ML20106F135

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March 25-26, 2020 Public Meeting on Spent Fuel Performance Margins
ML20106F135
Person / Time
Issue date: 04/13/2020
From: Paul Kallan
NRC/NRR/DNRL/NRLB
To: Tara Inverso
NRC/NRR/DRO
Kallan P
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Download: ML20106F135 (11)
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April 13, 2020 MEMORANDUM TO: Tara Inverso, Acting Deputy Director Division of Fuel Management Office of Nuclear Materials Safety and Safeguards FROM: Paul Kallan, Project Manager /RA/

New Reactor Licensing Branch Division of New and Renewed Licenses Office of Nuclear Reactor Regulation

SUBJECT:

SUMMARY

OF THE MARCH 25-26, 2020, CATEGORY 1 PUBLIC WORKSHOP ON SPENT FUEL PERFORMANCE MARGINS On March 25 - 26, 2020, the U.S. Nuclear Regulatory Commission (NRC) held a Category 1 public workshop with the Nuclear Energy Institute (NEI) and other industry representatives to discuss NEIs white paper on Spent Fuel Performance Margins (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19318D971). This workshop built upon discussions held during the January 22, 2020, public workshop (summary available at ADAMS Accession No. ML20028F277) and focused on two technical areas: thermal margins and source terms. The goal of the workshop was to align on the problem statement, requested regulatory products, and next steps for the associated recommendations. Approximately 64 people, including NRC staff, industry and members of the public, participated in the meetings via Skype and bridgeline.

The public workshop notice dated March 9th, 2020, can be found in ADAMS under Accession No. ML20077J441. This meeting notice was also posted on the NRC public website. Enclosed is the meeting agenda (Enclosure 1), list of participants (Enclosure 2), an overview of the meeting (Enclosure 3) and a Table providing a summary of the discussion surrounding the problem statements, requested regulatory products, and next steps (Enclosure 4).

NRCs presentation material is available in ADAMS:

  • Spent Fuel Storage and Transportation Issue Resolution Plan - Recommendation III-3 (Category II): ADAMS Accession No. ML20078J643 NEIs presentation materials are available in ADAMS:
  • Spent Fuel Performance Margins: Source Terms - Presentation March Workshop:

ADAMS Accession No. ML20079J118

  • Proposed Table of Contents (TOC) for Thermal Fuel Performance Topical Report:

ADAMS Accession No. ML20080F893

  • NEI Workshop

Introduction:

ADAMS Accession No. ML20080K251

T. Inverso

  • SFWST Perspectives on Thermal Modeling: ADAMS Accession No. ML20085F142 In terms of next steps, the NRC is planning on conducting future workshops, including on the following topics:

o Dose Rates, Graded Approach, Reviews of Applications that Utilize Phenomena Identification and Ranking Tables, Gross Rupture (~ April 2020) o PIRTs, Remaining Category 3 Items (Summer 2020)

These workshops will be posted to the NRCs public meeting website in advance of each meeting date.

Enclosures:

1. Meeting Agenda
2. List of Attendees
3. Meeting Overview
4. Table CONTACT: Paul Kallan, NRR/DNRL 301-415-2809

ML20106F135 *via e-mail NRR-106 OFFICE DNRL/NRLB/PM NRR/DRO/Special Assistant DNRL/NRLB/PM NAME PKallan* TInverso* PKallan* (signed)

DATE 4/13/20 4/13/20 4/13/20 U.S. NUCLEAR REGULATORY COMMISSION CATEGORY 1 PUBLIC WORKSHOP ON SPENT FUEL PERFORMANCE MARGINS

PUBLIC MEETING AGENDA

March 25TH, 2020 (Day 1)

Time Topic Speaker 9:00 AM Introductions/Opening Remarks NRC/NEI TBD Break (as needed Industry Presentations on Thermal 9:15 AM NEI Margins 12:00 PM Break for Lunch Presentation on Approach for Draft Best 1:00 PM NRC/NEI Practices Guide for Thermal Modelling TBD Break (as needed) 3:30 PM Opportunity for Public Comment All 3:50 PM Closing Remarks NRC/NEI 4:00 PM Meeting Adjourn Enclosure 1

U.S. NUCLEAR REGULATORY COMMISSION CATEGORY 1 PUBLIC WORKSHOP ON SPENT FUEL PERFORMANCE MARGINS

PUBLIC MEETING AGENDA

March 26TH, 2020 Time Topic Speaker 9:00 AM Introductions/Opening Remarks NRC/NEI TBD Break (as needed)

Industry Presentations on Source 9:15 AM NEI Terms 12:00 PM Break for Lunch Industry Presentation on Draft Source 1:00 PM NRC/NEI Term Conservatism Road Map TBD Break (as needed) 2:00 PM NRC Presentation on Source Term Members of the Public 3:30 PM Opportunity for Public Comment All 3:50 PM Closing Remarks NRC/NEI 4:00 PM Meeting Adjourn 2

