ML24197A241
| ML24197A241 | |
| Person / Time | |
|---|---|
| Site: | Electric Power Research Institute |
| Issue date: | 07/24/2024 |
| From: | Lois James Licensing Processes Branch |
| To: | Gerond George Licensing Processes Branch |
| References | |
| EPID L-2022-PPM-0000 | |
| Download: ML24197A241 (1) | |
Text
MEMORANDUM TO: Gerond A. George, Chief Licensing Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM:
Lois M. James, Senior Project Manager /RA/
Licensing Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF JULY 16, 2024, MEETING TO UPDATE AND DISCUSS ELECTRIC POWER RESEARCH INSTITUTE'S ACTIVITIES ON PROBABILISTIC FRACTURE MECHANICS AND NONDESTRUCTIVE EXAMINATION OF CAST AUSTENITIC STAINLESS STEEL (EPID L-2022-PPM-0000)
On July 16, 2024, the U.S. Nuclear Commission (NRC) staff met with Electric Power Research Institute (EPRI) representatives to receive an update from and discuss EPRIs activities on probabilistic fracture mechanics (PFM) and nondestructive examination (NDE) of cast austenitic stainless steel (CASS). The meeting summary is Enclosure 1 and the list of attendees is.
If you have any questions or comments, please contact me via e-mail at Lois.James@nrc.gov.
Docket No. 99902021
Enclosures:
1.
Meeting Summary 2.
List of Attendees CONTACT: Lois M. James, NRR/DORL/LLPB 301-415-3306 July 24, 2024 Signed by James, Lois on 07/24/24
U.S. Nuclear Regulatory Commission Public Meeting Summary
Title:
Update and Discussion on Electric Power Research Institutes (EPRI's) Work on Probabilistic Fracture Mechanics (PFM) and Nondestructive Examination (NDE) of Cast Austenitic Stainless Steel (CASS)
Date of Meeting:
July 16, 2024, 9:00 - 11:00 am Location:
Hybrid Type of Meeting: This was an Observation Meeting in which attendees had an opportunity to observe the U.S. Nuclear Regulatory Commission (NRC) performing its regulatory function or discussing regulatory issues. Attendees had an opportunity to ask questions of the NRC staff or make comments about the issues discussed following the business portion of the meeting; however, the NRC is not actively soliciting comments toward regulatory decisions at this meeting.
Purpose of the Meeting: To update and discuss EPRI's work on Probabilistic fracture mechanics (PFM) and nondestructive examination (NDE) of CASS General Details: The NRC staff held a public, observational meeting with EPRI to discuss EPRI's work on PFM and NDE of CASS at nuclear power plants. The meeting began at 9:00 am and ended at 11:00 am. There were twenty-seven NRC staff, five EPRI participants, and five industry participants. No members of the public participated in the meeting. The meeting began with introductions of the NRC staff and EPRI participants.
Summary of Meeting: EPRI began by explaining that because of the CASS material microstructure, Ultrasonic Testing (UT) technology applied to CASS components currently do not have the capable of meeting the Performance Demonstration Initiative (PDI) qualification standards that have been developed for other piping materials, particularly with regards to detection of axial flaws and depth-sizing of circumferential flaws.
As described in EPRI Technical Report 3002023893 Materials Reliability Program: Probabilistic Fracture Mechanics Evaluation of PWR [pressurized water reactor] Cast Austenitic Stainless Steel Piping Components (MRP-479), EPRI developed a PFM software code called PIPER-CASS (Piping Integrity Probabilistic Evaluation for Reactors - Cast Austenitic Stainless Steel) to address the challenges in qualification of UT examinations for CASS piping.
EPRI explained that MRP-479 is the technical basis document for currently proposed Code Cases for American Society of Mechanical Engineering (ASME)Section XI, Inservice Inspection of Nuclear Power Plant Component, and will be used to support ASME Section XI Appendix VIII, Performance Demonstration for Ultrasonic Examination Systems, Supplement 9.
EPRI stated that the purpose of this meeting was to discuss details of MRP-479, discuss plans for proposed Code Cases, and update on EPRI NDE research on CASS.
In describing MRP-479, EPRI began by defining the CASS piping components within scope of the report:
Main loop and surge line piping in domestic PWR designs o
Short segment of pipe fittings subject to examination is treated as straight piping, consistent with IWB-3641 approach o
Similar metal welds and CASS at unmitigated dissimilar metal welds are in-scope These piping components containing CASS material is used in:
Westinghouse (WEC) main loop piping components B&W RCP inlets and outlets Combustion Engineering (CE) RCP inlets/outlets and nozzle safe ends AP-1000 RCP discharge nozzle outlet CE plants surge line piping (except no CASS in surge line for CE-80 design)
The components do not include in the scope of this effort include:
Surge line when the plant is operating under flexible power operations (FPO)
Other branch connections Steam generator (SG) to RCP weld in the AP-1000 PWSCC susceptible material EPRI explained that PIPER-CASS applies the same acceptance criteria as MRP-362, Materials Reliability Program: Technical Basis for ASME Section XI Code Case N-838Flaw Tolerance Evaluation of Cast Austenitic Stainless Steel (CASS) Piping Components, Revision 1.
MRP-362, Revision 1, provides the technical basis for Code Case N-838, which is conditionally approved by the US NRC (with conditions unrelated to the PFM acceptance criteria), in Regulatory Guide 1.147, Inservice Inspection Code Case Applicability, ASME Section XI, Division 1, Revision 20 (ADAMS Accession No. ML21181A222).
EPRI explained that the PFM results show that structural integrity is maintained without crediting periodic examination to detect axially oriented flaws. These results apply to main loop piping components under base load and flexible power operations and to surge line piping components under base load operation.
