The Nuclear Regulatory Commission (NRC) on Oct. 22 finalized a rule that allows commercial nuclear reactor applicants to use analyses, test data, and other technical evidence from reactor demonstrations previously authorized by the Department of Energy (DOE) or Department of War (DOW) to support license applications.
The measure establishes a more direct means of incorporating federal demonstration results into commercial reactor safety reviews, potentially reducing duplicative technical evaluations as developers seek to move advanced nuclear technologies from testing to commercial deployment.
The final rule, which amends provisions in 10 CFR Parts 50 and 53, explicitly allows applicants to reference prior federal authorizations when demonstrating that a reactor design can perform its required safety functions. While the NRC has historically considered testing, analyses, and operating experience in licensing reviews, the amendments establish a specific regulatory provision for information gathered from reactors that DOE or DOW previously authorized and that have been tested and demonstrated the ability to function safely. The extent to which applicants can rely on that evidence will depend on how closely the demonstration results correspond to the proposed commercial design and whether the information satisfies applicable NRC requirements.
The NRC called the rule the first major change to its reactor regulations finalized under Executive Order (EO) 14300, which President Donald Trump signed on May 23, 2025. Section 5(d) of the order calls for an expedited pathway to approve reactor designs that DOE or DOW have tested and that have demonstrated the ability to function safely. It directs that NRC review of such designs “shall focus solely on risks that may arise from new applications permitted by NRC licensure, rather than revisiting risks that have already been addressed in the DOE or DOD processes.”
“This rule delivers the EO 14300 vision for an expedited path from DOE and DOW projects to NRC commercial licensing,” NRC Chairman Ho K. Nieh said in the agency’s announcement. “High-quality applications showing how DOE and DOW results apply to NRC requirements will help us review them more efficiently.”
A New Licensing Pathway
The amendments establish an additional option for demonstrating reactor safety under the NRC’s existing commercial licensing requirements, including the frameworks established under Parts 50 and 52 and the risk-informed, technology-inclusive framework under Part 53. They do not establish a separate licensing process or exempt developers from the statutory and regulatory requirements that govern commercial nuclear facilities.
Under Part 50, Section 50.43(e) governs the demonstration of safety functions for reactor designs that differ significantly from light-water reactor designs licensed before 1997, or that use simplified, inherent, passive, or other innovative means to accomplish those functions. The existing provisions establish two alternatives: applicants may demonstrate the performance of individual safety features, assess their interdependent effects, and provide sufficient data to validate analytical tools through analyses, testing, or operating experience, or they may rely on acceptable prototype plant testing across specified operating and accident conditions.
The final rule adds Section 50.43(f), which explicitly provides that an application under Section 50.43(e) “may include consideration of relevant information gathered from a utilization facility that has been previously authorized by the Department of Energy or the Department of Defense and that has been tested and has demonstrated the ability to function safely.” The regulatory text retains the “Department of Defense” title for consistency with existing NRC regulations. Applicants must identify how attributes of that prior authorization satisfy NRC regulations, including the safety demonstration requirements established under Section 50.43(e).
A corresponding revision to Section 53.440(a)(1) permits similar use of federal demonstration evidence under Part 53, where applicants must demonstrate that reactor design features can satisfy defined functional criteria for design-basis accidents and other licensing-basis events. Those demonstrations must consider interdependent effects throughout the commercial nuclear plant and the range of conditions under which the relevant safety features must function throughout the plant’s lifetime.
In both cases, the provisions give applicants an additional means of substantiating their safety cases, potentially allowing the NRC to rely on relevant technical evidence already developed through a federal demonstration program. However, the agency emphasized that applicants remain responsible for establishing how prior authorization results satisfy its requirements, including where the demonstrated design differs from the proposed commercial reactor. Those differences could include changes in reactor design, functionality, associated hazards, siting information, or underlying safety assumptions.
The NRC acknowledged this limitation in the final rule, explaining that the scope of a DOE or DOW authorization or associated testing may not fully represent a commercial reactor configuration or the breadth of analyses necessary for an NRC licensing basis. Consequently, applicants may use prior demonstration evidence to satisfy some requirements, but they must address any remaining gaps to ensure full compliance with NRC requirements.
