible CASS static cast elbow pipe components in H.B. Robinson Unit 2 is performed in accordance with IWB-3640 and Appendix C of ASME Section XI based on guidelines from NUREG-2191 and the Grimess Letter. Based on the flaw tolerance analysis results, the susceptible CASS elbow pipe components are flaw tolerant for 80 years of service.
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 1-1 WCAP-18900-NP November 2024 Revision 0 1
INTRODUCTION The primary reactor coolant loop (RCL) at H.B. Robinson Unit 2 is constructed from static cast elbows made of ASTM A-351 Grade CF8M material, while the straight pipe components are made of A-376 TP316 (Reference 6). The CASS A-351 CF8M material may be susceptible to thermal aging at the reactor operating temperature (see Section 3). Thermal aging of CASS material results in embrittlement, that is, a decrease in the ductility, impact strength, and fracture toughness and an increase in hardness and tensile strength of the material. Depending on the material composition, the Charpy impact energy of a component made of CASS material could decrease to a smaller fraction of its original value after prolonged exposure to reactor coolant temperatures during service.
As stated in NUREG-2191 aging management program (AMP) XI.M12 (Reference 2) and in the Grimess Letter (Reference 1), since portions of the base metal in the reactor coolant loop piping may not receive periodic inspection in accordance with Section XI of the ASME Code (Reference 3), the susceptibility of piping constructed from CASS material should be assessed for each heat of material. Susceptibility of RCL CASS piping components in H.B. Robinson Unit 2 can be determined using the screening criteria given in the Grimess Letter and NUREG-2191 based on the molybdenum content, casting method, and ferrite content. If a particular heat is found to be not susceptible, no additional inspections or evaluations are required to demonstrate that the material has adequate toughness. Otherwise, aging management can be accomplished through volumetric examination or plant-specific flaw tolerance evaluations using plant-specific geometry, materials, transient definitions and stress information. This report provides a plant-specific flaw tolerance evaluation for the H.B. Robinson Unit 2 RCL to demonstrate that the piping components have adequate fracture toughness and are flaw tolerant for up to 80 years of service life.
The susceptibility of CASS piping components to thermal aging is determined according to molybdenum content, casting methods, and delta ferrite content per NUREG-2191 and the Grimess Letter. According to NUREG-2191 and the Grimess Letter, material heats with high molybdenum content (A-351, Grades CF3M, CF3MA, and CF8M or other steels with approximately 2%-3% molybdenum content) for statically cast elbow components which have delta ferrite content greater than 14% are potentially susceptible to thermal aging. Also considered in this report is the screening criteria in NUREG-2191, Volume 2, Revision 1 (Reference 9). NUREG-2191, Revision 1 is currently a draft report, but contains more limiting thermal aging embrittlement screening criteria based on the latest information in NUREG/CR-4513 Rev. 2 (Reference 5).
In determining susceptibility of the CASS piping components to thermal aging, the delta ferrite content for H.B. Robinson Unit 2 is estimated using Hulls Equivalent Factor in NUREG/CR-4513 Revision 1 (Reference 4) according to the Grimess Letter and NUREG-2191. The Hulls Equivalent Factor correlations in Revision 1 of NUREG/CR-4513 are the same as Revision 2 of NUREG/CR-4513 (Reference 5).
A flaw tolerance evaluation of the susceptible CASS piping components in H.B. Robinson Unit 2 can be performed in accordance with IWB-3640 and Appendix C of ASME Section XI based on recommendations from the Grimess Letter and NUREG-2191 (References 2 and 9). The in-service inspection code of record for H.B. Robinson Unit 2 is the 2017 Edition of ASME Section XI. For the flaw tolerance evaluation herein, the 2019 Edition of ASME Section XI is used (Reference 8), see Section 4 for further discussion. The
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 1-2 WCAP-18900-NP November 2024 Revision 0 objective of the flaw tolerance evaluation is to demonstrate that even with thermal aging, the susceptible CASS piping components are flaw tolerant for up to 80 years of service.
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 2-1 WCAP-18900-NP November 2024 Revision 0 2
LOADINGS, STRESSES AND GEOMETRY In order to perform the flaw tolerance evaluation for H.B. Robinson Unit 2 RCL CASS piping components, the first step is the determination of the maximum allowable end-of-evaluation period flaw sizes. The maximum allowable end-of-evaluation period flaw size is the size to which an indication is allowed to grow to until the next inspection or evaluation period. This particular flaw size is determined based on the piping loads, geometry and the material properties of the component. The evaluation guidelines and procedures for calculating the maximum allowable end-of-evaluation period flaw sizes are described in paragraph IWB-3640 and Appendix C of the ASME Section XI Code (Reference 3). The maximum allowable end-of-evaluation period flaw sizes are established based on the limiting loadings for the components of interest from the normal, upset, test, emergency, and faulted conditions, as applicable.
