RS-16-224, Relief Request for Alternative Requirements for the Repair and Examination of Reactor Vessel Head Penetrations for the Fourth Inservice Inspection Interval

Relief Request for Alternative Requirements for the Repair and Examination of Reactor Vessel Head Penetrations for the Fourth Inservice Inspection Interval

ML16320A035
Person / Time
Site:	Byron
Issue date:	11/08/2016
From:	Gullott D Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML163320A031	List: RS-16-224, Relief Request for Alternative Requirements for the Repair and Examination of Reactor Vessel Head Penetrations for the Fourth Inservice Inspection Interval
References
RS-16-224
Download: ML16320A035 (85)

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Proprietary information contained in Attachment 3, Attachment 5 and Attachment 7 Withhold from public disclosure under 10 CFR 2.390 When separated, the cover letter, Attachment 1, Attachment 2, Attachment 4, Attachment 6 and Attachment 8 are Non-Proprietary RS-16-224 10 CFR 50.55a November 8, 2016 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Byron Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

Relief Request for Alternative Requirements for the Repair and Examination of Reactor Vessel Head Penetrations for the Fourth lnservice Inspection Interval

References:

1) Letter (RS-15-236) from D. M. Gullatt (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Requests for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds," dated September 11, 2015(ML15259A049)

2) Letter (RS-16-045) from D. M. Gullatt (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission, "Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds," dated February 11, 2016(ML16043A148)

3) Letter (RS-16-057) from D. M. Gullatt (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission, "Supplement to Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds (RS-16-045)," dated March 15, 2016 (ML16075A291)

4) Letter (RS-16-067) from D. M. Gullatt (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission, "Supplement to Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds (RS-16-045)" dated March 22, 2016(ML16082A435)

Proprietary information contained in Attachment 3, Attachment 5 and Attachment 7 Withhold from public disclosure under 10 CFR 2.390 When separated, the cover letter, Attachment 4, Attachment 6 and Attachment 8 are Non-Proprietary November 8, 2016 U.S. Nuclear Regulatory Commission Page2

5) Letter (RS-16-078) from D. M. Gullatt (Exelon Generation Company, LLC) to U.S. Nuclear Regulatory Commission, "Clarification to Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds" dated April 4, 2016 (ML16095A291)

6) Letter from Justin C. Poole (U.S. Nuclear Regulatory Commission) to Bryan C. Hanson (Exelon Generation Company, LLC), "Byron Station, Units 1 and 2 and Braidwood Station, Units 1 and 2 - Relief from the Requirements of the ASME Code (CAC Nos. MF6715, MF67156, MF6717, and MF6718)," dated April 27, 2016(ML16109A337)

7) Electric Power Research Institute Material Reliability Program: Topical Report for Primary Water Stress Corrosion Cracking Mitigation by Surface Stress Improvement (MRP-335 Revision 3)

In accordance with 10 CFR 50.55a, "Codes and standards," paragraph (z)(1), Exelon Generation Company, LLC (EGC) requests NRC approval of the attached relief request (Attachment 1) for Byron Station, Units 1 and 2; applicable for the Fourth Ten-Year Interval, lnservice Inspection (ISi) Program on the basis that the proposed alternatives would provide an acceptable level of quality and safety.

In Reference 1, EGC submitted a relief request for Braidwood Station, Units 1 and 2 and Byron Station, Units 1 and 2 applicable for the Third Ten-Year Interval ISi Program. This relief was part of a contingency effort to support repair of potential indications due to degradation of vessel head penetrations (VHPs) utilizing the AREVA Inside Diameter Temper Bead (IDTB) weld repair method. EGC supplemented the original request and responded to NRC requests in References 2, 3, 4 and 5. In Reference 6, the NRC approved the Reference 1 request to implement Relief Requests 13R-16 and 13R-28 for use of the AREVA IDTB weld repair method to restore the pressure boundary of a degraded VHP nozzle for the Third Ten-Year Interval ISi Program for Braidwood Station, Units 1 and 2 and Byron Station, Units 1 and 2.

The Attachment 1 relief request is similar to the Reference 1 relief request that was approved in Reference 6. The differences between the Attachment 1 request and the Reference 1 request are:

(1) Attachment 1 request is only applicable to Byron Station for the Fourth Ten-Year Interval ISi Program (2) Minor formatting and editorial changes are made as shown with track changes in Attachment 2 (3) The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code Section XI is updated from the 2001 Edition through 2003 Addenda to the 2007 Edition with the 2008 Addenda for the Fourth Ten-Year Interval ISi Program at Byron Station.

Proprietary information contained in Attachment 3, Attachment 5 and Attachment 7 Withhold from public disclosure under 10 CFR 2.390 When separated, the cover letter, Attachment 4, Attachment 6 and Attachment 8 are Non-Proprietary November 8, 2016 U.S. Nuclear Regulatory Commission Page 3 (4) Supporting analyses have been updated to incorporate the impact due to the addition of an upset condition transient i.e., Excessive Feedwater Transient (EFT).

Differences in the ASME Section XI Code (2001 Edition through 2003 Addenda) have been reconciled and the change to the more recent ASME Section XI Code (2007 Edition with the 2008 Addenda) had no impact on the technical basis for the proposed request.

Attachments 3, 5 and 7 contain updated analyses revised from those submitted and clarified in References 1 through 5 that include consideration of an additional operating transient, i.e., the EFT analysis. The impact due to EFT was not considered in the analyses submitted with the initial relief request for a contingency IDTB weld rotary peened repair in Reference 1. However, the upset condition transient stress due to EFT (thermal cold shock) would only occur for a short period of time, and thus the analyses were conservatively updated to include the impact due to EFT as summarized below and as provided in Attachments 3, 5 and 7. The Topical Report for Primary Water Stress Corrosion Cracking (PWSCC) mitigation by surface stress improvement (Reference 7 Section 2.3.4) states that peening applies to steady state stresses during normal operation as stress corrosion cracking initiation is a long-term process, and does not apply to transient stresses that occur only for short periods of time. As noted in Attachments 3, 5 and 7, the addition of the analysis of EFT had minor change in the results and did not impact the conclusions of the analyses as presented in References 1 through 5 and as approved in Reference 6.

The analyses were also administratively updated to identify proprietary information within brackets matching the previously provided non-proprietary versions, update references to the latest revisions, capture the change to the recent ASME Section XI Code and make minor editorial corrections and clarifications as further summarized below.

The Weld Anomaly Analysis, previously submitted in Reference 1 (AREVA Document No. 32-9237284-000, included as Attachment 2 (Proprietary) and Attachment 3 (Non-Proprietary)) was revised and is included as Attachment 3 of this request. In addition to assessing the impact of EFT, the Attachment 3 analysis identifies proprietary information using brackets, updates Linear Elastic Fracture Mechanics (LEFM) margin values, addresses a slightly larger remediated bore (as a welding contingency), updates references to the latest reference revisions and makes clarifications and minor editorial changes. The changes have no impact to the conclusions of the analysis as submitted in Reference 1.

The As-Left J-Groove Analysis previously submitted in Reference 1 (AREVA Document No. 32-9236713-000, included as Attachment 4 (Proprietary) and Attachment 5 (Non-Proprietary)) was revised and is included as Attachment 5 of this request. In addition to assessing the impact of EFT, the Attachment 5 analysis identifies proprietary information using brackets, updates references to latest reference revisions and makes clarifications and minor editorial changes. The changes have no impact to the conclusions of the analysis as submitted in Reference 1.

Proprietary information contained in Attachment 3, Attachment 5 and Attachment 7 Withhold from public disclosure under 10 CFR 2.390 When separated, the cover letter, Attachment 4, Attachment 6 and Attachment 8 are Non-Proprietary November 8, 2016 U.S. Nuclear Regulatory Commission Page4 The Life Assessment Evaluation previously submitted in Reference 4 (AREVA Document No. 51-9240805-003, Attachment 1 (Proprietary) and Attachment 2 (Non-Proprietary)) was revised and is included as Attachment 7 of this request. The Attachment 7 evaluation includes updates to the applicable operating stress and weld anomaly flaw analysis based on the inclusion of EFT. The update due to EFT insignificantly impacted the cumulative usage factor of the operating Stress analysis for the nozzle opening. Additionally, there was a minor impact to the weld anomaly flaw analysis minimum fracture toughness margins. The revision also updates references to the latest reference revisions and includes clarifications and minor editorial changes. The changes have no impact to the conclusions of the analysis as submitted in Reference 4.

The calculation of EFT is an upset condition stress and its impact to the analyses supporting this relief request is limited to those analyses that included the evaluation of operating and transient stresses. Previously submitted evaluations i.e., the PWSCC Evaluation submitted in Reference 4 (Document No. 51-9233902-002, Attachment 3 (Proprietary) and Attachment 4 (Non-Proprietary)), the Corrosion Evaluation submitted in Reference 3 (Document No. 51-9234023-002, Attachment 1 (Proprietary) and Attachment 2 (Non-Proprietary)) and the Ambient lnterpass Temperature Evaluation submitted in Reference 3 (Document No. 51-9245035-002 included as Attachment 3 (Proprietary) and Attachment 4 (Non-Proprietary)) are not impacted due to the addition of EFT.

Specifically, the PWSCC Evaluation is a flaw propagation analysis that estimates the minimum time for a PWSCC flaw to reach 75% through-wall of the original wall thickness (i.e., not a stress evaluation) and is therefore, not affected by the addition of EFT. The Corrosion Evaluation analyzes potential corrosion concerns due to the as-left bored out nozzle configuration and is not affected by the addition of EFT. The Ambient lnterpass Temperature Evaluation demonstrates that the repair weld does not require performance of direct temperature measurements prior to each weld pass and is not affected by the addition of EFT. Therefore, since the evaluation of EFT does not impact these analyses, these analyses are not included in this request.

Attachments 3, 5 and 7 contain proprietary information as defined by 10 CFR 2.390, "Public inspection, exemption, requests for withholding." AREVA, lnc,(AREVA) as the owner of the proprietary information has executed the enclosed affidavits, which identifies that the enclosed proprietary information has been handled and classified as proprietary, is customarily held in confidence, and has been withheld from public disclosure. The proprietary information was provided to EGC by AREVA as referenced by the affidavits. The proprietary information has been faithfully reproduced in the attached information such that the affidavits remain applicable.

AREVA hereby requests that the attached proprietary information be withheld, in its entirety, from public disclosure in accordance with the provisions of 10 CFR 2.390 and 10 CFR 9 .17. The affidavits supporting the proprietary nature of the information is contained in . contains the "clean" version of the Fourth Ten-Year Interval ISi Program relief request for NRC review and approval. Attachment 2 is included for information only and

Proprietary information contained in Attachment 3, Attachment 5 and Attachment 7 Withhold from public disclosure under 10 CFR 2.390 When separated, the cover letter, Attachment 4, Attachment 6 and Attachment 8 are Non-Proprietary November 8, 2016 U.S. Nuclear Regulatory Commission Page 5 contains the same Fourth Ten-Year Interval ISi Program relief request but shown with track-changes for ease of comparison of differences from the Reference 1 (Third Ten-Year Interval ISi Program) relief request that was previously approved.

The Fourth Ten-Year Interval of the Byron ISi Program began on July 16, 2016 and is scheduled to end on July 15, 2025. The attached relief request is submitted as a contingency

• and addresses potential repairs and inspections that would be performed during a refueling outage within the Fourth Ten-Year Interval and therefore, EGC requests approval of this proposed relief by February 20, 2017, prior to the beginning of the Byron Station Unit 1 refueling outage in Spring 2017 (B1R21).

There are no regulatory commitments contained within this letter.

Should you have any questions concerning this letter, please contact Ms. Jessica Krejcie at (630) 657-2816.

Respectfully, David M. Gullatt Manager - Licensing Exelon Generation Company, LLC : 10 CFR 50.55a Relief Request 14R-11, Alternative Requirements for the Repair of Reactor Vessel Head Penetrations In Accordance with 10 CFR 50.55a(z)(1)

(clean version for review and approval) : 10 CFR 50.55a Relief Request 14R-11, Alternative Requirements for the Repair of Reactor Vessel Head Penetrations In Accordance with 10 CFR 50.55a(z)(1)

(shown with track changes and included for information only) : AREVA Document #32-9237284-002, "Byron/Braidwood RVCH Nozzle IDTB Repair Weld Anomaly" (PROPRIETARY) : AREVA Document #32-9244389-001, "Byron/Braidwood RVCH Nozzle IDTB Repair Weld Anomaly" (NON-PROPRIETARY) : AREVA Document #32-9236713-003, "Byron and Braidwood RVCH Nozzle As-lett J-Groove Analysis" (PROPRIETARY) : AREVA Document #32-9244434-002, "Byron and Braidwood RVCH Nozzle As-Left J-Groove Analysis" (NON-PROPRIETARY) : AREVA Document #51-9240805-004, "Byron Units 1 & 2, and Braidwood Units 1

& 2 IDTB Reactor Vessel Head Penetration Nozzle Weld Repair-Life Assessment Summary" (PROPRIETARY)

Proprietary information contained in Attachment 3, Attachment 5 and Attachment 7 Withhold from public disclosure under 10 CFR 2.390 When separated, the cover letter, Attachment 4, Attachment 6 and Attachment 8 are Non-Proprietary November 8, 2016 U.S. Nuclear Regulatory Commission Page6 : AREVA Document #51-9252998-002, "Byron Units 1 & 2, and Braidwood Units 1

& 2 IDTB Reactor Vessel Head Penetration Nozzle Weld Repair-Life Assessment Summary" (NON-PROPRIETARY) : AREVA Inc., Affidavits for AREVA documents, Novemeber 7, 2016, September 29, 2016 and October 7, 2016

ATTACHMENT 9 AREVA Inc., Affidavit(s) for AREVA documents, November 7, 2016, September 29, 2016 and October 7, 2016

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 execµte this Affidavit.

