ML26048A333
| ML26048A333 | |
| Person / Time | |
|---|---|
| Issue date: | 02/17/2026 |
| From: | Michelle Gonzalez Office of Nuclear Regulatory Research |
| To: | Jonathan Evans Office of Nuclear Regulatory Research |
| References | |
| Download: ML26048A333 (9) | |
Text
February 17, 2026 MEMORANDUM TO:
Jonathan Evans, Chief Probabilistic and Risk Assessment Branch Division of Risk Assessment Office of Nuclear Regulatory Research FROM:
Michelle Gonzalez, Risk and Reliability Analyst /RA/
Probabilistic and Risk Assessment Branch Division of Risk Assessment Office of Nuclear Regulatory Research
SUBJECT:
SUMMARY
OF U.S. NUCLEAR REGULATORY COMMISSION (NRC) PRA REALISM PUBLIC WORKSHOP (SEPTEMBER 30, 2025-JANUARY 7, 2026.
On September 30, 2025, and January 7, 2026, the U.S. Nuclear Regulatory Commission (NRC) held a two-day workshop to discuss PRA realism. The objective of this two-day workshop was to provide a forum for the NRC and the industry to discuss ongoing efforts to improve PRA Realism. Topics discussed included PRA modeling applications, operating experience, external hazards, human reliability analysis, regulatory and oversight applications, realism for advanced reactors and public perspectives.
Public workshop material, including meeting agenda and NRC and industry presentation materials are available in ADAMS under the following Accession Number: PRA Realism Workshop (ML25272A195). A list of attendees is included in Enclosure 1. The details of the meeting and discussion points are contained in Enclosure 2.
Please direct any inquiries to Ms. Michelle Gonzalez at 301-415-5661 or by email at michelle.gonzalez@nrc.gov.
Enclosures:
- 1. List of Attendees
- 2. Meeting Details
LIST OF ATTENDEES Michelle Gonzalez NRC Lance Rakovan NRC Jeff Rotton NRC David McClain NRC Lundy Pressley NRC Danielle Bocage NRC Dale Yielding NRC Reinaldo Rodriguez NRC Qin Pan NRC Todd Hilsmeier NRC Alex Garmoe NRC Susan Cooper NRC Jing Xing NRC Matthew Leech NRC Matt Humberstone NRC April Pulvirenti NRC Duane Hardesty NRC Steven Trotter ORNL Daisuke Fukuhara NRA Heather Watkins NRC Michael Howard Sunwoo Park NRC John Lane NRC Brian Smith NRC Malcolm Patterson NRC Mark Nutt PNNL Ching Ng NRC Huan Li NRC Philip McKenna NRC Yang Peng Latonia Enos-Sylla NRC Michael Kido DOE M Miller Anthony Leshinskie Vermont David Skutt NY Health Sary Alhatib ANL Samuel Olatubosum Entergy Ellen Bryant NY Health Andrea Maioli Westinghouse Adriana Politi Meitner Energy Dan Geary NRC Ben Ratichek NRC Pamela Hintz ODH Ohio Steven Short PNNL Agustin Saavedra Meitner Energy Soraya Atencio Meitner Energy Brad Bishop Marcelo Caputo Meitner Energy Zheng Xiaoyu JAEA Christopher Chaves DOE William Schlichting Enercon Farshid Shahrokhi Framatome Manuel Garcia Roura Meitner Energy Darrell Gardner Kairos Power Max Ross Sargentlundy Bryan Daiber Entergy Jill Monahan PSU Evan Berg Eric Thornsbury EPRI Marshall Buroff Kris Cummings NuScale Dr abhijit sengupta Barry Mingst Sunday Agbo Holtec Casey Smith NRC Eric Miller NRC Sarah Bristol NuScale Ewa Musikova Edwin Lyman UCS David Oheir Health NY Federico Mezio Meitner Energy Nick Melly NRC Fernando Ferrante EPRI Veronica Godinez Carroll Trull EPM inc.
Jenn Tifft Kevan Griffith Costello, Cynthia Health NY Ricardo Davis GVH Jodine Jansen Vehec BWXT Kevin Coyne NRC James Mitchell Entergy Jonathan Li GVH Sarah McMahon Joseph Cunningham NRC Michael Divittorio Dominion Energy Dennis Henneke Jonathan Evans NRC Kaven Liu Dave Gasperson NRC Adam Lee NRC Lindsey Zimmerman Core Power Hongbin Zhang Sergio Sanchez Meitner Jay Robinson NRC Matthew Degonish Vistra Kyle Barnes Holtec Nathan Wahlgren X-Energy Jenn Tift Mostafa Hamza X-Energy Zhiping Li John Beal Juliana Butler Jack A.