U.S. NUCLEAR REGULATORY COMMISSION CATEGORY 1 PUBLIC WORKSHOP ON SPENT FUEL PERFORMANCE MARGINS LIST OF ATTENDEES March 25 - 26th, 2020 Name Organization Andrea Kock U.S. Nuclear Regulatory Commission (NRC)

Chris Regan NRC Tara Inverso NRC Yoira Diaz NRC Paul Kallan NRC Donald Chung NRC Don Algama NRC John McKirgan NRC Jorge Solis NRC Meraj Rahimi NRC Joann Ireland NRC Timothy McCarthy NRC John Wise NRC Ghani Zigh NRC Chris Bajwa NRC Jennifer Dulzell NRC Daniel Forsyth NRC Eliezer Goldfeiz NRC Richard Jervey NRC Caylee Kenny NRC Richard Lee NRC Haile Lindsay NRC Jason Piotter NRC April Smith NRC Jeremy Smith NRC Brian Wagner NRC Veronica Wilson NRC Donnie Harrison NRC David Decker NRC Jimmy Chang NRC Rod McCullum Nuclear Energy Institute (NEI)

Mark Richter NEI Kris Cummings Curtis Wright Jana Bergman Curtis Wright Tom Tramm Certrec David Tomlinson Dominion Energy Aladar Csontos Electric Power Research Institute (EPRI)

Hatice Akkurt EPRI Keith Waldrop EPRI Enclosure 2

Jeremy Renshaw EPRI Jack Desando Exelon Nancy Buschman Department of Energy (DOE)

Ned Larson DOE Michael Ford Ford ES&H Solutions Debu Majumdar Holtec International Stefan Anton Holtec International Steve Frishman Nevada Agency for Nuclear Project Brady Hanson Pacific Northwest National Laboratory Kevin Braico PG&E Richard Hagler PG&E Don Shaw TN Orano Rick Migliore TN Orano Venkata Venigalla TN Orano Andrea Jennetta Platts Glenn Schwartz PSEG Nuclear Samuel Durbin Sandia National Laboratories Sylvia Salzstein Sandia National Laboratories Paul Plante The Yankee Companies Steven Baker Transware Zita Martin TVA Robert Quinn Westinghouse John Phabe Westinghouse Kale Walker Public Marvin Lewis Public 2

U.S. NUCLEAR REGULATORY COMMISSION CATEGORY 1 PUBLIC WORKSHOP ON SPENT FUEL PERFORMANCE MARGINS On March 25 - 26, 2020, the U.S. Nuclear Regulatory Commission (NRC) held a Category 1 public workshop with the Nuclear Energy Institute (NEI) and other industry representatives, to discuss NEIs White Paper on Spent Fuel Performance Margins (White Paper) (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19318D971). This workshop built upon discussions held during the January 22, 2020, public workshop (summary available at ADAMS Accession No. ML20028F277) and focused on two technical areas: thermal margins and source terms. The goal of the workshop was to align on the problem statement, requested regulatory products, and next steps for the associated recommendations Approximately 64 people, including NRC staff, industry and members of the public, participated in the meetings via Skype and bridgeline.

The staff participated in NEIs presentation on its plans for a subset of recommendations listed in the white paper under Category 1, Actions that industry can take within the confines of existing regulations and guidance. The NRC presented on a recommendation in Category 2, Actions that NRC can take by tailoring their regulatory guidance as well as their review and inspection practices to recognize the existence of performance margin.

In the morning session on March 25, 2020, NEI presented opening remarks on its goals for workshops on the White Paper:

  • Utilize risk principles and graded approach wherever possible to optimize focus on safety significant issues.
  • Recognize that when large safety margins are known to exist, both preparers and reviewers should be able to accept small uncertainties without additional analyses.
  • Create deliverables that will change both NRC staff and industry licensing practices.
  • Build into new practices an understanding of the performance record achieved through over 30 years of experience with dry storage.
  • Achieve a regulatory transformation that focuses on safety and optimizes resources.

Industry then presented its RIRP on how to develop an industry best practices guide for thermal modeling, including the following industry-led milestones:

  • Identify the current industry issues regarding the implementation of the current best practices guidance.
  • Using the identified recommendations from the Thermal Modelling and Decay Heat Phenomena Identification and Ranking Tables (PIRTs) (Recommendation IV-1), create guidance for a risk- informed approach.
  • Develop a Topical Report.
  • Submit the Topical Report to NRC for review, approval and endorsement as part of a durable licensing approach that recognizes and enables use of thermal margins The NRC and NEI determined that these recommendations should be discussed in more detail at a future workshop.

