PNP 2025-067, Additional Information in Support of Relief Request RR 5-12, Proposed Alternative to ASME Section XI Code for Full Structural Weld Overlays of Primary Coolant System Hot Leg, Cold Leg, and Pressurizer Nozzle Dissimilar Metal Weld
| ML25260A638 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 09/16/2025 |
| From: | Fleming J Holtec Palisades |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| Shared Package | |
| ML25260A636 | List: |
| References | |
| PNP 2025-067 | |
| Download: ML25260A638 (1) | |
Text
PROPRIETARY INFORMATION - WITHHOLD UNDER 10 CFR 2.390 This letter is decontrolled when separated from Attachment 2 27780 Blue Star Highway, Covert, MI 49043 PNP 2025-067 10 CFR 50.55a September 16, 2025 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Palisades Nuclear Plant NRC Docket No. 50-255 Renewed Facility Operating License No. DPR-20
Subject:
Additional Information in Support of Relief Request RR 5-12, Proposed Alternative to ASME Section XI Code for Full Structural Weld Overlays of Primary Coolant System Hot Leg, Cold Leg, and Pressurizer Nozzle Dissimilar Metal Welds Pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a, Codes and standards, Holtec Palisades hereby provides additional information in support of Nuclear Regulatory Commission (NRC) review and approval of the previously submitted Relief Request RR 5-12 for the Palisades Nuclear Plant (PNP) dated August 20, 2025 (ML25232A195). to this letter provides the NRC Questions and the Holtec Palisades Response. provides the requested evaluation which contains information considered proprietary to Framatome. On behalf of Framatome, Holtec Palisades request that the NRC withhold this information in accordance with 10 CFR 2.390. provides the Framatome Affidavit Proprietary Information Notice. contains a non-proprietary version of this evaluation. Upon removal of the proprietary information in Attachment 2, the balance of this submittal is decontrolled.
Holtec is requesting NRC approval by October 3, 2025.
This letter contains no new regulatory commitments and no revisions to existing regulatory commitments.
HOLTEC PALISADES
PNP 2025-067 Page 2 of 2 Please refer any questions regarding this submittal to Frank Sienczak PNP Regulatory Assurance Manager, at (269) 764-2263.
Respectfully, Jean A. Fleming Vice President, Licensing, Regulatory Assurance and PSA Holtec International Attachments: 1. NRC Questions and Holtec Palisades Responses
- 2. Framatome Document No. 51-9392688-000, Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays (Proprietary Information - Withhold Under 10 CFR 2.390)
- 4. Framatome Document No. 51-9392853-000, Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays (Non-Proprietary) cc:
NRC Region III Regional Administrator NRC Senior Resident Inspector - Palisades Nuclear Plant NRC Project Manager - Palisades Nuclear Plant
PNP 2025-067 ATTACHMENT 1 NRC Questions Followed by Holtec Responses
PNP 2025-067 Questions and Responses NRC Question # 1: Would it be possible to provide Framatome Evaluation 51-9384372-000, Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays, on the docket?
Holtec Palisades Response: The requested document number 51-9384372-000 is the Life Assessment Summary for the Reactor Vessel Closure Head (RVCH) project and was listed as Reference 8 in the submittal dated August 20, 2025. In the submittal the document was inadvertently misnumbered. The correct document number for the Alloy 600 Life Assessment Summary is 51-9392688-000. The requested evaluation is included as Attachment 2 and contains information considered proprietary to Framatome. On behalf of Framatome, Holtec Palisades request that the NRC withhold this information in accordance with 10 CFR 2.390; provides the Framatome Affidavit Proprietary Information Notice. Attachment 4 contains a non-proprietary version of this evaluation. Upon removal of the proprietary information in Attachment 2, the balance of this submittal is decontrolled.
NRC Question # 2: The staff has a question about the Code Case N-638-4 conditions specified in RG 1.147, Revision 21, and whether Holtecs welding activities meet the two conditions specified in Table 5 (pages 35 and 36, ML23291A003), which are:
Demonstration for ultrasonic examination of the repaired volume is required using representative samples that contain construction type flaws and, The provisions of Paragraph 3(e)(2) or 3(e)(3) may only be used when it is impractical to use the interpass temperature measurement methods described in Paragraph 3(e)(1) such as in situations where the weldment area is inaccessible (e.g., internal bore welding) or when there are extenuating radiological conditions.
