India has achieved a major milestone in nuclear energy. The 500 MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam has achieved PFBR 1st Criticality, marking the start of a self-sustaining nuclear chain reaction. The achievement is a significant step in India’s three-stage nuclear power programme and strengthens the country’s long-term energy security.
What Happened at Kalpakkam?
The PFBR achieved first criticality after years of design, construction, testing, and commissioning. Developed by IGCAR and built by BHAVINI, the reactor is located at Kalpakkam, Tamil Nadu. It is India’s first commercial-scale Fast Breeder Reactor.
What Does First Criticality Mean?
First criticality is the stage at which a reactor achieves a self-sustaining nuclear chain reaction. It confirms that the reactor core is functioning as designed. This is one of the most important milestones before electricity generation begins.
Why Is PFBR Unique?
PFBR is a Fast Breeder Reactor (FBR). Unlike conventional reactors, it can generate more fissile fuel than it consumes. This improves fuel utilization and supports long-term energy security. The reactor uses MOX fuel and liquid sodium coolant.
PFBR and India’s Three-Stage Nuclear Programme
India’s nuclear programme, envisioned by Dr. Homi J. Bhabha, follows a three-stage approach:
Stage 1 – Pressurized Heavy Water Reactors (PHWRs)
Stage 2 – Fast Breeder Reactors, including PFBR
Stage 3 – Thorium-based reactors
PFBR is a critical link between the second and third stages of the programme.
What Happens Next?
The reactor will undergo additional testing and power-raising operations. Following successful commissioning, it will begin commercial electricity generation. The experience gained will support future deployment of fast breeder reactors in India.
Why This Milestone Matters
- Strengthens India’s energy security
- Advances the three-stage nuclear programme
- Improves long-term fuel sustainability
- Demonstrates India’s advanced reactor capabilities
- Supports future nuclear capacity expansion
PFBR 1st Criticality is more than a reactor milestone. It marks India’s progress in advanced nuclear technology and its journey towards a secure and sustainable nuclear energy future.


