ML17152A305

N-16D Nozzle Repair - Submittal of Analytical Flaw Evaluation, Design Analysis, and Corrosion Evaluation (Rev. 1)

ML17152A305
Person / Time
Site:	Limerick
Issue date:	06/01/2017
From:	David Helker Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML17152A304	List: ML17152A305
References
CAC MF9702, LG-17-081 32-9271581-000
Download: ML17152A305 (97)

Text

PROPRIETARY INFORMATION-WITHHOLD UNDER 10 CFR 2.390 Attachments 1, 2, and 3 contain proprietary information - the balance of this letter is x e n en era *I0 n considered non-proprietary when Attachments 1, 2, and 3 are removed.

200 Exelon Way E l G 0 t @ Kennett Square, PA 19348 www.exeloncorp.com 10 CFR 50.55a LG-17-081 June 1, 2017 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Unit 2 Renewed Facility Operating License No. NPF-85 NRC Docket No. 50-353

Subject:

Limerick Generating Station, Unit 2 N-16D Nozzle Repair - Submittal of Analytical Flaw Evaluation, Design Analysis, and Corrosion Evaluation (Rev. 1)

References:

1. Letter from D. P. Helker (Exelon Generating Company, LLC) to U.S.

Nuclear Regulatory Commission, "Proposed Relief Request Associated with Reactor Pressure Vessel Nozzle Repairs," dated May 15, 2017 (ML17135A423)

2. Email from V. Sreenivas (U.S. Nuclear Regulatory Commission) to T. Loomis (Exelon Generating Company, LLC), "Limerick-Unit 2: Request for Additional Information for Relief Request Associated with Reactor Pressure Vessel Nozzle Repairs (CAC No. MF9702)," dated May 16, 2017 (ML17137A165)

3. Letter from D. P. Helker (Exelon Generating Company, LLC) to U.S.

Nuclear Regulatory Commission, "Proposed Relief Request Associated with Reactor Pressure Vessel Nozzle Repairs," dated May 16, 2017 (Ml 17137A068)

4. "Summary of May 17, 2017, Telephone Conference Regarding Verbal Authorization of Relief Request for Limerick Generating Station, Unit 2 (CAC No. MF9702)," dated May 17, 2017 (ML17137A277)

In Reference 1, in accordance with 10 CFR 50.55a, Exelon Generation Company, LLC (EGC) requested approval of a relief request associated with the repair of a 2-inch instrument line nozzle at penetration N-16D on the Reactor Pressure Vessel (RPV). On May 16, 2017 (Reference 2), the U.S. Nuclear Regulatory Commission (USNRC) requested additional information. This information was supplied in Reference 3. Reference 4 documents the verbal authorization of the repair.

PROPRIETARY INFORMATION -WITHHOLD UNDER 10 CFR 2.390 Attachments 1, 2, and 3 contain proprietary information - the balance of this letter is considered non-proprietary when Attachments 1, 2, and 3 are removed.

Limerick Generating Station, Unit 2 N-16D Nozzle Repair - Submittal of Analytical Flaw Evaluation, Design Analysis, and Corrosion Evaluation (Rev. 1)

June 1, 2017 Page2 As discussed in Reference 3, EGG committed to supplying the analytical flaw evaluation and design analysis. Attached are these analyses and an updated corrosion evaluation that was submitted in the Reference 3 letter.

Attachments 1 ("Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification," Document Number 32-9271581-000); 2 ("Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification," Document Number 32-9271575-000); and 3

("Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification,"

Document Number 51-9271544-001) contain information proprietary to AREVA Inc.

(AREVA). AREVA requests that the document be withheld from public disclosure in accordance with 10 CFR 2.390(a)(4). Affidavits supporting this request are contained in Attachments 4, 5, and 6. Attachments 7, 8, and 9 contain non-proprietary versions of the AREVA documents.

If you have any questions or require additional information, please contact Tom Loomis at 610-765-5510.

Sincerely, David P. Helker Manager - Licensing and Regulatory Affairs Exelon Generation Company, LLC Attachments: 1) "limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification," Document Number 32-9271581-000 (Proprietary Version)

2) "Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification,"

Document Number 32-9271575-000 (Proprietary Version)

3) "Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification," Document Number 51-9271544-001 (Proprietary Version)

4) Affidavit Associated with "Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification," Document Number 32-9271581-000

5) Affidavit Associated with "Limerick Unit 2 Instrumentation Nozzle Repair -

One Cycle Justification," Document Number 32-9271575-000

6) Affidavit Associated with "Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification," Document Number 51-9271544-001

Limerick Generating Station, Unit 2 N-16D Nozzle Repair - Submittal of Analytical Flaw Evaluation, Design Analysis, and Corrosion Evaluation (Rev. 1)

June 1, 2017 Page 3

7) "Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)," Document Number 32-9272082-000

8) "Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)," Document Number 32-9272081-000

9) "Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)," Document Number 51-9271770-001 cc: USNRC Region I, Regional Administrator USNRC Senior Resident Inspector, LGS USNRC Project Manager, LGS R. R. Janati, Pennsylvania Bureau of Radiation Protection -

(w/o Attachments 1, 2, and 3)

Attachment 4 Affidavit Associated with "Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification," Document Number 32-9271581-000

AFFIDAVIT COMMONWEALTH OF VIRGINIA SS.

CITY OF LYNCHBURG

1. My name is Gayle Elliott. I am Deputy Director, Licensing & Regulatory Affairs, for AREVA Inc. (AREVA) and as such I am authorized to execute this Affidavit.

2. I am familiar with the criteria applied by AREVA to determine whether certain AREVA information is proprietary. I am familiar with the policies established by AREVA to ensure the proper application of these criteria.

3. I am familiar with the AREVA information contained in Calculation Summary Sheet (CSS) No. 32-9271581-000, entitled, "Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification," and referred to herein as "Document." Information contained in this Document has been classified by AREVA as proprietary in full in accordance with the policies established by AREVA Inc. for the control and protection of proprietary and confidential information.

4. This Document contains information of a proprietary and confidential nature and is of the type customarily held in confidence by AREVA and not made available to the public. Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.

5. This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in accordance with 10 CFR 2.390. The information for which withholding from disclosure is

requested qualifies under 10 CFR 2.390(a)(4) "Trade secrets and commercial or financial information."

6. The following criteria are customarily applied by AREVA to determine whether information should be classified as proprietary:

(a) The information reveals details of AREVA's research and development plans and programs or their results.

(b) Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, in time or resources, to design, produce, or market a similar product or service.

(c) The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for AREVA.

(d) The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for AREVA in product optimization or marketability.

(e) The information is vital to a competitive advantage held by AREVA, would be helpful to competitors to AREVA, and would likely cause substantial harm to the competitive position of AREVA.

The information in this Document is considered proprietary for the reasons set forth in paragraphs 6(c), 6(d) and 6(e) above.

7. In accordance with AREVA's policies governing the protection and control of information, proprietary information contained in this Document has been made available, on a limited basis, to others outside AREVA only as required and under suitable agreement providing for nondisclosure and limited use of the information ..

8. AREVA policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.

9. The foregoing statements are true and correct to the best of my knowledge, information, and belief.

SUBSCRIBED before me this day of __ ~---~-----' 2017.

Sherry L. McFaden NOTARY PUBLIC, COMMONWEALTH OF VIRGINIA MY COMMISSION EXPIRES: 10/31/18 Reg.# 7079129

Attachment 5 Affidavit Associated with "Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification," Document Number 32-9271575-000

AFFIDAVIT COMMONWEALTH OF VIRGINIA SS.

CITY OF LYNCHBURG

1. My name is Gayle Elliott. I am Deputy Director, Licensing & Regulatory Affairs, for AREVA Inc. (AREVA) and as such I am authorized to execute this Affidavit.

2. I am familiar with the criteria applied by AREVA to determine whether certain AREVA information is proprietary. I am familiar with the policies established by AREVA to ensure the proper application of these criteria.

3. I am familiar with the AREVA information contained in Calculation Summary Sheet (CSS) No. 32-9271575-000, entitled, "Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification," and referred to herein as "Document." Information contained in this Document has been classified by AREVA as proprietary in full in accordance with the policies established by AREVA Inc. for the control and protection of proprietary and confidential information.

4. This Document contains information of a proprietary and confidential nature and is of the type customarily held in confidence by AREVA and not made available to the public. Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.

5. This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in accordance with 10 CFR 2.390. The information for which withholding from disclosure is

requested qualifies under 10 CFR 2.390(a)(4) "Trade secrets and commercial or financial information."

6. The following criteria are customarily applied by AREVA to determine whether information should be classified as proprietary:

(a) The information reveals details of AREVA's research and development plans and programs or their results.

(b) Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, in time or resources, to design, produce, or market a similar product or service.

(c) The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for AREVA.

(d) The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for AREVA in product optimization or marketability.

(e) The information is vital to a competitive advantage held by AREVA, would be helpful to competitors to AREVA, and would likely cause substantial harm to the competitive position of AREVA.

The information in this Document is considered proprietary for the reasons set forth in paragraphs 6(c), 6(d) and 6(e) above.

7. In accordance with AREVA's policies governing the protection and control of information, proprietary information contained in this Document has been made available, on a limited basis, to others outside AREVA only as required and under suitable agreement providing for nondisclosure and limited use of the information.

8. AREVA policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.

9. The foregoing statements are true and correct to the best of my knowledge, information, and belief.

SUBSCRIBED before me this day of YV\Jvv( '2017.

Sherry L. Mcfaden NOTARY PUBLIC, COMMONWEALTH OF VIRGINIA MY COMMISSION EXPIRES: 10/31/18 Reg.# 7079129

Attachment 6 Affidavit Associated with "Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification," Document Number 51-9271544-001

AFFIDAVIT COMMONWEALTH OF VIRGINIA )

) SS.

CITY OF LYNCHBURG )

1. My name is Tom Ryan. I am Manager, Product Licensing, for AREVA Inc.

(AREVA) and as such I am authorized to execute this Affidavit.

2. I am familiar with the criteria applied by AREVA to determine whether certain AREVA information is proprietary. I am familiar with the policies established by AREVA to ensure the proper application of these criteria.

3. I am familiar with the AREVA information contained in the AREVA document "51-9271544-001, Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification", and referred to herein as "Document." Information contained in this Document has been classified by AREVA as proprietary in accordance with the policies established by AREVA Inc. for the control and protection of proprietary and confidential information.

4. This Document contains information of a proprietary and confidential nature and is of the type customarily held in confidence by AREVA and not made available to the public.

Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.

5. This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in

accordance with 10 CFR 2.390. The information for which withholding from disclosure is requested qualifies under 10 CFR 2.390(a)(4) "Trade secrets and commercial or financial information."

6. The following criteria are customarily applied by AREVA to determine whether information should be classified as proprietary:

(a) The information reveals details of AREVA's research and development plans and programs or their results.

(b) Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, in time or resources, to design, produce, or market a similar product or service.

(c) The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for AREVA.

(d) The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for AREVA in product optimization or marketability.

(e) The information is vital to a competitive advantage held by AREVA, would be helpful to competitors to AREVA, and would likely cause substantial harm to the competitive position of AREVA The information in this Document is considered proprietary for the reasons set forth in paragraphs 6(a), 6(c) and 6(d) above.

7. In accordance with AREVA's policies governing the protection and control of information, proprietary information contained in this Document has been made available, on a limited basis, to others outside AREVA only as required and under suitable agreement providing for nondisclosure and limited use of the information.

8. AREVA policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.

9. The foregoing statements are true and correct to the best of my knowledge, information, and belief.

SUBSCRIBED before me this

-Pbt:!:i day of YV'WAJY J 2017.

Sherry L. McFaden NOTARY PUBLIC, COMMONWEALTH OF VIRGINIA MY COMMISSION EXPIRES: 10/31/18 Reg.# 7079129 SHERRY L. MCFADEN NDJary Public Commonwealth or Vtrglnf a 7079129 M comm111lon Eaplres Oct 31, 2018

Attachment 7 "Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)," Document Number 32-9272082-000

Controlled Document 0402-01-F01 (Rev. 020, 11/17/2016)

CALCULATION

SUMMARY

SHEET (CSS)

Document No. 32 - 9272082 - 000 Safety Related: Yes No Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification Title (Non-Proprietary)

PURPOSE AND

SUMMARY

OF RESULTS:

PURPOSE:

During the Spring 2017 outage, leakage was discovered at Reactor Pressure Vessel (RPV) Instrument Nozzle 16D, which is a radial nozzle extending horizontally from the cylindrical vessel shell. Per Reference [1], the leakage is identified to be at approximately the 1 oclock position. The cause of the leakage has not been determined. However, based on industry experience, the most likely cause is intergranular stress corrosion cracking (IGSCC) either through the Alloy 182 J-Groove weld or through the Alloy 600 nozzle. A half nozzle repair was designed in which the existing nozzle will be severed and a replacement nozzle will be attached to the OD of the reactor pressure vessel (References [2] and [3]). The present concern is that a flaw in the remnant J-Groove weld could impact the structural integrity of the vessel. Flaws in the nozzle material will not propagate into the vessel material. However, a flaw in the weld metal may propagate into the low alloy steel. Since the hoop stress in the vessel at the J-groove weld is greater than the axial stress at the same location, the preferential direction for cracking is radial relative to the nozzle and axial relative to the vessel. Therefore, a radial-axial flaw is postulated to extend through the entire J-Groove weld and buttering. The purpose of this analysis is to evaluate the postulated radial-axial flaw for one fuel cycle of operation.

SUMMARY

OF RESULTS:

Based on a combination of Linear Elastic Fracture Mechanics (IWB-3610 of ASME Section XI, Reference [6]) and Elastic Plastic Fracture Mechanics (ASME Code Case N-749, Reference [7]), the postulated flaw in the as-left J-groove weld of nozzle 16D at Limerick Unit 2 is shown to be acceptable for one fuel cycle following the Spring 2017 outage. Results are summarized in Section 7.0.

Note: Proprietary information in this document is indicated by bolded brackets ([ ]).

