ML22160A039
| ML22160A039 | |
| Person / Time | |
|---|---|
| Issue date: | 06/10/2022 |
| From: | Robert Beall NRC/NMSS/DREFS/RRPB |
| To: | |
| Beall, Robert | |
| Shared Package | |
| ML20289A534 | List:
|
| References | |
| 10 CFR Part 53, NRC-2019-0062, RIN 3150-AK31 | |
| Download: ML22160A039 (33) | |
Text
This overview white paper is being released to support ongoing public discussions concerning the development of preliminary proposed rule language. This whi te paper has not been subject to complete NRC management or legal review, and its contents sh ould not be interpreted as official agency positions. The NRC staff continues to work on the preliminary proposed rule language described in this document and continues to welcome pu blic participation in these the rulemaking activities.
Part 53 Framework B Development Process and Provisions Overview
The Nuclear Regulatory Commission (NRC) staff is developing opt ional regulatory frameworks to support eventual licensing of commercial nuclear plants thro ugh the proposed addition of a new part (Part 53) in Title 10 of the Code of Federal Regulations (10 CFR).1 The existing regulatory frameworks in 10 CFR Part 50 (Part 50) and 10 CFR Pa rt 52 (Part 52) are currently being used for licensing new reactor technologies, but they wer e developed largely to accommodate the design and licensing of large, light-water reac tors (LWRs). Part 53 would provide technology-inclusive regulations using methods of evaluation that are flexible and practicable for application to a variety of advanced reactor te chnologies, such as high-temperature gas and molten salt reactors. This would, in turn, help to reduce the need for non-LWR applicants to apply exemptions from certain existing LWR-sp ecific requirements.
Preliminary proposed Part 53 language includes two distinct lic ensing framework options:
- Framework A: Requirements would support an iterative approach to design and licensing where a Probabilistic Risk Assessment (PRA) is used i n a leading manner.
Functional design criteria informed by a PRA are established to ensure that high-level safety and design requirements are satisfied. Framework A lever ages many of the principles developed as part of the licensing modernization pro ject as outlined in Nuclear Energy Institute Report 18-04,2 and NRC Regulatory Guide (RG) 1.233. 3
- Framework B: Requirements would support a traditional approach to design and licensing where deterministic safety analyses are complemented by risk insights; risk insights may also be used to confirm the results of traditional safety analyses. Principal design criteria are established in the initial stages of design and licensing and subsequent design activities are performed to ensure that these criteria are met.
Framework B also provides for the optional use of an Alternate Evaluation for Risk Insights (AERI) approach if certain criteria are satisfied to d emonstrate that the bounding accident of such a facility would be of very low consequence.
1 This rulemaking was initiated, in part, in response to Congressional direction in the Nuclear Energy Innovation and Modernization Act, Pub. L. No. 115-439, § 103(a)(4), 132 Stat. 5565, 5572 (Jan. 14, 2019)
(codified at 42 U.S.C. § 2133 note).
2 Nuclear Energy Institute Technical Report 18-04, Revision 1. Risk-Informed Performance-Based Technology Inclusive Guidance for Non-Light Water Reactor Licensing Basis Development. August 2019 (ML19241A336).
3 Regulatory Guide (RG) 1.233, Revision 0. Guidance for a Technology-Inclusive, Risk-Informed, and Performance-Based Methodology to Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light Water Reactors. June 2020 (ML20091L698).
Framework A preliminary proposed rule language development is l argely complete. The second consolidated iteration of preliminary proposed rule language fo r Framework A was issued in May 2022 (Agencywide Documents Access and Management System (AD AMS) Accession No. ML22125A000).
The NRC staff is preparing a consolidated draft proposed rule p ackage with both frameworks to be provided to the Commission in February 2023. In the interim, the NRC staff continues to provide opportunities for stakeholders to provide feedback and comments on preliminary proposed rule language4 and supports additional stakeholder interactions through publi c meetings.