2. I am familiar with the criteria applied by AREVA to determine whether certain AREVA information is proprietary. l 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 Calculation Summary Sheet 32-9236713-003 entitled, "Byron on Braidwood RVCH Nozzle As-Left J-Groove Analysis,"

dated November 2016 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

• • • ,4 **

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 __ ,1_-i--_h___

day of r\_(J\f\.0V\,A.-- b---vV I 2016.

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

$HERA\'(. MCFAOEN NoJtr' Pvbilc 90rlirriO!'fWQlth or Vfrgfnl*

7079129

.* My Comm111ian Expir1s Oc:t 31, 2018

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 the Calculation Summary Sheet (CSS) 32-9237284-002 entitled, "Byron/Braidwood RVCH Nozzle IDTB Repair Weld Anomaly," dated September 2016 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(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 ,_:;} 9 day of ~:~~£ e-./ , 2016.

Danita R. Kidd NOTARY PUBLIC, COMMONWEALTH OF VIRGINIA MY COMMISSION EXPIRES: 12/31/16 Reg.# 205569

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 tp 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 Engineering Information Record, 51-9240805-004, entitled, "Bryon Units 1 & 2, and Braidwood Units 1 & 2 IDTB Reactor Vessel Head Penetration Nozzle Weld Repair- Life Assessment Summary," dated October 2016 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

Ill""- -

requ_.ested 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 _=ft!>.

day of_o_~~------' 2016.

Sherry L. McFaden NOTARY PUBLIC, COMMONWEALTH OF VIRGINIA MY COMMISSION EXPIRES: 10/31/18 Reg.# 7079129 SHERRV L MCFADEN Notiry Public Pomnio.nwHlth of Virginia

. 7079129 My CommlHfCJ!'I fiXPlrl8*0cU1, 2018

ATTACHMENT 1 10 CFR 50.55a Relief Request Number Byron Station 14R-11 Request for Relief Alternative Requirements for the Repair of Reactor Vessel Head Penetrations in Accordance with 10 CFR 50.55a(z)(1)

(Clean version for review and approval)

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision O (Page 1 of 33)

Request for Relief Alternative Requirements for the Repair of Reactor Vessel Head Penetrations In Accordance with 10 CFR 50.55a(z)(1) 1.0 ASME CODE COMPONENTS AFFECTED:

Component Numbers: Units 1 and 2, Reactor Vessels 1RC01 R (Unit 1) and 2RC01 R (Unit 2)

Description:

Alternative Requirements for the Repair of Reactor Vessel Head Penetrations (VHPs) with Nozzles Having Pressure-Retaining Partial-Penetration J-groove Welds Code Class: Class 1 Examination Category: ASME Code Case N-729-1 Code Item: 84.20 Identification: Units 1 and 2, VHP Numbers 1 through 78, (P-1 through P-

78) - Except VHPs with Previous Repairs Previous repairs: Unit 2, P-6 and P-68 and Unit 1, P-31, P-43, P-64 and P-76 Reference Drawing: Closure Head Assembly 185282E Size: 4 Inch Nominal Outside Diameter Material lnconel Alloy 600 (SB-167) 2.0 APPLICABLE CODE EDITION AND ADDENDA:

Interval lnservice Inspection (ISi) and Repair/Replacement Programs: American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, 2007 Edition with the 2008 Addenda. Examinations of the VHPs are performed in accordance with 10CFR50.55a(g)(6)(ii)(D), which specifies the use of Code Case N-729-1, with conditions.

Code of Construction [Reactor Pressure Vessel (RPV)]: ASME Section Ill, 1971 Edition through Summer 1973 Addenda.

3.0 APPLICABLE CODE REQUIREMENT:

The applicable requirements of the following Construction Codes for the removal or mitigation of defects from which relief is requested are as follows:

ASME Code.Section XI. 2007 Edition with 2008 Addenda

• IWB-3420 states:

Each detected flaw or group of flaws shall be characterized by the rules of IWA-3300 to establish the dimensions of the flaws. These dimensions shall be used in conjunction with the acceptance standards of IWB-3500.

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 2 of 33)

• IWB-3132.3 states:

A component whose volumetric or surface examination detects flaws that exceed the acceptance standards of Table IWB-3410-1 is acceptable for continued service without a repair/replacement activity if an analytical evaluation, as described in IWB-3600, meets the acceptance criteria of IWB-3600. The area containing the flaw shall be subsequently reexamined in accordance with IWB-2420(b) and (c).

ASME Code, Section Ill, 2001 Edition, including Addenda through 2003

• NB-5245, Butt-Welded Nozzles or Branch Connections, specifies progressive surface examination of partial penetration welds.

• NB-5331 (b) states:

Indications characterized as cracks, lack of fusion, or incomplete penetration are unacceptable regardless of length.

Code Case N-638-4, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique, provides requirements for automatic or machine gas tungsten arc welding (GT AW) of Class 1 components without the use of preheat or post weld heat treatment.

• Paragraph 1(g) states:

Peening may be used, except on the initial and final layers.

The applicable requirements of the following Construction Codes for the removal or mitigation of defects from which relief is not specifically requested are as follows:

ASME Code,Section XI, 2007 Edition with 2008 Addenda

• IWA-3300 specifies requirements for characterization of flaws detected by inservice examination.

• IWA-4221 (b) states:

An item to be used for repair/replacement activities shall meet the Construction Code specified in accordance with (1 ), (2) or (3) below.

• IWA-4221(c) states in part:

As an alternative to (b) above, the item may meet all or portions of the requirements of different Editions and Addenda of the Construction Code, or Section Ill ...

provided the requirements of IWA-4222 through IWA-4226, as applicable, are met ...

• IWA-4224.1, Identical material Procured to a Later Edition or Addenda of the Construction Code, Section Ill or Material Specification.

(a) Materials, including welding materials may meet the requirements of later dates ...

(b) Differences in the specified material tensile stress ...

• IWA-4400 provides welding, brazing, metal removal, fabrication, and installation requirements related to repair/replacement activities.

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision O (Page 3 of 33)

• IWA-4411 states:

Welding, brazing, fabrication, and installation shall be performed in accordance with the Owner's Requirements and, except as modified below, in accordance with the Construction Code of the item.

• IWA-4411 (a) states in part:

Later editions and addenda of the Construction Code, or a later different Construction Code, either in its entirety or portions thereof, and Code Cases may be used, provided the substitution is as listed in IWA-4221 (c). Filler metal requirements shall be reconciled, as required, in accordance with IWA-4224.

• IWA-4412 states:

Defect removal shall be accomplished in accordance with the requirements of IWA-4420.

• IWA-4420(a) states:

Defect removal by mechanical processing shall be in accordance with IWA-4462.

• IWA-4462(b) states:

Where welding is to be performed, the cavity shall be ground smooth and clean with beveled sides and edges rounded to provide suitable accessibility for welding.

• IWA-4611.1 (a) states:

Defects shall be removed in accordance with IWA-4422.1. A defect is considered removed when it has been reduced to an acceptable size.

ASME Code. Section Ill. 1971 Edition. including Addenda through 1973

• Table NB-4622.1-1 requires:

Post Weld Heat Treatment (PWHT) for P3 materials.

Code Case N-729-1, Alternative Examination Requirements for PWR Reactor Vessel Upper Heads with Nozzles Having Pressure-Retaining Partial-Penetration Welds,Section XI, Division 1, Fig. 2, "Examination Volume for Nozzle Base Metal and Examination Area for Weld and Nozzle Base Metal", is applicable to the VHPs.

Code Case N-749, Alternative Acceptance Criteria for Flaws in Ferritic Steel Components Operating in the Upper Shelf Temperature Range,Section XI, Division 1 4.0 REASON FOR REQUEST:

To ensure timely repair and minimize impact on NRC resource's on an emergent basis, a preemptive submittal of this relief request is being made as a contingency effort to support the required repair for potential indication(s) discovered in upcoming outages for the Fourth lnservice Inspection Interval. If an indication requiring repair was detected during an ISi Program ultrasonic (UT) examination of the VHPs, the affected VHP(s) will be modified under this request.

Because of the risk of damage to the RVCH material properties or dimensions, it is not feasible to apply the post weld heat treatment (PWHT) requirements of the original

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision O (Page 4 of 33)

Construction Code. As an alternative to the requirements of RVCH Code of Construction, Exelon proposes to perform the modification of the VHP(s) utilizing the Inside Diameter Temper Bead (IDTB) welding method to restore the pressure boundary of the degraded nozzle penetration. The IDTB welding method is performed with a remotely operated weld tool utilizing the machine gas tungsten arc welding (GT AW) process and the ambient temperature temper bead method with 50° F minimum preheat temperature and no PWHT. The modification described below will be performed in accordance with the 2007 Edition with 2008 Addenda of ASME Section XI, Code Case N-638-4, Code Case N-729-1, and the alternatives discussed in 5.0.

Basic steps for the modification are:

1) Removal of a lower portion of the existing thermal sleeve assembly at the applicable VHP(s) to provide access for IDTB welding.

2) Roll expansion above the region to be modified to stabilize the nozzle and prevent any movement when the nozzle is separated from the nozzle to RVCH J-groove weld.

3) Machining to remove the lower nozzle (and CETC nozzle guide at CETC nozzle locations) to an elevation above the J-groove weld eliminating the portions of the nozzle which may contain the unacceptable indication(s). This machining operation also establishes the weld prep area (Refer to Figures A-1 and A-10).

4) Liquid penetrant (PT) examination of the machined area (Refer to Figures A-3 and A-12).

5) Welding the remaining portion of the nozzle, and replacement CETC nozzle extension at the applicable VHP(s), to the RVCH using primary water stress corrosion cracking (PWSCC) resistant Alloy 52/Alloy 52M/Alloy 52MSS, hereinafter all referred to as Alloy 52, weld material (Refer to Figures A-2 and A-11).

6) Machining the weld and nozzle to provide a surface suitable for nondestructive examination (NOE).

7) PT and UT examination of the weld and adjacent region (Refer to Figures A-3 and A-12).

8) Rotary peening on the portion of the remaining nozzle most susceptible to PWSCC to impart compressive residual stress on the nozzle surface.

9) PT examination of the peened area.

10) Welding of a new lower thermal sleeve assembly at the applicable VHP(s) and I or installation of a CETC nozzle guide at the CETC nozzle locations.

Note the figures in this request are provided to assist in clarifying the above description.

The location of the VHP nozzle welds relative to the inner and outer spherical radii of the RVCH, and the existing J-groove weld will vary depending upon the location of the VHP nozzle and as-found dimensions.

Exelon has determined that modification of the VHP(s) utilizing the alternatives specified in this request will provide an acceptable level of quality and safety. Relief is requested in accordance with 10 CFR 50.55a(z)(1 ).

IS/ Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 5 of 33) 5.0 PROPOSED ALTERNATIVE AND BASIS FOR USE:

5.1 IDTB Modification Acceptance Examination ASME Section Ill, 2001 Edition, including Addenda through 2003, NB-5245, specifies progressive surface examination of partial penetration welds. The original Construction Code requirement for progressive surface (PT) examination, in lieu of volumetric examination, was because volumetric examination is not practical for the conventional partial penetration weld configurations. Therefore, the following combination of UT and PT examinations are proposed.

For a CROM and RVLIS nozzle repair/modification, the welds are suitable for UT examination. However, the welds are only accessible from the top side, and therefore limited UT coverage of the volume within the lower taper transition is available as discussed herein (Refer to Figures A-4 thru A-8). For a CETC nozzle repair/modification, the weld is.suitable for UT examination and the weld is accessible from both the top and bottom sides (Refer to Figures A-13 thru A-17).

UT volumetric examination of the repaired/modified configuration will be performed as specified in ASME Code Case N-638-4, 4(a)(2) and 4(a)(4). The acceptance criteria of NB-5330, in ASME Section Ill, 2001 Edition, including Addenda through 2003, apply to all flaws identified within the repaired/modified volume. Regulatory Guide 1.147, Rev.

17, has conditionally approved Code Case N-638-4 with the condition that UT volumetric examinations are performed with personnel and procedures qualified for the repaired volume and qualified by demonstration using representative samples which contain construction type flaws (see 7.1).