If the computer software used herein is not the latest version per the EASI list, THE DOCUMENT CONTAINS AP 0402-01 requires that justification be provided.

ASSUMPTIONS THAT SHALL BE THE FOLLOWING COMPUTER CODES HAVE BEEN USED IN THIS DOCUMENT: VERIFIED PRIOR TO USE CODE/VERSION/REV CODE/VERSION/REV Yes ANSYS 16.0 No Page 1 of 47

Controlled Document 0402-01-F01 (Rev. 020, 11/17/2016)

Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Review Method: Design Review (Detailed Check)

Alternate Calculation Does this document establish design or technical requirements? YES NO Does this document contain Customer Required Format? YES NO Signature Block P/R/A/M Name and Title and Pages/Sections (printed or typed) Signature LP/LR Date Prepared/Reviewed/Approved Tom Riordan TE RIORDAN LP All except Appendix A Engineer IV 5/20/2017 Martin Kolar M KOLAR P Appendix A Principal Engineer 5/20/2017 Silvester Noronha SJ NORONHA LR All except Appendix A Principal Engineer 5/20/2017 Jarrett Somers JM SOMERS R Appendix A Principal Engineer 5/20/2017 David Cofflin DR COFFLIN A All Engineering Manager 5/20/2017 Notes: P/R/A designates Preparer (P), Reviewer (R), Approver (A);

LP/LR designates Lead Preparer (LP), Lead Reviewer (LR);

M designates Mentor (M)

In preparing, reviewing and approving revisions, the lead preparer/reviewer/approver shall use All or All except

___ in the pages/sections reviewed/approved. All or All except ___ means that the changes and the effect of the changes on the entire document have been prepared/reviewed/approved. It does not mean that the lead preparer/reviewer/approver has prepared/reviewed/approved all the pages of the document.

Page 2

Controlled Document 0402-01-F01 (Rev. 020, 11/17/2016)

Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Signature Block (Continued)

Project Manager Approval of Customer References and/or Customer Formatting (N/A if not applicable)

Name Title (printed or typed) (printed or typed) Signature Date Dave Skulina Project Manager DJ SKULINA 5/20/2017 Page 3

Controlled Document 0402-01-F01 (Rev. 020, 11/17/2016)

Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Record of Revision Revision Pages/Sections/Paragraphs No. Changed Brief Description / Change Authorization 000 All Original release; Note proprietary version is 32-9271581-000.

Page 4

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Table of Contents Page SIGNATURE BLOCK ................................................................................................................................ 2 RECORD OF REVISION .......................................................................................................................... 4 LIST OF TABLES ..................................................................................................................................... 7 LIST OF FIGURES ................................................................................................................................... 8 1.0 PURPOSE ..................................................................................................................................... 9 2.0 ANALYTICAL METHODOLOGY ................................................................................................... 9 2.1 Stress Intensity Factor Solution ...................................................................................................... 10 2.2 Linear Elastic Fracture Mechanics .................................................................................................. 14 2.3 Elastic Plastic Fracture Mechanics ................................................................................................. 14 2.3.1 Screening Criteria ............................................................................................................. 14 2.3.2 Acceptance Criteria ..........................................................................................................14 2.4 Primary Stress Evaluation ............................................................................................................... 15 3.0 ASSUMPTIONS .......................................................................................................................... 16 3.1 Unverified Assumptions................................................................................................................... 16 3.2 Justified Assumptions...................................................................................................................... 16 3.3 Modeling Simplifications .................................................................................................................. 16 4.0 DESIGN INPUTS ........................................................................................................................ 17 4.1 Geometry ......................................................................................................................................... 17 4.2 Materials .......................................................................................................................................... 17 4.2.1 Mechanical Properties ...................................................................................................... 18 4.2.2 Fracture Material Properties ............................................................................................. 18 4.3 Applied Stresses ............................................................................................................................. 19 4.3.1 Operating Stresses ...........................................................................................................19 4.3.2 Weld Residual Stress ....................................................................................................... 19 4.3.3 Crack Face Pressure ........................................................................................................ 20 5.0 COMPUTER USAGE .................................................................................................................. 20 5.1 Computer Software ......................................................................................................................... 20 5.2 Computer Files ................................................................................................................................ 20 6.0 CALCULATIONS ......................................................................................................................... 21 6.1 LEFM Evaluation ............................................................................................................................. 21 6.2 EPFM Evaluation............................................................................................................................. 24 6.3 Primary Stress Evaluation ............................................................................................................... 26 Page 5

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Table of Contents (continued)

Page

7.0 CONCLUSION

S .......................................................................................................................... 27

8.0 REFERENCES

............................................................................................................................ 28 APPENDIX A : OPERATING STRESS ANALYSIS............................................................................... 29 APPENDIX B : SIF SOLUTION TEST CASES ..................................................................................... 46 Page 6

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

List of Tables Page Table 2-1: EPFM Structural Factors ...................................................................................................... 14 Table 4-1: Key Dimensions .................................................................................................................... 17 Table 5-1: Computer Files ..................................................................................................................... 20 Table 6-1: LEFM Results ....................................................................................................................... 22 Table 6-2: EPFM Results ....................................................................................................................... 25 Table A-1: Material Designations ............................................................................................................ 30 Table A-2: Heat Up and Cool Down....................................................................................................... 32 Table A-3: SCRAM ................................................................................................................................ 33 Table A-4: SCRAM + Blowdown ............................................................................................................ 34 Table A-5: Blowdown ............................................................................................................................. 35 Table A-6: Time Points Selection for Stress Runs .................................................................................. 38 Table A-7: Stress Origin Description...................................................................................................... 39 Table A-8: Column Description .............................................................................................................. 40 Table A-9: Heat Up / Cool Down Thermal + Pressure Stresses ............................................................. 41 Table A-10: SCRAM Thermal + Pressure Stresses ................................................................................ 42 Table A-11: SCRAM Blowdown Thermal + Pressure Stresses .............................................................. 43 Table A-12: Blowdown Thermal + Pressure Stresses ............................................................................ 43 Table A-13: List of Computer Files for Revision 000 .............................................................................. 44 Page 7

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

List of Figures Page Figure 2-1: SIF Solution Model .............................................................................................................. 10 Figure A-1: Material Assignment............................................................................................................. 31 Figure A-2: Heat Up and Cool Down ..................................................................................................... 33 Figure A-3: SCRAM ............................................................................................................................... 34 Figure A-4: SCRAM + Blowdown ........................................................................................................... 35 Figure A-5: Blowdown ............................................................................................................................ 36 Figure A-6: Locations for Thermal Gradients ......................................................................................... 37 Figure A-7: FE Model, Crevice Boundary Conditions ............................................................................ 38 Figure A-8: Structural Run Boundary Conditions .................................................................................... 39 Figure A-9: Results, Reported Locations ................................................................................................ 40 Figure B-1: Test Case for Tension (Based on Figure 10 of [4]) ............................................................. 46 Figure B-2: Test Case for Bending (Based on Figure 11 of [4])............................................................. 47 Page 8

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 1.0 PURPOSE During the Spring 2017 outage, leakage was discovered at Reactor Pressure Vessel (RPV) Instrument Nozzle 16D, which is a radial nozzle extending horizontally from the cylindrical vessel shell. Per Reference [1], the leakage is identified to be at approximately the 1 oclock position. The cause of the leakage has not been determined. However, based on industry experience, the most likely cause is intergranular stress corrosion cracking (IGSCC) either through the Alloy 182 J-Groove weld or through the Alloy 600 nozzle. A half nozzle repair was designed in which the existing nozzle will be severed and a replacement nozzle will be attached to the OD of the reactor pressure vessel (References [2] and [3]). The present concern is that a flaw in the remnant J-Groove weld could impact the structural integrity of the vessel. Flaws in the nozzle material will not propagate into the vessel material. However, a flaw in the weld metal may propagate into the low alloy steel. Since the hoop stress in the vessel at the J-groove weld is greater than the axial stress at the same location, the preferential direction for cracking is radial relative to the nozzle and axial relative to the vessel. Therefore, a radial-axial flaw is postulated to extend through the entire J-Groove weld and buttering. The purpose of this analysis is to evaluate the postulated radial-axial flaw for one fuel cycle of operation.

2.0 ANALYTICAL METHODOLOGY A radial-axial flaw at the inside corner of the nozzle penetration is evaluated based on linear elastic fracture mechanics (LEFM) and elastic plastic fracture mechanics (EPFM), as outlined below.

1. Postulate a radial-axial flaw in the J-groove weld, extending from the ID through the J-groove weld and buttering.

2. Calculate applied stress intensity factors for selected limiting transients using the stress intensity factor (SIF) solution from reference [4].

3. Compare applied stress intensity factors to ASME Section XI code criteria of IWB-3612 and IWB-3613 (Reference [6]) as applicable.

4. Calculate applied J-integral with appropriate safety factors as defined in Section 3.1 of ASME Code Case N-749 (Reference [7]).

5. Compare applied J-integral to the material J-integral at a ductile crack extension of 0.1, which will be based on the lower bound J-R curve in Reg. Guide 1.161 (Reference [13]).

6. Evaluate primary stress based on NB-3200 rules as required by IWB-3610(d)(2) (Reference [6]) and Section 3.1(c) of N-749 (Reference [7]).

Additional detail on the methodology is provided in the following subsections.

Page 9

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 2.1 Stress Intensity Factor Solution Stress intensity factor solution for quarter-elliptical corner crack at a hole from Reference [4], shown in Figure 2-1, will be used in the current flaw evaluation analysis to develop the applied stress intensity factor at the crack tip.

Figure 2-1: SIF Solution Model The formulas for the solution as developed in Reference [4] are documented below:

4

+

=( + ) 2 4

+

Where St is the membrane stress, Sb is the bending stress, a is the flaw size in the depth direction, c is the flaw size in the lateral direction, t is the plate thickness, and r is the hole radius. The final factor in the equation converts the solution for two symmetric flaws into an equation for one flaw. The remaining terms are defined below as reported in Reference [4]. The flaw evaluation in this document will be based on the depth location, which produce higher applied stress intensity values. The solution in Reference [4] was curve fitted for the range of parameters 0.2 < a/c < 2, 0.5 < r/t < 2 , (r+c)/b <0.5. It should be noted that the r/t ratio for the geometry analyzed in the current flaw evaluation is < 0.5. However, the Reference [4] SIF solution still provides reasonable and conservative estimation of the crack driving force. The parameter b is the plate half width. It is used for finite width correction (fw equation below), which is a factor that accounts for cases where the edge of the flaw at distance "r+c" from the hole centerline in Figure 2-1 reaches near the edge of the plate at distance "b" from the hole centerline. The factor approaches 1.0 as the plate width "b" becomes large. Since the RPV is very large and the crack is not near an edge of the RPV this factor is essentially 1.0. Hence, the solution is not sensitive to the parameter b. The solution is implemented in an Excel spreadsheet. Tests of the spreadsheet to verify the implementation of the equations are shown in Appendix B. The equations from Reference [4] are presented below:

Page 10

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 2 4 Fch = M + M x a + M x a x g x g x g x g x f x f 1 2 t 3 t 1 2 3 4 w a a F = M +M x +M x g xg xg xg xf xf t t

( )

Hch = H + H H x ( sin ( ) )

1 2 1 p

2 3 a a + G x a H =1+ G 1 11 x +G 12 x t 13 t t

2 3 a a + G x a H =1+ G 2 21 x +G 22 x t 23 t t

0.5 x r x ( 2 x r + n x c) a fw = sec x sec x 2x b 4 x ( b c) + 2 x n x c t 0.25 a 2 f = x ( cos ( ) ) + ( sin ( ) )

2 2 c

The factor g2 is different for tension and bending loads. For tension, g2 is determined as below with =0.85 2 3 4 1.0 + 0.358 x + 1.425 x 1.578 x + 2.156 x g =

2 2 1.0 + 0.13 x

= 1.0 ÷ 1.0 + x cos ( x )

c r

For bending, g2b is determined as below 1 + 0.358 x + 1.425 x 1.578 x + 2.156 x g =

1 + 0.13 x 1

= c 1 + x cos( x )

r a .

= 0.85 0.25 x t

For a/c <= 1 a

M = 1.13 0.09 x 1 c Page 11

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 0.89 M = 0.54 +

2 0.2 + a c

24 a

+ 14 x 1.0 1.0 M = 0.50 3

0.65 +

a c c

2 g = 1.0 + 0.1 + 0.35 x a x ( 1.0 sin ( ) ) 2 1 t 0.25 g = 1.0 + 0.04 x a

x 1 + 0.1 x ( 1.0 cos ( ) ) x 0.85 + 0.15 x 2 a 3

c t g = 1.0 0.7 x 1.0 a

x 0.2 x 1.0 a a 4

t c c a a a a p = 0.1 + 1.3 x + 1.1 x 0.7 x x t c c t 2

a a G

11

= 0.43 0.74 x 0.84 x c c

2 a a G

12

= 1.25 1.19 x + 4.39 x c c

2 a a G

13

= 1.94 + 4.22 x 5.51 x c c

2 a a G

21

= 1.50 0.04 x 1.73 x c c

2 a a G

22

= 1.71 3.17 x + 6.84 x c c

2 a a G

23

= 1.28 + 2.71 x 5.22 x c c

1.65 a

Q = 1 + 1.464 x c For a/c > 1 c

x 1 + 0.04 x c

M =

1 a a 4

c M = 0.2 x 2 a Page 12

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 4 c

M = 0.11 x 3 a 2

g = 1.0 + 0.1 + 0.35 x c a x ( 1.0 sin ( ) ) 2 1

x t a

0.25 g = 1.13 0.09 x c

x 1 + 0.1 x ( 1.0 cos ( ) ) x 0.85 + 0.15 x 2 a 3

a t c

G = 2.07 + 0.06 x 11 a c

G = 4.35 + 0.16 x 12 a c

G = 2.93 0.3 x 13 a c

G = 3.64 + 0.37 x 21 a c

G = 5.87 0.49 x 22 a c

G = 4.32 + 0.53 x 23 a 1.65 c

Q = 1 + 1.464 x a c a p = 0.2 + + 0.6 x a t After determining the SIF value from the equations listed above, a plasticity correction is applied based on the Irwin plastic zone correction. The Irwin plastic zone correction is discussed in Reference [5]. The effective crack depth is defined as the sum of the actual crack size and the plastic zone correction:

aeff = a + ry where ry for plane strain conditions is given by:

2 1 KI ry =

6 YS Where ys is the yield strength of the material. The plastic zone correction is also applied to the flaw length, c, using the applied KI at the surface point (=0°) in place of KI at the deepest point (=90°). An effective stress intensity factor (KIeff) is calculated by first calculating KI based on flaw size a and c. Then the size of the plastic zone at a and c (ry at =90° and =0°) is calculated based on KI at =90° and =0°, respectively. Then the KIeff is determined by recalculating KI utilizing the flaw dimension a + ry (=90°) and c + ry (=0°) in place of a and c, respectively.

