**Executive Summary**
On April 6, 2026, India’s indigenously designed 500 MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam attained first criticality, marking the country’s official entry into the second stage of its three-stage nuclear power programme. This milestone supports India’s long-term mission to achieve 100 GW of nuclear capacity by 2047 and net-zero emissions by 2070. The transition facilitates a closed fuel cycle intended to eventually harness India’s vast thorium reserves for sustainable energy security.
**Key Points / Main Content**
**PFBR Technical and Strategic Milestones**
* The PFBR attained criticality on April 6, 2026, initiating a sustained and controlled nuclear fission chain reaction.
* Developed by BHAVINI and IGCAR, the 500 MWe reactor makes India only the second country after Russia to operate a commercial fast breeder reactor.
* The reactor uses Uranium-Plutonium Mixed Oxide (MOX) fuel and a Uranium-238 blanket to "breed" more fuel (Plutonium-239) than it consumes.
* The system acts as a bridge to Stage 3 by transmuting Thorium-232 into Uranium-233.
**India’s Three-Stage Nuclear Programme**
* **Stage 1:** Utilizes Pressurised Heavy Water Reactors (PHWRs) and natural uranium to produce power and plutonium.
* **Stage 2:** Employs Fast Breeder Reactors (FBRs) using plutonium to multiply domestic fissile resources.
* **Stage 3:** Focuses on Thorium-based reactors to utilize India’s extensive thorium reserves for long-term energy independence.
**Policy and Legislative Framework**
* **SHANTI Act, 2025:** Modernizes the legal framework and enables limited private sector participation in the nuclear sector under regulatory oversight.
* **Nuclear Energy Mission:** Outlined in the 2025–26 Union Budget to drive the goal of 100 GW capacity by 2047.
* **Financial Commitment:** Rs 20,000 crore allocated for the design and deployment of Small Modular Reactors (SMRs).
**Future Expansion and Research**
* Nuclear capacity is projected to grow from the current 8.78 GW to 22.38 GW by 2031–32.
* The government aims to have at least five indigenous SMRs operational by 2033.
* BARC is currently developing next-generation designs, including the 200 MWe Bharat Small Modular Reactor (BSMR-200) and hydrogen-generation reactors.
**Impact Analysis**
**Department of Atomic Energy (DAE) & Research Institutions (IGCAR/BARC)**
**Impact**
The successful criticality of the PFBR validates decades of indigenous R&D and shifts the operational focus from the construction phase to the power generation and recycling phase.
**Action Required**
Must lead the development of next-generation SMRs and manage the transition toward Stage 3 thorium-based fuel cycles.
**Private Sector Entities**
**Impact**
The enactment of the SHANTI Act, 2025, opens previously restricted avenues for investment and collaboration within the nuclear energy sector.
**Action Required**
Interested parties must align with new regulatory frameworks to participate in nuclear projects and technological collaborations.
**National Energy Grid & Government**
**Impact**
The expansion of nuclear power provides a stable, 24/7 low-carbon base load source, reducing reliance on carbon-intensive energy to meet 2070 net-zero targets.
**Action Required**
The government must ensure the timely execution of the Nuclear Energy Mission and maintain international cooperation agreements with the 18 partner countries already engaged.
Key Entities Referenced
India's Three-Stage Nuclear Power Programme: A long-term strategic framework designed to achieve energy independence by transitioning from uranium-based reactors to thorium-based energy systems.
The Sustainable Harnessing and Advancement of Nuclear Energy for Transforming India (SHANTI) Act, 2025: A legislative act that modernizes the nuclear legal framework and enables limited private sector participation and investment in India's nuclear sector.
Nuclear Energy Mission: A government initiative targeting 100 GW of nuclear power capacity by 2047, including a ₹20,000 crore allocation for Small Modular Reactors (SMRs).
Prototype Fast Breeder Reactor (PFBR): An indigenously designed 500 MWe reactor at Kalpakkam that signifies India's entry into the second stage of its nuclear power programme.
Department of Atomic Energy: The primary government department responsible for the scientific research, design, and implementation of India's nuclear energy policy.
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A New Chapter in India's Nuclear Journey
Posted On: 07 APR 2026 5:53PM by PIB Delhi
Indigenously built 500 MWe fast breeder reactor attains first criticality
Introduction
India has marked a major milestone in its nuclear energy programme. The indigenously designed and
built Prototype Fast Breeder Reactor (PFBR) at Kalpakkam in Tamil Nadu successfully attained its
first criticality on 6th April 2026, marking the initiation of a sustained nuclear chain reaction. This
PFBR is a 500 MWe (MegaWatt electrical) reactor built by Bharatiya Nabhikiya Vidyut Nigam Limited
(BHAVINI) at the Kalpakkam Nuclear Complex.
With this achievement, 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. The milestone carries substantial global significance. Once fully operational, India will
become only the second country in the world after Russia to operate a commercial fast breeder reactor.
This achievement is a testament to the decades of scientific effort led by the Department of Atomic
Energy. It also marks a significant step in India's clean energy journey, reinforcing the country's
commitment to reliable, low-carbon power. Additionally, it brings India closer to its goal of achieving net
zero emissions by 2070, as announced by Prime Minister Narendra Modi.
Overview of India's Three-Stage Nuclear Power ProgrammeIndia holds limited uranium reserves but one of the largest thorium reserves in the world. To make the
most of these resources, the Department of Atomic Energy designed a three-stage nuclear power
programme built 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 in PHWRs to generate power. The spent fuel from these reactors produces
plutonium, which becomes the primary input for the next stage.
