Kalpakkam | Fast Breeder Reactor
The Road to Thorium India’s first Fast Breeder Reactor (FBR) at Kalpakkam crossed a significant milestone in the first week of April 2026 when it attained criticality. If all goes to plan, when it is fully commissioned later this year, it will become one of the very few operational fast breeder reactors in the world. This is significant news. It opens up the possibility of India moving towards near energy independence and reducing geopolitical chokepoints on its growth trajectory by unlocking the vast potential of thorium. India has the world’s largest reserves of thorium, a resource that is often described—sometimes rather casually—as capable of powering the country for thousands of years. The claim is seductive, but it raises a more immediate question: how far are we, really, from turning that promise into reality? The answer lies not in thorium alone, but in understanding the layered logic of nuclear physics and the long, deliberate pathway designed to reach it. At the heart of nucl...