ML22186A166

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NRC Staff Presentation Slides for 7/6/22, ACRS Full Committee Meeting - 10 CFR Part 53 Licensing and Regulation of Advanced Nuclear Reactors: Overview of Framework B Preliminary Proposed Rule Language and the Alternative Evaluation for Risk
ML22186A166
Person / Time
Issue date: 07/06/2022
From: Robert Beall
NRC/NMSS/DREFS/RRPB
To:
Beall R
References
10 CFR Part 53, NRC-2019-0062, RIN 3150-AK31
Download: ML22186A166 (23)
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Text

A d v i s o r y C om m i tte e on Re ac to r Safe guards (ACRS )

Full Committee Meeting 10 CFR Part 53 Licensing and Regula on of A dvanced Nuclear Reactors July 6, 2022

Part 53 Framework B Over view ACRS Full Committee Meeting July 6, 2022

Agenda

  • Overview of Part 53 Structure
  • Comparison of Part 53 Frameworks
  • Discussion of Key Subparts
  • Guidance Development
  • Framework Integration 3

Part 53 Licensing Subpart B - Safety Requirements Framework A Frameworks Subpart C - Design Requirements o Probabilistic risk assessment (PRA)-led approach Subpart D - Siting o Functional design criteria Subpart E - Construction/Manufacturing o Top-down approach for meeting Subpart F - Operations high-level safety criteria and Subpart G - Decommissioning defining key safety functions Subpart H - Application Requirements Subpart I - License Maintenance Subpart J - Reporting Subpart K - Quality Assurance Subpart A - General Provisions Framework B Subpart N - Definitions o Traditional use of risk insights Subpart O - Construction/Manufacturing o Principal design criteria Subpart P - Operations o Bottom-up approach based on Subpart Q - Decommissioning well-established safety functions Subpart R - Application Requirements o Includes an Alternative Evaluation Subpart S - License Maintenance for Risk Insights (AERI) approach Subpart T - Reporting Subpart U - Quality Assurance 4

Part 53 Licensing Frameworks Quantitative Risk Information Bounding Approaches Traditional Use of PRA Risk-Informed Continuum 5

Part 53 Subpart Comparison Framework A Framework B Subpart Title Subpart Subpart General Provisions Subpart A (Common)

Technology-Inclusive Safety Requirements Subpart B (Subpart R)

Design and Analysis Requirements Subpart C Siting Requirements Subpart D (Part 100)

Definitions - Subpart N Construction and Manufacturing Requirements Subpart E Subpart O Requirements for Operation Subpart F Subpart P Decommissioning Requirements Subpart G Subpart Q Licenses, Certifications, and Approvals Subpart H Subpart R Maintaining and Revising Licensing Basis Information Subpart I Subpart S Reporting and Other Administrative Requirements Subpart J Subpart T Quality Assurance Criteria Subpart K Subpart U 6

Subpart N - Definitions

  • Common definitions remain in Subpart A (§ 53.020) 7

Subpart P - Requirements for Operation

  • Structured similar to Subpart F in Framework A
  • Programmatic requirements for security, emergency preparedness, and radiation protection aligned with those in Framework A
  • Provisions for staffing, training, personnel qualifications, and human factors are largely equivalent between frameworks with the exception of generally licensed reactor operators.
  • Other requirements for operation informed by existing requirements applicable to applicants and licensees under Parts 50 and 52
  • Maintenance, repair, and inspection programs
  • Technical specifications
  • Fire protection
  • Environmental qualification of electrical equipment 8

Subpart R - Licenses, Certifications, and Approvals

  • Structured similar to Subpart H in Framework A
  • Process-related requirements in Subpart R are identical between the frameworks
  • Technical requirements informed by existing regulatory frameworks
  • Requirements captured in content of application sections
  • Technical content of application requirements consolidated in § 53.4730
  • Many requirements from Parts 50 and 52 translated to Framework B with select updates and modifications for technology-inclusiveness
  • Initiating event and accident analyses requirements evolved from initial Part 5X effort
  • Requirements in § 53.4730(a)(5) cover AOOs, design basis accidents (DBAs), beyond design basis events, severe accidents and chemical hazards
  • Generally aligned with current requirements and, as appropriate, incorporates international concepts on defense-in-depth.
  • Requirements for containment address the need for functional containment alternatives that may be employed by non-LWRs 9

