MUMBAI: The fifth unit of the 1,000-MW Kudankulam Nuclear Power Project in Tamil Nadu—a joint Indo-Russian project—crossed a significant milestone on Monday with the erection of reactor pressure vessel inside the reactor building for its fifth unit, according to Nuclear Power Corporation of India Limited (NPCIL). Current indications suggest that the fifth unit is slated to become operational towards the end of this year.This was done after clearance from Atomic Energy Regulatory Board. The reactor pressure vessel is the heart of a nuclear power plant that houses the reactor core where nuclear fission reaction takes place. The vessel, weighing approximately 320 tonnes, was lifted and installed using a specialised heavy-lift crane.NPCIL said, “This milestone reflects the close coordination and dedicated efforts of NPCIL and Atomstroyexport, Russian Federation. The successful erection of the vessel demonstrates the steady progress being made towards the completion of Unit 5, reinforcing NPCIL’s commitment towards nation’s clean energy transition,” it said.The Kudankulam site comprises six units, each of 1,000 MW capacity. Of this, units 1 and 2 are already operational. As of May 2026, they have cumulatively generated about 130 billion units of electricity, averting the release of about 112 million tonnes of CO2 equivalent into the environment.According to NPCIL, the third and fourth units are at an advanced stage of construction. The fifth and sixth units are at different stages of construction and are planned to be commissioned progressively. “Upon completion of these projects, Kudankulam site will have a total installed capacity of 6,000 MW,” it said.