Stellaria is developing the Stellarium — a fourth-generation fast-neutron molten salt reactor that regenerates its fuel during operation making it self-sufficient for over 20 years while reducing long-lived nuclear waste. Co-founded by CEA and Schneider Electric, Stellaria raised €23 million in 2025 led by At One Ventures and Supernova Invest alongside CEA Investissements and Schneider Electric. The company received €10 million in France 2030 programme funding. In February 2026 Stellaria submitted a prototype application (Alvin) to French authorities. The company signed a power pre-order agreement with data centre operator Equinix.