Many Framework A and B guidance development activities are linked Framework B May involve updates or supplements Guidance to existing guidance covering existing regulatory frameworks Development Guidance for technical content of application requirements now part of Advanced Reactor Content of Application Project effort 10

Areas of Focus for Integration of Frameworks A and B Ensure consistency between parallel provisions Evaluate other provisions for potential alignment

  • Siting
  • Seismic Design Criteria
  • Requirements for Operation Commonalities in Subpart A
  • Definitions
  • General Provisions Continue consideration of stakeholder feedback 11

Final Discussion and Questions 12

Part 53, Framework B, Subpart R:

Alternative Evaluation fo r Risk Insights (AERI)

ACRS Full Committee Meeting July 6, 2022

Agenda

  • Evolution of the AERI Approach
  • AERI Entry Condition
  • Summary of PDG-1413, Technology-Inclusive Identification of Licensing Events for Commercial Nuclear Plants
  • Summary of PDG-1414, Alternative Evaluation for Risk Insights (AERI) Framework 14

Evolution of the AERI Alternative Approach

  • Evolution of the AERI approach is an example of modern risk-informed regulation:
  • Achieves the underlying purposes of Commission policy statements:
  • Policy Statement on the Regulation of Advanced Reactors (73 FR 60612; October 14, 2008)
  • Safety Goals for the Operation of Nuclear Power Plants (51 FR 28044; August 4, 1986 as corrected and republished at 51 FR 30028; August 21, 1986)
  • Severe Reactor Accidents Regarding Future Designs and Existing Plants (50 FR 32138; August 8, 1985)
  • Provides sufficient risk information to inform licensing decisions Uses risk insights to enhance
  • Right-sizes the effort required to evaluate risk regulatory efficiency.
  • Two pre-decisional draft regulatory guides (PDGs) have been developed to:
  • Clarify for potential applicants the logic and the expectations of the NRC staff
  • Address related ACRS recommendations to start with a blank sheet of paper (10/7/2019, 10/21/2020, 5/30/2021, and 10/26/2021) 15

Licensing Frameworks - Risk Evaluation Perspective H I Parts 50 and 52 with LMP Perform Perform design basis Continue design transient and accident radiological and licensing Part 53 Framework A accident analyses consequences analyses activities C D E F Select Finish PRA licensing basis Select DBAs Classify SSCs development events G

A Evaluate Comprehensive defense-in-and systematic depth initiator search and event B Select Notes:

sequence 1) Each step builds on all of the preceding steps (considers all information available at that point) licensing delineation framework 2) Feedback loops (e.g., the impact of design revisions) are not shown without preconceptions J K L M N or reliance on Select Perform Perform design basis yes Continue design Elect to Finish PRA predefined lists licensing transient and accident radiological and licensing develop PRA development events accident analyses consequences analyses activities Q AERI Parts 50 and 52 without LMP no Q1 Develop demonstrably Part 53 Framework B ONLY for Part 53 conservative risk estimate Framework B no using the bounding event Applicant decision Q2 Search all event O P sequences for severe Identify and yes Continue design AERI entry accident vulnerabilities PDG-1413, Technology-Inclusive Identification of Licensing Events for analyze the and licensing condition met? Q3 Develop risk insights by Commercial Nuclear Plants bounding event activities reviewing all event PDG-1414, Alternative Evaluation for Risk Insights (AERI) Framework sequences Q4 Assess defense-in-depth Alternative Evaluation adequacy by reviewing all Licensing Modernization Project (LMP) guidance - NEI 18-04, Rev. 1, as 16 endorsed in RG 1.233 for Risk Insights event sequences 16

Proposed AERI Entry Condition The AERI entry condition is not a safety or siting criterion!!!

53.4730(a)(34) Description of risk evaluation.

A description of the risk evaluation developed for the commercial nuclear plant and its results. The risk evaluation must be based on:

(i) A PRA, or (ii) An AERI, provided that the dose from a postulated bounding event to an individual located 100 meters (328 feet) away from the commercial nuclear plant does not exceed 1 rem total effective dose equivalent (TEDE) over the first four days following a release, an additional 2 rem TEDE in the first year, and 0.5 rem TEDE per year in the second and subsequent years.