X-Energy Mihai Diaconeasa NCSU Deann Raleigh Tenisha Meadows NRC Aaron Letner Paul Amico Ashley Lindeman EPRI Drew Nigh X-Energy Ono Masato NRA Fatma Ylmaz Kerry Gaston Entergy Rishi Garg DOE John Gayler ANS Daniel Lerew Southern Co.
Joy Jiang The Breakthrough Institute Michael Swim NRC Shahin Seyedhosseini PSEG Nuclear Jonathan De Jesus NRC Enrique Melendez Asensio CSN Yan Peng Sarah Ramos Constellation Nuclear Eilish Matthews Ameren Rob Burg EPM Jonathan David Gore TVA Jacob Joshua Johnson TVA Andrew Layne Energy-Northwest Monica Kalal Chlastosz TVA Keith Vincent FPL Christina England DOE Kelli Voelsing NEI Nathan Jordan Entergy Bradley Donal TVA Joel Font Drew Childs NRC Christopher Thornton Amy Fitzgerald Oakridge David Aird NRC Justin Hiller Ameren Zhegang Ma INL Daniel Ju NRC Ethan Graven Jensen Hughes Evan Davidson NRC Thinh Dinh NRC Jennifer Beaton NRC Ben Chen X-Energy James Chang NRC Tom Stephen NRC Trish Gallalee NRC Zhiping Li Gerardo Martinez NRC Charles Moutlon NRC Naeem Iqbal NRC Isaac Mulhern Ameren Mark M Bill Spellane Bob Youngblood Andy Ratchford Jensen Hughes Rawan Mustafa NCSU Shrijan Dhakal Entergy Ben Chen X-Energy Bill Spellane Angela Smith INL Thamirys Cury Entergy Kevin Hsueh NRC Sarah Abramson Rob Whelan Ming Zhu DOE Jim Schneider NuScale Azin Al Kajbaf NRC Cindy Williams Barry Quigley Carman James ORNL Yeon-Ki Chung RPI Edu Payton Morvant Entergy Danielle Page Blair Framatome Hongbin Zhang Min Berg Kaven Liu Shane Williams Terra Power Sunil Weerakody NRC Ali Azarm Bryan Nevius Dominion Energy B Hitchco Travis Chapman BWXT Charles Adams Wisconsin Gov.
Ricardo Davis GVH Evan Berg Hanley Kaitlin Ryan Som Juliana Butler Adrienne Brown NRC Chris Hunter NRC Reinaldo Rodriguez NRC Victoria Anderson NEI Marty Stuzke NRC Doug True NEI Alan Kuritzky NRC Steven Alferink NRC Gabe Taylor NRC Nick Melly NRC Suzanne Loyd Constellation Mary Presley EPRI Gary Demoss PSEG Joe Kanney Sunwoo Park Jordan Rice Southern Co.
Brad Dolan TVA
MEETING DETAILS PRA REALISM WORKSHOP Purpose The purpose of this two-day workshop was to provide a forum for the NRC and the industry to discuss ongoing efforts to improve PRA Realism.
Meeting Details This workshop was originally scheduled for September 30-October 1, 2025; however, the second day was interrupted by the Federal Government shutdown and subsequently rescheduled for January 7, 2026. All workshop materials, including the agenda and presentations, are available in ADAMS under Accession Number ML25272A195. A summary of the workshop discussions is provided below.
Day 1 The first day of the workshop began with Russell Felts (NRC), Deputy Office Director, Office of Nuclear Regulatory Research, providing opening remarks and welcoming attendees. In his opening remarks, Mr. Felts acknowledged the importance of improving PRA realism in current PRA practices. Doug True, Chief Nuclear Officer and Senior Vice President, Technical &
Regulatory Services, The Nuclear Energy Institute (NEI), also provided NEIs views on the topic of PRA realism.
The meeting proceeded with discussions on several key topics, summarized as follows:
Introduction to PRA Realism This discussion was led by Dr. Kevin Coyne (NRC), who provided an overview of PRA Realism. He explained the concept of realism, its role in enhancing critical NRC activities, and emphasized the importance of continuing efforts to further improve realism in PRA practices.
PRA Modeling Applications This workshop session centered on ongoing initiatives to enhance realism in PRA applications across both the NRC and industry.
The NRC staff highlighted current activities involving SPAR (Michelle Gonzalez),
advancements in Level 3 modeling (Alan Kuritzky), digital I&C (Steve Alferink),
and fire research (Nick Melly).