Holtec Palisades Response: Holtec Palisades welding activities meet the two conditions imposed on Code Case N-638-4 in RG 1.147, Revision 21, as discussed below and stated in the highlighted text shown below, taken from PDF page 55 of the submittal.
The ultrasonic examination personnel and procedure that was used were qualified in accordance with ASME Code Section XI, Mandatory Appendix VIII, Supplement 11, as implemented through the EPRI Performance Demonstration Initiative (PDI) Program.
The qualification test specimens that were used contained both construction and in-service type flaws, as required by Mandatory Appendix VIII, Supplement 11, and the proposed modifications discussed in Attachment 5 of the August 20, 2025, submittal.
The interpass temperature was determined by direct measurement for all weld overlays.
The alternative provisions specified in Paragraphs 3(e)(2) and 3(e)(3) of Code Case N-638-4 were not used. Note that these alternative provisions were omitted in the proposed alternative presented in Attachment 3 of the August 20, 2025, submittal.
PNP 2025-067 ASME Code Case N-740-2 Requirement Included in Proposed Alternative?
Justification MANDATORY APPENDIX I, AMBIENT-TEMPERATURE TEMPER BEAD WELDING Yes Ambient temperature temper bead welding will be performed in accordance with Mandatory Appendix I, as specified in Attachment 3 of this Relief Request. The requirements in Mandatory Appendix I were taken from ASME Code Case N-638--4, which was conditionally approved by the NRG in RG 1.147 with conditions related to nondestructive examination (NOE) and to interpass temperature measurement. Holtec will meet the additional requirements specified in RG 1.147.
The NRC previously approved the use of the Mandatory Appendix I requirements for DMW FSWOLs in Precedents 3 and 5 listed in Attachment 1, Section 7.0.
Exceptions to N-740:2 Mandatory Appendix I:
Paragraph 1-2 is updated to incorporate subparagraph 2(b) of ASME Code Case N-638-1 1, which has been unconditionally approved by the NRC.
Paragraph 1-2.1(a) is replaced with paragraph 2.1 (a) of ASME Code Case N-638-1 1, which has been unconditionally approved by the NRC.
NRC Question # 3: The request letter (page 1) indicates that the PNP Primary Coolant System (PCS) Hot Leg, Cold Leg, and Pressurizer Nozzle Dissimilar Metal Welds have experienced primary water stress corrosion cracking (PWSCC). Clarification is needed on whether the postulated crack sizes in the crack growth analysis are bounding for the sizes of the detected cracks.
Holtec Palisades Response: Primary water stress corrosion cracking (PWSCC) is a well-documented phenomenon in the nuclear power industry. Components of Alloy 82/182/600 materials in pressurized water reactors have risk for PWSCC at dissimilar metal (DM) welds.
There is no identification that PWSCC cracking has occurred at PNP in any of the loop nozzles, including the PORV nozzle after repair in 1995.
For Palisades nozzles that received full structural weld overlays (FSWOL), a pre-weld PT examination of the surface covered by the overlay is performed in accordance with Section 1.2(d) of ASME Code Case N-740-2. If a rejectable surface indication is detected, the indications are either removed, reduced in size, or repaired with a local weld repair or a seal weld.
Because no ultrasonic examination is performed prior to application of the overlay, inside-surface-connected planar flaws cannot be directly detected. Therefore, the flaw growth analyses for the repaired nozzles conservatively postulate an initial flaw depth of at least 75% of the original wall thickness, measured from the inside surface, in accordance with ASME Code Case N-740-2 Section 2(a). The analyses consider both:
An inside surface-connected, partial through-wall, full (360°) circumferential flaw in a cylinder, and An inside surface-connected, partial through-wall, semi-elliptical axial flaw with a conservative flaw aspect ratio (flaw length to depth) of 4:1, selected to bound the combined width of the weld plus buttering plus any adjacent SCC susceptible material per requirements of N-740-2 Section 2(a)(2).
PNP 2025-067 Additionally, for cases when PT examination of the outer diameter (OD) surface identified any indication that is sealed, the flaw growth analysis conservatively postulates an initial flaw depth equal to 100% of the original wall thickness for both the circumferential and axial flaws. This means that the analysis does not account for the original material thickness, which is a conservative approach.