The UT transducers and delivery tooling are capable of scanning from cylindrical surfaces with inside diameters of approximately 2.75 in. The scanning is performed using 0° L-wave transducers, 45° L-wave transducers in two opposed axial directions, and 70° L-wave transducers in two opposed axial directions as well as 45° L-wave transducers in two opposed circumferential directions. Additionally, the low alloy steel extending to Xi in. beneath the weld into the low alloy steel base material (see Figures A-3 and A-12) will be examined using the 0° L-wave transducers searching for evidence of under bead cracking and lack of fusion in the heat affected zone.

The UT equipment is not capable of scanning from the face of the weld taper at CROM and RVLIS nozzle locations. The 45°L and 70°L axial UT examination scans looking down (see Figures A-5 and A-7) will interrogate the taper transition volume on the CROM and RVLIS nozzle welds. Approximately 70% of the CROM and RVLIS nozzle weld surface is expected to be scanned by UT. Approximately 83% of the RVCH ferritic steel heat affected zone is expected to be covered by UT. The actual CROM and RVLIS nozzle volume examined will be calculated after the as-built dimensions of the weld are known and the examination is performed. It is anticipated that greater than 80% of the examination volume will obtain two-directional coverage for the CROM and RVLIS nozzle modified configuration. There is no portion of the CROM or RVLIS nozzle weld volume that does not receive at least single direction UT coverage. The UT coverage of the modified CETC nozzle configuration will exceed the coverage of the CROM and RVLIS nozzle modified configuration since it receives essentially 100% coverage. The UT examination coverage volumes are shown in Figures A-4 through A-8 for CROM and RVLIS nozzle scans and A-13 through A-17 for CETC nozzle scans.

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision O (Page 6 of 33)

In addition to the UT examinations, a final surface PT examination will be performed on the entire weld as shown in Figure A-3 for the CROM and RVLIS nozzle welds and Figure A-12 for the CETC nozzle welds. PT examination will also be repeated on the remediated surfaces. Further, the volume in question will be examined to the extent practical using the 70°L and 45°L (see Figures A-5, A-7, A-14, and A-16) axial UT examination scans (looking down). There is no portion of the repair that does not receive surface liquid penetrant examination and at least single-direction UT coverage of the volume. The final examination of the new weld and immediate surrounding region will be sufficient to verify that defects have not been induced in the ferritic low alloy steel RVCH base material, due to the welding, to the extent practical.

The combination of performing PT and UT examinations depicted in Figures A-3 and A-12 during the IOTB repair provides assurance of structural integrity. Thus, EGC requests relief from the progressive surface examination requirements specified in NB-5245.

5.2 Triple Point Anomaly ASME Section Ill, 2001 Edition, including Addenda through 2003, NB-5331 (b) states:

Indications characterized as cracks, lack of fusion, or incomplete penetration are unacceptable regardless of length.

An artifact of ambient temperature temper bead welding is an anomaly in the weld at the triple point. The triple point is the point in the repair weld where the low alloy steel RVCH base material, the Alloy 600 nozzle, and the Alloy 52 weld intersect. The location of the triple point for the CROM and RVLIS nozzle is shown in Figure A-2 and the upper and lower triple points for the CETC nozzle are shown in Figure A-11.

This anomaly consists of an irregularly shaped very small void. Mock-up testing has verified that the anomalies are common and do not exceed 0.10 in. in length and are assumed to exist, for purposes of analysis, around the entire bore circumference at the triple point elevation.

A fracture mechanics analysis [9] has been performed for the design configuration to provide justification, in accordance with Section XI, for operating with the postulated triple point anomaly. The anomaly is modeled as a 0.10 in. deep crack-like defect, initiating at the triple point location, considering the most susceptible material for propagation. Postulated flaws could be oriented within the anomaly such that there are two possible flaw propagation paths, as discussed below.

Path 1: Flaw propagation is across the nozzle wall thickness from the outside surface to the inside surface of the nozzle.

This is also the shortest path through the new Alloy 52 weld material. By using a fatigue crack growth rate twice that of the rate of Alloy 600 material, it is ensured that another potential path through the heat affected zone between the new weld and the Alloy 600 nozzle material is also bounded.

For completeness, two types of flaws are postulated at the outside surface of the nozzle new IOTB weld. A 360-degree continuous circumferential flaw, lying in a horizontal plane, is considered to be a conservative representation of crack-like defects that may exist in the weld triple point anomaly. This flaw is

/SI Program Plan Units 1 & 2, Fourth /nteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 7 of 33) subjected to axial stresses in the nozzle. An axially oriented semi-circular outside surface flaw is also considered since it would lie in a plane normal to the higher circumferential stresses. Both of these flaws would propagate toward the inside surface of the nozzle when subjected to high cyclic stresses in the nozzle penetration repair.

Path 2: Flaw propagation extends down the outside surface of the repair weld between the weld and the RVCH.

A cylindrically oriented flaw is postulated to lie along this interface, subjected to radial stresses with respect to the nozzle. This flaw may propagate through either the new Alloy 52 weld material or the ferritic low alloy steel RVCH base material.

The results of the analyses demonstrate that the 0.1 O in. weld anomaly is acceptable for a 40-year design life of the nozzle modification considering the applicable transients and cycles. Sufficient design margins are demonstrated for all flaw propagation paths considered in the analysis. Flaw acceptance is based on criteria for limit load (IWB-3644). Fatigue crack growth is conducted along each flaw propagation paths for the CROM, RVLIS and CETC nozzles. For the postulated axial and circumferential flaws in the Alloy 52 repair weld, the acceptance criteria of IWB-3642 which permits the use of the analytical procedures described in ASME Section XI, Appendix C. For the CROM, RVLIS, and CETC nozzle welds, net section collapse analysis is performed for the postulated circumferential flaw. Cross-sectional bending at the postulated flaw locations is insignificant due to the nozzle being encased in the vessel head. The limit load failure is driven by applied membrane stresses and evaluated. The allowable bending stress is shown to be more than the applied bending stress. Also, the minimum limit load margins for postulated axial and cylindrical flaws are less than the required safety factor of 2. 7, as specified in IWB-3644. For the cylindrical flaws, it is shown that the applied shear stress at the remaining ligament is less than the allowable shear stress per NB-3227.2.

These evaluations are prepared in accordance with ASME Section XI and demonstrate for the intended service life of the modification that the fatigue crack growth is acceptable and the crack-like indications remain stable. This satisfies the ASME Section XI criteria but does not include considerations of stress corrosion cracking such as PWSCC. Since the postulated crack-like defects at the top of the CROM nozzle weld(s),

RVLIS nozzle weld(s) and CETC nozzle weld(s) due to the weld anomaly are not exposed to the primary coolant and the air environment is benign for the materials at the triple point, the crack growth rates from PWSCC are not applicable.

EGC requests relief from the acceptance criteria specified in NB-5331 (b) to permit anomalies, as described herein, at the triple point region to remain in service.

5.3 Flaw Characterization and Successive Examinations - RVCH Original J-Groove Weld The assumptions of IWB-3600 are that cracks are fully characterized in order to compare the calculated parameters to the acceptable parameters addressed in IWB-3500. There are no qualified UT examination techniques for examining the original nozzle-to-RVCH J-groove welds. Therefore, since it is impractical to characterize the flaw geometry that may exist therein, it is conservatively assumed the "as-left" condition of the remaining J-groove weld includes flaws extending through the entire Alloy 82/Alloy

ISi Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 8 of 33) 182 J-groove weld and buttering. It is further postulated that the dominant hoop stresses in the J-groove weld would create a situation where the preferential direction for cracking would be radial. A radial crack in the Alloy 82/Alloy 182 weld would propagate by PWSCC, through the weld and buttering, to the interface with the low alloy steel RVCH material. Any growth of the postulated "as-left" flaw into the low alloy steel would be by fatigue crack growth under cyclic loading conditions.

The J-groove flaws have been evaluated using worst-case postulated flaw sizes.

Fatigue crack growth for cyclic loading conditions using operational stresses from pressure and thermal loads and crack growth rates from Article A-4300 of Section XI for ferritic material in a primary water environment will be calculated. The results of this evaluation show that, based on a combination of linear elastic fracture mechanics (LEFM) analysis and elastic-plastic fracture mechanics (EPFM) analysis [1 O] of a postulated remaining flaw in the original Alloy 82/Alloy 182 J- groove weld and buttering for the modified RVCH nozzle is acceptable for the remaining life of the Unit plus a 20 year life extension following an IDTB weld repair.

LEFM and EPFM analyses [1 O] were used to demonstrate the remaining service life plus life extension for the remaining worst-case "as-left" flaw in the J-groove weld. Although the postulated flaw did not satisfy ASME Code Section XI IWB-3612 for all transient loading conditions, LEFM analysis:

• determined that the uphill side of the VHP penetration is the worst case position for the postulated flaw,

• calculated the final flaw size by fatigue crack growth, and

• identified the controlling service conditions for evaluation by EPFM analysis.

Crack stress intensity factors for initial "as-left" flaws are first determined using 3-dimensional finite element analysis and applying both residual and operating stresses for each of the applicable transients. Crack size is incremented based on the fatigue crack growth rate equations given in A-4300 of ASME Section XI, as modified by 10CFR50.55a. For the VHP nozzle welds the maximum flaw growth into the RVCH low alloy steel is calculated on the uphill side and on the downhill side and the remaining service life determined. The crack stress intensity factor, including pressure, thermal and residual stress effects, for the final maximum flaw size using the acceptance criteria of IWB-3612 indicated insufficient available fracture toughness to provide the specified margins under all conditions, thus, the appropriate failure mechanism (ductile tearing) was determined below.

Based on a determination that ductile tearing is the failure mechanism for the final flaw under the conditions being evaluated, EPFM analysis is utilized to evaluate the final flaw sizes for all propagation paths. EPFM analysis is performed using a J-integral/tearing modulus (J-T) diagram to evaluate flaw stability under ductile tearing. Additionally, the crack driving force (applied J-integral) is checked against the J-R curve at a crack extension of 0.10 in. (J0.1 ). The safety factors that are applied to the primary and secondary stresses in the EPFM analysis are tabulated below:

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision O (Page 9 of 33)

Safety Factors*

Operating Condition Evaluation Method Primary Secondary Normal/Upset JIT based flaw stability 2.14 1.0 Normal/Upset J0.1 limited flaw extension 1.5 1.0 Emergency/Faulted J/T based flaw stability 1.2 1.0 Emergency/Faulted J0.1 limited flaw extension 1.25 1.0

• EPFM safety factors from Code Case N-749 as modified by the NRC (see attachment in ML14330A510).

The potential for debris from a cracking J-groove partial penetration weld was considered. Radial cracks were postulated to occur in the weld due to the dominance of hoop stresses at this location. This possibility of occurrence of transverse cracks that could intersect the radial cracks is considered remote. There are no forces that would drive a transverse crack. The radial cracks would relieve the potential transverse crack driving forces. The conclusion is that there are no known service conditions that could drive radial cracks and transverse cracks to intersect to produce a loose part.

Flaws are postulated to exist in the remaining portion of the J-groove weld and shown in the evaluation to be acceptable for 33 years of remaining operation (based on a 60 year plant licensed life).

Successive examinations required by IWB-3132.3 will not be performed because analytical evaluation of the worst-case postulated flaw is performed to demonstrate acceptability. A reasonable assurance of the RVCH structural integrity is maintained without the successive examinations.

EGC requests relief from flaw characterization specified in IWB-3420 and subsequent examination requirements specified in IWB-2420(b) and IWB-2420(c).

5.4 Rotary Peening Rotary peening is performed on the final layer to provide further assurance of the modified configuration being resistant to PWSCC [11]. However, peening on the final layer of a temper bead weld is prohibited by ASME Code Case N-638-4, 1(g). This prohibition is referring to the high cold-work peening that is traditionally used for configuration distortion control during welding, as was interpreted by ASME Xl-1-13-19 for Code Case N-606-1 [14]. This is not considered applicable to the rotary peening process, which is highly controlled, uniform, and only influences a shallow surface layer (approximately 20 mils at the base metal i.e., bounding depth). The uniform compressive stress layer created by the rotary peening process does not inhibit subsequent NOE. Furthermore, this residual compressive stress layer has been shown to greatly reduce PWSCC initiation.

ASME Code Section 111, Appendix W, W-2140, clearly describes the beneficial nature of compressive stresses for the mitigation of stress corrosion cracking (SCC) susceptibility.

It states that shot peening, as a form of stress improvement, can be used to place the inside diameter of piping in a compressive residual stress state to resist SCC. Extensive laboratory testing performed as part of MRP-61 indicates that shot peening successfully

/SI Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision O (Page 10 of 33) inhibits PWSCC initiation. With rotary peening, the shot is captured in a flap and regularly spaced such that it uniformly imparts compressive stresses on metal surfaces.

However, the additional benefits of rotary peening regarding increased PWSCC resistance will not influence the inspection frequency for the modified nozzles as depicted in Code Case N-729-1 .

EGC requests relief from Code Case N-638-4, 1(g).

