Workers have begun construction of the outer containment (NZO – Naruzhnoi Zashitnoi Obolochki) at unit 7 of Russia’s Leningrad NPP (also known as Leningrad-II unit 3). The containment will protect the reactor, steam generators and other important equipment from external influences. Builders will sequentially erect several tiers of reinforced frame and fill them with special concrete to create a powerful structure more than 70 metres high, almost 52 metres in diameter and 800 millimetres thick. The containment is capable of withstanding hurricanes, shock waves, earthquakes and external explosions as well as the fall of aircraft.
“The construction of the outer protective shell will be carried out in tiers. We plan that the first one will be ready in November, explained Evgeny Milushkin, Deputy Director for Capital Construction and Head of the Capital Construction Department of at Leningrad-II. “To construct a structure about four metres high, more than 200 Tonnes of steel reinforcement and almost 600 cubic metres of concrete mixture will be required. By the beginning of next year, the shell will grow by another four metres. The containment will be completed in 2028.”
In parallel with the NZO, builders are erecting the inner containment (Vnutrennei Zashitnoi Obolochki). During operation, it will prevent the release of radioactive substances and ionising radiation into the environment. The two containment shells of the reactor building will ensure the highest level of safety. Other work is also underway at unit 7 including installation of the melt trap and erection of internal building structures and laying the foundation for the turbine building.
Currently, about 1,000 people are involved in the construction of units 7&8 at Leningrad NPP. Construction and installation work is being carried out at 25 sites. In the future, as new facilities are opened, the number of workers will increase. In the coming years, they will have to build about 150 buildings and structures, fill them with equipment, set up and test technological and security systems, lay heating networks, power supply networks, water distribution, sewerage, roads and pedestrian roads, carry out landscaping ready for commissioning of the units in 2030 and 2032.
Currently Leningrad NPP has four units in operation – units 3&4 with Soviet RBMK-1000 reactors, as well units 5&6 with new VVER-1200 units (also known as Leningrad-II 1&2). Units 5&6 replaced units 1&2 with RBMK-1000 reactors, which were decommissioned in 2018 and 2020. New VVER-1200 units (7&8), now under construction, will replace units 3&4.
