Licensing Guidance Frameworks

Objective / Purpose

Guidance is focused on surveying and developing sufficient general design criteria such that an AR design complies with licensing requirements developed by the NRC, or another regulatory body such as the CNSC (Canada) or the IAEA (Europe/ Asia). It should also be mentioned that while the IAEA provides useful information regarding the licensing of advanced reactors across different countries, unlike the NRC the IAEA does not produce regulations and does not have any formal research groups to review its findings.

Scope

The NRC has developed several Reg Guides that apply to the adaptation of the Code of Federal Regulations (CFR) 10 Part 50 and 52 for the licensing of non-LWR designs. Additionally, 10 CFR part 54 is currently under development for how it applies to advanced reactor licensing. Please visit the NRC Regulations Title 10 homepage for the full directory of title 10 regulations.

Guidance

In the US, NRC Reg Guide 1.233 [9] provides guidance to applicants who are seeking licenses to operate advanced non-light water reactor nuclear power plants and Reg Guide 1.232 [12] provides guidance on the licensing of non-LWRs from Appendix A of Title 10 Part 50 CFR. Although 10 CFR 50 Appendix A provides some guidance in establishing principal design criteria (PDC) for non-LWR designs, it is the applicant’s responsibility to develop the PDC for its facility based on its design, using generic design criteria, non-LWR design criteria, or other design criteria as the foundation. Similar to Reg Guide 1.232, INL/EXT-14-31179 [12] describes design guidance related to advanced non-light water reactors.

In Canada the CNSC framework for risk-informed decision-making is described in REGDOC-3.5.3 [18]. In 2019, the CNSC and the U.S. NRC signed a memorandum of cooperation (MOC) [19] to increase collaboration on technical reviews of advanced reactor and small modular reactor technologies.

Outside of North America, the IAEA has provided some guidance in developing methodologies and safety requirements for AR designs. In particular, the current IAEA safety approach is based on four main pillars that are discussed in IAEA Safety Standard No. SSR-2/1 [14]:

• Qualitative Safety Objectives
• Fundamental Safety Functions
• Defense in Depth
• Probabilistic Safety Assessment

Additionally, the IAEA conducted a case study published as TECDOC-1366 [15] “Considerations in the Development of Safety Requirements for Innovative Reactors: Application to Modular High Temperature Gas Cooled Reactors” which concludes that the existing safety approach’s primary concepts could be suitable for new plants if correctly interpreted and formulated. TECDOC-1570 [16] proposes a new safety approach for ARs based on the review of existing pillars to include any consideration of new technologies and incorporation of probabilistic considerations. In particular, the Safety Goals are identified in terms of consequences as a function of likelihood of occurrence.

Across nations, there has been some established common ground as the safety case demonstration specified in the IAEA developed framework for advanced reactors that will be deployed in different countries and is intended to share a similar framework in identifying events, classifying them, and ensuring that potential consequences of plant accidents meet a consistent set of regulatory standards.

In current practice, advanced reactor vendors develop a generic design phase PRA or a reference plant PRA that is dependent on the reactor design. A Level 1 PRA or both Level 1 and Level 2 PRAs may be requested by the applicable regulatory authority for each new reactor project. A Level 3 PRA is typically not developed or requested by the regulatory authorities for new reactors. However, a Level 3 PRA could support the definition of exclusion zones [25]. In the US, the Licensing Modernization Project (LMP) has developed a methodology that uses standard safety analyses like Process Hazards Analysis (PHA) and PRA to support various safety applications during the design and development process of advanced reactors, including evaluating design alternatives, selecting Licensing Basis Events (LBEs), classifying structures, systems, and components (SSCs), and assessing the adequacy of defense-in-depth.