5.5 Preservice Inspection {PSI) and lnservice Inspection (ISi) of VHPs Repaired as shown in Figures A-9 and A-18 Examination PSI/ISi Parts Requirement I Examination Acceptance Extent I Examined Figure Method Standard Frequency All nozzles, each CROM/RVLIS Fig. A-9 Surface N-729-1, -3130 refueling outage All nozzles, each CETC Fig. A-18 Volumetric N-729-1, -3130 refueling outage Code Case (CC) N-729-1 provides requirements for the inspection of VHPs with nozzles having partial penetration welds. CC N-729-1Table1, Item 84.20, permits either volumetric or surface examination. Item 84.20 examination requirements are specified in Figure 2 of CC N-729-1. Since either volumetric or surface examination is acceptable, surface examination will be used for PSI/ISi for repaired CROM and RVLIS nozzles as shown in Figure A-9 due to limited tooling access and volumetric examination will be used for PSI/ISi for repaired CETC nozzles as shown in Figure A-18 (see 7.2).

The repair/modification proposed by this relief request removes much of the examination area depicted in figure 2 of CC N-729-1 at several locations. Thus, Figure A-9 of this relief request is used to establish the examination area of a repaired CROM or RVLIS nozzle for the preservice inspection following repair and for future inservice inspections.

Similarly, Figure A-18 of this relief request is used to establish the examination area of a repaired CETC nozzle for the preservice inspection following repair and for future inservice inspections. The established examination areas are equivalent to that required by Figure 2 in CC N-729-1; as it examines the nozzle weld and the same area above the CROM nozzle weld, RVLIS nozzle weld, CETC nozzle weld and the CETC nozzle base material below the weld as would be required by Figure 2 in the Code Case.

Therefore, preservice inspection following repair and future inservice inspections will comply with Code Case N-729-1 as modified by 10 CFR 50.55a(g)(6)(ii)(O) and as depicted in Figures A-9 and A-18.

5.6 General Corrosion Impact on Exposed Low Alloy Steel The IOTB nozzle modification leaves a small portion of low alloy steel in the RVCH exposed to primary coolant. An evaluation [12] was performed for the potential corrosion concerns at the RVCH low alloy steel wetted surface. Galvanic corrosion, hydrogen embrittlement, sec, and crevice corrosion are not expected to be a concern for the exposed low alloy steel base metal. General corrosion of the exposed low alloy steel base metal will occur in the area between the IDTB weld and the original J-groove

IS/ Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 11 of 33) weld. The general corrosion rate is conservatively estimated to be 0.0036 in./year. The corrosion of the exposed base metal has negligible impact on the RVCH and is acceptable for 40 years from the time the modification is performed.

5.7 Conclusions Implementation of an IDTB repair to the VHP(s) will produce an effective repair that will restore and maintain the pressure boundary integrity of the VHPs. Similar modifications have been performed successfully and have been in service for several years without any known degradation (e.g., Shearon Harris, Palisades). This alternative provides improved structural integrity and reduced likelihood of leakage for the primary system.

Accordingly, the use of the alternative provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1).

6.0 DURATION OF PROPOSED ALTERNATIVES The analyses of the modified configurations described herein and others for the modified configuration that will be implemented under 10 CFR 50.59 support the remaining life of the original 40 year plant design life plus License renewal life (20 years) of a new 60 year plant design life [13]. The analysis results are based upon expected repair parameters which may vary during implementation. The design lifetime is sensitive to the vertical length of the Alloy 52 weld ligament and the actual limiting ligament length may vary depending upon the as-found and "as-left" conditions. The design life will be re-evaluated if necessary using as-built data and incorporated into the modification, future NOE schedules, and asset management plans. All repaired RVCH penetration nozzles will be examined in accordance with ASME Code Case N-729-1 as conditioned by 10CFR50.55a(g)(6)(ii)(D). The periodic examinations will provide reasonable assurance of the structural integrity of RVCH nozzles prior to exceeding the design life of the repair.

The life of the repair is based on the as-left J-Groove flaw evaluation. A combination of linear elastic and elastic-plastic fracture mechanics, show the postulated flaws to be acceptable for 33 years of remaining operation utilizing the appropriate safety factors and the lower bound J-R curve from Reg. Guide 1.161 [1 O]. The results of the weld anomaly flaw evaluation demonstrated that a 0.1 O" weld anomaly is acceptable for 40 years of plant life (after a repair) [9]. The estimated minimum time for a PWSCC flaw to propagate through 75% of the original wall thickness is over 100 EFPY utilizing rotary peening surface remediation. The overall acceptable life of the repair design is based on the most limiting life predicted amongst the weld anomaly analysis [9], the as-left J-groove analysis [1 O] and the PWSCC evaluation [11] of the original Alloy 600 nozzle, which is acceptable for the remaining life of a 60 year plant license.

The provisions of this relief request are applicable for the Fourth lnservice Inspection Interval for Byron Station Units 1 and 2, currently scheduled to end on July 15, 2025.

The modification installed in accordance with the provisions of this relief shall remain in place for the design life of the modification, until another alternative is approved by the NRC, or until the RVCH is replaced.

IS/ Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision O (Page 12 of 33) 7.0 ADDITIONAL INFORMATION 7.1 VHP Weld Qualification Mockup UT Acceptance AREVA, in support of many similar modifications, has performed many qualifications using mockups since VHP modifications at Oconee Nuclear Station in 2001. During these evolutions, the site crew performs training on mockups for each of their respective specialties, i.e., machinists train on machining mockups, welders train on welding mockups, and NOE personnel train on NOE mockups.

UT is required by Code Case N-638-4. NRC Reg. Guide 1.147, Rev. 17 imposes a condition for this code case that requires the examination procedure and examination personnel be qualified by demonstration on representative samples which contain construction type flaws. To satisfy this requirement a mockup containing reflectors to simulate construction type flaws applicable to this weld process has been used. A NiCrFe alloy calibration block is used and contains a series of electrical-discharge machining (EDM) notches at nominal depths of 10%, 25%, 50%, and 75% deep from both inside diameter and outside diameter surfaces in both the axial and circumferential orientation. The block also contains 1/4T, 1/2T, and 3/4T deep end holes and side drilled holes that are used for calibration.

The examination procedure has also demonstrated the ability to detect a linear weld fabrication triple point anomaly extending 0.10 in. into the weld. The examination procedure was used to collect automated data for the demonstration. An IDTB weld NOE mockup was fabricated to replicate the expected configuration. It contains a series

• of EDM notches at the triple point to simulate the triple point anomaly at various depths into the nozzle wall and cracking at the IDTB weld to low alloy steel interface. It also contains flat bottom holes drilled from the mockup outside diameter so that the hole is normal to the surface to simulate under bead cracking, lack of bond, and lack of fusion.

This is the same mockup used for the procedure qualification for the Davis Besse and Shearon Harris VHP nozzle modifications listed in Section 8.0.

7.2 CETC Nozzle Weld Qualification Mockup UT PSI/ISi The UT examination of the modified configuration has been qualified by demonstration as required by 10CFR50.55a(g)(6)(ii)(D)(4) on a similar mockup configuration that represents the nozzle modification.

8.0 PRECEDENTS

1. Davis-Besse Nuclear Power Station - Relief Request RR-A34, April 1, 2010, ADAMS Accession Number ML100960276

2. Shearon Harris Nuclear Power Plant, Unit 1 - Relief Request 13R-09, October 2, 2012, ADAMS Accession Number ML12270A258

3. Shearon Harris Nuclear Power Plant, Unit 1 - Relief Request 13R-11, September 13, 2013, ADAMS Accession Number ML13238A154

4. Shearon Harris Nuclear Power Plant, Unit 1 - Relief Request 13R-13, November 22, 2013, ADAMS Accession Number ML13329A354

/SI Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 13 of 33)

5. Shearon Harris Nuclear Power Plant, Unit 1 - Relief Request 13R-15, April 29, 2015, ADAMS Accession Number ML15120A406

9.0 REFERENCES

1. ASME Code Case N-638-4 Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique,Section XI, Division 1.

2. NRC Regulatory Guide 1.147, Revision 17, lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1

3. ASME Code Case N-729-1 Alternative Examination Requirements for PWR Reactor Vessel Upper Heads With Nozzles Having Pressure-Retaining Partial-Penetration Welds,Section XI, Division 1

4. Materials Reliability Program: An Assessment of the Control Rod Drive Mechanism (CROM) Alloy 600 Reactor Vessel Head Penetration PWSCC Remedial Techniques (MRP-61), EPRI, Palo Alto, CA: 2003. 1008901.

5. ASME Code Case N-749 Alternative Acceptance Criteria for Flaws in Ferritic Steel Components Operating in the Upper Shelf Temperature Range,Section XI, Division 1

6. Byron Station Unit 1 - Relief Request 13R-19, February 1, 2012, ADAMS Accession Number ML112990783

7. Byron Station Unit 2 - Relief Request 13R-14, May 23, 2007, ADAMS Accession Number ML071290011

8. Byron Station Unit 2 (13R-20) and Braidwood Station (13R-09), March 29, 2012, ADAMS Accession Number ML120790647

9. AREVA Calculation #32-9237284-002, "Byron/Braidwood RVCH Nozzle IDTB Repair Weld Anomaly" (Proprietary)

10. AREVA Calculation #32-9236713-003, "Byron and Braidwood RVCH Nozzle As-Left J-Groove Analysis" (Proprietary)

11. AREVA Calculation #51-9233902-002, "PWSCC Evaluation for Contingency RVCH Nozzle Repairs at Byron Unit 1 and 2 and Braidwood Units 1 and 2" (Proprietary)

12. AREVA Calculation #51-9234023-002, "Corrosion Evaluation of Byron Units 1 and 2 and Braidwood Units 1 and 2 IDTB Weld Repairs" (Proprietary)

13. AREVA Calculation #51-9240805-004, "Byron Units 1 & 2, and Braidwood Units 1

& 2 IDTB Reactor Vessel Head Penetration Nozzle Weld Repair-Life Assessment Summary" (Proprietary)

14. ASME Boiler and Pressure Vessel Code,Section XI, Interpretation Xl-1-13-19, File No. 13-56, Code Case N-606-1, June 21, 2013

15. Letter (RS-15-236) from D. M. Gullatt (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "Requests for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds," dated September 11, 2015 (ML15259A049)

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 14 of 33)

16. Email from J. Wiebe (NRC) to J. Krejcie (Exelon Generation Company, LLC),

Preliminary Request for Additional Information Regarding the Braidwood and Byron Requests for Relief Regarding Repair of Reactor Vessel Head Penetration J-Groove Welds, dated January 6, 2016

17. Letter (RS-16-045) from D. M. Gullott (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds," dated February 11, 2016(ML16043A148)

18. Letter (RS-16-057) from D. M. Guflott (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "Supplement to Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds," dated March 15, 2016(ML16075A291)

19. Letter (RS-16-067) from D. M. Guflott (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "Supplement to Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds (RS-16-045)," dated March 22, 2016(ML16082A435)

20. Letter (RS-16-078) from D. M. Gullatt (Exelon Generation Company, LLC) to U.S.

Nuclear Regulatory Commission, "Clarification to Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds" dated April 4, 2016(ML16095A291)

21. Letter from Justin C. Poole (U.S. Nuclear Regulatory Commission) to Bryan C.

Hanson (Exelon Generation Company, LLC), "Byron Station, Units 1 and 2 and Braidwood Station, Units 1 and 2 - Relief from the Requirements of the ASME Code (CAC Nos. MF6715, MF67156, MF6717, and MF6718)," dated April 27, 2016 (ML16109A337)

/SI Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 15 of 33) 10.0 LIST OF FIGURES:

FIGURE A-1: CROM AND RVLIS NOZZLE MACHINING FIGURE A-2: CROM AND RVLIS NOZZLE WELD FIGURE A-3: CROM AND RVLIS NOZZLE EXAMINATION FIGURE A-4: CROM AND RVLIS NOZZLE UT 0° AND 45° L-WAVE BEAM COVERAGE LOOKING CLOCKWISE AND COUNTER-CLOCKWISE FIGURE A-5: CROM AND RVLIS NOZZLE UT 45° L-WAVE BEAM COVERAGE LOOKING DOWN FIGURE A-6: CROM AND RVLIS NOZZLE UT 45° L-WAVE BEAM COVERAGE LOOKING UP FIGURE A-7: CROM AND RVLIS NOZZLE UT 70° L-WAVE BEAM COVERAGE LOOKING DOWN FIGURE A-8: CROM AND RVLIS NOZZLE UT 70° L-WAVE BEAM COVERAGE LOOKING UP FIGURE A-9: CROM AND RVLIS NOZZLE PSI AND ISi WELD AND NOZZLE BASE METAL SURFACE EXAMINATION AREA (A-B-C-D)

