Construction work has begun on the outer protective shell for the seventh unit of the Leningrad Nuclear Power Plant.

Rosatom has begun the construction of the external protective shell (outer containment building) for the third new unit at the Leningrad Nuclear Power Plant, which will be the seventh in total at that site.

This phase of the works is a key part of the construction of the new reactors, known as Leningrad II, which will replace the older units from the 1970s.

The current phase of the Leningrad Nuclear Power Plant II already includes two VVER-1200 reactors (pressurized water reactors) that were commissioned in 2018 and 2021, and units 7 and 8 (or Leningrad II-3 and II-4) are under construction and they will gradually replace the four original RBMK-1000 reactors.

The outer protective shell is part of the double protection system of the VVER-1200 reactor. While the inner containment provides primary protection, the outer is designed to provide additional safety from external threats, such as earthquakes and aircraft impacts. Reactors of this type are also equipped with a core catcher whose task is to contain molten material in a subcritical geometric form, thereby stopping the chain fission reaction. 

The works involve progressively installing reinforced concrete layers which will then be filled with concrete. Upon completion, the external shell will be 70 meters high, 52 meters in diameter, and 80 centimeters thick.

Evgeny Milushkin from Leningrad NE-2 stated that the plan is to complete the first level, about four meters high, already in November, which will require over 200 tons of steel reinforcement and nearly 600 cubic meters of concrete. The complete external protective structure will be ready in 2028. At the same time, work is also underway on the internal protective shell, as well as on the reactor building and the core catcher (core catcher).

By the way, the Leningrad Nuclear Power Plant is one of the largest in Russia, with an installed capacity of 4,400 megawatts, and provides more than 55% of the electricity demand in Saint Petersburg and Leningrad Oblast. The first two RBMK-1000 units (Leningrad 1 and 2) have already been permanently shut down. Units 7 and 8 will replace units 3 and 4 as they are gradually closed in the coming years.

The main construction phase of Unit 7 began in March 2024, and it is planned that the new units will enter commercial operation in 2030 and 2032, providing electricity with a designed operating life of 60 years, with the possibility of extension for an additional 20 years.

Sources: World Nuclear News