**Executive Summary**
On April 6, 2026, at 08:25 PM, India’s 500 MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam attained first criticality, marking a milestone in the nation’s three-stage nuclear power programme. Developed indigenously by IGCAR and BHAVINI, the project received safety clearance from the Atomic Energy Regulatory Board (AERB) after a rigorous review. This achievement is a key step toward long-term energy security and the future deployment of thorium-based reactors.
**Key Points / Main Content**
* **Project Overview and Milestone**
* The PFBR is a 500 MWe reactor that has successfully started its controlled fission chain reaction (criticality).
* The project was indigenously designed by the Indira Gandhi Centre for Atomic Research (IGCAR) and built by Bharatiya Nabhikiya Vidyut Nigam Ltd (BHAVINI).
* The milestone was achieved following strict adherence to safety stipulations set by the Atomic Energy Regulatory Board (AERB).
* **Technical Specifications**
* The reactor uses Uranium-Plutonium Mixed Oxide (MOX) fuel.
* It features a Uranium-238 blanket that converts to fissile Plutonium-239, producing more fuel than it consumes.
* The design incorporates high-temperature liquid sodium coolant and advanced safety systems.
* It utilizes a closed fuel cycle approach to enable the recycling of nuclear materials and reduce waste.
* **Strategic Objectives**
* The PFBR serves as a bridge between pressurized heavy water reactors and the third stage of India’s nuclear programme, which will use Thorium-232.
* The reactor is designed to eventually transmute Thorium-232 into Uranium-233 for future clean energy generation.
* The project strengthens India's "Atmanirbhar Bharat" goals by using predominantly indigenous technologies and components.
**Impact Analysis**
**Department of Atomic Energy (DAE) / Government of India**
**Impact**
The achievement moves the country closer to realizing its three-stage nuclear power programme and enhances the strategic utilization of limited uranium reserves.
**Action Required**
Continue to oversee the integration of this technology into the national grid and support the transition toward the thorium-based third stage.
**BHAVINI and IGCAR**
**Impact**
These organizations have successfully demonstrated expertise in advanced nuclear engineering, large-scale engineering, and indigenous manufacturing.
**Action Required**
Leverage the infrastructure and knowledge gained from this project to support next-generation nuclear technologies and future reactor designs.
**Atomic Energy Regulatory Board (AERB)**
**Impact**
The successful attainment of criticality validates the AERB’s rigorous safety review and regulatory oversight of the plant's systems.
**Action Required**
Maintain ongoing regulatory surveillance and safety monitoring as the reactor moves from first criticality to full-scale power generation.
Key Entities Referenced
Prototype Fast Breeder Reactor (PFBR), Kalpakkam, Tamil Nadu: A 500 MWe indigenously designed reactor that attained first criticality, serving as a vital bridge to the third stage of India's nuclear power programme.
India’s three-stage nuclear power programme: A long-term strategic framework aimed at utilizing the country's thorium resources for sustainable and self-reliant nuclear energy generation.
Bharatiya Nabhikiya Vidyut Nigam Ltd (BHAVINI): The Public Sector Undertaking under the Department of Atomic Energy responsible for building and commissioning the PFBR.
Indira Gandhi Centre for Atomic Research (IGCAR): The R&D center of the Department of Atomic Energy that indigenously developed the technology and design for the Prototype Fast Breeder Reactor.
Atomic Energy Regulatory Board (AERB): The regulatory body that issued the safety clearance for the PFBR after a rigorous review of the plant’s systems and safety stipulations.
Department of Atomic Energy
Prototype Fast Breeder Reactor at Kalpakkam,
Tamil Nadu attains First Criticality
Posted On: 07 APR 2026 11:17AM by PIB Delhi
In a landmark achievement for India’s nuclear energy programme, the 500 MWe Prototype Fast Breeder
Reactor (PFBR) has successfully attained first criticality (start of controlled fission chain reaction) on 6th
April 2026 at 08:25 PM marking a historic step in providing long-term energy security and advancing
indigenous nuclear technology capabilities.
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 after meeting all the
stipulations of the Atomic Energy Regulatory Board (AERB), which had issued clearance after a rigorous
review of safety of the plant systems.
The technology development & design of PFBR was indigenously done by Indira Gandhi Centre for
Atomic Research (IGCAR), an R&D Centre of the Department of Atomic Energy, and was built &
commissioned by Bharatiya Nabhikiya Vidyut Nigam Ltd (BHAVINI), a PSU under the Department of
Atomic Energy.
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.
This unique capability significantly enhances the utilization of nuclear fuel resources and enables the
country to extract far greater energy from its limited uranium reserves while also preparing for large-scale
use of thorium in the future.
With the achievement of first criticality, India moves closer to realizing the full potential of its three-stage
nuclear power programme. Fast breeder technology forms the vital bridge between the current fleet of
pressurized heavy water reactors and the future deployment of thorium-based reactors, leveraging the
country’s abundant thorium resources for long-term clean energy generation.
Achieving this milestone demonstrates the strength of India’s indigenous design, engineering and
manufacturing ecosystem. The reactor incorporates advanced safety systems, high-temperature liquid
sodium coolant technology and a closed fuel cycle approach that enables recycling of nuclear materials,
thereby improving sustainability and reducing waste.
The project also reflects the dedication of significant number of scientists, engineers, technicians and
industry partners who have contributed to the design, fabrication and construction of the reactor using
predominantly indigenous technologies and components. Their efforts highlight the nation’s growingcapability in advanced nuclear engineering and reinforce India’s commitment to technological self-
reliance complying with Atmanirbhar Bharat.
Beyond energy generation, the fast breeder programme strengthens strategic capabilities in nuclear fuel
cycle technologies, advanced materials, reactor physics and large-scale engineering. The knowledge and
infrastructure developed through this programme will support future reactor designs and next-generation
nuclear technologies.
As India continues to expand its clean energy portfolio, fast breeder reactors will play a crucial role in
delivering reliable, low-carbon, base-load power with higher thermal efficiency. The attainment of first
criticality represents not only a technological milestone but also a major step towards a sustainable and
self-reliant energy future for Viksit Bharat.*****
NKR/AK
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