Stage 2: Fast Breeder Reactors (FBRs)
The plutonium obtained from Stage 1 is used as fuel in Fast Breeder Reactors, which generate more fuel
than they consume. The PFBR at Kalpakkam marks India's entry into this stage. These reactors will be
used to breed Uranium-233 from thorium, laying the groundwork for Stage 3.
Stage 3: Thorium-Based Reactors
This stage will harness India's vast thorium reserves at scale, using the Uranium-233 bred in Stage 2 as
fuel. Thorium is considered a practically vast energy source and this stage holds 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: An Overview
The PFBR represents decades of indigenous research, design, and engineering. Its technology was
developed by the Indira Gandhi Centre for Atomic Research (IGCAR), an R&D centre under the
Department of Atomic Energy.
Fuel and Design: Unlike conventional thermal reactors, the PFBR uses Uranium-Plutonium Mixed
Oxide (MOX) fuel. The fissile material used is recovered from the reprocessing of spent fuel from
Pressurised Heavy Water Reactors, closing the loop on Stage 1.
Breeds More Than It Burns: The core of the PFBR is surrounded by a blanket of Uranium-238.
Fast neutrons convert this fertile material into fissile Plutonium-239, enabling the reactor to produce
more fuel than it consumes.
Bridge to Stage 3: The reactor is designed to eventually use Thorium-232 in the blanket. Through
transmutation, Thorium-232 will be converted into Uranium-233, the fuel that will power India's
third stage of nuclear energy based on thorium.
Closed Fuel Cycle: The spent fuel generated by the PFBR will be reprocessed and recycled back
into the reactor. This closes the second-stage fuel cycle and paves the way for large-scale use of
India's abundant thorium reserves in Stage 3.
Current Nuclear Power Landscape in India
India's nuclear energy programme has maintained a steady presence in the country's electricity mix. It now
stands at a pivotal moment, with significant expansion planned over the coming years.
Installed Capacity: India's current nuclear capacity is 8.78 Gigawatt (GW). In 2024–25, nuclear
power plants generated 56,681 Million Units of electricity across the country.
Stable Contribution: Nuclear power has consistently accounted for around 3% of India's total
electricity generation. In 2024–25, its share stood at 3.1%.
Planned Expansion: India's nuclear capacity is set to grow nearly 3x in the coming years. With
indigenous 700 Megawatt (MW) reactors and 1,000 MW reactors being developed through
international cooperation, the installed capacity is projected to reach 22.38 GW by 2031–32.International Cooperation: India has signed Inter-Governmental Agreements (IGAs) on Civil
Nuclear Cooperation for peaceful purposes with 18 countries, reflecting the growing global
confidence in India's nuclear programme.
Taken together, these numbers tell a clear story. Nuclear energy is no longer just a supplementary source
of power in India. It is fast becoming a cornerstone of the country's clean energy future.
Long-Term Mission
India has set its sights on a significantly larger role for nuclear energy in its overall power mix. The
Government has announced the Nuclear Energy Mission, outlined in the Union Budget 2025–26, with the
aim of achieving 100 GW of nuclear power generation capacity by 2047. The mission also supports India's
broader goal of achieving net zero carbon emissions by 2070.
Following measures have been put in place to drive this vision forward:
Financial Commitment: The Nuclear Energy Mission allocates Rs 20,000 crore towards the
design, development, and deployment of Small Modular Reactors (SMRs), signalling a serious
long-term investment in indigenous nuclear technology.
SMR Target: At least five indigenously designed SMRs are to be operational by 2033,
strengthening India's clean and reliable energy roadmap.
BARC Initiatives: The Bhabha Atomic Research Centre (BARC) is leading the development of
next-generation reactor designs, including the 200 MWe Bharat Small Modular Reactor (BSMR-
200), the 55 MWe SMR-55, and a High-Temperature Gas-Cooled Reactor of up to 5 MWth
(Megawatt thermal) designed for hydrogen generation.
SHANTI Act, 2025: To support the mission, the Government has enacted the ‘The Sustainable
Harnessing and Advancement of Nuclear Energy for Transforming India (SHANTI) Act,
2025.’ The Act consolidates and modernises India's nuclear legal framework. It enables limited
private participation in the nuclear sector under regulatory oversight, opening new avenues for
collaboration and investment.
India's long-term nuclear vision is ambitious by design. With policy backing, dedicated funding, and
indigenous research at its core, the country is building a nuclear future that is both self-reliant and globally
significant.
Conclusion
The attainment of criticality at the Prototype Fast Breeder Reactor marks more than a technological
milestone. It reflects the maturity of India’s long standing nuclear vision and the strength of its indigenous
capabilities. From limited uranium resources to a future powered by thorium, India’s three stage
programme is now moving steadily from design to delivery. The progress at Kalpakkam Nuclear Complex
signals confidence in advanced reactor technologies and reinforces the role of institutions such as
Department of Atomic Energy in driving this transformation. As capacity expands and new technologiestake shape, nuclear energy is set to play a far more central role in India’s energy mix. This moment
therefore stands as both an achievement and a turning point, strengthening the country’s pathway towards
energy security, technological self-reliance, and its net zero commitment for 2070.
References:
Department of Atomic Energy:
https://www.pib.gov.in/PressReleasePage.aspx?PRID=2249537®=3&lang=2
https://www.pib.gov.in/PressReleasePage.aspx?PRID=2205123®=3&lang=1
https://x.com/DAEIndia/status/2041204860314620133?s=20
PIB Backgrounders:
https://static.pib.gov.in/WriteReadData/specificdocs/documents/2025/dec/doc20251222741701.pdf
https://static.pib.gov.in/WriteReadData/specificdocs/documents/2024/sep/doc2024928403901.pdf
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