Rosatom has completed welding of the main circulation pipeline (GTsT - Glavnii Tsirculyatsionnii Truboprovod) at unit 2 of Russia’s Kursk-II NPP. The GTsT connects the main equipment of the reactor unit into a single technological system, forming the primary circuit. It circulates water from the reactor to the steam generators. It comprises 20 components with a total weight of more than 250 tonnes connected by welded joints.
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.
For power units with VVER-TOI reactors, the main circulation pipeline is connected by 32 joints (four more for the VVER-1200 because of the location of the steam generators relative to the reactor vessel in an airtight compartment). The wall thickness is 70 mm which is the main difficulty in welding. According to the schedule, 70 days were allotted for the welding and heat treatment of the joints, but the work was completed in a record 50 days. A similar operation at unit 1 was completed in 2023 in 55 days. The reduced time was due to preliminary preparation, optimisation of the work schedule, as well as with the parallel execution of several processes based on experience gained at unit 1 and other NPPs.
“GTsT welding is a large complex of related works. Preparation begins in a year in advance. We try to ensure the welders do not change from unit to unit. This gives us confidence in the high quality of work, and their experience guarantees a reduction in welding time as we have confirmed.” said Ildar Tleubaev, director of the LSG-5 branch of Energospetzmontazh.
During the welding process, specialists carried out step-by-step control of all operations performed: visual, measuring, radiographic, capillary and ultrasonic. The quality of the seams met all the required standards. “The completion of the GTsT welding paves the way for the start of installation of security systems and other technological systems that adjoin them. Said Oleg Shperle, Vice President of Atomstroyexport and Director of the project for the construction of Kursk -II.
Image courtesy of Kursk NPP
