Are small modular reactors a breakthrough or still a promise?
The first US small modular reactor project, from NuScale, was cancelled in 2023 after its cost estimate nearly doubled.
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Small modular reactors are a promise that has not yet been proven at scale in the West. An SMR is a fission reactor of under 300 megawatts of electric power, built from modular parts to make construction faster and easier to scale. Proponents claim that standardized modules made in a factory would be cheaper than one-off giant plants.
The idea is attractive for several reasons. systems that work without external power or human action are expected to make the reactors safer, though that is true of most modern reactor designs, not only SMRs. Interest has come from technology companies: in October 2024 Google agreed to commission multiple SMRs from Kairos for its AI data centers, with the first due in 2030, and in 2024 Amazon announced four Xe-100 reactors in Washington state.
Proponents expect
- Standard modules built in a factory
- Faster, simpler construction
- systems
Critics say
- Cost-effective only at large volume
- About 3,000 units needed (BASE calculation)
- Some types may make more waste per unit
But the first US project fell through. The Carbon Free Power Project would have used six NuScale reactors. The target price after subsidies rose from 58 dollars per in 2021 to 89 dollars in 2023, and the project was cancelled in November 2023, after its cost had risen from 5 billion to 9 billion dollars and customers pulled out. Critics say modular building pays off only for large numbers of the same type, and a German federal agency calculated that about 3,000 units would need to be produced to be worthwhile.
Elsewhere, Russia has operated a floating plant, Akademik Lomonosov, commercially since 2020, and, as of October 2026, China's Linglong One demonstration reactor is due to start by the end of the year.
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Recap
SMRs promise factory-built, standard reactors, but their economics depend on building many of them.
💡 A trick to remember it · Small and modular is the promise, but the factory only pays off when it runs flat out.
Surprising fact · Russia has run a floating nuclear plant, Akademik Lomonosov, commercially since 2020.
Sources (2)
No source, no claim. Every fact in this lesson (16 claims) cites at least one of these.