Rosenergoatom, the nuclear power plant operating division of Russian state nuclear corporation Rosatom - said that construction of the pit lasted for about two months and was completed two-and-a-half months ahead of schedule.
The work was carried out by workers from Titan-2, the general contractor for the construction of new power units of the Leningrad plant.
In June of this year, the construction of the foundation pit for the reactor building of unit 8 was completed. This work was completed two weeks ahead of schedule.
"The technology for constructing the concrete foundation pit included the implementation of a multi-layer drainage system - lean concrete, sand, porous concrete," said Konstantin Khudyakov, director of the Leningrad NPP Facilities Programme of JSC Concern Titan-2. "Then the drainage system was cut off with a special membrane before the concrete preparation itself."
The next stage is the start of lightning protection and waterproofing work, which will last until the end of August. Then the screed will be installed.
Evgeny Milushkin, deputy director for capital construction and head of the capital construction department of the Leningrad II plant, added: "The completed work will allow specialists to start reinforcing the foundation slab. Reinforcement with steel reinforcement creates a kind of framework and makes the foundation extremely strong. The reinforcement work is defined by an additional schedule and will begin in October of this year. Thus, we are preparing for the first key operation - concreting the foundation slab of the reactor building."
The Leningrad plant is one of the largest in Russia, with an installed capacity of 4400 MWe, and provides more than 55% of the electricity demand of St Petersburg and the Leningrad region, or 30% of all the electricity in northwest Russia.
Leningrad units 1 and 2 - both 1000 MWe RBMK units - shut down in 2018 and 2020, respectively. As the first two of the plant's four RBMK-1000 units shut down, new VVER-1200 units started at the neighbouring Leningrad II plant. The 60-year service life of these fifth and sixth units (also known as Leningrad II-1 and Leningrad II-2) secures power supply until the 2080s. Units 7 and 8 will replace units 3 and 4 as they are shut in the coming years.
The pouring of the first concrete for unit 7 in March this year marked the start of the main phase of construction of the new power unit, which is expected to generate power for 60 years, with the possibility of a 20-year extension. The foundation slab consists of about 5500 cubic metres of concrete. Last month, Rosatom said the work on the reactor building is currently running two-and-a-half months ahead of schedule, with concreting of the foundation completed.
Leningrad units 7 and 8 (or Leningrad II-3 and Leningrad II-4) are planned to be commissioned in 2030 and 2032, respectively.