  • Provides plants with flexibility in establishing their exclusion area boundaries (EABs) if the bounding events source term is small.
  • The 100-meter reference dose location was back-calculated from a scoping consequence model:

o 50-year dose = 27.5 rem TEDE o Conditional individual latent cancer fatality risk 2 x 10-6 per event o Meet the quantitative health objective (QHO) without developing a PRA to credit accident frequency in the risk estimate 17

Development of the AERI Entry Condition

  • Premise: It is feasible to identify a bounding event such that the If the reference point is the EAB, then need to credit consequence of any event sequence is accident frequency when EAB radius > 100 meters less than or equal to the consequence of the bounding event.
  • Implication: Risk is less than or equal to the product of the sum of event reference point is the sequence frequencies and the exclusive area boundary (EAB) consequence of the bounding event.
  • Note: It is only necessary to estimate QHO = 2E-6 the sum of the event sequence reference point = 100 meters frequencies; it is not necessary to estimate each individual event sequence frequency using a PRA.

18

Technology-Inclusive Identification of Licensing Events for Commercial Nuclear Plants (PDG-1413)

  • Formatted like a regulatory guide; currently a pre-decisional draft regulatory guide
  • Section A: Applies to light water reactors (LWRs) and non-LWRs licensed under Parts 50, 52, and 53 (Frameworks A and B)
  • Section B (Discussion):

o Identifies licensing events for each licensing framework o Provides historical perspectives (early licensing, development of the standard review plan) o Addresses ACRS recommendations to start with a blank sheet of paper (10/7/2019, 10/21/2020, 5/30/2021, and 10/26/2021)

  • Section C (Staff Guidance) provides an integrated approach for:

o Conducting a systematic and comprehensive search for initiating events o Delineating a systematic and comprehensive sets of event sequences o Grouping the lists of initiating events and event sequences into licensing events

o Reviews techniques for searching for initiating events and points the user to helpful references o Does not endorse or recommend any specific technique 19

Alternative Evaluation for Risk Insights (AERI) Framework (PDG-1414)

  • Formatted like a regulatory guide; currently a pre-decisional draft regulatory guide
  • Section A (Introduction): Only applies to LWRs and non-LWRs licensed under Part 53 Framework B
  • Sections B (Discussion) & C (Staff Guidance) - Components of the AERI approach:

o Identification and characterization of the bounding event Definition of a bounding event Multiple events may need to be considered as bounding events o Determination of a consequence estimate for the bounding event to confirm that the reactor design meets the AERI entry condition o Determination of a demonstrably conservative risk estimate for the bounding event to demonstrate that the QHOs are met Assumed frequency of 1/yr consistent with frequency of all event sequences for LWRs Applicant may use a lower frequency with justification o Search for severe accident vulnerabilities for the entire set of licensing events Definitions of severe accident and severe accident vulnerability o Identification of risk insights for the entire set of licensing events o Assessment of defense-in-depth adequacy for the entire set of licensing events 20

Revision to Improve Clarity: Applicability of Guidance to Licensing Frameworks Initiating Event Search and Event Sequence Delineation Licensing Event Identification AERI Licensing Framework Approach Acceptability Approach Acceptability Approach Acceptability Parts 50 and 52 QA Program with LMP NEI 18-04, Rev. 1, Part 50, App. B as endorsed in Part 53, RG 1.233 QA Program Framework A PRA Standards Part 53, Subpart K Parts 50 and 52

  • NLWR - RG 1.247 Part 50, App. B Part 53, Framework B PDG-1413 (PRA)

PDG-1413 QA Program, Part 53, Subpart U QA Program Part 53, Quality Assurance Part 53, Subpart U For dose/consequence and Framework B (QA) Program PDG-1414 demonstrably conservative risk (AERI) Part 53, Subpart U assessments, use PRA Standards

Discussion 22

Acronyms Advisory Committee on Reactor NEI Nuclear Energy Institute ACRS Safeguards NRC U.S. Nuclear Regulatory Commission AERI Alternative evaluation for risk insights PDG Pre-decisional draft regulatory guide AOO Anticipated operational occurrence PRA Probabilistic risk assessment CFR Code of Federal Regulations QA Quality assurance DBA Design basis accident QHO Quantitative health objective EAB Exclusion area boundary RG Regulatory guide FR Federal Register SSCs Structures, systems, and components LMP Licensing Modernization Project TEDE Total effective dose equivalent LWR Light water reactor 23

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