Background
Framework B was developed in response to stakeholder feedback r egarding the need for additional flexibility in the use of PRA in Part 53. Framework B development was also motivated by stakeholder feedback suggesting that some reactor vendors ma y initially pursue international markets where licensing frameworks are informed by internationa l safety standards and guidelines that more closely align with traditional paradigms i n Part 50 and Part 52. Therefore, an internationally licensed design could subsequently be licens ed domestically under a traditional framework, such as Framework B, without the need fo r major changes to the design approach.
Efforts to develop a traditional licensing framework in Part 53 began in mid-to late-2021 with the Part 5X effort which proposed technology-inclusive alternativ es to some of the technical requirements in Parts 50 and 52. The initial iteration of the P art 5X rule text was included within the Part 53 consolidated draft preliminary proposed rule text p ackage issued in February 2022 (ADAMS Accession No. ML22024A066). The Part 5X rule text, inclu ding feedback received on the Part 5X rule text during stakeholder interactions in 2021, was leveraged to develop certain Framework B technical content of application requirements. For example, the accident analysis and initiating event requirements in paragraph § 53.4730(a)(5) of the draft preliminary proposed rule text was informed by the Part 5X effort.
Development Methodology
The NRC staff employed the following approach for developing Fr amework B requirements:
- Adopt Framework A requirements when the Framework A requiremen ts are independent of the analysis methodology (e.g., decommissioning).
o The NRC staff used direct cross-references to Framework A, whe re possible.
o Where direct cross-references could not be used, Framework A p rovisions were copied to Framework B with updated internal cross-references, t erminology, etc.
- Assess if existing requirements in Parts 50 and 52 are technol ogy inclusive. If so, adopt them directly by copying the existing requirements into Framewo rk B. In some instances, provisions from Parts 50 and 52 were not copied into Framework B, but were used by
4 For information on how to submit comments go to https://www.regulations.gov and search for Docket ID NRC-2019-0062
drafting conforming changes in the existing requirements and in cluding a reference to these requirements in Framework B.
- Develop unique, technology-inclusive requirements correspondin g, where appropriate, to existing requirements in Parts 50 and 52. Consider state-of-pra ctice technical and policy initiatives and, as appropriate and consistent with Commission policy, approaches used in international standards.
A table summarizing the results of this development process, in cluding the source of Framework B requirements and reason for deviations from the source, as ap plicable, is provided in. Enclosure 1 reveals that a majority of Framework B preliminary proposed rule language is derived from Framework A or Parts 50 and 52. The NR C staff notes that there are instances where Frameworks A and B are intended to be identical or similar, but may have diverged slightly due to the timing between when the most recen t iteration of each framework was released. These deviations will be reconciled when the fram eworks are merged.
Structure
Like Framework A, Framework B was developed to establish a stan dalone set of requirements covering the entire lifecycle of a commercial nuclear plant. Th erefore, Framework A was used as a starting point for establishing the structure of Framework B. As shown in Table 1, Framework A and B structures are largely parallel.
Table 1: Part 53 Organization
Subpart Title Framework A Framework B Subpart Subpart General Provisions Subpart A (Common)
Technology-Inclusive Safety Requirements Subpart B Note (1)
Design and Analysis Requirements Subpart C Siting Requirements Subpart D Note (2)
Definitions Note (3) 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 Subpa rt T Quality Assurance Criteria Subpart K Subpart U Notes:
(1) Framework B does not include separate subparts for safety and design requirements. These are largely captured by the requirements in Subpart R in a manner similar to how technical requirements are captured for the various application types in Parts 50 and 52 as part of the technical content of application requirements for a given application type.
(2) Framework B does not include a separate subpart for siting requirements. The siting requirements in 10 CFR Part 100 are used instead, consistent with the treatment of siting in Parts 50 and 52.
(3) The most recent iteration of Framework A issued in May 2022 does not include a separate subpart for framework-specific definitions. It is expected that definitions specific to Framework A will be included within an existing Framework A subpart as the preliminary proposed rule language is further refined.
Subpart A: General Provisions Provides a scope and purpose statement, definitions of terms co mmon to Frameworks A and B, and other provisions common to both frameworks (e.g., written c ommunications, employee protection, specific exemptions).
