In a statement Rosatom said the reactor pressure vessel and core melt localisation device or core catcher has been shipped in a cargo vessel from St.Petersburg, Russia.
The scheduled arrival at the Kudankulam construction site is January 2020.
The two major components are for the fourth 1,000 MW atomic power plant coming up at Kudankulam in Tamil Nadu belonging to Nuclear Power Corporation of India Ltd (NPCIL).
"In spite of inherent difficulties due to the pressure under which the port is operating at the end of the year, we fulfilled our obligations towards the Customer and shipped the necessary equipment," Alexander Kvasha, First Deputy Director for Projects in India at ASE, engineering division of Rosatom was quoted as saying in the statement.
Rosatom is technical consultant and main equipment supplier for the Kudankulam Nuclear Power Project (KNPP).
The core catcher, the reactor vessel with internals and the steam generators are the most essential equipment, critical for the construction of the reactor. It was 13th shipment for Unit 4.
A core melt localisation device is one of the most important passive safety systems of modern nuclear power plant of Russian design.
It is installed at the bottom of the plants's protective shell. It is designed to localise and cool the molten core material in case of an accident that could lead to damage to the core.
The "core catcher" allows the integrity of the protective shell to be preserved and thus excludes radioactive emission in the environment, even if the hypothetical accident is serious.
The passive safety systems are capable of functioning even in the event of a complete loss of power supply.
They can provide full safety without the active systems and an operator.
( With inputs from IANS )