Has India cracked its nuclear endgame?

In today’s episode on 16th April 2026, we talk about how India achieved criticality of its first ever Prototype Fast Breeder Reactor. Sign up for FREE insurance masterclass by Ditto https://ditto.sh/2cgegs

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  Hello folks, you're tuned into Finchart's Daily. In today's episode, we talk about how India achieved criticality of its first ever prototype fast breeder reactor.

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  But, here's a quick side note before we begin. This week, we're hosting a free two-day insurance masterclass that helps you build real financial security by understanding health and life insurance the right way. If you'd like to save your spot, then head to the link in the description and register while the seats last. By the way, it's completely free. Alright, let's get on to today's story. In the years after India gained independence, it was still finding its footing in the world, while one man was planning for decades ahead. Homi Jhaankir Baba wasn't just building a nuclear program. He was designing a future where India wouldn't depend on the world for its energy needs. But, there was a problem. India didn't have much uranium, the fuel most nuclear reactors run on.

• 0:54Speaker 00

  Even today, the country depends heavily on imports to keep its reactors running, including multi-billion dollar agreements with countries like Canada. What it did have, however, was something far less talked about. Vast reserves of thorium, or 25% of the global total, buried in its sands. There was just one catch though. Thorium by itself can't be directly used as fuel in most nuclear reactors. It needs to be converted into usable form, and that process requires another material to kickstart it. And, at the time, countries like the US were racing ahead with uranium-based reactors, scaling nuclear power as quickly as possible. Japan, on the other hand, would go on to build its program by importing both tech and fuel. India had neither luxury.

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  With limited uranium reserves, it couldn't simply replicate these models. So, instead of chasing speed, Baba chose something far more ambitious. A system that could turn this resource scarcity into self-reliance, even if it took decades to get there. It was a three-stage nuclear program that would begin with uranium, move to plutonium, and eventually unlock thorium as a long-term energy source. For context, stage one involves pressurized heavy water reactors, or PHWRs, which use natural uranium to generate electricity and produce plutonium. As a byproduct. Then comes stage two. Fast breed reactors which use that plutonium to generate more fuel than they consume. And finally, stage three.

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  Thorium-based reactors which use the bread material to unlock India's vast thorium reserves for long-term energy. For the longest time, it remained just that. A plan waiting to be completed because within this plan, that second stage remained the missing piece. That was until last week. On April 6th, India's prototype fast breeder reactor at Kalpakam, Tamil Nadu, achieved criticality for the first time. Criticality is the point where a nuclear reactor becomes self-sustaining. In other words, the change reaction inside the reactor continues on its own without needing any external push. On paper, this might sound like another technical milestone, but it isn't because fast breed reactors are new.

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  Russia has the only other commercial fast breed nuclear reactor in history, but this uses uranium instead of thorium. But in most other countries, the efforts behind these reactors haven't exactly gone as planned. These reactors are designed to do something unusual. They don't just generate power, they produce more nuclear fuel than they consume. Countries like the US, Japan and France have all tried building similar reactors using plutonium, but in practice, it was far more difficult. Japan's Monju reactor, for instance, was shut down back in 1995 after a sodium leak triggered a fire and eventually decommissioned years later. In the US, projects like the Clinch River Breeder Reactor were abandoned after costs went out of control.

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  Even France's Super Phoenix, which was one of the world's most ambitious breeder reactors, struggled with low use and was eventually shut down. Which is why over time, much of the world moved on to simpler nuclear designs or away from nuclear altogether. Things like running conventional reactors using uranium and securing long-term fuel supplies through domestic reserves or international partnerships. And yet, India didn't back down from this pursuit. It stayed committed to breeder reactors because they were essential. The stage was never just about generating electricity, it was about creating the materials for the third and the final stage. And that's what makes the PFVR milestone so significant. By achieving criticality, India has shown that it can run a reactor using plutonium-based fuel. This is a step that makes. Moving beyond uranium possible.

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  But more importantly, it brings the country closer to something far bigger. The ability to expand its nuclear fuel base. If fast breeder reactors work as intended, they can produce more usable, that is feasible materials than they consume, effectively turning a scarce resource into more usable fuel. In the process, they don't just create more fuel, they also make better use of what would otherwise be treated as nuclear waste. And that's what unlocks the final stage of the plan. Thorium, not as a fuel on its own, but as a material that can be turned into uranium-233. The fuel that powers a stage three. Here's a tricky part though, because getting it right wasn't just about switching a reactor on. To begin with, the reactor uses what's called MOX, that is mixed oxide fuel, which is a combination of plutonium and uranium.

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  This fuel had to be fabricated precisely, loaded into the reactor core and arranged in a way that would allow a controlled change reaction to begin. Unlike conventional reactors that use water as a coolant, the PFBR uses liquid sodium. This allows the reactors to operate at a much higher temperatures with fast-moving neutrons, both essential for breeding more fuel. But sodium comes with its own risks. It reacts violently with water and even air. So the entire cooling system has to be sealed, monitored and engineered with extreme precision. Even a minor leak could be dangerous. And then there's the moment of criticality itself. Achieving criticality is a gradual process. Control rods, which are used to absorb neutrons, are slowly withdrawn. Think of control rods like brakes. They absorb neutrons and keep the reaction in check.

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  As operators slowly pull them out, it's like easing off the brakes and the reaction starts picking up pace. Step by step, it builds until it reaches a point where it sustains itself. If it's too fast, you risk instability and if it's too slow, the reaction won't sustain. Everything has to be balanced perfectly. It took decades, but despite all these risks, they were able to achieve criticality and open the next stage for India's nuclear programme. Reaching criticality is just the beginning. Over the next few months, the plant will go through a series of control tests before it can begin fully commercial operations. Because achieving criticality proves the science, but it doesn't prove the economics. With an installed capacity of about 8.7 gigawatts, nuclear power accounts for just over Three percent of India's total electricity generation.

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  And that's quite small, especially when demand is only set to rise. If India wants to reduce its reliance on fossil fuel imports, mainly coal, and move towards energy independence, it needs more reliable sources of power. That's where nuclear comes in. It can complement intermittent renewables like solar and wind while providing steady 24 bar 7 base load power. For now though, nuclear energy occupies only a small slice of India's energy mix and there's still a long way to go. If this works, India can move beyond a single prototype to a fleet of breeder reactors and gradually reduce its dependence on imported uranium. And if that happens, India won't just be generating power. It'll be doing what Humi Baba envisioned decades ago. Running on fuel it already has, instead of relying on the world for it. Alright folks, I'll see you in the next one.

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  Thank you for listening to today's episode. And if you want to share your feedback or suggestions, do drop us an email to [email protected]. Until next time.