Rosatom manufactures unique Gen IV nuclear fuel

Rosatom’s Fuel Division has manufactured and accepted the unique fuel assembly ОС-5 based on nitride uranium-plutonium (SNUP) fuel with a liquid-metal sublayer (metallic sodium) placed under the steel cladding.

• Main action: The Fuel Division produced and accepted the OS-5 fuel assembly that for the first time uses a metallic sodium sublayer under the steel cladding which “envelopes” the uranium-plutonium fuel pellets, intended to improve SNUP fuel performance for Generation IV fast-neutron reactors (expected effects: lower fuel temperature, reduced pellet swelling, and reduced cladding stress). The article date is 2025-09-16.
• Program context and background: OS-5 is part of a larger program to increase SNUP fuel efficiency for the BREST-OD-300 innovative fast reactor under construction in Seversk, Tomsk Oblast, within the strategic industry project “Proryv” (Breakthrough); Rosatom scientists have conducted experimental-industrial operation of SNUP fuel since 2014 in the BN-600 reactor at Beloyarsk NPP, including post-irradiation examinations that support progressively higher burnup.