Kalpakkam:India's Indigenously Developed Atomic Reactor Attains Criticality
Context:
On April 6, 2026, the 500 Megawatt electric (MWe) Prototype Fast Breeder Reactor (PFBR) located at Kalpakkam, Tamil Nadu, successfully attained its first criticality.
The Prime Minister hailed this landmark achievement as a defining step forward in India's civil nuclear journey, showcasing the country's scientific depth and engineering self-reliance under the Aatmanirbhar Bharat initiative.
What is "Criticality"?
Self-Sustaining Reaction:
Attaining "criticality" is a crucial operational milestone indicating that the nuclear reactor core has successfully achieved a controlled, self-sustaining nuclear fission chain reaction.
Precursor to Power Generation:
This is a vital validation step before the reactor begins full power generation, confirming that the core is functioning exactly as designed by the scientists.
About the Prototype Fast Breeder Reactor (PFBR):
Indigenous Development:
The PFBR's technology was designed entirely by the Indira Gandhi Centre for Atomic Research (IGCAR) and built by Bharatiya Nabhikiya Vidyut Nigam Ltd (BHAVINI).
It features massive hardware and structural contributions from over 200 Indian industries, including several MSMEs.
The "Breeder" Concept:
Unlike conventional thermal reactors, a fast breeder reactor is uniquely capable of producing more nuclear fuel than it actually consumes during its operation.
The PFBR utilizes a Uranium-Plutonium Mixed Oxide (MOX) fuel core, surrounded by a blanket of Uranium-238.
Fast neutrons convert this fertile U-238 into fissile Plutonium-239, thereby actively "breeding" additional fuel.
Significance for India's Nuclear Strategy:
The Second Stage:
The operationalization of the PFBR marks a massive leap in the second stage of India's long-term, three-stage nuclear energy programme.
Global Standing:
Once fully operational, India will officially become only the second country in the world, after Russia, to operate a commercial fast breeder reactor.
Gateway to Stage Three:
Crucially, the reactor is designed to eventually use Thorium-232 in its blanket.
Through transmutation, this will be converted into Uranium-233, laying the foundational groundwork for the third stage of the programme which aims to harness India's vast domestic thorium reserves.