Russia's BREST-OD-300 reactor hits major build milestone with lead coolant system

Russia's BREST-OD-300 fast reactor has reached a key construction milestone. Workers have installed the final shell of the peripheral cavity at the Seversk site. The reactor forms the centrepiece of Rosatom's Proryv project, which aims to create a closed nuclear fuel cycle.

The BREST-OD-300 is a 300 MWe demonstration unit being built at the Siberian Chemical Combine. Its design features an integral layout with a metal-concrete vessel structure. The central cladding will house the core basket and fuel assemblies, while the surrounding cavities form part of the lead coolant system.

Assembly of the reactor's pressure vessel is now around 70% complete. By the end of 2026, crews will finish the vessel's concrete work and install all major internal components. The next phase involves linking the peripheral cavities to the central cladding, creating a closed loop for the lead coolant.

Once operational, the reactor will initially focus on performance testing. Commercial use is expected to begin after roughly a decade of trials.

The project remains on track for vessel completion by late 2026. After that, the lead coolant circuit will be finalised, and internal systems will be installed. The reactor's long-term goal is to demonstrate a sustainable closed fuel cycle for nuclear power.