Kalpakkam Prototype Fast Breeder Reactor Achieves First Criticality
The 500 MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, Tamil Nadu achieved first criticality — a landmark moment in which a self-sustaining nuclear chain reaction is initiated for the first time.
Prime Minister Modi hailed the development as a "proud moment" and a "defining step" in India's civil nuclear journey.
The reactor is implemented by BHAVINI (Bharatiya Nabhikiya Vidyut Nigam Ltd), a Government of India enterprise under the Department of Atomic Energy.
Fuel loading for the PFBR commenced in October 2025 after AERB (Atomic Energy Regulatory Board) clearance, following resolution of first-of-a-kind technical issues.
India becomes only the second country after Russia to operate a commercial-scale fast breeder reactor.
India's Three-Stage Nuclear Power Programme
Conceived by physicist Homi Bhabha in the 1950s, India's three-stage nuclear programme was designed to achieve long-term energy independence using the country's abundant thorium reserves — estimated at about 25% of global known reserves — while working around its limited uranium reserves (only 1–2% of global reserves).
PFBR achieving criticality means India has now physically entered Stage 2 of its three-stage nuclear programme, over 70 years after it was first conceptualised by Bhabha.
Fast Breeder Reactor Technology
A fast breeder reactor uses fast neutrons (unlike thermal reactors that slow neutrons) to cause fission in fuel and, crucially, to convert fertile material (U-238 or Th-232) into fissile material (Pu-239 or U-233). The result is that the reactor "breeds" more fuel than it consumes, making it a critical technology for countries with limited uranium but large thorium reserves.
The PFBR's criticality validates India's indigenous fast breeder technology, developed entirely without foreign assistance due to technology-denial regimes India faced after its 1974 nuclear test.
Nuclear Energy and India's Energy Security
India's installed nuclear capacity is approximately 7,480 MW (as of 2025), contributing about 3% of total electricity generation. With targets of 100 GW nuclear capacity by 2047, fast breeders are pivotal — projections suggest Stage 2 and 3 reactors could power India with thorium for thousands of years.
With domestic coal reserves facing depletion pressures and climate commitments, the PFBR's commissioning represents a strategic step toward low-carbon, fuel-secure baseload electricity generation.
- Reactor type: Sodium-cooled Fast Breeder Reactor (FBR)
- Capacity: 500 MWe
- Location: Kalpakkam, Tamil Nadu (also home to MAPS — Madras Atomic Power Station)
- Implementing agency: BHAVINI (Bharatiya Nabhikiya Vidyut Nigam Ltd)
- Regulatory body: AERB (Atomic Energy Regulatory Board)
- Fuel loading began: October 2025
- India is the 2nd country (after Russia) to operate a commercial-scale fast breeder reactor
- India holds ~25% of the world's known thorium reserves
- India's uranium reserves: only ~1–2% of global reserves
- Three-stage nuclear programme conceived by: Dr. Homi Jehangir Bhabha (1950s)
- The programme is managed under the Department of Atomic Energy (DAE), which reports directly to the Prime Minister