Ashley Lindeman presented EPRIs efforts to improve fire realism.
Suzane Loyd (BWROG) addressed modeling conservatisms in utility PRAs.
Mary Presley (EPRI) discussed PRA realism in the context of digital I&C.
Operating Experience This session focused on data collection initiatives from both the NRC and the industry.
John Lane (NRC) provided an overview of the NRCs data collection efforts, while Gary Demoss (PSEG) and Matt Degonish (PWROG) discussed the industrys activities in this area.
External Hazards Activities This session focused on various activities related to external hazards.
Joseph Kanney (NRC) discussed ongoing flooding research efforts and provided an overview of the Process for Ongoing Assessment of Natural Hazards Information (POANHI) initiative.
Sunwoo Park (NRC) discussed the importance of seismic PRA realism and some of the related challenges.
Fernando Ferrante (EPRI) provided an overview of EPRIs initiatives concerning external hazards.
Human Reliability Analysis (HRA)
In this session, Jing Xing (NRC) provided an overview of IDHEAS-ECA, including its current status and ongoing activities. James Chang (NRC) discussed the use of simulator data to inform human error probability estimates, while Mary Presley (EPRI) highlighted industry efforts aimed at achieving greater realism in HRA.
Day 2 The second day of the workshop (January 7, 2026) began with Brian Smith (NRC) providing a recap of the discussions from Day 1, followed by in-depth sessions on the following topics:
Regulatory and Oversight Applications This session featured several presentations on key topics:
Gerardo Martinez (NRC) provided an update on the NRC PRA standards activities.
Qin Pan (NRC) discussed the reactor oversight process, emphasizing the role of realism in the significance determination process.
Chris Hunter (NRC) discussed the revised Accident Sequence Precursor Program (ASP) review process and common cause failure modeling. He also provided an overview of the recent RASP Handbook updates.
Adrienne Brown (NRC) addressed PRA realism expectations for licensing activities.
Reinaldo Rodriguez (NRC) discussed PRA configuration control.
Victoria Anderson (NEI) discussed industry regulatory activities, and Fernando Ferrante (EPRI) provided an update on EPRIs defense-in-depth initiatives.
Realism for Advanced Reactors In this session, Marty Stutzke (NRC) discussed approaches to enhancing PRA realism for advanced reactor designs, while Eric Thornsbury (EPRI) provided an overview of EPRIs ongoing initiatives and research efforts in this area.
Public Perspectives During this portion of the meeting, members of the public were invited to share their views on PRA realism. Dr. Edwin Lyman (Union of Concerned Scientists) provided feedback on several topics discussed throughout the workshop. He expressed concern that increasing PRA realism could lead to a reduction in conservatism within PRA models, which may impact safety margins.
Questions and discussion:
Fire research It was noted that while fire events are considered high-risk in PRA models, actual occurrences are rare. This highlights the need to identify and evaluate existing conservatisms.
Victoria Anderson emphasized that licensees may not always be able to incorporate detailed fire scenarios into their models.
Additional input from subject matter experts is needed to determine which conservatisms warrant further study. This will help prioritize efforts on the most significant areas.
The NRC Fire and External Hazards staff proposed holding a follow-up public meeting to explore these issues in greater detail. They also suggested discussing the lack of data related to other external hazards.
Common Cause Failure Chris Hunter expressed that NRC is coming up with a plan soon on common cause failure data updates. He suggested a follow-up meeting to discuss CCF data in the coming months. Industry agreed with this proposition.
PRA models There is a concern over the timing between industry PRA model updates (every 2 refueling cycles). There are not many changes from one update to the next one but the process to update is very resource intensive. EPRI is developing strategies to somehow reduce the scope of these updates.
There was a question related to whether the NRC was planning to develop SPAR models for non LWRs. At this time, the NRC is focusing on LWRs, but will revise as new designs come in.
Advanced Reactors What are the limitations on the use of legacy data for advanced reactors (e.g.,
use French data)? Caution should be exercised when utilizing legacy data.
While such data can serve as a useful starting point, it should primarily be used to inform expert elicitation rather than as a definitive source.
How is the NRC planning to address SPAR models and SDPs for new and advanced reactors? No decisions have been made yet over whether we're going to develop SPAR models for all the advanced reactors, or if the NRC could somehow adapt licensees PRA models.
What metric would be used for offsite consequences for the new reactors that might be transportable? There are various factors to consider, climate, weather patterns, locations, etc., but the NRC has no definite answer on this matter yet.