FIGURE A-10: CETC NOZZLE MACHINING FIGURE A-11: CETC NOZZLE WELD FIGURE A-12: CETC NOZZLE EXAMINATION FIGURE A-13: CETC NOZZLE UT 0° AND 45°L BEAM COVERAGE LOOKING CLOCKWISE AND COUNTER-CLOCKWISE FIGURE A-14: CETC NOZZLE 45°L UT BEAM COVERAGE LOOKING DOWN FIGURE A-15: CETC NOZZLE 45°L UT BEAM COVERAGE LOOKING UP FIGURE A-16: CETC NOZZLE 70°L UT BEAM COVERAGE LOOKING DOWN FIGURE A-17: CETC NOZZLE 70°L UT BEAM COVERAGE LOOKING UP FIGURE A-18: CETC NOZZLE PSI AND ISi UT EXAMINATION

ISi Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 16 of 33)

I ii I I I I I U_ __ Jj Figure A-1: CRDM and RVLIS Nozzle Machining

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 17 of 33)

TRIPLE PONT

\. /

\ I

\. I

\ I

'v Figure A-2: CRDM and RVLIS Nozzle Weld

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 18 of 33)

~><" is 1.5" for all nozzles.::: 30° and 1" for all nozzles ;. 30° relative to the head surfaoe Post - Machining PT 1-m-n-o-p-q Post - Weld PT m-n-s-p-q-r Post - Weld UT (Weld) a-b-c-d-e-h-a Post - Weld UT (Nozzle e-f-g-h-e Material)

Figure A-3: CRDM and RVLIS Nozzle Examination

IS/ Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 19 of 33)

~

I I

ozzl

~

~

Head I .._

Figure A-4: CRDM and RVLIS Nozzle UT 0° and 45° L-wave Beam Coverage Looking Clockwise and Counter-clockwise

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ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 20 of 33) ozzle H e ad Figure A-5: CRDM and RVLIS Nozzle UT 45° L-wave Beam Coverage Looking Down

ISi Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 21 of 33) o:zzl.e H ea Figure A-6: CRDM and RVLIS Nozzle UT 45° L-wave Beam Coverage Looking Up

/S/ Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 22 of 33)

Nozzle H ea d Figure A-7: CRDM and RVLIS Nozzle UT 70° L-wave Beam Coverage Looking Down

ISi Program Plan Units 1 & 2, Fourth JnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 23 of 33)

Nozzle Rea Figure A-8: CRDM and RVLIS Nozzle UT 70° L-wave Beam Coverage Looking Up

ISi Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 24 of 33)

"a" is 1.5" for all nozzles~ 30° and 1" for all nozzles> 30° relative to the head surface Figure A-9: CRDM and RVLIS Nozzle PSI and ISi Weld and Nozzle Base Metal Surface Examination Area (A-B-C-D)

ISi Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 25 of 33)

I ii I I I I I U_ __ Jj Figure A-10: CETC Nozzle Machining

ISi Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 26 of 33)

UPPER TRIPLE POINT LOWER TRIPLE POINT NOZZLE TO

/ GUIOE WEl D REPLACEMENT GUIDE FUNNEL F igure A-11: CETC Nozzle Weld

IS/ Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 27 of 33)

~

Post - Machining PT k-1"0-p Post - Weld PT ~n-o-p Post - Weld UT a-b-c-d-e-f-g-f-a F igure A-12: CETC Nozzle Examination

ISi Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 28 of 33)

Figure A-13: CETC Nozzle UT 0° and 45°L Beam Coverage Looking Clockwise and Counter-clockwise

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 29 of 33)

H Figure A-14: CETC Nozzle 45°L UT Beam Coverage Looking Down

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 30 of 33)

CKo.zzl.e 451 B6!1!11 CO't'allge Lool:in_g Up Figure A-15: CETC Nozzle 45°L UT Beam Coverage Looking Up

ISi Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 31 of 33)

TCKozzle Head

'iOLB!!!llllCo~

Looldlt_g Da\<11 Figure A-16: CETC Nozzle 70°L UT Beam Coverage Looking Down

ISi Program Plan Units 1 & 2, Fourth Interval 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 32 of 33)

TCKozzle OL BE!!l!ll Coverage LoolingUp Figure A-17: CETC Nozzle 70°L UT Beam Coverage Looking Up

ISi Program Plan Units 1 & 2, Fourth lnteNal 10 CFR 50.55a RELIEF REQUEST Byron Station 14R-11 Revision 0 (Page 33 of 33)

Figure A-18: CETC Nozzle PSI and ISI UT Exa mination

ATTACHMENT 2 10 CFR 50.55a Relief Request Number Byron Station 14R-11 Request for Relief Alternative Requirements for the Repair of Reactor Vessel Head Penetrations in Accordance with 10 CFR 50.55a(z)(1)

(Shown with track changes and included for information only)

ISi Program Plan Units 1 ami& 2, :+hiffJFourth lnteNal 10 CFR 50.55a RELIEF REQUEST 8raidwood Station 13R 1& and 8yron Station 13R 23Byron Station 14R-11 Revision 0 (Page 1 of 34)

Request for Relief Alternative Requirements for the Repair of Reactor Vessel Head Penetrations In Accordance with 10 CFR 50.55a(z)(1) 1.0 ASME CODE COMPONENTS AFFECTED :

Component Numbers:Braidwood and Byron Station , Units 1 and 2, Reactor Vessels 1RC01 R (Unit 1) and 2RC01 R (Un it 2)

Description:

Alternative Requirements for the Repair of Reactor Vessel Head Penetrations (VHPs) with Nozzles Having Pressure-Retaining Partial-Penetration J-groove Welds Code Class : Class 1 Examination Category: ASME Code Case N-729-1 Code Item: 84.20 Identification: Byron Units 1 and 2, VHP Numbers 1 through 78 , (P-1 through P-78) - Except VHPs with Previous Repairs Previous repa irs : Unit 2, P-6 and P-68 and Unit 1, P-31 , P-43, P-64 and P-76 Braidwood Units 1 and 2 , VHP Numbers 1 through 78 , (P 1 through P 78) Except VHPs with Previous Repairs Previous repairs: Unit 1, P 69 Reference Drawing: Closure Head Assembly: Byron I Braidwood ( 185282E)

Size: 4 Inch Nominal Outside Diameter Material Inconel Alloy 600 (SB-167) 2.0 APPLICABLE CODE EDITION AND ADDENDA:

Interval lnservice Inspection (ISi) and Repair/Replacement Programs : American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI ,

r n2007 Edition throughwith the r n2008 Addenda (Reference 1) .. Examinations of the VHPs are performed in accordance with 10CFR50.55a(g)(6)(ii)(D) , which specifies the use of Code Case N-729-1 , with conditions .

Code of Construction [Reactor Pressure Vessel (RPV)]: ASME Section Ill , 1971 Edition through Summer 1973 Addenda .

!SI Program Plan Units 1 aflfl& 2, +hifEIFourth lnteNal 10 CFR 50.55a RELIEF REQUEST 8raid*Nood Station 13R 1i and 8yron Station 13R 28Byron Station 14R-11 Revision 0 (Page 2 of 34) 3.0 APPLICABLE CODE REQUIREMENT:

The applicable requirements of the following Construction Codes for the removal or mitigation of defects from which relief is requested are as follows :

ASME Code.Section XI, 2001XI. 2007 Edition. including with 2008 Addenda through

~

• IWB-3420 states:

Each detected flaw or group of flaws shall be characterized by the rules of IWA-3300 to establish the dimensions of the flaws. These dimensions shall be used in conjunction with the acceptance standards of IWB-3500.

• IWB-3132.3 states:

A component whose volumetric or surface examination detects flaws that exceed the acceptance standards of Table IWB-3410-1 is acceptable for continued service without a repair/replacement activity if an analytical evaluation , as described in IWB-3600, meets the acceptance criteria of IWB-3600. The area containing the flaw shall be subsequently reexamined in accordance with IWB-2420(b) and (c).

ASME Code. Section Ill. 2001 Edition. including Addenda through 2003

• NB-5245, Butt-Welded Nozzles or Branch Connections , specifies progressive surface examination of partial penetration welds.

• NB-5331 (b) states:

Indications characterized as cracks, lack of fusion , or incomplete penetration are unacceptable regardless of length.

Code Case N-638-4, Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique , provides requirements for automatic or machine gas tungsten arc welding (GTAW) of Class 1 components without the use of preheat or post weld heat treatment.

• Paragraph 1(g) states:

Peening may be used, except on the initial and final layers.

The applicable requirements of the following Construction Codes for the removal or mitigation of defects from which relief is not specifically requested are as follows:

ASME Code.Section XI. -2()():1.2007 Edition , including with 2008 Addenda through

~

• IWA-3300 specifies requirements for characterization of flaws detected by inservice examination .

• IWA-4221 (b) states:

An item to be used for repair/replacement activities shall meet the Construction Code specified in accordance with (1 ), (2) or (3) below.

ISi Program Plan Units 1 aRfi& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1S and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 3 of 34)

• IWA-4221 (c) states in part:

As an alternative to (b) above, the item may meet all or portions of the requirements of different Editions and Addenda of the Construction Code, or Section Ill ...

provided the requirements of IWA-4222 through IWA-4226, as applicable , are met

• IWA-4224.1 , Identical material Procured to a Later Edition or Addenda of the Construction Code , Section Ill or Material Specification .

(a) Materials, including welding materials may meet the requirements of later dates ...

(b) Differences in the specified material tensile stress ...

• IWA-4400 provides welding , brazing , metal removal , fabrication , and installation requirements related to repair/replacement activities.

• IWA-4411 states:

Welding , brazing , fabrication , and installation shall be performed in accordance with the Owner's Requirements and , except as modified below, in accordance with the Construction Code of the item.

• IWA-4411 (a) states in part:

Later editions and addenda of the Construction Code, or a later different Construction Code , either in its entirety or portions thereof, and Code Cases may be used , provided the substitution is as listed in IWA-4221 (c) . Filler metal requ irements shall be reconciled , as required , in accordance with IWA-4224.

• IWA-4412 states :

Defect removal shall be accomplished in accordance with the requ irements of IWA-4420.

• IWA-4420(a) states:

Defect removal by mechanical processing shall be in accordance with IWA-4462.

• IWA-4462(b) states :

Where welding is to be performed , the cavity shall be ground smooth and clean with beveled sides and edges rounded to provide suitable accessibility for welding.

• IWA-4611 .1(a) states :

Defects shall be removed in accordance with IWA-4422.1. A defect is considered removed when it has been reduced to an acceptable size.

ASME Code. Section Ill. 1971 Edition. including Addenda through 1973

• Table NB-4622.1-1 requires:

Post Weld Heat Treatment (PWHT) for P3 materials.

IS/ Program Plan Units 1 aoo& 2, +RiffJFourth lnteNal 10 CFR 50.55a RELIEF REQUEST Braid'N99d Stati9n 13R 18 and Byr9n StatiGn 13R 23Byron Station 14R-11 Revision 0 (Page 4 of 34)

Code Case N-729-1 , Alternative Examination Requirements for PWR Reactor Vessel Upper Heads with Nozzles Having Pressure-Retaining Partial-Penetration Welds,Section XI , Division 1, Fig . 2, "Examination Volume for Nozzle Base Metal and Examination Area for Weld and Nozzle Base Metal", is applicable to the VHPs.

Code Case N-749. Alternative Acceptance Criteria for Flaws in Ferritic Steel Components Operating in the Upper Shelf Temperature Range,Section XI, Division 1 4.0 REASON FOR REQUEST:

To ensure timely repair and minimize impact on NRC resource's on an emergent basis, a preemptive submittal of this relief request is being made as a contingency effort to support the required repair for potential indication(s) discovered in upcoming outages.,.

for the Fourth lnservice Inspection Interval. If an indication requiring repair was detected during an ISi Program ultrasonic (UT) examination of the VHPs, the affected VHP(s) will be modified under this request.

Because of the risk of damage to the RVCH material properties or dimensions, it is not feasible to apply the post weld heat treatment (PWHT) requirements of the original Construction Code. As an alternative to the requirements of RVCH Code of Construction, Exelon proposes to perform the modification of the VHP(s) utilizing the Inside Diameter Temper Bead (IDTB) welding method to restore the pressure boundary of the degraded nozzle penetration. The IDTB welding method is performed with a remotely operated weld tool utilizing the machine gas tungsten arc welding (GTAW) process and the ambient temperature temper bead method with 50° F minimum preheat temperature and no PWHT . The modification described below will be performed in accordance with the 2-GG-+2007 Edition , inclblding with 2008 Addenda throblgh 2003 , of ASME Section XI , Code Case N-638-4, Code Case N-729-1 , and the alternatives discussed in 5.0.

Basic steps for the modification are:

1) Removal of a lower portion of the existing thermal sleeve assembly at the applicable VHP(s) to provide access for IDTB welding .

2) Roll expansion above the region to be modified to stabilize the nozzle and prevent any movement when the nozzle is separated from the nozzle to RVCH J-groove weld .

3) Machining to remove the lower nozzle (and CETC nozzle guide at CETC nozzle locations) to an elevation above the J-groove weld eliminating the portions of the nozzle which may contain the unacceptable indication(s}. This machining operation also establishes the weld prep area (Refer to ~Figures A-1 and A-10) .

4) Liquid penetrant (PT) examination of the machined area (Refer to Figures A-3 and A-12).