H.B. Robinson Unit 2 reactor coolant loop typical piping layouts for the hot leg, crossover leg, and cold leg components are shown in Figure 2-1. As discussed in Section 3.2, it is determined that all the H.B. Robinson Unit 2 reactor coolant loop elbow heats are potentially susceptible to thermal aging since all elbows are A-351 CF8M static cast and have calculated delta ferrite values greater than 14%. The susceptible hot leg, crossover leg, and cold leg elbow geometry along with the normal operating temperature and pressure parameters are provided in Table 2-1 for H.B. Robinson Unit 2. The piping loads considered in the flaw tolerance evaluation consist of loads due to pressure, deadweight, thermal expansion, and seismic (operational basis earthquake and design basis earthquake).
Design pressure and thermal transients are used in the fatigue crack growth (FCG) analysis for the susceptible CASS elbows reactor coolant loop. [
] a,c,e The bounding design transients and the number of occurrences for 80 years are shown in Table 2-3. Note that these cycles bound the 80-year projected cycles for H.B. Robinson Unit 2. All of the transients and cycles in Table 3.9.1-1 of the FSAR (Reference 13) are considered in Table 2-3.
Residual stresses due to the weld fabrication process are also considered in the fatigue crack growth analysis. The residual stress values were obtained from the technical basis document for austenitic steel piping flaw evaluation (Reference 7), and are used in the evaluation herein for the heat affected zones of the susceptible CASS piping components. The through-wall axial and circumferential residual stress profiles used in the fatigue crack growth analysis are shown in Figure 2-2.
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 2-2 WCAP-18900-NP November 2024 Revision 0 a,c,e Figure 2-1: Schematic Diagram for H.B. Robinson Unit 2 Primary Loop (Reference 6)
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 2-3 WCAP-18900-NP November 2024 Revision 0 Table 2-1: Dimensions, Operating Temperatures, and Pressure of RCL CASS Components for H.B.
Robinson Unit 2 a,c,e
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 2-4 WCAP-18900-NP November 2024 Revision 0 a,c,e Table 2-2: H.B. Robinson Unit 2 Bounding Pipe Loads
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Westinghouse Non-Proprietary Class 3 2-5 WCAP-18900-NP November 2024 Revision 0 a,c,e Table 2-3: H.B. Robinson Unit 2 Design Transient Cycles for 80 Years
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 2-6 WCAP-18900-NP November 2024 Revision 0 Figure 2-2: Axial and Circumferential Residual Stress Distributions for Austenitic Stainless Steel Pipe Welds (Reference 7)
Notes:
- 1. S = 30 ksi
- 2. Considerable variation with weld heat input
- 3. = i [1.0 - 6.91(a/t) + 8.69(a/t)2 - 0.48(a/t)3 - 2.03(a/t)4]
i = stress at inner surface (a = 0) a = distance through pipe weld thickness t = pipe weld thickness
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 3-1 WCAP-18900-NP November 2024 Revision 0 3
MATERIAL PROPERTIES The pre-service fracture toughness of cast austenitic stainless steel has been found to be very high at operating temperatures. However, cast austenitic stainless steel is susceptible to thermal aging after prolonged exposure to the reactor coolant operating temperature. Thermal aging of CASS material results in embrittlement, that is, a decrease in the ductility, impact strength, and fracture toughness and an increase in hardness and tensile strength of the material. Depending on the material composition, the Charpy impact energy of a cast austenitic stainless steel component could decrease to a smaller fraction of its original value after prolonged exposure to the reactor coolant operating temperatures during service. The primary reactor coolant loop (RCL) statically cast elbow components in H.B. Robinson Unit 2 are constructed from cast austenitic stainless steel (CASS) A-351 Grade CF8M material, and the wrought pipe components are constructed from A-376 TP316.
3.1 SCREENING CRITERIA According to the NUREG-2191, AMP XI.M12 (Reference 2), aging management is accomplished through a component-specific flaw tolerance evaluation of susceptible CASS materials in accordance with the ASME Code,Section XI. Susceptibility of RCL CASS piping components in H.B. Robinson Unit 2 can be determined using the screening criteria given in the Grimess Letter (Reference 1) and NUREG-2191 AMP XI.M12 based on the molybdenum content, casting method, and ferrite content.
According to the Grimess Letter and NUREG-2191, material heats with high molybdenum content (steels with approximately 2%-3% molybdenum content) for statically cast elbow components which have delta ferrite content greater than 14% are potentially susceptible to thermal aging. Piping components with low molybdenum are not susceptible for any amount of delta ferrite content. The screening criteria used for all the RCL CASS components is shown in Table 3-1. This screening criteria will be used for H.B. Robinson Unit 2 to determine susceptibility of the RCL elbow components fabricated from A-351 CF8M material.
