India has achieved a major milestone in its nuclear energy programme after the Prototype Fast Breeder Reactor (PFBR) at Kalpakkam in Tamil Nadu achieved criticality, marking the point at which a nuclear chain reaction becomes self-sustaining.
The development is being seen as a significant step toward long-term energy independence for the country, which has pursued fast breeder reactor technology for decades despite several developed nations scaling back similar programmes.
Unlike conventional nuclear reactors, fast breeder reactors produce more fissile fuel than they consume. The PFBR uses plutonium as fuel and has a breeding ratio of around 1.05, meaning it generates slightly more fuel than it burns.
India’s nuclear strategy was originally designed by physicist Homi Jahangir Bhabha through a three-stage programme tailored to the country’s limited uranium reserves and large thorium deposits. The first stage uses natural uranium in Pressurised Heavy Water Reactors, producing plutonium as a by-product. That plutonium is then used in breeder reactors such as the PFBR.
Sreekumar Pillai, Director of the Indira Gandhi Centre for Atomic Research at Kalpakkam, said the achievement fulfilled a long-standing goal for India’s nuclear community.
India has continued developing breeder technology even as countries such as Japan, France, and the United States scaled back their programmes because of safety concerns, high costs, and operational challenges.
A key part of India’s long-term plan involves thorium. The country holds around 25 per cent of the world’s thorium reserves. According to Pillai, once thorium-based systems are fully deployed, India could secure energy supplies for 500 to 700 years.
The PFBR currently remains in a low-power state while safety tests and reactor physics experiments are conducted. Electricity generation is expected later this year following regulatory approval.
India is also developing additional fast breeder reactors and a dedicated fuel cycle facility at Kalpakkam as part of its broader goal of reaching 100 gigawatts of nuclear capacity by 2047 and net zero emissions by 2070.