French firm seeks permission to build fast-neutron nuclear reactor

French start-up Stellaria has taken a significant step by submitting an application to French nuclear authorities seeking permission to build its Alvin prototype, the world’s first fast-neutron molten salt reactor (MSR), with a planned startup in 2030. This move marks Stellaria’s transition from concept development to a formal regulatory phase, elevating the company to the status of a nuclear operator. The application includes detailed safety analyses, environmental impact assessments, and plans for decommissioning, emphasizing the reactor’s design features such as four containment barriers, underground installation, and the use of molten fluoride salts as coolant at low pressure, which contribute to its safety and operational stability. The Stellarium reactor, developed by Stellaria—a spin-off from CEA and Schneider Electric—operates using fast neutrons and molten salt fuel, aiming to validate the MSR concept through experimental testing. MSRs are notable for their potential to use thorium fuel cycles and operate under low pressure, offering safety and efficiency advantages. Stellaria