Also considered in this report is the screening criteria in NUREG-2191, Volume 2, Revision 1 (Reference 9). NUREG-2191, Revision 1 is currently a draft report, but contains more limiting thermal aging embrittlement screening criteria based on the latest information in NUREG/CR-4513 Rev. 2 (Reference 5). Table 3-2 provides the screening criteria per NUREG-2191, Volume 2, Revision 1. However, the updates in Reference 9 do not impact this analysis since all the H.B. Robinson Unit 2 CASS RCL elbows are potentially susceptible to thermal aging.
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 3-2 WCAP-18900-NP November 2024 Revision 0 3.2 THERMAL AGING SUSCEPTIBILITY Based on the guidance in the Grimess Letter and NUREG-2191, the delta ferrite content is estimated using Hulls Equivalent Factor in NUREG/CR-4513 Revision 1 (Reference 4) to determine the elbow components susceptibility to thermal aging. Note that the Hulls Equivalent Factor correlations in Revision 1 of NUREG/CR-4513 (Reference 4) are the same as Revision 2 of NUREG/CR-4513 (Reference 5). Both NUREG/CR-4513, Revision 1 and NUREG/CR-4513, Revision 2 are staff-approved methods for calculating delta ferrite in CASS materials. H.B. Robinson Unit 2 plant-specific Certified Material Test Report (CMTR) chemistry values for all the statically cast elbow heats are provided in Table 3-3, along with the delta ferrite calculations per NUREG/CR-4513, Revision 1. Based on H.B. Robinson Unit 2 plant-specific CMTR chemistry values, it is determined that all reactor coolant loop (RCL) elbow heat numbers at H.B. Robinson Unit 2 are potentially susceptible to thermal aging as shown in Table 3-3.
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 3-3 WCAP-18900-NP November 2024 Revision 0 Table 3-1: CASS Thermal Aging Susceptibility Screening Criteria (Reference 1)
Mo Content (Wt. %)
Casting Method Ferrite Content Significance of Thermal Aging High (2.0-3.0)
Static 14%
Not Susceptible
> 14%
Potentially Susceptible Centrifugal 20%
Not Susceptible
> 20%
Potentially Susceptible Low (0.50 max)
Static 20%
Not Susceptible
> 20%
Potentially Susceptible Centrifugal All Not Susceptible Table 3-2: Screening Criteria for Thermal Aging of CASS Materials from NUREG-2191 Rev. 1 (Reference 9)
Mo Content (Wt. %)
Casting Method Ferrite Content Significance of Thermal Aging High (2.0-3.0) with < 10 wt.% Ni (10 wt.% Ni)
Static 14%
( 11%)
Non-Significant High (2.0-3.0) with < 10 wt.% Ni (10 wt.% Ni)
> 14%
(>11%)
Potentially Significant High (2.0-3.0) with < 10 wt.% Ni (10 wt.% Ni)
Centrifugal 19%
( 13%)
Non-significant High (2.0-3.0) with < 10 wt.% Ni (10 wt.% Ni)
> 19%
(> 13%)
Potentially Significant Low (0.5 max)
Static 20%
Non-Significant
> 20%
Potentially Significant Centrifugal All Non-Significant
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 3-4 WCAP-18900-NP November 2024 Revision 0 Table 3-3: H.B. Robinson Unit 2 Primary Loop Piping Static Cast Elbow (A-351 CF8M) CMTR Chemistry, Delta Ferrite, and Thermal Aging Susceptibility Screening a,c,e
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Westinghouse Non-Proprietary Class 3 4-1 WCAP-18900-NP November 2024 Revision 0 4
ACCEPTANCE CRITERIA Per NUREG-2191, Volume 2, AMP XI.M12, the CASS components are to be evaluated in accordance with the applicable procedures in ASME Code,Section XI. The acceptance criteria for the determination of allowable flaw sizes in high toughness base materials are contained in paragraph IWB-3640 in the ASME Section XI Code. Although rapid, nonductile failure is possible for ferritic material at low temperatures, it is not applicable to high toughness material such as austenitic stainless steel. In high toughness materials, the higher ductility leads to two possible modes of failure: plastic collapse or unstable ductile tearing. The second mechanism can occur when the applied J integral exceeds the JIc fracture toughness, and some stable tearing occurs prior to failure. If this mode of failure is dominant, the load carrying capacity is less than that predicted by the plastic collapse mechanism. The allowable flaw sizes of paragraph IWB-3640 in the ASME Section XI Code for the high toughness base materials were determined based on the assumption that plastic collapse would be achieved and would be the dominant mode of failure. However, due to the reduced toughness of the submerged arc and shielded metal arc welds, it is possible that crack extension and unstable ductile tearing could occur and be the dominant mode of failure. To account for this effect, penalty factors called Z factors were developed in ASME Section XI Code Appendix C, which are to be multiplied by the loadings at these welds. Thus, the effects of unstable ductile tearing due to reduced toughness of thermally aged cast austenitic stainless steel can therefore be addressed through the use of Z factors for submerged arc welds in accordance with the IWB-3640 flaw evaluation procedure and acceptance criteria. The yield and ultimate stress values used in the maximum allowable end-of-evaluation are based on H. B. Robinson CMTRs as provided in [
