With concrete already being poured, this startup’s molten salt–cooled reactors could be the first to deliver cheaper, safer nuclear power.
Like many new nuclear startups, Kairos promises a path to reliable, 24/7 decarbonized power. Unlike most, it already has prototypes under construction and permits for several reactors.
Kairos made last year’s list because of a safer design for small modular reactors that produce power from nuclear fission. The company uses molten salt to cool its reactions and transfer heat, rather than the high-pressure water that’s used in existing fission reactors. The company was moving fast but cautiously, planning a series of non-nuclear prototypes to explore how best to pump this special coolant, a mixture of fluorine, lithium, and beryllium.
That iterative process continues today, with the recent installation of a non-nuclear reactor vessel for Kairos’s third test unit at the historic Oak Ridge nuclear site in Tennessee. The unit will test the handling of the coolant and the company’s innovative fuel—golfball-sized pebbles that package tiny seeds of uranium within a series of carbon and ceramic shells. This fuel was developed by the United Kingdom and the US Department of Energy (DOE), which has committed up to $303 million to support the construction of a reactor called Hermes, currently underway at the site.