PNP 2025-067 ATTACHMENT 2 Framatome Document No. 51-9392688-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays (Proprietary Information)
[Withhold Under 10 CFR 2.390]
PNP 2025-067 ATTACHMENT 3 Framatome Affidavit, Proprietary Information Notice (2 pages follow)
A F F I D A V I T
- 1.
My name is Philip A. Opsal. I am Manager, Product Licensing for Framatome Inc. (formally known as AREVA Inc.), and as such I am authorized to execute this Affidavit.
- 2.
I am familiar with the criteria applied by Framatome to determine whether certain Framatome information is proprietary. I am familiar with the policies established by Framatome to ensure the proper application of these criteria.
- 3.
I am familiar with the Framatome information contained in Framatome Engineering Information Record, Document 51-9392688-000 entitled, Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection,
Pressurizer Surge, and Pressurizer Relief Weld Overlays referred to herein as this Document.
Information contained in this Document has been classified by Framatome as proprietary in accordance with the policies established by Framatome 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 Framatome 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 Framatome to determine whether information should be classified as proprietary:
(a)
The information reveals details of Framatomes 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 Framatome.
(d)
The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for Framatome in product optimization or marketability.
(e)
The information is vital to a competitive advantage held by Framatome, would be helpful to competitors to Framatome, and would likely cause substantial harm to the competitive position of Framatome.
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 Framatomes 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 Framatome only as required and under suitable agreement providing for nondisclosure and limited use of the information.
8.
Framatome 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.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on July 23, 2025.
Philip A. Opsal Manager, Product Licensing, Framatome Inc.
Philip A. Opsal
~Q-~
)hilioAOsal
PNP 2025-067 ATTACHMENT 4 Framatome Document No. 51-9392688-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays (Non-Proprietary)
20004-028 (03/26/2024)
Page 1 of 12 Framatome Inc.
Engineering Information Record Document No.:
51 9392853 -
000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary framatome
20004-028 (03/26/2024)
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 2 Safety Related? YES NO Does this document establish design or technical requirements? YES NO Does this document contain assumptions requiring verification? YES NO Does this document contain Customer Required Format?
YES NO Signature Block Name and Title Signature and Date Role Scope/Comments Stacy Yoder Engineer IV P
All John Neil Engineer IV R
All Craig Wicker Materials Supervisor A
All Role Definitions:
P/R/A designates Preparer (P), Reviewer (R), Approver (A);
LP/LR designates Lead Preparer (LP), Lead Reviewer (LR);
M designates Mentor (M);
PM designates Project Manager (PM)
SL YODER 7/23/2025 CJ NEIL 7/23/2025 CA WICKER 7/23/2025 framatome
20004-028 (03/26/2024)
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 3 Record of Revision Revision No.
Pages/Sections/
Paragraphs Changed Brief Description / Change Authorization 000 All Original issue.
Proprietary information is indicated by bold brackets [ ].
The proprietary version of this document is 51-9392688-000.
The non-proprietary version of this document is 51-9392853-000.
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 4 Table of Contents Page SIGNATURE BLOCK................................................................................................................................ 2 RECORD OF REVISION.......................................................................................................................... 3
1.0 INTRODUCTION
AND PURPOSE............................................................................................... 5 2.0 ASSUMPTIONS............................................................................................................................ 5 2.1 Unverified Assumptions..................................................................................................... 5 2.2 Justified Assumptions........................................................................................................ 5 3.0 RESULTS...................................................................................................................................... 6 3.1 FSWOL Sizing Calculations.............................................................................................. 6 3.2 ASME B&PV Code Section III Analyses........................................................................... 7 3.3 Weld Residual Stress Analyses........................................................................................ 8 3.4 ASME B&PV Code Section XI Appendix C Crack Growth Analyses................................ 8 3.5 Piping System Impact Analysis......................................................................................... 9
4.0 CONCLUSION
............................................................................................................................10
5.0 REFERENCES
............................................................................................................................11 framatome
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 5
1.0 INTRODUCTION
AND PURPOSE Primary water stress corrosion cracking (PWSCC) is a well-documented phenomenon in the nuclear power industry. Components fabricated from Alloy 82/182/600 materials in pressurized water reactors have risk for PWSCC at dissimilar metal (DM) welds. As a result, Framatome Inc. has been contracted by Holtec Palisades LLC (Owner of Palisades Nuclear Plant (PNP)) to mitigate DM welds using full structural weld overlays (FSWOLs) at multiple nozzle locations on the hot legs (HLs), cold legs (CLs), and pressurizer (PZR). Namely, these include the HL surge and shutdown cooling nozzles, the CL safety injection nozzles, and the PZR surge and pilot-operated relief valve (PORV) nozzles [1].
