Leningrad 7 assembly starts

A complete set of equipment for the lower tier of the internal containment (VZO – Vnutrennei Zatsitnoi Obolochk) for the unit 7 reactor building (also known as Leningrad-II unit 3) at the Leningrad NPP has been manufactured and passed the mandatory incoming control procedure. It is now being transported to the construction site.

In the next two months, specialists will carry out enlarged assembly and welding of 24 metal sections (grades) and install the resulting building structure on the reactor building. This will launch the creation of one of the most important passive safety systems of the power unit.

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.

We will assemble the segments together like a ship’s hull – on a special slipway, said Evgeniy Milushkin, Deputy Director for Capital Construction and Head of the Capital Construction Department at Leningrad-II. “Its metal structures, 12 metres high and 44 metres in diameter, have already been installed in the immediate vicinity of the power unit. This method has proven itself well when carrying out similar work at the first stage of VVER-1200 and is today successfully replicated at Russian and foreign nuclear construction sites. It makes it possible to avoid conducting operations at altitude. This means that the work will be carried out without unnecessary labour costs, with high quality and, importantly, safely for the staff. At the same time, we will supplement metal structures with pressurised penetrations and other elements.”

To install the enlarged metal structures on the reactor building, a special multi-vector traverse and a heavy crawler crane will be needed. The traverse will be manufactured and tested, and the crane will be assembled and tested by the end of August this year. After this, specialists will install the first tier of the VZO on the reactor building. This key operation is scheduled for September 2025.

At the next stages, the remaining tiers of the cylindrical and dome parts of the internal protective shell will be manufactured, mounted, installed and concreted. The VZO is one of the localising safety systems ensuring the internal tightness of the reactor building in all operating modes.

Meanwhile, a meeting of the operational headquarters was held to discuss the construction of units 7&8. The director of the enterprise, Vladimir Pereguda, noted the tasks set by the leadership of the nuclear industry to the team of participants in the project for the construction of a new stage of the Leningrad NPP for the first six months of this year have been completed, many of them ahead of schedule. Construction and installation work is being carried out at 25 power unit facilities, involving more than 850 people – specialists from the Leningrad NPP and employees of contracting organisations of the Holding TITAN-2.

By the end of the year, the first large-sized equipment for unit 7 – a melt localisation device – will be installed. The melt trap and its elements are at the final stage of production and should be delivered to the site in the autumn.