India’s indigenously designed Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, Tamil Nadu successfully attained its first criticality on 6th April 2026, marking the initiation of a sustained nuclear chain reaction. Built by Bharatiya Nabhikiya Vidyut Nigam Limited (BHAVINI), the PFBR is a 500 MWe reactor located at the Kalpakkam Nuclear Complex.
With this, India has officially entered the Second Stage of its three-stage nuclear power programme, a vision first conceived by Dr. Homi Jehangir Bhabha, the architect of India’s nuclear programme. Once fully operational, India will become only the second country in the world after Russia to operate a commercial fast breeder reactor.
Fast Breeder Reactors are a cornerstone of India’s long-term nuclear strategy. Unlike conventional thermal reactors, the PFBR uses Uranium-Plutonium Mixed Oxide (MOX) fuel. The core of PFBR is surrounded by a blanket of Uranium-238.
- Fast neutrons convert fertile Uranium-238 into fissile Plutonium-239, enabling the reactor to produce more fuel than it consumes.
- The reactor is designed to eventually use Thorium-232 in the blanket.
- Through transmutation, Thorium-232 will be converted into Uranium-233, which will fuel the third stage of India’s nuclear power programme.
India’s Three-Stage Nuclear Power Programme
India holds limited uranium reserves but possesses one of the world’s largest thorium reserves. To leverage this, the Department of Atomic Energy (DAE) designed a three-stage programme based on a closed nuclear fuel cycle. The goal is to progressively multiply domestic fissile resources and secure long-term energy independence.
- Stage 1: Pressurised Heavy Water Reactors (PHWRs): Natural uranium is used as fuel. Spent fuel produces plutonium, which becomes primary input feeding Stage 2. This stage is operational.
- Stage 2: Fast Breeder Reactors (FBRs): Plutonium from Stage 1 fuels FBRs, which generate more fuel than they consume. These reactors breed Uranium-233 from Thorium for Stage 3. This stage has now entered with PFBR criticality
- Stage 3: Thorium-Based Reactors: Uses India’s vast thorium reserves at scale, with Uranium-233 (bred in Stage 2) as fuel- the key to India’s long-term energy security.
Each stage feeds into the next, making India’s nuclear programme one of the most forward-looking energy strategies in the world.
PFBR- Key Technical Features
The PFBR’s technology was developed by the Indira Gandhi Centre for Atomic Research (IGCAR) under DAE.
- Fuel: Uranium-Plutonium Mixed Oxide (MOX) fuel, recovered from reprocessed spent fuel of PHWRs
- Breeds More Than It Burns: Core surrounded by a blanket of Uranium-238; fast neutrons convert it into fissile Plutonium-239
- Bridge to Stage 3: Designed to eventually use Thorium-232 in the blanket, converting it into Uranium-233 through transmutation
- Closed Fuel Cycle: Spent fuel from PFBR is reprocessed and recycled back — closing the Stage 2 fuel cycle
India’s Current Nuclear Power Landscape
- Installed Capacity: 78 GW
- Electricity Generated (2024–25): 56,681 Million Units
- Share in total electricity generation: ~1% (2024–25)
- Projected Capacity by 2031–32: 38 GW (nearly 3x current capacity)
- Civil Nuclear Cooperation Agreements: Signed with 18 countries
Nuclear Energy Mission & Long-Term Vision
- The government has announced the Nuclear Energy Mission under Union Budget 2025–26, targeting 100 GW of nuclear capacity by 2047, aligned with India’s net zero emissions goal by 2070.
- Key measures include a financial allocation of ₹20,000 crore for Small Modular Reactors (SMRs), with at least 5 indigenously designed SMRs operational by 2033.
- BARC is developing next-generation designs including the 200 MWe Bharat Small Modular Reactor (BSMR-200), the 55 MWe SMR-55, and a High-Temperature Gas-Cooled Reactor (up to 5 MWth) for hydrogen generation.
- The SHANTI Act, 2025: Sustainable Harnessing and Advancement of Nuclear Energy for Transforming India– has been enacted to modernise India’s nuclear legal framework and enable limited private participation under regulatory oversight.