The purpose of this document is to summarize the results of the analyses performed to qualify the design life of the FSWOL modifications to the DM welds of the HL, CL, and PZR nozzles. These analyses include FSWOL sizing calculations, American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV)
Code Section III analyses, weld residual stress (WRS) analyses, ASME B&PV Code Section XI Appendix C crack growth evaluations, and a piping system impact analysis.
Evaluations and modifications summarized herein are performed in accordance with Reference [1].
2.0 ASSUMPTIONS 2.1 Unverified Assumptions This document does not contain any unverified assumptions.
2.2 Justified Assumptions This document does not contain any justified assumptions.
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 6 3.0 RESULTS This section summarizes the results of the analyses performed to qualify the life of the FSWOL modifications performed on the HL, CL, and PZR nozzle DM welds, which minimally spans the remainder of the 60-year licensed operational life of the plant plus an additional 20-year operational life cycle extension [1].
3.1 FSWOL Sizing Calculations Sizing calculations were performed for each nozzle DM weld configuration to specify the minimum FSWOL length and thickness required in accordance with ASME B&PV Code Section XI, Division 1, Appendix C, 2007 Edition including addenda through 2008 [2]. The FSWOL sizing calculations performed in these documents do not include any allowance for fatigue crack growth, weld material dilution, or final machining. Crack growth evaluations are performed in separate documents to add allowance to the FSWOL thickness for crack growth. The FSWOL sizing does not consider any non-destructive examination inspection requirements. The minimum thickness and length of each nozzle FSWOL are listed below:
1.
HL Surge Nozzle (Reference [3]):
a.
Minimum thickness of [
] over the surge nozzle and surge line pipe.
b.
Minimum length of [
] thickness beyond the projected flaw on the flaw end and [
] on the unflawed end, with an end transition slope not exceeding 30° per Code Case N-740-2 (2)(b)(2) (Reference [4]).
2.
HL Shutdown Cooling Nozzle (Reference [5]):
a.
Minimum thickness of [
] side of the safe end, and a minimum thickness of [
] side of the safe end.
b.
Minimum length of [
] at the pipe and extending [
] at the nozzle with an end transition slope not exceeding 30°, per Reference [4].
3.
CL Safety Injection Nozzles (Reference [6]):
a.
Minimum thickness of [
] side of the safe end and a minimum thickness of [
] of the safe end.
b.
Minimum length extending beyond the projected flaw at least [
]
side and [
] side, with an end transition slope not exceeding 30°,
per Reference [4].
4.
PZR Surge Nozzle (Reference [7]):
a.
Minimum thickness of [
] the pipe.
b.
Minimum length of [
] on the flaw end and [
] on the unflawed end with an end transition slope not exceeding 30°, per Reference [4].
5.
PZR PORV Nozzle (Reference [8]):
a.
Minimum thickness of [
] the pipe.
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 7 b.
Minimum length of [
] on the flaw end and [
] on the unflawed end, with an end transition slope not exceeding 30°, per Reference [4]
3.2 ASME B&PV Code Section III Analyses Engineering calculations were performed for each FSWOL nozzle modification. The purpose of these calculations is to evaluate the FSWOL designs and the associated overlaid components/regions with respect to the primary stress, primary plus secondary stress, and cumulative fatigue usage criteria as prescribed by ASME B&PV Code Section III, Subsection NB and Section III Appendices, 2019 Edition [9] for the new Nickel-based alloy FSWOL material. Stress limits for the existing materials are taken from the 1965 Edition ASME B&PV Code Section III Appendices with Addenda through Winter 1966 [10]. For the HL surge nozzle, CL safety injection nozzle, and PZR PORV nozzle, additional stress limits for the existing materials that did not yet appear in the 1965 Edition with Addenda through Winter 1966 were therefore sourced from additional addenda through Winter 1967 [11].
