Prototype Fast Breeder Reactor Achieves First Criticality

On 6 April 2026, India’s indigenously designed 500 MWe Prototype Fast Breeder Reactor at Kalpakkam attained first criticality, beginning a sustained controlled fission chain reaction after more than two decades of development. Designed by IGCAR and built and commissioned by BHAVINI, the sodium-cooled reactor is the first commercial fast breeder reactor in India. The milestone marked India’s entry into the second stage of its three-stage nuclear-power programme, intended eventually to support wider use of the country’s thorium resources.