Current U.S. fast-moving advanced reactor design and regulatory environment dictates that the commercialization of these reactors increasingly involves navigating multiple regulatory and oversight frameworks, evolving design concepts, and varying facility missions. For emerging reactor developers, the “path to licensing” is not linear; it is shaped by project objectives, regulatory authority, design demonstration needs, and the intended function of the facility. This paper presents insights and lessons learned from the licensing strategy development for a sodium-cooled advanced reactor program that experienced evolving design and project pivots and different oversight pathway evaluations under both the U.S. Department of Energy (DOE) and Nuclear Regulatory Commission (NRC). Through this development, the analysts at Aalo Atomics found that paths including DOE reactor demonstrations and future NRC licensing each have distinct safety philosophies, analytical expectations, and technical precedents. The determination of the licensing pathway therefore has direct implications for the depth, scope, and structure of required safety and risk analyses.

Throughout the Aalo reactor project evolution, different safety and licensing approaches were considered, including NRC research reactor pathways; and risk-informed, performance-based frameworks and deterministic DOE nuclear safety-basis processes; hazard and failure mode categorizations. The depth, scope, and need for hazard analysis, deterministic safety analysis, and probabilistic risk assessment (PRA) were found to be highly sensitive to three attributes: (1) facility type (experimental versus commercial), (2) mission (irradiation testing, power production, or demonstration), and (3) regulatory or oversight authority.

The paper discusses how PRA, hazard identification, and accident analysis scope and requirements varied depending on the licensing strategy selection. In some cases, traditional deterministic safety-basis approaches drove analysis depth; in others, risk-informed methods enabled graded application of requirements. The experience at Aalo Atomics highlights how early regulatory engagement, clear definition of facility mission, and alignment between design maturity and safety analysis expectations are critical to avoiding rework and inefficient analytical effort.

As a focus of the paper, we provide key insights on:
(1) aligning safety analysis depth with hazard category and regulatory framework,
(2) identifying where PRA meaningfully supports design and licensing decisions,
(3) managing design and project evolution without destabilizing the safety case, and
(4) structuring internal processes to remain adaptable across regulatory pathways.
These lessons contribute to the broader discussion within the risk community on scalable, performance-based licensing strategies for advanced reactors and underscores the importance of integrated regulatory, design, and risk-informed decision-making from project inception.