Achieved first criticality on 6 April 2026 at 08:25 PM IST. Uses Uranium-Plutonium Mixed Oxide fuel. Core surrounded by Uranium-238 blanket designed to eventually use Thorium-232. Construction began in 2004 with original completion target of 2010. Cost escalated from original Rs 3492 crore to Rs 8181 crore. Designed by IGCAR. On attaining criticality, India became only the second country after Russia to operate a commercial fast breeder reactor. Fast Reactor Fuel Cycle Facility expected December 2029. Pre-project activities approved for twin FBR 1 and 2 units at same site. Status note (October 2026): first criticality on April 6, 2026 was confirmed by India's Press Information Bureau, and NucNet reported that a date for commercial operation had not been set. The September 2026 date shown for this project came from a single secondary report and has passed with no confirmed grid connection or commercial-operation date.