India Achieves First Criticality in Fast Breeder Reactor

The 500 MWe PFBR at Kalpakkam, Tamil Nadu, reached initial criticality on April 6 at 8:25 pm, according to the Department of Atomic Energy (DAE). Officials hailed it as "a major milestone in bolstering India's energy security over the long term and elevating its homegrown nuclear expertise."

DAE's Indira Gandhi Centre for Atomic Research (IGCAR) designed and engineered the PFBR technology. Bharatiya Nabhikiya Vidyut Nigam Ltd (BHAVINI), a DAE public sector unit, handled construction and commissioning, starting in 2004 with an initial 2010 target. In mid-2024, India's Atomic Energy Regulatory Board approved the First Approach to Criticality, allowing fuel loading and low-power physics tests. Last August, Minister of State Jitendra Singh informed parliament that commissioning delays stemmed primarily from "novel technological challenges."

BHAVINI noted that first criticality came after fulfilling all safety protocols, with AERB clearance following a thorough evaluation.

"India marks a pivotal moment in its civilian nuclear progress, progressing to the second stage of its programme," Prime Minister Narendra Modi posted on social media. He praised the PFBR as evidence of "our profound scientific prowess and robust engineering. It paves the way to tap our immense thorium resources in the programme's third stage. A moment of national pride."

The PFBR runs on uranium-plutonium mixed oxide (MOX) fuel, encircled by a uranium-238 blanket that absorbs neutrons to produce plutonium-239. This setup lets the reactor produce more fuel than it uses—essentially breeding it. It can also incorporate thorium-232 in the blanket to create uranium-233.

BHAVINI emphasized that this feature maximizes nuclear fuel efficiency, extracting more energy from scarce uranium while gearing up for thorium dominance ahead. The breeder initiative bolsters expertise in fuel cycles, materials, physics, and engineering, laying groundwork for future reactors and advanced nuclear systems.

These fast breeders represent stage two of India's nuclear roadmap, utilizing plutonium from reprocessed fuel of stage-one pressurised heavy water and light water reactors. Stage three involves advanced heavy water reactors to utilize thorium-plutonium fuel and breed uranium-233 for a thorium-centric closed cycle.

The World Nuclear Association reports around 20 fast neutron reactors worldwide since the 1950s, including commercial electricity producers—though not all bred fuel.

India operates 24 nuclear plants totaling roughly 7,900 MW and eyes major growth. Seventeen reactors (13,100 MW total) are in construction (7) or pre-project phases (10). The nation targets 100 GW nuclear capacity by 2047 under its Viksit Bharat vision.