On December 19, 2025, 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. Stellaria is the first French start-up working on fast-neutron reactors to submit such an application.
The application concerns the siting and construction of its Alvin prototype, scheduled to start up in 2030, in order to launch the test program that will definitively validate the concept. This new milestone represents a crucial step in the development of the French company and in the implementation of its Stellarium reactor reactor, as it sets out the main principles of the project and officially elevates the start-up to the status of a nuclear operator.
A first step towards the prototype
"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. 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", says Nicolas Breyton, President of Stellaria.
This Application for Authorization to Create a Basic Nuclear Installation (INB) comprises around fifteen documents totaling more than one thousand pages. Prepared by Stellaria’s teams, it notably includes:
- 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 environmental impact assessment of the installation;
- The conditions planned for decommissioning the installation at the end of its lifetime;
- A presentation of the operator’s technical and financial capabilities;
- All technical documents describing the installation in depth, which are essential for the review of the application.
What is the next step after submitting the application?
The Application for Authorization to Create a Basic Nuclear Installation submitted by Stellaria is therefore now under review. To date, Stellaria is the first company to have filed such an application with the authorities in the French fast-neutron nuclear market, and the second among the eleven French start-ups working on the development of SMRs or AMRs, after Jimmy Energy.
