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Report No. 0800692.404, Rev. 1, Design Report for Preemptive Repairs of Hot Leg Alloy 600 Components, San Onofre Nuclear Generating Station, Units 2 & 3
ML092450080
Person / Time
Site: San Onofre  Southern California Edison icon.png
Issue date: 08/03/2009
From: Giannuzzi A
Structural Integrity Associates
To:
Office of Nuclear Reactor Regulation, Welding Services
References
0800692.404, Rev 1
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Report No.: 0800692.404 Revision No.: I Project No.: 0800692 August 2009 Design Report for Preemptive Repairs of Hot Leg Alloy 600 Components San Onofre Nuclear Generating Station (SONGS), Units 2 and 3 Prepared. for:

Welding Services Inc.

Southern California Edison (SCE)

(Contract No. 47805)

Prepared by."

Structural Integrity Associates, Inc.

San Jose. CA

~\\

A h01\\JkA 24A0,N Prepared by:

Reviewed b*y:

Approved by:

A. J. Giannuzzi 11ý-

(-< t PDate:

August 3. 2009

____t-Date: August 3. 2009 Date: August 3. 2009 R. A. Mattson. P. E.

U Structural Integrity Associates, Inc.

Prepared by:

Reviewed by:

Approved by:

Report No.: 0800692.404 Revision No.: 1 Project No.: 0800692 August 2009 Design Report for Preemptive Repairs of Hot Leg Alloy 600 Components San Onofre Nuclear Generating Station (SONGS), Unit~ 2 and 3 Preparedfor:

Welding Services Inc.

Southern California Edison (SCE)

(Contract No.4 7805)

Prepared by:

Structural Integrity Associates, Inc.

San Jose, CA AUf!ust 3. 2009 Date: August 3.2009 Date: AUf!ust 3. 2009 l) Struclurallntegrity Associates, Inc.

REVISION CONTROL SHEET Document Number:

0800692.404

Title:

Design Report for Preemptive Repairs of Hot Lei Alloy 600 Components, San Onofre Nuclear Generating Station (SONGS), Units 2 and 3 Client: Welding Services Inc. / Southern SI Project Number:

0800692 California Edison (SCE)

Sections Pages Revision Date Comments 1.0 1 1-2 0

6/9/09 Initial Issue 2.0 2 2-7 3.0 3-1 13 4.0 4-1 6 5.0 5-1-5-6 6.0 6-1 6 7.0 7-1-7-2 8.0 8-1-8-3 9.0 9-1-9-2 10.0 10-1-10-2 11.0 11-1-11-2 1.0 1-1 1

8/3/09 Added paragraph to Section 1 to remove "Priority Information" callouts on all pages W

Structural Integrity Associates, Inc.

REVISION CONTROL SHEET Document Number:-----'0=8"-"0'-"0:..oe6.=....92""'.:...;4-"-04-'--_________________ _

Title:

Design Report for Preemptive Repairs of Hot Leg Alloy 600 Components, San Onofre Nuclear Generating Station (SONGS), Units 2 and 3 Client: Welding Services Inc. / Southern California Edison (SCE)

SI Project Number:

0800692 Sections Pages Revision Date Comments 1.0 1 1-2

° 6/9/09 Initial Issue 2.0 2 2-7 3.0 3-1-3-13 4.0 4 4-6 5.0 5-1-5-6 6.0 6 6-6 7.0 7-1 2 8.0 8-1-8-3 9.0 9 9-2 10.0 10 10-2 11.0 11-1-11-2 1.0 1-1 1

8/3/09 Added paragraph to Section 1 to remove "Priority Information" call outs on all pages l) Structural Integrity Associates, Inc.

Professional Enaineer Certification Statement "Desiggn Report for Preemptive Repairs of Hot Leg Alloy 600 Components, San Onofre Nuclear Generating Station (SONGS), Units 2 and 3" 1, Richard A. Mattson, being a duly licensed professional engineer under the laws of the State of California, certif, that this document was reviewed by me, and that this document meets the requirements of ASME Code,Section XI and Section III (Editions and Addenda as referenced in the individual calculations), and the San Onofre Nuclear Generating Station (SONGS), Units 2 and 3 Relief Request, RR-ISI-3-27, Revision 1, which is based on the requirements of Code Case N-504-2, and Relief Request RR-1SI-3-28, Revision 1, which is based on the requirements of Code Case N-638-1, all as applicable to the specific scope of this report. This report is supplementary to the governing Stress Reports for the systems and components described herein, and does not invalidate those reports. I further certify that this document is correct and complete to the best of my knowledge and belief, and that I am competent to review this document.

Richard A. Mattson, P.E.

State of California Registration Number: C25664

~ESSIO Date: August 3, 2009 0800692.404, Rev,. 1 Structural Integrity Associates, Inc.

Professional Engineer Certification Statement "Design Report for Preemptive Repairs of Hot Leg Alloy 600 Components, San Onofre Nuclear Generating Station (SONGS), Units 2 and 3" 1, Richard A. Mattson, being a duly licensed professional engineer under the laws ofthe State of California, certify that this document was reviewed by me, and that this document meets the requirements of ASME Code,Section XI and Section III (Editions and Addenda as referenced in the individual calculations), and the San Onofre Nuclear Generating Station (SONGS), Units 2 and 3 Relief Request, RR-ISI-3-27, Revision 1, \\vhjch is based on the requirements of Code Case N-504-2, and Relief Request RR-1S1-3-28, Revision 1, which is based on the requirements of Code Case N-63 8-1, all as applicable to the specific scope of this report. This report is supplementary to the governing Stress Reports for the systems and components described herein, and does not invalidate those reports. I further certify that this document is correct and complete to the best of my knowledge and belief, and that I am competent to review this document.

0800692.404, Rev. 1 Richard A. Mattson; P.E.

State of California Registration Number: C25664 Date: August 3, 2009

!(j Structural Integrity Associates, Inc.

Table of Contents Section Page

1.0 INTRODUCTION

1-1 1.1 Background..................................................................................................................

1-1 1.2 W eld Overlay Repairs.................................................................................................

1-1 1.3 Objectives and Report Organization............................................................................

1-2 2.0 W ELD OVERLAY DESIGN........................................................................................

2-1 2.1 Weld Overlay Application........................................

2-1 2.2 Criteria for Design of Full Structural W eld Overlay Repairs......................................

2-2 2.3 W eld Overlay Structural Sizing...................................................................................

2-3 2.3.1 Weld Overlay Thickness...........................................................................................

2-3 2.3.2 Weld Overlay Length...............................................................................................

2-4 2.4 Comparison with Field M easurements........................................................................

2-4 3.0 RESIDUAL STRESS ANALYSES...............................................................................

3-1 3.1 Background.................................................................................................................. 3-1 3.2 Technical Approach....................................................................................................

3-1 3.3 Residual Stress Analysis Results.................................................................................

3-3 4.0 EVALUATION OF WELD OVERLAY EFFECTS ON PIPING SYSTEMS......... 4-1 4.1 Background...................................................................................................................

4-1 4.2 Evaluation of W eld Overlay Shrinkage Stresses.........................................................

4-2 4.3 Evaluation of the Effect of W eld Overlay W eight.......................................................

4-3 4.3.1 D ea d W eig h t.............................................................................................................

4 -3 4.3.2 Dynamic Response................................................................................

.................... 4-4 5.0 CRACK GROW TH EVALUATIONS.........................................................................

5-1 5.1 Background..................................................................................................................

5-1 5.2 Technical Approach....................................................................................................

5-1 5.3 Crack Growth Results..................................................................................................

5-3 5.3.1 Hot Leg Shutdown Cooling Nozzle..........................................................................

5-3 5.3.2 Hot Leg Surge Nozzle-Unit 2.....................................

5-4 5.3.3 Hot Leg Surge Nozzle-Unit 3...................................................................................

5-4 5.3.4 Hot Leg Drain Nozzle..............................................................................................

5-5 0800692.404, Rev. 1 iv Structural Integrity Associates, Inc.

Table of Contents Section Page

1.0 INTRODUCTION

..................................................................... ;.................................... 1-1 1.1 Background.................................................................................................................. 1-1 1.2 Weld Overlay Repairs.................................................................................................. 1-1 1.3 Objectives and Report Organization............................................................................ 1-2 2.0 WELD OVERLAY DESIGN........................................................................................ 2-1 2.1

  • Weld Overlay Application......................... ~................................................................. 2-1 2.2 Criteria for Design of Full Structural Weld Overlay Repairs...................................... 2-2 2.3 Weld Overlay Structural Sizing................................................................................... 2-3 2.3.1 Weld Overlay Thickness........................................................................................... 2-3 2.3.2 Weld Overlay Length............................................................................................... 2-4 2.4 Comparison with Field Measurements........................................................................ 2-4 3.0 RESIDUAL STRESS ANALySES............................................................................... 3-1 3.1 Background................................................................................................................... 3-1 3.2 Technical Approach...................................................................................................... 3-1 3.3 Residual Stress Analysis Results................................................................................. 3-3 4.0 EVALUATION OF WELD OVERLAY EFFECTS ON PIPING SYSTEMS......... 4-1 4.1 Background.................................................................................................................. 4-1 4.2 Evaluation of Weld Overlay Shrinkage Stresses......................................................... 4-2 4.3 Evaluation of the Effect of Weld Overlay Weight....................................................... 4-3 4.3.1 Dead Weight............................................................................................................. 4-3 4.3.2 Dynamic Response................................................................................................... 4-4 5.0 5.1 CRACK GROWTH EVALUATIONS......................................................................... 5-1 Background.................................................................................................................. 5-1 5.2 Technical Approach..................................................................................................... 5-1 5.3 Crack Growth Results.................................................................................................. 5-3 5.3.1 Hot Leg Shutdown Cooling Nozzle.......................................................................... 5-3 5.3.2 Hot Leg Surge Nozzle-Unit 2.......................................................... :........................ 5-4 5.3.3 Hot Leg Surge Nozzle-Unit 3................................................................................... 5-4 5.3.4 Hot Leg Drain Nozzle.............................................................................................. 5-5 0800692.404, Rev. 1 IV tJ Structural Integrity Associates, Inc.

6.0 ASME SECTION III STRESS ANALYSES...............................................................

6-1 6.1 Background..................................................................................................................

6-1 6.2 D esign Criteria............................................................................................................

6-1 6.3 Technical Approach.....................................................................................................

6-1 6.4 Results of Analyses......................................................................................................

6-3 6.4.1 H ot Leg Shutdown Cooling N ozzle.........................................................................

6-3 6.4.2 H ot Leg Surge Nozzle-Unit 2...................................................................................

6-3 6.4.3 H ot Leg Surge Nozzle-Unit 3..................................................................................

6-4 6.4.4 H ot Leg D rain Nozzle..............................................................................................

6-4 6.5 Concluding Rem arks....................................................................................................

6-4 7.0 RECONCILIATION OF CODE-OF-RECORD TO LATER CODE EDITION.... 7-1 7.1 D esign..........................................................................................................................

7-1 7.2 Fabrication...................................................................................................................

7-1 7.3 Exam ination.................................................................................................................

7-2 7.4 M aterials......................................................................................................................

7-2 7.5 Conclusion...................................................................................................................

7-2 8.0 EVALUATION OF AS-BUILT CONDITIONS.........................................................

8-1 8.1 N CR N o.08-223..........................................................................................................

8-1 8.2 N CR N o.09-281..........................................................................................................

8-2 8.3 N CR N o.09-282..........................................................................................................

8-3 9.0 SUM M AR Y AND CO N CLU SIO N S............................................................................

9-1 10.0 REFEREN CES.............................................................................................................

10-1 11.0 APPENDICES - STRUCTURAL INTEGRITY ASSOCIATES CALCULATION PACKAGES AND DESIGN DRAWINGS................................................................

11-1 0800692.404, Rev. 1 V

Structural Integrity Associates, Inc.

6.0 ASME SECTION III STRESS ANALYSES............................................................... 6-1 6.1 Background.................................................................................................................. 6-1 6.2 Design Criteria............................................................................................................. 6-1 6.3 Technical Approach..................................................................................................... 6-1 6.4 Results of Analyses...................................................................................................... 6-3 6.4.1 Hot Leg.Shutdown Cooling Nozzle.......................................................................... 6-3 6.4.2 Hot Leg Surge Nozzle-Unit 2................................................................................... 6-3 6.4.3 Hot Leg Surge Nozzle-Unit 3................................................................................... 6-4 6.4.4 Hot Leg Drain Nozzle.............................................................................................. 6-4 6.5 Concluding Remarks.................................................................................................... 6-4 7.0 RECONCILIATION OF CODE-OF-RECORD TO LATER CODE EDITION.... 7-1 7.1 Design.......................................................................................................................... 7-1 7.2 Fabrication................................................................................................................... 7-1 7.3 Examination................................................................................................................. 7-2 7.4 Materials...................................................................................................................... 7-2 7.5 Conclusion................................................................................................................... 7-2 8.0 EVALUATION OF AS-BUILT CONDITIONS......................................................... 8-1 8.1 NCR No.08-223.......................................................................................................... 8-1 8.2 NCR No.09-281.......................................................................................................... 8-2 8.3 NCR No.09-282.......................................................................................................... 8-3 9.0

SUMMARY

AND CONCLUSIONS............................................................................ 9-1

10.0 REFERENCES

............................................................................................................. 10.;1 11.0 APPENDICES - STRUCTURAL INTEGRITY ASSOCIATES CALCULATION PACKAGES AND DESIGN*DRA WINGS................................................................ 11-1 0800692.404, Rev. 1 v

tJ Structural Integrity Associates, Inc.

List of Tables Table Page Table 2-1: Weld Overlay Minimum Structural Thickness and Length R equirem ents-U nit 2 and U nit 3.............................................................................

2-5 Table 2-2: Post-Weld Overlay Minimum As-Built Dimensions-Unit 2.....................................

2-6 Table 2-3: Post-Weld Overlay Minimum As-Built Dimensions-Unit 3.....................................

2-7 Table 4-1: Weld Overlay Shrinkage Measurements-Unit 2.......................................................

4-5 Table 4-2: Weld Overlay Shrinkage Measurements-Unit 3.......................................................

4-5 Table 4-3: Design Maximum Overlay Weight Summary-Unit 2 and Unit 3.............................

4-6 Table 5-1: Limiting Crack Growth Results - Hot Leg Nozzles..................................................

5-6 Table 6-1: Limiting Stress Results for Hot Leg Shutdown Cooling Nozzle..............................

6-5 Table 6-2: Limiting Stress Results for Hot Leg Surge Nozzle-Unit 2........................................

6-5 Table 6-3: Limiting Stress Results for Hot Leg Surge Nozzle-Unit 3........................................

6-6 Table 6-4: Limiting Stress Results for Hot Leg Drain Nozzle...................................................

6-6 0800692.404, Rev. 1 vi Structural Integrity Associates, Inc.

List of Tables Table 2-1: Weld Overlay Minimum Structural Thickness and Length Requirements-Unit 2 and Unit 3.............................................................................. 2-5 Table 2-2: Post-Weld Overlay Minimum As-Built Dimensions-Unit 2..................................... 2-6 Table 2-3: Post-Weld Overlay Minimum As-Built Dimensions-Unit 3..................................... 2-7 Table 4-1: Weld Overlay Shrinkage Measurements-Unit 2....................................................... 4-5 Table 4-2: Weld Overlay Shrinkage Measurements-Unit 3....................................................... 4-5 Table 4-3: Design Maximum Overlay Weight Summary-Unit 2 and Unit 3............................. 4-6 Table 5-1: Limiting Crack Growth Results - Hot Leg Nozzles.................................................. 5-6 Table 6-1: Limiting Stress Results for Hot Leg Shutdown Cooling Nozzle.............................. 6-5 Table 6-2: Limiting Stress Results for Hot Leg Surge Nozzle-Unit 2........................................ 6-5 Table 6-3: Limiting Stress Results for Hot Leg Surge Nozzle-Unit 3........................................ 6-6 Table 6-4: Limiting Stress Results for Hot Leg Drain Nozzle................................................... 6-6 0800692.404, Rev. 1 VI l) Structural Integrity Associates, Inc.

List of Figures Figure*Pg

.Page Figure 3-1:

Figure 3-2:

Figure 3-3:

Figure 3-4:

Figure 3-5:

Figure 3-6:

Figure 3-7:

Figure 3-8:

Figure 3-9:

Lumped Weld Nuggets for 16" Hot Leg Shutdown Cooling Nozzle R esidual Stress A nalysis.........................................................................................

3-5 Lumped Weld Nuggets for 12" Hot Leg Surge Nozzle Residual Stress A nalysis, U nit 2............................................................................................

3-6 Lumped Weld Nuggets for 12" Hot Leg Surge Nozzle Residual Stress A nalysis, U nit 3............................................................................................

3-7 Lumped Weld Nuggets for 2" Hot Leg Drain Nozzle Residual Stress Analysis..... 3-8 Post ID Weld Repair Residual Stress in the Unit 2 12" Hot Leg Surge N ozzle at 70 'F........................................................................................................

3-9 Post-WOL Residual Stresses in the Unit 2 12" Hot Leg Surge N ozzle at 70 'F......................................................................................................

3-10 Applied Post Weld Overlay Residual Stress in the Unit 2 12" Hot Leg Surge Nozzle at 61 1F and 2235 psig....................................................

3-11 ID Surface Axial Stresses in the Unit 2 12" Hot Leg Surge Nozzle, P re-and P ost-overlay.......................................................................

.................... 3-12 ID Surface Hoop Stresses in the Unit 2 12" Hot Leg Surge Nozzle, P re-and P ost-overlay............................................................................................

3-13 4, Rev. 1 vii Structural Integrity Associates, Inc.

0800692.40' List of Figures Figure Figure 3-1: Lumped Weld Nuggets for 16" Hot Leg Shutdown Cooling Nozzle Residual Stress Analysis......................................................................................... 3-5 Figure 3-2: Lumped Weld Nuggets for 12" Hot Leg Surge Nozzle Residual Stress Analysis, Unit 2............................................................................................ 3-6 Figure 3-3: Lumped Weld Nuggets for 12" Hot Leg Surge Nozzle Residual Stress Analysis, Unit 3............................................................................................ 3-7 Figure 3-4: Lumped Weld Nuggets for 2" Hot Leg Drain Nozzle Residual Stress Analysis..... 3-8 Figure 3-5: Post ID Weld Repair Residual Stress in the Unit 2 12" Hot Leg Surge Nozzle at 70°F........................................................................................................ 3-9 Figure 3-6: Post-WOL Residual Stresses in the Unit 2 12" Hot Leg Surge Nozzle at 70°F...................................................................................................... 3-10 Figure 3-7: Applied Post Weld Overlay Residual Stress in the Unit 2 12" Hot Leg Surge Nozzle at 611°F and 2235 psig.................................................... 3-11 Figure 3-8: ID Surface Axial Stresses in the Unit 2 12" Hot Leg Surge Nozzle, Pre-and Post-overlay....................................................................... ;.................... 3-12 Figure 3-9: ID Surface Hoop Stresses in the Unit 2 12" Hot Leg Surge Nozzle, Pre-and Post-overlay............................................................................................ 3-13 0800692.404, Rev. 1 Vll

!S) Structural Integrity Associates, Inc.

1.0 INTRODUCTION

1.1 Background

Southern California Edison (SCE) is applying full structural weld overlays (FSWOLs) on dissimilar metal butt welds (DMWs) of the hot leg components listed below at the San Onofre Nuclear Generating Station (SONGS), Units 2 and 3, to eliminate dependence upon the Alloy 82/182 welds as pressure boundary welds, and to mitigate any potential primary water stress corrosion cracking (PWSCC) in these welds in the future.

This report summarizes the structural evaluations of preemptive, full structural weld overlay designs for one Hot Leg Surge Nozzle, one Hot Leg Shutdown Cooling Nozzle and one Hot Leg Drain Nozzle for each unit.

Revision 1 of this Design Report removes all references to "Proprietary Information." No content changes were made.

1.2 Weld Overlay Repairs Weld overlays have been used routinely in U.S. BWRs and PWRs to repair flaws associated with stress corrosion cracking. The process is an ASME Code approved repair method under the Relief Requests [2], which are based on ASME Code Case N-504-2 and N-638-1 [1]. As an alternative to post weld heat treatment (PWHT) of the nozzle material, the overlays are applied with the ambient temperature temperbead welding technique, using Gas Tungsten Arc Welding (GTAW) with selective and carefully controlled weld bead placement and heat input, in accordance with the Relief Requests [2], which are based on ASME Code Case N-504-2 and N-638-1 [1]. Nickel alloy weld filler metal is utilized for the weld overlays for material compatibility with the underlying pipe, safe end, and nozzle materials. The specified welding material for the weld overlays is Alloy 52M, which has been demonstrated to be resistant to PWSCC [10].

0800692.404, Rev. 1 1-1 Structural Integrity Associates, Inc.

1.0 INTRODUCTION

1.1 Background

Southern California Edison (SCE) is applying full structural weld overlays (FSWOLs) on dissimilar metal butt welds (DMWs) of the hot leg components listed below at the San Onofre Nuclear Generating Station (SONGS), Units 2 and 3, to eliminate dependence upon the Alloy 821182 welds as pressure boundary welds, and to mitigate any potential primary water stress corrosion cracking (PWSCC) in these welds in the future.

