NRC proposes Part 57 framework to speed microreactor licensing

The Nuclear Regulatory Commission’s proposed Part 57 could change microreactor deployment from a years-long licensing slog into something that looks much closer to an industrial rollout. By creating a technology-specific path for reactors at 100 MWe or smaller, the agency is trying to spare developers from forcing tiny, factory-built units through rules built for gigawatt-scale plants, and it is putting hard numbers on the payoff: a projected $3.76 billion to $11.84 billion in combined industry and agency savings, with construction-permit and operating-license timelines as short as 6 to 12 months.

That matters because licensing has been one of the biggest bottlenecks holding back the sector’s move from prototypes to projects. NRC Chairman Ho K. Nieh said the framework is meant to modernize licensing for advanced reactors and is designed around safety, scale and speed. The proposal is framed as risk-informed and flexible, but still anchored to public health, safety and security. It also fits inside a broader federal push under Executive Order 14300 and the ADVANCE Act, which has already pushed the NRC toward lower fees and faster reviews.

Part 57 is not just a new label on old paperwork. The NRC said it would allow approval of fleets of identical reactors, permit appropriate use of alternative design standards, streamline environmental reviews for projects with minimal impacts and create a path for limited construction before a full NRC permit is issued. Those changes would hit hardest in the places that have struggled most under existing licensing routes: remote sites, military installations and industrial users that want small, repeatable units rather than one-off custom plants.

The agency is moving while the pipeline is still forming. NRC staff said they were aware of more than 15 potential microreactor design applications, and in July 2025 staff identified the central policy goals as consequences-based regulation, a rapid and repeatable licensing process and performance-based graded requirements. The commission also settled three policy matters in June 2025 to help factory-built microreactor deployment, and in December 2025 staff issued a memo on oversight during the operational phase.

That makes Part 57 look less like a standalone proposal and more like the first credible regulatory unlock for the microreactor market. The U.S. Department of Energy’s Reactor Pilot Program selected 11 advanced reactor projects and is aiming for at least three test reactors to reach criticality by July 4, 2026. DOE also picked Westinghouse Electric Company and Radiant Industries for the first DOME fueled microreactor experiments, which could begin as early as spring 2026 at Idaho National Laboratory. If Part 57 survives the comment period, due May 4 under Docket ID NRC-2025-1503, and the Federal Register notice slated for May 6, the licensing clock for the smallest reactors could finally start to match the industry’s construction ambitions.