Russia successfully advances preparatory work on Leningrad 8 nuclear unit

Preparatory work on a new VVER-1200 nuclear unit at Russia’s Leningrad nuclear power plant is progressing successfully. Technicians completed excavation of the foundation pit more than two months ahead of schedule and plan to officially begin construction in the first half of next year. The second of the plant’s two new units is currently scheduled to enter commercial operation in 2032.

Russia’s Rosenergoatom announced that it had successfully completed another preparatory milestone for the construction of the new Leningrad 8 nuclear unit (also known as Leningrad II-4). In early August, technicians completed excavation of the foundation pit for the reactor building of the VVER-1200 unit two and a half months ahead of schedule.

“The foundation pit construction technology involved installing a multilayer drainage system—lean concrete, sand and cellular concrete. We used B35-grade concrete, which is considered a heavy material with high density and is used for monolithic structures exposed to significant loads,” said Konstantin Khudyakov of TITAN-2, the company responsible for the work.

The next steps in the preparatory phase include lightning protection and waterproofing. In October, construction workers will begin preparing the foundation slab reinforcement. Concreting the slab in the first half of the year will officially mark the start of construction of the unit. Rosenergoatom had originally planned to officially begin work in May 2025, but the preparatory work is ahead of schedule, so it may begin somewhat earlier.

As part of the official construction phase, a 70-metre-high reactor building will rise from the foundation slab within five years.

Replacing the “Chernobyl” reactors

With a capacity of 4400 MW, the Leningrad nuclear power plant is currently Russia’s largest. Its first phase had four RBMK-1000 reactors dating from the 1970s and 1980s, the same type as those at the infamous Chernobyl nuclear power plant. Russia shut down the first two in 2018 and 2020. The other two RBMK units are scheduled to reach the end of their service lives in 2025 and 2026.

As part of the second phase, Russia commissioned two VVER-1200 units in 2018 and 2021. Official construction of Unit 7 (Leningrad II-3) began in March this year. The second pair of VVER-1200 units is scheduled to enter commercial operation in 2030 and 2032. Russia aims to increase the share of electricity generated by nuclear power from 20 % to 25 % over the next 20 years.