This report summarizes the structural evaluations of preemptive, full structural weld overlay designs for one Hot Leg Surge Nozzle, one Hot Leg Shutdown Cooling Nozzle and one Hot Leg Drain Nozzle for each unit.

Revision 1 of this Design Report removes all references to "Proprietary Information." No content changes were made.

1.2 Weld Overlay Repairs Weld overlays have been used routinely in U.S. BWRs and PWRs to repair flaws associated with stress corrosion cracking. The process is an ASME Code approved repair method under the Relief Requests [2], which are based on ASME Code Case N-504-2 and N-638-1 [1]. As an alternative to post weld heat treatment (PWHT) of the nozzle material, the overlays are applied with the ambient temperature temperbead welding technique, using Gas Tungsten Arc Welding (GT A W) with selective and carefully controlled weld bead placement and heat input, in accordance with the Relief Requests [2], which are based on ASME Code Case N-504-2 and N-638-1 [1]. Nickel alloy weld filler metal is utilized for the weld overlays for material compatibility with the underlying pipe, safe end, and nozzle materials. The specified welding material for the weld overlays is Alloy 52M, which has been demonstrated to be resistant to PWSCC [10].

0800692.404, Rev. 1 1-1

!i) Strueturallntegrity Associates, Inc.

1.3 Objectives and Report Organization The objectives of this report are to provide the technical basis and a summary of the weld overlay design and analysis results for the San Onofre Nuclear Generating Station (SONGS),

Units 2 and 3 Hot Leg Surge, Hot Leg Shutdown Cooling and Hot Leg Drain Nozzle overlays described in Section 1.1. Section 2.0 of this report discusses the repair and evaluation criteria for weld overlay designs plus the basic structural sizing of the overlays. Section 3.0 summarizes the residual stress analyses performed. Section 4.0 discusses the evaluation of weld overlay effects on the piping systems. Consideration of flaw growth into the overlay repair is discussed in Section 5.0. Analyses that supplement the existing piping, safe end, and nozzle Stress Reports and demonstrate that the overlaid components meet ASME Code,Section III requirements are described in Section 6.0. Section 7.0 contains a reconciliation of the original Code-of-Record with a later edition of the ASME Code used in the evaluations herein. Section 8.0 contains an evaluation of the as-built conditions. A summary and conclusions are provided in Section 9.0, while Section 10.0 provides references used in this report. Detailed calculations and design drawings supporting this report are listed in Section 11.0 and are contained in Appendices A through JJ (provided in separate individual calculation packages and drawings and transmitted separately from this report).

0800692.404, Rev. 1 1-2 Structural Integrity Associates, Inc.

1.3 Objectives and Report Organization The objectives of this report are to provide the technical basis and a summary of the weld overlay design and analysis results for the San Onofre Nuclear Generating Station (SONGS),

Units 2 and 3 Hot Leg Surge, Hot Leg Shutdown Cooling and Hot Leg Drain Nozzle overlays described in Section 1.1. Section 2.0 of this report discusses the repair and evaluation criteria for weld overlay designs plus the basic structural sizing of the overlays. Section 3.0 summarizes the residual stress analyses performed. Section 4.0 discusses the evaluation of weld overlay effects on the piping systems. Consideration of flaw growth into the overlay repair is discussed in Section 5.0. Analyses that supplement the existing piping, safe end, and nozzle Stress Reports and demonstrate that the overlaid components meet ASME Code,Section III requirements are described in Section 6.0. Section 7.0 contains a reconciliation of the original Code-of-Record with a later edition of the ASME Code used in the evaluations herein. Section 8.0 contains an evaluation of the as-built conditions. A summary and conclusions are provided in Section 9.0, while Section 10.0 provides references used in this report. Detailed calculations and design drawings supporting this report are listed in Section 11.0 and are contained in Appendices A through JJ (provided in separate individual calculation packages and drawings and transmitted separately from this report).

0800692.404, Rev. 1 1-2

!l) Structural Integrity Associates, Inc.

2.0 WELD OVERLAY DESIGN 2.1 Weld Overlay Application The weld overlay repairs are carefully controlled using the following steps in order to assure the integrity of the overlays and underlying weldments:

1.

Surface preparation by grinding of the existing weld crown and any local protrusions to blend smoothly into the base metal, plus the removal of oxides and other foreign materials from the area to be overlaid.

2.

Layout of the weld overlay per the design drawing by appropriately punch marking the pipe and nozzle.

3.

Liquid penetrant examination of the surface to be overlaid to assure the surface is found acceptable. Special requirements apply to subsequent overlay layers if this requirement is not met.

4.

Measurement of the diameter on each side of the weld to be overlaid using physical measurements.

5.

Application of the ambient temperature temperbead weld overlay layers.

6.

Application of the remainder of the weld overlay layers to achieve a full structural weld overlay.

7.

Surface preparation of the completed weld overlay to assure adequate surface contour and smoothness for UT examination.

8.

Measurement of the final overlay thicknesses and lengths by physical measurements.

9.

Measurement of axial shrinkage between punch marks placed on the nozzle and pipe.

10.

Liquid penetrant examination of the final overlay surface.

11.

Volumetric examination of the completed weld overlay repair plus the outer portion of the original wall thickness using UT procedures and personnel qualified in accordance with ASME Code,Section XI, Appendix VIII, as implemented through the EPRI Performance Demonstration Initiative (PDI).

0800692.404, Rev. 1 2-1 V

Structural Integrity Associates, Inc.

2.0 WELD OVERLAY DESIGN 2.1 Weld Overlay Application The weld overlay repairs are carefully controlled using the following steps in order to assure the integrity of the overlays and underlying weldments:

1.

Surface preparation by grinding of the existing weld crown and any local protrusions to blend smoothly into the base metal, plus the removal of oxides and other foreign materials from the area to be overlaid.

2.

Layout of the weld overlay per the design drawing by appropriately punch marking the pipe and nozzle.

3.

Liquid penetrant examination of the surface to be overlaid to assure the surface is found acceptable. Special requirements apply to subsequent overlay layers if this requirement is not met.

4.

Measurement of the diameter on each side of the weld to be overlaid using physical measurements.

5.

Application of the ambient temperature temperbead weld overlay layers.

6.

Application of the remainder of the weld overlay layers to achieve a full structural weld overlay.

7.

Surface preparation of the completed weld overlay to assure adequate surface contour and smoothness for UT examination.

8.

Measurement of the final overlay thicknesses and lengths by physical measurements.

9.

Measurement of axial shrinkage between punch marks placed on the nozzle and pipe.

10.

Liquid penetrant examination of the final overlay surface.

11.

Volumetric examination of the completed weld overlay repair plus the outer portion of the original wall thickness using UT procedures and personnel qualified in accordance with ASME Code,Section XI, Appendix VIII, as implemented through the EPRI Performance Demonstration Initiative (PDI).

0800692.404, Rev. 1 2-1 l) Structural Integrity Associates, Inc.

2.2 Criteria for Design of Full Structural Weld Overlay Repairs The requirements for design of weld overlay repairs are defined in the Relief Requests [2], which are based on ASME Code Case N-504-2 and N-638-1 [1]. The analytical bases for the design of the repairs are in accordance with the requirements of ASME Code,Section XI, IWB-3641 [3].

Weld overlay repairs are considered to be acceptable long-term repairs for PWSCC-flawed weldments if they meet a conservative set of design assumptions which qualify them as "full structural" weld overlays. The three principal design requirements that qualify a weld overlay as "full structural" are:

1. The design basis for the repair is a circumferentially oriented flaw that extends 3600 around the component, and is through the original component wall. This conservative assumption eliminates concerns about PWSCC susceptibility of the original Alloy 82/182 dissimilar metal weld (DMW). In addition, potential concerns about the integrity of the original butt weld material are not applicable, since no credit is taken in the design process for the load carrying capability of this weld.
2. As required by ASME Code,Section XI, IWB-3641 [3], a combination of internal pressure, deadweight, seismic, and other dynamic stresses is used in the design of weld overlay repairs.

Thermal and other secondary stresses are not required to be included for structural sizing calculations (since the repairs are applied using a GTAW process that produces a high toughness weld deposit), but they are addressed later in subsequent stress, fatigue, and stress corrosion cracking evaluations.

3. Following the repair, the surface finish of the overlay must be sufficiently smooth to allow preservice and future inservice ultrasonic examinations through the overlay material and into a portion of the original base metal. The purpose of these examinations is to demonstrate that the overlay design basis does not degrade with time due to flaw propagation.

0800692.404, Rev. 1 2-2 V

Structural Integrity Associates, Inc.

2.2 Criteria for Design of Full Structural Weld Overlay Repairs The requirements for design of weld overlay repairs are defined in the Relief Requests [2], which are based on ASME Code Case N-504-2 and N-638-1 [1]. The analytical bases for the design of the repairs are in accordance with the requirements of ASME Code,Section XI, IWB-3641 [3].

Weld overlay repairs are considered to be acceptable long-term repairs for PWSCC-flawed weldments if they meet a conservative set of design assumptions which qualify them as "full structural" weld overlays. The three principal design requirements that qualify a weld overlay as "full structural" are:

1. The design basis for the repair is a circumferentially oriented flaw that extends 3600 around the component, and is through the original component wall. This conservative assumption eliminates concerns about PWSCC susceptibility of the original Alloy 82/182 dissimilar metal weld (DMW). In addition, potential concerns about the integrity of the original butt weld material are not applicable, since no credit is taken in the design process for the load carrying capability of this weld.
2. As required by ASME Code,Section XI, IWB-3641 [3], a combination of internal pressure, deadweight, seismic, and other dynamic stresses is used in the design of weld overlay repairs.

Thermal and other secondary stresses are not required to be included for structural sizing calculations (since the repairs are applied using a GTA W process that produces a high toughness weld deposit), but they are addressed later in subsequent stress, fatigue, and stress corrosion cracking evaluations.

3. Following the repair, the surface finish of the overlay must be sufficiently smooth to allow preservice and future inservice ultrasonic examinations through the overlay material and into a portion of the original base metal. The purpose of these examinations is to demonstrate that the overlay design basis does not degrade with time due to flaw propagation.

0800692.404, Rev. 1 2-2 t! Structural Integrity Associates, Inc.

2.3 Weld Overlay Structural Sizing 2.3.1 Weld Overlay Thickness Design drawings for the Hot Leg Shutdown Cooling Nozzle, the Hot Leg Surge Nozzle and the Hot Leg Drain Nozzle are provided by SI and are identified in Appendices HH, II and JJ, respectively. It is noted that the Hot Leg Surge design drawing, Appendix II, contains two different configurations, e.g. a Unit 2 and a Unit 3 configuration. The difference is that the Unit 3 plant configuration required that a third weld, the pup piece to elbow weld, also be overlaid. Final construction drawings of the overlays, provided by Welding Services Inc., are contained in [15-20]. Sizing calculations for the weld overlays are discussed as follows.

Detailed sizing calculations for weld overlay thickness are documented in Appendix D (SI Calculation 0800692.310) for the Hot Leg Shutdown Cooling Nozzle, Appendix L (SI Calculation 0800692.320) for the Hot Leg Surge Nozzle and Appendix U (SI Calculation 0800692.330) for the Hot Leg Drain Nozzle. For all the above nozzles, the "Codes and Standards" module of the pc-CRACK computer program [4], which incorporates ASME Code,Section XI, IWB-3640 evaluation methodology, was used to determine the thickness of the overlays using loads and stress combinations provided by SCE. Normal operating/upset (Service Level A/B) and emergency/faulted (Service Level C/D) load combinations were considered in this evaluation, and the design was based on the more limiting results. The resulting minimum required overlay thicknesses are summarized in Table 2-1.

As stated in Section 1.2, preemptive weld overlays will be installed using Alloy 52M filler metal.

However, Alloy 52M weld metal has demonstrated sensitivity to certain impurities, such as sulfur, when deposited onto austenitic stainless steel base materials. Therefore, a butter (transitional) layer of austenitic stainless steel filler metal will be applied across the austenitic stainless steel base material. The austenitic stainless steel butter layer will not be included in the structural weld overlay thicknesses defined above.

0800692.404, Rev. 1 2-3 Structural Integrity Associates, Inc.

2.3 Weld Overlay Structural Sizing 2.3.1 Weld Overlay Thickness Design drawings for the Hot Leg Shutdown Cooling Nozzle, the Hot Leg Surge Nozzle and the Hot Leg Drain Nozzle are provided by SI and are identified in Appendices HH, II and JJ, respectively. It is noted that the Hot Leg Surge design drawing, Appendix II, contains two different configurations, e.g. a Unit 2 and a Unit 3 configuration. The difference is that the Unit 3 plant configuration required that a third weld, the pup piece to elbow weld, also be overlaid. Final construction drawings of the overlays, provided by Welding Services Inc., are contained in [15-20]. Sizing calculations for the weld overlays are discussed as follows.

Detailed sizing calculations for weld overlay thickness are documented in Appendix D (SI Calculation 0800692.310) for the Hot Leg Shutdown Cooling Nozzle, Appendix L (SI Calculation 0800692.320) for the Hot Leg Surge Nozzle and Appendix U (SI Calculation 0800692.330) for the Hot Leg Drain Nozzle. For all the above nozzles, the "Codes and Standards" module of the pc-CRACK computer program [4], which incorporates ASME Code,Section XI, IWB-3640 evaluation methodology, was used to determine the thickness of the overlays using loads and stress combinations provided by SCE. Normal operating/upset (Service Level AlB) and emergency/faulted (Service Level C/D) load combinations were considered in this evaluation, and the design was based on the more limiting results. The resulting minimum required overlay thicknesses are summarized in Table 2-1.

As stated in Section 1.2, preemptive weld overlays will be installed using Alloy 52M filler metal.

However, Alloy 52M weld metal has demonstrated sensitivity to certain impurities, such as sulfur, when deposited onto austenitic stainless steel base materials. Therefore, a butter (transitional) layer of austenitic stainless steel filler metal will be applied across the austenitic stainless steel base material. The austenitic stainless steel butter layer will not be included in the structural weld overlay thicknesses defined above.

0800692.404, Rev. 1 2-3

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Structurallntegrily Associates, Inc.

2.3.2 Weld Overlay Length Appendices D, L, and U, discussed in Section 2.3.1, also present detailed calculations for minimum weld overlay (WOL) lengths. The minimum length requirements are summarized in Table 2-1. Note that these length dimensions are measured from the intersection of the original Alloy 82/182 construction welds (or stainless steel weld, if appropriate) with the safe end/piping or nozzle material on the outside surface of the nozzle.

WOL access for preservice examination requires that the overlay length and profile be such that the required post-WOL examination volume can be inspected using PDI qualified non-destructive examination (NDE) techniques. This requirement could cause the overlay length to be longer than required for structural reinforcement. The WOL designs have been reviewed by qualified NDE personnel to ensure that they meet this requirement.

2.4 Comparison with Field Measurements The minimum measured as-built thicknesses and lengths of the overlays, after final surface contouring [15-20], are summarized in Tables 2-2 for Unit 2 and Table 2-3 for Unit 3. These measurements exceed the minimum required structural design dimensions shown in Table 2-1, thereby demonstrating the adequacy of the as-installed repairs. The as-built evaluation of these overlay dimensions is addressed in Section 8.0 of this report.

0800692.404, Rev. 1 2-4 Structural Integrity Associates, Inc.

2.3.2 Weld Overlay Length Appendices D, L, and U, discussed in Section 2.3.1, also present detailed calculations for minimum weld overlay (WOL) lengths. The minimum length requirements are summarized in Table 2-1. Note that these length dimensions are measured from the intersection of the original Alloy 821182 construction welds (or stainless steel weld, if appropriate) with the safe end/piping or nozzle material on the outside surface of the nozzle.

WOL access for preservice examination requires that the overlay length and profile be such that the required post-WOL examination volume can be inspected using PDr qualified non-destructive examination (NDE) techniques. This requirement could cause the overlay length to be longer than required for structural reinforcement. The WOL designs have been reviewed by qualified NDE personnel to ensure that they meet this requirement.

2.4 Comparison with Field Measurements The minimum measured as-built thicknesses and lengths of the overlays, after final surface contouring [15-20], are summarized in Tables 2-2 for Unit 2 and Table 2-3 for Unit 3. These measurements exceed the minimum required structural design dimensions shown in Table 2-1, thereby demonstrating the adequacy of the as-installed repairs. The as-built evaluation of these overlay dimensions is addressed in Section 8.0 of this report.

0800692.404, Rev. 1 2-4 lJ Structural Integrity Associates, Inc.

Table 2-1: Weld Overlay Minimum Structural Thickness and Length Requirements-Unit 2 and Unit 3 16" Hot Leg 12" Hot Leg 12" Hot Leg 2" Hot Leg Shutdown Item Location Cooling Surge Surge Drain Nole Nozzle-Unit 2 Nozzle-Unit 3 Nozzle Nozzle Nozzle 0.563 0.573 0.573 0.364 Side Minimum Safe End 0.531/0.472 0.5413/0.5287 0.541/0.514 0.248/0.196 Side**

Thickness Pipe-Pup (in.)

Piece NA NA 0.514***/0.538***

NA Side***

Pipe Side 0.531 0.5287 0.538 0.231 Nozzle 1.420 1.594 1.596 0.639 Side Minimum*

Safe Length Side NA NA NA NA (in.)

Pipe Pipe 1.505 1.804 1.844 1.339 Side

  • Length shown is the minimum required for structural acceptance and does not include additional length necessary to meet inspectability.
    • First number is for the safe end side of the nozzle-to-safe end weld, and the second number is for the safe end side of the safe end-to-elbow/pup piece weld.
      • First number is for the pup piece side, the second number is for the elbow/pipe side of the weld.

Unit 3 contains a pup piece and an additional weld between the safe end and the pipe.

0800692.404, Rev. 1 2-5 Structural Integrity Associates, Inc.

Table 2-1: Weld Overlay Minimum Structural Thickness and Length Requirements-Unit 2 and Unit 3 Item Minimum Thickness (in.)

Minimum*

Length (in.)

16" Hot Leg 12" Hot Leg 12" Hot Leg 2" Hot Leg Shutdown Location Cooling Surge Surge Drain Nozzle Nozzle-Unit 2 Nozzle-Unit 3 Nozzle Nozzle 0.563 0.573 0.573 0.364 Side Safe End 0.53110.472 0.5413/0.5287 0.54110.514 0.248/0.196 Side**

Pipe-Pup Piece NA NA 0.514***/0.538***

NA Side***

Pipe Side 0.531 0.5287 0.538 0.231 Nozzle 1.420 1.594 1.596 0.639 Side Safe End Side NA NA NA NA Pipe Side 1.505 1.804 1.844 1.339

  • Length shown is the minimum required for structural acceptance and does not include additional length necessary to meet inspectability.
    • First number is for the safe end side of the nozzle-to-safe end weld, and the second number is for the safe end side of the safe end-to-elbow/pup piece weld.
      • First number is for the pup piece side, the second number is for the elbow/pipe side of the weld.

Unit 3 contains a pup piece and an additional weld between the safe end and the pipe.

0800692.404, Rev. 1 2-5

~

Structural Integrity Associates, Inc.

Table 2-2: Post-Weld Overlay Minimum As-Built Dimensions-Unit 2 16" Hot Leg 12" Hot Leg 2" Hot Leg Item Location Shutdown Surge Drain Cooling Nozzle Nozzle Nozzle Nozzle Side 0.88 0.81 0.40 Minimum Safe End Thickness Side*

0..88**/0.89**

0.81"*/0.62"*

0.40"*/0.43*

(in.)

Pipe 0.89 0.62 0.43 Side Nozzle Side 3.76 4.11 1.17 Minimum***

Safe End Length Side NA NA NA (in.)

Pipe 3.37 3.59 2.39 Side

  • First number is for the safe end side of the nozzle-to-safe end weld, and the second number is for the safe end side of the safe end-to-pipe weld
    • Conservatively assumed equal to thickness on the nozzle or pipe side, respectively.
      • Length shown is the minimum of four azimuthal examinations.

0800692.404, Rev. 1 2-6 Structural Integrity Associates, Inc.

Table 2-2: Post-Weld Overlay Minimum As-Built Dimensions-Unit 2 16" Hot Leg 12" Hot Leg 2" Hot Leg Shutdown Item Location Cooling Surge Drain Nozzle Nozzle Nozzle Nozzle Side 0.88 0.81 0.40 Minimum Safe End Thickness Side*

0.. 88**/0.89**

0.81**10.62**

0.40**10.43**

(in.)

Pipe Side 0.89 0.62 0.43 Nozzle Side 3.76 4.11 1.17 Minimum***

Safe End Length Side NA NA NA (in.)

Pipe Side 3.37 3.59 2.39

  • First number is for the safe end side of the nozzle-to-safe end weld, and the second number is for the safe end side of the safe end-to-pipe weld
    • Conservatively assumed equal to thickness on the nozzle or pipe side, respectively.
      • Length shown is the minimum of four azimuthal examinations.

0800692.404, Rev. 1 2-6 lJ Structural Integrity Associates, Inc.

Table 2-3: Post-Weld Overlay Minimum As-Built Dimensions-Unit 3 16" Hot Leg 12" Hot Leg 2" Hot Leg Item Location Shutdown Surge Drain Cooling Nozzle Nozzle Nozzle Nozzle Side 0.85 0.59 0.38 Safe End 0.85**/0.89**

0.48 Minimum Side*

Thickness Pipe-Pup (in.)

