Snigdha Sharma and Rahel Philipose talking about how Thorium can help India’s energy needs in the Daybreak podcast.
[…] Homi Bhabha designed India’s long-term nuclear plan to work in a way that suits the country best. Here’s how he puts the idea behind the plan in his own words.
The total reserves of thorium in India amount to over 500,000 tonnes in the readily extractable form, while the known reserves of uranium are less than a tenth of this. The aim of a long-range atomic power program in India must therefore be to base the nuclear power generation as soon as possible on thorium rather than uranium. And the reason why he came up with a three-phase plan is because as Kalam explains in his quote, thorium by itself is not fissile.
[…] A fissile material is one that will undergo fission in a nuclear reactor. Fission is essentially a process where the atoms of a material split, and that splitting is what releases enormous amounts of energy.
Materials like uranium-235 and plutonium-239 are fissile, which is what makes them usable as reactor fuel directly. Thorium, on the other hand, is not fissile. Putting it in a reactor by itself does absolutely nothing.
What it is, though, is fertile. And that pretty much means exactly what you might think. It can be converted into a fissile material when it’s placed in or around a reactor that’s running on something else.
Then it can produce fuel that can then be used in the next generation of reactors. And that’s where the different stages come in. The first stage involves using pressurized heavy water reactors, or PHWRs, to generate electricity by burning natural uranium.
The by-product of this process is a spent fuel that contains plutonium-239. This stage is actually fully operational right now, with India running several of these reactors in Rajasthan, Karnataka, Maharashtra and Tamil Nadu. Now in stage 2, the plutonium by-product from stage 1 fuels a different kind of a reactor.
It’s called a fast-breeder reactor, which essentially breeds and creates more fissile material. During this stage, thorium is converted into uranium, and that is the uranium that can finally undergo fission in the last stage. And where are we with stage 2?
Well, there’s a single prototype fast-breeder reactor in Kalapakkam. It’s been in development for decades, and it’s the only stage 2 reactor we currently have. And it’s also supposed to be completed only by September this year, which brings us to the third and final stage.
This one involves yet another type of reactor, called an advanced heavy-water reactor. These are designed to run mainly on thorium, and once the process has begun, these reactors are designed to be self-sustaining. Which means the thorium in this reactor can basically just keep breeding more and more uranium.
But here’s the thing, we are still a long, long way off from stage 3. India has been leading the research on thorium-based nuclear power globally, and the kind of reactor that stage 3 needs has no precedent anywhere in the world. Mainly because all of this is a complex and expensive process, and to get to stage 3, you require a fully operational stage 2 that has been running for years and which has created the amount of uranium necessary to kickstart stage 3.
So while other countries found using uranium and plutonium easier and cheaper, thorium dropped as a priority for them. But India doesn’t have that same option. Like I mentioned earlier, the uranium reserves we have are miniscule, and we just can’t keep importing it forever.
For a long-term solution, thorium is the only option that makes sense. Because the Indian nuclear establishment has estimated that the country could produce 500 gigawatts of electricity for at least 4 centuries. And that’s just by using the country’s easily extractable thorium reserves.
500 gigawatts. 4 centuries. Wow. For context, India’s annual electricity generation for 2025-26 was 524 gigawatts. Do listen to the entire podcast, because it is not so straightforward as it appears.