] a,c,e The axial allowable flaw sizes are determined based on pressure hoop stresses per the guidance of Appendix C of ASME Section XI. The determination of circumferential allowable flaw sizes is based on all the loads from Table 2-2, such as pressure, deadweight, thermal expansion, and seismic (i.e. OBE or SSE). For the various service conditions, the load combinations are as follows:
Normal Condition (Level A): Pressure + Deadweight + Thermal Expansion Upset Condition (Level B including test): Pressure + Deadweight + Thermal Expansion + OBE Emergency/Faulted (Level C and D): Pressure + Deadweight + Thermal Expansion + SSE According to the Grimess Letter (Reference 1), the results from the Argonne National Laboratory Research Program also indicate that the lower bound fracture toughness of thermally aged cast austenitic stainless steel is similar to that of submerged arc welds (SAW). In accordance with the flaw evaluation guidelines in Grimess Letter if the delta ferrite content for the cast austenitic stainless steel does not exceed 25%, the flaw evaluation can be performed in accordance with the evaluation procedures in paragraph IWB-3640 for submerged arc welds disregarding the ASME code restrictions of 20% ferrite in Appendix C of Section XI (i.e., 2017 Edition). As previously discussed, the susceptibility of CASS elbow components to thermal aging is determined by estimating the delta ferrite content per Hulls Equivalent Factor in NUREG/CR-4513, Revision 1 (Reference 4) per NUREG-2191, Chapter XI.M12. Since all but one of the delta ferrite contents for the susceptible RCL CASS piping components for H.B. Robinson Unit 2 were shown to be less than 25% per Table 3-3, a flaw tolerance evaluation can therefore be performed using the evaluation procedures and acceptance criteria for indications in SAW contained in paragraph IWB-3640 of ASME Section XI. Per Table 3-3, the H.B. Robinson Unit 2 crossover leg [
] a,c,e using Hulls Equivalent Factor methodology. For
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 4-2 WCAP-18900-NP November 2024 Revision 0 this particular heat [
] a,c,e, the draft GALL-SLR report (Reference 9) allows the use of the 2019 Edition of Section XI (Reference 8) for use in flaw evaluation acceptance criteria.
The 2019 Edition of ASME Section XI (Reference 8), which has been approved by the U.S. NRC in 10 CFR 50.55a, updates Appendix C to include flaw evaluation methodology for materials with delta ferrite greater than 14%.
The in-service inspection (ISI) code of record for H.B. Robinson Unit 2 is the 2017 Edition of ASME Section XI (Reference 3). The evaluation method for the case with the delta ferrite content 20% is not provided in Appendix C of the 2017 Edition of ASME Section XI (Reference 3). However, the Grimess Letter (Reference 1) states that the flaw evaluation can be performed in accordance with the evaluation procedures in paragraph IWB-3640 for SAW, disregarding the ASME code restrictions of 20% ferrite in Appendix C of Section XI. In addition, Appendix C of the 2019 Edition of the ASME Code Section XI (Reference 8) removed the limitation of delta ferrite 20% and provides flaw evaluation of procedures for CASS with delta ferrite content > 14% to be evaluated per elastic plastic fracture mechanics (EPFM) criteria. The 2019 Edition of Section XI also expands the applicability of the SAW Z factor load multiplier to be applicable for CF8 or equivalent chemical composition product with ferrite content greater than 14%
(i.e., CF8M materials). Note that the 2019 Edition of ASME Section XI has been approved by the U.S. NRC in 10 CFR 50.55a. Therefore, the flaw evaluation for the heats with delta ferrite content 20% would be in accordance with the procedures specified in the 2019 Edition of the ASME Section XI Appendix C. Thus, the evaluation procedures and acceptance criteria contained in paragraph IWB-3640 of ASME Section XI are used in the generation of the flaw tolerance charts for susceptible H.B. Robinson Unit 2 reactor coolant loop elbows made of CASS material.
The U.S. NRC has published GALL-SLR NUREG-2191, Volume 2 AMP XI.M12 (Reference 2) for subsequent license renewal (SLR) for 80 years. Per NUREG-2191 Revision 1 (Reference 9), the U.S. NRC is in the process of changing the GALL-SLR AMP XI.M12 to add the 2019 Edition of ASME Code,Section XI, Non-Mandatory Appendix C. Thus, the flaw tolerance evaluation procedures and acceptance criteria contained in paragraph IWB-3640 of the 2019 Edition of ASME Section XI are used herein for up to 80 years of operation at H.B. Robinson Unit 2.
