Surging demand for generative artificial intelligence and data centers, among other drivers, in recent years has led to a revived interest in nuclear energy. While large nuclear power plants provide about 20% of our country’s electricity, progress is being made by the federal government and the private sector to bring small nuclear reactors, namely microreactors, to market.
What Are Microreactors?
Microreactors are a subset of nuclear reactors distinguished by their size. By way of comparison, conventional large reactors can generate over 1,000 megawatts electric (MWe) of electricity, and small modular reactors (SMRs) typically are defined as generating up to 300 MWe, whereas microreactors are often viewed as those generating less than 10 MWe.
Microreactors are sometimes considered as a subset of SMRs, but they differ from most SMRs in various ways, including their ability to be manufactured as "essentially complete" reactors in a separate facility. Unlike SMRs, microreactors can be mobile, meaning that some are being designed to be transported—with or without nuclear fuel—from the facility where they are manufactured to the site where they will be operated (and potentially other locations after the first), as opposed to having to be transported in several components and assembled at a single site.
Progress on Licensing and Development of Microreactors
Congress and the Nuclear Regulatory Commission (NRC) have taken steps in recent years to facilitate developing smaller reactor technologies, including microreactors. Since 2020, the NRC has been actively studying and developing the regulatory framework needed to license and ultimately deploy microreactors, and it has made this research available to the public in the form of white papers, including Policy and Licensing Considerations Related to Micro-Reactors and Micro-Reactor Licensing and Deployment Considerations: Fuel Loading and Operational Testing at a Factory. Congress then enacted the Accelerating Deployment of Versatile, Advanced Nuclear for Clean Energy (ADVANCE) Act in July 2024.
The ADVANCE Act directs the NRC to modernize and expedite the licensing process for advanced reactors, including microreactors, while maintaining the NRC’s commitment to safety. The Act also authorizes exploring national security applications for microreactors and encourages public-private partnerships to bring microreactor technologies to market.
Another key development for advancing microreactors was the Department of Defense (DoD) breaking ground on Project Pele at the Idaho National Laboratory (INL) in September 2024. Launched by the DoD’s Strategic Capabilities Office, Project Pele’s goal is to “design, build, and demonstrate a prototype mobile nuclear reactor” after the results of a 2016 study showed that “battlefield energy usage will likely significantly increase over the next few decades.” The fully-assembled reactor is scheduled to be transported to INL in 2026.
Additionally, earlier this month, the DoD’s Defense Innovation Unit (DIU) announced that eight companies are eligible to receive awards to provide commercially available dual-use microreactor technology at various DoD installations. The announcement marks the most recent development in the Advanced Nuclear Power for Installations (ANPI) program. DIU launched ANPI in partnership with the Army and the Air Force in 2024 with the goal of having two microreactors operating on US military bases by 2030.
New Developments on Microreactors
The NRC held a public meeting on April 10, 2025 to discuss the current and future status of microreactors. The meeting featured two panels, one with industry stakeholders and another with NRC staff, and included an opportunity for each NRC commissioner to ask questions in response to the panelists’ prepared comments.
Themes stressed at the meeting included the need for clarity and efficiency on the licensing path for microreactors and the national and economic security interests that can be served by microreactors. Below are some of the other key points discussed at the meeting:
- Chairman David Wright asked the panelists to speak to supply chain constraints that could impact the deployment timing of microreactors so the NRC can ensure that, consistent with its new mission statement, NRC licensing will not be the “long pole in the tent.”
- Commissioner Matthew Marzano emphasized the importance of exploring flexibility in the NRC’s regulatory frameworks to allow for licensing of microreactors, stressing that they “have the potential to not only provide clean electricity, to meet increasing demands . . . but they also offer a potential solution to achieve deep decarbonization of our larger energy system that powers our industries and our manufacturers.”
- Commissioner Annie Caputo also expressed an openness to streamlining the regulatory approvals needed to license microreactors, attributing the NRC’s ability to make the process more efficient to the risk profile of microreactors being “dramatically lower” than conventional reactors.
- Commissioner Christopher Hanson questioned how the differences with respect to the design of microreactors should lead the NRC to adapt its regulatory framework.
- NRC staff announced the launch of the Integrated Microreactor Activities Plan, which includes actions to “enhance the flexibility of the regulatory framework to support the diverse technologies and deployment models being considered by microreactor developers and potential applicants.” The plan aligns with Section 208 of the ADVANCE Act, which directs the NRC to develop and implement guidance related to microreactors across eight different areas.
The NRC plans to continue to build on the above issues discussed at the April 10 meeting with a series of follow-on stakeholder meetings. Ongoing efforts by several organizations within and without the federal government to license microreactors reflect a commitment to advancing nuclear technology while ensuring public safety. As the regulatory framework continues to evolve, microreactors hold the promise of providing reliable and resilient energy solutions for a variety of applications.
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