Piece NA NA Side Pipe 0.89 0.85 0.46 Side Nozzle Side 3.64 3.65 1.63 Minimum***

Safe End Length Side NA NA NA (in.)

Pipe 3.48 2.81 2.40

_Side

  • First number is for the safe end side of the nozzle-to-safe end weld, and the second number is for the safe end side of the safe end-to-pipe weld
    • Conservatively assumed equal to thickness on the nozzle or pipe side, respectively.
      • Length shown is the minimum of four azimuthal examinations.
        • Minimum thickness is met by inspection of the As-Built Drawing [ 16].

0800692.404, Rev. 1 2-7 Structural Integrity Associates, Inc.

Table 2-3: Post-Weld Overlay Minimum As-Built Dimensions-Unit 3 16" Hot Leg 12" Hot Leg 2" Hot Leg Shutdown Item Location Cooling Surge Drain Nozzle Nozzle Nozzle Nozzle Side 0.85 0.59 0.38 Safe End 0.85**10.89**

0.48 Minimum Side*

Thickness Pipe-Pup (in.)

Piece NA NA Side Pipe 0.89 0.85 0.46 Side Nozzle Side 3.64 3.65 1.63 Minimum***

Safe End Length Side NA NA NA (in.)

Pipe Side 3.48 2.81 2.40

  • First number is for the safe end side of the nozzle-to-safe end weld, and the second number is for the safe end side of the safe end-to-pipe weld
    • Conservatively assumed equal to thickness on the nozzle or pipe side, respectively.
      • Length shown is the minimum of four azimuthal examinations.
        • Minimum thickness is met by inspection of the As-Built Drawing [16].

0800692.404, Rev. 1 2-7 e Structural Integrity Associates, Inc.

3.0 RESIDUAL STRESS ANALYSES

3.1 Background

In addition to providing structural reinforcement to the flawed location to meet ASME Code safety margins, the weld overlay produces beneficial residual stresses that support the mitigation of PWSCC. The weld overlay approach has been used in the U.S. nuclear industry on hundreds of welds. There have been no reports of crack extension after application of the weld overlay.

Thus, the compressive stresses caused by the weld overlay have been effective in mitigating crack growth. In addition, the weld residual stresses act as compressive mean stresses in the fatigue crack growth assessments.

The weld residual stresses for the weld overlays were determined by detailed elastic-plastic finite element analyses as discussed in Section 3.2. The residual stress calculations were based on the minimum drawing dimensions, which include inspectability considerations. The analysis approach has been previously documented to provide predictions of weld residual stresses that are in reasonable agreement with experimental measurements [5, 6, 7, and 8].

3.2 Technical Approach The residual stresses due to welding are controlled by the welding parameters: thermal transients due to application of the welding process, thermal boundary conditions, temperature-dependent material properties, elastic-plastic stress reversals, and air or water backing during weld deposition. The analytical technique uses finite element analysis to simulate the multi-pass weld process. In order to reduce computational time, individual weld bead passes are lumped into larger nuggets.

To obtain a bounding assessment of the impact of the weld overlay on the DMW, the residual stress assessment must consider residual stresses that existed prior to application of the overlay.

Thus, the weld overlay analysis utilized a conservative bounding assumption regarding residual stresses that may be present due to assumed weld repairs that may have occurred during plant construction.

0800692,404, Rev. 1 3-1 V

Structural Integrity Associates, Inc.

3.0 RESIDUAL STRESS ANALYSES

3.1 Background

In addition to providing structural reinforcement to the flawed location to meet ASME Code safety margins, the weld overlay produces beneficial residual stresses that support the mitigation ofPWSCC. The weld overlay approach has been used in the U.S. nuclear industry on hundreds of welds. There have been no reports of crack extension after application of the weld overlay.

Thus, the compressive stresses caused by the weld overlay have been effective in mitigating crack growth. In addition, the weld residual stresses act as compressive mean stresses in the fatigue crack growth assessments.

The weld residual stresses for the weld overlays were determined by detailed elastic-plastic finite element analyses as discussed in Section 3.2. The residual stress calculations were based on the minimum drawing dimensions, which include inspectability considerations. The analysis approach has been previously documented to provide predictions of weld residual stresses that are in reasonable agreement with experimental measurements [5,6, 7, and 8].

3.2 Technical Approach The residual stresses due to welding are controlled by the welding parameters: thermal transients due to application of the welding process, thermal boundary conditions, temperature-dependent material properties, elastic-plastic stress reversals, and air or water backing during weld deposition. The analytical technique uses finite element analysis to simulate the multi-pass weld process. In order to reduce computational time, individual weld bead passes are lumped into larger nuggets.

To obtain a bounding assessment of the impact of the weld overlay on the DMW, the residual stress assessment must consider residual stresses that existed prior to application of the overlay.

Thus, the weld overlay analysis utilized a conservative bounding assumption regarding residual stresses that may be present due to assumed weld repairs that may have occurred during plant construction.

0800692.404, Rev. 1 3-1 lJ Structural Integrity Associates, Inc.

Two-dimensional, axisymmetric finite element models were developed for each of the nozzles using the ANSYS software package [9]. Modeling of the weld nuggets in the overlay is illustrated in Figure 3-1 for the 16" Hot Leg Shutdown Cooling Nozzle, Figure 3-2 for the 12" Hot Leg Surge Nozzle for Unit 2, Figure 3-3 for the 12" Hot Leg Surge Nozzle for Unit 3 and Figure 3-4 for the 2" Hot Leg Drain Nozzle. Note that the models include a simulated inside surface (ID) repair at the DMW location with a depth of approximately 50% of the original wall thickness for the full circumferential extent. This assumption is considered to conservatively bound any weld repairs that may have been performed during plant construction, from the standpoint of producing tensile residual stresses at the ID of the DMW.

An analysis is performed to simulate the welding process of the ID weld repair at the DMW location, the Alloy 82/182 or stainless steel safe end-to-pipe weld, the overlay welding process, and finally, a slow heatup to operating conditions of temperature and pressure. The analysis consists of a thermal pass to determine the temperature response of the model to each individual lumped weld nugget as it is added in sequence, followed by a non-linear elastic-plastic stress pass to calculate the residual stress due to the temperature cycling from the application of each lumped weld pass. Since residual stress is a function of the welding history, the stress pass for each nugget is applied to the residual stress field induced from all previously applied weld nuggets.

After completion of the weld overlay simulation, the model was allowed to cool to a uniform steady state temperature of 70'F, and then brought up to normal operating conditions of temperature and pressure to obtain the residual stresses.

Residual stress finite element model development is discussed in detail in Appendix F (SI Calculation 0800692.312) for the 16" Hot Leg Shutdown Cooling Nozzle, Appendix N (SI Calculation 0800692.322) for the 12" Hot Leg Surge Nozzle for Unit 2, Appendix W (SI Calculation 0800692.332) for the 2" Hot Leg Drain Nozzle, and Appendix CC (SI Calculation 0800692.342) for the 12" Hot Leg Surge Nozzle for Unit 3.

Details of the residual stress analyses are discussed in Appendix H (SI Calculation 0800692.314) for the 16" Hot Leg Shutdown Cooling Nozzle, Appendix P (SI Calculation 0800692.324) for 0800692.404, Rev. 1 3-2 V

Structural Integrity Associates, Inc.

Two-dimensional, axisymmetric finite element models were developed for each of the nozzles using the ANSYS software package [9]. Modeling of the weld nuggets in the overlay is illustrated in Figure 3-1 for the 16" Hot Leg Shutdown Cooling Nozzle, Figure 3-2 for the 12" Hot Leg Surge Nozzle for Unit 2, Figure 3-3 for the 12" Hot Leg Surge Nozzle for Unit 3 and Figure 3-4 for the 2" Hot Leg Drain Nozzle. Note that the models include a simulated inside surface (ID) repair at the DMW location with a depth of approximately 50% of the original wall thickness for the full circumferential extent. This assumption is considered to conservatively bound any weld repairs that may have been perfonned during plant construction, from the standpoint of producing tensile residual stresses at the ID of the DMW.

An analysis is perfonned to simulate the welding process of the ID weld repair at the DMW location, the Alloy 82/182 or stainless steel safe end-to-pipe weld, the overlay welding process, and finally, a slow heatup to operating conditions of temperature and pressure. The analysis consists of a thennal pass to detennine the temperature response of the model to each individual lumped weld nugget as it is added in sequence, followed by a non-linear elastic-plastic stress pass to calculate the residual stress due to the temperature cycling from the application of each lumped weld pass. Since residual stress is a function of the welding history, the stress pass for each nugget is applied to the residual stress field induced from all previously applied weld nuggets.

After completion of the weld overlay simulation, the model was allowed to cool to a unifonn steady state temperature of 70°F, and then brought up to nonnal operating conditions of temperature and pressure to obtain the residual stresses.

Residual stress finite element model development is discussed in detail in Appendix F (SI Calculation 0800692.312) for the 16" Hot Leg Shutdown Cooling Nozzle, Appendix N (SI Calculation 0800692.322) for the 12" Hot Leg Surge Nozzle for Unit 2, Appendix W (SI Calculation 0800692.332) for the 2" Hot Leg Drain Nozzle, and Appendix CC (SI Calculation 0800692.342) for the 12" Hot Leg Surge Nozzle for Unit 3.

Details of the residual stress analyses are discussed in Appendix H (SI Calculation 0800692.314) for the 16" Hot Leg Shutdown Cooling Nozzle, Appendix P (SI Calculation 0800692.324) for 0800692.404, Rev. 1 3-2

~

Structural Integrity Associates, Inc.

the 12" Hot Leg Surge Nozzle for Unit 2, Appendix EE (SI Calculation 0800692.344) for the 12" Hot Leg Surge Nozzle for Unit 3 and Appendix Y (SI Calculation 0800692.334) for the 2" Hot Leg Drain Nozzle. Material properties used in the analyses are reported in Appendix A (SI Calculation 0800692.301) 3.3 Residual Stress Analysis Results The pre-weld overlay residual stress distribution, including the effect of the assumed 360 degree construction weld repair, is shown in Figure 3-5 for the 12" Hot Leg Surge Nozzle for Unit 2.

Note the highly tensile stress state on the inside surface of the DMW. This result represents a conservative starting point for the weld overlay residual stress analysis, and is consistent with

'field experience with PWSCC in PWR dissimilar metal welds (i.e., essentially all welds in which PWSCC has occurred were found to have had significant weld repairs during plant construction).

The post-weld overlay residual stresses at room temperature as well as at operating temperature and pressure, representing the final stage of the analysis, are presented in Figures 3-6 and 3-7, respectively, for the 12" Hot Leg Surge Nozzle for Unit 2. It is seen from these figures that, after application of the WOL, the stresses on the inside surface of the original DMW are compressive.

The ID compression is balanced by tensile stresses in the WOL. Tensile residual stresses in the WOL are not a PWSCC concern, because the overlays were installed with Alloy 52M weld metal, a material that has been shown to offer significant improvement in PWSCC resistance

[10].

The favorable residual stress reversal on the susceptible ID surface is further illustrated in Figures 3-8 and 3-9, which are plots of ID surface stresses, before and after application of the WOL, for the Hot Leg Surge Nozzle for Unit 2. The compressive nature of the ID surface stresses, as opposed to the high tensile pre-overlay values, is demonstration that the overlays will serve their intended purpose of preventing any new PWSCC initiation in regions of the welds that are not cracked, and inhibiting growth of any existing cracks that may have initiated.

Through-wall residual stress distributions from these analyses are used later as input to fatigue crack growth calculations and PWSCC evaluations. Similar results are obtained for the other nozzles evaluated herein.

0800692.404, Rev. 1 3-3 Structural Integrity Associates, Inc.

the 12" Hot Leg Surge Nozzle for Unit 2, Appendix EE (SI Calculation 0800692.344) for the 12" Hot Leg Surge Nozzle for Unit 3 and Appendix Y (SI Calculation 0800692.334) for the 2" Hot Leg Drain Nozzle. Material properties used in the analyses are reported in Appendix A (SI Calculation 0800692.301) 3.3 Residual Stress Analysis Results The pre-weld overlay residual stress distribution, including the effect of the assumed 360 degree construction weld repair, is shown in Figure 3-5 for the 12" Hot Leg Surge Nozzle for Unit 2.

Note the highly tensile stress state on the inside surface of the DMW. This result represents a conservative starting point for the weld overlay residual stress analysis, and is consistent with

'field experience with PWSCC in PWR dissimilar metal welds (i.e., essentially all welds in which PWSCC has occurred were found to have had significant weld repairs during plant construction).

The post-weld overlay residual stresses at room temperature as well as at operating temperature and pressure, representing the final stage of the analysis, are presented in Figures 3-6 and 3-7, respectively, for the 12" Hot Leg Surge Nozzle for Unit 2. It is seen from these figures that, after application of the WOL, the stresses on the inside surface of the original DMW are compressive.

The 1D compression is balanced by tensile stresses in the WOL. Tensile residual stresses in the WOL are not a PWSCC concern, because the overlays were installed with Alloy 52M weld metal, a material that has been shown to offer significant improvement in PWSCC resistance

[10].

The favorable residual stress reversal on the susceptible 1D surface is further illustrated in Figures 3-8 and 3-9, which are plots ofID surface stresses, before and after application of the WOL, for the Hot Leg Surge Nozzle for Unit 2. The compressive nature of the 1D surface stresses, as opposed to the high tensile pre-overlay values, is demonstration that the overlays will serve their intended purpose of preventing any new PWSCC initiation in regions of the welds that are not cracked, and inhibiting growth of any existing cracks that may have initiated.

Through-wall residual stress distributions from these analyses are used later as input to fatigue crack growth calculations and PWSCC evaluations. Similar results are obtained for the other nozzles evaluated herein.

0800692.404, Rev. 1 3-3

!l) Structural Integrity Associates, Inc.

Detailed descriptions of the residual stress analyses, including complete presentation of the input, assumptions and results, are contained in Appendix H (SI Calculation 0800692.314) for the 16" Hot Leg Shutdown Cooling Nozzle, Appendix P (SI Calculation 0800692.324) for the 12" Hot Leg Surge Nozzle for Unit 2, Appendix Y (SI Calculation 0800692.334) for the 2" Hot Leg Drain Nozzle and Appendix EE (SI Calculation 0800692.344) for the 12" Hot Leg Surge Nozzle for Unit 3.

Structural Integrity Associates, Inc.

Detailed descriptions of the residual stress analyses, including complete presentation of the input, assumptions and results, are contained in Appendix H (SI Calculation 0800692.314) for the 16" Hot Leg Shutdown Cooling Nozzle, Appendix P (SI Calculation 0800692.324) for the 12" Hot Leg Surge Nozzle for Unit 2, Appendix Y (SI Calculation 0800692.334) for the 2" Hot Leg Drain Nozzle and Appendix EE (SI Calculation 0800692.344) for the 12" Hot Leg Surge Nozzle for Unit 3.

0800692.404, Rev. 1 3-4 lJ Structural Integrity Associates, Inc.

FT_ 2-=r Figure 3-1: Lumped Weld Nuggets for 16" Hot Leg Shutdown Cooling Nozzle Residual Stress Analysis 0800692.404, Rev. 1 3-5 V

Structural Integrity Associates, Inc.

Figure 3-1: Lumped Weld Nuggets for 16" Hot Leg Shutdown Cooling Nozzle Residual Stress Analysis 0800692.404, Rev. 1 3-5 l) Structural Integrity Associates, Inc.

1 AN ELEMENTS MAT NUM x

SONGS SURGE Nozzle MIN Overlay -

Residual Stresses Figure 3-2: Lumped Weld Nuggets for 12" Hot Leg Surge Nozzle Residual Stress Analysis, Unit 2 0800692.404, Rev. 1 3-6 V

Structural Integrity Associates, Inc.

1 ELEMENTS MAT NUM x

L SONGS SURGE Nozz l e MIN Overlay -

Residual St r esses Figure 3-2: Lumped Weld Nuggets for 12" Hot Leg Surge Nozzle Residual Stress Analysis, Unit 2 0800692.404, Rev. 1 3-6 lJ Structural Integrity Associates, Inc.

Figure 3-3: Lumped Weld Nuggets for 12" Hot Leg Surge Nozzle Residual Stress Analysis, Unit 3 V

Structural Integrity Associates, Inc.

0800692.404, Rev. 1 3-7 Layer I: (Alloy Layer 8: (A lloy 52M)

Layer 7: (A lloy 52M)

Layer 6: (Alloy 52M) 5: (Alloy 52M) 4: (Alloy 52M)

Layer 3: (Alloy 52M)

Layer 2: (Alloy 52M) 10 8

6

."'--Lu.)cr4 I: (ERJ08L)

Figure 3-3: Lumped Weld Nuggets for 12" Hot Leg Surge Nozzle Residual Stress Analysis, Unit 3 0800692.404, Rev. 1 3-7

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Structural Integrity Associates, Inc.

IEEAN ELEMENTS x

IZ SONGS Drain Nozzle Overlay SONGS Drain Nozzle Overlay Figure 3-4: Lumped Weld Nuggets for 2" Hot Leg Drain Nozzle Residual Stress Analysis

)0692.404, Rev. 1 3-8 V

Structural Integrity Associates, Inc.

08(

ELEMENTS x

L SONGS Drain Nozzle Overlay Figure 3-4: Lumped Weld Nuggets for 2" Hot Leg Drain Nozzle Residual Stress Analysis 0800692.404, Rev. 1 3-8 l) Structural Integrity Associates, Inc.

AN NODAL SOLUTION STEP=79 SUB =1 TIME=69 SY (AVG)

RSYS=0 DMX =.043355 SMN -- 47894 SMX =63278 X11

-4789

-23189

-35542 Residual stress analysis i151 10837 26221 38573 nu o Z -

63278 Axial Stress AN NODAL SOLUTION STEP=79 SUB =1 TIME=69 SZ (AVG)

RSYS=0 DMX =.043355 SMN =-48605 SMX =67655 MN

- 4 60 5

-226

-35687 Residual stress analysis 289U2 54137

-9852 15984 41819 67655 Hoop Stress Figure 3-5: Post ID Weld Repair Residual Stress in the Unit 2 12" Hot Leg Surge Nozzle at 70'F.

(The units of the color bar across the bottom of the figures are psi.)

I Structural Integrity Associates, Inc.

0800692.404, Rev. 1 3-9 NODAL SOLUTION STEP=79 SUB -1 TIME-69 SY (AVG)

RSYS-O DMX =. 0433 55 SMN =-47 894 SMX =632 78 x

b..

-47894

-23189 1516 26221 50925

- 35542

-1 0837 13868 38573 63278 Rezidual

~tr e 33 analY3 i 3 NODAL SOLUTION STEP=79 SUB =1 TIME=69 SZ (AVG)

RSYS=O DMX =.043355 SMN =-48605 SMX =67655 Axial Stress x

L 48605 22769 3066 28902 54737

- 35687

- 9852 15984 41 819 67655 Re3idual 3tre~~ analy3i~

Hoop Stress Figure 3-5: Post ID Weld Repair Residual Stress in the Unit 2 12" Hot Leg Surge Nozzle at 70°F.

(The units of the color bar across the bottom of the figures are psi.)

0800692.404, Rev. 1 3-9

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Structural Integrity Associates, Inc.

AN NODAL SOLUTION STEP=2535 SUB =2 TIME=1016 SY (AVG)

RSYS-0 DMX -. 059158 SMN -- 38576 SMX -52119 x

-38576

-18422

-28499 Residual atres3 analysis 1733 21887 31964 42042 52119

-8344 11810 Axial Stress X

-72262

-44129

-58196 Residual stress analysis

-15997 12136 26202 40269 54335

-30063

-1930 Hoop Stress Figure 3-6: Post-WOL Residual Stresses in the Unit 2 12" Hot Leg Surge Nozzle at 70'F (The units of the color bar across the bottom of the figures are psi.)

0800692.404, Rev. 1 3-10 V

Structural Integrity Associates, Inc.

NODAL SOLUTION STEP~253 5 SUB =2 TIME=1016 SY

(.ZWG)

RSYS-O DMX -. 059158 SMN - -38576 SMX -52119 x L 3857 6

-18 422 1733 2188 7 420 4 2

- 28499

- 8344 11810 31964 52119 Re~idua l ~tr e 33 a na l y3 i ~

NODAL SOLUT I ON STEP=2535 SUB -2 TIME=1016 S2 (AVG)

RSYS=O DMX =. 059158 SMN =-72262 SMX

~54335 Axial Stress x

L 7 2262 44129 15997 1 2136 40269

-58196

-30063

-1930 26202 54335 Residual stress analysis Hoop Stress Figure 3-6: Post-WOL Residual Stresses in the Unit 2 12" Hot Leg Surge Nozzle at 70°F (The units of the color bar across the bottom of the figures are psi.)

0800692.404, Rev. 1 3-10

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Structural Integrity Associates, Inc.

rANtL NODAL SOLUTION STEP-2537 SUB =2 TIME 1036 SY (AVG)

RSYS-0 DMX

-. 275753 SMN -- 27300 SMX =43389

-27300

-11591 4117 19826 3553

-19446

-3737 11972 27680 Residual streas analysis 43389 Axial Stress AN NODAL SOLUTION STEP=2537 SUB

-2 TIME-l036 SZ (AVG)

RSYS=0 DMX =.275753 SMN =-46076 SMX =50156 X

-46076

-z4b,3l

-35384 Residual atreza analysis 180719

-13999 7386 28771 39464 50156 Hoop Stress Figure 3-7: Applied Post Weld Overlay Residual Stress in the Unit 2 12" Hot Leg Surge Nozzle at 611°F and 2235 psig (The units of the color bar across the bottom of the figures are psi.)

