At unit 7 of Russia’s Leningrad NPP (also known as Leningrad-II unit 3) reinforcement and concreting of the annular corridor of the reactor building has been completed. This structure is extremely important as elements of the prestressing system of the internal containment will be placed in the corridor. This is a passive, localising power unit security system. Its main task is to ensure the integrity and strength of the internal containment shell of the reactor building and to guarantee its tightness during operation.
Finishing the annular corridor paves the way for installation of the lower and subsequent tiers of the internal containment shell and their subsequent concreting. It is planned that this work will begin in September and will last for two and a half years.
“We will have to create a reinforced concrete structure with a thickness of more than a metre, reinforced with steel ropes for strength,” said Evgeny Milushkin, Deputy Director for Capital Construction and Head of the Leningrad-II Capital Construction Department. “These will be installed in vertical and horizontal channels, stretched with jacks. They will hold the containment shell in the form of a grid and make it reliable and durable, capable of withstanding significant loads in any operating conditions. The inner containment will also prevent radioactive substances and ionising radiation from leaving the reactor building. This means that the personnel of the nuclear power plant, the population living next to it and the environment will be safe,”
The first tier of the inner containment will be ready for installation soon. The specialists of the general contractor company carry out the large-scale assembly and welding of its elements on a special slipway next to the reactor building. to date, 22 of the 24 structural elements have been assembled and welded.
The complete inner protective shell of the reactor building, including the cylindrical part and the dome, will be ready in 2028. At the same time, the builders will erect the outer protective shell. The latter will protect the reactor, steam generators and other important equipment from extreme external natural and man-made impacts such as hurricanes, explosions, earthquakes, shock waves, plane crashes, etc.
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.