The ASME B&PV Code stress analyses involve two basic sets of criteria: 1) assure that failure does not occur due to application of the design loads, and 2) assure that failure does not occur due to repetitive service loading.
The primary stress intensity criteria imposed by ASME B&PV Code Section III are the basic requirements in calculating the weld overlay size, wherein the assumption is made that a 360° circumferential flaw has grown completely through the original weld. Loading conditions in each service level were considered in the weld overlay sizing calculations (see Section 3.1). The nozzle to pipe regions are reinforced by the FSWOL by adding materials to the nozzle outside region. This relieves the primary stress burden resulting from internal pressure and external loads. Therefore, with the exception of specific locations of the CL safety injection nozzle FSWOL modification (detailed later), the primary stress intensity requirements for the nozzles, welds, safe ends, and pipes have been satisfied for all service levels without the need for further evaluation. Related criteria include the minimum required pressure thickness and reinforcement area addressed in the original nozzle designs. Adding weld overlay will increase the nozzle wall thickness; therefore, these requirements are satisfied.
The analysis of the HL surge nozzle FSWOL in Reference [12] demonstrates that all applicable primary plus secondary stress and cumulative fatigue usage criteria prescribed by ASME Code Section III, Subsection NB (Reference [9]) are satisfied. For the minimum thickness of the Alloy 690 FSWOL configuration, the maximum cumulative usage factor (CUF) calculated for 80 years of operation is [
] located at the inside diameter (ID) of the nozzle cladding below the toe of the Alloy 690 FSWOL. For the maximum thickness of the Alloy 690 FSWOL configuration, the maximum CUF calculated for 80 years is [
] of the Alloy 690 FSWOL on the surge line pipe.
The analysis of the HL shutdown cooling nozzle FSWOLs in Reference [13] demonstrates that all applicable primary plus secondary stress and cumulative fatigue usage criteria prescribed by Reference [9] are satisfied. The maximum CUF calculated for the Nickel-based alloy FSWOL for 60 years of operation is [
] This is conservative because the FSWOL will only be subjected to 30 years of operation (10 years remaining in the current 60-year operating license plus a potential 20-year life extension). The overall maximum fatigue usage calculated for the original nozzle geometry within the region impacted by the implementation of the FSWOL has been found in the cladding material to be [
] for 80 years of operation.
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 8 The analysis of the CL safety injection nozzle FSWOL in Reference [14] demonstrates that all applicable primary plus secondary stress and cumulative fatigue usage criteria prescribed by Reference [9] are satisfied. The maximum CUF calculated for the structure is [
] for the minimum FSWOL configuration and [
]
for the maximum FSWOL configuration (both cases occurring within the cladding) for the proposed 80-year design life. A limit analysis was performed prior to performing the regular ASME B&PV Code Section III qualification to confirm that the updated design (which is performed to repair excavations of penetrant testing indications found on the stainless steel body of the check valves) meets the plastic analysis requirements. It was demonstrated that the design loads were below k
- CL, where k is specified in Table XIII-3200-1 of Reference [9]
and CL is the collapse load. Therefore, the primary stress requirements are not required to be met at specific locations.
The analysis of the PZR surge nozzle FSWOL in Reference [15] demonstrates that all applicable primary plus secondary stress and cumulative fatigue usage criteria prescribed by Reference [9] are satisfied. The maximum CUF calculated in the Nickel-based alloy FSWOL for 30 years of operation is [
] The overall maximum fatigue usage calculated for the original nozzle geometry within the region impacted by the implementation of the FSWOL has been found in the surge line pipe base metal material (outboard of the pipe-to-safe end weld) to be [
] for 80 years of operation.
The analysis of the PZR PORV nozzle FSWOL in Reference [16] demonstrates that all applicable primary plus secondary stress and cumulative fatigue usage criteria prescribed by Reference [9] are satisfied. The maximum CUF calculated in the Nickel-based alloy FSWOL is [
] for 60 years of operation. This is conservative because the FSWOL will only be subjected to 30 years of operation (10 remaining in the current 60-year license plus a potential 20-year life extension). The overall maximum CUF calculated for the original nozzle geometry, found in the nozzle to head junction, is [
] for 80 years of operation.