Page 13

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 2.2 Linear Elastic Fracture Mechanics Linear Elastic Fracture Mechanics (LEFM) acceptance criteria are based on the criteria of IWB-3600 of Reference [6]. IWB-3612 states the following:

(a) Normal and Upset Conditions: KI < KIC/10 (b) Emergency and Faulted Conditions: KI < KIC/2 In the above, KIC is the fracture toughness based on crack initiation defined in A-4200(b) of Reference [6].

At regions of discontinuity such as the J-groove weld, IWB-3613(a) states that for conditions when the pressure is less than 20% of the Design Pressure (design pressure is [ ] Reference [1]) and the temperature is greater than RTNDT, the acceptance criterion for normal and upset condition is KI < KIC/2 which is used in this calculation for low pressure conditions.

2.3 Elastic Plastic Fracture Mechanics The Elastic Plastic Fracture Mechanics (EPFM) analysis uses ASME Code Case N-749 (Reference [7]). The methodology is described in the following subsections.

2.3.1 Screening Criteria ASME Code Case N-749 states that EPFM acceptance criteria are applicable to ferritic steel components on the upper shelf of the Charpy energy curve when the metal temperature exceeds the upper shelf transition temperature, Tc. The NRC has proposed a modification to the Code Case definition of Tc1 (Reference [8]), which is considered for this analysis and defined below

= 154.8 + 0.82 x 2.3.2 Acceptance Criteria For this analysis the acceptance criteria of Section 3.1 of N-749 (Reference [7]) based on limited ductile crack extension are utilized. Section 3.1 of Reference [7] states that the flaw is acceptable if the crack driving force, as measured by the applied J-integral (Japp) with appropriate structural factors applied to the loads, is less than the J-integral of the material at a ductile crack extension of 0.1 inch (J0.1). The structural factors specified are given in Table 2-1.

Table 2-1: EPFM Structural Factors Primary Secondary Operating Condition Evaluation Method (SFp) (SFs)

Normal/Upset J0.1 limited flaw extension 2.0 1.0 Emergency/Faulted J0.1 limited flaw extension 1.5 1.0 1

A slightly different equation (Tc = 170.4°F+0.814xRTNDT) is provided in RG 1.147, draft rev. 18 (Reference [16])

which gives a higher Tc by approximately 15°F, but does not impact the results of this analysis.

Page 14

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

For this analysis the crack driving force, J, is estimated based on small scale yielding as described below. The stress intensity factors due to primary stresses (KIP) and the stress intensity factors due to secondary stresses (KIS) are calculated using the method described in Section 2.1, including the plastic zone correction, which is applied prior to application of structural factors per Section 4.1 of Reference [7]. Per Section 3.1(c) of Reference [7],

residual stresses do not need to be included in the EPFM analysis.

With KIP and KIS calculated as described above, the applied J-integral is calculated as

+

=

where E=E/(1-2). The applied J-integral calculated as described above is acceptable if it is less than J0.1.

2.4 Primary Stress Evaluation IWB-3610(d)(2) of Reference [6] and 3.1(c) of Reference [7] require that the primary stress limits of NB-3200 of Reference [9] be satisfied considering a local area reduction of the pressure retaining membrane equal to the area of the flaw. For this evaluation, this check will be performed by confirming that the area of the flaw and any existing material removed by the modification are balanced by metal added by the weld pad, new J-groove weld, and fillet. Appropriate adjustments for difference in strengths of materials are made per the rules of NB-3336 (Reference [9]).

Page 15

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 3.0 ASSUMPTIONS 3.1 Unverified Assumptions There are no unverified assumptions used in this calculation.

3.2 Justified Assumptions The following justified assumptions are used in this analysis:

1. Based on review of the stress-strain curves for [ ] in [10], there is assumed to be a uniform weld residual stress of [ ] (slightly above room temperature yield) over the depth of the J-groove weld and butter, which is balanced by a uniform compressive stress over the remaining thickness. This assumed stress distribution is then converted to an equivalent bending stress for use in the SIF solution described in Section 2.1. The equivalent bending stress Sb (estimated based on a local stress distribution) is applied as a remote stress, and would then be amplified by stress concentration effects accounted for in the SIF solution.

3.3 Modeling Simplifications The following modeling simplifications are used in this analysis:

1. The SIF solution used (Section 2.1) is based on a corner flaw in a flat plate with a hole under remote uniaxial tension and bending stresses. This is a conservative simplification since the stress concentration at a hole is higher with uniaxial tension than with biaxial tension. The ratio of the hole radius to plate thickness, r/t is <0.5, however the SIF solution of Reference [4] still provides reasonable and conservative estimation of the crack driving force.

Page 16

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 4.0 DESIGN INPUTS 4.1 Geometry The original geometry is described in Reference [1], with the half nozzle repair design shown in Reference [2].

The reactor pressure vessel and the instrumentation nozzle 16D are described by the following key dimensions:

Table 4-1: Key Dimensions Dimension Value Reference Radius to Base Metal [ ] [2]

Reactor Vessel Wall Thickness (min) [ ] [1] [ ]

Existing Weld Reinforcement Thickness (min) [ ] [1] [ ]

Cladding thickness [ ] [1] [ ]

Depth of J-groove Butter (nominal from cladding) [ ] [1] [ ]

Width of J-Groove Butter [ ] [1] [ ]

Diameter of Bore at J-Groove Weld [ ] [1] [ ]

The postulated flaw size is taken as the depth and width of the J-groove and butter plus [ ] to allow for crack growth by SCC (see Section 3.2, item 2) and fatigue over one fuel cycle. This results in a depth, a =

[ ] and length, c = [ ] The thickness considered for the SIF solution is [

] (sum of min wall and min existing weld pad); the repair pad thickness is not credited for calculating the SIFs.

4.2 Materials The materials used in the design are summarized below:

RV Shell SA-533 Gr. B, Class 1 [3]

Existing J-Groove Weld and Butter [ ] [3]

Existing Nozzle [ ] [3]

Cladding [ ] [3]

Existing Weld Reinforcement [ ] [3]

Replacement Nozzle SB-167, UNS N06690 (Alloy 690) [3]

Repair Weld and Nozzle to Weld Pad Weld ERNiCrFe-7A, UNS N066054, (Alloy 52M) [3]

Page 17

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 4.2.1 Mechanical Properties From Reference [12], the elastic modulus of the SA-533 base material at a representative temperature of 550°F is approximately 26700 ksi, and Poissons ratio is taken as 0.3. For the EPFM analysis, this results in E=26700/(1-0.32) 29300 ksi. For the plastic zone correction, a yield strength of 42.7 ksi at 550°F is used based on Reference [12] values.

Per Reference [12], Sm for Alloy 600 and Alloy 690 is 23.3 ksi, and the Sm for the SA-533 base metal is 26.7 ksi.

4.2.2 Fracture Material Properties The 57 EFPY adjusted RTNDT (ART) of the RV shell plate at the location of nozzle 16D (280° azimuth) is

[ ] per Reference [1] ( [ ] ) and is conservatively considered for this analysis although the current EFPY is much lower. This value of RTNDT will be utilized with the KIC fracture toughness for crack initiation curve defined in Article A-4200 of Section XI (Reference [6]) as

= 33.2 + 20.734exp[0.02( )]

The crack initiation KIC upper shelf toughness of 200 ksiin is achieved at T-RTNDT > 105 °F.

The J-integral resistance (J-R) curve, needed for the EPFM method of analysis, is obtained from the following correlation for reactor pressure vessel plate in Regulatory Guide 1.161, Section 3.3.1 (Reference [13])

= ( ) exp( ( ) )

where MF is a margin factor, and a is the crack extension. Ci are constants which depend on the crack tip temperature and the Charpy V-notch upper-shelf energy as defined below

= exp(2.44 + 1.13 ln( ) 0.00277 )

= 0.077 + 0.116 ln

= 0.0812 0.0092 ln

= 0.409 where CVN is the Charpy V-notch upper-shelf energy in ft-lbs, and T is the crack tip temperature in °F. The margin factor, MF, of 0.749 is utilized for the analysis. Section 3.3.1 of Reference [13] states that the use of this model should be justified if the sulfur content of the plate is greater than 0.018 wt%. Per Reference [1] (

[ ] ) the nozzle 16D is located in Shell Ring #2 which is comprised of plates 17-1, 17-2, and 17-3. These plates each have [ ] wt% sulfur per Reference [1] ( [ ] ). Therefore, use of this model is applicable.

An additional input for the J-R model is the charpy upper shelf energy (USE), which is provided in Reference [1]

([ ] ) at this location as follows:

Initial Longitudinal USE = [ ]

Initial Transverse USE = [ ]

57 EFPY Transverse USE = [ ]

Per the discussion in the Reg. Guide 1.161, CVN value used in the J-R model should be for the proper orientation, which is longitudinal for axial flaws and transverse for circumferential flaws. Since hoop stresses are higher than axial stresses, an axial flaw is the preferred orientation for cracking, and this analysis applies the higher hoop Page 18

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) stresses. Based on the same [ ] decrease applied to the transverse USE, the 57 EFPY longitudinal USE would be approximately [ ] In this report, the results will be shown with J0.1 using both the bounding transverse USE of [ ] and the more pertinent longitudinal USE of [ ]

4.3 Applied Stresses 4.3.1 Operating Stresses An axisymmetric finite element model was developed to generate transient stress results and is documented in Appendix A. The transients defined in [ ] of Reference [1] were reviewed and bounding transients were selected based on pressure and temperature ranges. Transient stress analyses were performed for the following bounding design transients, which are described in more detail in Appendix A:

• Heatup and Cooldown (Normal Condition) - [

] of Reference [1])

• SCRAM (Normal/Upset) - [

] of Reference [1])

• SCRAM + Blowdown (Emergency Condition) - [

] of Reference [1])

• Blowdown (Faulted Condition) - [ ]

of Reference [1])

The linearized through wall bending hoop stresses are taken from the finite element output for the path line LongPath through the RV shell and existing reinforcement pad, and contribute to the remote applied bending stress, Sb, used for the SIF solution. These bending stresses result from thermal stresses and discontinuity effects, and are therefore categorized as secondary for use in the EPFM portion of the analysis. Since the finite element model uses an equivalent sphere with a radius of 2.5 times the actual radius, the membrane stresses are overly conservative, and thus the remote tensile stress, St, applied for the SIF solution is calculated using the basic hoop stress formula, pRi/t, where p is the pressure, Ri is the inside radius ( [ ] ), and t is the thickness

([ ] ).

4.3.2 Weld Residual Stress As noted in Section 3.2, item 1 it is assumed that the weld residual stress over the depth (d) of the J-Groove weld and butter ( [ ] , Table 4-1) is at a uniform tensile stress of t = [ ] , which is balanced by a uniform stress over the remainder of the total thickness (t - d = [ ] ) such that the compressive stress is This stress distribution has a net tensile stress, St, of 0 ksi. The equivalent remote bending stress, Sb, is defined by Page 19

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 4.3.3 Crack Face Pressure Crack face pressure loading is accounted for in a similar manner to the welding residual stress. A uniform tensile stress equal to the applied pressure is considered over the crack depth, a. The stress over the remaining thickness is equal to zero. The equivalent remote tensile load is given by for the postulated flaw depth. The equivalent bending stress for the postulated flaw depth is 5.0 COMPUTER USAGE 5.1 Computer Software The calculations in the main body of this report are performed using Microsoft Excel spreadsheets.

Documentation of the ANSYS (Reference [14]) runs reported in Appendix A are provided in that appendix.

5.2 Computer Files The excel spreadsheet utilized for the fracture mechanics analysis is listed in Table 5-1 stored in coldstor at the location listed below.

\cold\General-Access\32\32-9000000\32-9271581-000\official Table 5-1: Computer Files CRC Checksum Size (Bytes) Date and Time File Name 49696 547271 May 15 2017 11:32:10 Limerick_N16D_w_Pad_LEFM_EPFM_R3.xlsm Page 20

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 6.0 CALCULATIONS 6.1 LEFM Evaluation Applied stress intensity factors are calculated using the SIF solution from Section 2.1 and the various sources of stresses described in 4.3. The SIFs including plastic zone correction were calculated using the spreadsheet Limerick_N16D_w_Pad_LEFM_EPFM_R3.xlsm (see Table 5-1) at both the =0° and =90° locations and compared to the acceptance criteria described in Section 2.2. The KIC value shown in the table was calculated using a temperature equal to the minimum of the metal temperature and fluid temperature. For normal and upset conditions below a pressure of [ ] , the criteria of IWB-3613(a) is considered such that the required margin is reduced to 2 from 10.

The results documented in Table 6-1 show that the Emergency and Faulted condition transients satisfy the required LEFM margins in all cases. For the Normal and Upset conditions the low temperature/pressure cases satisfy the required LEFM margin. All cases which do not satisfy LEFM are above the temperature 2,

[ ]

and therefore EPFM method of analysis is applicable, and the results of that analysis are documented in the next subsection.

2 The equation provided in RG 1.147, draft rev. 18 (Reference [16]) is Tc = 170.4°F+0.814xRTNDT = 170.4+0.814*

[ ] This difference has no impact on results since all the same time points would still be at upper shelf temperature.

