The RPV, which weighs about 330 tonnes, is one of the largest reactor components, a vessel containing the nuclear reactor coolant, core shroud, and the reactor core and fuel.
Construction of the Generation III Kudankulam-3, a Russia-procured VVER- V-412, 917-MW pressurised water reactor, began in June 2017.
There are three other units of the same design under construction at the site. Kudankulam-4 was started in 2017 and Kudankulam-5 and -6 in December 2021.
Kudankulam-1 and -2, also both VVER V-412 units, have been in commercial operation since December 2014 and March 2017 respectively.