European SMR Development: From Vision to Decision with Stellaria's Molten Salt Reactor Progress
European discussions around Small Modular Reactors are transitioning from theoretical studies to concrete strategic choices for energy sovereignty. Stellaria, a French innovator, is advancing its fast neutron molten salt reactor technology, demonstrating tangible progress through design finalizations, regulatory filings, and significant funding. This shift highlights a potential new phase for advanced nuclear energy in the European energy mix.
24 June 2026
Stellaria, established in June 2023, is actively developing fast neutron molten salt reactors with a focus on closing the fuel cycle, reducing highly radioactive waste, and decreasing radiotoxicity. The company has finalized Summary Preliminary Designs for its Stellarium series unit, the ALVIN critical experiment (100 kW planned for 2029), and the MEGALVIN prototype (10 MW planned for 2030). Significant milestones include filing the Demande d’Autorisation de Création for ALVIN with French authorities in December 2025, securing €10 million from France 2030 and €23 million in a 2025 funding round, and a pre-order agreement with Equinix for 500 MWe for data centers.
The ongoing development of advanced nuclear technologies like Stellaria's molten salt reactor reflects a broader movement within the energy sector to explore diverse generation options beyond conventional designs. With intrinsic safety features such as no pressure operation, inert gas use, and underground installation, MSRs represent a distinct approach to nuclear power generation, emphasizing passive safety and waste reduction. As Europe increasingly considers nuclear energy alongside renewables for its energy sovereignty, the tangible progress of companies like Stellaria contributes to a wider understanding of the technological possibilities and challenges.
The trajectory of Stellaria's ALVIN and MEGALVIN prototypes towards their planned deployments in 2029 and 2030 will be key indicators of progress for this specific MSR technology. The potential for 'Stellarium' series units to be deployed from 2035, especially for industrial applications like data centers as seen with the Equinix agreement, suggests a pragmatic path for early adoption. Observing the regulatory processes with the French Nuclear Safety Authority and the outcomes of collaborations with institutions like CEA, JRC, TU Delft, and SCK CEN will be crucial in understanding the future role of such advanced reactors in the European energy landscape.
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This article was drafted with AI assistance and editorially reviewed.