Page 21

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Table 6-1: LEFM Results Membrane Stresses Bending Stresses Total Applied Stress Time Pressure Fluid Temperature Metal Temperature Pressure (pRi/t) Crack Face Pressure FE Model Bending WRS Crack Face Pressure St Sb Transient Service Level hr psig °F °F ksi ksi ksi ksi ksi ksi ksi HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset HUCD Normal/Upset BD Emergency/Faulted BD Emergency/Faulted BD Emergency/Faulted BD Emergency/Faulted BD Emergency/Faulted BD Emergency/Faulted SCRAM Normal/Upset SCRAM Normal/Upset SCRAM Normal/Upset SCRAM Normal/Upset SCRAM Normal/Upset SCRAM Normal/Upset SCRAM Normal/Upset SCRAM Normal/Upset SCRAM Normal/Upset SCRAM Normal/Upset SCRAM Normal/Upset SCRAM_BD Emergency/Faulted SCRAM_BD Emergency/Faulted SCRAM_BD Emergency/Faulted SCRAM_BD Emergency/Faulted SCRAM_BD Emergency/Faulted SCRAM_BD Emergency/Faulted Page 22

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Table 6 1: LEFM Results (continued)

K at = Plastic Zone Plastic Zone Corrected K at =

0° 90° = 0° = 90° 0° 90° Time KI KI ry ry KIeff KIeff KIC Transient Service Level KIC/K at = 0 KIC/K at = 90 Req'd Margin LEFM Check? EPFM Applicable?

hr ksiin ksiin in in ksiin ksiin ksiin HUCD Normal/Upset OK Below EPFM Temperature Range HUCD Normal/Upset OK EPFM Temperature Range HUCD Normal/Upset No Good EPFM Temperature Range HUCD Normal/Upset No Good EPFM Temperature Range HUCD Normal/Upset No Good EPFM Temperature Range HUCD Normal/Upset No Good EPFM Temperature Range HUCD Normal/Upset No Good EPFM Temperature Range HUCD Normal/Upset No Good EPFM Temperature Range HUCD Normal/Upset No Good EPFM Temperature Range HUCD Normal/Upset No Good EPFM Temperature Range HUCD Normal/Upset No Good EPFM Temperature Range HUCD Normal/Upset No Good EPFM Temperature Range HUCD Normal/Upset OK EPFM Temperature Range HUCD Normal/Upset OK EPFM Temperature Range HUCD Normal/Upset OK EPFM Temperature Range HUCD Normal/Upset OK Below EPFM Temperature Range BD Emergency/Faulted OK EPFM Temperature Range BD Emergency/Faulted OK EPFM Temperature Range BD Emergency/Faulted OK EPFM Temperature Range BD Emergency/Faulted OK EPFM Temperature Range BD Emergency/Faulted OK EPFM Temperature Range BD Emergency/Faulted OK EPFM Temperature Range SCRAM Normal/Upset No Good EPFM Temperature Range SCRAM Normal/Upset No Good EPFM Temperature Range SCRAM Normal/Upset OK EPFM Temperature Range SCRAM Normal/Upset No Good EPFM Temperature Range SCRAM Normal/Upset No Good EPFM Temperature Range SCRAM Normal/Upset No Good EPFM Temperature Range SCRAM Normal/Upset No Good EPFM Temperature Range SCRAM Normal/Upset No Good EPFM Temperature Range SCRAM Normal/Upset No Good EPFM Temperature Range SCRAM Normal/Upset No Good EPFM Temperature Range SCRAM Normal/Upset No Good EPFM Temperature Range SCRAM_BD Emergency/Faulted OK EPFM Temperature Range SCRAM_BD Emergency/Faulted OK EPFM Temperature Range SCRAM_BD Emergency/Faulted OK EPFM Temperature Range SCRAM_BD Emergency/Faulted OK EPFM Temperature Range SCRAM_BD Emergency/Faulted OK Below EPFM Temperature Range SCRAM_BD Emergency/Faulted OK Below EPFM Temperature Range Page 23

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 6.2 EPFM Evaluation The EPFM analysis was performed in the spreadsheet Limerick_N16D_w_Pad_LEFM_EPFM_R3.xlsm (see Table 5-1) using the methodology described in Section 2.3. The same stresses used in Section 6.1 are used for the EPFM analysis, except residual stresses are excluded per Section 3.1(c) of code case N-749. As noted in Section 4.3.1, the finite element model bending stresses are considered as secondary for the EPFM analysis. Although the Emergency and Faulted conditions satisfy the LEFM criteria, the EPFM evaluation is also performed for cases in the temperature range where EPFM is applicable; these evaluations of Emergency and Faulted conditions conservatively utilized the Normal and Upset condition safety factors. Results are shown with J0.1 values using both the bounding transverse USE of [ ] and the more pertinent longitudinal USE of [ ]

For all cases, the results are shown to be acceptable based on the bounding transverse USE.

Page 24

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Table 6-2: EPFM Results Plastic Zone Plastic Zone Correction Applied

= 0° = 0° = 90° = 90° = 0° = 90° = 0° = 0° = 90° = 90° = 0° = 90° Transverse USE Longitudinal USE Time St Sb-SbWRS KIp KIs KIp KIs ry ry KIp KIs KIp KIs Japp Japp J0.1 J0.1 Transient Service Level Japp/J0.1 Japp/J0.1 hr ksi ksi ksiin ksiin ksiin ksiin in in ksiin ksiin ksiin ksiin kips/in kips/in kips/in kips/in HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK HUCD Normal/Upset < 1, OK BD Emergency/Faulted < 1, OK BD Emergency/Faulted < 1, OK BD Emergency/Faulted < 1, OK BD Emergency/Faulted < 1, OK BD Emergency/Faulted < 1, OK BD Emergency/Faulted < 1, OK SCRAM Normal/Upset < 1, OK SCRAM Normal/Upset < 1, OK SCRAM Normal/Upset < 1, OK SCRAM Normal/Upset < 1, OK SCRAM Normal/Upset < 1, OK SCRAM Normal/Upset < 1, OK SCRAM Normal/Upset < 1, OK SCRAM Normal/Upset < 1, OK SCRAM Normal/Upset < 1, OK SCRAM Normal/Upset < 1, OK SCRAM Normal/Upset < 1, OK SCRAM_BD Emergency/Faulted < 1, OK SCRAM_BD Emergency/Faulted < 1, OK SCRAM_BD Emergency/Faulted < 1, OK SCRAM_BD Emergency/Faulted < 1, OK SCRAM_BD Emergency/Faulted < 1, OK SCRAM_BD Emergency/Faulted < 1, OK

• Temperatures at these time points are below Tc, results are for information only.

Page 25

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary) 6.3 Primary Stress Evaluation Primary stresses are evaluated as described in Section 2.4, by showing that the repair configuration adds sufficient amount of cross-sectional area to account for the reduction in cross-sectional area equal to the area of the postulated flaw. All areas calculated in the following lines are for one side of the symmetric configuration.

The area of the postulated J-groove flaw including the crack growth is calculated as the area of the trapezoid, with height equal to the flaw depth, a, base equal to the flaw length, c, and the weld prep angle of [ ] (Reference

[1], [ ] ).

J-Groove Depth with crack growth, a= in J-Groove Width with crack growth, c= in Angle ° Area, A1 = (c-a*tan( [ ] °))*a+1/2*a*a*tan( [ ] °) in2 The repair configuration adds material by the new Alloy 52M weld pad, J-groove weld, and fillet; area is removed from the existing weld reinforcement buildup due to bore for the replacement nozzle. The repair also exposes low alloy steel to the reactor coolant, and per Reference [15] a corrosion rate of [ ] is applicable. For the calculation, area removed from the low alloy steel will be increased by the ratio of Sm for SA-533 to Alloy 690 and Alloy 600 (26.7ksi/23.3ksi) in order to account for the difference in strength per NB-3336 (Reference [9]).

Based on Reference [2], the area of Alloy 52M weld added by the repair pad, J-groove weld, and fillet is calculated as Pad Diameter (Min), D1 in Nozzle Bore Diameter (Max), D2 in Pad Thickness (Min), t1 in J-Groove Fillet Size, t2 in Pad + Fillet Area, A2 = (D1-D2)/2*t1+0.5*t2^2 in2 The low alloy steel area lost due the replacement nozzle bore and 20 years (conservatively used in lieu of the 2 years considered in the calculation) of corrosion is Max Bore Diameter, D2 in Original Bore Diameter, D3 in Max Boring Depth, L1 in Bore Area Removed, A3 = (D2-D3)/2*L1 in2 Conservative exposed LAS length, L2 in Radial corrosion loss, R1= [ ]

• 20 years in Corrosion Area Removed, A3= L2*R1 in2 Total LAS area removed (A3+A4) in2 Sm(SA533)/Sm(Alloy 690) 1.146 Effective LAS area removed, A5 = 1.146*(A3+A4) [ ] in2

[

]

Since the net area added by the repair exceeds the area of the postulated flaw, the primary stress criteria of IWB-3610(d)(2) of Reference [6] and 3.1(c) of Reference [7] are considered to be satisfied for one fuel cycle.

Page 26

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

7.0 CONCLUSION

S Based on a combination of Linear Elastic Fracture Mechanics (IWB-3610 of ASME Section XI, Reference [6])

and Elastic Plastic Fracture Mechanics (ASME Code Case N-749, Reference [7]) evaluations, the postulated flaw in the as-left J-groove weld of nozzle 16D at Limerick Unit 2 is shown to be acceptable for one fuel cycle following the Spring 2017 outage.

For temperatures below the upper shelf temperature the LEFM analysis based on IWB-3610 (Reference [6])

criteria is applicable and the limiting cases are summarized below from Table 6-1:

Transient HUCD SCRAM + BD Service Level Normal/Upset Emergency/Faulted Pressure (psig)

Temperature (°F)

KIeff (ksiin)

KIC (ksiin)

Margin, KIC/KIeff Required Margin Result OK OK For temperatures above the upper shelf temperature the EPFM analysis based on Code Case N-749 (Reference

[7]) criteria is applicable and the limiting cases are summarized below from Table 6-2:

Transient SCRAM SCRAM + BD Service Level Normal/Upset Emergency/Faulted Pressure (psig)

Temperature (°F)

Japp (kips/in)

Transverse USE J0.1 (kips/in)

Longitudinal USE J0.1 (kips/in)

Japp/J0.1 (Transverse USE)

Japp/J0.1 (Longitudinal USE)

Result OK OK The primary stress criteria of IWB-3610(d)(2) of Reference [6] and 3.1(c) of Reference [7] are satisfied for one fuel cycle since the net area added by the repair exceeds the area of the postulated flaw as demonstrated in 6.3.

Page 27

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

8.0 REFERENCES

References identified with an (*) are maintained within Exelon Records System and are not retrievable from AREVA Records Management. These are acceptable references per AREVA Administrative Procedure 0402-01, . See page 3 for Project Manager Approval of customer references.

1. [

]

2. [

]

3. [

]

4. Newman, JC and Raju, IS, Stress-Intensity Factor Equations for Cracks in Three-Dimensional Finite Bodies Subjected to Tension and Bending Loads, NASA Technical Memorandum 85793.

5. T.L. Anderson, Fracture Mechanics: Fundamentals and Applications, CRC Press, 1991.

6. ASME Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, Division 1, 2007 Edition including Addenda through 2008.

7. Cases of the ASME Boiler and Pressure Vessel Code, Case N-749, Alternative Acceptance Criteria for Flaws in Ferritic Steel Components Operating in the Upper Shelf Temperature Range,Section XI, Division I.

8. Federal Register, Volume 81, Page 10787 (81 FR 10787), Wednesday March 2, 2016, Proposed Rules.

9. ASME Boiler and Pressure Vessel Code,Section III, Rules for Construction of Nuclear Facility Components, Division 1, 2007 Edition, including Addenda through 2008.

10. [

]

11. *[

]

12. ASME Boiler and Pressure Vessel Code,Section II, Part D, Materials - Properties, 2007 Edition including Addenda through 2008.

13. Regulatory Guide 1.161, Evaluation of Reactor Pressure Vessels with Charpy Upper-Shelf Energy Less than 50 ft-lb, June 1995.

14. ANSYS 16.0 Finite Element Code, ANSYS Inc., Canonsburg, PA.

15. AREVA Document 51-9271544-001, Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification.

16. DRAFT Regulatory Guide DG-1296, Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1, Proposed Revision 18 of Regulatory Guide 1.147, dated March 2016 (ADAMS No.

ML15027A202).

Page 28

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

APPENDIX A: OPERATING STRESS ANALYSIS A.1 Purpose This appendix (Appendix A) is to describe development of the finite element (FE) model, the loads applied to FE model, and extracting stresses to support the fracture mechanics analysis presented in the main body of this document. Note that this appendix contains both AREVA and GE proprietary information.

A.2 Methodology The methodology consists of:

1. Building an axially symmetric FE model which includes a section of the RV base material, a section of the original nozzle, the original J-groove weld, cladding, the new replacement nozzle, weld build-up and weld between replacement nozzle and weld build-up. The radius of the RV in the FE axi-symmetrical model was magnified for conservatism by 2.5 to account for difference in the membrane stresses between a sphere and cylinder of the same thickness and radius. There are two models with identical mesh: one for the thermal analysis and one for the structural analysis.

2. Applying the temperature and heat transfer coefficient of applicable transients for normal, upset, emergency and faulted conditions (Heat Up and Cool Down, SCRAM, Blowdown during SCRAM, and Blowdown transients) on the thermal FE model.

3. Defining the locations of interest for thermal gradients within the structure, obtaining values of thermal gradients for entire transient from runs on thermal model, and selecting the time points for structural runs.

4. Applying pressure and temperature on the structural model for the time points identified in the previous step to obtain stresses resulting from pressure and thermal gradients.

5. Defining two (2) stress classification lines across the thickness of the RV, one is near the nozzle opening; the second is away from discontinuity. Listing stress components at these stress classification path lines to support fracture mechanics analysis.

A.3 Assumptions and Modeling Simplifications

1. There are no unverified assumptions used within this appendix. Justified assumptions and modeling simplifications are detailed as follows.

