India took a significant step towards energy independence on 6 April 2026, when the indigenously designed and built Prototype Fast Breeder Reactor (PFBR) at Kalpakkam attained first criticality. This moment marked the start of a sustained and controlled nuclear chain reaction in the 500 MWe reactor, a technology India has pursued for decades.
With this achievement, the country formally entered the second stage of the three-stage nuclear power programme envisioned by Homi J Bhabha. The PFBR acts as a national test bed with the potential to unlock vast energy reserves for a growing economy.
This success coincides with an unprecedented one-year extension for India's atomic chief, Dr Ajit Kumar Mohanty. The Appointments Committee of the Cabinet confirmed today that Dr Mohanty will remain head of the atomic energy establishment beyond his scheduled departure this Friday. He will be nearly 68 years old by the conclusion of his term in 2027, making his tenure the longest of any Indian atomic chief.
The PFBR differs from the conventional nuclear reactors India has operated to date. Built by Bharatiya Nabhikiya Vidyut Nigam Limited (BHAVINI) and developed by the Indira Gandhi Centre for Atomic Research, the reactor is designed to multiply India's usable nuclear fuel. While India possesses limited uranium reserves, it holds an abundance of thorium.
The reactor uses mixed oxide fuel containing plutonium recovered from the spent fuel of Pressurised Heavy Water Reactors (PHWRs), effectively closing the first stage of the fuel cycle. The core is surrounded by a blanket of uranium 238, which captures fast neutrons and converts them into plutonium 239. Essentially, the reactor produces more fuel than it consumes.
This breeding capability makes the PFBR a strategic asset. For a nation with scarce uranium, fast breeder reactors act as a bridge, allowing India to stretch uranium supplies while building the fuel base required for the thorium-driven third stage of the programme.
The efficiency of breeder reactors is significant when compared to conventional technology. Dr Ravi B Grover, nuclear scientist and member of the Atomic Energy Commission of India, explains that the fission of one gram of heavy metal per day generates one megawatt.
"In nuclear engineering, we express fuel burn-up in MW days per tonne. The fission of one tonne of heavy metal in a day will produce 1,000,000 MW," Dr Grover noted. "Average fuel burn-up in a PHWR is about 8,000 MW days per tonne. That means a PHWR uses just about 0.8 per cent of the energy potential of heavy metal."
In contrast, fast reactors achieve a burn-up of 100,000 MW days per tonne, using 10 per cent of the energy potential in a single cycle. By recycling fuel five times, the reactor can utilise 50 per cent of the potential. This allows India to convert modest uranium inputs into centuries of reliable electricity.
The attainment of criticality demonstrates that India has mastered one of the world's most complex reactor technologies. Once fully operational, India will become only the second country after Russia to run a commercial-scale fast breeder reactor. Fast reactors require liquid sodium cooling and precise engineering margins, making this transition a testament to India's indigenous manufacturing capabilities.
This breakthrough comes during a period of geopolitical uncertainty. Conflicts in West Asia have highlighted India's vulnerability due to its dependence on imported fossil fuels. Breeder reactors offer a path toward energy sovereignty, reducing the impact of external shocks on the economy.
Nuclear power currently contributes 3 per cent of India's electricity generation, with an installed capacity of 8.78 GW. Government projections suggest this will rise to over 22 GW by the early 2030s, with a long-term target of 100 GW by 2047.
The PFBR at Kalpakkam serves as a proof of concept for a future where India is no longer reliant on imported fuels. By extracting more energy from nuclear material and preparing for thorium utilisation, these reactors provide a nearly limitless reservoir of power. For a nation seeking strategic autonomy, the expansion of breeder technology is a necessity.
