Stellaria seeks permission to build world’s first fast-neutron nuclear reactor
A French firm has submitted its application with local authorities, seeking approval to build an experimental fast-neutron reactor. Stellaria’s application concerns the siting and construction of its Alvin prototype, scheduled to start up in 2030.
The move aims to launch the test program that will definitively validate the concept.
The company is the first French start-up working on fast-neutron reactors to submit such an application.
Stellaria moves beyond the concept stage
“2025 marked a turning point for Stellaria. After a structuring fundraising round , followed by the signing of a first power pre-order agreement for our reactors with Equinix, the global leader in data centers, the submission of the DAC (Application for Authorization to Create) allows us to reach a new milestone,” said Nicolas Breyton, President of Stellaria.
“This step is decisive for Stellaria, as it validates the work carried out so far by its teams and partners, and fully commits the company to its responsibilities as a nuclear operator. By filing this application, Stellaria moves beyond the concept stage and enters a structuring regulatory phase, in which its fundamental choices are now set.”
Stellaria, a French start-up spun out of the CEA and Schneider Electric and specializing in fast-neutron molten salt nuclear reactors, submitted its Application for Authorization to Create (DAC) for its Basic Nuclear Installation (INB) Alpha to the French minister in charge of nuclear safety.
Implementation of Stellarium reactor
The step by Stellaria is a new milestone that represents a crucial step in the development of the French company and in the implementation of its Stellarium reactor, as it sets out the main principles of the project and officially elevates the start-up to the status of a nuclear operator.
The Application for Authorization to Create a Basic Nuclear Installation submitted by Stellaria is therefore now under review.
The Stellarium runs smoothly and quietly, even in harsh conditions. This is thanks to the use of molten salts as fuel.
With four containment barriers and an underground installation, the Stellarium is the safest reactor on the market under all circumstances.
Stellaria’s application highlights issues related to the safety case, including a detailed description of the installation, the safety principles adopted, the analysis of incidents and accidents, including severe accidents, the management of external hazards (earthquakes, flooding, aircraft crashes), as well as radiation protection for workers, the public, and the environment.
The company also provided details related to reactor’s environmental impact assessment and the conditions planned for decommissioning the installation at the end of its lifetime.
Molten salt reactors (MSRs) use molten fluoride salts as primary coolant, at low pressure. They may operate with epithermal or fast neutron spectrums, and with a variety of fuels. Much of the interest today in reviving the MSR concept relates to using thorium (to breed fissile uranium-233), where an initial source of fissile material such as plutonium-239 needs to be provided. There are a number of different MSR design concepts, and a number of interesting challenges in the commercialisation of many, especially with thorium, reported World Nuclear News.