3.3 Weld Residual Stress Analyses The WRS induced by the FSWOL modifications are calculated and documented for each nozzle: Reference [17]
for the HL surge nozzle, Reference [18] for the HL shutdown cooling nozzles, Reference [19] for the CL safety injection nozzle, Reference [20] for the PZR surge nozzle, and Reference [21] for the PZR PORV nozzles.
The purpose of the WRS analyses is to perform finite element analysis of the nozzle Alloy 82/182 welds mitigated by the FSWOL process. The analyses include simulation of the existing nozzle butter welds, the existing Alloy 82/182 weld attaching the nozzles to the safe ends, the existing DM welds attaching the safe ends to the associated piping (except for the analysis of the PZR PORV nozzle), and the proposed FSWOL mitigations.
Except for the analysis performed for the PZR PORV nozzle, where the original weld was partially removed and replaced in a previous repair, the analyses also include simulation of a conservatively estimated 50% through-wall 360° full circumferential ID repair at the Alloy 82/182 weld attaching the nozzles to the safe ends.
The result of the analyses is state of stress after welding and operating (heat up/cool down) cycles as predicted by ANSYS finite element analysis. These stress results are used as an input to the ASME B&PV Code Section XI Appendix C crack growth analyses. The WRS analysis documents do not make any conclusions regarding the life of the modifications.
3.4 ASME B&PV Code Section XI Appendix C Crack Growth Analyses The purpose of the Appendix C crack growth analyses is to evaluate the fatigue and PWSCC growth of postulated, inside surface-connected, 360° circumferential and semi-elliptical axial flaws in the nozzles modified by the FSWOL. The evaluations consider sustained and transient stresses associated with transient cycles, weld residual stresses, and sustained stresses due to pipe external loads, pressure, and thermal stratification loads (where applicable). The analyses can be used to establish the acceptable period of operation between inspections framatome
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 9 based on the predicted crack growth calculated by the guidelines of Non-Mandatory Appendix C of ASME Code Section XI [2]. The actual period of plant operation between inspections for the components below will be based on the results summarized herein in consultation with ASME Code Case N-770-7, as modified by 10 CFR 50.55a, and any limitations imposed by the NRC.
The results of each evaluation demonstrate that the acceptance criteria for Reference [2] are met for the periods of operation listed below:
1.
HL Surge Nozzle FSWOL (Reference [22]):
a.
4.3 years of plant operation following the installation of the FSWOL 2.
HL Shutdown Cooling Nozzle FSWOL (Reference [23]):
a.
29 years of plant operation following the installation of the FSWOL (i.e., through the year 2054) 3.
CL Safety Injection Nozzle FSWOL (Reference [24]):
a.
29 years of plant operation following the installation of the FSWOL (i.e., through the year 2054) 4.
PZR Surge Nozzle FSWOL (Reference [25]):
a.
8.2 years of plant operation following the installation of the FSWOL 5.
PZR PORV Nozzle FSWOL (Reference [26]):
a.
29 years of plant operation following the installation of the FSWOL (i.e., through the year 2054).
3.5 Piping System Impact Analysis The piping system impact analysis [27] evaluates permanent impacts to the PNP reactor coolant system (RCS) piping and the attached RCS branch piping by performing Alloy 600 mitigation on the RCS branch connection nozzles and the RCS PZR by the FSWOL process.
The performance of the FSWOL process has three permanent impacts on the RCS run piping and the RCS branch piping that are evaluated:
1.
The structural weld overlay along the defined axial length of the Alloy 600 safe end will cause axial weld shrinkage that will result in a permanent axial displacement of the branch piping. The axial weld shrinkage displacement of the RCS branch piping must be evaluated.
a.
The axial weld shrinkage for the HL surge nozzle, HL shutdown cooling nozzle, CL safety injection nozzles, and PZR surge nozzle is specified as a bounding value of [
]
then verified through the process traveler. The axial weld shrinkage for the PZR PORV nozzle is specified as a bounding value of [
] then verified through the process traveler.
b.
