Rosatom finishes Kursk II Unit 3 foundation slab ahead of schedule

Rosatom has cleared a key civil-works gate at Kursk II: the Unit 3 foundation slab was completed ahead of schedule, opening the way for the next structural phase of the new-build. About 200 workers spent four months pouring the 5,400-square-metre slab, with multi-level quality control tracking dozens of parameters as the concrete went in.

That matters because a completed foundation is not just a box to tick. In a reactor project, the slab fixes the geometry and load path for the whole unit. Once it is in place, crews can move into reinforced-concrete blocks, then the main walls of the power unit building, and then the internal containment shell. In practical terms, the site has moved from heavy earthworks and base construction into the part of the job where the reactor building starts to rise in a recognizable form.

The real credibility test is whether “ahead of schedule” at this stage translates into the same discipline later, or whether it becomes the kind of milestone that looks better on a construction chart than it does in the final commissioning timeline. Nuclear projects often make clean progress through early civil works and then slow down when major equipment, systems installation and test programs take over. Kursk II already gives Rosatom a useful reference point: the first new unit was connected to the grid on December 31, 2025, reached full power on March 16, 2026, and was ready for commercial operation on April 21, 2026.

Kursk II is designed for four VVER-TOI reactors rated at 1,250 MWe each, and those units are meant to replace the four RBMK-1000 reactors at the nearby Kursk Nuclear Power Plant. The first RBMK unit was shut down in December 2021 after 45 years of operation, and the second followed in January 2024. The remaining original units are scheduled to shut by 2031, while Rosatom’s long-range target is to bring all four Kursk II units into operation by 2034.

The project is unfolding under wartime pressure and sanctions-era constraints. In August 2024, International Atomic Energy Agency Director General Rafael Grossi said he was personally leading an IAEA mission to Kursk because of the serious situation and increased military activity nearby, and the agency has warned about nuclear safety and security risks at the site in the context of the conflict. Even so, the IAEA’s PRIS database still lists Kursk II as under construction, which makes each visible civil milestone a concrete check on whether Rosatom can keep the program moving.

For now, the Unit 3 slab says something simple and useful to the industry: Rosatom is still delivering major reactor concrete on time or better, and the next test is whether that pace survives the harder work ahead.