5) Welding the remaining portion of the nozzle, and replacement CETC nozzle extension at the applicable VHP(s) , to the RVCH using primary water stress corrosion cracking (PWSCC) resistant Alloy 52/Alloy 52M/Alloy 52MSS, hereinafter all referred to as Alloy 52 , weld material (Refer to Figures A-2 and A-11).

6) Machining the weld and nozzle to provide a surface suitable for nondestructive

ISi Program Plan Units 1 aRfi& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST 8raic:lwooc:I Station 13R 1i anc:l 8yron Station 13R 28Byron Station 14R-11 Revision 0 (Page 5 of 34) examination (NOE).

7) PT and UT examination of the weld and adjacent region (Refer to ~Figures A-3 and A-12) .

8) Rotary peening on the portion of the remaining nozzle most susceptible to PWSCC to impart compressive residual stress on the nozzle surface.

9) PT examination of the peened area.

10) Welding of a new lower thermal sleeve assembly at the applicable VHP(s) and I or installation of a CETC nozzle guide at the CETC nozzle locations.

Note the figures in this request are provided to assist in clarifying the above description .

The location of the VHP nozzle welds relative to the inner and outer spherical radii of the RVCH, and the existing J-groove weld will vary depending upon the location of the VHP nozzle and as-found dimensions.

Exelon has determined that modification of the VHP(s) utilizing the alternatives specified in this request will provide an acceptable level of quality and safety. Relief is requested in accordance with 10 CFR 50.55a(z)(1).

5.0 PROPOSED ALTERNATIVE AND BASIS FOR USE:

5.1 IDTB Modification Acceptance Examination ASME Section Ill , 2001 Edition, including Addenda through 2003, NB-5245, specifies progressive surface examination of partial penetration welds . The original Construction Code requirement for progressive surface (PT) examination , in lieu of volumetric examination , was because volumetric examination is not practical for the conventional partial penetration weld configurations. Therefore, the following combination of UT and PT examinations are proposed.

For a CROM and RVLIS nozzle repair/modification, the welds are suitable for UT examination. However, the welds are only accessible from the top side, and therefore limited UT coverage of the volume within the lower taper transition is available as discussed herein (Refer to Figures A-4 thru A-8) . For a CETC nozzle repair/modification , the weld is suitable for UT examination and the weld is accessible from both the top and bottom sides (Refer to Figures A-13 thru A-17).

UT volumetric examination of the repaired/modified configuration will be performed as specified in ASME Code Case N-638-4, 4(a)(2) and 4(a)(4) . The acceptance criteria of NB-5330, in ASME Section Ill , 2001 Edition, including Addenda through 2003, apply to all flaws identified within the repaired/modified volume. Regulatory Guide 1.147, Rev.

17, has conditionally approved Code Case N-638-4 with the condition that UT volumetric examinations are performed with personnel and procedures qualified for the repaired volume and qualified by demonstration using representative samples which contain construction type flaws (see 7.1).

The UT transducers and delivery tooling are capable of scanning from cylindrical surfaces with inside diameters of approximately 2.75 in . The scanning is performed using 0° L-wave transducers , 45° L-wave transducers in two opposed axial directions,

ISi Program Plan Units 1 aRfJ& 2, +RiffJFourth lnteNal 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1S and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 6 of 34) and 70° L-wave transducers in two opposed axial directions as well as 45° L-wave transducers in two opposed circumferential directions. Additionally, the low alloy steel extending to Yi in. beneath the weld into the low alloy steel base material (see Figures A-3 and A-12) will be examined using the 0° L-wave transducers searching for evidence of under bead cracking and lack of fusion in the heat affected zone .

The UT equipment is not capable of scanning from the face of the weld taper at CROM and RVLIS nozzle locations. The 45°L and 70°L axial UT examination scans looking down (see Figures A-5 and A-7) will interrogate the taper transition volume on the CROM and RVLIS nozzle welds. Approximately 70% of the CROM and RVLIS nozzle weld surface is expected to be scanned by UT. Approximately 83% of the RVCH ferritic steel heat affected zone is expected to be covered by UT. The actual CROM and RVLIS nozzle volume examined will be calculated after the as-built dimensions of the weld are known and the examination is performed. It is anticipated that greater than 80% of the examination volume will obtain two-directional coverage for the CROM and RVLIS nozzle modified configuration. There is no portion of the CROM or RVLIS nozzle weld volume that does not receive at least single direction UT coverage. The UT coverage of the modified CETC nozzle configuration will exceed the coverage of the CROM and RVLIS nozzle modified configuration since it receives essentially 100% coverage. The UT examination coverage volumes are shown in Figures A-4 through A-8 for CROM and RVLIS nozzle scans and A-13 through A-17 for CETC nozzle scans.

In addition to the UT examinations , a final surface PT examination will be performed on the entire weld as shown in Figure A-3 for the CROM and RVLIS nozzle welds and Figure A-12 for the CETC nozzle welds. PT examination will also be repeated on the remediated surfaces. Further, the volume in question will be examined to the extent practical using the 70°L and 45°L (see Figures A-5, A-7, A-14, and A-16) axial UT examination scans (looking down). There is no portion of the repair that does not receive surface liquid penetrant examination and at least single-direction UT coverage of the volume. The final examination of the new weld and immediate surrounding region will be sufficient to verify that defects have not been induced in the ferritic low alloy steel RVCH base material, due to the welding , to the extent practical.

The combination of performing PT and UT examinations depicted in Figures A-3 and A-12 during the IDTB repair provides assurance of structural integrity. Thus, EGC requests relief from the progressive surface examination requirements specified in NB-5245.

5.2 Triple Point Anomaly ASME Section Ill , 2001 Edition, including Addenda through 2003, NB-5331 (b) states:

Indications characterized as cracks, lack of fusion, or incomplete penetration are unacceptable regardless of length .

An artifact of ambient temperature temper bead welding is an anomaly in the weld at the triple point. The triple point is the point in the repair weld where the low alloy steel RVCH base material, the Alloy 600 nozzle, and the Alloy 52 weld intersect. The location of the triple point for the CROM and RVLIS nozzle is shown in Figure A-2 and the upper and lower triple points for the CETC nozzle are shown in Figure A-11 .

/SI Program Plan Units 1 aRfl& 2, +hiff:JFourth Interval 10 CFR 50.55a RELIEF REQUEST 8raidwood Station 13R 1& and 8yron Station 13R 23Byron Station 14R-11 Revision 0 (Page 7 of 34)

This anomaly consists of an irregularly shaped very small void. Mock-up testing has verified that the anomalies are common and do not exceed 0.1O in. in length and are assumed to exist, for purposes of analysis , around the entire bore circumference at the triple point elevation.

A fracture mechanics analysis [-t-09] has been performed for the design configuration to provide justification, in accordance with Section XI, for operating with the postulated triple point anomaly. The anomaly is modeled as a 0.1O in. deep crack-like defect, initiating at the triple point location, considering the most susceptible material for propagation. Postulated flaws could be oriented within the anomaly such that there are two possible flaw propagation paths, as discussed below.

Path 1: Flaw propagation is across the nozzle wall thickness from the outside surface to the inside surface of the nozzle.

This is also the shortest path through the new Alloy 52 weld material. By using a fatigue crack growth rate twice that of the rate of Alloy 600 material, it is ensured that another potential path through the heat affected zone between the new weld and the Alloy 600 nozzle material is also bounded.

For completeness, two types of flaws are postulated at the outside surface of the nozzle new IDTB weld . A 360-degree continuous circumferential flaw, lying in a horizontal plane , is considered to be a conservative representation of crack-like defects that may exist in the weld triple point anomaly. Th is flaw is subjected to axial stresses in the nozzle. An axially oriented semi-circular outside surface flaw is also considered since it would lie in a plane normal to the higher circumferential stresses. Both of these flaws would propagate toward the inside surface of the nozzle when subjected to high cyclic stresses in the nozzle penetration repair.

Path 2: Flaw propagation extends down the outside surface of the repair weld between the weld and the RVCH .

A cylindrically oriented flaw is postulated to lie along this interface, subjected to radial stresses with respect to the nozzle. This flaw may propagate through either the new Alloy 52 weld material or the ferritic low alloy steel RVCH base material.

The results of the analyses demonstrate that the 0.1O in. weld anomaly is acceptable for a 40-year design life of the nozzle modification considering the applicable transients and cycles. Sufficient design margins are demonstrated for all flaw propagation paths considered in the analysis. Flaw acceptance is based on criteria for limit load (IWB-3644). Fatigue crack growth is conducted along each flaw propagation paths for the CROM , RVLIS and CETC nozzles. For the postulated axial and circumferential flaws in the Alloy 52 repair weld , the acceptance criteria of IWB-3642 which permits the use of the analytical procedures described in ASME Section XI , Appendix C. For the CROM ,

RVLIS , and CETC nozzle welds, net section collapse analysis is performed for the postulated circumferential flaw. Cross-sectional bending at the postulated flaw locations is insignificant due to the nozzle being encased in the vessel head. The limit load failure is driven by applied membrane stresses and evaluated . The allowable bending stress is

IS/ Program Plan Units 1 ami& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST 8raid*.-Jood Station 13R 18 and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 8 of 34) shown to be more than the applied bending stress . Also, the minimum limit load margins for postulated axial and cylindrical flaws are less than the required safety factor of 2.7, as specified in IWB-3644. For the cylindrical flaws , it is shown that the applied shear stress at the remaining ligament is less than the allowable shear stress per NB-3227 .2.

These evaluations are prepared in accordance with ASME Section XI and demonstrate for the intended service life of the modification that the fatigue crack growth is acceptable and the crack-like indications remain stable. This satisfies the ASME Section XI criteria but does not include considerations of stress corrosion cracking such as PWSCC . Since the postulated crack-like defects at the top of the CROM nozzle weld(s) ,

RVLIS nozzle weld(s) and CETC nozzle weld(s) due to the weld anomaly are not exposed to the primary coolant and the air environment is benign for the materials at the triple point, the crack growth rates from PWSCC are not applicable.

EGC rsquestrequests relief from the acceptance criteria specified in NB-5331 (b) to permit anomalies, as described herein, at the triple point region to remain in service.

5.3 Flaw Characterization and Successive Examinations - RVCH Original J-Groove Weld The assumptions of IWB-3600 are that cracks are fully characterized in order to compare the calculated parameters to the acceptable parameters addressed in IWB-3500. There are no qualified UT examination techniques for examining the original nozzle-to-RVCH J-groove welds . Therefore, since it is impractical to characterize the flaw geometry that may exist therein, it is conservatively assumed the "as-left" condition of the remaining J-groove weld includes flaws extending through the entire Alloy 82/Alloy 182 J-groove weld and buttering . It is further postulated that the dominant hoop stresses in the J-groove weld would create a situation where the preferential direction for cracking would be radial. A radial crack in the Alloy 82/Alloy 182 weld would propagate by PWSCC , through the weld and buttering , to the interface with the low alloy steel RVCH material. Any growth of the postulated "as-left" flaw into the low alloy steel would be by fatigue crack growth under cyclic loading conditions.

The J-groove flaws have been evaluated using worst-case postulated flaw sizes.

Fatigue crack growth for cyclic loading conditions using operational stresses from pressure and thermal loads and crack growth rates from Article A-4300 of Section XI for ferritic material in a primary water environment will be calculated . The results of this evaluation show that, based on a combination of linear elastic fracture mechanics (LEFM) analysis and elastic-plastic fracture mechanics (EPFM) analysis [-++1O] of a postulated remaining flaw in the original Alloy 82/Alloy 182 J- groove weld and buttering for the modified RVCH nozzle is acceptable for the remaining life of the Unit plus a 20 year life extension following an IDTB weld repair.

LEFM and EPFM analyses (441O] were used to demonstrate the remaining service life plus life extension for the remaining worst-case "as-left" flaw in the J-groove weld .

Although the postulated flaw did not satisfy ASME Code Section XI IWB-3612 for all transient loading conditions, LEFM analysis :

• Dstermineddetermined that the uphill side of the VHP penetration is the worst case position for the postulated flaw,

• calculated the final flaw size by fatigue crack growth, and

ISi Program Plan Units 1 aRfi& 2, +hiftJFourth Interval 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1& and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 9 of 34)

• identified the controlling service conditions for evaluation by EPFM analysis.

Crack stress intensity factors for initial "as-left" flaws are first determined using 3-dimensional finite element analysis and applying both residual and operating stresses for each of the applicable transients . Crack size is incremented based on the fatigue crack growth rate equations given in A-4300 of ASME Section XI , as modified by 10CFR50.55a . For the VHP nozzle welds the maximum flaw growth into the RVCH low alloy steel is calculated on the uphill side and on the downhill side and the remaining service life determined . The crack stress intensity factor, including pressure, thermal and residual stress effects , for the final maximum flaw size using the acceptance criteria of IWB-3612 indicated insufficient available fracture toughness to provide the specified margins under all conditions, thus, the appropriate failure mechanism (ductile tearing) was determined below.