V Structural Integrity Associates, Inc.

0800692.404, Rev. I 3-11 NODAL SOLUTION STEP-2537 SUB -2 TIME-1036 SY (AVG)

RSYS-O DMX -. 275753 SMN --273 0 0 SMX -43389 x

L 27300 11591 4117 19826 35535

-19446

-3737 11972 27680 43389 Re~idual ~tre~s analy~is NODAL SOLUTION STEP-2537 SUB -2 TIME-1036 SZ (AVG)

RSYS=O DMX =. 275753 SMN =-46076 SMX =50156 Axial Stress x

1--

-46076

-2 4 69 1

-3306 18079 39464

- 35384

-13999 73 8 6 28771 50156 Re~idu6 1 ~Cre~~ ~no l y~i~

Hoop Stress Figure 3-7: Applied Post Weld Overlay Residual Stress in the Unit 2 12" Hot Leg Surge Nozzle at 611 of and 2235 psig (The units of the color bar across the bottom of the figures are psi.)

0800692.404, Rev. 1 3-11

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Structural Integrity Associates, Inc.

ID Surface Axial Residual Stress Post ID weld repair 70TF B Post butt weld 70TF

  • Postweld overlay 70°F Postweld overlay 611°F+2235psig 70 DMweld PipeWeld 60 Nozzle side Safe End Pipe side 50 40

-:30

-_=20M 10 A

-40 Distance from ID Weld Repair Centerline (in)

Figure 3-8: ID Surface Axial Stresses in the Unit 2 12" Hot Leg Surge Nozzle, Pre-and Post-overlay 0800692.404, Rev. 1 3-12 Structural Integrity Associates, Inc.

70 60 50 40

_30

'c;;

~20 If)

~ 10 as 0 10 Surface Axial Residual Stress

-+- Post 10 weld repair 70°F

-S-Post butt weld 70°F

-.\\- Post weld overlay 70°F

~

Post weld overlay611 °F+2235psig Nozzle side Pipe side

-10 t:-:;;#~#T~~~~-W~~!;;~~~-1

-20

-30

-40 Distance from 10 Weld Repair Centerline (in)

Figure 3-8: ID Surface Axial Stresses in the Unit 2 12" Hot Leg Surge Nozzle, Pre-and Post-overlay 0800692.404, Rev. 1 3-12 e Structural Integrity Associates, Inc.

ID Surface Hoop Residual Stress s Post ID weld repair 70TF E Postbuttweld 70TF A Postweld overlay 70TF Postweld overlay61 1'F+2235psig 80 60 40

-20 0

0-20

-40

-60

-80 Distance from ID Weld Repair Centerline (in)

Figure 3-9: ID Surface Hoop Stresses in the Unit 2 12" Hot Leg Surge Nozzle, Pre-and Post-overlay 0800692.404, Rev. 1 3-13 V

Structural Integrity Associates, Inc.

80 60 10 Surface Hoop Residual Stress

-+- Post 10 weld repair 70°F Post weld overlay 70°F

-+ OMWeld Nonie side safe End

-e-Postbuttweld 70°F

-e-Post weld overlay 611 ° F + 2235psig Pipe Weld Pipe side 40 +-----------~~~--~~--------~--------------------------~

40 +-----------~~~~-T~~~--~~r_------------------------~

-60

-80 Distance from 10 Weld Repair Centerline (in)

Figure 3-9: ID Surface Hoop Stresses in the Unit 2 12" Hot Leg Surge Nozzle, Pre-and Post-overlay 0800692.404, Rev. 1 3-13 l) Structural Integrity Associates, Inc.

4.0 EVALUATION OF WELD OVERLAY EFFECTS ON PIPING SYSTEMS

4.1 Background

Stresses may develop in remote locations of a piping system after application of one or more weld overlays in the system, due to the weld shrinkage of the overlays. These stresses are system-wide, and are similar in nature to restrained free end thermal expansion or contraction stresses. The level of stresses resulting from weld overlay shrinkage depends upon the amount of shrinkage that occurs and the piping system geometry (i.e., its stiffness).

In ASME Code terminology, weld overlay shrinkage stresses are secondary or peak stresses, and have no primary component. They are constant with time, so there are no ASME Code limits that apply to them, since Code limits on secondary and peak stresses apply to their range under cyclic loading conditions. They could, however, potentially increase the susceptibility of other susceptible welds in the system to future PWSCC. Therefore, it has become common practice with weld overlays to measure the shrinkage between punch marks that are placed on the piping and nozzles beyond the ends of the overlays as part of the implementation process. The stresses due to the measured shrinkage are then evaluated via a piping model. However, this was primarily a requirement for BWR weld overlays, in which the stainless steel systems contained multiple welds that were susceptible to intergranular stress corrosion cracking (IGSCC), and often contained more than one overlay. It is less of a concern in PWR overlay applications, because the PWSCC susceptibility in the systems is typically limited to the DMW that is being overlaid.

Due to displacements introduced by weld overlay shrinkage in the piping system, it is also required that, after application of the overlay, a walkdown be performed to check all hanger set points. In addition, clearances at all pipe whip restraints should be checked to ensure that they are within tolerance.

0800692.404, Rev. 1, 4-1 Structural Integrity Associates, Inc.

4.0 EVALUATION OF WELD OVERLAY EFFECTS ON PIPING SYSTEMS

4.1 Background

Stresses may develop in remote locations ofa piping system after application of one or more weld overlays in the system, due to the weld shrinkage of the overlays. These stresses are system-wide, and are similar in nature to restrained free end thermal expansion or contraction stresses. The level of stresses resulting from weld overlay shrinkage depends upon the amount of shrinkage that occurs and the piping system geometry (i.e., its stiffness).

In ASME Code terminology, weld overlay shrinkage stresses are secondary or peak stresses, and have no primary component. They are constant with time, so there are no ASME Code limits that apply to them, since Code limits on secondary and peak stresses apply to their range under cyclic loading conditions. They could, however, potentially increase the susceptibility of other susceptible welds in the system to future PWSCc. Therefore, it has become common practice with weld overlays to measure the shrinkage between punch marks that are placed on the piping and nozzles beyond the ends of the overlays as part of the implementation process. The stresses due to the measured shrinkage are then evaluated via a piping model. However, this was primarily a requirement for BWR weld overlays, in which the stainless steel systems contained multiple welds that were susceptible to intergranular stress corrosion cracking (IGSCC), and often contained more than one overlay. It is less of a concern in PWR overlay applications, because the PWSCC susceptibility in the systems is typically limited to the DMW that is being overlaid.

Due to displacements introduced by weld overlay shrinkage in the piping system, it is also required that, after application ofthe overlay, a walkdown be performed to check all hanger set points. In addition, clearances at all pipe whip restraints should be checked to ensure that they are within tolerance.

0800692.404, Rev. 1*

4-1 lJ Slruelurallnlegrity Associates, Inc.

4.2 Evaluation of Weld Overlay Shrinkage Stresses The weld overlay shrinkages, measured at four azimuthal locations around the nozzles during the repairs [15-20], are summarized in Table 4-1 for Unit 2 and in Table 4-2 for Unit 3. The average measured axial shrinkages were less than 0.4 inches for the Hot Leg Drain Nozzles for the two units, less than or equal to 0.15 inches for the Hot Leg Shutdown Cooling Nozzles, and less than 0.13 inches for the Hot Leg Surge Nozzles The hot leg drain line and shutdown cooling line are long flexible systems with relatively few supports. The axial shrinkage stresses are thus expected to be small, because of the relatively small shrinkage values and the very flexible systems. For the Hot Leg Surge Nozzles, the maximum measured axial shrinkage was 0.22 inches (one azimuthal location for Unit 3). The average shrinkage was less than 0.13 inches.

This shrinkage is relatively small, and hence shrinkage stresses in the surge line are expected to be small and judged to have no significant impact on stresses in the piping system.

Two models were constructed of the surge line piping and weld shrinkage was simulated to determine the resulting maximum stresses developed in the system, Appendix C (SI Calculation 0800692.303). The stresses determined by those models were for the surge piping. However, the surge piping is of equal or greater stiffness than the shutdown cooling and drain lines and has much more deflection due to shrinkage at both the pressurizer and hot leg nozzles. Thus, it is anticipated that the surge line shrinkage stresses bound those of the shutdown cooling and drain lines.

The highest stress caused by the overlay shrinkage is found to be 393 psi for Unit 2, and 730 psi for Unit 3. Stress at the weld to the Hot Leg Surge Nozzle is 214 psi for Unit 2 and 532 psi for Unit 3. Since the expected weld shrinkage stress at this location is roughly 0.532 ksi or less, it is judged to be acceptable.

All hangers, supports, and restraints that may be potentially affected were checked by SCE personnel after the application of the overlay repairs, and they were all found to be acceptable with the exception of a surge line jet impingement guide in Unit 3, which experienced 0800692.404, Rev. 1 4-2 V

Structural Integrity Associates, Inc.

4.2 Evaluation of Weld Overlay Shrinkage Stresses The weld overlay shrinkages, measured at four azimuthal locations around the nozzles during the repairs [15-20], are summarized in Table 4-1 for Unit 2 and in Table 4-2 for Unit 3. The average measured axial shrinkages were less than 0.4 inches for the Hot Leg Drain Nozzles for the two units, less than or equal to 0.15 inches for the Hot Leg Shutdown Cooling Nozzles, and less than 0.13 inches for the Hot Leg Surge Nozzles The hot leg drain line and shutdown cooling line are long flexible systems with relatively few supports. The axial shrinkage stresses are thus expected to be small, because of the relatively small shrinkage values and the very flexible systems. For the Hot Leg Surge Nozzles, the maximum measured axial shrinkage was 0.22 inches (one azimuthal location for Unit 3). The average shrinkage was less than 0.13 inches.

This shrinkage is relatively small, and hence shrinkage stresses in the surge line are expected to be small and judged to have no significant impact on stresses in the piping system.

Two models were constructed of the surge line piping and weld shrinkage was simulated to determine the resulting maximum stresses developed in the system, Appendix C (SI Calculation 0800692.303). The stresses determined by those models were for the surge piping. However, the surge piping is of equal or greater stiffness than the shutdown cooling and drain lines and has much more deflection due to shrinkage at both the pressurizer and hot leg nozzles. Thus, it is anticipated that the surge line shrinkage stresses bound those of the shutdown cooling and drain lines.

The highest stress caused by the overlay shrinkage is found to be 393 psi for Unit 2, and 730 psi for Unit 3. Stress at the weld to the Hot Leg Surge Nozzle is 214 psi for Unit 2 and 532 psi for Unit 3. Since the expected weld shrinkage stress at this location is roughly 0.532 ksi or less, it is judged to be acceptable.

All hangers, supports, and restraints that may be potentially affected were checked by SCE personnel after the application of the overlay repairs, and they were all found to be acceptable with the exception of a surge line jet impingement guide in Unit 3, which experienced 0800692.404, Rev. 1 4-2 tr Structural Integrity Associates, Inc.

unacceptable displacement and will be repaired during the next outage [21]. The present condition of this support was evaluated and found acceptable for continued service until it can be repaired [21 ].

Thus, the observed shrinkage levels are deemed to be acceptable.

4.3 Evaluation of the Effect of Weld Overlay Weight The weight added to the piping systems by the weld overlays has been calculated based on maximum design dimensions, and is summarized in Table 4-3. Using the maximum design dimensions is conservative since the as-built overlay dimensions documented in References 15 through 20 fall within the minimum and maximum design dimensions. The calculated weight includes the total weight of the overlay as well as the effective weight of the overlay on the piping. The table also lists conservative estimates of the weight of the piping systems (from standard piping schedules). Reconciliation of as-built WOL weights for impact on loads and dynamic response is presented in Sections 4.3.1 and 4.3.2.

4.3.1 Dead Weight A summary of the dead weight of the WOL compared to the weight of the piping is presented in Appendix B (SI Calculation 0800692.302). This calculation addresses the different configurations for the Unit 2 and Unit 3 Hot Leg Surge Nozzle weld overlays. The Unit 2 geometry was modified to shorten the minimum overlay, however the maximum overlay was not changed. Therefore, the maximum model from SI Calculation 0800692.312 remains bounding for Unit 2. The Unit 3 geometry was modified to cover the pup piece to elbow weld and SI Calculation 800692.342 reflects this geometry in the finite element model. The weight calculation, SI Calculation 0800692.302, includes Unit 3 as well. The total weight of the WOL ranges from about 13 lbs to 260 lbs for the different nozzles (Table 4-3). However, a significant portion of the WOL is on the nozzle side. The boundary between the nozzle and the piping system is assumed to be the midpoint of the safe end-to-pipe weld, and is the typical anchor point for piping system analyses. Therefore, the effective WOL weight on the piping system is much 0800692.404, Rev. 1 4-3 Structural Integrity Associates, Inc.

unacceptable displacement and will be repaired during the next outage [21]. The present condition of this support was evaluated and found acceptable for continued service until it can be repaired [21].

Thus, the observed shrinkage levels are deemed to be acceptable.

4.3 Evaluation of the Effect of Weld Overlay Weight The weight added to the piping systems by the weld overlays has been calculated based on maximum design dimensions, and is summarized in Table 4-3. Using the maximum design dimensions is conservative since the as-built overlay dimensions documented in References 15 through 20 fall within the minimum and maximum design dimensions. The calculated weight includes the total weight of the overlay as well as the effective weight of the overlay on the piping. The table also lists conservative estimates of the weight of the piping systems (from standard piping schedules). Reconciliation of as-built WOL weights for impact on loads and dynamic response is presented in Sections 4.3.1 and 4.3.2.

4.3.1 Dead Weight A summary of the dead weight of the WOL compared to the weight of the piping is presented in Appendix B (SI Calculation 0800692.302). This calculation addresses the different configurations for the Unit 2 and Unit 3 Hot Leg Surge Nozzle weld overlays. The Unit 2 geometry was modified to shorten the minimum overlay, however the maximum overlay was not changed. Therefore, the maximum model from SI Calculation 0800692.312 remains bounding for Unit 2. The Unit 3 geometry was modified to cover the pup piece to elbow weld and SI Calculation 800692.342 reflects this geometry in the finite element model. The weight calculation, SI Calculation 0800692.302, includes Unit 3 as well. The total weight of the WOL ranges from about 13 lbs to 260 lbs for the different nozzles (Table 4-3). However, a significant portion of the WOL is on the nozzle side. The boundary between the nozzle and the piping system is assumed to be the midpoint of the safe end-to-pipe weld, and is the typical anchor point for piping system analyses. Therefore, the effective WOL weight on the piping system is much 0800692.404, Rev. 1 4-3 f! Structural Integrity Associates, Inc.

smaller, ranging from about 2 lbs to 140 lbs (Table 4-3). In the worst case, the added weight is less than 8% of the piping weight based on conservative WOL maximum design dimensions and piping weight estimates. Overall, the added WOL weight would have negligible impact on design loads and stresses.

4.3.2 Dynamic Response While the system mass is slightly increased, the WOL also adds stiffness to the system. Hence, any increase in mass is compensated for by an increase in stiffness resulting in an insignificant change in the system frequency. Additionally, since the added mass of the WOL is concentrated in the vicinity of the anchor point, which is the assumed boundary at the midpoint of the safe end-to-pipe weld, the effect of the added mass on the dynamic characteristics of the piping system would be insignificant.

0800692.404, Rev. 1 4-4 Structural Integrity Associates, Inc.

smaller, ranging from about 2 lbs to 140 lbs (Table 4-3). In the worst case, the added weight is less than 8% of the piping weight based on conservative WOL maximum design dimensions and piping weight estimates. Overall, the added WOL weight would have negligible impact on design loads and stresses.

4.3.2 Dynamic Response While the system mass is slightly increased, the WOL also adds stiffness to the system. Hence, any increase in mass is compensated for by an increase in stiffness resulting in an insignificant change in the system frequency. Additionally, since the added mass of the WOL is concentrated in the vicinity of the anchor point, which is the assumed boundary at the midpoint of the safe end-to-pipe weld, the effect of the added mass on the dynamic characteristics of the piping system would be insignificant.

0800692.404, Rev. 1 4-4 l) Structural Integrity Associates, Inc.

Table 4-1: Weld Overlay Shrinkage Measurements-Unit 2 Hot Leg Hot Hot Leg Description Location Shutdown Leg Drain Cooling Surge Nozzle Nozzle Nozzle 00 0.08 0.026 0.39 Axial 900 0.14 0.031 0.35 Shrinkage 1800 0.16 0.031 0.41 (in.)

2700 0.22 0.143 0.33 Average 0.15 0.058 0.37 (in.)

Table 4-2: Weld Overlay Shrinkage Measurements-Unit 3 Hot Leg Hot Hot Leg Description Location Shutdown Leg Drain Cooling Surge Nozzle Nozzle Nozzle 00 0.001) 0.14 0.30 Axial 900 0.12 0.22 0.38 Shrinkage 1800 0.02 0.11 0.36 (in.)

I 2700 0.05 0.03 0.23 Average 0.063 0.125 0.318 (in.)

1. Zero value is conservatively ignored for calculation of average shrinkage Note:

V Structural Integrity Associates, Inc.

0800692.404, Rev. 1 4-5 Table 4-1: Weld Overlay Shrinkage Measurements-Unit 2 Hot Leg Hot Hot Leg Description Location Shutdown Leg Drain Cooling Surge Nozzle Nozzle Nozzle 0° 0.08 0.026 0.39 Axial 90° 0.14 0.031 0.35 Shrinkage 180° 0.16 0.031 0.41 (in.)

270° 0.22 0.143 0.33 Average 0.15 0.058 0.37 (in.)

Table 4-2: Weld Overlay Shrinkage Measurements-Unit 3 Hot Leg Hot Hot Leg Description Location Shutdown Leg Drain Cooling Surge Nozzle Nozzle Nozzle 0° 0.0(1) 0.14 0.30 Axial 90° 0.12 0.22 0.38 Shrinkage 180° 0.02 0.11 0.36 (in.)

270° 0.05 0.03 0.23 Average 0.063 0.125 0.318 (in.)

Note:

1. Zero value is conservatively ignored for calculation of average shrinkage 0800692.404, Rev. 1 4-5

() Structural Integrity Associates, Inc.

Table 4-3: Design Maximum Overlay Weight Summary-Unit 2 and Unit 3 Hot Leg Drain Leg Surge Hot Leg Hot Leg Surge Nozzle Shutdown Nozzle Nozzle Unit 2 Cooling Nozzle Unit 3 Total WOL Volume (in3) 45.1 501.6 692.6 885.6 WOL Volume (in3) to be 8.3 153.4 213.6 478.9 Applied to Piping(l) pWOL (lb/in3) 0.293 0.293 0.293 0.293 Total WOL Weight (lb) 13.2 147.0 202.9 259.5 WOL Weight (lb) to be 2.4 44.9 62.6 140.3 Applied to Piping(l)

Nominal Piping Weight (per 8.43 195.16 301.08 195.16 ft), with water System Piping Length (ft) 5.64(2) 9.00(3) 8.6414) 9.0003)

Piping Weight (lb) 47.5 1756 2601 1756

% Weight Added to Piping 5.0 2.6 2.4 8.0 System Notes:

(1)

WOL volume/weight added to piping system.

(2)

Piping length to first rigid support location. Unit 3's shorter pipe length is used for calculation.

(3)

Piping length from first elbow to second elbow. Unit 3's shorter pipe length is used for calculation.

(4)

Piping length from first elbow to second elbow. The shorter length from Unit 2 is used.

Structural Integrity Associates, Inc.

Table 4-3: Design Maximum Overlay Weight Summary-Unit 2 and Unit 3 Hot Leg Surge Hot Leg Hot Leg Drain Nozzle Shutdown Nozzle Unit 2 Cooling Nozzle Total WOL Volume (in3) 45.1 501.6 692.6 WOL Volume (in3) to be 8.3 153.4 213.6 Applied to Piping(1) pWOL (lb/in3) 0.293 0.293 0.293 Total WOL Weight (lb) 13.2 147.0 202.9 WOL Weight (lb) to be 2.4 44.9 62.6 Applied to Piping(l)

Nominal Piping Weight (per 8.43 195.16 301.08 ft), with water System Piping Length (ft) 5.64(2) 9.00(3) 8.64(4)

Piping Weight (lb) 47.5 1756 2601

% Weight Added to Piping 5.0 2.6 2.4 System Notes:

(1)

WOL volume/weight added to piping system.

(2)

Piping length to first rigid support location. Unit 3 's shorter pipe length is used for calculation.

(3)

Piping length from first elbow to second elbow. Unit 3's shorter pipe length is used for calculation.

(4)

Piping length from first elbow to second elbow. The shorter length from Unit 2 is used.

Hot Leg Surge Nozzle Unit 3 885.6 478.9 0.293 259.5 140.3 195.16 9.00(3) 1756 8.0 0800692.404, Rev. 1 4-6

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Structural Integrity Associates, Inc.

