Explaining 10 CFR Part 57 – a new pathway for microreactors

sarahgibboney
Jul 7
4 min read

In the summer of 2025 the U.S. Nuclear Regulatory Commission (NRC) began work on 10 CFR Part 57, a rule that would create a dedicated licensing pathway for factory‑fabricated microreactors and other low‑consequence reactors. The regulation hasn’t yet appeared in the Federal Register (as of Jan 30 2026), but several public sources describe what is coming and why it matters.

Why now?

Executive Order 14300 (May 23 2025) requires the NRC to “establish a process for high‑volume licensing of microreactors and modular reactors” by allowing standardized applications, approvals and (where appropriate) general licenses. This mandate builds on the ADVANCE Act and recent energy‑security orders and reflects growing industry interest in microreactors.
The NRC’s July 14 2025 public meeting announcement states that the agency is developing a proposed rule to address licensing requirements for microreactors and other low‑consequence reactors. The meeting was held to gather stakeholder feedback because EO 14300 directs the Commission to consider general‑licensing approaches for these reactors.
NRC slides presented at the meeting explain that microreactors could support grids, remote communities and industrial applications, and that a more efficient, streamlined licensing process is needed to handle more than 15 potential designs.

What will Part 57 do?

The NRC’s July 2025 presentation outlines several rule fundamentals and additional details:

Goal: Create a licensing process that protects public health, safety, common defense and the environment, and completes safety and environmental reviews (with public engagement) before a site is chosen. Site reviews would then verify that specific site characteristics fit within the design envelope.
Entry criteria: The framework would be risk‑informed and performance‑based; entry criteria under consideration include dose‑acceptance criteria, maximum hypothetical accident analyses and limits on special nuclear material.
Design criteria: Safety and security attributes would include reactivity control, heat removal, fission‑product retention, shielding and effluent controls. The framework would treat safety and security together and could draw from existing standards for non‑power reactors.
Additional considerations: The rule may address manufacturing (factory construction and testing), fuel possession, transportation, construction, operation, onsite storage, inspections, safeguards/security, emergency preparedness, risk analysis methods, staffing, oversight and decommissioning. Security‑by‑design principles are expected; NRC presentations note that Part 57 will be a risk‑informed, technology‑inclusive regulatory framework alongside Part 53.

Human‑factors experts also stress that Part 57 should explicitly address new operational concepts for small and microreactors—minimal staffing, extensive automation/AI, remote operations and surveillance of passive safety systems.

Who will be affected?

Microreactor developers and vendors: Companies planning factory‑fabricated microreactors or other “low‑consequence” reactors will need to meet the new criteria and may benefit from standardized, high‑volume licensing.
Applicants seeking non‑site‑specific licenses: Part 57 envisions completing many safety and environmental evaluations up front, prior to site selection, which could shorten project timelines.
Existing nuclear vendors and utilities: The rule could allow certain reactors to be regulated through general licenses rather than individual, site‑specific licenses. This may impact how utilities integrate microreactors into their portfolios.
Communities near proposed sites: Public engagement remains part of the process, and the NRC has held public meetings and will solicit comments when the draft rule is published.

Timeline and Next Steps

NRC staff held public meetings in July 2025 to introduce the rule and gather feedback. According to a Nuclear Innovation Alliance report, the NRC is developing draft rulemaking for “low‑consequence reactors,” with draft language due to the Commission in March 2026 and the final rule published by November 2026 or sooner.
The NRC’s Advisory Committee on Reactor Safeguards (ACRS) noted that the staff held a closed session on Part 57 draft language on Oct 7 2025 and that the ACRS plans a full‑committee meeting and letter once the rule is published for public comment (expected March 2026). The committee also plans to review specific sections of EO 14300 (5(b)–5(g)) related to reactor security.

Where to get information

ADAMS documents: The NRC’s public meeting materials are available through the Agencywide Documents Access and Management System (ADAMS). Key accession numbers include ML25192A037 (July 14 2025 slide deck) and ML25192A134 (public meeting announcement and agenda). These documents outline the scope and concepts of the rule.
Regulations.gov docket: When the proposed rule is published, it will be posted on the Federal Register and the Regulations.gov docket NRC‑2025‑0379 for public comment. Stakeholders can subscribe for notifications on that docket.
NRC microreactors page: The NRC’s Microreactors – Rulemaking page and the Effectiveness, Efficiency and Timeliness Initiatives section provide context on the ADVANCE Act and EO 14300 and will be updated as more information becomes public.
Contact points: NRC staff members George Tartal and Elijah Dickson are listed as contacts for the July 2025 meeting.

Takeaway

10 CFR Part 57 isn’t yet published, but the NRC’s presentations and meeting notes reveal an ambitious rule aimed at right‑sizing regulation for microreactors. It seeks to enable high‑volume licensing through risk‑informed, performance‑based requirements, address unique aspects of factory‑fabricated reactors (transportability, remote operation, automation) and integrate security and human‑factors considerations from the beginning. Watch for the draft rule in early 2026 and participate in the public comment process to help shape the future of microreactor regulation.