Subpart N: Definitions Provides definitions that are unique to Framework B.
Subpart O: Construction and Manufacturing Requirements Provides requirements regarding construction and manufacturing activities; requirements are consistent with Framework A Subpart E except for internal refer ences.
Subpart P: Requirements for Operation Provides requirements regarding plant operations, including pla nt personnel, maintenance, and programs. The structure of Subpart P parallels Framework A Subp art F in with some exceptions. These exceptions include certain programmatic requi rements derived from the traditional licensing frameworks in Parts 50 and 52 (e.g., asse ssing maintenance effectiveness, environmental qualification of electrical equipment).
Subpart Q: Decommissioning Requirements Provides decommissioning requirements that are consistent with Framework A Subpart G, except for internal references.
Subpart R: Licenses, Certifications, and Approvals Provides design and licensing requirements for the various appl ication types (early site permit, standard design approval, design certification, manufacturing l icense, construction permit, operating license, and combined license). Subpart R is analogou s to Framework A Subpart H, but includes many of the technical requirements foundational an d unique to Framework B (e.g.,
accident analyses, risk evaluations). For additional informatio n see the Technical Requirements section below.
Subpart S: Maintaining and Revising Licensing Basis Information Provides requirements for maintaining licensing basis informati on and is structured identically to Subpart I in Framework A, with some exceptions. Certain require ments have been derived from Parts 50 and 52 (e.g., changes to a facility as described in th e final safety analysis report without prior NRC approval) or adapted to account for Framework B-specific features (e.g.,
maintenance of a risk evaluation to include AERI).
Subpart T: Reporting and Other Administrative Requirements Provides reporting and administrative requirements that are ana logous to Subpart J in Framework A, with some exceptions. Certain provisions were adap ted from Part 50 and 52 to account for the framework-specific approaches to structures, sy stems, and components (SSCs) classification (e.g., immediate notification requirements from § 50.72 and licensee event reports from § 50.73).
Subpart U: Quality Assurance Criteria Provides quality assurance requirements for the design, manufac ture, construction, and operation of certain SSCs. Subpart U is structured similar to Framework A Subpart K, and as Subpart K, the criteria have been sourced from Part 50 Appendix B.
Technical Requirements
In contrast to the structure of technical content of applicatio n requirements in Part 50 and 52, Subpart R features a consolidated listing of technical requirem ents in § 53.4730 that are later referenced, as appropriate, in application-specific sections. T he requirements in § 53.4730 are largely derived from the technical content of application requi rements for a combined license (COL) application in § 52.79 because these requirements general ly encompass the requirements for other application types. The following example illustrates how the Framework B approach compares to the organization of technical content of application requirements in Parts 50 and 52.
Design Certification (DC) and COL applicants under Part 52 are required to provide an analysis and description of the equipment and systems for combustible ga s control by § 52.47(a)(12) and § 52.79(a)(8), respectively. The requirements in each of th ese two paragraphs in Part 52 are identical. Framework B includes a singular, identical, comb ustible gas control requirement in
§ 53.4730(a)(7) that is referenced in the technical content of application requirements for a DC and COL in § 53.4839 and § 53.5016, respectively.
A matrix summarizing § 53.4730 technical requirements reference d by each application type is provided in Enclosure 2.
Alternate Evaluation for Risk Insights (AERI)
The NRC staff recognized that the broad spectrum for which appl icants may eventually pursue licensing under Framework B could include facilities that would have maximum accidents of very low consequence (e.g., low power microreactors). Consideri ng this potential, the NRC staff has proposed an AERI approach for developing risk insights that would support licensing of these facilities. The AERI approach permits the use of alternat e methods for developing risk insights (e.g., qualitative approaches) in lieu of a PRA if an applicant can satisfy the criteria in subparagraph § 53.4730(a)(34)(ii). Applicants and licensees usi ng the AERI approach would still be required to maintain alternate risk evaluations in acc ordance with the requirements of
§ 53.6052, similar to the requirements for maintaining a PRA th at are currently applied to licensees under § 50.71(h).