Concreting of outer dome completed at unit 1 of Kursk-II NPP

30 August 2023

The outer containment (NZO) at unit 1 of Russia’s Kursk-II NPP has been concreted. The process of erecting the NZO dome takes place in several stages: the manufacture of the constituent elements of each of the six tiers; then their installation; and phased concreting. The containment has a height of 65.4 metres, a diameter of 26.9 metres and a wall thickness of 1,500 millimetres. The construction work was completed in 206 days during which 4,000 cubic metres of concrete were used.

The NZO is a is a reinforced concrete structure that protect the reactor plant from extreme external influences. In addition to the NZO, there is an internal containment that provides protection for personnel, the public and the environment. Its construction was completed in October 2022. Double containment is a feature of the VVER-1200 and VVER-TOI reactors.

“Concreting of the NZO dome is the final stage in the construction of one of the physical barriers of the nuclear power plant's defence in depth,” said Andrey Osharin, First Deputy Director for the Construction of New Units. “We used self-compacting concrete, capable of spreading under gravity, filling the mould and achieving full compaction even in heavily reinforced structures. The mixture enables fast laying, speeds up construction time and is evenly distributed in the reinforced concrete structure.” The concrete’s fluidity and resistance to delamination provide a high degree of uniformity, minimal voiding, and ensures high-quality surfaces and durability. The concrete used has a low water-cement ratio,

Specialists from Trest RosSEM controlled the quality of the concrete mixture throughout the entire period of concreting. Next, the contractors will proceed with the installation of the deflector and air ducts of the passive heat removal system (PHRS).

Meanwhile, construction of the unit 2 cooling tower has been completed. It took specialists two years and one month to build the tower. Kursk-II NPP now boasts the two tallest cooling towers in Russia each 179 metres high. The design life of the cooling towers is up to 100 years. Now the builders are faced with the task of installing prefabricated reinforced concrete inside the cooling tower for mounting blocks of irrigation facilities, as well as water outlets and supply pipelines.

Kursk II is intended as a replacement station for the currently operating Kursk NPP, which comprises four ageing RBMK reactors (one of which is already closed). Units 1&2, currently under construction, are being built according to the VVER-TOI project (standard optimised informatised pressurised water power reactor), which is a development of the VVER-1200 reactor design. Public discussions began in February on the siting of units 3&4. Currently work is being carried out at 156 facilities on the Kursk-II site. The number of construction and installation personnel in August 2023 amounted to more than 8,500.

Image courtesy of Rosatom

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