Russia's liquid metal nuclear fuel assembly to advance fast reactors

Russia’s state nuclear corporation Rosatom has developed and accepted a new nuclear fuel assembly, OS-5, designed for use in fourth-generation fast neutron reactors, specifically the BREST-OD-300 reactor. This assembly features mixed nitride uranium-plutonium (SNUPP) fuel with a novel liquid metal sublayer intended to lower fuel operating temperatures without altering coolant parameters. This design aims to reduce thermal expansion of the fuel pellets, thereby minimizing mechanical stress on the cladding and improving fuel reliability and economic efficiency. The BREST-OD-300, a 300 MWe fast neutron reactor, is central to Rosatom’s “Proryv” (Breakthrough) project, which seeks to establish a closed nuclear fuel cycle by reprocessing used fuel to recover plutonium and actinides for new fuel fabrication, thus reducing nuclear waste volume and radiotoxicity. The OS-5 fuel assembly is slated for pilot industrial operation in the BN-600 reactor at the Beloyarsk nuclear power