Based on a determination that ductile tearing is the failure mechanism for the final flaw under the conditions being evaluated , EPFM analysis is utilized to evaluate the final flaw sizes for all propagation paths. EPFM analysis is performed using a J-integral/tearing modulus (J-T) diagram to evaluate flaw stability under ductile tearing . Additionally, the crack driving force (applied J-integral) is checked against the J-R curve at a crack extension of 0.1O in. (J0 .1). The safety factors that are applied to the primary and secondary stresses in the EPFM analysis are tabulated below:

Safety Factors*

Operating Condition Evaluation Method Primary Secondary Normal/Upset J/T based flaw stability 2.14 1.0 Normal/Upset J0.1 limited flaw extension 1.5 1.0 Emergency/Faulted J/T based flaw stability 1.2 1.0 Emergency/Faulted J0.1 limited flaw extension 1.25 1.0

• EPFM safety factors from Code Case N-749 as modified by the NRC (see attachment in ML14330A510).

The potential for debris from a cracking J-groove partial penetration weld was considered. Radial cracks were postulated to occur in the weld due to the dominance of hoop stresses at this location. This possibility of occurrence of transverse cracks that could intersect the radial cracks is considered remote . There are no forces that would drive a transverse crack. The radial cracks would relieve the potential transverse crack driving forces . The conclusion is that there are no known service conditions that could drive radial cracks and transverse cracks to intersect to produce a loose part.

Flaws are postulated to exist in the remaining portion of the J-groove weld and shown in the evaluation to be acceptable for 33 years of remaining operation (based on a 60 year plant licensed life).

Successive examinations required by IWB-3132.3 will not be performed because analytical evaluation of the worst-case postulated flaw is performed to demonstrate acceptability. A reasonable assurance of the RVCH structural integrity is maintained without the successive examinations .

ISi Program Plan Units 1 ami& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1& and 8yron Station 13R 23Byron Station 14R-11 Revision 0 (Page 10 of 34)

EGC requests relief from flaw characterization specified in IWB-3420 and subsequent examination requirements specified in IWB-2420(b) and IW8-2420(c).

5.4 Rotary Peening Rotary peening is performed on the final layer to provide further assurance of the modified configuration being resistant to PWSCC (4-211 ]. However, peening on the final layer of a temper bead weld is prohibited by ASME Code Case N-638-4, 1(g) . This prohibition is referring to the high cold-work peening that is traditionally used for configuration distortion control during welding , as was interpreted by ASME Xl-1-13-19 for Code Case N-606-1 [4-a14]. This is not considered applicable to the rotary peening process, which is highly controlled , uniform, and only influences a shallow surface layer (approximately 20 mils at the base metal i.e., bounding depth). The uniform compressive stress layer created by the rotary peening process does not inhibit subsequent NOE. Furthermore, this residual compressive stress layer has been shown to greatly reduce PWSCC initiation .

ASME Code Section Ill, Appendix W , W-2140, clearly describes the beneficial nature of compressive stresses for the mitigation of stress corrosion cracking (SCC) susceptibility.

It states that shot peening , as a form of stress improvement, can be used to place the inside diameter of piping in a compressive residual stress state to resist sec. Extensive laboratory testing performed as part of MRP-61 indicates that shot peening successfully inhibits PWSCC initiation. With rotary peening , the shot is captured in a flap and regularly spaced such that it uniformly imparts compressive stresses on metal surfaces.

However, the additional benefits of rotary peening regarding increased PWSCC resistance will not influence the inspection frequency for the modified nozzles as depicted in Code Case N-729-1 .

EGC requests relief from Code Case N-638-4, 1(g) .

5.5 Preservice Inspection (PSI) and lnservice Inspection (ISi) of VHPs Repaired as shown in Figures A-9 and A-18 Examination PSI/ISi Parts Requirement I Examination Acceptance Extent I Examined Figure Method Standard Frequency All nozzles, each CROM I RVLIS Fig. A-9 Surface N-729-1, -3130 refueling outage All nozzles, each CETC Fig.A-18 Volumetric N-729-1 , -3130 refueling outage Code Case (CC) N-729-1 provides requirements for the inspection of VHPs with nozzles having partial penetration welds . CC N-729-1 Table 1, Item 84 .20, permits either volumetric or surface examination . Item 84.20 examination requirements are specified in Figure 2 of CC N-729-1 . Since either volumetric or surface examination is acceptable ,

surface examination will be used for PSI/ISi for repaired CROM and RVLIS nozzles as shown in Figure A-9 due to limited tooling access and volumetric examination will be used for PSI/ISi for repaired CETC nozzles as shown in Figure A-18 (see 7.2).

ISi Program Plan Units 1 ami& 2, ::r:hifflFourth Interval 10 CFR 50.55a RELIEF REQUEST Braid*Nood Station 13R 1& and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 11 of 34)

The repair/modification proposed by this relief request removes much of the examination area depicted in figure 2 of CC N-729-1 at several locations. Thus, Figure A-9 of this relief request is used to establish the examination area of a repaired CROM or RVLIS nozzle for the preservice inspection following repair and for future inservice inspections.

Similarly, Figure A-18 of this relief request is used to establish the examination area of a repaired CETC nozzle for the preservice inspection following repair and for future inservice inspections. The established examination areas are equivalent to that required by Figure 2 in CC N-729-1 ; as it examines the nozzle weld and the same area above the CROM nozzle weld, RVLIS nozzle weld , CETC nozzle weld and the CETC nozzle base material below the weld as would be required by Figure 2 in the Code Case.

Therefore, preservice inspection following repair and future inservice inspections will comply with Code Case N-729-1 as modified by 10 CFR 50.55a(g)(6)(ii)(D) and as depicted in Figures A-9 and A-18 .

5.6 General Corrosion Impact on Exposed Low Alloy Steel The IDTB nozzle modification leaves a small portion of low alloy steel in the RVCH exposed to primary coolant. An evaluation (~ 12] was performed for the potential corrosion concerns at the RVCH low alloy steel wetted surface . Galvanic corrosion ,

hydrogen embrittlement, sec, and crevice corrosion are not expected to be a concern for the exposed low alloy steel base metal. General corrosion of the exposed low alloy steel base metal will occur in the area between the IOTB weld and the original J-groove weld . The general corrosion rate is conservatively estimated to be 0.0036 in./year. The corrosion of the exposed base metal has negligible impact on the RVCH and is acceptable for 40 years from the time the modification is performed .

5. 7 Conclusions Implementation of an IOTB repair to the VHP(s) will produce an effective repair that will restore and maintain the pressure boundary integrity of the VHPs. Similar modifications have been performed successfully and have been in service for several years without any known degradation (e.g ., Shearon Harris, Palisades). This alternative provides improved structural integrity and reduced likelihood of leakage for the primary system .

Accordingly, the use of the alternative provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1 ).

6.0 DURATION OF PROPOSED ALTERNATIVES The analyses of the modified configurations described herein and others for the modified configuration that will be implemented under 10 CFR 50.59 support the remaining life of the original 40 year plant design life plus License renewal life (20 years) of a new 60 year plant design life [4413]. The analysis results are based upon expected repair parameters which may vary during implementation . The design lifetime is sensitive to the vertical length of the Alloy 52 weld ligament and the actual limiting ligament length may vary depending upon the as-found and "as-left" conditions. The design life will be re-evaluated if necessary using as-built data and incorporated into the modification, future NOE schedules, and asset management plans. All repaired RVCH penetration nozzles will be examined in accordance with ASME Code Case N-729-1 as conditioned by 10CFR50.55a(g)(6)(ii)(D) . The periodic examinations will provide reasonable

ISi Program Plan Units 1 aRfi& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1& and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 12 of 34) assurance of the structural integrity of RVCH nozzles prior to exceeding the design life of the repair.

The JJ Ef PY life of the repair is based on the as-left J-Groove flaw evaluation . A combination of linear elastic and elastic-plastic fracture mechanics, show the postulated flaws to be acceptable for a-33 year plantyears of remaining operation Hfe-.utilizing the appropriate safety factors and the lower bound J-R curve from Reg . Guide 1.161 [44}.

1OJ. The results of the weld anomaly flaw evaluation demonstrated that a 0.1O" weld anomaly is acceptable for 40 years of plant life (after a repair) [..W9J. The estimated minimum time for a PWSCC flaw to propagate through 75% of the original wall thickness is over 100 EFPY utilizing rotary peening surface remediation. The overall acceptable life of the repair design is based on the most limiting life predicted amongst the weld anomaly analysis [..W9J, the as-left J-groove analysis [+-i 1OJ and the PWSCC evaluation

[~ 11 J of the original Alloy 600 nozzle, which is JJ Ef PYacceptable for the remaining life of a 60 year plant license.

The provisions of this relief request are applicable for the remainder of the ThirdFourth lnservice Inspection Interval for Byron Station Units 1 and 2, currently scheduled to end on July 15, 2016. The pro*.iisions of this relief request are applicable for the remainder of the Third lnservice Inspection Interval for Braid*Nood Station Units 1 and 2, currently scheduled to end on J1,1ly 2~ . 2013 and October 16, 2013, respectively.2025. The modification installed in accordance with the provisions of this relief shall remain in place for the design life of the modification , until another alternative is approved by the NRC ,

or until the RVCH is replaced.

7.0 ADDITIONAL INFORMATION 7.1 VHP Weld Qualification Mockup UT Acceptance AREVA, in support of many similar modifications, has performed many qualifications using mockups since VHP modifications at Oconee Nuclear Station in 2001 . During these evolutions , the site crew performs training on mockups for each of their respective specialties , i.e., machinists train on machining mockups, welders train on welding mockups, and NOE personnel train on NOE mockups.

UT is required by Code Case N-638-4. NRC Reg . Guide 1.147, Rev. 17 imposes a condition for this code case that requires the examination procedure and examination personnel be qualified by demonstration on representative samples which contain construction type flaws . To satisfy this requirement a mockup containing reflectors to simulate construction type flaws applicable to this weld process has been used. A NiCrFe alloy calibration block is used and contains a series of electrical-discharge machining (EDM) notches at nominal depths of 10%, 25% , 50% , and 75% deep from both inside diameter and outside diameter surfaces in both the axial and circumferential orientation . The block also contains 1/4T, 1/2T, and 3/4T deep end holes and side drilled holes that are used for calibration .

The examination procedure has also demonstrated the ability to detect a linear weld fabrication triple point anomaly extending 0.10 in. into the weld . The examination procedure was used to collect automated data for the demonstration . An IDTB weld NOE mockup was fabricated to replicate the expected configuration . It contains a series

ISi Program Plan Units 1 ami& 2, +hiffJFourth lnteNal 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1S and Byron Station 13R 28Byron Station 14R-11 Revision 0 (Page 13 of 34) of EDM notches at the triple point to simulate the triple point anomaly at various depths into the nozzle wall and cracking at the IDTB weld to low alloy steel interface. It also contains flat bottom holes drilled from the mockup outside diameter so that the hole is normal to the surface to simulate under bead cracking , lack of bond , and lack of fusion .

This is the same mockup used for the procedure qualification for the Davis Besse and Shearon Harris VHP nozzle modifications listed in Section 8.0.

7.2 CETC Nozzle Weld Qualification Mockup UT PSI/ISi The UT examination of the modified configuration has been qualified by demonstration as required by 10CFR50.55a(g)(6)(ii)(D)(4) on a similar mockup configuration that represents the nozzle modification .

8.0 PRECEDENTS

1. Davis-Besse Nuclear Power Station - Relief Request RR-A34, April 1, 2010 ,

ADAMS Accession Number ML100960276

2. Shearon Harris Nuclear Power Plant, Unit 1 - Relief Request 13R-09, October 2, 2012 , ADAMS Accession Number ML12270A258

3. Shearon Harris Nuclear Power Plant, Unit 1 - Relief Request 13R-11 , September 13, 2013, ADAMS Accession Number ML13238A154

4. Shearon Harris Nuclear Power Plant, Unit 1 - Relief Request 13R-13, November 22 , 2013, ADAMS Accession Number ML13329A354

5. Shearon Harris Nuclear Power Plant, Unit 1 - Relief Request 13R-15, Apri l 29, 2015, ADAMS Accession Number ML15120A406

9.0 REFERENCES

1. ASME Code Case N-638-4 Similar and Dissimilar Metal Welding Using Ambient Temperature Machine GTAW Temper Bead Technique ,Section XI , Division 1.

2. NRC Regulatory Guide 1. 147, Revision 17, lnservice Inspection Code Case Acceptability, ASME Section XI , Division 1

3. ASME Code Case N-729-1 Alternative Examination Requirements for PWR Reactor Vessel Upper Heads With Nozzles Having Pressure-Retaining Partial-Penetration Welds ,Section XI , Division 1

4. Materials Reliability Program : An Assessment of the Control Rod Drive Mechanism (CROM) Alloy 600 Reactor Vessel Head Penetration PWSCC Remedial Techniques (MRP-61) , EPRI , Palo Alto, CA: 2003. 1008901 .