5.0 CRACK GROWTH EVALUATIONS

5.1 Background

In this section, growth of cracks that may potentially exist in the overlaid DMWs is considered for both PWSCC and fatigue mechanisms. Crack growth evaluations were performed to demonstrate that flaws equal to or greater than the maximum flaw sizes that may escape detection during ultrasonic examination would not show unacceptable growth, so as to violate the basis for the overlay design.

5.2 Technical Approach The technical approach used in this evaluation is to determine the through-wall stress intensity factor (K) distribution associated with assumed axial and circumferential flaws in the DMWs and stainless steel butt welds using the post-weld overlay residual stresses at operating conditions plus sustained and transient operating stresses. If the K distribution with sustained operating stresses is such that it is negative at the crack tip, then no PWSCC growth is predicted [11]. The maximum depth crack for which this condition is true represents the flaw tolerance depth, below which no PWSCC growth is predicted. From a fatigue crack growth standpoint, the K distributions for both the maximum and minimum cyclic stresses during various plant transients are determined, and bounded by enveloping the transients. The Kmin and Kmax calculations include both applied and residual stresses. Fatigue crack growth is then computed using crack growth laws appropriate for Alloy 82/182 weld metal and austenitic stainless steel (where applicable) [12, 13] at the DMW in a pressurized water reactor (PWR) environment. Fatigue crack growth in the stainless steel weld is calculated using the austenitic stainless steel fatigue crack growth law in air from Article C-3210 of the ASME Code,Section XI [3]. Factors (>1) are applied to this rate to account for the PWR environment. In implementing the crack growth law, it is assumed that no crack growth will occur if both Kmin and Kmax are less than zero. If Kmax is positive during any part of a transient, then the fatigue crack growth is calculated to determine how many years growth can occur until a postulated initial flaw reaches the base metal/overlay interface or grows into the overlay without violating minimum thickness 0 2 R Structural Integrity Associates, Inc.

5.0 CRACK GROWTH EVALUATIONS 5.t'

Background

In this section, growth of cracks that may potentially exist in the overlaid DMWs is considered for both PWSCC and fatigue mechanisms. Crack growth evaluations were performed to demonstrate that flaws equal to or greater than the maximum flaw sizes that may escape detection during ultrasonic examination would not show unacceptable growth, so as to violate the basis for the overlay design.

5.2 Technical Approach The technical approach used in this evaluation is to determine the through-wall stress intensity factor (K) distribution associated with assumed axial and circumferential flaws in the DMWs and stainless steel butt welds using the post-weld overlay residual stresses at operating conditions plus sustained and transient operating stresses. If the K distribution with sustained operating stresses is such that it is negative at the crack tip, then no PWSCC growth is predicted [11]. The maximum depth crack for which this condition is true represents the flaw tolerance depth, below which no PWSCC growth is predicted. From a fatigue crack growth standpoint, the K distributions for both the maximum and minimum cyclic stresses during various plant transients are determined, and bounded by enveloping the transients. The Kmin and Kmax calculations, include both applied and residual stresses. Fatigue crack growth is then computed using crack growth laws appropriate for Alloy 82/182 weld metal and austenitic stainless steel (where applicable) [12, 13] at the DMW in a pressurized water reactor (PWR) environment. Fatigue crack growth in the stainless steel weld is calculated using the austenitic stainless steel fatigue crack growth law in air from Article C-321 0 of the ASME Code,Section XI [3]. Factors (> 1) are applied to this rate to account for the PWR environment. In implementing the crack growth law, it is assumed that no crack growth will occur ifboth Kmin and Kmax are less than zero. If Kmax is positive during any part of a transient, then the fatigue crack growth is calculated to determine how many years growth can occur until a postulated initial flaw reaches the base metal/overlay interface or grows into the overlay without violating minimum thickness 0800692.404, Rev. 1 5-1 l) Structural Integrity Associates, Inc.

requirements, using the defined number of cycles for each transient. Negative Kmin values are addressed via R-ratio corrections.

Stresses that contribute to fatigue crack growth include stresses due to primary loads, such as internal pressure and external piping loads, secondary loads, such as thermal gradient stresses (due to thermal transient events) and local stratification stresses (for the Hot Leg Surge Nozzle only), and residual stresses. The through-wall stresses from these loads are extracted from the finite element analyses and fitted to a third order polynomial for subsequent crack growth analyses. Details of the various loads, finite element analyses, and stress analyses are discussed in Section 6.0 of this report.

Fracture mechanics models, which are representative for the nozzle geometry, are used to determine stress intensity factors, K. The model with minimum overlay dimensions is used for pressure, mechanical load; and residual stresses, while the model with maximum overlay dimensions is used for thermal transient stresses. For circumferential flaws under uniform axial load, a 3600 flaw in a cylinder with the actual thickness-to-radius ratios are used. For circumferential flaws with moment loading, a 360' flaw in a cylinder with the actual inside radius-to-outside radius ratio is used. For axial flaws, a semi-elliptical inside surface flaw with an aspect ratio (depth-to-length) of 0.2 in a cylinder is used for fatigue crack growth, and an aspect ratio of 0.5 for PWSCC. The stress intensity factors for each type of load are computed as a function of assumed crack depth in the original weld, and superimposed for the various operation states. Fatigue crack growth (or combined fatigue crack growth and PWSCC growth if PWSCC is active) is calculated by using linear elastic fracture mechanics (LEFM) techniques. Crack growth laws for Alloy 82/Alloy 182 weld metals, stainless steel, and Alloy 52M weld metal, when crack growth is predicted to extend into the weld overlay, with multipliers to account for a pressurized water reactor environment, are used. Crack growth is calculated to determine the number of years it takes for a postulated initial flaw of 75% of the original base metal thickness to reach the base metal/overlay interface or grow into the overlay without violating minimum thickness requirements.

0800692.404, Rev. 1 5-2 U

Structural Integrity Associates, Inc.

requirements, using the defined number of cycles for each transient. Negative Kmin values are addressed via R-ratio corrections.

Stresses that contribute to fatigue crack growth include stresses due to primary loads, such as internal pressure and external piping loads, secondary loads, such as thermal gradient stresses (due to therynal transient events) and local stratification stresses (for the Hot Leg Surge Nozzle only), and residual stresses. The through-wall stresses from these loads are extracted from the finite element analyses and fitted to a third order polynomial for subsequent crack growth analyses. Details of the various loads, finite element analyses, and stress analyses are discussed in Section 6.0 of this report.

Fracture mechanics models, which are representative for the nozzle geometry, are used to determine stress intensity factors, K. The model with minimum overlay dimensions is used for pressure, mechanical load; and residual stresses, while the model with maximum overlay dimensions is used for thermal transient stresses. For circumferential flaws under uniform axial load, a 360 0 flaw in a cylinder with the actual thickness-to-radius ratios are used. For circumferential flaws with moment loading, a 360 0 flaw in a cylinder with the actual inside radius-to-outside radius ratio is used. For axial flaws, a semi-elliptical inside surface flaw with an aspect ratio (depth-to-length) of 0.2 in a cylinder is used for fatigue crack growth, and an aspect ratio of 0.5 for PWSCc. The stress intensity factors for each type of load are computed as a function of assumed crack depth in the original weld, and superimposed for the various operation states. Fatigue crack growth (or combined fatigue crack growth and PWSCC growth ifPWSCC is active) is calculated by using linear elastic fracture mechanics (LEFM) techniques. Crack growth laws for Alloy 821 Alloy 182 weld metals, stainless steel,

\\

and Alloy 52M weld metal, when crack growth is predicted to extend into the weld overlay, with multipliers to account for a pressurized water reactor environment, are used. Crack growth is calculated to determine the number of years it takes for a postulated initial flaw of 75% of the original base metal thickness to reach the base metal/overlay interface or grow into the overlay without violating minimum thickness requirements.

0800692.404, Rev. 1 5-2 tJ Strueturallntegrity Associates, Inc.

PWSCC potential in the DMW is determined by calculating the stress intensity factor versus crack depth (K-vs.-a) curve at normal steady state operating conditions. For the PWSCC evaluation, the fracture mechanics models used are the same as those used in the fatigue crack growth calculations.

Crack growth analysis details and results are contained in Appendix J (SI Calculation 0800692.316) for the Hot Leg Shutdown Cooling Nozzle, Appendix R (SI Calculation 0800692.326) for the Unit 2 Hot Leg Surge Nozzle, Appendix GG (SI Calculation 0800692.346) for the Unit 3 Hot Leg Surge Nozzle, and Appendix AA (SI Calculation 0800692.336) for the Hot Leg Drain Nozzle.

5.3 Crack Growth Results 5.3.1 Hot Leg Shutdown Cooling Nozzle Table 5-1 presents the results of the fatigue crack growth and PWSCC growth calculation for the circumferential and axial flaws in the DMW and stainless steel weld. For a circumferential flaw and an axial flaw in the DMW, the time it takes for an initial flaw of 75% of the original thickness to reach the overlay is greater than 40 years.

The analysis showed that PWSCC became active at a flaw depth of 89.3% of the original base metal thickness at the DMW analyzed section for the circumferential flaw and 90.5% of the original base metal thickness at the DMW analyzed section for the axial flaw, respectively.

At the SSW, it takes 39 years for an initial flaw of 75% of the original base metal thickness at the analyzed section to reach the overlay for the circumferential flaw and greater than 40 years for the axial flaw.

Details of the analysis and results are presented in Appendix J (SI Calculation 0800692.316).

0800692.404, Rev. 1 5-3 Structural Integrity Associates, Inc.

PWSCC potential in the DMW is determined by calculating the stress intensity factor versus crack depth (K-vs.-a) curve at normal steady state operating conditions. For the PWSCC evaluation, the fracture mechanics models used are the same as those used in the fatigue crack growth calculations.

Crack growth analysis details and results are contained in Appendix J (SI Calculation 0800692.316) for the Hot Leg Shutdown Cooling Nozzle, Appendix R (SI Calculation 0800692.326) for the Unit 2 Hot Leg Surge Nozzle, Appendix GG (SI Calculation 0800692.346) for the Unit 3 Hot Leg Surge Nozzle, and Appendix AA (SI Calculation 0800692.336) for the Hot Leg Drain Nozzle.

5.3 Crack Growth Results 5.3.1 Hot Leg Shutdown Cooling Nozzle Table 5-1 presents the results of the fatigue crack growth and PWSCC growth calculation for the circumferential and axial flaws in the DMW and stainless steel weld. For a circumferential flaw and an axial flaw in the DMW, the time it takes for an initial flaw of75% of the original thickness to reach the overlay is greater than 40 years.

The analysis showed that PWSCC became active at a flaw depth of89.3% of the original base metal thickness at the DMW analyzed section for the circumferential flaw and 90.5% of the original base metal thickness at the DMW analyzed section for the axial flaw, respectively.

At the SSW, it takes 39 years for an initial flaw of75% of the original base metal thickness at the analyzed section to reach the overlay for the circumferential flaw and greater than 40 years for the axial flaw.

Details of the analysis and results are presented in Appendix J (SI Calculation 0800692.316).

0800692.404, Rev. 1 5-3 lJ Slruclurallnlegrily Associates, Inc.

5.3.2 Hot Leg Surge Nozzle-Unit 2 Table 5-1 presents the results of the crack growth calculation for the circumferential and axial flaws in the DMW for the Unit 2 Hot Leg Surge Nozzle. Both nozzle-to-safe end and safe end-to-pipe weld locations are evaluated using bounding stresses. At the DMW, it takes greater than 11 years for an initial flaw of 75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and greater than 40 years for an axial flaw.

At the SSW, it takes greater than 11 years for an initial flaw of 75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and greater than 40 years for an axial flaw.

The analysis showed that PWSCC became active at a flaw depth of 79% of the original base metal thickness at the DMW analyzed section for the circumferential flaw. For the axial flaw, the analysis showed that the stress intensity factor is negative at normal operating conditions (NOC) through the original base metal thickness. Therefore, there is no PWSCC concern at the DMW location for an axial flaw between 75% and 100% of the original base metal thickness.

Details of the analysis and results are presented in Appendix R (SI Calculation 0800692.326) 5.3.3 Hot Leg Surge Nozzle-Unit 3 Table 5-1 presents the results of the crack growth calculation for the circumferential and axial flaws in the DMW for the Unit 3 Hot Leg Surge Nozzle, including the pup piece. Both nozzle-to-safe end and safe end-to-pipe weld locations are evaluated using bounding stresses. At the DMW, it takes greater than 40 years for an initial flaw of 75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and greater than 40 years for an axial flaw.

At each of the SS welds, it takes greater than 40 years for an initial flaw of 75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and greater than 40 years for an axial flaw.

0800692.404, Rev. 1 5-4 Structural Integrity Associates, Inc.

5.3.2 Hot Leg Surge Nozzle-Unit 2 Table 5-1 presents the results of the crack growth calculation for the circumferential and axial flaws in the DMW for the Unit 2 Hot Leg Surge Nozzle. Both nozzle-to-safe end and safe end-to-pipe weld locations are evaluated using bounding stresses. At the DMW, it takes greater than 11 years for an initial flaw of75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and greater than 40 years for an axial flaw.

At the SSW, it takes greater than 11 years for an initial flaw of75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and greater than 40 years for an axial flaw.

The analysis showed that PWSCC became active at a flaw depth of 79% of the original base metal thickness at the DMW analyzed section for the circumferential flaw. For the axial flaw, the analysis showed that the stress intensity factor is negative at normal operating conditions (NOC) through the original base metal thickness. Therefore, there is no PWSCC concern at the DMW location for an axial flaw between 75% and 100% of the original base metal thickness.

Details of the analysis and results are presented in Appendix R (SI Calculation 0800692.326) 5.3.3 Hot Leg Surge Nozzle-Unit 3 Table 5-1 presents the results of the crack growth calculation for the circumferential and axial flaws in the DMW for the Unit 3 Hot Leg Surge Nozzle, including the pup piece. Both nozzle-to-safe end and safe end-to-pipe weld locations are evaluated using bounding stresses. At the DMW, it takes greater than 40 years for an initial flaw of75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and greater than 40 years for an axial flaw.

At each of the SS welds, it takes greater than 40 years for an initial flaw of75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and greater than 40 years for an axial flaw.

0800692.404, Rev. 1 5-4

!lJ Strueturallntegrity Associates, Inc.

For both the circumferential flaw and axial flaw, the analysis showed that the stress intensity factor is negative at normal operating conditions (NOC) through the original base metal thickness. Therefore, there is no PWSCC growth expected at the DMW.

Details of the analysis and results are presented in Appendix GG (SI Calculation 0800692.346).

5.3.4 Hot Leg Drain Nozzle Table 5-1 presents the results of the crack growth calculation for the circumferential and axial flaws in the DMW. At the DMW, it takes greater than 40 years for an initial flaw of 75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and an axial flaw.

At the SSW, it takes 37 years for an initial flaw of 75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and greater than 40 years for an axial flaw.

For PWSCC, the analysis showed that the stress intensity factor is negative at normal operating conditions (NOC) through the original base metal thickness for both the circumferential and axial flaw. Therefore, there is no PWSCC concern at the DMW location for the circumferential and axial flaw between 75% and 100% of the original base metal thickness.

Details of the analysis and results are presented in Appendix AA (SI Calculation 0800692.336) for the Hot Leg Drain Nozzle, Appendix J (SI Calculation 0800692.316) for the Hot Leg Shutdown Cooling Nozzle, Appendix R (SI Calculation 0800692.326) for the Unit 2 Hot Leg Surge Nozzle, and in Appendix GG (SI Calculation 0800692.346) for the Unit 3 Hot Leg Surge Nozzle.

Structural Integrity Associates, Inc.

For both the circumferential flaw and axial flaw, the analysis showed that the stress intensity factor is negative at normal operating conditions (NOC) through the original base metal thickness. Therefore, there is no PWSCC growth expected at the DMW.

Details of the analysis and results are presented in Appendix GG (SI Calculation 0800692.346).

5.3.4 Hot Leg Drain Nozzle Table 5-1 presents the results of the crack growth calculation for the circumferential and axial flaws in the DMW. At the DMW, it takes greater than 40 years for an initial flaw of75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and an axial flaw.

At the SSW, it takes 37 years for an initial flaw of75% of the original base metal thickness at the analyzed section to reach the overlay for a circumferential flaw and greater than 40 years for an axial flaw.

For PWSCC, the analysis showed that the stress intensity factor is negative at normal operating conditions (NOC) through the original base metal thickness for both the circumferential and axial flaw. Therefore, there is no PWSCC concern at the DMW location for the circumferential and axial flaw between 75% and 100% of the original base metal thickness.

Details of the analysis and results are presented in Appendix AA (SI Calculation 0800692.336) for the Hot Leg Drain Nozzle, Appendix J (SI Calculation 0800692.316) for the Hot Leg Shutdown Cooling Nozzle, Appendix R (SI Calculation 0800692.326) for the Unit 2 Hot Leg Surge Nozzle, and in Appendix GG (SI Calculation 0800692.346) for the Unit 3 Hot Leg Surge Nozzle.

0800692.404, Rev. 1 5-5 l) Siruelurallntegrity Associates, Inc.

Table 5-1: Limiting Crack Growth Results - Hot Leg Nozzles Time to Reach Overlay Hot Leg Hot Leg Hot Leg Hot Leg Drain Surge Surge Shutdown Nozzle Nozzle Cooling Nozzle Unit 2 Unit 3(2)

Nozzle Circumferential

>40 years

>11 years

>40 years

>40 years (DMW)

Axial (DMW)

>40 years

>40 years

>40 years

>40 years Circumferential

>40 years (2)/

SS welds 37 years

>11 years

>40 years (2) 39 years

>40 years(2)/

Axial SS welds

>40 years

>40 years

>40 years(2)

>40 years Notes: (1) DMW = Dissimilar metal weld; SSW = Stainless steel weld.

(2) Contains both a safe end to pup piece SSW and pup piece to elbow SSW.

0800692.404, Rev. 1 Structural Integrity Associates, Inc.

5-6 Table 5-1: Limiting Crack Growth Results - Hot Leg Nozzles Time to Reach Overlay Hot Leg Hot Leg Hot Leg Hot Leg Flaw(l)

Surge Surge Shutdown Drain Nozzle Nozzle Nozzle Cooling Unit 2 Unit 3(2)

Nozzle Circumferential

>40 years

> 11 years

>40 years

>40 years (DMW)

Axial (DMW)

>40 years

>40 years

>40 years

>40 years Circumferential 37 years

> 11 years

>40 years(2)/

39 years SS welds

>40 years(2)

Axial SS welds

>40 years

>40 years

>40 years(2) /

>40 years

>40 years(2)

Notes: (1) DMW = DIssImIlar metal weld; SSW = Stamless steel weld.

(2) Contains both a safe end to pup piece SSW and pup piece to elbow SSW.

0800692.404, Rev. 1 5-6 tJ Structural Integrity Associates, Inc.

6.0 ASME SECTION III STRESS ANALYSES 6.1 Background -

This section presents a summary of ASME Code,Section III stress evaluations performed for the weld overlays on the Hot Leg Shutdown Cooling Nozzle, the Hot Leg Surge Nozzle, the Hot Leg Drain Nozzle.

ASME Code,Section III, 1998 Edition with Addenda through 2000 [14] was used for these evaluations. Reconciliation of a later Code with the applicable Code-of-Record is discussed in Section 7.0.

6.2 Design Criteria The weld overlay repairs are designed to the requirements of the ASME Code,Section III for Class 1 components.

For the Hot Leg Shutdown Cooling, the Hot Leg Surge and the Hot Leg Drain Nozzles, the nozzle portion and the affected piping of the repair are evaluated to satisfy Subarticle NB-3200 acceptance criteria, with guidance from the rules of Subarticle NB-3600.

6.3 Technical Approach Stresses at critical locations due to various loading conditions are determined using finite element analyses. Applicable design loads and thermal transients are documented in Appendix E (SI Calculation 0800692.311) for the Hot Leg Shutdown Cooling Nozzle, Appendix M (SI Calculation 0800692.321) for the Hot Leg Surge Nozzle and Appendix V (SI Calculation 0800692.331) for the Hot Leg Drain Nozzle.

Details of the finite element models developed using the computer program ANSYS [9] are presented in Appendix F (SI Calculation 0800692.312) for the Hot Leg Shutdown Cooling Nozzle, Appendix N (SI Calculation 0800692.322) for the Unit 2 Hot Leg Surge Nozzle, 0800692.404, Rev. 1 6-1 V

Structural Integrity Associates, Inc.

6.0 ASME SECTION III STRESS ANALYSES 6.1 Background*

This section presents a summary of ASME Code,Section III stress evaluations performed for the weld overlays on the Hot Leg Shutdown Cooling Nozzle, the Hot Leg Surge Nozzle, the Hot Leg Drain Nozzle.

ASME Code,Section III, 1998 Edition with Addenda through 2000 [14] was used for these evaluations. Reconciliation of a later Code with the applicable Code-of-Record is discussed in Section 7.0.

6.2 Design Criteria The weld overlay repairs are designed to the requirements of the ASME Code,Section III for Class 1 components.

For the Hot Leg Shutdown Cooling, the Hot Leg Surge and the Hot Leg Drain Nozzles, the nozzle portion and the affected piping of the repair are evaluated to satisfy Subarticle NB-3200 acceptance criteria, with guidance from the rules of Subarticle NB-3600.