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 5-1 WCAP-18900-NP November 2024 Revision 0 5
FATIGUE CRACK GROWTH In applying the ASME Section XI (Reference 3) acceptance criteria, the final flaw size (af) used is defined as the flaw size to which the detected or postulated flaw is calculated to grow to in a specific time period, which in the evaluation herein, is until the end of the plant design life (i.e., 80 years). For the RCL CASS piping components in pressurized water reactors, only fatigue crack growth needs to be considered because three conditions must exist simultaneously for stress corrosion cracking to occur in stainless steel piping components: high tensile stresses, susceptible material, and an environment that is conducive to stress corrosion cracks. Although some residual stress and some degree of material susceptibility exists in any stainless-steel piping component, the reactor coolant water chemistry is monitored and maintained within very specific limits. Contaminant concentrations are kept below the thresholds known to be conducive to stress corrosion cracking with the major water chemistry control standards being included in the plant operating procedures as a condition for plant operation. The RCL CASS piping component material in pressurized water reactors is therefore unlikely to be susceptible to stress corrosion cracking and therefore only fatigue crack growth needs to be considered.
To determine fatigue crack growth for the susceptible CASS piping components, the loadings used consist of loads due to thermal expansion, deadweight, pressure, residual stresses and thermal transient loads. The design transients shown in Table 2-3 are used in the fatigue crack growth analysis. The analysis procedure involves postulating an initial flaw at the susceptible piping components and predicting the flaw growth due to an imposed series of loading transients. The input required for a fatigue crack growth analysis is basically the information necessary to calculate the crack tip stress intensity factor range (KI), which depends on the geometry of the crack, its surrounding structure, and the range of applied stresses in the crack area.
The stress intensity factor calculations were performed for semi-elliptical inside surface axial and circumferential flaws using the stress intensity factor expressions from Reference 10 and Reference 11, respectively. The fatigue crack growth rate for embedded and outside surface flaws in an air environment is lower than that for inside surface flaws exposed to the Pressurized Water Reactor (PWR) water environment. Therefore, embedded flaw and outside surface flaw evaluations are conservatively bounded by the inside surface flaw tolerance analysis in this report. Stress intensity factors can be expressed in the general form as follows:
Where:
a:
Crack depth c:
Half crack length around surface t:
Thickness of pipe R
Inside radius Angular position
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 5-2 WCAP-18900-NP November 2024 Revision 0 Gj:
G0, G1, G2, G3 are boundary correction factors Q:
The shape factor of an elliptical crack, Q, is approximated by: Q = 1 + 1.464(a/c)1.65 for a/c 1 or Q = 1 + 1.464(c/a)1.65 for a/c > 1.
Once KI is calculated, the growth for inside surface flaws due to a particular stress cycle can be calculated using the applicable fatigue crack growth reference curves for stainless steel in PWR water environments.
To represent the PWR water environment for stainless steel, an environment factor of 2 for a PWR environment (Reference 7) was applied to the reference fatigue crack growth curve for austenitic stainless steel in an air environment, as provided in Appendix C of ASME Section XI. The incremental growth from fatigue crack growth is then added to the original crack size, and the analysis proceeds to the next cycle or transient. The procedure is continued in this manner until all the analytical transients known to occur in the 80 years of operation have been analyzed. The fatigue crack growth equation has the following generic form:
Where:
=
Crack growth rate, inches per cycle Co
=
CS C
=
10^[-10.009 + 8.12x10-4T - 1.13x10-6T2 + 1.02x10-9T3],
T in °F S
=
S = 1.0 for R 0 S = 1+1.8R for 0 < R 0.79 S = -43.35+57.97R for 0.79 < R 1.0 n
=
material property slope (= 3.30)
R
=
Kmin/Kmax KI
=
stress intensity factor range, ksiin E
=
environmental factor (per Reference 7)
(E = 1.0 for air environment, and E = 2.0 for PWR environment)
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Westinghouse Non-Proprietary Class 3 6-1 WCAP-18900-NP November 2024 Revision 0 6
FLAW TOLERANCE EVALUATION Axial and circumferential surface flaws are defined respectively as flaws oriented along and perpendicular to the centerline axis of the piping components of interest. Two basic dimensionless parameters, flaw shape parameter (a/) and flaw depth parameter (a/t) can fully address the characteristics of a surface flaw, where:
t = wall thickness a = flaw depth
= flaw length Based on the screening criteria in NUREG-2191 (Reference 2) and the Grimess Letter (Reference 1), all RCL elbows in H.B. Robinson Unit 2 are potentially susceptible to thermal aging while the straight piping components are not susceptible to thermal aging. As a result, flaw tolerance evaluations were performed independently on the potentially susceptible elbows with elbow-specific material properties, geometry, and stresses. The bounding elbow results are reported herein. The flaw tolerance charts for the susceptible elbow components in the RCL are shown in Figure 6-1 through Figure 6-6 for both axial and circumferential flaws.
The purpose of these flaw tolerance charts is to identify the maximum acceptable initial flaw size for a given plant operation duration. Note that the flaw charts in Figure 6-1 through Figure 6-6 were developed based on acceptance criteria per ASME Section XI Appendix C.
