The CEA, France’s Alternative Energies and Atomic Energy Commission, has spun out two start-ups—Hexana and Stellaria—to develop small fourth-generation modular nuclear reactors (SMRs).

Hexana aims to implement a fast neutron and sodium-cooled reactor, integrating a high-temperature storage device. This installation will be based on a set composed of two small reactor units (400 MW_th each) supplying a heat storage device, useful to best manage the variations in electrical power needed by industries.

An adjoining conversion system will allow it to produce electricity as needed and flexibly to compete with gas-fired power plants but also to supply heat directly to nearby energy-intensive industries. With electricity and heat, companies could capture CO₂ and produce steam, hydrogen, and synthetic fuels.

Fast neutron and sodium heat transfer reactants are of major interest in the management of nuclear materials: they operate without natural or enriched uranium but with depleted uranium combined with plutonium from the reprocessed fuels of the French nuclear fleet (MOX).

Stellaria aims to develop a molten chloride salt reactor (MSR). MSRs use molten salts as the heat transfer fluid. The liquid fuel can remain almost continuous in the reactor core. The reactor proposed by Stellaria will be very compact (250 MW_th in 4m³) and, like Hexana, will be able to use a diversified range of nuclear fuels (uranium, plutonium, MOX, minor actinides, or even thorium), thus fitting into the French strategy of closing the cycle.