Licensing Requirements for Microreactors and Other Reactors with Comparable Risk Profiles

The Breakthrough Institute, an independent non-profit research organization, supports the development of Part 57 as a risk-informed, performance-based licensing framework for high-volume deployment of microreactors and other reactors. They recommend clarifying the rule's purpose as a high-volume licensing pathway, aligning its tools with Part 53, and establishing clear transferability mechanisms between the two frameworks.

The Union of Concerned Scientists opposes the proposed rule, arguing that it is unnecessary, lacks clear definitions for "microreactors," and risks allowing larger, higher-risk reactors to qualify for a more lenient licensing regime. They specifically criticize the fuel mass limits as being too high and call for more stringent entry criteria, including power rating limits and robust lifecycle security requirements.

The Nuclear Energy Information Service (NEIS), a nuclear power watchdog and environmental organization, opposes the proposed rule and urges the NRC to terminate the rulemaking process. They argue that the proposal allows for dangerous "self-regulation," fails to address systemic safety concerns regarding mobile and autonomous reactors, and ignores the complications of radioactive waste.

The Abundance Institute, Last Energy, and Valar Atomics support the NRC's proposed rule to modernize nuclear licensing for microreactors, praising its risk-informed and performance-based approach. However, they urge the Commission to further streamline the process by recognizing a "Tier 1" category for very low-risk reactors that fall below the statutory threshold for "utilization facilities."

Radiant Industries, Inc., a clean energy startup, supports the proposed rule for licensing microreactors because it provides a practical pathway for mass-manufacturing and deployment. The company offers specific technical suggestions to streamline the regulatory process, clarify definitions for irradiated fuel, and adjust transportation dose rate limits to reduce costs and logistical burdens.

Core Power (US) Inc. supports the proposed rule, emphasizing its technology-inclusive and performance-based framework for maritime nuclear technologies. They advocate for specific regulatory innovations, such as general licenses for shipyard construction, flexible decommissioning trust fund access, and role-based fitness-for-duty programs tailored to maritime operations.

Amentum, a global engineering and operations services prime contractor, strongly supports the proposed Part 57 rulemaking for microreactors. They argue that the risk-informed framework is essential for accelerating the deployment of privately financed nuclear capacity on Department of Defense (DoD) installations to support national security missions and grid resilience.

The commenters strongly oppose the proposed rule, arguing that it creates a dangerous "fast track" for licensing microreactors by significantly reducing regulatory oversight and safety requirements. They express concerns regarding the lack of public comment periods, the risks of transporting nuclear waste, and the potential for security vulnerabilities in smaller reactor designs.

The Connecticut Nuclear Energy Advisory Council expresses concern that the proposed rule for microreactors introduces too many departures from long-established safety practices, such as the single-failure criterion and defense-in-depth principles. They argue that the emphasis on rapid deployment and autonomous operations could compromise safety margins and public confidence, and they urge the NRC to maintain rigorous, independent, and conservative oversight.

The commenter argues that the proposed Part 57 rule lacks sufficient clarity and completeness regarding physical security requirements compared to the established Part 73.100 framework. They specifically highlight concerns regarding the graded approach, reliance on offsite responders, omission of vehicle-borne threat protections, and the inconsistent dose reference values between safety and security events.