Overhead view of the reactor pressure vessel assembly as the head is positioned

Major equipment for India's Kudankulam 5 is complete at the factory of the Russian supplier, Atommash. The reactor pressure vessel was assembled in a trial and the pressuriser passed crucial tests.

The Kudankulam nuclear power plant is about 100 kilometres from the port city of Tuticorin in the state of Tamil Nadu at the southern tip of India. The Russian export project has two large VVER-1000 reactors in operation while four more are currently under construction. Units 3 and 4 began construction in 2017 and units 5 and 6 followed in 2021.

The reactor pressure vessel is central to a nuclear power plant. It contains the nuclear fuel assemblies which produce heat and forms part of the primary coolant circuit. It needs to be able to be opened for refuelling and also contains provisions for sensors and moving parts such as control rods.

The entire assembly for Kudankulam 5 was put together at Atommash's factory in Volgodonsk, Russia, using a deep recess in the concrete floor that simulates the position the vessel will hold in the real power plant. First, the 11-metre-long body of the vessel was lowered into place using a crane with a lifting capacity of 600 tons. Then a 10-metre hull weighing 73 tons was placed inside, as was a 38-ton fence and further items adding up to another 68 tons. Once the reactor vessel head was attached and closed the entire component was some 603 tons.

Performing the assembly will significantly reduce installation time on site, Atommash said.

Kudankulam 5's pressuriser during testing

Meanwhile, at Atommash's Izhora plant near Saint Petersburg, another major component of Kudankulam 5's primary circuit was tested - its pressuriser. This will maintain the appropriate pressure of the coolant water used to transfer heat from fuel assemblies in the reactor pressure vessel to the steam generators. This was successfully taken to its maximum permissible value of 24.7 MPa before acceptance. It is now being prepared for shipment, said Atommash.