Small Modular Reactors (SMRs) have attracted attention to nuclear energy that hasn’t been seen in decades. The phrase “SMR” now appears in landmark federal legislation, bills to lift state nuclear construction bans, and deployment plans for data centers, military bases, and disaster relief zones. It all sounds like progress, but is it possible that this phrase has accidentally restricted development?
The International Atomic Energy Agency (IAEA) defines SMRs as advanced nuclear reactors with power output up to 300 megawatts per module, roughly one-quarter the capacity of traditional large reactors. They’re called modular because components can be factory-built and transported to sites rather than constructed on-site like traditional plants, promising faster deployment and lower upfront costs.
The phrase “advanced nuclear” refers to a much broader range of technologies. Small modular reactors are certainly included under the advanced nuclear umbrella, but so are innovative ideas like floating nuclear plants, microreactors to replace diesel generators, high-temperature reactors providing industrial process heat, and fast reactors that can consume nuclear waste as fuel. Most importantly, advanced reactors don’t have to be small. They can be just as large as traditional light water reactors, or even larger. The confusion between “advanced nuclear” and “SMRs” was mostly semantic until it became legal language – then it got expensive.
Illinois banned new nuclear construction in 1987, but in 2023, legislation to lift the moratorium passed both chambers of the state legislature. The bill would have allowed new advanced reactor construction, opening pathways for next-generation nuclear development. That is, until Governor J.B. Pritzker vetoed it.
The bill that Pritzker signed limited reactors to 300 megawatts. He was concerned that “advanced reactors” represented a category so broad that it could make way for large reactors like the AP1000 to be built in the state. SMRs were the hot new technology said to revolutionize energy markets, and bigger reactors were seen as politically scary. The entire purpose of lifting the nuclear construction moratorium was to enable new advanced reactor deployment and position Illinois as a leader in next-generation nuclear energy. Instead, the fixation on SMRs as a magic category excluded the technologies most likely to succeed in the near term.
The only advanced nuclear technology that’s achieved commercial operation in the United States so far is Westinghouse’s AP1000. These reactors have passive safety systems, similar to many Gen III+ designs, and produce over 1,000 megawatts of capacity. Four units are operating at Plant Vogtle in Georgia right now.
TerraPower, another advanced reactor developer that is currently constructing non-nuclear infrastructure in Wyoming, aims for 345 megawatts. Their Natrium reactor integrates molten salt energy storage to provide dispatchable output, and is backed by Bill Gates’s billions, paving the way for commercial success within a matter of years. These technologies are advanced by all definitions, but don’t fit into the neat package that earns the SMR stamp of approval.
Any reactor with feasible design improvements should be developable under advanced nuclear legislation. Fixation on “SMR” as the category that defines innovation creates arbitrary cutoffs that omit viable technologies, and correcting these subtle exclusions starts with us—stakeholders, advocates, and industry professionals who want progress over particularity.
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