2. Axially symmetric model is used to calculate result stresses. In order to account for difference in membrane and bending stresses of the cylindrical shell and spherical shell of the same radius and the wall thickness, the radius of the shell was magnified for conservatism by factor of 2.5. This value is based on experience with modeling 2-D spherical shell for a cylinder-in-a-cylinder configuration.

3. Weld overlay on inner surface of the shell specific for Limerick Unit 2 (as shown on [ ] of reference [1]) was neglected. The effect of the buildup on stresses at the location of interest is negligible because the thickness of the weld overlay buildup is negligible compared to the thickness of the vessel, and the properties of the Alloy 82 overlay are equivalent to the Alloy 182 J-groove weld.

4. The material properties of the weld buildup material on the RV shell is assumed to be consistent with that of the RV shell per direction provided in Section 6.0 of reference [3].

5. Geometry of the replacement nozzle is approximate. The inner radius of new nozzle is equal to inner radius of the original nozzle. Such approximation is acceptable since the area of interest is in the shell, far from the nozzle-to-build up weld.

Page 29

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

6. The time of faulted blow down transient pressure and temperature drop was reduced due to legibility concerns of the input document from [ ] seconds to [ ] seconds. Such change makes the event more severe and is therefore acceptable.

7. Heat transfer coefficient inside nozzle is set to [ ] BTU/hr-ft2-ºF and to [ ] BTU/hr-ft2-ºF on insulated surfaces of the nozzle and RV shell. These values are based on experience with modeling similar geometries. Although other values can be justified, the difference is deemed insignificant for the purpose of this analysis, which is to provide stresses in the RV shell relatively far from the nozzle opening.

A.4 Design Inputs The geometry of the model is based on information obtained from reference [2], page 75 of stress report [

] and drawing [ ] of reference [1]. The thickness of the replacement nozzle and weld to new buildup geometry in FE model is approximate. The difference between modeled and actual geometry is considered insignificant for the stresses in the section of the RV used for fracture mechanics analysis.

Material designations for the FE model can be found in [ ] of reference [1] for the original configuration and in [2] for the repair configuration.

Table A-1: Material Designations Item Material Designation Reference Reactor Vessel, Base Material SA-533, Grade B, Cl.1 Reactor Vessel, Cladding

[

] [ ]

Original Nozzle [ ] of reference [1]

Original J-groove Weld

[

]

Repair Nozzle SB-167, Alloy 690 J-groove Weld to Repair Nozzle Alloy 690 [2]

Repair Weld Build Up Alloy 690 Note:

1. [ ] base material properties are assumed for RV cladding.

2. [ ] base material properties used within the analytical evaluation.

Page 30

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Figure A-1: Material Assignment A.4.1 Design Conditions Design conditions: pressure [ ] psig, temperature [ ] ºF (page 75 of stress report [

] of reference [1]). No external piping loads are considered in this appendix (consistent with page 72 of stress report [ ] of reference [1]).

A.4.2 Transient Definitions Reference [1] is used extensively within this section. Unless stated otherwise, it is always referring to drawing

[ ] of reference [1]. Such notation is used for better readability. The transients defined in

[ ] of Reference [1] were reviewed and bounding transients were selected based on pressure and temperature ranges.

The Heat Up and Cool Down transient described in Table A-2 and Figure A-2 refers to [

] on Reference [1]. This transient is part of Normal and Upset Conditions.

The SCRAM transient described in Table A-3 and Figure A-3 refers to [

] on Reference [1]. This transient is part of Normal and Upset Conditions.

Page 31

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

The SCRAM + Blowdown transient described in Table A-4 and Figure A-4 refers to [

] on Reference [1]. This transient is an Emergency Condition.

The Blowdown transient described in Table A-5 and Figure A-5 refers to [

] on Reference [1]. This transient is a Faulted Condition.

A heat transfer coefficient of [ ] BTU/hr-ft2-°F is used on the RV shell inner surface. This value is calculated using equation: = [ ] (reference [1], Section [ ] ); where the flow: Q = [ ] lbs/hr (reference [1], Exelons response table).

Values of heat transfer coefficient of [ ] BTU/hr-ft2-°F at the nozzle inner surface, and [ ] BTU/hr-ft2-°F for the insulated condition on the model outer surfaces are considered appropriate in this location (see Section A.3).

In accordance with Reference [1], the following changes due to MUR are incorporated:

1) Operating temperatures are increased from [ ]

2) Operating pressure is increased from [ ]

3) In the SCRAM events, [ ]

Table A-2: Heat Up and Cool Down Time Temperature Pressure Time Temperature Pressure

[hour] [°F] [psig] [hour] [°F] [psig]

0.01000 8.00001 1.00000 9.00000 1.80400 9.12100 2.33000 9.28500 2.78000 9.44000 3.22000 9.55900 3.53000 9.76500 3.92000 9.93000 4.28000 10.12000 4.60000 10.29000 4.98000 10.51000 5.27000 10.78000 5.53000 10.94667 6.53000 13.24667 6.53001 15.00000 6.69668 6.69669 8.00000 Page 32

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Figure A-2: Heat Up and Cool Down Table A-3: SCRAM Time Temperature Pressure

[hour] [°F] [psig]

0.01000 1.00000 1.00278 1.00417 1.00833 2.29833 3.82833 4.82833 4.82834 4.99501 4.99502 6.00000 Page 33

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Figure A-3: SCRAM Table A-4: SCRAM + Blowdown Time Temperature Pressure

[hour] [°F] [psig]

0.01000 1.00000 1.16667 1.49367 1.83967 2.23667 2.64667 2.98667 3.91667 6.00000 Page 34

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Figure A-4: SCRAM + Blowdown Table A-5: Blowdown Time Temperature Pressure

[hour] [°F] [psig]

0.01000 1.00000 1.00361 (Note 1) 2.00000 Note 1: This time step is modeled as [ ] seconds ( [ ] hours) instead of [ ] seconds (

[ ] hours). This has no impact on results.

Page 35

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Figure A-5: Blowdown Page 36

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

A.5 Calculations Finite Element Model: The axially symmetric finite element model was built in ANSYS R16. The dimensions of the replacement nozzle are approximate.

A.5.1 Thermal Analysis The temperatures listed in Table A-2 through Table A-5 were applied on all wetted surfaces. The outer surfaces of the replacement nozzle and the part of original nozzle inserted into the RV were thermally coupled with inner surface of the opening bore. Input data for transient thermal analyses are listed in Section A.4.2. The thermal runs are documented in computer output files with names *_thRun.out.

A.5.2 Structural Analysis The time-points for structural runs were selected based on the pressure transients (listed in Table A-2 through Table A-5 ) and thermal gradients (temperature differences) between locations of interest. The approximate location for thermal gradients can be found on Figure A-6. The thermal gradient listing can be found in computer files *_dT.out.

A list of time-points for which the structural runs were submitted can be found in Table A-6. The pressure was applied on all wetted surfaces, including outer surface of original nozzle and inner surface of shell hole Figure A-8 (also shown on Figure A-7). Nodes on the outer edge of the shell were fixed in hoop direction, the cap force was applied for all structural runs on the end of replacement nozzle. The body temperature corresponding to the time of the transient is applied to the structural model from result file from thermal transient analysis of Section A.5.1. The structural runs are documented in computer files *_stRun.out.

Computer output file dCase_stRun.out documents in the first load step the design case run.

Figure A-6: Locations for Thermal Gradients Page 37

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Figure A-7: FE Model, Crevice Boundary Conditions Table A-6: Time Points Selection for Stress Runs Heat up / Cooldown SCRAM SCRAM Blowdown Blowdown time time time time

[ hour ] [ hour ] [ hour ] [ hour ]

1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 6 6 6 6 7 7 8 8 9 9 10 10 11 11 12 13 14 15 16 Page 38

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Figure A-8: Structural Run Boundary Conditions The computer output file FractureData.out contains several formatted tables. Each transient and each stress classification path line is represented in separate table. Each table lists the transient time points, metal temperature at the location of original weld, along with membrane and bending hoop and axial component stresses at the stress classification line away from the opening discontinuity. Refer to the header of each table (in file FractureData.out) for the origin of stresses. The stRun in the header of the table is the designation for the thermal plus pressure origin of reported stresses. Refer to Table A-7 and Table A-8 for the description of listing as it appears in output file FractureData.out.

Table A-7: Stress Origin Description Table Header Reported Stresses from the Structural Runs

../DesignCase/dCase_Run Design Case (1st load step)

../HeatCool/HC_stRun Heat Up/Cool Down, Pressure + Temperature

../BlowDown/BD_stRun Blowdown, Pressure + Temperature

../Scram/SC_stRun SCRAM, Pressure + Temperature

../ScramBlow/SB_stRun Scram Blowdown, Pressure + Temperature Page 39

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Table A-8: Column Description

1. Item 1 table line number 2 time in the transient 3 temperature at location of original J-groove weld 4 axial membrane stress 5 axial bending stress, shell inner surface, bending I 6 axial bending stress, shell outer surface, bending O 7 hoop membrane stress 8 hoop bending stress, shell inner surface, bending I 9 hoop bending stress, shell outer surface, bending O Stress components are listed in the cylindrical coordinate system with the RV shell centerline perpendicular to the display plane, hoop direction is the circumferential direction of entire RV shell, and radial direction is radial direction of entire RV shell. Also refer to Figure A-9 for approximate location of the stress classification lines ShortPath and LongPath. Table A-9 through Table A-12 list the membrane axial and bending hoop (at RV shell ID) stress components from selected stress runs (reference: output file FractureData.out).

Figure A-9: Results, Reported Locations Page 40

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Table A-9: Heat Up / Cool Down Thermal + Pressure Stresses Path: LongPath time TWELD Axial Stress [ psi ] Hoop Stress [psi ]

[ hour ] [°F] membrane bending I bending O membrane bending I bending O 1 0.01 2 2.9 3 5.53 4 6.652 5 6.6743 6 6.6966 7 6.7781 8 6.8317 9 8 10 8.1193 11 8.1554 12 8.2635 13 10.946 14 11.028 15 11.11 16 15 Path: ShortPath time TWELD Axial Stress [ psi ] Hoop Stress [psi ]

[ hour ] [°F] membrane bending I bending O membrane bending I bending O 1 0.01 2 2.9 3 5.53 4 6.652 5 6.6743 6 6.6966 7 6.7781 8 6.8317 9 8 10 8.1193 11 8.1554 12 8.2635 13 10.946 14 11.028 15 11.11 16 15 Page 41

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Table A-10: SCRAM Thermal + Pressure Stresses Path: LongPath time TWELD Axial Stress [ psi ] Hoop Stress [psi ]

[ hour ] [ ° F ] membrane bending I bending O membrane bending I bending O 1 0.01 2 1.0031 3 2.2983 4 3.828 5 4.828 6 4.953 7 4.995 8 5.123 9 5.167 10 5.3 11 6 Path: ShortPath time TWELD Axial Stress [ psi ] Hoop Stress [psi ]

[ hour ] [ ° F ] membrane bending I bending O membrane bending I bending O 1 0.01 2 1.0031 3 2.2983 4 3.828 5 4.828 6 4.953 7 4.995 8 5.123 9 5.167 10 5.3 11 6 Page 42

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Table A-11: SCRAM Blowdown Thermal + Pressure Stresses Path: LongPath time TWELD Axial Stress [ psi ] Hoop Stress [psi ]

[ hour ] [ ° F ] membrane bending I bending O membrane bending I bending O 1 0.01 2 1 3 1.2484 4 1.33 5 3.91 6 6 Path: ShortPath time TWELD Axial Stress [ psi ] Hoop Stress [psi ]

[ hour ] [ ° F ] membrane bending I bending O membrane bending I bending O 1 0.01 2 1 3 1.2484 4 1.33 5 3.91 6 6 Table A-12: Blowdown Thermal + Pressure Stresses Path: LongPath time TWELD Axial Stress [ psi ] Hoop Stress [psi ]

[ hour ] [ ° F ] membrane bending I bending O membrane bending I bending O 1 0.01 2 1.0004 3 1.09 4 1.11 5 1.21 6 2 Path: ShortPath time TWELD Axial Stress [ psi ] Hoop Stress [psi ]

[ hour ] [ ° F ] membrane bending I bending O membrane bending I bending O 1 0.01 2 1.0004 3 1.09 4 1.11 5 1.21 6 2 Page 43

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

A.6 Computer Files The computer files pertinent to revision 000 of this document are located in ColdStor directory:

/32-9271581-000/official/AppendixA ANSYS Release 16.0 (latest EASI list version, Reference [14]) was used for all FE runs documented herein. Use of this version of ANSYS is acceptable since error notices were reviewed and none was found applicable to this analysis. The installation verification files can be found under directory:

/32-9271581-000/official/AppendixA/Verification The computer used for this analysis is a multi-node server (auslynchpcc03), the computing node used to run this analysis was selected automatically by queuing handling software to be auslynchpc33. Queue number to run this job was 124625. The runs, including verifications, were submitted in interactive mode by Martin Kolar (preparer of revision 000).

The hardware platform: Intel [ ] (node: auslynchpc33);

operating system: Red Hat Enterprise Server release [ ]

Test runs rendered acceptable results.