5. &:---ASME Code Case N-749 Alternative Acceptance Criteria for Flaws in Ferritic Steel Components Operating in the Upper Shelf Temperature Range ,Section XI ,

Division 1

6. +.:--Byron Station Unit 1 - Relief Request 13R-19, February 1, 2012 , ADAMS Accession Number ML112990783

IS/ Program Plan Units 1 aRfi& 2, +f::liffiFourth lnteNal 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1 &and Byron Station 13R 28Byron Station 14R-11 Revision 0 (Page 14 of 34)

7. g.,.....__Byron Station Unit 2 - Relief Request 13R-14, May 23, 2007, ADAMS Accession Number ML071290011

8. 9-:---Byron Station Unit 2 (13R-20) and Braidwood Station (13R-09). March 29, 2012 , ADAMS Accession Number ML120790647

9. w,.._AREVA Calculation BYR15 032 I BRVV 15 0050 M, "IDTB #32-9237284-002, "!.'. Byron/Braidwood RVCH Nozzle IDTB Repair Weld Anomaly Fracture Mechanics Stress Analysis (32 9237284 000)'""' (Proprietary)

10. +-1-:--AREVA Calculation BYR15 034 / BRVV 15 0052 M, "IDTB #32-9236713-00 ~ . :'."Byron and Braidwood RVCH Repair Fracture Mechanics Stress Analysis (Nozzle As-Left J-Groove Weld) (32 9236713 OOO)"Analysis"!'.

(Proprietary) 11 . 4-2-:--AREVA Calculation BYR15 037 / BRW 15 0054 M, "IDTB RVCH Repair

1. 51-9233902-002 , :'."PWSCC Evaluation (51 9233902 OOO)"for Contingency RVCH Nozzle Repairs at Byron Unit 1 and 2 and Braidwood Units 1 and 2!'."

(Proprietary)

12. ~AREVA Calculation BYR15 036 I BRW 15 0053 M, "IDTB RVCH Repair

1. 51-9234023-002, "!.'.Corrosion Evaluation (51 9234023 OOO)"of Byron Units 1 and 2 and Braidwood Units 1 and 2 IDTB Weld Repairs!'." (Proprietary)

13. 4:---AREVA Calculation BYR15 038 I BRVV 15 0055 M, "IDTB RVCH Repair

1. 51-9240805-004, :'."Byron Units 1 & 2, and Braidwood Units 1 & 2 IOTB Reactor Vessel Head Penetration Nozzle Weld Repair-Life Assessment Evaluation (51 9240805 OOO)"Summary"!.'. (Proprietary)

14. .:t&.-ASME Boiler and Pressure Vessel Code,Section XI , Interpretation Xl-1 19, File No. 13-56, Code Case N-606-1 , June 21, 2013

15. 10.0 Letter (RS-15-236) from D. M. Gullatt (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission , "Requests for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds ," dated September 11 , 2015 (ML15259A049)

16. Email from J. Wiebe (NRC) to J. Krejcie (Exelon Generation Company, LLC) ,

Preliminary Request for Additional Information Regarding the Braidwood and Byron Requests for Relief Regarding Repair of Reactor Vessel Head Penetration J-Groove Welds , dated January 6, 2016

17. Letter (RS-16-045) from D. M. Gullatt (Exelon Generation Company, LLC) to U. S.

Nuclear Regulatory Commission , "Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds," dated February 11 , 2016 (ML16043A148)

18. Letter (RS-16-057) from D. M. Gullatt (Exelon Generation Company, LLC) to U. S.

Nuclear Regulatory Commission , "Supplement to Response to Requests for

ISi Program Plan Units 1 ami& 2, +hifEIFourth lnteNaf 10 CFR 50.55a RELIEF REQUEST 8raidwood Station 13R 1& and 8yron Station 13R 28Byron Station 14R-11 Revision 0 (Page 15 of 34)

Add itional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds ," dated March 15, 2016 (ML16075A291)

19. Letter (RS-16-067) from D. M. Gullatt (Exelon Generation Company, LLC) to U. S.

Nuclear Regulatory Commission , "Supplement to Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds (RS-16-045) ," dated March 22 , 2016 (ML16082A435)

20. Letter (RS-16-078) from D. M. Gullatt (Exelon Generation Company, LLC) to U. S.

Nuclear Regulatory Commission, "Clarification to Response to Requests for Additional Information for Relief for Alternate Requirements for Repair of Reactor Vessel Head Penetrations with Nozzles Having Pressure-Retaining Partial-Penetration J-Groove Welds" dated April 4, 2016 (ML16095A291) 21 . Letter from Justin C. Poole (U.S . Nuclear Regulatory Commission) to Bryan C.

Hanson (Exelon Generation Company, LLC) , "Byron Station, Units 1 and 2 and Braidwood Station , Units 1 and 2 - Relief from the Requirements of the ASME Code (CAC Nos. MF6715, MF67156, MF6717, and MF6718) ," dated April 27 , 2016 (ML16109A337)

ISi Program Plan Units 1 &Rfl& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 18 and 8yron Station 13R 23Byron Station 14R-11 Revision 0 (Page 16 of 34) 10.0 LIST OF FIGURES:

FIGURE A-1: CROM AND RVLIS NOZZLE MACHINING FIGURE A-2: CROM AND RVLIS NOZZLE WELD FIGURE A-3: CROM AND RVLIS NOZZLE EXAMINATION FIGURE A-4 : CROM AND RVLIS NOZZLE UT 0° AND 45° L-WAVE BEAM COVERAGE LOOKING CLOCKWISE AND COUNTER-CLOCKWISE FIGURE A-5: CROM AND RVLIS NOZZLE UT 45° L-WAVE BEAM COVERAGE LOOKING DOWN FIGURE A-6: CROM AND RVLIS NOZZLE UT 45° L-WAVE BEAM COVERAGE LOOKING UP FIGURE A-7: CROM AND RVLIS NOZZLE UT 70° L-WAVE BEAM COVERAGE LOOKING DOWN FIGURE A-8 : CROM AND RVLIS NOZZLE UT 70° L-WAVE BEAM COVERAGE LOOKING UP FIGURE A-9: CROM AND RVLIS NOZZLE PSI AND ISi WELD AND NOZZLE BASE METAL SURFACE EXAMINATION AREA (A-B-C-0)

FIGURE A-10: CETC NOZZLE MACHINING FIGURE A-1 1: CETC NOZZLE WELD FIGURE A-12 : CETC NOZZLE EXAMINATION FIGURE A-13: CETC NOZZLE UT 0° AND 45°L BEAM COVERAGE LOOKING CLOCKWISE AND COUNTER-CLOCKWISE FIGURE A-14 : CETC NOZZLE 45°L UT BEAM COVERAGE LOOKING DOWN FIGURE A-15: CETC NOZZLE 45°L UT BEAM COVERAGE LOOKING UP FIGURE A-16: CETC NOZZLE 70°L UT BEAM COVERAGE LOOKING DOWN FIGURE A-17 : CETC NOZZLE 70°L UT BEAM COVERAGE LOOKING UP FIGURE A-18 : CETC NOZZLE PSI AND ISi UT EXAMINATION

ISi Program Plan Units 1 aRfi& 2, +RiffJFourth lnteNal 10 CFR 50.55a RELIEF REQUEST Braidwaad Statian 13R 1Ei and Byran Statian 13R 23Byron Station 14R-11 Revision 0 (Page 17 of 34)

I ii I I I I I U_ __ Jj Figure A-1: CRDM and RVLIS Nozzle Machining

ISi Program Plan Units 1 &Rfl& 2, +hifflFourth Interval 10 CFR 50.55a RELIEF REQUEST 8raid-.*.issd Statisn 13R 18 and 8yrsn Statisn 13R 288yron Station 14R-11 Revision 0 (Page 18 of 34)

TRIPLE POINT Figure A-2: CRDM and RVLIS Nozzle Weld

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~><M is 1-5" for all nozzl es~ 30° and 1" for all nozzles :> 30° relative to the head s urfaoe Post - Machining PT 1-m-n-o-p-q Post - Weld PT m-n-s-p-q-r Post - Weld UT (Weld) a-b-c-d-e-h-a Post - Weld UT (Nozzle e-f-g-h-e Material)

F igure A-3: CRDM and RVLIS Nozzle Examination

ISi Program Plan Units 1 aRfi& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1& and 8yron Station 13R 23Byron Station 14R-11 Revision 0 (Page 20 of 34)

._/'!

i ozzle Hea d I

I Figure A-4: CRDM and RVLIS Nozzle UT 0° and 45° L-wave Beam Coverage Looking Clockwise and Counter-clockwise

ISi Program Plan Units 1 aRfi& 2, +RiffJFourth lnteNal 10 CFR 50.55a RELIEF REQUEST 8raid>>._*ood Station 13R 1G and 8yron Station 13R 23Byron Station 14R-11 Revision 0 (Page 21 of 34)

N ozzle Head Figure A-5: CRDM and RVLIS Nozzle UT 45° L-wave Beam Coverage Looking Down

ISi Program Plan Units 1 ami& 2, +hiffJFourth lnteNal 10 CFR 50.55a RELIEF REQUEST 8raid*J.'ood Station 13R 1G and Byron Station 13R 28Byron Station 14R-11 Revision 0 (Page 22 of 34) ozzle H ea Figure A-6: CRDM and RVLIS Nozzle UT 45° L-wave Beam Coverage Looking Up

ISi Program Plan Units 1 aRfi& 2, +RiffJFourth lnteNal 10 CFR 50.55a RELIEF REQUEST Braid*1o1ood Station 13R 1S and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 23 of 34)

Nozzle He-ad Figure A-7: CRDM and RVLIS Nozzle UT 70° L-wave Beam Coverage Looking Down

ISi Program Plan Units 1 aRfi& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST 8raid>>'tfood Station 13R 1& and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 24 of 34)

Nozzle Head Figure A-8: CRDM and RVLIS Nozzle UT 70° L-wave Beam Coverage Looking Up

ISi Program Plan Units 1 ami& 2, :+hifflFourth lnteNal 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1S and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 25 of 34)

"a ~ is 1.5" for all nozzles~ 30° and 1" for a ll nozzles > 30° relative to the head surface Figure A-9: CRDM and RVLIS Nozzle PSI and ISi Weld and Nozzle Base Metal Surface Examination Area (A-B-C-D)

IS/ Program Plan Units 1 aRfi& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST Braid'NOOd Station 13R 1S and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 26 of 34)

I I

., .j ' ,,...___ __

I ii I I I I I U_ __ Jj Figure A-10: CETC Nozzle Machining

IS/ Program Plan Units 1 ami& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1S and 8yron Station 13R 23Byron Station 14R-11 Revision 0 (Page 27 of 34)

UPPER TRIPLE POINT LOWER TRIPLE POINT REPLACEMENT GUIDE FUNNEL Figure A-11: CETC Nozzle Weld

ISi Program Plan Units 1 ami& 2, +hiffJFourth lnteNal 10 CFR 50.55a RELIEF REQUEST 8raic:lwooc:I Station 13R 1S and 8yron Station 13R 23Byron Station 14R-11 Revision 0 (Page 28 of 34)

Post - Machining PT k-1-o*p Post - Weld PT m-n-o-D Post - Weld UT a-b-o-d-e-f-g-j-a Figure A-12: CETC Nozzle Examination

/SI Program Plan Units 1 aoo& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1& and 8yron Station 13R 23Byron Station 14R-11 Revision 0 (Page 29 of 34)

He!!d Figure A-13: CETC Nozzle UT 0° and 45°L Beam Coverage Looking Clockwise and Counter-clockwise

ISi Program Plan Units 1 aoo& 2, +RiffJFourth lnteNa/

10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1& and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 30 of 34)

TCKcme H~

45L Beam Covemge Looking D!lv!n Figure A-14: CETC Nozzle 45°L UT Beam Coverage Looking Down

ISi Program Plan Units 1 aRfl& 2, +hiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST 8raidw99d StatiGn 13R 1S and 8yr9n StatiGn 13R 23Byron Station 14R-11 Revision 0 (Page 31 of 34)

TC:t\cmle 451 B8!1111 Covaage Lool:ing up Figure A-15: CETC Nozzle 45°L UT Beam Coverage Looking Up

ISi Program Plan Units 1 aoo& 2, +hiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST 8raid-.*.iood Station 13R 1S and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 32 of 34)

TCKO'ZiZ!e H'3!1d iOL Beam Covemge Looldn_gDo~n Figure A-16: CETC Nozzle 70°L UT Beam Coverage Looking Down

ISi Program Plan Units 1 am:J& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST 8raid*Nood Station 13R 1& and Byron Station 13R 23Byron Station 14R-11 Revision 0 (Page 33 of 34)

H~

701 Beam Cm~

Lool:iltg l:p Figure A-17: CETC Nozzle 70°L UT Beam Coverage Looking Up

ISi Program Plan Units 1 aRfi& 2, +RiffJFourth Interval 10 CFR 50.55a RELIEF REQUEST Braidwood Station 13R 1& and 8yron Station 13R 23Byron Station 14R-11 Revision 0 (Page 34 of 34) e..f leak

• Figure A-18: CETC Nozzle PSI and ISi UT Examination