Two plants with SMRs are operational in China and Russia today, and other early units will likely follow their example and provide electricity to the grid. In China, the Linglong One demonstration project is under construction at a site where two large reactors are already operating. The SMR should come online by the end of the year. In the US, Kairos Power recently got regulatory approval to build Hermes 2, a small demonstration reactor. It should be operating by 2030.

One major question for smaller reactor designs is just how much an assembly-­line approach will actually help cut costs. While SMRs might not themselves be bespoke, they’ll still be installed in different sites—and planning for the possibility of earthquakes, floods, hurricanes, or other site-specific conditions will still require some costly customization. 

Fueling up

When it comes to uranium, the number that really matters is the concentration of uranium-235, the type that can sustain a chain reaction (most uranium is a heavier isotope, U-238, which can’t). Naturally occurring uranium contains about 0.7% uranium-235, so to be useful it needs to be enriched, concentrating that isotope.