The results presented in Figure 6-1 through Figure 6-6 represent the limiting results for inside surface, outside surface and embedded flaws which are characterized in accordance with IWA-3300 of the ASME Section XI Code. For a typical flaw tolerance chart, the flaw shape parameter (a/) is plotted as the abscissa from 0.1 to 0.5 and the flaw depth parameter (a/t) expressed as a ratio of the through-wall thickness is plotted as the ordinate from 0.0 to 0.8. Therefore, the flaw tolerance charts in Figure 6-1 through Figure 6-6 encompass various postulated flaw cases based on different aspect ratios (ranging in /a from 2 to 10). The allowable flaw size curves show the maximum acceptable initial flaw depth beyond which repair is required for continued service. The design transient cycles used in the evaluation bound the projected cycles for 80 years of plant operation. The curves in Figure 6-1 through Figure 6-6 are for a service life of up to 80 years from the time that a flaw is discovered, based on fatigue crack growth calculations. Any flaw which falls below the allowable flaw size curve in these figures is acceptable in accordance with the ASME Section XI Appendix C acceptance criteria for up to 80 years.
The following is an explanation of how to use the flaw tolerance charts, using Figure 6-1 as an example.
Assume a hypothetical axial flaw in an elbow on the hot leg with aspect ratio of 2 (or a/ of 0.5) and flaw depth of 30% through the wall thickness is to be evaluated per ASME Section XI. The flaw dimensions of a/ = 0.5 and a/t = 0.3 are plotted on Figure 6-1 in order to determine flaw tolerance evaluation of the axial flaw in the hot leg. This particular flaw falls below the allowable initial flaw size curve in Figure 6-1; the allowable initial flaw size curve which is shown in blue in Figure 6-1 demonstrates the largest initial flaw size (a/t) that will be acceptable for up to 80 years of fatigue crack growth per the guidance of ASME Section XI. Thus, the hypothetical axial flaw that is 30% of the wall is demonstrated to be flaw tolerant for at least 80 years. Thus, in general, any flaw with a combination of flaw size (a/t) and aspect ratio that is below the allowable initial flaw curve is flaw tolerant for at least 80 years.
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Westinghouse Non-Proprietary Class 3 6-2 WCAP-18900-NP November 2024 Revision 0 As an additional illustration, using the curves shown in Figure 6-1 through Figure 6-6, the maximum acceptable initial flaw depths for the susceptible RCL CASS piping components for a service life of up to 80 years are summarized in Table 6-1 as a percentage of the through-wall thickness for a hypothetical flaw with an aspect ratio (/a) of 6 (or a/ of 0.167). An aspect ratio of 6 is frequently considered for flaw tolerance analysis of hypothetical flaws in ASME Section XI. The maximum acceptable initial flaw sizes for all other analyzed aspect ratios can be obtained directly from Figure 6-1 through Figure 6-6 for the susceptible CASS piping components. The allowable end-of-evaluation period flaw sizes shown in Table 6-1 (for the example aspect ratio /a of 6) were determined in accordance with the flaw evaluation guidelines and acceptance criteria contained in ASME Section XI Appendix C using the piping loads from Table 2-2. The maximum acceptable initial flaw sizes shown in Table 6-1 were obtained by subtracting the fatigue crack growth for 80 years of service life from the maximum allowable end-of-evaluation period flaw sizes. In Table 6-1, the difference between the acceptable initial flaw sizes and the maximum allowable end-of-evaluation period flaw sizes is the amount of fatigue crack growth over 80 years of plant life. The magnitude of FCG is dependent on the geometry, temperature, severity of the design transients, and the range of stress intensity factor at the location of interest.
Table 6-1 below provides example acceptable initial axial and circumferential flaw sizes for an aspect ratio of 6. Any flaw smaller than the values listed in the table is acceptable for 80 years. The large magnitude of these flaw sizes demonstrate that a significant amount of plastic collapse would be necessary to cause structural integrity concern for the CASS components. These large flaw sizes would have been originally detected during fabrication of the components and subsequently repaired. Furthermore, operational experience has demonstrated that these types of large flaw sizes are not present in the CASS components for PWRs. Based on the results tabulated in Table 6-1 for a hypothetical postulated flaw with an aspect ratio of 6, the most limiting maximum acceptable initial flaw depth in the susceptible CASS piping components of the RCL is in the hot leg and crossover leg for an axial flaw that is 37% through the wall thickness. [
]a,c,e The "Acceptable Initial Flaw Size" in Table 6-1 represent the largest allowable flaw sizes that will take 80 years to grow to the maximum allowable end-of-evaluation period flaw size. As a result, the lowest value for "Acceptable Initial Flaw Size" is bounding (i.e., 37% flaw depth through the wall thickness compared to, for example, 48% for hot leg, circumferential flaw). The "Maximum Allowable End-of-Evaluation Period Flaw Size" in Table 6-1 represents the largest flaw size that will result in plastic collapse of the piping component calculated per ASME Section XI Appendix C. To reiterate, the difference between the acceptable initial flaw sizes and the maximum allowable end-of-evaluation period flaw sizes in Table 6-1 is the amount of fatigue crack growth over 80 years of plant life. Thus, as-found flaw sizes less than the "Acceptable Initial Flaw Size" will take longer than 80 years to reach a critical flaw size that will result in plastic collapse of the component.