In addition, EPRI explains that the PFM results show structural integrity is maintained by applying the alternative flaw evaluation methodology for circumferential cracks without relying on depth-sizing information.
The NRC made a few comments:
Understanding depth flaw capability would be helpful Sectioning more piping section would support results EPRI then discussed ASME Record 23-2033 which is a Code Case that proposes alternative inspection requirements that do not require examinations to detect axial cracking in CASS piping components at circumferential butt welds in the main loop and surge line. EPRI explained that this proposed code case applies to axial flaws in primary water stress-corrosion cracking (PWSCC) resistant weld material if the ultrasonic beam would need to pass through CASS to examine that volume. Below is the tentative schedule for ASME Record 23-2033.
ASME Code Action Date Address comments on Record 23-2033 and present at various Working Group meetings August 2024 Develop potential letter ballot to be send to various Working Groups Prior to November 2024 Address comments at various Working Group meetings Present Record 23-2033 at various Subgroup meetings November 2024 Develop potential letter ballot for various Subgroups Prior to February 2025 Address Record 23-2033 comments at various Subgroup meetings and present at Standards Committee meeting February 2025 EPRI requests comments from the NRC staff prior to the end of August 2024 to support the ASME code review actions. The NRC staff stated that they can provide comments, but not necessarily prior to the end of August 2024.
EPRI then discussed ASME Record 24-1062 which is a Code Case proposed as an alternative to IWB-3642 for flaw evaluation requirements for circumferentially oriented flaws in CASS piping components (to address flaw-depth-sizing challenge for CASS). Below is the tentative schedule for ASME Record 24-1062.
ASME Code Action Date Address comments on Record 24-1062 and present at various Working Group meetings August 2024 Develop potential letter ballot to be send to various Working Groups Prior to November 2024 Address comments at various Working Group meetings Present Record 24-1062 at various Subgroup meetings November 2024 Develop potential letter ballot for various Subgroups Prior to February 2025 Address Record 24-1062 comments at various Subgroups meetings Present at Standards Committee meeting February 2025 EPRI requests comments from the NRC staff prior to the end of August 2024 to support the ASM code review actions. The NRC staff stated that they can provide comments, but not necessarily prior to the end of August 2024. The staff also asked that when these actions are balloted at various Groups, that sufficient time for replying to the ballot be assigned to ensure staff could thoroughly comment on the Code Cases.
EPRIs last topic was to provide the NRC staff with an update on CASS piping NDE research.
These efforts will aim to help limit the technical challenges that NDE has experienced in examining CASS material and to allow for development of a Supplement 9 to Appendix VIII.
EPRI explained that this research to improve the depth size capabilities is important to the surge line inspection and examination.
Public Participation Themes: No member of the public attended the hybrid meeting.
Action Items/Next Steps: The NRC staff will prepare and issue a meeting summary.
Attachments: Meeting description and agenda - ADAMS Accession No. ML24197A239 EPRI slide presentation - ADAMS Accession Nos.
Presentation 1, EPRI Project Overview - PFM Evaluation of PWR CASS Piping Components - ML24197A233 Presentation 2, Summary of MRP-479 - Technical Basis for Changes to Inspection and Flaw Evaluation of CASS PWR Piping Components -
ML24197A235 Presentation 3, Proposed ASME Section XI Code Cases - Changes to Inspection and Flaw Evaluation of CASS PWR Piping Components -
ML24197A236 Presentation 4, Research Update on CASS Piping NDE - CASS Research Focus Area - ML24197A237 U.S. Nuclear Regulatory Commission Public Meeting - Attendees List July 16, 2024
Title:
Update and Discussion on EPRI's Work on Probabilistic Fracture Mechanics (PFM) and Nondestructive Examination (NDE) of Cast Austenitic Stainless Steel (CASS)
Name U.S. Nuclear Regulatory Commission (NRC) Participants Isaac Anchondo-Lopez NRC Rondal Ballinger NRC Mat Burton NRC Phyllis Clark NRC Jay Collins NRC Stephen Cumblidge NRC Robert Davis NRC Dale Delisle NRC James Delosreyes NRC David Dijamco NRC Carolyn Fairbanks NRC Gerond George NRC Matthew Homiack NRC Lois James NRC Varoujan Kalikian NRC Robert Martin NRC Kevin McCormick NRC Seung Min NRC Matthew Mitchell NRC Carol Moyer NRC Carol Nove NRC Jeff Poehler NRC Pat Purtscher NRC David Rudland NRC Robert Tregoning NRC Dan Widrevitz NRC John Wise NRC Electric Power Research Institute (EPRI) Participants Name Affiliation James Cirilli EPRI Craig Harrington EPRI Douglas Kull EPRI Carl Latioais EPRI DJ Shim EPRI Industry Participants Name Affiliation Jana Bergman CurtisWright Kevin Fuhr Dominion Engineering, Inc. (Dominion)
Troy Meurer Dominion Glenn White Dominion Timothy Polich RoPower Public Participants Name Affiliation No members of the attended
ML24197A241 (EPRI slides are listed in summary)
^via eConcurrence
- via e-mail NRR-106 OFFICE DORL/LLPB/PM DORL/LLPB/LA DNRL/SLA DNRL/NPHP/BC NAME LJames DHarrison DRudland MMitchell DATE 07/19/2024 07/19/2024 07/23/2024 07/22/2024 OFFICE DNRL/NVIB DORL/LLPB/BC DORL/LLPB/PM NAME ABuford GGeorge LJames DATE 07/22/2024 07/24/2024 07/24/2024