A major milestone has been achieved at Unit 6 of the Novovoronezh Nuclear Power Plant (NPP) in Russia, where a batch of fifth-generation nuclear fuel assemblies, known as TVS-5, has been loaded into the VVER-1200 reactor core for the first time. The loading took place during a scheduled maintenance shutdown and marks the beginning of pilot operations that will span three 18-month fuel cycles.

Manufactured by the Novosibirsk Chemical Concentrates Plant, part of Rosatom's Fuel Division, the new fuel bundles are designed for fully automated fabrication — a critical step towards scaling up the industrial production of uranium-plutonium fuel for VVER reactors. This advancement supports Russia’s broader strategy of transitioning to a dual-component nuclear power system that integrates both thermal and fast neutron reactors, and implements a closed nuclear fuel cycle.

Alexander Ugryumov, Senior Vice President for R&D at TVEL, the head company of Rosatom’s Fuel Division, highlighted the significance of the development: “The use of regenerated nuclear materials in thermal reactors is essential for closing the nuclear fuel cycle. Industrial-scale automated production is required, similar to fast reactor fuel manufacturing. TVS-5 at Novovoronezh is a critical step toward validating this process.”

The pilot phase will use the new TVS-5 bundles with a conventional uranium dioxide matrix enriched with uranium. The project is being conducted under the regulatory supervision of Rostechnadzor, the Russian national nuclear authority.

Vladimir Povarov, Director of Novovoronezh NPP, said: “Loading this fifth-generation fuel confirms our role as a hub for advanced nuclear technologies. This step is crucial in closing the fuel cycle and supports Rosatom’s strategic initiatives, contributing to the future of Russia’s nuclear power sector.”

The VVER series of thermal light-water reactors form the backbone of Russia’s nuclear fleet and are also widely deployed in nuclear power stations abroad that are built to Russian design specifications.

Russia’s long-term nuclear development roadmap centres around a dual-component model. This includes using fast reactors to convert spent fuel into fresh uranium-plutonium fuel, closing the loop on the nuclear fuel cycle. As fast reactors are deployed more broadly, a balanced and sustainable circulation of nuclear materials between fast and thermal reactors is expected. The introduction of TVS-5 is seen as a key technical and strategic enabler of this closed-cycle approach.