6.3 Technical Approach Stresses at critical locations due to various loading conditions are determined using finite element analyses. Applicable design loads and thermal transients are documented in Appendix E (SI Calculation 0800692.311) for the Hot Leg Shutdown Cooling Nozzle, Appendix M (SI Calculation 0800692.321) for the Hot Leg Surge Nozzle and Appendix V (SI Calculation 0800692.3 31) for the Hot Leg Drain Nozzle.

Details of the finite element models developed using the computer program ANSYS [9] are presented in Appendix F (Sl Calculation 0800692.312) for the Hot Leg Shutdown Cooling Nozzle, Appendix N (SI Calculation 0800692.322) for the Unit 2 Hot Leg Surge Nozzle, 0800692.404, Rev. 1 6-1 l) Structural Integrity Associates, Inc.

Appendix CC (SI Calculation 0800692.342) for the Unit 3 Hot Leg Surge Nozzle and Appendix W (SI Calculation 0800692.332) for the Hot Leg Drain Nozzle.

Stress analyses are presented in Appendix G (SI Calculation 0800692.313) for the Hot Leg Shutdown Cooling Nozzle, Appendix 0 (SICalculation 0800692.323) for the Unit 2 Hot Leg Surge Nozzle, Appendix DD (SI Calculation 0800692.343) for the Unit 3 Hot Leg Surge Nozzle and Appendix X (SI Calculation 0800692.333) for the Hot Leg Drain Nozzle.

Details of the ASME Code,Section III evaluations are contained in Appendix I (SI Calculation 0800692.315) for the Hot Leg Shutdown Cooling Nozzle, Appendix Q (SI Calculation 0800692.325) for the Unit 2 Hot Leg Surge Nozzle, Appendix FF (SI Calculation 0800692.345) for the Unit 3 Hot Leg Surge Nozzle and Appendix Z (SI Calculation 0800692.335) for the Hot Leg Drain Nozzle.

The Relief Requests, which are based on Code Case N-504-2 and N-638-1, require that the overlay be sized so that it will be able to provide for load redistribution from the pipe into the deposited weld metal and back into the nozzle without violating applicable stress limits of ASME Code,Section III. This was demonstrated in the sizing calculations discussed in Section 2.3 of this report.

The weld overlay sizing evaluations, discussed in Section 2.3 of this report, considered general primary membrane, Pm, and primary membrane-plus-bending, Pm + Pb, stress intensities resulting from normal/upset (Service Levels A and B) operating conditions and emergency/faulted (Service Levels C and D) conditions. While local primary membrane, PL, stress intensities were not specifically evaluated, any local stress effects due to the weld overlay repair are expected to be minimal. The sizing calculations did not specifically evaluate loads resulting from the Test Load Combinations. However, the Test Load Combinations consider only primary stresses which only result from pressure and mechanical loads. The added thickness of the weld overlay will only serve to reduce the general primary 0800692.404, Rev. 1 6-2

U Structural Integrity Associates, Inc.

Appendix CC (SI Calculation 0800692.342) for the Unit 3 Hot Leg Surge Nozzle and Appendix W (SI Calculation 0800692.332) for the Hot Leg Drain Nozzle.

Stress analyses are presented in Appendix G (SI Calculation 0800692.313) for the Hot Leg Shutdown Cooling Nozzle, Appendix 0 (SI.Calculation 0800692.323) for the Unit 2 Hot Leg Surge Nozzle, Appendix DD (SI Calculation 0800692.343) for the Unit 3 Hot Leg Surge Nozzle and Appendix X (SI Calculation 0800692.333) for the Hot Leg Drain Nozzle.

Details of the ASME Code,Section III evaluations are contained in Appendix I (SI Calculation 0800692.315) for the Hot Leg Shutdown Cooling Nozzle, Appendix Q (SI Calculation 0800692.325) for the Unit 2 Hot Leg Surge Nozzle, Appendix FF (SI Calculation 0800692.345) for the Unit 3 Hot Leg Surge Nozzle and Appendix Z (SI Calculation 0800692.335) for the Hot Leg Drain Nozzle.

The Relief Requests, which are based on Code Case N-504-2 and N-638-1, require that the overlay be sized so that it will be able to provide for load redistribution from the pipe into the deposited weld metal and back into the nozzle without violating applicable stress limits of ASME Code,Section III. This was demonstrated in the sizing calculations discussed in Section 2.3 of this report.

The weld overlay sizing evaluations, discussed in Section 2.3 of this report, considered general primary membrane, Pm, and primary membrane-pIus-bending, Pm + Pb, stress intensities resulting from normal/upset (Service Levels A and B) operating conditions and emergency/faulted (Service Levels C and D) conditions. While local primary membrane, PL, stress intensities were not specifically evaluated, any local stress effects due to the weld overlay repair are expected to be minimal. The sizing calculations did not specifically evaluate loads resulting from the Test Load Combinations. However, the Test Load Combinations consider only primary stresses which only result from pressure and mechanical loads. The added thickness of the weld overlay will only serve to reduce the general primary 0800692.404, Rev. 1 6-2 l) Slruclurallnlegrily Associates, Inc.

membrane, Pm, and local primary membrane, PL, stress intensities and are not expected to be adversely affected when compared to the original configuration.

Therefore, the only load combinations which will be considered in detail herein are for Service Levels A and B, primary-plus-secondary, and primary-plus-secondary-plus-peak effects.

6.4 Results of Analyses 6.4.1 Hot Leg Shutdown Cooling Nozzle Stress intensities for the weld overlaid Hot Leg Shutdown Cooling Nozzle are determined from finite element analyses for the various specified load combinations, as discussed in Section 6.3.

Linearized through-wall stresses were evaluated through a total of nine stress paths. The stress intensities along all these paths are evaluated in accordance with ASME Code,Section III, Subarticles NB-3200 and NB-3600 [14], and compared to the applicable Code limits. A summary of the stress comparison for the most limiting locations is provided in Table 6-1. The stresses and the fatigue usage in the weld overlaid Hot Leg Shutdown Cooling Nozzle are within the applicable Code limits.

6.4.2 Hot Leg Surge Nozzle-Unit 2 Stress intensities for the weld overlaid Unit 2 Hot Leg Surge Nozzle are determined from finite element analyses for the various specified load combinations, as discussed in Section 6.3.

Linearized through-wall stresses were evaluated through a total of six stress paths. The stress intensities along these paths are evaluated in accordance with ASME Code,Section III, Subarticles NB-3200 and NB-3600 [14], and compared to the applicable Code limits. A summary of the stress comparison for the most limiting locations is provided in Table 6-2. The stresses and the fatigue usage in the weld overlaid Unit 2 Hot Leg Surge Nozzle are within the applicable Code limits.

0800692.404, Rev. 1 6-3 Structural Integrity Associates, Inc.

membrane, Pm, and local primary membrane, PL, stress intensities and are not expected to be adversely affected when compared to the original configuration.

Therefore, the only load combinations which will be considered in detail herein are for Service Levels A and B, primary-pIus-secondary, and primary-plus-secondary-plus-peak effects.

6.4 Results of Analyses 6.4.1 Hot Leg Shutdown Cooling Nozzle J

Stress intensities for the weld overlaid Hot Leg Shutdown Cooling Nozzle are determined from finite element analyses for the various specified load combinations, as discussed in Section 6.3.

Linearized through-wall stresses were evaluated through a total of nine stress paths. The stress intensities along all these paths are evaluated in accordance with ASME Code,Section III, Subartic1es NB-3200 and NB-3600 [14], and compared to the applicable Code limits. A summary of the stress comparison for the most limiting locations is provided in Table 6-1. The stresses and the fatigue usage in the weld overlaid Hot Leg Shutdown Cooling Nozzle are within the applicable Code limits.

6.4.2 Hot Leg Surge Nozzle-Unit 2 Stress intensities for the weld overlaid Unit 2 Hot Leg Surge Nozzle are determined from finite element analyses for the various specified load combinations, as discussed in Section 6.3.

Linearized through-wall stresses were evaluated through a total of six stress paths. The stress intensities along these paths are evaluated in accordance with ASME Code,Section III, Subartic1es NB-3200 and NB-3600 [14], and compared to the applicable Code limits. A summary of the stress comparison for the most limiting locations is provided in Table 6-2. The stresses and the fatigue usage in the weld overlaid Unit 2 Hot Leg Surge Nozzle are within the applicable Code limits.

0800692.404, Rev. 1 6-3 tJ Siruciurallniegrily Associates, Inc.

6.4.3 Hot Leg Surge Nozzle-Unit 3 Stress intensities for the weld overlaid Unit 3 Hot Leg Surge Nozzle are determined from finite element analyses for the various specified load combinations, as discussed in Section 6.3.

Linearized through-wall stresses were evaluated through a total of 12 stress paths. The stress intensities along these paths are evaluated in accordance with ASME Code,Section III, Subarticles NB-3200 and NB-3600 [14], and compared to the applicable Code limits. A summary of the stress comparison for the most limiting locations is provided in Table 6-3. The stresses and the fatigue usage in the weld overlaid Unit 3 Hot Leg Surge Nozzle are within the applicable Code limits.

6.4.4 Hot Leg Drain Nozzle Stress intensities for the weld overlaid Hot Leg Drain Nozzle are determined from finite element analyses for the various specified load combinations, as discussed in Section 6.3. Linearized through-wall stresses were evaluated through a total of six stress paths. The stress intensities along these paths are evaluated in accordance with ASME Code,Section III, Subarticles NB-3200 and NB-3600 [14], and compared to the applicable Code limits. A summary of the stress comparison for the most limiting locations is provided in Table 6-4. The stresses and the fatigue usage in the weld overlaid Hot Leg Drain Nozzle are within the applicable Code limits.

6.5 Concluding Remarks Evaluations have been performed to ensure that the weld overlay repairs on the Hot Leg Shutdown Cooling, the Hot Leg Surge and the Hot Leg Drain Nozzles meet the applicable ASME Code,Section III limits. The evaluations show that all ASME Code limits have been met.

Structural Integrity Associates, Inc.

6.4.3 Hot Leg Surge Nozzle-Unit 3 Stress intensities for the weld overlaid Unit 3 Hot Leg Surge Nozzle are determined from finite element analyses for the various specified load combinations, as discussed in Section 6.3.

Linearized through-wall stresses were evaluated through a total of 12 stress paths. The stress intensities along these paths are evaluated in accordance with ASME Code,Section III, Subartic1es NB-3200 and NB-3600 [14], and compared to the applicable Code limits. A summary of the stress comparison for the most limiting locations is provided in Table 6-3. The stresses and the fatigue usage in the weld overlaid Unit 3 Hot Leg Surge Nozzle are within the applicable Code limits.

6.4.4 Hot Leg Drain Nozzle Stress intensities for the weld overlaid Hot Leg Drain Nozzle are determined from finite element analyses for the various specified load combinations, as discussed in Section 6.3. Linearized through-wall stresses were evaluated through a total of six stress paths. The stress intensities along these paths are evaluated in accordance with ASME Code,Section III, Subartic1es NB-3200 and NB-3600 [14], and compared to the applicable Code limits. A summary of the stress comparison for the most limiting locations is provided in Table 6-4. The stresses and the fatigue usage in the weld overlaid Hot Leg Drain Nozzle are within the applicable Code limits.

6.5 Concluding Remarks Evaluations have been performed to ensure that the weld overlay repairs on the Hot Leg Shutdown Cooling, the Hot Leg Surge and the Hot Leg Drain Nozzles meet the applicable ASME Code,Section III limits. The evaluations show that all ASME Code limits have been met.

0800692.404, Rev. 1 6-4

!l) Structural Integrity Associates, Inc.

Table 6-1: Limiting Stress Results for Hot Leg Shutdown Cooling Nozzle Load Path and Type(d)

Calculated Allowable Combination Path a

nd (P

C Allowable Path 1 Primary + Secondary (P + Q) (ksi) (a) 38.941 49.536 Path 2 Primary + Secondary (P + Q) (ksi) (a) 40.097 49.536 Path 3 Primary + Secondary (P + Q) (ksi)(a) 39.221 49.536 Path 4 Primary + Secondary (P + Q) (ksi)(a) (c) 34.581 50.736 Level A/B Path 6 Primary + Secondary (P + Q) (ksi) (a) (c) 31.622 51.210 Path 6 Primary + Secondary (P + Q) (ksi) (a)(c) 31.563 50.736 Path 7 Primary + Secondary (P + Q) (ksi) (a) 48.362 50.736 Path 8 Primary + Secondary (P + Q) (ksi)(a) 47.991 50.736 Path 9 Primary + Secondary (P +/- Q) (ksi) (a) 46.65 6 50.73 6 Fatigue Cumulative Usage Factor (b) 0.523 1.000 (a)

Primary stress acceptance criteria are met via the sizing calculations discussed in Section 2.3 (b)

The limiting fatigue usage location is at the outside surface at the elbow near the SSW.

(c)

Elastic analysis exceeds the allowable values of 3Sm; however, criteria for simplified elastic-plastic analysis are met as shown.

(d)

Path definitions are provided in Appendix I.

Table 6-2: Limiting Stress Results for Hot Leg Surge Nozzle-Unit 2 Load Path and Type(c)

Calculated Allowable Combination Path 1 Primary + Secondary (P + Q) (ksi) (a) 41.035 56.096 Path 2 Primary + Secondary (P + Q) (ksi) (a) 34.399 49.920 Level A/B Path 3 Primary + Secondary (P + Q) (ksi) (a) 49.285 49.855 Path 4 Primary + Secondary (P + Q) (ksi)(a) 37.278 56.096 Path 5 Primary + Secondary (P + Q) (ksi) (a) 34.733 49.920 Path 6 Primary + Secondary (P + Q) (ksi) (a) 48.887 49.855 Fatigue Cumulative Usage Factor (b) 0.300 1.000 (a)

Primary stress acceptance criteria are met via the sizing calculations discussed in Section 2.3 (b)

The limiting fatigue usage location is at the outside surface at the nozzle near the DMW.

(c)

Path definitions are provided in Appendix Q.

Structural Integrity Associates, Inc.

Table 6-1: Limiting Stress Results for Hot Leg Shutdown Cooling Nozzle Load Path and Type(d)

Calculated Combination Path 1 Primary + Secondary (P + Q) (ksi) (a) 38.941 Path 2 Primary + Secondary (P + Q) (ksi) (a) 40.097 Path 3 Primary + Secondary (P + Q) (ksi) (a) 39.221 Path 4 Primary + Secondary (P + Q) (ksi)(a) (e) 34.581 Level AlB Path 5 Primary + Secondary (P + Q) (ksi) (a) (e) 31.622 Path 6 Primary + Secondary (P + Q) (ksi) (a) (e) 31.563 Path 7 Primary + Secondary (P + Q) (ksi) (a) 48.362 Path 8 Primary + Secondary (P + Q) (ksi) (a) 47.991 Path 9 Primary + Secondary (P + Q) (ksi) (a) 46.656 Fatigue Cumulative Usage Factor (b) 0.523 (a)

Pnmary stress acceptance cntena are met VIa the slzmg calculatlOns dIscussed m SectlOn 2.3 (b)

The limiting fatigue usage location is at the outside surface at the elbow near the SSW.

Allowable 49.536 49.536 49.536 50.736 51.210 50.736 50.736 50.736 50.736 1.000 (c)

Elastic analysis exceeds the allowable values of 3Sm; however, criteria for simplified elastic-plastic analysis are met as shown.

(d)

Path definitions are provided in Appendix I.

Table 6-2: Limiting Stress Results for Hot Leg Surge Nozzle-Unit 2 Load Path and Type(e)

Calculated Combination Path I Primary + Secondary (P + Q) (ksi) (a) 41.035 Path 2 Primary + Secondary (P + Q) (ksi) (a) 34.399 Level AlB Path 3 Primary + Secondary (P + Q) (ksi) (a) 49.285 Path 4 Primary + Secondary (P + Q) (ksi)(a) 37.278 Path 5 Primary + Secondary (P + Q) (ksi) (a) 34.733 Path 6 Primary + Secondary (P + Q) (ksi) (a) 48.887 Fatigue Cumulative Usage Factor (b) 0.300 (a)

Primary stress acceptance criteria are met via the sizing calculations discussed in Section 2.3 (b)

The limiting fatigue usage location is at the outside surface at the nozzle near the DMW.

(c)

Path definitions are provided in Appendix Q.

Allowable 56.096 49.920 49.855 56.096 49.920 49.855 1.000 0800692.404, Rev. 1 6-5 l) Structural Integrity Associates, Inc.

Table 6-3: Limiting Stress Results for Hot Leg Surge Nozzle-Unit 3 Load Combination Path and Type(d)

Calculated Allowable Path 1 Primary + Secondary (P + Q) (ksi) (a)(C) 43.854 48.624 Path 2 Primary + Secondary (P + Q) (ksi) (a) 38.053 50.208 Path 3 Primary + Secondary (P + Q) (ksi)(a) 36.714 50.208 Path 4 Primary + Secondary (P + Q) (ksi)(a) 30.688 52.182 Path 5 Primary + Secondary (P + Q) (ksi) () (c) 38.636 48.612 Path 6 Primary + Secondary (P + Q) (ksi)(a) 42.125 50.208 Level A/B Path 7 Primary + Secondary (P + Q) (ksi)j()

38.373 50.208 Path 8 Primary + Secondary (P + Q) (ksi)(a) 35.494 52.182 Path 9 Primary + Secondary (P + Q) (ksi)(a) 43.529 48.672 Path 10 Primary + Secondary (P + Q) (ksi)(a) 40.680 50.208 Path 11 Primary + Secondary (P + Q) (ksi) (a) 38.762 50.208 Path 12 Primary + Secondary (P + Q) (ksi)(a) 34.344 52.182 Fatigue Cumulative Usage Factor (b) 0.330 1.000 (a)

Primary stress acceptance criteria are met via the sizing calculations discussed in Section 2.3 (b)

The limiting fatigue usage location is at the outside surface at the intrados of the elbow at the toe of the overlay.

(c)

Elastic analysis exceeds the allowable values of 3sm; however, criteria for simplified elastic-plastic analysis are met as shown.

(d)

Path definitions are provided in Appendix FF.

Table 6-4: Limiting Stress Results for Hot Leg Drain Nozzle Load Path and Type(d)

Calculated Allowable Combination Path 1 Primary + Secondary (P + Q) (ksi) () (c) 20.636 49.440 Path 2 Primary + Secondary (P + Q) (ksi) (a) (c) 35.151 50.616 Path 3 Primary + Secondary (P + Q) (ksi) (a) (c) 44.182 50.616 Level A/B Path 4 Primary + Secondary (P + Q) (kSi)(a) (C) 18.739 49.440 Path 5 Primary + Secondary (P + Q) (ksi) (a) (c) 25.570 50.616 Path 6 Primary + Secondary (P + Q) (ksi) (a) (c) 43.356 50.616 Fatigue Cumulative Usage Factor (b) 0.366 1.000 (a)

Primary stress acceptance criteria are met via the sizing calculations discussed in Section 2.3 (b)

The limiting fatigue usage location is at the outside surface at the pipe near the SSW.

(c)

Elastic analysis exceeds the allowable values of 3Sm; however, criteria for simplified elastic-plastic analysis are met as shown.

(d)

Path definitions are provided in Appendix Z.

006 40 Structural Integrity Associates, Inc.

Table 6-3: Limiting Stress Results for Hot Leg Surge Nozzle-Unit 3 Load Combination Path and Type(d)

Calculated Allowable Path 1 Primary + Secondary (P + Q) (ksi) (a) (e) 43.854 48.624 Path 2 Primary + Secondary (P + Q) (ksi) (a) 38.053 50.208 Path 3 Primary + Secondary (P + Q) (ksi) (a) 36.714 50.208 Path 4 Primary + Secondary (P + Q) (ksi/a) 30.688 52.182 Path 5 Primary + Secondary (P + Q) (ksi) (a) (e) 38.636 48.612 Level AlB Path 6 Primary + Secondary (P + Q) (ksi) (a) 42.125 50.208 Path 7 Primary + Secondary (P + Q) (ksi) (a) 38.373 50.208 Path 8 Primary + Secondary (P + Q) (ksi) (a) 35.494 52.182 Path 9 Primary + Secondary (P + Q) (ksi) (a) 43.529 48.672 Path 10 Primary + Secondary (P + Q) (ksi) (a) 40.680 50.208 Path 11 Primary + Secondary (P + Q) (ksi) (a) 38.762 50.208 Path 12 Primary + Secondary (P + Q) (ksi) (a) 34.344 52.182 Fatigue Cumulative Usage Factor (b) 0.330 1.000 (a)

Primary stress acceptance criteria are met via the sizing calculations discussed in Section 2.3 (b)

The limiting fatigue usage location is at the outside surface at the intrados of the elbow at the toe of the overlay.

(c)

Elastic analysis exceeds the allowable values of 3Sm; however, criteria for simplified elastic-plastic analysis are met as shown.

(d)

Path definitions are provided in Appendix FF.

Table 6-4: Limiting Stress Results for Hot Leg Drain Nozzle Load Path and Type(d)

Calculated Combination Path 1 Primary + Secondary (P + Q) (ksi) (aJ (eJ 20.636 Path 2 Primary + Secondary (P + Q) (ksi) (a) (e) 35.151 Level AlB Path 3 Primary + Secondary (P + Q) (ksi) (a) (eJ 44.182 Path 4 Primary + Secondary (P + Q) (ksi)(a) (e) 18.739 Path 5 Primary + Secondary (P + Q) (ksi) (a) (e) 25.570 Path 6 Primary + SecondaryJP + Q) (ksi) (a) (e) 43.356 Fatigue Cumulative Usage Factor (b) 0.366 (a)

Primary stress acceptance criteria are met via the sizing calculations discussed in Section 2.3 (b)

The limiting fatigue usage location is at the outside surface at the pipe near the SSW.

