ML22186A166
| 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) | |
Text
1 0 C F R Pa r t 5 3 L i c e n s i n g a n d R e g u l a o n o f A d v a n c e d N u c l e a r R e a c t o r s J u l y 6, 2 0 2 2 Advisory Committee on Reactor Safeguards (ACRS)
Full Committee Meeting
A C R S F u l l C o m m i t t e e M e e t i n g J u l y 6, 2 0 2 2 Part 53 Framework B Overview
Agenda Overview of Part 53 Structure Comparison of Part 53 Frameworks Discussion of Key Subparts Guidance Development Framework Integration 3
Part 53 Licensing Frameworks Framework A o Probabilistic risk assessment (PRA)-led approach o Functional design criteria o Top-down approach for meeting high-level safety criteria and defining key safety functions Framework B o Traditional use of risk insights o Principal design criteria o Bottom-up approach based on well-established safety functions o Includes an Alternative Evaluation for Risk Insights (AERI) approach Subpart A - General Provisions Subpart B - Safety Requirements Subpart C - Design Requirements Subpart D - Siting Subpart E - Construction/Manufacturing Subpart F - Operations Subpart G - Decommissioning Subpart H - Application Requirements Subpart I - License Maintenance Subpart J - Reporting Subpart K - Quality Assurance Subpart N - Definitions Subpart O - Construction/Manufacturing Subpart P - Operations Subpart Q - Decommissioning Subpart R - Application Requirements Subpart S - License Maintenance Subpart T - Reporting Subpart U - Quality Assurance 4
Quantitative Risk Information Bounding Approaches Traditional Use of PRA Risk-Informed Continuum Part 53 Licensing Frameworks 5
Part 53 Subpart Comparison Subpart Title Framework A Subpart Framework B 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 Definitions specific to Framework B o
Anticipated operational occurrence (AOO) o Design bases o
Reactor coolant pressure boundary o
Safety-related structures, systems, and components (SSCs)
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
- Primary containment leakage
- Environmental qualification of electrical equipment 8
- 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 Subpart R - Licenses, Certifications, and Approvals 9
Framework B Guidance Development Many Framework A and B guidance development activities are linked May involve updates or supplements to existing guidance covering existing regulatory frameworks 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
- Siting
- Seismic Design Criteria
- Requirements for Operation Evaluate other provisions for potential alignment
- Definitions
- General Provisions Commonalities in Subpart A Continue consideration of stakeholder feedback 11
Final Discussion and Questions 12
A C R S F u l l C o m m i t t e e M e e t i n g J u l y 6, 2 0 2 2 Part 53, Framework B, Subpart R:
Alternative Evaluation for Risk Insights (AERI)
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 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)
- Use of Probabilistic Risk Assessment Methods in Nuclear Regulatory Activities (60 FR 42622; August 16, 1995)
- Provides sufficient risk information to inform licensing decisions
- Right-sizes the effort required to evaluate risk
- 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)
Evolution of the AERI Alternative Approach 15 Uses risk insights to enhance regulatory efficiency.
16 16 Perform transient and accident analyses Perform design basis accident radiological consequences analyses Identify and analyze the bounding event Finish PRA development Select licensing basis events Select DBAs Classify SSCs Continue design and licensing activities Evaluate defense-in-depth Comprehensive and systematic initiator search and event sequence delineation without preconceptions or reliance on predefined lists Select licensing events Select licensing framework Perform transient and accident analyses Perform design basis accident radiological consequences analyses Elect to develop PRA Finish PRA development Continue design and licensing activities Continue design and licensing activities A
Parts 50 and 52 with LMP Part 53 Framework A Parts 50 and 52 without LMP Part 53 Framework B B
C D
E F
G H
I J
K L
M N
O yes no Applicant decision PDG-1413, Technology-Inclusive Identification of Licensing Events for Commercial Nuclear Plants PDG-1414, Alternative Evaluation for Risk Insights (AERI) Framework Licensing Modernization Project (LMP) guidance - NEI 18-04, Rev. 1, as endorsed in RG 1.233 AERI entry condition met?
P yes no Q
Licensing Frameworks - Risk Evaluation Perspective Alternative Evaluation for Risk Insights Notes:
1)
Each step builds on all of the preceding steps (considers all information available at that point) 2)
Feedback loops (e.g., the impact of design revisions) are not shown AERI Q1 Develop demonstrably conservative risk estimate using the bounding event Q2 Search all event sequences for severe accident vulnerabilities Q3 Develop risk insights by reviewing all event sequences Q4 Assess defense-in-depth adequacy by reviewing all event sequences ONLY for Part 53 Framework B 16
Proposed AERI Entry Condition 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 The AERI entry condition is not a safety or siting criterion!!!
18 reference point is the exclusive area boundary (EAB) reference point = 100 meters QHO = 2E-6 If the reference point is the EAB, then need to credit accident frequency when EAB radius > 100 meters Premise: It is feasible to identify a bounding event such that the consequence of any event sequence is 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 sequence frequencies and the consequence of the bounding event.
Note: It is only necessary to estimate the sum of the event sequence frequencies; it is not necessary to estimate each individual event sequence frequency using a PRA.
Development of the AERI Entry Condition
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
- Appendix A (Comprehensive Search for Initiating 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 21 Licensing Framework Initiating Event Search and Event Sequence Delineation Licensing Event Identification AERI Approach Acceptability Approach Acceptability Approach Acceptability Parts 50 and 52 with LMP PDG-1413 PRA Standards
- NLWR - RG 1.247 NEI 18-04, Rev. 1, as endorsed in RG 1.233 QA Program Part 50, App. B n/a n/a Part 53, Framework A QA Program Part 53, Subpart K Parts 50 and 52 without LMP PDG-1413 QA Program Part 50, App. B Part 53, Framework B (PRA)
QA Program Part 53, Subpart U Part 53, Framework B (AERI)
Quality Assurance (QA) Program Part 53, Subpart U PDG-1414 QA Program, Part 53, Subpart U For dose/consequence and demonstrably conservative risk assessments, use PRA Standards
- NLWR - RG 1.247
Discussion 22
ACRS Advisory Committee on Reactor Safeguards AERI Alternative evaluation for risk insights AOO Anticipated operational occurrence CFR Code of Federal Regulations DBA Design basis accident EAB Exclusion area boundary FR Federal Register LMP Licensing Modernization Project LWR Light water reactor Acronyms NEI Nuclear Energy Institute NRC U.S. Nuclear Regulatory Commission PDG Pre-decisional draft regulatory guide PRA Probabilistic risk assessment QA Quality assurance QHO Quantitative health objective RG Regulatory guide SSCs Structures, systems, and components TEDE Total effective dose equivalent 23