The agency also stressed that the rule does not transfer regulatory authority from the NRC to DOE or DOW or permit the NRC to dispense with its own safety assessments.
“Nothing in this rule delegates to DOE, DOW, or any other agency the NRC’s functions to evaluate a request for NRC approval, and nothing in this rule allows the NRC to forego an independent review,” the final rule states.
The NRC said it will continue to conduct the independent assessments necessary to confirm whether applicants have satisfied requirements under the Atomic Energy Act of 1954 and NRC regulations. However, where an applicant justifies the applicability and relevance of information from a prior DOE or DOW authorization, the agency said it may be able to tailor the focus and depth of its review.
Federal Reactor Demonstrations Already Underway
The new rule comes as DOE and the U.S. Army are advancing separate reactor demonstration programs that could provide technical evidence for future commercial licensing applications. Although neither program automatically qualifies its participants for expedited NRC review, both are generating or preparing to generate the testing, operational, and safety data that developers may eventually seek to use under the new provisions.
DOE’s efforts have already produced several milestones. Following the launch of its Reactor Pilot Program in June 2025 and the selection of 11 initial projects from 10 companies that August, four DOE-authorized reactors achieved zero-power fueled criticality by July 4, 2026, exceeding the three-reactor target established under President Trump’s May 2025 executive order on reactor testing. The demonstrations included Antares Nuclear’s Mark-0 on June 4, Valar Atomics’ Ward 250 on June 18, Deployable Energy’s Unity on June 30, and Aalo Atomics’ Aalo-X Critical Test Reactor on July 4.
The projects advanced through different DOE authorization pathways, however. Deployable Energy’s Unity experiment, for example, proceeded through the Nuclear Energy Launch Pad at Idaho National Laboratory, not the initial Reactor Pilot Program. Meanwhile, Oklo’s Groves Isotope Test Reactor in Lockhart, Texas, became the fifth DOE-authorized reactor to achieve criticality on Aug. 5. That low-power, water-cooled facility supports isotope-production development and is distinct from Oklo’s Aurora commercial power reactor.
While these criticality experiments establish a self-sustaining fission chain reaction and provide valuable reactor-physics data, they do not demonstrate sustained electricity production or the performance of a complete commercial reactor plant. Nevertheless, developers are already examining how the resulting technical evidence could support future licensing.
Meanwhile, the Army is pursuing a more direct route toward electricity production through its Janus Program, developed in partnership with the Defense Innovation Unit (DIU). In August, the Army selected five developers for initial microreactor projects at military installations: Antares Nuclear at Fort Bragg, North Carolina; BWXT Advanced Technologies at Fort Campbell, Kentucky; General Atomics Electromagnetic Systems at Fort Hood, Texas; Radiant Industries at Fort Benning, Georgia; and Westinghouse Government Services at Fort Drum, New York.
Under the initiative, the Army plans to commit up to $2.2 billion through milestone-based agreements spanning fiscal years 2027 through 2031. The contractor-owned and operated reactors are intended to supply reliable electricity to military installations, and the Army is targeting operation of at least one reactor by Sept. 30, 2028, consistent with the deployment objective established under Executive Order 14299. The program is also intended to support the development of commercially marketable microreactor technologies, although the Army does not expect all five initial projects to begin operating by that deadline.
The Army Reactor Regulatory Office will oversee safety authorizations for the defense reactors, creating another potential source of federally evaluated reactor performance data. For developers seeking to deploy similar technologies commercially, however, those authorizations will not replace NRC licensing. The extent to which they can support future applications will depend on the relevance of the demonstration evidence and the developers’ ability to address differences in reactor configurations, operating conditions, sites, and associated hazards.
The NRC’s final rule will take effect 30 days after publication in the Federal Register, which the agency expects during the week of Oct. 26.
Editor’s Note: This is a developing story. POWER will update this report as additional information becomes available.
