India's Kalpakkam reactor goes critical: A leap into the nuclear future

India on Monday achieved a major milestone in its civil nuclear programme, with the Prototype Fast Breeder Reactor (PFBR) at Kalpakkam in Tamil Nadu attaining “criticality”. External Affairs Minister S Jaishankar called the development a “historic milestone”, highlighting its importance for India’s energy independence and technological progress.

The reactor reached this stage on April 6, marking a crucial step before it begins full power generation. Prime Minister Narendra Modi described this achievement as a “defining step” in India’s nuclear journey, underlining the country’s scientific and engineering capabilities.

The PFBR is India’s most advanced nuclear reactor so far and has been developed largely using domestic expertise.

What ‘criticality’ means?

In simple terms, criticality is the point at which a nuclear reactor achieves a self-sustaining chain reaction. This means that Plutonium that is being fed into fast breeder reactors, would breed more Plutonium by itself, without any external support.

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Reaching criticality does not mean that the reactor has become fully operational. It is an important milestone that comes before the power generation finally begins. In simple terms, though the electricity is not yet flowing, the biggest technical hurdle has been cleared.

Why this reactor is important?

The PFBR is a 500 megawatt electric (MWe) reactor and is part of India’s three-stage nuclear power programme. The latest development represents the second stage of this long-term strategy.

The unique characteristic of this reactor is its ability to produce more fuel than it consumes. Known as a “breeder reactor”, it uses plutonium-based fuel and can generate additional fissile material for future input use.

This is particularly important for India, as the country has limited Uranium reserves, but abundant Thorium reserves. It is expected that the PFBR will play a key role in using thorium as a major energy source (in the third stage of the nuclear programme.)

Explaining the significance of this major development, Prof Ashok Kumar, working at Delhi University's Department of Physics and Astrophysics told Firstpost that India cannot remain dependent on Uranium, as it has its limited reserves.

"Also India faced major restrictions in Uranium import, especially during Kargil war. So, it is vital for India to effectively use its Thorium in nuclear power generation. In this regard, Kalpakkam achieving criticality is a major development in India's nuclear journey," he said.

Boost to self-reliance

The Kalpakkam reactor has been designed and built in India, showcasing the country’s indigenous capabilities in complex nuclear technology.

Experts say this achievement places India among a select group of countries that have developed fast breeder reactor technology at this scale. People on social media platforms have also celebrated this critical nuclear achievement of India.

Nuclear researcher Nick Touran termed this a 'great accomplishment' for India, highlighting that how even the United States failed to develop the Breeder technology.

The PFBR has been in development for over two decades and is now close to becoming fully operational. Once commissioned, it is expected to significantly contribute to India’s electricity generation and clean energy goals.