India Achieves Criticality in Advanced Fast Breeder Reactor for Energy Independence
India has announced the criticality achievement of its most advanced nuclear reactor, the Prototype Fast Breeder Reactor located in Kalpakkam, Tamil Nadu. This milestone signifies the initiation of a self-sustaining nuclear chain reaction, a crucial step towards commercial operational status.
Prime Minister Narendra Modi highlighted that the nationally designed and built reactor can produce more fuel than it consumes, showcasing the countrys scientific capabilities. This realisation places India alongside Russia and China as a leader in fast breeder reactor technology, with only these nations operating or testing large-scale reactors of this kind.
While Russia currently operates commercial-scale fast breeder reactors and China has maintained a demonstration reactor since 2023, India aims to evaluate the commercial viability of this 500 megawatt electrical reactor for achieving energy independence. The reactor was visited by Modi in March 2024, marking the commencement of the final testing phase following the start of fuel loading.
The key feature of this reactor is its ability to reproduce fuel through rapid neutrons, which can utilise India's extensive thorium reserves. This capability could potentially lead to complete energy independence, based on data from Indias Department of Atomic Energy.
However, progress has been mired by technical setbacks, including mechanical failures that delayed the reactor's real startup by two years. An audit from Indias Parliamentary Committee of Science and Technology revealed a 16-year delay compared to the original 2010 plan, with costs soaring from an initial estimate of approximately 325 million euros to around 763 million euros as of June 2025.
Following its criticality achievement this week, the reactor will undergo low-power testing supervised by Indias Atomic Energy Regulatory Board, prior to its final connection to the national grid scheduled for late 2026. This development marks a significant step in Indias nuclear and sustainable energy ambitions, with potential implications for global decarbonisation efforts.