Allowable 49.440 50.616 50.616 49.440 50.616 50.616 1.000 (c)

Elastic analysis exceeds the allowable values of3Sm; however, criteria for simplified elastic-plastic analysis are met as shown.

(d)

Path definitions are provided in Appendix Z.

0800692.404, Rev. 1 6-6

~

Structural Integrity Associates, Inc.

7.0 RECONCILIATION OF CODE-OF-RECORD TO LATER CODE EDITION The applicable ASME Code-of-Record for the Hot Leg Nozzles (RCS Piping) is the 1974 Edition with Addenda through Summer 1974.

The Code (i.e., the replacement Code in lieu of the Code-of-Record) for the weld overlay repairs is the 1998 Edition (with Addenda through 2000) of ASME Code,Section III [14]. Material properties are also based on the 1998 Edition (with Addenda through 2000). This section of the report provides the reconciliations which document the acceptability of using a different Code edition, or revised Owner's requirements, by meeting the ASME Code,Section XI, 1995 Edition (with Addenda through 1996) [3], IWA-4170 requirements, and demonstrates that the repairs are satisfactory for the specified design and operating conditions.

7.1 Design For the design of the weld overlay repairs, Subarticles NB-3200 and NB-3600 of the replacement Code (1998 Edition with Addenda through 2000) are adopted.

The design criteria in Subarticle NB-3200 of the original Code-of-Record (ASME Code,Section III, 1974 Edition with Addenda through Summer 1974) are basically the same as those of Subarticle NB-3200 of the replacement Code. For Service Level D limits, the intent of NB-3225 and Appendix F of the replacement Code is consistent with that of NB-3225 of the original Code-of-Record, which is to provide assurance that violation of the pressure boundary does not occur.

NB-3611.2 of the replacement Code and the original Code-of-Record permit the use of the alternative requirements of Subarticle NB-3200. The requirements of Subarticle NB-3200 of the replacement Code and the original Code-of-Record are similar.

7.2 Fabrication No parts were fabricated; therefore, no Code reconciliation is needed.

0800692.404, Rev. 1 7-1 Structural Integrity Associates, Inc.

7.0 RECONCILIATION OF CODE-OF-RECORD TO LATER CODE EDITION The applicable ASME Code-of-Record for the Hot Leg Nozzles (RCS Piping) is the 1974 Edition with Addenda through Summer 1974.

The Code (i.e., the replacement Code in lieu of the Code-of-Record) for the weld overlay repairs is the 1998 Edition (with Addenda through 2000) of ASME Code,Section III [14]. Material properties are also based on the 1998 Edition (with Addenda through 2000). This section of the report provides the reconciliations which document the acceptability of using a different Code edition, or revised Owner's requirements, by meeting the ASME Code,Section XI, 1995 Edition (with Addenda through 1996) [3], IW A-4170 requirements, and demonstrates that the repairs are satisfactory for the specified design and operating conditions.

7.1 Design For the design of the weld overlay repairs, Subarticles NB-3200 and NB-3600 of the replacement Code (1998 Edition with Addenda through 2000) are adopted.

The design criteria in Subarticle NB-3200 of the original Code-of-Record (ASME Code,Section III, 1974 Edition with Addenda through Summer 1974) are basically the same as those of Subarticle NB-3200 of the replacement Code. For Service Level D limits, the intent ofNB-3225 and Appendix F of the replacement Code is consistent with that ofNB-3225 of the original Code-of-Record, which is to provide assurance that violation of the pressure boundary does not occur.

NB-3611.2 of the replacement Code and the original Code-of-Record permit the use of the alternative requirements of Subarticle NB-3200. The requirements of Subarticle NB-3200 of the replacement Code and the original Code-of-Record are similar.

7.2 Fabrication No parts were fabricated; therefore, no Code reconciliation is needed.

0800692.404, Rev. 1 7-1 t; Structural Integrity Associates, Inc.

7.3 Examination Examination requirements for Weld overlay repairs are per the Relief Requests [2], which are based on ASME Code Case N-504-2 and N-638-1 [I ]; thus, no reconciliation is needed.

7.4 Materials The ASME Code,Section II, 1998 Edition (with Addenda through 2000) is used for all materials since the original Code-of-Record does not contain properties for Alloy 52M weld metal (Alloy 690 base material). The fatigue strength curve is essentially unchanged between the original Code (ASME Code,Section III, 1974 Edition with Addenda through Summer 1974) and the replacement Code (ASME Code,Section III, 1998 Edition with Addenda through 2000) for Ni-Cr-Fe material. The differences in the coefficients of thermal expansion, modulus of elasticity, and thermal properties between the original Code-of-Record and the replacement Code for materials (i.e., ASME Code,Section II, 1998 Edition, with Addenda through 2000) reflect improvements in the understanding of the material.

7.5 Conclusion It is concluded that the rules in the 1998 Edition (with Addenda through 2000) of Section III of the ASME Code, with material properties from the 1998 Edition (with Addenda through 2000) of Section II, are acceptable for use in the evaluations contained herein, and the replacement Code is considered to be reconciled with the Code-of-Record.

Structural Integrity Associates, Inc.

7.3 Examination Examination requirements for weld overlay repairs are per the Relief Requests [2], which are based on ASME Code Case N-504-2 and N-638-1[1]; thus, no reconciliation is needed.

7.4 Materials The ASME Code,Section II, 1998 Edition (with Addenda through 2000) is used for all materials since the original Code-of-Record does not contain properties for Alloy 52M weld metal (Alloy 690 base material). The fatigue strength curve is essentially unchanged between the original Code (ASME Code,Section III, 1974 Edition with Addenda through Summer 1974) and the replacement Code (ASME Code,Section III, 1998 Edition with Addenda through 2000) for Ni-Cr-Fe material. The differences in the coefficients of thermal expansion, modulus of elasticity, and thermal properties between the original Code-of-Record and the replacement Code for materials (i.e., ASME Code,Section II, 1998 Edition, with Addenda through 2000) reflect improvements in the understanding of the material.

7.S Conclusion It is concluded that the rules in the 1998 Edition (with Addenda through 2000) of Section III of the ASME Code, with material properties from the 1998 Edition (with Addenda through 2000) of Section II, are acceptable for use in the evaluations contained herein, and the replacement Code is considered to be reconciled with the Code-of-Record.

0800692.404, Rev. 1 7-2 lJ Structural Integrity Associates, Inc.

8.0 EVALUATION OF AS-BUILT CONDITIONS Weld overlays add mass to the piping system and may impact dead weight loads and the dynamic characteristics of the existing piping systems. The effects of the added WOL mass on the piping systems are evaluated in Section 4.0. Additionally, finite element models (including WOLs), with bounding dimensions based on design drawings, are used in stress calculations.

Field measurements documented in References 15 through 20 have shown that the as-built weld overlay dimensions and configurations for the Unit 2 and 3 hot leg shutdown cooling, surge and drain welds conform to the design drawing requirements, with the exception of those addressed in the Welding Services Inc. nonconformance reports in References 22, 23, and 24. All hangers, supports, and restraints that may be potentially affected were checked by SCE personnel after the application of the overlay repairs, and they were all found to be acceptable with the exception of a surge line jet impingement guide in Unit 3 that will be repaired during the next outage. This support, although requiring repair, was found acceptable for continued operation. This is discussed in Section 4.2 [21].

The nonconformance reports are discussed in Sections 8.1 through 8.3.

8.1 NCR No.08-223 NCR No.08-223 [22] addresses a nonconformance on the SONGS Unit 3 Shutdown Cooling (SDC) Nozzle as built condition, measured during final weld overlay dimensioning. The nonconformance is that the weld overlay dimension from the elbow side toe of the safe end-to-elbow weld to the end of the overlay is greater than the allowed tolerance. The design length allowance (SI Drawing 0800692.510) is 2.88" minimum, 3.38" maximum. The as-built condition ranges in length between 3.48" and 3.54".

All overlay thicknesses are within tolerance. All other overlay dimensions are within tolerance.

In addition the angle of the end slope at the elbow meets the minimum 1350 included angle.

Structural Integrity Associates, Inc.

8.0 EVALUATION OF AS-BUILT CONDITIONS Weld overlays add mass to the piping system and may impact dead weight loads and the dynamic characteristics of the existing piping systems. The effects of the added WOL mass on the piping systems are evaluated in Section 4.0. Additionally, finite element models (including WOLs), with bounding dimensions based on design drawings, are used in stress calculations.

Field measurements documented in References 15 through 20 have shown that the as-built weld overlay dimensions and configurations for the Unit 2 and 3 hot leg shutdown cooling, surge and drain welds conform to the design drawing requirements, with the exception of those addressed in the Welding Services Inc. nonconformance reports in References 22, 23, and 24. All hangers, supports, and restraints that may be potentially affected were checked by SCE personnel after the application of the overlay repairs, and they were all found to be acceptable with the exception of a surge line jet impingement guide in Unit 3 that will be repaired during the next outage. This support, although requiring repair, was found acceptable for continued operation. This is discussed in Section 4.2 [21].

The nonconformance reports are discussed in Sections 8.1 through 8.3.

8.1 NCR No.08-223 NCR No.08-223 [22] addresses a nonconformance on the SONGS Unit 3 Shutdown Cooling (SDC) Nozzle as built condition, measured during final weld overlay dimensioning. The nonconformance is that the weld overlay dimension from the elbow side toe of the safe end-to-elbow weld to the end of the overlay is greater than the allowed tolerance. The design length allowance (SI Drawing 0800692.510) is 2.88" minimum, 3.38" maximum. The as-built condition ranges in length between 3.48" and 3.54".

All overlay thicknesses are within tolerance. All other overlay dimensions are within tolerance.

In addition the angle of the end slope at the elbow meets the minimum 135° included angle.

0800692.404, Rev. 1 8-1

~

Structural Integrity Associates, Inc.

The disposition of NCR No.08-223 is to "use-as-is". The "use-as-is" basis results from the determination that there exists no adverse effects of the additional length on the weld overlay sizing calculation, including shear load transfer (0800692.310), nor on the finite element model calculation (0800692.312), nor the ASME Code,Section III evaluation (0800692.315), nor on the crack growth evaluation (0800692.316), nor the axial shrinkage (0800692.303), nor the WOL weight (0800692.302). With this justification, the nonconformance report is accepted using the "as-is" geometry. Additional details are provided in Reference 22.

8.2 NCR No.09-281 NCR No.09-281 [23] addresses a nonconformance on the SONGS Unit 2 Hot Leg (HL) Drain Nozzle as built condition, measured during the initial weld overlay layout. The nonconformance is that the diameter of the nozzle boss is slightly less than the design dimension. The design dimension (SI Drawing 0800692.530): 5.44" diameter whereas the as-built diameter ranges between 5.41" and 5.43".

All overlay thicknesses will be within minimum and maximum tolerances, so there is no adverse impact on the mechanical load capability of the overlay or increased thermal stresses due to increased overlay thickness. All other overlay dimensions are anticipated to be within tolerance.

In addition, the angle of the WOL end slope at the nozzle end is still configured to make a smooth transition into the nozzle and match the nozzle diameter.

The disposition of NCR No.09-281 is to "use-as-is". The "use-as-is" basis results from the determination that there exists no adverse effects of the additional length on the weld overlay sizing calculation, including shear load transfer (0800692.330), nor on the finite element model calculation (0800692.332), nor the ASME Code,Section III evaluation (0800692.335), nor on the crack growth evaluation (0800692.336), nor the axial shrinkage (0800692.303), nor the WOL weight (0800692.302). With this justification, the nonconformance report is accepted using the "as-is" geometry. No subsequent nonconformance was identified at the time of final as-installed measurements. Additional details are provided in Reference 23.

0800692.404, Rev. 1 8-2 V

Structural Integrity Associates, Inc.

The disposition of NCR No.08-223 is to "use-as-is". The "use-as-is" basis results from the determination that there exists no adverse effects of the additional length on the weld overlay sizing calculation, including shear load transfer (0800692.310), nor on the finite element model calculation (0800692.312), nor the ASME Code,Section III evaluation (0800692.315), nor on the crack growth evaluation (0800692.316), nor the axial shrinkage (0800692.303), nor the WOL weight (0800692.302). With this justification, the nonconformance report is accepted using the "as-is" geometry. Additional details are provided in Reference 22.

8.2 NCR No.09-281 NCR No.09-281 [23] addresses a nonconformance on the SONGS Unit 2 Hot Leg (HL) Drain Nozzle as built condition, measured during the initial weld overlay layout. The nonconformance is that the diameter of the nozzle boss is slightly less than the design dimension. The design dimension (SI Drawing 0800692.530): 5.44" diameter whereas the as-built diameter ranges between 5.41" and 5.43".

All overlay thicknesses will be within minimum and maximum tolerances, so there is no adverse impact on the mechanical load capability of the overlay or increased thermal stresses due to increased overlay thickness. All other overlay dimensions are anticipated to be within tolerance.

In addition, the angle of the WOL end slope at the nozzle end is still configured to make a smooth transition into the nozzle and match the nozzle diameter.

The disposition of NCR No.09-281 is to "use-as-is". The "use-as-is" basis results from the determination that there exists no adverse effects of the additional length on the weld overlay sizing calculation, including shear load transfer (0800692.330), nor on the finite element model calculation (0800692.332), nor the ASME Code,Section III evaluation (0800692.335), nor on the crack growth evaluation (0800692.336), nor the axial shrinkage (0800692.303), nor the WOL weight (0800692.302). With this justification, the nonconformance report is accepted using the "as-is" geometry. No subsequent nonconformance was identified at the time of final as-installed measurements. Additional details are provided in Reference 23.

0800692.404, Rev. 1 8-2 l) Structural Integrity Associates, Inc.

8.3 NCR No.09-282 NCR No.09-282 [24] addresses a nonconformance on the SONGS Unit 2 Shutdown Cooling Nozzle related to the weld overlay length dimension. The elbow side toe of the safe end-to-elbow weld to the end of the overlay is greater than the allowed tolerance. The design allowance (SI Drawing 0800692.510) is 2.88" minimum, 3.38" maximum. The as-built condition ranges between 3.37" and 3.94".

All overlay thicknesses are within minimum and maximum tolerances, so there is no adverse impact on the mechanical load capability of the overlay or increased thermal stresses (due to increased overlay thickness). The overlay surface profile also meets the flatness tolerance, thus intermediate thicknesses are also per design requirements. All other overlay dimensions are within tolerance. In addition, the angle of the end slope at the elbow meets the minimum 1350 included angle.

The length dimension on the flat part (OD surface) of the overlay beyond the safe end-to-elbow weld is within tolerance. Thus there is sufficient length of this "platform" for an ultrasonic examination to be performed. Therefore, there is no adverse impact on the NDE. Subsequently the UT examination was successfully performed, with no limitations in this area.

The disposition of NCR No.09-282 is to "use-as-is". The "use-as-is" basis results from the determination that there exists no adverse effects of the additional length on the weld overlay sizing calculation, including shear load transfer (0800692.310), nor on the finite element model calculation (0800692.312), nor the ASME Code,Section III evaluation (0800692.315), nor on the crack growth evaluation (0800692.316), nor the axial shrinkage (0800692.303), nor the WOL weight (0800692.302). With this justification, the nonconformance report is accepted using the "as-is" geometry. Additional details are provided in Reference 24.

0800692.404, Rev. 1 8-3 Structural Integrity Associates, Inc.

8.3 NCR No.09-282 NCR No.09-282 [24] addresses a nonconformance on the SONGS Unit 2 Shutdown Cooling Nozzle related to the weld overlay length dimension. The elbow side toe of the safe end-to-elbow weld to the end of the overlay is greater than the allowed tolerance. The design allowance (SI Drawing 0800692.510) is 2.88" minimum, 3.38" maximum. The as-built condition ranges between 3.37" and 3.94".

All overlay thicknesses are within minimum and maximum tolerances, so there is no adverse impact on the mechanical load capability of the overlay or increased thermal stresses (due to increased overlay thickness). The overlay surface profile also meets the flatness tolerance, thus intermediate thicknesses are also per design requirements. All other overlay dimensions are within tolerance. In addition, the angle of the end slope at the elbow meets the minimum 135° included angle.

The length dimension on the flat part (OD surface) of the overlay beyond the safe end-to-elbow weld is within tolerance. Thus there is sufficient length of this "platform" for an ultrasonic examination to be performed. Therefore, there is no adverse impact on the NDE. Subsequently the UT examination was successfully performed, with no limitations in this area.

The disposition of NCR No.09-282 is to "use-as-is". The "use-as-is" basis results from the determination that there exists no adverse effects of the additional length on the weld overlay sizing calculation, including shear load transfer (0800692.310), nor on the finite element model calculation (0800692.312), nor the ASME Code,Section III evaluation (0800692.315), nor on the crack growth evaluation (0800692.316), nor the axial shrinkage (0800692.303), nor the WOL weight (0800692.302). With this justification, the nonconformance report is accepted using the "as-is" geometry. Additional details are provided in Reference 24.

0800692.404, Rev. 1 8-3 tr Structural Integrity Associates, Inc.

9.0

SUMMARY

AND CONCLUSIONS This report provides a summary of the weld overlay design and analyses for the dissimilar metal welds in the Hot Leg Surge, Hot Leg Shutdown Cooling and Hot Leg Drain Nozzles at the San Onofre Nuclear Generating Station, Units 2 and 3. The design of these overlays was performed in accordance with requirements of the Relief Requests [2], which are based on ASME Code Case N-504-2 and N-638-1[1]. Consolidation calculations were completed for each weld overlay design (Appendix K for the Hot Leg Shutdown Cooling Nozzle, Appendix S for the Hot Leg Surge Nozzle (which includes Appendix T for additional analyses completed on the Unit 2 Hot Leg Surge Nozzle), and Appendix BB for the Hot Leg Drain Nozzle). These consolidation calculations allow for easier retrieval of the design analyses that were completed for each weld overlay design. The weld overlays are demonstrated to be long-term repairs and/or mitigation of PWSCC in these welds based on the following:

In accordance with the Relief Requests, which are based on ASME Code Case N-504-2 and N-638-1, structural design of the overlays was performed to meet the requirements of ASME Code,Section XI, IWB-3640 based on an assumed flaw 100% through and 3600 around the original welds. The resulting full structural overlays thus restore the original safety margins of the original welds, with no credit taken for the underlying, PWSCC-susceptible material.

  • The weld metal used for the overlays is Alloy 52M, which has been shown to be resistant to PWSCC [10], thus providing a PWSCC resistant barrier.

Application of the weld overlays was shown to not impact the conclusions of the existing nozzle Stress Reports. Following application of the overlays, all ASME Code,Section III stress and fatigue criteria are met.

  • Nozzle specific residual stress analyses were performed, after first simulating severe ID weld repairs in the nozzle-to-safe end welds, prior to applying the weld overlays. The post weld overlay residual stresses were shown to result in beneficial compressive stresses on the inside surface of the components, and well into the thickness of the original DMWs, assuring that future PWSCC initiation or growth into the overlay is highly unlikely, or at worst, for certain cases, limited.

0800692.404, Rev. 1 9-1 Structural Integrity Associates, Inc.

9.0

SUMMARY

AND CONCLUSIONS This report provides a summary of the weld overlay design and analyses for the dissimilar metal welds in the Hot Leg Surge, Hot Leg Shutdown Cooling and Hot Leg Drain Nozzles at the San Onofre Nuclear Generating Station, Units 2 and 3. The design of these overlays was performed in accordance with requirements of the Relief Requests [2], which are based on ASME Code Case N-504-2 and N-638-1[1]. Consolidation calculations were completed for each weld overlay design (Appendix K for the Hot Leg Shutdown Cooling Nozzle, Appendix S for the Hot Leg Surge Nozzle (which includes Appendix T for additional analyses completed on the Unit 2 Hot Leg Surge Nozzle), and Appendix BB for the Hot Leg Drain Nozzle). These consolidation calculations allow for easier retrieval of the design analyses that were completed for each weld overlay design. The weld overlays are demonstrated to be long-term repairs and/or mitigation of PWSCC in these welds based on the following:

In accordance with the Relief Requests, which are based on ASME Code Case N-504-2 and N-638-1, structural design of the overlays was performed to meet the requirements of ASME Code,Section XI, IWB-3640 based on an assumed flaw 100% through and 360 0 around the original welds. The resulting full structural overlays thus restore the original safety margins of the original welds, with no credit taken for the underlying, PWSCC-susceptible material.

The weld metal used for the overlays is Alloy 52M, which has been shown to be resistant to PWSCC [10], thus providing a PWSCC resistant barrier.

Application of the weld overlays was shown to not impact the conclusions of the existing nozzle Stress Reports. Following application of the overlays, all ASME Code,Section III stress and fatigue criteria are met.

Nozzle specific residual stress analyses were performed, after first simulating severe ID weld repairs in the nozzle-to-safe end welds, prior to applying the weld overlays. The post weld overlay residual stresses were shown to result in beneficial compressive stresses on the inside surface of the components, and well into the thickness of the original DMWs, assuring that future PWSCC initiation or growth into the overlay is highly unlikely, or at worst, for certain cases, limited.

