ATRIUM: an innovative sodium-cooled advanced modular reactor concept
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In the French national energy & climate plan (PPE), the long-term strategy to close the fuel cycle is expected to be based on fast reactors, which is why conceptual design studies are conducted in this field.​​​

Cœur de l’AMR-Na ATRIUM - carré © IRESNE/CEA

The IRESNE teams at the Reactor Studies Department (DER) have come up with an innovative technical concept that focuses on inherent safety characteristics, i.e. ATRIUM, which is a low-power sodium-cooled fast reactor.

The first of the innovations is its core - dubbed CADOR - that exploits the effects of a stronger Doppler counter-reaction. This novel core takes into account two significant changes with respect to more conventional concepts:

  • It uses a “cold” fuel during operation, i.e. the mean fuel temperature is lower by about 400°C compared with the fuel used in the Phenix reactor.

  • The neutron spectrum is slightly moderated thanks to the addition of beryllium pins in all the fuel assemblies.

The second innovation lies in its completely passive decay heat removal system (DHRS).