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 6-3 WCAP-18900-NP November 2024 Revision 0 Table 6-1: Acceptable Initial Flaw Sizes (% Through-Wall Thickness) for Susceptible CASS Elbow Components (Aspect Ratio = 6, For a Service Life of 80 years)
Location Axial Flaw Circumferential Flaw Acceptable Initial Flaw Size Maximum Allowable End-of-Evaluation Period Flaw Size Acceptable Initial Flaw Size Maximum Allowable End-of-Evaluation Period Flaw Size Hot Leg 37%
62%
48%
75%
Crossover Leg 37%
41%
67%
75%
Cold Leg 50%
58%
67%
75%
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 6-4 WCAP-18900-NP November 2024 Revision 0 Figure 6-1: Axial Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Hot Leg 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Flaw Depth / Wall Thickness (a/t)
Flaw Shape - a/
Acceptable Unacceptable 80 Years
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 6-5 WCAP-18900-NP November 2024 Revision 0 Figure 6-2: Circumferential Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Hot Leg 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Flaw Depth / Wall Thickness (a/t)
Flaw Shape - a/
Acceptable Unacceptable 80 Years
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 6-6 WCAP-18900-NP November 2024 Revision 0 Figure 6-3: Axial Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Crossover Leg 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Flaw Dpeth / Wall Thickness (a/t)
Flaw Shape - a/
Unacceptable Acceptable 80 Years
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 6-7 WCAP-18900-NP November 2024 Revision 0 Figure 6-4: Circumferential Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Crossover Leg 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Flaw Depth / Wall Thickness (a/t)
Flaw Shape - a/
Acceptable Unacceptable 80 Years
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 6-8 WCAP-18900-NP November 2024 Revision 0 Figure 6-5: Axial Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Cold Leg 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Flaw Depth / Wall Thickness (a/t)
Flaw Shape - a/
Acceptable Unacceptable 80 Years
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 6-9 WCAP-18900-NP November 2024 Revision 0 Figure 6-6: Circumferential Flaw Tolerance Chart for Susceptible CASS Elbow Components in the Cold Leg 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 Flaw Depth / Wall Thickness (a/t)
Flaw Shape - a/
Acceptable Unacceptable 80 Years
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 7-1 WCAP-18900-NP November 2024 Revision 0 7
SUMMARY
AND DISCUSSION The pre-service fracture toughness of cast austenitic stainless steel has been found to be very high at operating temperatures. However, cast austenitic stainless steel may be susceptible to thermal aging after prolonged exposure to the reactor coolant temperature. Thermal aging of cast austenitic stainless-steel results in embrittlement, that is, a decrease in the ductility, impact strength and fracture toughness, and an increase in hardness and tensile strength of the material. Depending on the material composition, the Charpy impact energy of a cast austenitic stainless-steel component could decrease to a smaller fraction of its original value after prolonged exposure to the reactor coolant temperature during service.
The primary reactor coolant loop elbow components in H.B. Robinson Unit 2 are constructed from CASS A-351 CF8M material, while the straight piping is constructed from A-376 TP316 material. Susceptibility of RCL CASS piping components in H.B. Robinson Unit 2 was determined using the screening criteria given in NUREG-2191 (Reference 2) and the Grimess Letter (Reference 1) based on the molybdenum content, casting method, and ferrite content. The straight piping is determined to be not susceptible to thermal aging in Section 3.2 and is not required to be included in the flaw tolerance analysis. In determining susceptibility of the CASS elbow components to thermal aging, the delta ferrite content is estimated using Hulls Equivalent Factor in NUREG/CR-4513, Revision 1 (Reference 4). Based on the screening criteria for thermal aging susceptibility, all RCL elbows are potentially susceptible to thermal aging and are considered in the flaw tolerance evaluations completed herein.
In accordance with the guidelines given in the NUREG-2191 and the Grimess Letter, the H.B. Robinson Unit 2 susceptible CASS elbow components can be evaluated using the evaluation procedures and acceptance criteria in paragraph IWB-3640 of the ASME Section XI Code for submerged arc welds.
Bounding flaw tolerance charts were also generated for the susceptible CASS elbow components in the RCL as shown in Figure 6-1 through Figure 6-6 for both axial and circumferential flaws. The results presented in Figure 6-1 through Figure 6-6 represent the limiting results for inside surface, outside surface and embedded flaws. The purpose of these flaw tolerance charts is to identify the maximum acceptable initial flaw size for a service life of up to 80 years. Any flaw which falls below the allowable flaw size curve is acceptable in accordance with the IWB-3640 acceptance criteria for up to 80 years. Based on the flaw tolerance analysis results of the susceptible CASS elbow components in H.B. Robinson Unit 2, it is concluded that even with thermal aging, the susceptible CASS elbow components are flaw tolerant for up to 80 years of service.