For the HL surge nozzle, HL shutdown cooling nozzle, CL safety injection nozzles, and PZR surge nozzle FSWOL configurations, it is demonstrated that a [
] axial weld shrinkage displacement of the nozzle safe end weld overlay will have no significant impact on the piping, spring supports of the piping lines, or the rigid supports (where applicable). For the PZR PORV nozzle FSWOL configuration, it is demonstrated that a [
] axial weld shrinkage displacement of the nozzle safe end weld overlay will have no significant impact on the piping or supports of the PZR PORV discharge line.
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 10 2.
The structural weld overlay deposit of new weld metal will add additional weight to the RCS branch connection nozzle. This additional weight added to the RCS piping must be evaluated for impact on deadweight and seismic loads applied to the RCS piping and the branch piping.
a.
For the HL surge nozzle, HL shutdown cooling nozzle, and CL safety injection nozzle FSWOL configurations, it is demonstrated that the small weight increase will have no significant impact on the deadweight and seismic loads applied to the associated RCS piping and PZR piping and associated supports. It is demonstrated, with the very large weight of the RCS PZR, the additional weight of the FSWOL for the PZR surge and PZR PORV nozzle modifications will have no impact on the RCS PZR.
3.
The structural weld overlay will increase the thickness of the nozzle safe end, which will increase the stiffness of the branch connection nozzle. The increase in branch connection nozzle stiffness must be evaluated for impact on seismic loads applied to the RCS piping and the branch piping.
a.
For all nozzle configurations, it is demonstrated that the small increase in stiffness of the associated pipe runs will have no significant impact on the deadweight, seismic, or thermal loads for the associated RCS piping and PZR piping.
Therefore, installation of the FSWOL on the RCS HL surge line nozzle (Loop 1), RCS HL shutdown cooling nozzle (Loop 2), RCS CL safety injection nozzles (Loops 1A, 1B, 2A, and 2B), RCS PZR surge line nozzle, and the RCS PZR PORV nozzle will have no significant impact on the RCS piping, the RCS branch lines, any pipe supports on the RCS branch lines, or on the RCS Pressurizer.
4.0 CONCLUSION
Based on the analyses and evaluations summarized above, the FSWOL modifications to the DM welds of the HL, CL, and PZR nozzles meet the requirements of ASME B&PV Section III, Division 1 and ASME B&PV Section XI, Division 1, Appendix C. The results of the FSWOL sizing calculations and fatigue life evaluations demonstrate that the design of the FSWOL modifications to the DM welds of the HL surge and shutdown cooling nozzles, CL safety injection nozzle, and PZR surge and PORV nozzles are acceptable for continued operation until the end of the 60-year licensed life plus a 20-year life extension (2054) for a total of 80 years of operation.
The piping system impact analysis demonstrates that the design of the FSWOL modifications to the DM welds of the HL surge and shutdown cooling nozzles, CL safety injection nozzle, and PZR surge and PORV nozzles will have no significant impact on the RCS piping, the RCS branch lines, any pipe supports on the RCS branch lines, or on the RCS Pressurizer.
The ASME B&PV Code,Section XI, Appendix C crack growth evaluations demonstrate that the acceptance criteria of ASME B&PV Code,Section XI, Division 1, Appendix C, 2007 Edition including Addenda through 2008 for the HL shutdown cooling nozzle, CL safety injection nozzle, and PZR PORV nozzle FSWOL designs are met for 29 years of plant operation following the FSWOL installations. The ASME B&PV Code,Section XI, Appendix C crack growth evaluations demonstrate that the acceptance criteria of ASME B&PV Code,Section XI, Division 1, Appendix C, 2007 Edition including Addenda through 2008 for the HL surge nozzle and the PZR surge nozzle are met for 4.3 years and 8.2 years of plant operation, respectively, following the FSWOL installations. The actual period of plant operation between inspections for these components will be based on the results summarized herein in consultation with ASME Code Case N-770-7, as modified by 10 CFR 50.55a, and any limitations imposed by the NRC.
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 11
5.0 REFERENCES
- 1.
Framatome Inc. Document 08-9373560-002, Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays, March 2025.
- 2.
ASME Boiler and Pressure Vessel Code,Section XI, Division 1, Appendix C, 2007 Edition including Addenda through 2008.
- 3.
Framatome Inc. Document 32-9373588-000, Palisades Hot Leg Surge Nozzle FSWOL Calculation, November 2024.
- 4.
