If you have been trying to follow recent headlines about nuclear reactor development in the United States and feel confused, you are not alone, and your confusion is well earned. One news story announces the granting of hundreds of millions of dollars in new federal funding under programs with names like ARDP (Advanced Reactor Demonstration Program) or RPP (Reactor Pilot Program). Another reports that a reactor has been “authorized” at Idaho National Laboratory or Oak Ridge, Tennessee. A third describes a construction permit moving forward at the Nuclear Regulatory Commission. Still another mentions the Department of Defense sponsoring a microreactor for use at a military base. 

Each story invokes an alphabet soup of acronyms — DOE, NRC, DoD, LPO, PTC, PPA, GAIN, FOAK — and each sounds, in its own way, like progress. But it can be difficult, even for people within the nuclear industry, to determine exactly what is happening. Has a reactor been approved to operate? Has it merely been funded? Is it licensed? And which federal agency, exactly, is exercising legal authority?

Until recently, the answer to those questions was much simpler. For most of the civilian nuclear era, approval of new reactors in the United States revolved around a single institution: the Nuclear Regulatory Commission. If a reactor was going to be built and operated, especially to generate electricity for the grid, it required a Nuclear Regulatory Commission license issued under the Atomic Energy Act. That basic framework still exists. But it no longer tells the whole story.

Today, authority over reactor deployment in the United States is no longer concentrated in one agency. Instead, it is distributed across three: the Department of Energy (DOE), the Department of Defense (DOD), and the Nuclear Regulatory Commission (NRC). Each acts under different statutory mandates, uses different regulatory tools, and supports or approves different kinds of nuclear activity. The resulting system is not incoherent, but it is complex and layered. And for those trying to assess the true state of American nuclear progress, it is often confusing.

For decades, the structure of nuclear approval aligned neatly with the dominant use case for reactors: large, light-water plants built by utilities to sell electricity into regulated or wholesale markets. In that world, the NRC’s licensing authority under the Atomic Energy Act, implemented through Parts 50 and 52 of Title 10 of the Code of Federal Regulations (C. F. R.), was the central gateway. Other agencies mattered, but they played secondary roles.

That world is in the process of changing. Modern advanced reactors are smaller, more diverse in design, and often intended for purposes other than generating electricity. Some are built primarily to demonstrate technology. Others are aimed at industrial heat, remote or facility-specific power, or defense resilience. At the same time, federal policymakers have placed renewed emphasis on speed, learning-by-doing, and strategic competition. As a result, the United States has increasingly come to rely on multiple federal pathways to move nuclear projects forward. The NRC remains central, but it is no longer alone.

The most significant shift has occurred at the Department of Energy. DOE does not license reactors in the NRC sense. It cannot grant a commercial operating license under the Atomic Energy Act. Yet DOE has always possessed something that, in certain contexts, is equally consequential — statutory authority over federal nuclear facilities and the authority to fund nuclear projects and approve nuclear reactors located on them.

When reactors are sited at national........

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