DOE announces NEPA exclusion for advanced reactors

The background: Like many recent changes in the world of nuclear regulation, this news stems from one of the four nuclear-related executive orders signed by President Trump in May 2025. Executive Order (EO) 14301, “Reforming Nuclear Reactor Testing at the Department of Energy,” directed the energy secretary to “take action to reform the Department’s rules governing compliance with [NEPA]” in order to “eliminate or expedite the Department’s environmental reviews,” in part by “creating categorical exclusions as appropriate for reactors within certain parameters.”

On categorical exclusions, EO 14301 adds that “decades of research and engineering have produced prototypes of advanced nuclear technologies that incorporate passive safety mechanisms, improve the physical architecture of reactor designs, increase reactor operational flexibility and performance, and reduce risk in fuel disposal.”

In response, on June 30, 2025, the DOE released updated information on its NEPA rulemaking to enact some of the changes called for by EO 14301.

New change: This newest DOE announcement further develops these changes, making official the called-for categorical exclusion for advanced reactors. The creation of this categorical exclusion means that certain advanced reactor projects may not require the preparation of an environmental assessment or environmental impact statement.

It is critical to note that not all advanced reactor projects will automatically be exempted from standard NEPA procedures. “In deciding whether to apply this categorical exclusion to a particular project, DOE would consider each of the conditions in the categorical exclusion itself,” along with NEPA implementing procedures. This consideration would take into account “whether extraordinary circumstances exist such that a normally excluded action may have a significant environmental effect,” the FR announcement states.

In other words, projects will be exempted from lengthy NEPA procedures on a case-by-case basis rather than through a blanket exemption. When deciding whether to grant a categorical exclusion for a project, the DOE may consult with the applicant; other federal agencies; external parties; state, local, or tribal governments; and other sources as needed.

Ultimately, the DOE will grant a categorical exclusion to a project only if its “fission product inventory, fuel type, reactor design, and operational plans” sufficiently reduce “the risk of adverse off-site consequences from the release of radioactive or hazardous materials.” The project must also demonstrate that any hazardous waste—including spent fuel—can be properly managed.

While advanced reactor projects have—so far—been for experimental, testing, and demonstration purposes, many companies are working to deploy these technologies for power production in the near-term. The DOE’s FR notice states that “the advanced fuel forms, inherently safe designs, and inventories of potential fission products associated with these reactors indicate that reactors in this category developed for additional purposes, such as power production and industrial applications, are also appropriate for this categorical exclusion.”

In preparing this change, the DOE consulted with the Department of Defense, the Nuclear Regulatory Commission, and the Council on Environmental Quality—a division within the Executive Office of the President established by NEPA.

What is an advanced reactor? Many words and phrases immediately come to mind when attempting to define the term “advanced reactor”: microreactor, small modular reactor, Generation IV, Generation III+, mobile reactor, non–light water reactor. These terms, of course, raise more questions than they answer and also lack specific, universally accepted definitions.

42 USC 16271 defines advanced reactors as fission reactors with “significant improvements compared to reactors operating on December 27, 2020.” Those improvements can fall into areas such as inherent safety features, lower waste yields, improved fuel performance, increased thermal efficiency, modular sizes, operational flexibility, and more. Also included in the U.S. Code’s definition are fusion reactors and radioisotope power systems.

The NRC defines advanced reactors as reactors that “differ from today’s reactors primarily by their use of inert gases, molten salt mixtures, or liquid metals to cool the reactor core. Advanced reactors can also consider fuel materials and designs that differ radically from today’s enriched uranium-dioxide pellets within zirconium cladding.”

For its part, the DOE’s new announcement says that advanced reactor projects “have key attributes such as safety features, fuel type, and fission product inventory that limit adverse consequences from releases of radioactive or hazardous material.”