India’s Prototype Fast Breeder Reactor (PFBR) at Kalpakkam is a key part of the country’s three-stage nuclear power program.
The project has faced long delays because of complex new technologies, but once completed, it will play a major role in boosting India’s nuclear energy and making better use of its uranium and thorium reserves.
Kalpakkam’s 500 MWe Reactor to Strengthen Energy Security
The Prototype Fast Breeder Reactor (PFBR) at Kalpakkam is one of the most important projects in India’s three-stage nuclear power program.
However, the project has been delayed for many years because of “first-of-its-kind” technical problems that came up during the testing and commissioning phase.
India’s Atomic Energy Minister, Jitendra Singh, informed the Parliament in August 2025 that these challenges are being carefully resolved with the help of the reactor’s designers and experts.
The PFBR is being built by BHAVINI (Bharatiya Nabhikiya Vidyut Nigam Limited) under the Department of Atomic Energy.
It is a 500-megawatt electric (MWe) sodium-cooled fast breeder reactor that will add a major boost to India’s nuclear energy production.
Construction of the reactor began in 2004 and was originally supposed to be completed in 2010. But due to repeated delays and technical issues, the project has stretched on for over two decades.
The latest update says the PFBR is now expected to achieve criticality (start a controlled nuclear chain reaction) by March 2026 and full power generation by December 2026.
A big milestone was reached in August 2024 when the Atomic Energy Regulatory Board (AERB) gave permission for the First Approach to Criticality.
This allowed the loading of the reactor core with uranium-plutonium mixed oxide fuel and the start of low-power physics tests.
Still, the unique and complex technology of the PFBR has brought new challenges, which are now being solved step by step.
Once the reactor starts running, it will be able to recycle and reuse spent nuclear fuel, helping India make the most of its limited uranium and abundant thorium reserves.
India’s three-stage nuclear program was first planned by Dr. Homi Bhabha:
Stage 1 – Pressurized Heavy Water Reactors (PHWRs), which use natural uranium to produce electricity and plutonium.
Stage 2 – Fast Breeder Reactors (like the PFBR), which use plutonium to produce more fuel than they consume.
Stage 3 – Advanced Heavy Water Reactors (AHWRs), which will run on thorium and achieve a self-sustaining fuel cycle.
The first stage is already well established in India. The PFBR represents the second stage, and once it becomes fully operational, it will make the transition towards the third stage possible.
In short, the PFBR has faced many setbacks because of its complex and pioneering technology, but it remains a crucial project for India’s long-term energy security.
By enabling the use of thorium and closing the nuclear fuel cycle, it will secure India’s place as a leader in sustainable nuclear power.