0800692.404, Rev. 1 9-1 fJ Structural Integrity Associates, Inc.

" Fracture mechanics analyses were performed to determine the amount of future crack growth which would be predicted in the DMW and stainless steel welds, assuming that cracks exist that are equal to or greater than the thresholds of the NDE techniques used. Both fatigue and PWSCC growth were considered, and found to be acceptable.

  • Axial shrinkage was measured following the overlay applications and was found to be small.

Therefore, shrinkage stresses at other locations in the piping systems arising from the weld overlays are not expected to have an adverse effect on the systems.

  • All hangers/supports that may be potentially affected were checked after the overlay repairs, and were found to be acceptable for continued operation.
  • The total added weight on the piping systems due to the overlays is relatively small compared to the weight of the piping systems, and therefore does not impact the stresses nor the dynamic characteristics of the piping systems.

" The as-built dimensions of the overlays meet the minimum and maximum design dimensions or are reconciled to those dimensions, thus demonstrating that the as-applied overlays satisfy the design requirements.

Based on the above observations and the fact that similar nozzle-to-safe end weld overlays have been applied to other plants since 1986 with no subsequent problems identified, it is concluded that the San Onofre Nuclear Generating Station, Units 2 and 3, Hot Leg Surge, Hot Leg Shutdown Cooling and Hot Leg Drain Nozzle dissimilar metal welds have received long term mitigation against PWSCC.

0800692.404, Rev. 1 9-2 1'ýStructural Integrity Associates, Inc.

Fracture mechanics analyses were performed to determine the amount of future crack growth which would be predicted in the DMW and stainless steel welds, assuming that cracks exist that are equal to or greater than the thresholds of the NDE techniques used. Both fatigue and PWSCC growth were considered, and found to be acceptable.

Axial shrinkage was measured following the overlay applications and was found to be small.

Therefore, shrinkage stresses at other locations in the piping systems arising from the weld overlays are not expected to have an adverse effect on the systems.

All hangers/supports that may be potentially affected were checked after the overlay repairs, and were found to be acceptable for continued operation.

The total added weight on the piping systems due to the overlays is relatively small compared to the weight of the piping systems, and therefore does not impact the stresses nor the dynamic characteristics of the piping systems.

The as-built dimensions of the overlays meet the minimum and maximum design dimensions or are reconciled to those dimensions, thus demonstrating that the as-applied overlays satisfy the design requirements.

Based on the above observations and the fact that similar nozzle-to-safe end weld overlays have been applied to other plants since 1986 with no subsequent problems identified, it is concluded that the San Onofre Nuclear Generating Station, Units 2 and 3, Hot Leg Surge, Hot Leg Shutdown Cooling and Hot Leg Drain Nozzle dissimilar metal welds have received long term mitigation against PWSCC.

0800692.404, Rev. 1 9-2 I) Structural Integrity Associates, Inc.

10.0 REFERENCES

1.

ASME Code Cases:

A.

ASME Boiler and Pressure Vessel Code, Code Case N-504-2, "Alternative Rules for Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping,Section XI, Division 1."

B.

ASME Boiler and Pressure Vessel Code, Code Case N-638-1, " Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,Section XI, Division 1

2.

San Onofre Specification S023-923-01, Rev. 1, Conformed Specification for Design and Implementation of Hot Leg Nozzles Weld Overlay Repair, SI File No. 0800692.202P:

A.

Enclosure to Appendix 3A: Safety Evaluation by the Office of Nuclear Reactor Regulation Relief Request ISI-3-27 and ISI-3-28 Full Structural Weld Overlay and Alternative Repair Techniques Southern California Edison B.

Southern California Edison, San Onofre Nuclear Generating Station, Units 2 and 3, Docket No. 50-361 and 50-362, Revision 1 to Relief Request ISI-3-27, "Use of Structural Weld Overlay and Associated Alternative Repair Techniques" C.

Southern California Edison, San Onofre Nuclear Generating Station, Units 2 and 3, Docket No. 50-361 and 50-362, Revision 1 to Relief Request ISI-3-28, "48-Hour Hold Period Following Application of the Third Temperbead Layer"

3.

ASME Boiler and Pressure Vessel Code,Section XI, 1995 Edition with Addenda through 1996.

4.

pc-CRACK for Windows, Version 3.1-98348, Structural Integrity Associates, 1998.

5.

Rybicki, E. F., et al., "Residual Stresses at Girth-Butt Welds in Pipes and Pressure Vessels," U.S. Nuclear Regulatory Commission Report NUREG-0376, R5, November 1977.

6.

Rybicki, E. F., and Stonesifer, R. B., "Computation of Residual Stresses Due to Multipass Welds in Piping Systems," Journal of Pressure Vessel Technology, Vol.

101, May 1979.

7.

Journal of Pressure Vessel Technology: "Residual Stress Analysis of a Multi-Pass Girth Weld: 3-D Special Shell Versus Axisymmetric Models," May 2001, Vol. 123.

8.

"Materials Reliability Program: Technical Basis for Preemptive Weld Overlays for Alloy 82/182 Butt Welds in PWRs (MRP-169)," EPRI, Palo Alto, CA, and Structural Integrity Associates, Inc., San Jose, CA: 2005, 1012843.

9.

ANSYS Release 8.1 (with Service Pack 1), ANSYS, Inc., June 2004.

006244 Structural Integrity Associates, Inc.

10.0 REFERENCES

1.

ASME Code Cases:

A.

ASME Boiler and Pressure Vessel Code, Code Case N-504-2, "Alternative Rules for Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping,Section XI, Division 1."

B.

ASME Boiler and Pressure Vessel Code, Code Case N-638-1, " Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,Section XI, Division 1

2.

San Onofre Specification S023-923-01, Rev. 1, Conformed Specification for Design and Implementation of Hot Leg Nozzles Weld Overlay Repair, SI File No. 0800692.202P:

A.

Enclosure to Appendix 3A: Safety Evaluation by the Office of Nuclear Reactor Regulation Relief Request ISI-3-27 and ISI-3-28 Full Structural Weld Overlay and Alternative Repair Techniques Southern California Edison B.

Southern California Edison, San Onofre Nuclear Generating Station, Units 2 and 3, Docket No. 50-361 and 50-362, Revision 1 to Relief Request ISI-3-27, "Use of Structural Weld Overlay and Associated Alternative Repair Techniques" C.

Southern California Edison, San Onofre Nuclear Generating Station, Units 2 and 3, Docket No. 50-361 and 50-362, Revision 1 to Relief Request ISI-3-28, "48-Hour Hold Period Following Application of the Third Temperbead Layer" 3.'

ASME Boiler and Pressure Vessel Code,Section XI, 1995 Edition with Addenda through 1996.

4.

pc-CRACK for Windows, Version 3.1-98348, Structural Integrity Associates, 1998.

5.

Rybicki, E. F., et aI., "Residual Stresses at Girth-Butt Welds in Pipes and Pressure Vessels," U.S. Nuclear Regulatory Commission Report NUREG-0376, R5, November 1977.

6.

Rybicki, E. F., and Stonesifer, R. B., "Computation of Residual Stresses Due to Multipass Welds in Piping Systems," Journal of Pressure Vessel Technology, Vol.

101, May 1979.

7.

Journal of Pressure Vessel Technology: "Residual Stress Analysis ofa Multi-Pass Girth Weld: 3-D Special Shell Versus Axisymmetric Models," May 2001, Vol. 123.

8.

"Materials Reliability Program: Technical Basis for Preemptive Weld Overlays for Alloy 821182 Butt Welds in PWRs (MRP-169)," EPR!, Palo Alto, CA, and Structural Integrity Associates, Inc., San Jose, CA: 2005, 1012843.

9.

ANSYS Release 8.1 (with Service Pack 1), ANSYS, Inc., June 2004.

0800692.404, Rev. I lO-l l) Slruclurallnlegrily Associates, Inc.

10.

"Materials Reliability Program (MRP): Resistance to Primary Water Stress Corrosion Cracking of Alloys 690, 52, and 152 in Pressurized Water Reactors (MRP-1 11)," EPRI, Palo Alto, CA: 2004, 1009801.

11.

"Materials Reliability Program: Crack Growth Rates for Evaluating Primary Water Stress Corrosion Cracking (PWSCC) of Alloy 82, 182, and 132 Welds (MRP-115)," EPRI, Palo Alto, CA: 2004, 1006696.

12.

NUREG/CR-6907, "Crack Growth Rates of Nickel Alloy Welds in a PWR Environment," U.S. Nuclear Regulatory Commission (Argonne National Laboratory),

May 2006.

13.

NUREG/CR-6721, "Effects of Alloy Chemistry, Cold Work, and Water Chemistry on Corrosion Fatigue and Stress Corrosion Cracking of Nickel Alloys and Welds," U.S.

Nuclear Regulatory Commission (Argonne National Laboratory), 2001.

14.

ASME Boiler and Pressure Vessel Code,Section III, 1998 Edition with Addenda through 2000.

15.

WSI Drawing No. 406956, Rev. 1, "Construction Drawing Hot Leg SDC, SONGS Unit 2, 3," SI File No. 0800692.215.

16.

WSI Drawing No. 406955, Rev. 2, "Construction Drawing Hot Leg Surge, SONGS Unit 3," SI File No. 0800692.215.

17.

WSJ Drawing No. 406957, Rev. 1, "Construction Drawing Hot Leg Drain, SONGS Unit 2, 3," SI File No. 0800692.215.

18.

WSJ Drawing No. 408143, Rev. 0, "Construction Drawing Hot Leg SDC, SONGS Unit 2," SI File No. 0800692.221.

19.

WSI Drawing No. 408142, Rev. 3, "Construction Drawing Hot Leg Surge, SONGS Unit 2," SI File No. 0800692.221.

20.

WSI Drawing No. 408144, Rev. 0, "Construction Drawing Hot Leg Drain, SONGS Unit 2," SI File No. 0800692.221.

21.

E-mail from Jose Oikawa to Jim Axline, April 14, 2009,

Subject:

RE: Draft Rev A Thermal Mechanical & Residual Stress Calculations Unit 3 Surge WOL 0800692.343 and 0800692.344, SI File No, 0800692.222

22.

WSI NCR No.08-223 to Traveler 104534-TR-017, Rev. 0, SI File No. 0800692.223.

23.

WSI NCR No.09-281 to Traveler 104534-TR-007, Rev. 0, SI File No. 0800692.223.

24.

WSI NCR No.09-282 to Traveler 104534-TR-017, Rev. 0, SI File No. 0800692.223.

0800692.404, Rev. 1 10-2 Structural Integrity Associates, Inc.

10.

"Materials Reliability Program (MRP): Resistance to Primary Water Stress Corrosion Cracking of Alloys 690,52, and 152 in Pressurized Water Reactors (MRP-111)," EPR!,

Palo Alto, CA: 2004, 1009801.

11.

"Materials Reliability Program: Crack Growth Rates for Evaluating Primary Water Stress Corrosion Cracking (PWSCC) of Alloy 82, 182, and 132 Welds (MRP-115)," EPR!, Palo Alto, CA: 2004, 1006696.

12.

NUREG/CR-6907, "Crack Growth Rates of Nickel Alloy Welds in a PWR Environment," u.s. Nuclear Regulatory Commission (Argonne National Laboratory),

May 2006.

13.

NUREG/CR-6721, "Effects of Alloy Chemistry, Cold Work, and Water Chemistry on Corrosion Fatigue and Stress Corrosion Cracking of Nickel Alloys and Welds," u.S.

Nuclear Regulatory Commission (Argonne National Laboratory), 2001.

14.

ASME Boiler and Pressure Vessel Code,Section III, 1998 Edition with Addenda through 2000.

15.

WSI Drawing No. 406956, Rev. 1, "Construction Drawing Hot Leg SDC, SONGS Unit 2,3," SI File No. 0800692.215.

16.

WSI Drawing No. 406955, Rev. 2, "Construction Drawing Hot Leg Surge, SONGS Unit 3," SI File No. 0800692.215.

17.

WSI Drawing No. 406957, Rev. 1, "Construction Drawing Hot Leg Drain, SONGS Unit 2,3," SI File No. 0800692.215.

18.

WSI Drawing No. 408143, Rev. 0, "Construction Drawing Hot Leg SDC, SONGS Unit 2," SI File No. 0800692.221.

19.

WSI Drawing No. 408142, Rev. 3, "Construction Drawing Hot Leg Surge, SONGS Unit 2," SI File No. 0800692.221.

20.

WSI Drawing No. 408144, Rev. 0, "Construction Drawing Hot Leg Drain, SONGS Unit 2," SI File No. 0800692.221.

21.

E-mail from Jose Oikawa to Jim Axline, April 14, 2009,

Subject:

RE: Draft Rev A Thermal Mechanical & Residual Str~ss Calculations Unit 3 Surge WOL 0800692.343 and 0800692.344, SI File No, 0800692.222

22.

WSI NCR No.08-223 to Traveler 104534-TR-017, Rev. 0, SI File No. 0800692.223.

23.

WSI NCR No.09-281 to Traveler 104534-TR-007, Rev. 0, SI File No. 0800692.223.

24.

WSI NCR No.09-282 to Traveler 104534-TR-017, Rev. 0, SI File No. 0800692.223.

0800692.404, Rev. 1 10-2 I) Structural Integrity Associates, Inc.

11.0 APPENDICES - STRUCTURAL INTEGRITY ASSOCIATES CALCULATION PACKAGES AND DESIGN DRAWINGS1 Appendix A

B C

D E

F G

H K

L M

N 0

P Q

R S

Document No 0800692.301 0800692.302 0800692.303 0800692.310 0800692.311 0800692.312 0800692.313 0800692.314 0800692.315 0800692.316 0800692.317 0800692.320 0800692.321 0800692.322 0800692.323 0800692.324 0800692.325 0800692.326 0800692.327 Description Material Properties for the Finite Element Analyses of Dissimilar Metal Overlays Weld Overlay Design Weight Calculation Hot Leg Surge Nozzle Weld Overlay Shrinkage Analysis Weld Overlay Sizing for Hot Leg Shutdown Cooling Nozzle Design Loads for Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair Finite Element Model of Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair Thermal and Mechanical Stress Analyses of Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair Residual Stress Analysis of Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair ASME Code,Section III Evaluation of Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair Crack Growth Evaluation of Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair Consolidation Calculation for Hot Leg Shutdown Cooling Nozzle Weld Overlay Repair Weld Overlay Sizing for Hot Leg Surge Nozzle Design Loads for Hot Leg Surge Nozzle With Weld Overlay Repair Finite Element Model of Hot Leg Surge Nozzle with Weld Overlay Repair Thermal and Mechanical Stress Analyses of Hot Leg Surge Nozzle with Weld Overlay Repair Residual Stress Analysis of Hot Leg Surge Nozzle with Weld Overlay Repair ASME Code,Section III Evaluation of the Hot Leg Surge Nozzle with Weld Overlay Repair Crack Growth Evaluation of Hot Leg Surge Nozzle with Weld Overlay Repair Consolidation Calculation for Hot Leg Surge Nozzle Weld Overlay Repair 11-1 V

Structural Integrity Associates, Inc.

0800692.404, Rev. 1 11.0 APPENDICES - STRUCTURAL INTEGRITY ASSOCIATES CALCULATION PACKAGES AND DESIGN DRAWINGS1 Am~endix Document No Description A

0800692.301 Material Properties for the Finite Element Analyses of Dissimilar Metal Overlays B

0800692.302 Weld Overlay Design Weight Calculation C

0800692.303 Hot Leg Surge Nozzle Weld Overlay Shrinkage Analysis D

0800692.310 Weld Overlay Sizing for Hot Leg Shutdown Cooling Nozzle E

0800692.311 Design Loads for Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair F

0800692.312 Finite Element Model of Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair G

0800692.313 Thermal and Mechanical Stress Analyses of Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair H

0800692.314 Residual Stress Analysis of Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair I

0800692.315 ASME Code,Section III Evaluation of Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair J

0800692.316 Crack Growth Evaluation of Hot Leg Shutdown Cooling Nozzle with Weld Overlay Repair K

0800692.317 Consolidation Calculation for Hot Leg Shutdown Cooling Nozzle Weld Overlay Repair L

0800692.320 Weld Overlay Sizing for Hot Leg Surge Nozzle M

0800692.321 Design Loads for Hot Leg Surge Nozzle With Weld Overlay Repair N

0800692.322 Finite Element Model of Hot Leg Surge Nozzle with Weld Overlay Repair 0

0800692.323 Thermal and Mechanical Stress Analyses of Hot Leg Surge Nozzle with Weld Overlay Repair P

0800692.324 Residual Stress Analysis of Hot Leg Surge Nozzle with Weld Overlay Repair Q

0800692.325 ASME Code,Section III Evaluation of the Hot Leg Surge Nozzle with Weld Overlay Repair R

0800692.326 Crack Growth Evaluation of Hot Leg Surge Nozzle with Weld Overlay Repair S

0800692.327 Consolidation Calculation for Hot Leg Surge Nozzle Weld Overlay Repair 0800692.404, Rev. 1 11-1 lJ Structural Integrity Associates, Inc.

T U

V w

x Y

z AA BB cc DD EE FF GG HH II JJ 0800692.328 0800692.330 0800692.331 0800692.332 0800692.333 0800692.334 0800692.335 0800692.336 0800692.337 0800692.342 0800692.343 0800692.344 0800692.345 0800692.346 0800692.510 0800692.520 0800692.530 Reconciliation for Modified Unit 2 Hot Leg Surge Nozzle Weld Overlay Repair Weld Overlay Sizing for Hot Leg Drain Nozzle Design Loads for Hot Leg Drain Nozzle with WOL Finite Element Models of Hot Leg Drain Nozzle with Weld Overlay Repair Thermal and Mechanical Stress Analyses of Hot Leg Drain Nozzle with Weld Overlay Repair Residual Stress Analysis of Hot Leg Drain Nozzle with Weld Overlay Repair ASME Code,Section III Evaluation of Hot Leg Drain Nozzle with Weld Overlay Repair Crack Growth Evaluation of Hot Leg Drain Nozzle with Weld Overlay Repair Consolidation Calculation for Hot Leg Drain Nozzle Weld Overlay Repair Finite Element Models of Unit 3 Hot Leg Surge Nozzle with Weld Overlay Repair Thermal and Mechanical Stress Analyses of Unit 3 Hot Leg Surge Nozzle with Weld Overlay Repair Residual Stress Analysis of Unit 3 Hot Leg Surge Nozzle with Weld Overlay Repair ASME Code,Section III Evaluation of Unit 3 Hot Leg Surge Nozzle with Weld Overlay Repair Crack Growth Evaluation of Unit 3 Hot Leg Surge Nozzle with Weld Overlay Repair Design Drawing Hot Leg SDC, SONGS Unit 2, 3 (SI Drawing No. 0800692.5 10)

Design Drawing Hot Leg Surge, SONGS Unit 2, 3 (SI Drawing No. 0800692.520)

Design Drawing Hot Leg Drain, SONGS Unit 2, 3 (SI Drawing No. 0800692.530)

IFor the revision number of the document, refer to the SI Project Revision Log, latest revision.

The appendices are contained in separate individual calculation packages and transmitted separately from this report.

Structural Integrity Associates, Inc.

T 0800692.328 Reconciliation for Modified Unit 2 Hot Leg Surge Nozzle Weld Overlay Repair U

0800692.330 Weld Overlay Sizing for Hot Leg Drain Nozzle V

0800692.331 Design Loads for Hot Leg Drain Nozzle with WOL W

0800692.332 Finite Element Models of Hot Leg Drain Nozzle with Weld Overlay Repair X

0800692.333 Thermal and Mechanical Stress Analyses of Hot Leg Drain Nozzle with Weld Overlay Repair y

0800692.334 Residual Stress Analysis of Hot Leg Drain Nozzle with Weld Overlay Repair Z

0800692.335 ASME Code,Section III Evaluation of Hot Leg Drain Nozzle with Weld Overlay Repair AA 0800692.336 Crack Growth Evaluation of Hot Leg Drain Nozzle with Weld Overlay Repair BB 0800692.337 Consolidation Calculation for Hot Leg Drain Nozzle Weld Overlay Repair CC 0800692.342 Finite Element Models of Unit 3 Hot Leg Surge Nozzle with Weld Overlay Repair DD 0800692.343 Thermal and Mechanical Stress Analyses of Unit 3 Hot Leg Surge Nozzle with Weld Overlay Repair EE 0800692.344 Residual Stress Analysis of Unit 3 Hot Leg Surge Nozzle with Weld Overlay Repair FF 0800692.345 ASME Code,Section III Evaluation of Unit 3 Hot Leg Surge Nozzle with Weld Overlay Repair GG 0800692.346 Crack Growth Evaluation of Unit 3 Hot Leg Surge Nozzle with Weld Overlay Repair HH 0800692.510 Design Drawing Hot Leg SDC, SONGS Unit 2, 3 (SI Drawing No. 0800692.510)

II 0800692.520 Design Drawing Hot Leg Surge, SONGS Unit 2, 3 (SI Drawing No. 0800692.520)

JJ 0800692.530 Design Drawing Hot Leg Drain, SONGS Unit 2, 3 (SI Drawing No. 0800692.530)

IFor the revision number of the document, refer to the SI Project Revision Log, latest revision.

The appendices are contained in separate individual calculation packages and transmitted separately from this report.

0800692.404, Rev. 1 11-2 l) Structural Integrity Associates, Inc.

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