The construction of a ring foundation for an evaporative cooling tower has begun at the construction site of unit 7 of the Leningrad NPP (also known as Leningrad-II unit 3) After completion, the cooling tower will become the tallest building in the Leningrad region and the second tallest building in St Petersburg after the Lakhta Centre skyscraper.
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) will replace units 3&4. First concrete for unit 7 also took place ahead of schedule.
Currently, builders are reinforcing the base for the unit 7 cooling tower shell. In total, they will need about 1,500 tonnes of reinforcement with a diameter of 8-40 millimetres and almost 5.500 cubic metres of concrete to build the foundation. This will be prepared at a concrete plant in the immediate vicinity of the site of the new unit allowing rapid delivery of the finished mixture to the cooling tower.
Specialists will use Portland cement to prepare the concrete. Concrete mixtures made of this material are highly waterproof, frost–resistant and durable and are used in the construction of particularly important and complex facilities such as subways, dams and bridges.
“High-grade concrete, coupled with a rigid reinforced frame, as well as a pre-made base of 760 drilling piles, will be a reliable support for the 179-metre-high cooling tower and the equipment placed inside it,” said Evgeny Milushkin, Deputy Director for Capital Construction and Head of the Capital Construction Department of Leningrad-II NPP. “In addition to the ring foundation for the tower, this year will see construction of separate foundations for each of the 50 pillars of the reinforced concrete inclined colonnade of the cooling tower and the foundation and walls for its drainage basin.”
The builders will begin construction of the cooling tower itself next year. A tower crane will be installed inside the future cooling tower to concrete the shell, and a self-lifting sliding formwork will be used during the work. The latter will make it possible to work without disassembling the structure and installing it in a new location, which greatly optimises the concreting process. The use of such a formwork will also affect the quality of the work. Because of the continuous pouring of the concrete mixture, the exhaust tower will be monolithic, increasing its the overall strength.
Currently, Leningrad-II operates two tower evaporative cooling towers – one with a height of 150 metre for unit 1 (Leningrad unit 5) and one with a height of 167 metres for unit 2 (Leningrad 6).
