Prototype Fast Breeder Reactor at Kalpakkam Attains First Criticality

The 500 MWe Prototype Fast Breeder Reactor (PFBR) achieved first criticality, marking a major development for India's nuclear energy sector. This historic milestone occurred on April 6, 2026, at 08:25 PM, bolstering the nation's long-term energy security and advancing indigenous nuclear technology.

The criticality was achieved in the presence of Dr Ajit Kumar Mohanty, Secretary, DAE & Chairman, AEC, Shri Sreekumar G. Pillai, Director, IGCAR, Shri Allu Ananth, CMD-In-Charge, BHAVINI, and Shri K.V. Suresh Kumar, Former CMD, BHAVINI & Homi Sethna Chair. This event followed the fulfillment of stipulations from the Atomic Energy Regulatory Board (AERB).

The technology development and design for the PFBR were indigenously executed by the Indira Gandhi Centre for Atomic Research (IGCAR), an R&D Centre under the Department of Atomic Energy. The construction and commissioning are being handled by Bharatiya Nabhikiya Vidyut Nigam Ltd (BHAVINI), a PSU under the Department of Atomic Energy.

Fast Breeder Reactors are fundamental to India's long-term nuclear strategy. Unlike traditional thermal reactors, the PFBR utilizes Uranium-Plutonium Mixed Oxide (MOX) fuel. The reactor core is enveloped by a blanket of Uranium-238. Fast neutrons facilitate the conversion of fertile Uranium-238 into fissile Plutonium-239, enabling the reactor to generate more fuel than it consumes. The design further accounts for the eventual use of Thorium-232 in the blanket. Through transmutation, Thorium-232 is converted into Uranium-233, which will power the third stage of India's nuclear power program.

This capability significantly improves the utilization of nuclear fuel resources, allowing the country to draw greater energy from its finite uranium reserves while preparing for the future large-scale deployment of thorium.

Achieving first criticality propels India closer to realizing the full potential of its three-stage nuclear power program. Fast breeder technology acts as a crucial link between the current fleet of pressurized heavy water reactors and the future deployment of thorium-based reactors, thereby capitalizing on India's extensive thorium resources for enduring clean energy generation.

The successful achievement of this milestone underscores the strength of India's indigenous design, engineering, and manufacturing ecosystem. The reactor integrates advanced safety systems, high-temperature liquid sodium coolant technology, and a closed fuel cycle approach that facilitates the recycling of nuclear materials, thereby enhancing sustainability and minimizing waste.

The project also reflects the contributions of numerous scientists, engineers, technicians, and industry partners who worked on the design, fabrication, and construction of the reactor, relying predominantly on indigenous technologies and components. Their efforts emphasize the nation's increasing proficiency in advanced nuclear engineering and reaffirm India's commitment to technological self-reliance, aligning with the goals of Atmanirbhar Bharat.

Furthermore, the fast breeder program strengthens strategic capacities in areas such as nuclear fuel cycle technologies, advanced materials, reactor physics, and large-scale engineering. The knowledge and infrastructure built through this program will support future reactor designs and next-generation nuclear technologies.

As India expands its clean energy portfolio, fast breeder reactors are positioned to deliver reliable, low-carbon, base-load power with higher thermal efficiency. The attainment of first criticality signifies not only a technological milestone but also a major step toward a sustainable and self-reliant energy future for Viksit Bharat.