Enclosure 3

Next industry presented on the Spent Fuel Performance and Waste Science and Technology (SFWST) perspectives on thermal modelling for storage and transportation of commercial spent fuel. Below is a summary of the presentation:

  • Thermal modeling is mature, and the physics and phenomena well understood.
  • Inputs to the models are typically conservative and biased, such that predicted temperatures are considerably higher than actual temperatures.
  • Temperatures are important because they drive degradation phenomena.
  • Peak cladding temperature (PCT) represents a very small fraction of total cladding surface temperature distribution.
  • From a cladding perspective, degradation effects may be present across a continuum of temperatures and there is no cliff edge effect at PCTs greater than 400°C.

In the afternoon session, the industry presented the proposed Table of Contents (TOC) for the Thermal Fuel Performance Topical Report. Both NRC and industry agreed the TOC was in its early stages. From this discussion, NRC and industry agreed that there should a future workshop on the topic of PIRT to further discuss the gross rupture performance.

At the end of the day, the NRC staff provided an opportunity to the public to provide any comments or questions. There were three comments from the public that were out of scope to the topics discussed at the meeting. However, NRC staff asked the members of the public to write their questions to the NRC and the NRC would respond to their questions.

In the morning of March 26, NEI presented its plans to address recommendations related to source terms, including the following highlights:

  • Industry would work to establish a set (or sets) of accetable input parameters, assumptions, and codes for source term calculation. For cask loading, this should:

o Result in source terms close to best estimate since subsequent analyses using the source terms already include conservatisms.

o Provide clarification on where parameter values are taken from and what, if any, adjustments needs to be applied.

o Allow for simplified source term analyses, unless simplifications would result in significant conservatisms.

Next NEI discussed a road map on source terms, specifically, recommendations III-1 and III-2.

The discussion focused on the differences between the evaluations documented as part of the safety evaluations (FSAR), and those performed to support cask loading.

In the afternoon, the NRC presented its draft RIRP on Recommendation III-1. The NRC indicated that it was developing options for transformative review approaches and would present those options during a workshop in Summer 2020.

At the end of the meeting, the NRC staff provided an opportunity to the public to provide any comments or questions. There were three comments from the public that were that were addressed at the meeting.

2

Summary Table:

March 25-26 Workshop on Spent Fuel Performance Margins Topic Recommendation Lead Problem Statement (short) Desired Regulatory Product Next Milestone Thermal Best Practices NEI Ensure gross rupture does not

  • Establish performance * (NEI Action) Evaluate Recommendations IV-Margins Guide1 happen; ensure compliance metric (could be a 1 through IV-5 and revise, as necessary.

with 10 CFR 72.122(h); separate working group Provide updated, documented incorporate results of EPRI activity) recommendation.

PIRTs to focus on inputs that matter most.

  • Best practices Issue draft PIRT reports.
  • Define fuel performance document
  • Conduct focused public workshop (with metric (e.g., temperature, appropriate subject matter experts (e.g.,

stress, combination of

  • Topical report fuels, criticality, retrievability, repackaging both). experts) to ensure mutual understanding of
  • Establish modeling gross rupture interpretation (72.122(h)).

techniques to meet o NEI to provide presentation of historical performance metric and interpretation, including how the create best practices interpretation has changed over time.

(margin, inputs). o NEI to document any suggested changes (This activity will address to interpretation, with basis for changes.

White Paper o NRC to review and provide feedback on Recommendations IV-1 industry presentation. NRC will provide through IV-5.) overview on areas impacted by gross rupture requirement.

  • Conduct focused public workshop on potential performance metrics (subset of white paper participants).2 1

Title likely to change as a result of public meeting discussion.

2 Thermal margins will no longer be a topic on the April 15-16, 2020, workshop agenda to allow time for these indicated milestones to evolve.

Enclosure 4

Source Conservatisms NEI Incorporate knowledge of Industry report documenting * (NEI lead) Discuss public workshop feedback Terms Roadmap spent fuel performance compilation of information and adjust approach for bifurcation suggestion margins to enhance industry and conclusions. NRC (licensing versus implementation)

(Recommendation implementation consistent with would review and (as III-1 and III-2) NRC regulations/guidance and appropriate) issue letter * (NEI lead) Provide more detailed draft focus on items of highest indicating that the report is document (publicly) safety significance. consistent with existing guidance/regulations.

  • Conduct follow-on public workshop Ensure implementation is informed by certification process. (And vice versa.)

Identify whether significant margin exists and can be captured during design certification or implementation activities.

Source Review Approach NRC Identify and evaluate Revised guidance. NRC to develop options for revising review Terms (Recommendation transformative approaches and approach and associated guidance, with pros III-3) develop review guidance and cons.

based on known NRC to conduct a public workshop to obtain conservatisms and appropriate feedback on options.

level of review within the

  • NRC selects optimal option and develops defined source terms. As part review criteria.

of this effort, NRC will include thermal technical experts.

2

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