Table A-13: List of Computer Files for Revision 000 CRC Checksum Size (Byte) Modified Date Time File Name

... /AppendixA:

19003 2795 May 14 2017 21:24:45 RunLimerickAll.sh

... /AppendixA/BlowDown:

03994 36599 May 14 2017 21:30:52 BlowDown_dT.out 18382 1099 May 12 2017 22:01:11 BlowDown_stRun.mac 34476 44390 May 14 2017 21:31:01 BlowDown_stRun.out 26595 1047 May 14 2017 21:19:19 BlowDown_thRun.mac 59712 97075 May 14 2017 21:30:49 BlowDown_thRun.out 13151 515 May 11 2017 13:47:52 Blowdown_TrDef.mac

... /AppendixA/DesignCase:

43221 32614 May 14 2017 21:28:35 DesignCase_stRun.out 57283 1063 May 12 2017 16:17:54 dCase_stRun.mac

... /AppendixA/FractureData:

02625 2454 May 12 2017 22:30:03 FractureData.mac 03638 322890 May 14 2017 21:31:39 FractureData.out

... /AppendixA/HeatCool:

49952 3360 May 11 2017 21:10:55 HUCD_TrDef.mac 63110 47525 May 14 2017 21:29:31 HeatCool_dT.out 28649 1291 May 12 2017 23:10:59 HeatCool_stRun.mac 44877 81699 May 14 2017 21:29:48 HeatCool_stRun.out 11878 2318 May 14 2017 21:19:22 HeatCool_thRun.mac 47979 242621 May 14 2017 21:29:28 HeatCool_thRun.out Page 44

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

... /AppendixA/Scram:

61185 1287 May 11 2017 13:47:46 Scram_TrDef.mac 10648 40469 May 14 2017 21:30:18 Scram_dT.out 59681 1195 May 12 2017 22:05:24 Scram_stRun.mac 13356 61869 May 14 2017 21:30:31 Scram_stRun.out 37287 1386 May 14 2017 21:19:18 Scram_thRun.mac 00833 138539 May 14 2017 21:30:15 Scram_thRun.out

... /AppendixA/ScramBlow:

54769 38887 May 14 2017 21:31:23 ScramBlow_dT.out 07626 1103 May 12 2017 22:14:56 ScramBlow_stRun.mac 15092 45432 May 14 2017 21:31:32 ScramBlow_stRun.out 64958 1298 May 14 2017 21:19:14 ScramBlow_thRun.mac 14628 126633 May 14 2017 21:31:20 ScramBlow_thRun.out 13500 1091 May 11 2017 13:47:49 ScramBlowdown_TrDef.mac

... /AppendixA/StructuralModel:

30017 1442335 May 12 2017 20:46:41 LimStructuralMesh.inp 57853 1369 May 12 2017 14:33:46 StructuralModel.mac 33090 46477 May 14 2017 21:28:28 StructuralModel.out

... /AppendixA/ThermalModel:

54203 1478786 May 12 2017 20:45:58 LimThermalMesh.inp 11518 1251 May 12 2017 15:44:41 ThermalModel.mac 54095 49736 May 14 2017 21:28:30 ThermalModel.out

... /AppendixA/ToolboxFiles:

61043 7974 May 11 2017 18:36:45 MaterialProperties.mac 47666 7337 May 12 2017 21:46:47 dTpostProcessing.mac

... /AppendixA/Verification:

30070 2263 May 10 2017 15:21:05 vm147.inp 42505 23453 May 14 2017 21:28:26 vm147.out 57614 8534 May 10 2017 15:21:05 vm211.inp 05429 231105 May 14 2017 21:28:20 vm211.out 15528 2639 May 10 2017 15:21:05 vm227.inp 55570 44028 May 14 2017 21:28:24 vm227.out 10952 5183 May 10 2017 15:21:05 vm38.inp 10967 76457 May 14 2017 21:28:23 vm38.out Page 45

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

APPENDIX B: SIF SOLUTION TEST CASES The implementation of the SIF solution described in Section 2.1, from Reference [4], was tested to verify the implementation in the spreadsheet by reproducing Figures 10 (for tension) and 11 (for bending) of Reference [4].

The tension test case is shown in Figure B-1 and the bending test case is shown in Figure B-2. Open circles represent digitized data points from Reference [4] figures and solid lines are values calculated by the spreadsheet used in this report. The results show good agreement. The test cases are archived in the excel spreadsheet Limerick_N16D_w_Pad_LEFM_EPFM_R3.xlsm and are stored in the coldstor as described in Section 5.2 Figure B-1: Test Case for Tension (Based on Figure 10 of [4])

Page 46

Controlled Document Document No. 32-9272082-000 Limerick Unit 2 Reactor Vessel Nozzle 16D J-Groove Weld Flaw One Cycle Justification (Non-Proprietary)

Figure B-2: Test Case for Bending (Based on Figure 11 of [4])

Page 47

Attachment 8 "Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)," Document Number 32-9272081-000

Controlled Document 0402-01-F01 (Rev. 020, 11/17/2016)

CALCULATION

SUMMARY

SHEET (CSS)

Document No. 32 - 9272081 - 000 Safety Related: Yes No Title Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

PURPOSE AND

SUMMARY

OF RESULTS:

PURPOSE:

The purpose of this calculation is to justify the operation of Limerick Unit 2 with a repaired Instrumentation Nozzle (N16D) for one operating cycle.

RESULTS:

The Instrumentation Nozzle repair satisfies the applicable ASME Code requirements for one operating cycle.

If the computer software used herein is not the latest version per the EASI list, THE DOCUMENT CONTAINS AP 0402-01 requires that justification be provided.

ASSUMPTIONS THAT SHALL BE THE FOLLOWING COMPUTER CODES HAVE BEEN USED IN THIS DOCUMENT: VERIFIED PRIOR TO USE CODE/VERSION/REV CODE/VERSION/REV Yes (None)

No Page 1 of 20

Controlled Document 0402-01-F01 (Rev. 020, 11/17/2016)

Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

Review Method: Design Review (Detailed Check)

Alternate Calculation Does this document establish design or technical requirements? YES NO Does this document contain Customer Required Format? YES NO Signature Block Notes: P/R/A designates Preparer (P), Reviewer (R), Approver (A);

LP/LR designates Lead Preparer (LP), Lead Reviewer (LR);

M designates Mentor (M)

In preparing, reviewing and approving revisions, the lead preparer/reviewer/approver shall use All or All except

___ in the pages/sections reviewed/approved. All or All except ___ means that the changes and the effect of the changes on the entire document have been prepared/reviewed/approved. It does not mean that the lead preparer/reviewer/approver has prepared/reviewed/approved all the pages of the document.

Project Manager Approval of Customer References and/or Customer Formatting (N/A if not applicable)

Name Title (printed or typed) (printed or typed) Signature Date N/A N/A N/A N/A Page 2

Controlled Document 0402-01-F01 (Rev. 020, 11/17/2016)

Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

Record of Revision Revision Pages/Sections/Paragraphs No. Changed Brief Description / Change Authorization 000 All Original release; Note proprietary version is 32-9271575-000.

Page 3

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

Table of Contents Page SIGNATURE BLOCK ................................................................................................................................ 2 RECORD OF REVISION .......................................................................................................................... 3 LIST OF TABLES ..................................................................................................................................... 5 LIST OF FIGURES ................................................................................................................................... 6

1.0 INTRODUCTION

........................................................................................................................... 7 2.0 PURPOSE AND SCOPE ............................................................................................................... 7 3.0 ANALYTICAL METHODOLOGY ................................................................................................... 7 4.0 ASSUMPTIONS ............................................................................................................................ 7 4.1 Unverified Assumptions..................................................................................................................... 7 4.2 Justified Assumptions........................................................................................................................ 7 5.0 CALCULATIONS ........................................................................................................................... 8 5.1 Primary Stress Evaluation ................................................................................................................. 8 5.1.1 Loading ............................................................................................................................... 8 5.1.2 Primary Stress Calculation ................................................................................................. 9 5.2 Interference Check .......................................................................................................................... 18 5.3 Secondary and Peak Stresses ........................................................................................................ 18 5.4 Corrosion Evaluation ....................................................................................................................... 19 6.0 COMPUTER USAGE .................................................................................................................. 19

7.0 CONCLUSION

............................................................................................................................ 19

8.0 REFERENCES

............................................................................................................................ 20 Page 4

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

List of Tables Page Table 5-1: Local Piping Loads at DP 10 ................................................................................................... 8 Table 5-2: Local Piping Loads Under Service Levels at DP 10 ................................................................ 9 Table 5-3: J-groove Weld Cross-Sectional Property............................................................................... 11 Table 5-4: Stress Intensity on J-groove Weld with Level D Loads (Pressure and Piping Loads) ........... 11 Table 5-5: Stress Intensity on J-groove Weld due to Pressure Only ...................................................... 11 Table 5-6: Stress Intensity on Replacement Nozzle with Level D Loads (Pressure and Piping Loads) ................................................................................................................................... 12 Table 5-7: Stress Intensity on Replacement Nozzle due to Pressure Only ............................................ 13 Page 5

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

List of Figures Page Figure 5-1: Bore Configuration for Reinforcement Area Consideration ................................................. 16 Figure 5-2: Areas of Reinforcement ....................................................................................................... 17 Page 6

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

1.0 INTRODUCTION

The Instrumentation Nozzle (N16D) was found to be leaking at the Limerick Unit 2 plant. A half-nozzle repair is being performed.

Nozzle N16D is located in shell course #2 at the 30 ft 6 inch vessel elevation. The original nozzle is connected to the vessel wall with a partial penetration J-groove weld made on the inside of the reactor vessel (RV). The repair utilized the half-nozzle approach to modify the original nozzle. The half-nozzle approach replaces the outer portion of the existing nozzle with a new Alloy 690 nozzle and establishes a new pressure boundary on the outside surface of the RV shell with a partial penetration J-groove weld in a new Alloy 52M weld pad buildup.

The remnant of the original nozzle remains in place, along with the original J-groove weld. The original Alloy 600 nozzle and the stainless steel safe end are replaced with an Alloy 690 nozzle connected to a stainless steel reducing insert.

2.0 PURPOSE AND SCOPE This calculation justifies plant operation for one cycle with the repaired nozzle, based on the requirements of Reference [1] and the ASME Code (Reference [2]). A subsequent analysis will demonstrate acceptability of the repaired nozzle for operation beyond one cycle.

Per Reference [1], the scope of this analysis includes the modification (new weld pad, new J-groove weld, replacement nozzle) up to the terminal end of the replacement nozzle. The reducing insert as well as the fillet weld between the insert and the nozzle end is outside the scope of this analysis.

3.0 ANALYTICAL METHODOLOGY The following steps will be performed to demonstrate the acceptability of the half-nozzle repair:

• Acceptability of the new J-groove weld configuration with respect to ASME Code dimensional requirements will be determined.

• Primary stress criteria will be evaluated.

• An assessment of the secondary and peak stresses will be made, with regard to a single cycle of operation.

4.0 ASSUMPTIONS 4.1 Unverified Assumptions There is no unverified assumption used in this calculation.

4.2 Justified Assumptions

1) The repair J-groove weld is similar to the original J-groove weld in size. While the piping loads may not have resulted in significant stresses on the original J-groove weld, the loads will be applied to the repair J-groove weld through the replacement nozzle. Therefore stresses due to piping loads are evaluated for the repair J-groove weld.

2) The repair weld and replacement nozzle are subject to the same transients as the original design.

However, the original weld was on the inside surface of the vessel, while the repair weld is located on the outside surface of the vessel. As compared with the original J-groove weld location, fluid flow rate is Page 7

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary) significantly lower at the new J-groove weld location, resulting in lower heat transfer at the new J-groove weld. Therefore, the new J-groove weld will experience less severe transient thermal stresses, and the primary plus secondary stress intensity range of the repair weld is no larger than that on the original weld.

5.0 CALCULATIONS 5.1 Primary Stress Evaluation The purpose of this section is to verify the primary stress requirements for the design shown in Reference [3]. The replacement nozzle is shown in Reference [4]. The verification is based on the requirements of Reference [2] and as specified in Reference [1]. More specifically the following are included in the one cycle justification:

1) Partial penetration J-groove weld (Alloy 52M)

2) New nozzle (Alloy 690)

3) New weld pad (Alloy 52M)

4) Stresses in the vicinity of the opening (Low alloy steel, done by reinforcement check) 5.1.1 Loading The external mechanical loadings are specified in Reference [5]. The maximum internal pressure of [ ] psi occurs during the Hydrostatic Test as specified in Reference [5]. Based on Reference [5], the external loads are applied at Data Point #10 (DP 10), which is the end of the existing safe end where the reducing insert is welded.

This node is located [ ] from the surface of the existing weld buildup on the RV base metal, as shown in Reference [3]. Applicable loads from Reference [5] are collected in Table 5-1 where the direction A is the nozzle axial positive outwards, B is vertical positive up and C is determined by the right hand rule.

Table 5-1: Local Piping Loads at DP 10 Load Case FA, lbs FB, lbs FC, lbs MA, ft-lbs MB, ft-lbs MC, ft-lbs WT01 THRM03 SAMOU SEISUP SEISEM THRMFA SEISFANEW The load combinations are specified in Reference [5]. For the purpose of primary stress evaluation, the load combinations are listed as follows:

Level A and B: [

]

Level C: [ ]

Level D: [ ]

Page 8

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

Piping loads at DP 10 for different service levels are calculated conservatively as the summation of absolute values, as collected in Table 5-2 where directions x, y and z are the directions A, B and C in Table 5-1, respectively.

Table 5-2: Local Piping Loads Under Service Levels at DP 10 Service Load Fx, lbs Fy, lbs Fz, lbs Mx, in-lbs My, in-lbs Mz, in-lbs Level A&B Level C Level D 5.1.2 Primary Stress Calculation Loads listed in Table 5-2 are used to calculate stresses at locations of interest using the following equations:

( )

Axial stress: = + + (1)

Hoop stress: = ( + 1) (2)

Radial stress: = ( 1) (3)

Shear stresses: = + , = =0 (4)

where, P = maximum pressure, [ ] psig.

Ri = Cross section inner radius, in.

Ro = Cross section outer radius, in.

Mb = bending moment, in-lbs, = +

Mx = torsional moment, in-lbs Fx = axial load, lbs Fs = shear load, lbs, = +

L = moment arm distance, in.

R = distance from centroid to section at which stresses are computed, in.

I= ( ), area moment of inertia, in4.

J = 2I, polar moment of inertia, in4.

A= ( ), cross sectional area, in2.

Solving the following equation for the three principal stresses , ,  :

+ + + + + 2 + + + =0 (5)

Stress intensity (SI) is then: SI = max(l l, l l, l l).

