India has achieved a major milestone on April 7, 2026, as the Prototype Fast Breeder Reactor (PFBR) at Kalpakkam attained criticality. This marks the start of a self-sustaining nuclear chain reaction and progress in India’s long-term nuclear energy strategy.

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• PFBR at Kalpakkam reached criticality, marking start of controlled nuclear chain reaction.
• Criticality means reactor sustains reaction without external neutron support.
• PFBR is a 500 MW sodium-cooled fast breeder reactor developed indigenously.
• Operated by Bharatiya Nabhikiya Vidyut Nigam Limited at IGCAR.
• Uses plutonium-based fuel instead of conventional uranium fuel.
• Produces more fissile material than it consumes, improving fuel efficiency.
• Marks India’s entry into second stage of three-stage nuclear programme.
• Based on vision of Homi Jehangir Bhabha.
• Enables future transition to thorium-based nuclear energy systems.
• Strengthens energy security and supports clean energy goals like net zero 2070.