Smolensk Nuclear Power Plant Begins Loading Improved Nuclear Fuel
Smolensk Nuclear Power Plant has begun the phased loading of fuel assemblies with an improved fuel composition into Unit 1.
The new fuel compensates for changes in key core parameters following repairs to the reactor’s graphite stack.
Optimizing the Fuel Composition
Smolensk Nuclear Power Plant has used uranium-erbium fuel since the mid-2000s. In standard fuel assemblies, uranium-235 enrichment is 2.8%, while the mass fraction of erbium oxide is 0.6%. Erbium acts as a burnable neutron absorber. Restoring the graphite required adjustments to core parameters to improve safety and extend the reactor’s operating life.
Research showed that optimizing the fuel composition was essential. The work was carried out by the Research and Development Institute of Power Engineering (NIKIET), the Kurchatov Institute and the Russian Research Institute for Nuclear Power Plant Operation. In the new fuel assemblies, uranium-235 enrichment has been reduced to 2.7%, while the erbium content has been lowered to 0.35%.
Digital Modeling and Safety
Before loading the new assemblies, engineers analyzed all operating modes of the reactor system and provided a safety case covering nuclear and radiation safety.
Specialized software played a major role. Using these tools, engineers modeled key processes with the new fuel type. The work demonstrates the practical use of specialized Russian software for mathematical modeling of complex nuclear facilities. In nuclear power, such software is effectively part of the plant’s technological control system.
The calculations showed that the optimized fuel meets all requirements for safe nuclear power plant operation. Based on the modeling results, plant management made the necessary changes to the operating license conditions for Unit 1.
An Operating-Life Extension Strategy
Initially, a batch of 200 fuel assemblies will be loaded into the reactor core. The assemblies were manufactured at the Machine-Building Plant in Elektrostal, part of Rosatom’s Fuel Division. Engineers will closely monitor the performance of this test batch. In the future, the optimized assemblies are planned for use in all three units at Smolensk Nuclear Power Plant.
Introducing the improved fuel will significantly extend the service life of RBMK-1000 reactors. The new fuel assemblies are expected to allow the units to operate for up to 50 years.
Modernizing existing nuclear power plants also addresses a broader economic objective. Preserving and improving the efficiency of existing generating capacity will help increase nuclear power’s share of Russia’s energy mix from about 20% to 25% by 2045. Russian President Vladimir Putin recently set this target for the government and the State Atomic Energy Corporation Rosatom.
Export Potential and the Outlook
For now, the expertise accumulated at Smolensk Nuclear Power Plant has mainly indirect export potential, but that could change over time. Rosatom is already transferring its experience with uranium-erbium fuel to water-cooled, water-moderated power reactors (VVERs). Reactor testing of uranium-erbium fuel for VVERs began in December 2024, and more such applications are expected in the future.
That means Russia could soon export not just an individual fuel assembly, but a broader package of capabilities: fuel engineering, computational software, licensing and operational support. This approach is already being used for VVERs abroad. For example, when supplying fuel to India’s Kudankulam Nuclear Power Plant, Rosatom is simultaneously introducing advanced fuel assemblies and longer fuel cycles.
