Reactor dome installed at unit 2 of Russia’s Kursk-II NPP

19 December 2023

The dome of the outer containment shell (NZO) has been installed at unit 2 of the Kursk-II NPP. The dome is the last part of the NZO. Initially, the sixth tier was installed - the lower component of the dome - a large-sized structure weighing more than 215 tonnes. Two days later, the upper part the dome itself, weighing 195 tonnes, with a diameter of 34.7 metres and a wall thickness of 1.5 metres was put in place. The height of the reactor building is now 64.9 metres, and after concreting will reach 65.4 metres.

Earlier in December, the VVER-TOI reactor pressure vessel (RPV) was installed at unit 2. Installation of the RPV marked the active stage of installation of all primary circuit equipment signalling the countdown to commissioning. The equipment was installed ahead of the construction schedule.

“The construction project of Kursk-II provides for two protective shells of the reactor building - internal and external,” said Kursk NPP Director Alexander Uvakin. “The internal one prevents the release of radioactive substances into the environment in emergency situations. The external one, together with the internal one, serves as physical protection from natural and man-made external influences, including earthquakes, hurricanes and plane crashes. The construction of the internal containment shell (VZO) was completed at the end of December last year.” 

Double containment is a distinctive feature of NPPs with VVER-1200 and VVER-TOI reactors. The distance between the inner and outer shells is 1.5 metres. This design feature is being used for the first time at generation 3+ NPPs. The installation of each tier of both shells was preceded by the assembly of the component elements, at a special site near the reactor building. Time savings were achieved thanks to the effective interaction of all those involved in this operation, as well as due to the implementation of a project to maximise enlargement of unit structures.

“The stage of preparation and assembly of the NZO dome is a long and painstaking process; according to the plan, it takes 101 days,” said Oleg Shperle, Vice-President of Atomstroyexport JSC and project director for the construction of Kursk-II. “At the Kursk-II construction site, the assembly of the two parts of the dome was completed by specialists in 86 days, thanks to the well-coordinated interaction of the builders.” Completion of the installation of the outer containment shell is an important step towards the physical start-up of the unit. In the spring of 2024, work on concreting the dome will begin, and after the completion, installation of a passive heat removal system (PHRS) will begin.

Kursk II will replace the currently operating Kursk NPP, which comprises four ageing RBMK reactors (one of which is already closed). Units 1&2, currently under construction, will have VVER-TOI reactors – a development of the VVER-1200 reactor design. The VVER-TOI has increased power and improved technical and economic indicators, as well as increased resistance to extreme external influences. Currently work is being carried out at 156 facilities on the Kursk-II site. The number of construction and installation personnel is more than 8,500.

Image courtesy of Rosenergoatom

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