500 MWe Indigenous Nuclear Reactor at Kalpakkam Marks Major Milestone in India’s Three-Stage Nuclear Power Programme
TFP Bureau, New Delhi, April 7,2026: In a major milestone for India’s nuclear energy programme, the 500 MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam Nuclear Complex has successfully attained first criticality, marking the start of a controlled nuclear fission chain reaction.
According to the Press Information Bureau, the criticality was achieved at 8:25 pm on April 6, signalling a historic step towards strengthening the country’s long-term energy security and advancing indigenous nuclear technology capabilities.
The milestone was achieved in the presence of Ajit Kumar Mohanty, Secretary of the Department of Atomic Energy and Chairman of the Atomic Energy Commission of India, along with senior officials including Sreekumar G. Pillai, Allu Ananth and K. V. Suresh Kumar. The reactor achieved criticality after meeting all safety requirements set by the Atomic Energy Regulatory Board.
The PFBR technology and design were developed indigenously by the Indira Gandhi Centre for Atomic Research, a premier research facility under the Department of Atomic Energy. The reactor was constructed and commissioned by Bharatiya Nabhikiya Vidyut Nigam Limited, a public sector enterprise under the department.
Fast Breeder Reactors form a crucial component of India’s long-term nuclear strategy. Unlike conventional reactors, the PFBR uses Uranium-Plutonium Mixed Oxide (MOX) fuel and is surrounded by a blanket of Uranium-238. Fast neutrons convert this material into fissile Plutonium-239, enabling the reactor to generate more fuel than it consumes.
The reactor is also designed to eventually utilise Thorium-232, which can be converted into Uranium-233 to power the third stage of India’s nuclear energy programme. This capability significantly enhances the utilisation of nuclear fuel resources and allows the country to extract more energy from limited uranium reserves while preparing for large-scale thorium use.
With the successful attainment of first criticality, India moves closer to realising the full potential of its three-stage nuclear power programme. Fast breeder technology serves as a bridge between the existing fleet of pressurised heavy water reactors and future thorium-based reactors, leveraging the country’s vast thorium resources for long-term clean energy generation.
Officials said the reactor incorporates advanced safety systems, high-temperature liquid sodium coolant technology and a closed fuel cycle that allows recycling of nuclear materials, improving sustainability and reducing waste.
The achievement also reflects the contribution of hundreds of scientists, engineers and industry partners involved in designing, manufacturing and constructing the reactor using predominantly indigenous technologies. Experts say the fast breeder programme will strengthen India’s capabilities in advanced materials, reactor physics and nuclear fuel cycle technologies while supporting future reactor designs.
As India expands its clean energy portfolio, fast breeder reactors are expected to play a vital role in delivering reliable, low-carbon base-load power. The successful first criticality of the PFBR marks a significant step towards a sustainable and self-reliant energy future for the country.