ASME Boiler and Pressure Vessel Code, Case N-740-2, Full Structural Dissimilar Metal Weld Overlay for Repair or Mitigation of Class 1, 2, and 3 Items,Section XI, Division 1.
- 5.
Framatome Inc. Document 32-9378287-000, Palisades Shutdown Cooling Nozzle Weld Overlay Sizing Calculation, November 2024.
- 6.
Framatome Inc. Document 32-9378428-000, Palisades Safety Injection Nozzle Weld Overlay Sizing Calculation, November 2024.
- 7.
Framatome Inc. Document 32-9373621-000, Palisades Pressurizer Surge Nozzle Full Structural Weld Overlay (FSWOL) Sizing Calculation, November 2024.
- 8.
Framatome Inc. Document 32-9376351-000, Palisades 4 Power Operated Release Valves (PORV) Full Structural Weld Overlay (FSWOL) Sizing Calculation, February 2025.
- 9.
ASME Boiler and Pressure Vessel Code,Section III, Subsection NB and Appendices, 2019 Edition.
- 10.
ASME Boiler and Pressure Vessel Code,Section III, Appendices, 1965 Edition with Addenda through Winter 1966.
- 11.
ASME Boiler and Pressure Vessel Code,Section III, Appendices, 1965 Edition with Addenda through Winter 1967.
- 12.
Framatome Inc. Document 32-9383549-000, Palisades Hot Leg Surge Nozzle Full Structural Weld Overlay Section III Analysis, April 2025.
- 13.
Framatome Inc. Document 32-9381279-000, ASME Section III Analysis-Palisades Shutdown Cooling Nozzle SWOL, May 2025.
- 14.
Framatome Inc. Document 32-9380067-000, Palisades ASME Section III Analysis for Safety Injection Weld Overlay, May 2025.
- 15.
Framatome Inc. Document 32-9385420-000, ASME Section III Analysis - Palisades Pressurizer Surge Nozzle SWOL, May 2025.
- 16.
Framatome Inc. Document 32-9384467-000, ASME Section III Analysis - Palisades PORV Nozzle FSWOL, April 2025.
- 17.
Framatome Inc. Document 32-9377011-000, Palisades Hot Leg Surge Nozzle FSWOL Weld Residual Stress Analysis, November 2024.
- 18.
Framatome Inc. Document 32-9377012-000, Palisades Hot Leg Shutdown Cooling Nozzle FSWOL Weld Residual Stress Analysis, December 2024.
Document No.: 51-9392853-000 Life Assessment Summary for Palisades Hot Leg Surge, Hot Leg Shutdown Cooling, Cold Leg Safety Injection, Pressurizer Surge, and Pressurizer Relief Weld Overlays - Non-Proprietary Page 12
- 19.
Framatome Inc. Document 32-9377013-001, Palisades Cold Leg Safety Injection Nozzle FSWOL Weld Residual Stress Analysis, April 2025.
- 20.
Framatome Inc. Document 32-9377014-000, Palisades Pressurizer Surge Nozzle FSWOL Weld Residual Stress Analysis, January 2025.
- 21.
Framatome Inc. Document 32-9377015-000, Palisades Pressurizer PORV Nozzle FSWOL Weld Residual Stress Analysis, November 2024.
- 22.
Framatome Inc. Document 32-9390082-000, Palisades Hot Leg Surge Nozzle FSWOL Crack Growth Appendix C Analysis, June 2025.
- 23.
Framatome Inc. Document 32-9388381-000, Palisades Hot Leg Shutdown Cooling Nozzle FSWOL Crack Growth Appendix C Analysis, May 2025.
- 24.
Framatome Inc. Document 32-9390804-000, Palisades Cold Leg Safety Injection Nozzle FSWOL Crack Growth Appendix C Analysis, June 2025.
- 25.
Framatome Inc. Document 32-9390540-000, Palisades Pressurizer Surge Nozzle FSWOL Crack Growth Appendix C Analysis, May 2025.
- 26.
Framatome Inc. Document 32-9389899-000, Palisades Pressurizer PORV FSWOL Crack Growth Appendix C Analysis, May 2025.
- 27.
Framatome Inc. Document 32-9379550-000, Palisades - Evaluation of the Impact On Piping of the Alloy 600 Mitigation Weld Repairs for the Reactor Coolant System Hot Leg and Cold Leg Piping, November 2024.