Reinforcement and concreting of the annular corridor for the reactor building of unit 8 (also known as Leningrad-II unit 4) at Russia’s Leningrad NPP has been completed. This is one of the elements of the prestressing system of internal containment shell. Almost 1,500 tonnes of reinforcement and more than 3,000 cubic metres of concrete was used for the task which took several months of work.
“The ring corridor is the basis on which it is now possible to build the internal containment of the reactor building in tiers. It is a powerful reinforced concrete structure more than one meter thick,” said Evgeny Milushkin, Deputy Director of the Leningrad NPP and Head of the Capital Construction Department of the Leningrad-II NPP. “During operation of the power unit, it will prevent the release of radioactive substances and ionising radiation outside the reactor building and ensure the safety of nuclear power plant personnel living near the nuclear power plant and the environment.”
He added: “To give the containment strength we will prestress it using horizontal and vertical steel ropes which will squeeze it from all sides. This way, the containment is guaranteed to be able to withstand the highest possible internal long-term loads in any operating mode.”
The first tier of the internal containment is planned to be installed in in the near future, almost a month ahead of schedule. Its steel elements have already been assembled and welded together. The quality of manufacturing of the building structure has been confirmed. Now the tier is awaiting its launch on the slipway next to the reactor building.
“By the end of the year, our specialists will manufacture and install two more similar structures to bring the internal containment to more than 14,400 metres, almost a quarter of the design height,” said Konstantin Khudyakov, Director of the programme for Leningrad NPP facilities at general contractor Titan-2. “In addition to the internal containment, we will also build an external containment made of reinforcement and special concrete with a thickness of 800 to 600 millimetres. This will protect the reactor plant from extreme natural and external man-made impacts.”
The double containment, including the cylindrical part and the dome, will be ready in 2030. By then, all internal building structures of the reactor building will be completed and its main equipment, including the nuclear reactor, will be installed. This installation will take three years. The double containment is a distinctive feature of the Russian power units with VVER-1200 reactors.
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 the RBMK-1000 reactors at units 1&2, which were decommissioned in 2018 and 2020. New VVER-1200 units (7&8), now under construction, will replace units 3&4. Unit 7 is scheduled to begin operation in 2030 and unit 8 in 2032.