Page 9

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

For the primary stress calculation, the level D loads are used conservatively to calculate stresses that are compared to the allowable stress values for level A (i.e., Sm for Pm, 1.5Sm for PL+Pb). The allowable stress intensity Sm for Alloy 52M and Alloy 690 at 575°F is 23.3 ksi, Reference [6]. The primary stresses are calculated at the inner radius, mean radius and outer radius. The mean radius location is used to check the primary membrane limit. The maximum stress from the outer and inner radii is used to check the primary membrane plus bending limit. The mean radius is calculated using the following equation (Ro+Ri)/2.

In the following calculation, moment arm L = [ ] (Reference [3]) is conservatively used in calculating stresses on the new J-groove weld; no moment arm is used in calculating stresses on the nozzle end as the nozzle end is the location that piping loads are determined at.

5.1.2.1 New J-Groove Weld Weld Size (NB-3352.4, Reference [2])

This weld needs to satisfy the minimum dimension requirements of FIG. NB-4244(d)-1(e) and NB-3352.4(d)(2).

With the nozzle nominal wall thickness tn = [ ] (Reference [4], the thickest among the three nozzles),

The minimum value: tc = min(0.7tn, 0.25) = min( [ ] , 0.25) = 0.25. The actual value of tc is conservatively estimated to be: [ ] > 0.25. This requirement is satisfied.

The J-groove weld depth and width shall be no less than 3/4 tn = [ ] The actual value is

[ ] minimum less [ ] of the J-groove weld, which cannot be accounted for in the structural analysis per note #16 of Reference [3]. This yields the available weld depth [ ]

minimum, or [ ] This requirement is satisfied.

The weld length along the nozzle OD shall be no less than 1.5tn = 1.5 [ ] The actual value excluding the 1/8 non-credible bottom layer is [ ]

minimum. This requirement is satisfied.

The gap between the nozzle end and the counter bore surface shall be in the range of [ ] and tn (= [ ] ). The actual value is between [ ] This requirement is satisfied.

Nozzle Diametric Clearance (NB-3337.3(a), Reference [2])

For a nozzle OD between 1 and 4 the maximum diametric clearance of 0.020 per NB-3337.3(a) is satisfied, according to Note #8 in Reference [3].

Stress Intensity (SI)

Stress intensities on the J-groove weld due to combined loads (pressure, piping loads) are calculated based on the weld throat section, with the Ri and Ro determined as follows.

Ri = (Nozzle OD)/2 Ro = [Nozzle OD +2*(fillet leg)]/2 The replacement nozzle is prepared with three sizes (Reference [4]). The corresponding cross-sectional properties of the J-groove weld are summarized in Table 5-3.

Page 10

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

Table 5-3: J-groove Weld Cross-Sectional Property Nozzle OD Ri, in. Ro, in. I, in4 J, in4 A, in2 With the Level D piping loads (Table 5-2) applied to Equations (1) to (5), considering also the pressure load, the SIs on the J-groove weld are calculated, as listed in Table 5-4.

Table 5-4: Stress Intensity on J-groove Weld with Level D Loads (Pressure and Piping Loads)

Nozzle Component stress, psi Principal stress, psi SI Location OD x y z xy 1 2 3 psi 3.40 Inside Outside Mean 3.78 Inside Outside Mean 3.94 Inside Outside Mean By Table 5-4, with Level D loads and Level A criteria, the highest primary membrane stress intensity is

[ ] < Sm (=23.3 ksi), and the highest membrane plus bending stress intensity is [ ]

< 1.5Sm (=34.95 ksi). The primary stress requirements for the J-groove weld are satisfied.

For comparison purpose, stress intensities on the J-groove due to the maximum pressure only ( [ ] psi Hydrostatic Test pressure) are listed in Table 5-5.

Table 5-5: Stress Intensity on J-groove Weld due to Pressure Only Nozzle Component stress, psi Principal stress, psi SI Location OD x y z xy 1 2 3 psi 3.40 Inside Outside Mean 3.78 Inside Outside Mean 3.94 Inside Outside Mean Page 11

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary) 5.1.2.2 New Nozzle Tentative Pressure Thickness (NB-3324.1)

For the thick portion of the nozzle,

= where Ro is the outside radius of the largest nozzle, P the Design Pressure (1250 psi)

The nozzle of larger OD is the limiting configuration for the thick portion of the nozzle. With P (1250 psi), Ro

([ ] ) and Sm (23.3 ksi), the tentative pressure thickness is 1250 x[ ]

= =[ ] .

23300 + 0.5 x 1250 The minimum nozzle wall thickness of all three sizes at the nozzle thick portion is

[ ]

For the thin portion of the nozzle,

=

where R = [ ] is the inside radius of the nozzle end, P the Design Pressure (1250 psi) 1250 x[ ]

= =[ ] .

23300 0.5 x 1250 The nozzle wall thickness of all three sizes at the nozzle thin end is

[ ]

Therefore, the tentative thickness requirement is met.

Stress Intensity (SI)

Stress intensities on the replacement nozzle due to combined loads (pressure, piping loads) are calculated based on the cross-section at the terminal end of the nozzle, with the Ri and Ro as follows. Primary stresses calculated at this location of the nozzle bounds those in other part of the nozzle.

Ri = [ ]

Ro = [ ]

With the Level D piping loads (Table 5-2) applied to Equations (1) to (5), the SIs on the replacement nozzle are calculated, as listed in Table 5-6. No moment arm is applied as the piping loads are determined for the same location.

Table 5-6: Stress Intensity on Replacement Nozzle with Level D Loads (Pressure and Piping Loads)

Component stress, psi Principal stress, psi SI Location x y z xy 1 2 3 psi Inside Outside Mean Page 12

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

By Table 5-6, with Level D loads that are significantly higher than the Level A/B loads, and with Level A criteria, the highest primary membrane stress intensity is [ ] < Sm (=23.3 ksi), and the highest membrane plus bending stress intensity is [ ] < 1.5Sm (=34.95 ksi). The primary stress requirements for the replacement nozzle are satisfied.

For comparison purpose, stress intensities on the nozzle due to the maximum pressure only ( [ ] psi Hydrostatic Test pressure) are listed in Table 5-7.

Table 5-7: Stress Intensity on Replacement Nozzle due to Pressure Only Component stress, psi Principal stress, psi SI Location x y z xy 1 2 3 psi Inside Outside Mean 5.1.2.3 Weld Pad The cross-section of the weld pad is significantly larger than the J-groove weld cross-section and it is made of an equivalent material. Since the loads are the same, no further calculation of stresses on the weld pad is needed. The primary stress requirements for the weld pad are satisfied, as the requirements are satisfied for the J-groove weld.

5.1.2.4 Calculation of Area of Reinforcement Area of reinforcement available after the repair shall be determined to comply with paragraph NB-3332.

5.1.2.4.1 Methodology

1) determine limits of reinforcement along the vessel wall

2) determine limits of reinforcement normal to the vessel wall

3) determine minimum vessel thickness using guidance of NB-3324.1

4) determine reinforcement area lost, in the corroded condition (note that the original [ ] nozzle, the original J-groove weld and buttering are all conservatively considered as the lost area).

5) determine reinforcement area lost due to counter bore into the original weld pad as results of the new repair

6) determine remaining available area of reinforcement due to difference in vessel shell designed thickness and minimum required vessel thickness (paragraph 3 above) and remanence of the original weld pad

7) determination of total area of reinforcement available after repair 5.1.2.4.2 Limits of reinforcement along the vessel wall, NB-3334.1

1) One hundred percent of the required reinforcement shall be within the greater distance from each side of the axis of the opening.

per NB-3334.1 (a)(1), Dc = D +( 2 x corr_rate x years) = [ ] = [ ] in per NB-3334.1 (a)(2), (Dc/2) + t + tn = [ ] in Page 13

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

The length of the limit of reinforcement along the vessel is [ ] in.

2) Two-thirds of the required reinforcement shall be within the greater distance from each side of the axis of the opening.

per NB-3334.1 (b)(1), ( ) + 0.5Rt = [ ] +0.5 [ ]= [ ] in per NB-3334.1 (b)(2), (Dc/2) + (2(t+tn)/3) = [ ] + (2( [ ] )/3) = [ ] in 2/3 of required reinforcement should be within the distance of [ ] in along the vessel wall. This requirement is satisfied by default since 100 percent of the reinforcement shall be located within a shorter distance of [ ] inches.

Where: Dc is corroded diameter of vessel bore of [ ] in, calculated above D is design diameter of vessel bore of [ ] in, Reference [5]

corr_rate is corrosion rate per year of [ ] in/year, Reference [7]

t is thickness of the carbon steel vessel of [ ] in, Reference [3]

tn is thickness of nozzle, nozzle thickness is not considered, therefore 0 in Ri is the vessel inside radius of [ ] in, Reference [3]

R is mean radius of vessel, R = Ri + t/2 = [ ] /2 = [ ] in 5.1.2.4.3 Limits of reinforcement normal to the vessel wall, NB-3334.2

=

2

+ 0.5 [ ]

= 0.5 + 0.5 [ ]

The limit of reinforcement in normal direction from the vessel outside diameter surface is [ ]

inches.

Where: tn is the original weld pad thickness based on the weld pad OD of [ ] This represents a nozzle configuration thickness depicted in figures NB-3338.2(a)-2 WP_OD is the original weld pad OD of [ ] , Reference [5]

Page 14

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

Dc is corroded diameter of vessel bore of [ ] in, taken from previous calculation rm is mean radius of [ ] in, calculated above ri is inside radius of corroded vessel bore taken from previous calculation (Dc/2) r2 is transition radius, the weld pad has a chamfer of [ ] , r2 radius is [ ]

inches. [ ] , Ref. [5]

5.1.2.4.4 Minimum Vessel Tentative Pressure Thickness Calculation, NB-3324.1

=

0.5

= = [ ]

Where: t is the tentative pressure thickness [in]

P is design pressure of 1250 psi, Reference [5]

R is inside vessel radius to carbon steel of [ ] in, Reference [3]

Sm is material SA-533 Gr B, Cl 1 vessel design stress intensity of 26700 psi, Reference [5]

5.1.2.4.5 Determination of reinforcement area lost due to vessel bore and alloy 600 material The reinforcement area lost is determined using SolidWorks CAD program. Areas generated using SolidWorks were verified by hand calculation. Figure 5-1 shows the bore configuration in the meridional plane that represents the appropriate section for reinforcement area considerations. Note that 40 years of corrosion was considered.

Figure 5-2 shows reinforcement area lost due to vessel bore, 40 years of corrosion and [ ] material 2

that is excluded from any reinforcement consideration. Area lost is 23.072 in . Remaining area of reinforcement due to the existing weld pad before new repair is implemented is 25.434 in2 also shown on Figure 5-2.

5.1.2.4.6 Area lost due to counter bore machined into the original weld pad The maximum counter bore depth is [ ] , Reference [3]. The counter bore maximum diameter is

[ ] , Reference [3]. The corrosion rate of [ ] , Reference [7] for assumed duration of 40 years will cause loss of thickness of [ ] = [ ] x 40 years. That will increase the counter bore depth to [ ] = [ ] , and its diameter to [ ] = [

] With consideration of the original vessel bore corroded diameter of [ ] , the area lost is [ ]

5.1.2.4.7 Excess Area of Reinforcement Available The total excess available area of reinforcement is therefore [ ]

It should be noted that part of the new added weld pad is also within the limits of reinforcement. There is no need to take credit for this new weld pad area of reinforcement since there is enough of area available from the original remaining geometry.

Page 15

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

Figure 5-1: Bore Configuration for Reinforcement Area Consideration Page 16

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

Figure 5-2: Areas of Reinforcement Note: 0.365 inches dimension is derived from the thickness of the difference between the vessel design thickness ( [ ]

in) and minimum required tentative thickness ( [ ] in)

Page 17

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary) 5.2 Interference Check There is a minimum 1/16 gap between the end of the original nozzle remnant and the replacement nozzle. A conservative calculation will be done to verify that this gap is sufficient to accommodate thermal growth, L.

Interference between the nozzle and the nozzle remnant Original Nozzle material: [ ]

Nozzle thermal expansion coefficient: noz = 8.2x10-6 in/in/°F (conservatively use Alloy 690 value at 600°F from Reference [6] for [ ])

Nozzle length: L = [ ] = [ ] (use full thickness of RV base metal, existing weld build up and new wed pad, see Reference [3])

Nozzle temperature: T = 568°F (use highest operating temperature, Reference [5])

L = L* noz* T = [ ] = [ ]

The nozzle thermal growth of [ ] is less than the minimum gap of 0.0625. The gap is sufficient to prevent interference.

Interference between the nozzle and the reducing insert Reducing insert material: SS 316L Reducing insert thermal expansion coefficient: ss = 9.8x10-6 in/in/°F (SS at 600°F from Reference [6])

Length of the nozzle end counter bore: L1 = [ ] (Reference [4])

Length of the insert within the nozzle end: L2 = [ ] (use initial minimum gap of 1/16)

With the same T = [ ] , the gap becomes L1(1+ noz*T) - L2(1+ ss*T) = [ ]

> 0. The gap is sufficient to prevent interference.

5.3 Secondary and Peak Stresses The ASME Code places a limit on secondary stresses in order to prevent failure by excessive distortion caused by the repeated application of loads. The Code also limits peak stresses, through the cumulative fatigue usage factor, in order to prevent failure by fatigue.

The repair weld and replacement nozzle are subject to the same transients as the original design. However, the original weld was on the inside surface of the vessel, while the repair weld is located on the outside surface of the vessel. As compared with the original J-groove weld location, fluid flow rate is significantly lower at the new J-groove weld location, resulting in lower heat transfer at the new J-groove weld. Therefore, the new J-groove weld will experience less severe transient thermal stresses, and the primary plus secondary stress intensity range of the repair weld is no larger than that on the original weld. The P+Q stress range due to piping loads is negligible, as the main contribution to the SI range is due to the pressure load from a comparison of values presented in Table 5-4 and Table 5-5. Secondary stresses due to hole dilation are not significantly different between the original J-groove weld and new J-groove weld. It can be concluded that the single cycle fatigue usage for the repair is 1/20 (= 2 years/40 years) of the usage as analyzed in Reference [5]. Since the usage factors in Reference

[5] are all within the limit (1.0), there is ample margin to the ASME fatigue criteria for this one cycle justification.

