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The CEA presents two nuclear startups, Hexana and Stellaria

​The CEA recently introduced its new nuclear startups at the Global Summit - Hello Tomorrow: Hexana and Stellaria. These two startups benefit from the CEA’s technologies and patents to develop the fourth generation of small advanced modular reactors (AMR). Through the France 2030 programme, the CEA is committed to supporting startups looking to promote decarbonisation through the development of innovative reactor projects.

Published on 17 March 2023


Hexana intends to develop an AMR based on the sodium-cooled fast reactor technology that incorporates a high-temperature storage device.

This facility will comprise two small reactor units (400 MWth each) that will supply a heat storage device specially designed to manage the industry’s fluctuating demand for electric power. It will be equipped with an energy conversion system to ensure the flexible production of electricity on demand, making it possible to compete with gas-fired power stations and provide process heat directly to energy-intensive industries within close proximity. With both electricity and process heat, the latter will be able to capture CO2, to produce steam, hydrogen and synthetic fuels, and to commit firmly to their decarbonisation process.


Paul Gauthé, Jean-Baptiste Droin, Sylvain Nizou © CEA/L.Godart

Sodium-cooled fast reactors are of great interest with respect to nuclear waste management: they do not need natural or enriched uranium fuels to operate, but rather use depleted uranium combined with recycled plutonium collected from the reprocessing of French spent fuels (MOX). These reactors can thus help consolidate France’s energy sovereignty and reduce its volume of high-level nuclear waste within the scope of closing the nuclear fuel cycle.


Stellaria is looking to develop an energy system based on the molten chloride fast reactor (MCFR) technology.

Guillaume Campioni, Lucas Tardieu, Nicolas Breyton © CEA/L.Godart

In this type of reactor, the fuel is diluted in the molten salt, which also acts as the coolant. The reactor can operate without stopping for refuelling because the liquid fuel can be extracted and recycled continuously. The main advantage of this new reactor technology lies in the fact that it combines power generation, the multiple recycling of fuel, and passive safety features by design (natural convection, no pressure, self-stabilising core).
The reactor developed by Stellaria will be extremely compact i.e. 250 MWth in 4 m3. Like Hexana, it will also be capable of operating with various types of nuclear fuels (uranium, plutonium, MOX, minor actinides and even thorium), reflecting France’s determined strategy to close the nuclear fuel cycle.

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