For example, based on the results tabulated in Table 6-1, for a hypothetical postulated axial flaw with an aspect ratio of 6, the maximum acceptable initial flaw depth in the susceptible CASS piping components of the RCL is in the hot leg and crossover leg for an axial flaw that is 37% through the wall thickness.
[
]a,c,e The maximum acceptable initial flaw depths are even larger for a hypothetical postulated circumferential flaw as tabulated in Table 6-1. Therefore, the graphical results per Figure 6-1 through Figure 6-6 demonstrate that the RCL components are highly flaw tolerant, since a significantly large flaw size is necessary to cause structural integrity concern for the CASS components.
These large flaw sizes would have been originally detected during fabrication of the components and subsequently repaired. Furthermore, operational experience has demonstrated that these types of large flaw sizes are not present in the CASS components for PWRs.
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 7-2 WCAP-18900-NP November 2024 Revision 0 In conclusion, this report presents a plant-specific flaw tolerance evaluation which demonstrates that the RCL elbow components at H.B. Robinson Unit 2 have adequate fracture toughness and are flaw tolerant for up to 80 years of service life.
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
Westinghouse Non-Proprietary Class 3 8-1 WCAP-18900-NP November 2024 Revision 0 8
REFERENCES
- 1. Letter from Christopher I. Grimes, U.S. Nuclear Regulatory Commission, License Renewal and Standardization Branch, to Douglas J. Walters, Nuclear Energy Institute, License Renewal Issue No. 98-0030, Thermal Aging Embrittlement of Cast Austenitic Stainless Steel Components, May 19, 2000. [ADAMS Accession No. ML003717179]
- 2. U.S. Nuclear Regulatory Commission, NUREG-2191, Generic Aging Lessons Learned for Subsequent License Renewal (GALL-SLR) Report - Final Report, July 2017.
- 3. ASME Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 2017 Edition.
- 4. O.K. Chopra, Estimation of Fracture Toughness of Cast Stainless Steels During Thermal Aging in LWR Systems, NUREG/CR-4513, Revision 1, U. S. Nuclear Regulatory Commission, Washington DC, August 1994. [Adams Accession No. ML052360554]
- 5. O.K. Chopra, Estimation of Fracture Toughness of Cast Stainless Steels during Thermal Aging in LWR Systems, NUREG/CR-4513, Revision 2, U.S. Nuclear Regulatory Commission, Washington D.C., May 2016, including Errata, March 15, 2021. [Adams Accession No. ML16145A082]
- 6. [
] a,c,e
- 7. Evaluation of Flaws in Austenitic Steel Piping, Trans ASME, Journal of Pressure Vessel Technology, Vol. 108, August 1986, pp. 352-366.
- 8. ASME Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 2019 Edition.
- 9. U.S. Nuclear Regulatory Commission, Draft NUREG-2191, Revision 1, Vol. 2, Generic Aging Lessons Learned for Subsequent License Renewal (GALL-SLR) Report, July 2023. [ADAMS Accession No. ML23180A188]
- 10. S. R. Mettu, I. S. Raju, "Stress Intensity Factors for Part-through Surface Cracks in Hollow Cylinders," Jointly developed under Grants NASA-JSC 25685 and Lockheed ESC 30124, Job Order number 85-130, Call number 96N72214 (NASA-TM-111707), July 1992.
- 11. S. Chapuliot, M. H. Lacire, and P. Le. Delliou, Stress Intensity Factors for Internal Circumferential Cracks in Tubes Over a Wide Range of Radius Over Thickness Ratios, ASME PVP Vol. 365, 1998.
- 12. [
] a,c,e
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Westinghouse Non-Proprietary Class 3 8-2 WCAP-18900-NP November 2024 Revision 0
- a. [
] a,c,e
- b. [
] a,c,e
- 13. H.B. Robinson Steam Electric Plant Unit 2 (HBR2) Updated Final Safety Analysis Report (FSAR). [ADAMS Accension Number: ML23145A162]
- This record was final approved on 11/23/2024 09:58:07. (This statement was added by the PRIME system upon its validation)
WCAP-18900-NP Revision 0 Non-Proprietary Class 3
- This page was added to the quality record by the PRIME system upon its validation and shall not be considered in the page numbering of this document.**
Approval Information Author Approval Coleman Joshua A Nov-22-2024 15:29:15 Reviewer Approval Udyawar Anees Nov-22-2024 15:33:36 Verifier Approval Rizzilli Maria A Nov-22-2024 16:38:44 Manager Approval Iddings Remington Nov-23-2024 09:58:07 Files approved on Nov-23-2024