India Achieves First Criticality Of 500 MWe PFBR At Kalpakkam, Boosting Nuclear Energy Ambitions

India marked a major step in its nuclear energy journey on April 6, 2026, when the 500 MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam nuclear facility achieved its first criticality. This means the reactor has started a controlled and continuous nuclear chain reaction for the first time, officially entering its operational phase.

The PFBR has been developed by the Indira Gandhi Centre for Atomic Research and constructed by BHAVINI, a public sector company. It is one of the most advanced reactors in the world and currently the only fast breeder reactor of this size operating outside Russia. Unlike conventional nuclear reactors, this technology can produce more fuel than it consumes. It uses a mix of uranium and plutonium, along with a special blanket material that converts into new fuel during operation.

This development is important for India’s long-term energy security. The country has limited uranium reserves but large deposits of thorium. The PFBR plays a key role in India’s three-stage nuclear program by helping transition towards thorium-based power generation, which can provide large-scale, clean, and reliable electricity in the future.

The project also reflects the success of the government’s self-reliance push. Most of the equipment, materials, and technologies used in building the reactor were developed within India, reducing dependence on foreign sources for critical infrastructure.

The entire process was closely monitored by the Atomic Energy Regulatory Board, which ensured that all safety standards were met. After achieving first criticality, the reactor will now go through several stages of testing, where its power output will be gradually increased.

Once fully operational, the PFBR will supply stable electricity to the national grid and support India’s clean energy goals. This milestone also opens the door for future fast breeder reactors, bringing India closer to a sustainable and long-term nuclear energy solution.