Efficient and Effective Advanced Reactor Design and Licensing Basis Development Requires Codifying a Rationalist Approach

For nuclear energy generating systems to remain an option for energy generation, a variety of designs/technologies are needed, and they must be commercially viable, socially acceptable, and regulatory licensable. The regulatory body and its regulatory framework are an important factor that impacts all three of these attributes; therefore, it is critical for the nuclear industry to work collaboratively with the regulator to ensure an agile, predictable, and resilient regulatory framework is available to facilitate efficient and effective licensing that is not a barrier to innovation by imposing unnecessary burden. In the United States, the current licensing pathways for nuclear reactors are largely based upon a structuralist approach, which places emphasis on specific outcome requirements that have been prescribed. An example of this philosophy in the US Nuclear Regulatory Commission framework is the General Design Criteria, which prescribe functions and programmatic controls that are identified to be important to safety based upon industry experience with large light water reactors. This structuralist construct was developed over many years to provide licensing predictability while providing adequate technical basis for the regulator to discharge its regulatory obligation. By contrast, a rationalist approach places emphasis on performance requirements and systematic processes to derive solutions that satisfy these performance requirements. Such an approach enables a regulatory framework to be agile, predictable, and resilient for a variety of technologies, not just technologies that have produced extensive operating experience. Such a framework also facilitates achieving the following goals: 1. Cohesive requirements and regulatory oversight programs to be set for all stages of a nuclear power plant life cycle. 2. Coherent and consistent requirements and regulatory oversight programs for different designs based on design specific safety margins, thereby minimizing unbalanced regulatory requirements for different designs resulting in unfair competitive advantage. 3. Development and deployment of owner-controlled programs to improve efficiency and effectiveness of programmatic requirements and regulatory oversight programs while reducing staffing level. This paper will discuss the importance of a rationalist approach to the success of advanced reactors and provide examples of processes that support a technology-inclusive, holistic, and integrated framework, including those that produce a safety case that is risk-informed, performance-based, and supported by insights from Probabilistic Risk Assessment. (author)