Welding of the main circulation pipeline (GTsT – Glavnii Tsirculyatsionnii Truboprovod) is underway at unit 2 of Russia’s Kursk-II NPP. The GTsT connects the main equipment of the primary circuit – reactor vessel, steam generators and main circulation pumps. The technological process begins with the assembly of pipeline components for welding, which is carried out in accordance with the technical requirements.

Rigid requirements are imposed on welded joints of the GTsT, since the water temperature of the primary circuit at the outlet of the reactor will be 328°C. Water circulation will be carried out under a pressure of 160 atmospheres, which is comparable to the water pressure at a depth of about 1,600 metres, explained Kursk NPP Director Alexander Uvakin. “Welding of the primary circuit pipelines is subject to certain conditions – clean installation areas, special temperature mode (not less than 10°C), humidity (not more than 60%) and complete absence of drafts.”

Specialists from JSC Energospetzmontazh will manually perform 32 welded joints. The total mass of pipelines and metal structures weighs more than 250 tonnes. GTsT walls are made of special steel with a thickness of 70mm. “GTsT welding is a complex construction operation that includes several stages: preparation, welding, heat treatment, control and the final stage – austenitic float. All work will be carried out by highly qualified personnel.” Oleg Shperle, Vice President of Atomstroyexport JSC (part of Rosatom) and Director of the Kursk-II construction project. The welding is expected to take around 80 days.

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: Specialists from JSC Energospetsmontazh will manually perform 32 welded joints on the main circulation pipeline (courtesy of Rosatom)