Tests of a heavy crawler crane with a lifting capacity of 2,000 tonnes and a special multi-vector traverse have been successfully completed at the construction site of the new Leningrad NPP units. 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), now under construction, will replace units 3&4.
The crane will be used in the near future to install the first tier of the internal containment (VZO – Vnutrennei Zatsitnoi Obolochki) in the reactor building of unit 7 (also known as Leningrad-II unit 3). During operation, the VZO will serve as one of the passive safety systems of the power unit. It will prevent the release of radioactive substances and ionising radiation from the building.
During the tests, the crane lifted a metal frame with a test weight of 500 tonnes to a height of one hundred millimetres and held it in this position for 10 minutes, lowering it back to the site. “The crane and the traverse have confirmed their operability and reliability, the ability to lift and move bulky loads,” said Evgeny Milushkin, Deputy Director for Capital Construction and Head of the Leningrad-II Capital Construction Department. “The crane operator and the slingers also worked as expected. It is possible to proceed with the next key operation at unit 7 – the installation of the lower tier of the inner protective shell. We plan to complete this task in the near future.”
It is noteworthy that the specialists of the general contractor made the rigging traverse themselves. The entire production of this equipment took several months and was carried out in Sosnovy Bor, the industrial zone of the Leningrad NPP satellite city.
About 40 highly qualified specialists of the Northern Construction Directorate (SUS – Severnoi Upravlenie Stroitelstva) of TITAN-2 Holding participated in the cutting of metal sheets, their assembly and welding. They also undertook geodetic surveys to confirm the correctness of the assembly of the elements and to exclude deviations from the design dimensions, as well as other related work. As a result, a structure weighing more than 30 tonnes was created, which, together with the crane, will have to install assembled and welded elements of the inner containment in the reactor building – five tiers of the cylindrical part of the building and two tiers of the dome.
“The height of the first tier of the inner containment is 10 metres, the diameter is 44 meters, the weight is 146 tonnes, and the weight of the mounted element will be 227 tonnes,” said Viktor Sharofeev, Head of the Production Planning & Implementation Department of the SUS Production Directorate (TITAN-2 Holding). “To install this powerful metal structure on the reactor building precisely, carefully and safely, we designed and manufactured a special multi-vector traverse, which includes 18 steel slings. Slings attached to the traverse on one side and to the containment on the other will evenly distribute the load and help move the tier smoothly to its original location. The remaining tiers will also be carefully installed later, some of them will have a slightly greater weight than the first tier.”
Mikhail Sidorov, Director of the VZO SUS Directorate, noted: “We have extensive experience in the manufacture of containment structures for VVER-1200 power units and accessories for their movement and installation. Our traverses reliably and safely carry out lifting operations at nuclear power plants currently being built by Russia in Egypt and Turkey. I am confident that the installation of the first tier of the VZO at the third VVER-1200 power unit of the Leningrad NPP will be carried out without any difficulties, and the shell, after installation and concreting, will reliably perform its functions.”