Page 18

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

Per Reference [5], the primary plus secondary (P+Q) stress intensity range calculated for the original nozzle was less than the allowable. The replacement nozzle end where the reducing insert is welded has the same dimensions as the original nozzle safe end. The original safe end is made of stainless steel (SS) 316L, which has the same thermal expansion coefficient as the stainless steel insert. With the replacement nozzle, the safe end is eliminated and the insert is directly welded on to the nozzle end. Since the thermal expansion coefficient of the SS insert is higher than that of the Alloy 690 nozzle, thermal stresses may develop in the nozzle at high temperature when the insert is fitted in.

The weld connecting the insert and the nozzle is evaluated in Reference [8] using NB-3600 piping criteria. The P+Q intensity range due to thermal effects is [ ] ksi (Table 8-1 in Reference [8]). The stresses in this piping analysis were based on coefficients of thermal expansion (CTEs) taken at room temperature, consistent with piping rules. The difference in CTEs between the nozzle and the insert at room temperature is 8.5x10 7.7x10-6 = 0.8x10-6 in/in/°F. However, using vessel rules, the CTEs would be taken at operating temperature.

This leads to a CTE difference of 9.8x10 8.2 x10-6 = 1.6 x10-6 in/in/°F. Considering the difference in analysis methodology between NB-3200 and NB-3600, twice the SI range (i.e., 1.6/0.8) is used as a conservative estimate of the P+Q SI range from differential thermal growth at the nozzle end. This is a conservative estimate because the piping analysis is required to use the elastic moduli (E) at room temperature, where vessel rules would use Es at operating temperature. Therefore, a conservative estimate for the stress caused by differential thermal growth is

[ ]

With the primary stresses due to pressure and piping loads as calculated in Section 5.1.2.2, the total P+Q SI range at the nozzle end may be estimated to be [ ] , which is less than the allowable 3Sm

(=3*23.3 = 69.6 ksi).

Considering a factor of 4 in peak stresses for fatigue evaluation, the magnitude of alternating stress is: Salt =

[ ] By the design fatigue curves in FIG. I-9.2.1 of Reference [9], the allowable number of cycles is over 1000. In addition to the heat up and shut down transients, SCRAM is the only transient out of Normal/Upset transients that may have some contribution to the fatigue usage. At Region B, temperature variation of SCRAM is less than half of that during heat up and shut down. Based on the design number of cycles specified in Reference [5], as the projected number of cycles, it is considered sufficient to consider one heat up and shut down cycle plus two SCRAMs for the one cycle operation. To be conservative, 6 cycles of heat up and shut down with 12 cycles of SCRAMs are considered herein. This yields the final fatigue usage factor to be [

] for the nozzle.

5.4 Corrosion Evaluation Corrosion effects have been evaluated in Reference [7] and are considered in Section 5.1.2.4 for reinforcement requirements. Corrosion has no impact on the replacement nozzle and new pad.

6.0 COMPUTER USAGE No specific engineering software is used in this calculation.

7.0 CONCLUSION

The repair of instrumentation nozzle N16D is acceptable for at least one fuel cycle of operation.

Page 19

Controlled Document Document No. 32-9272081-000 Limerick Unit 2 Instrumentation Nozzle Repair - One Cycle Justification (Non-Proprietary)

8.0 REFERENCES

1. [ ]

2. ASME Boiler and Pressure Vessel Code,Section III, Division 1, 2007 Edition, including Addenda through 2008.

3. [

]

4. [ ]

5. [

]

6. ASME Boiler and Pressure Vessel Code,Section II, Part D, 2007 Edition, including Addenda through 2008.

7. AREVA Document 51-9271544-001, Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification.

8. AREVA Document 32-9271759-000, Reducing Insert Weld to Nozzle Stress Analysis.

9. ASME Boiler and Pressure Vessel Code, Division 1 Appendices, 2007 Edition, including Addenda through 2008.

Page 20

Attachment 9 "Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)," Document Number 51-9271770-001

Controlled Document 20004-022 (03/10/2016)

AREVA Inc.

Engineering Information Record Document No.: 51 - 9271770 - 001 Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)

Page 1 of 12

Controlled Document 20004-022 (03/10/2016)

A Document No.: 51-9271770-001 AREVA Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)

Safety Related? IZJ YES D NO Does this document establish design or technical requirements? DYES IZJ NO Does this document contain assumptions requiring verification? DYES IZJ NO Does this document contain Customer Required Format? DYES IZJ NO Signature Block Pages/Sections Name and P/LP, R/LR, M, Prepared/Reviewed/

Title/Discipline Signature A-CRF, A Date Approved or Comments Andrew Kulp p All Materials Engineer II Materials Engineering t):Xy )/,e,/17 R

JJ!3-David Burak All Materials Engineer I ~-) 4-.- /1-Materials Engineering

/f,fJ~t--

Pavan Thallapragada A All Manager (/11/11 MSAU Note: P/LP designates Preparer (P), Lead Preparer (LP)

M designates Mentor (M)

R/LR designates Reviewer (R), Lead Reviewer (LR)

A-CRF designates Project Manager Approver of Customer Required Format (A-CRF)

A designates Approver/RTM- Verification of Reviewer Independence Project Manager Approval of Customer References (N/A if not applicable)

Name Title (printed or typed) (printed or typed) Signature Date David Skulina Project Manager Page 2

Controlled Document 20004-022 (03/10/2016)

Document No.: 51-9271770-001 Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)

Record of Revision Revision Pages/Sections/

No. Paragraphs Changed Brief Description / Change Authorization 000 All Original submittal; Note proprietary version is 51-9271544-000.

001 Sections 1.0 and 6.0 Updated text and Figures 1-1 and 1-2 in Section 1.0, and updated References 1 and 2 to the latest revisions.

Page 3

Controlled Document Document No.: 51-9271770-001 Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)

Table of Contents Page SIGNATURE BLOCK ................................................................................................................................ 2 RECORD OF REVISION .......................................................................................................................... 3 LIST OF FIGURES ................................................................................................................................... 5 1.0 PURPOSE..................................................................................................................................... 6 2.0 ASSUMPTIONS ............................................................................................................................ 8 2.1 Assumptions Requiring Verification................................................................................... 8 2.2 Justified Assumptions........................................................................................................ 8 3.0 CORROSION OF EXPOSED LOW ALLOY STEEL ..................................................................... 9 3.1 General Corrosion ............................................................................................................. 9 3.2 Galvanic Corrosion ............................................................................................................ 9 3.3 Crevice Corrosion............................................................................................................ 10 3.4 Stress Corrosion Cracking .............................................................................................. 10 4.0 CORROSION OF ALLOY 690 AND ALLOY 52M ....................................................................... 10

5.0 CONCLUSION

............................................................................................................................ 11

6.0 REFERENCES

............................................................................................................................ 11 Page 4

Controlled Document Document No.: 51-9271770-001 Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)

List of Figures Page Figure 1-1: Original Configuration [1,2] .................................................................................................... 7 Figure 1-2: Final Repair Configuration [1,2] ............................................................................................. 8 Page 5

Controlled Document Document No.: 51-9271770-001 Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary) 1.0 PURPOSE The repair of the N16-D reactor vessel instrumentation nozzle in the Limerick Generating Station Unit 2 (LGS-2) reactor vessel will change the penetration configuration in the following ways: 1) the repair will expose the SA-533 Grade B, Class 1 low alloy steel reactor vessel and E8018-NM low alloy steel weld pad to water conditions,

2) a new Alloy 690 nozzle will be part of the pressure boundary, and 3) a new Alloy 52M weld pad and partial penetration J-groove weld will also be part of the pressure boundary [1,2]. Also, the reducing insert to nozzle weld will now be an Alloy 52M dissimilar metal weld. The following corrosion evaluation will consider potential material degradation due to each of these changes. The original configuration and the final repair configuration are shown in Figure 1-1 and Figure 1-2, respectively. Note that the weld joining the stainless steel reducing insert (i.e., F316L) to the stainless steel pipe in the original configuration is assumed to be stainless steel because the joined base metals are both stainless steel.

Page 6

Controlled Document Document No.: 51-9271770-001 Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)

Figure 1-1: Original Configuration [1,2]

Page 7

Controlled Document Document No.: 51-9271770-001 Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)

Figure 1-2: Final Repair Configuration [1,2]

2.0 ASSUMPTIONS 2.1 Assumptions Requiring Verification There are no assumptions requiring verification.

2.2 Justified Assumptions The weld joining the stainless steel reducing insert to the stainless steel pipe in the original configuration is assumed to be stainless steel because the joined base metals are both stainless steel.

Page 8

Controlled Document Document No.: 51-9271770-001 Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary) 3.0 CORROSION OF EXPOSED LOW ALLOY STEEL The low alloy steel reactor vessel material exposed due to the repair will be in the water space environment given the elevation of the N16-D nozzle. LGS-2 implements the water chemistry control requirements of BWRVIP-190 Revision 1 to mitigate corrosion [3, 4].

3.1 General Corrosion 3.2 Galvanic Corrosion Page 9

Controlled Document Document No.: 51-9271770-001 Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)

[

]

3.3 Crevice Corrosion

[

] The environmental conditions in a crevice can become aggressive with time and can cause accelerated local corrosion.

[

]

The test results are supported by operating experience (and simulated operating experience) in light water reactors. [

]

3.4 Stress Corrosion Cracking 4.0 CORROSION OF ALLOY 690 AND ALLOY 52M Stress corrosion cracking failures of Alloy 600 and its associated weld metals (Alloy 82/182) have occurred in domestic and international light water reactors. The BWR industry addressed this issue by replacing or modifying affected materials with a modified version of Alloy 82 [9]. The modified version of Alloy 82 adds carbide stabilizers (Niobium and Titanium) to minimize chromium depletion at the grain boundaries. The PWR industry selected Alloy 690 and Alloy 52/152 as replacement materials [10]. Alloy 690 was also thermally treated to improve the microstructure, but grain boundary chromium depletion of Alloy 690/52/152 was avoided by doubling the chromium content (from ~15% to ~30%) instead of using carbide stabilizers. Alloys 690/52/152 have been in service for decades with no reported failures. Laboratory studies indicate that Alloy 690 and Alloy 52/152 have superior SCC resistance relative to the Alloy 600 and Alloy 82/182.

Page 10

Controlled Document Document No.: 51-9271770-001 Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)

Although most testing of Alloy 690/52/152 has been under PWR conditions, some studies have been performed in environments more similar to BWRs. Creviced U-bend specimens of Alloy 600 and Alloy 690 were tested at 600°F for 48 weeks with an environment of 6 ppm oxygen [11]. The Alloy 600 readily cracked, whereas Alloy 690 showed no cracking. Also, testing of Alloy 690 in high purity water containing 36 ppm oxygen at 289°C

(~550°F) for 47 weeks resulted in no cracking [11].

Extensive testing has been performed on Alloy 52/152 in high temperature deaerated water, which indicate that Alloy 52/152 is much less susceptible to SCC compared to Alloy 82/182 (the Alloy 600 weld metal) [10,12,13].

Test data of Alloy 52/152 in a high temperature oxygenated environment is not readily available, but Alloy 52/152 is expected to have a low susceptibility to SCC under these conditions as well, based on the similarity of Alloy 52/152 to Alloy 690.

The only difference between the Alloy 52M to be used in the repair and Alloy 52/152 are small alloying additions to improve weldability. The corrosion resistance is similar.

5.0 CONCLUSION

The modification of the N16-D reactor vessel nozzle at LGS-2, which will expose the low alloy steel reactor vessel to a water environment and introduce new materials (Alloy 690 and Alloy 52M), is found acceptable.

[

] Based on laboratory studies and operating experience, the replacement higher chromium content nickel-based alloys (Alloy 690 and Alloy 52M) have a high resistance to SCC.

6.0 REFERENCES

References identified with an (*) are maintained within Exelon Records System and are not retrievable from AREVA Records Management. These are acceptable references per AREVA Administrative Procedure 0402-01, . See page 2 for Project Manager Approval of customer references.

1. [ ]

2. [

]

3. [

]

4. LGS UFSAR - Appendix A, Updated Final Safety Analysis Report Supplement, Revision 18.

5. [ ]

6. D.C. Vreeland, et al., Corrosion of Carbon and Low-Alloy Steels in Out-of-Pile Boiling-Water-Reactor Environment, Corrosion, Vol. 17, No. 6, 1961.

Page 11

Controlled Document A Document No.: 51-9271770-001 AREVA Corrosion Evaluation of the Limerick Unit 2 N16-D Reactor Vessel Nozzle Modification (Non-Proprietary)

7. [

]

8. [

]

9. NUREG/CR-6923, "Expert Panel Report on Proactive Materials Degradation Assessment."

10. Materials Reliability Program (MRP):Resistance to Primmy Water Stress Corrosion Cracking ofAlloys 690, 52, and 152 in Pressurized Water Reactors (MRP-111), EPRI, Palo Alto, CA: 2004. 1009801.

11. Sedriks, A.I., Schultz, J.W., Cordovi, M.A., "Inconel Alloy 690 -A New Corrosion Resistant Material,"

Corrosion Engineering (Boshoku Gijutsu), vol. 28, pp. 82-95, 1979, Japan Society of Corrosion Engineering.

12. M. J. Psaila-Dombrowski et al., "Evaluation of Weld Metals 82, 152, 52 and Alloy 690 Stress Corrosion Cracking and Corrosion Fatigue Susceptibility," Eighth International Symposium on Environmental Degradation of Materials In Nuclear Power Systems - Water Reactors, Aug 10-14 1997, Amelia Island, FL, ANS.

13. Crum, J.R., Nagashima, T., "Review of Alloy 690 Steam Generator Studies," Eighth International Symposium on Environmental Degradation of Materials In Nuclear Power Systems - Water Reactors, Aug 10-14 1997, Amelia Island, FL, ANS.

The Vice President of Products and Engineering has approved the use of Reference 5.

Carl Fisher (Vice President of Products and Engineering)O'~ f¥ Cov \ /vi

• R;s'h,( {

Page 12