Construction began 29 June 2021. Physical progress 41.56 percent as of March 2026. Reactor Pressure Vessel for Unit 5 installed on 15 June 2026 using open-top method. Manufactured at Atommash plant in Volgodonsk, Russia. Atomic Energy Regulatory Board granted permission for major equipment erection on 2 May 2026. Update (October 2026): the reactor pressure vessel was installed at Unit 5 of the Kudankulam plant in Tamil Nadu, India on June 15, 2026 (NPCIL release and World Nuclear News, June 16, 2026). The vessel weighs about 320 tonnes (one record said 300 tons), was manufactured at Rosatom's Atommash plant in Volgodonsk, Russia and delivered to the site in 2025, and was placed with a heavy-lift crane after AERB clearance for major equipment erection; it marks the start of erection of the nuclear steam supply system equipment, with the steam generators and main circulation pumps to follow. NPCIL and Atomstroyexport (Rosatom) are jointly implementing the project under the 1988 India-Russia intergovernmental agreement. The Kudankulam site is to have six VVER-1000 units totalling 6,000 MWe; units 1 and 2 are in commercial operation and had generated about 130 billion units of electricity by May 2026, avoiding about 112 million tonnes of CO2, while units 3 to 6 are at various stages of construction. Unit 5's construction began on June 29, 2021 and unit 6's on December 20, 2021. The original schedule (66 and 75 months from 2021) pointed to December 2026 and September 2027, but Rosatom's CEO said on September 14, 2026 that commissioning operations for units 5 and 6 will begin in 2028-2029, and the projected operational date is set to the start of that window; earlier records in this database gave December 2026, December 2028 and December 2029.