Russia's Smolensk Unit 1 Retrofitted with Improved Fuel to Extend Service Life to 50 Years

en.Wedoany.com Reported - On September 1, Smolensk Nuclear Power Plant, a subsidiary of Rosatom, began the phased loading of optimized uranium-erbium nuclear fuel assemblies into Unit 1. The unit operates an RBMK-1000 reactor, and the new fuel adjusts the uranium-235 enrichment from 2.8% in the current fuel to 2.7%, while reducing the erbium oxide content from 0.6% to 0.35%. The initial batch is planned to include 200 fuel assemblies.

Smolensk Nuclear Power Plant has been using uranium-erbium fuel since the mid-2000s, with erbium oxide serving as a burnable neutron absorber material. This change in fuel composition is directly related to the management of the graphite stack resource characteristics of Unit 1. The unit entered scheduled major maintenance on May 9, 2026, and was restored to 100% power on July 23; during the maintenance period, the fourth phase of graphite stack resource management operations was completed, restoring the resources of 195 process channel units and replacing 26 control and protection system channels.

The parameters of the new fuel were determined following separate computational studies conducted by the Research and Development Institute of Power Engineering (NIKIET), the Kurchatov Research Center, and the All-Russian Research Institute for Nuclear Power Plant Operation. The studies focused on changes in the neutron-physical characteristics of the core after graphite structure repairs, and calculations were performed for various combinations of uranium-235 enrichment and erbium content, with the combination of 2.7% uranium-235 and 0.35% erbium content selected for subsequent loading. Research materials previously published by NIKIET indicate that the initial batch of 200 fuel assemblies with this composition can be used to verify changes in the neutron-physical characteristics of the RBMK-1000 after graphite core repairs.

Prior to fuel loading, Smolensk Nuclear Power Plant completed analyses of various reactor operating conditions, prepared documentation substantiating nuclear and radiation safety during the use of the new fuel, and completed relevant software certification and bench testing. Corresponding changes have also been made to the operating license conditions for Unit 1. Plant calculations show that the adjusted fuel parameters can compensate for some of the changes in core neutron-physical characteristics resulting from graphite structure repairs, while maintaining parameters related to reactor control and self-protection.

This batch of optimized fuel was produced by the Machine-Building Plant in Elektrostal, part of Rosatom's fuel division. Smolensk Nuclear Power Plant will track the operational data of the initial 200 fuel assemblies, and the results of the analysis will be used to substantiate the conditions for expanding the loading of this fuel type across all units at the plant, as well as to provide the technical basis for extending the service life of RBMK-1000 units to 50 years.

Smolensk Nuclear Power Plant currently operates three RBMK-1000 units, each with an electrical output of 1,000 MW. Unit 1 was commissioned in 1982 and is currently undergoing life-extension-related technical work, including graphite stack resource management, equipment maintenance, and fuel optimization. The loading of these 200 fuel assemblies constitutes the initial operational validation phase, and whether full-scale loading across all three units will follow will be determined based on the results of the actual operational analysis of the initial fuel batch.