BT Explainer: Why Reliance, Adani are banking on nuclear fusion reactors over thorium

During the same time India's first prototype fast breeder (FBR) reactor achieved criticality, Bengaluru-based startup Pranos raised $6.8 million in seed funding to build India's first commercial fusion reactor prototype.  

It may not have caught eyeballs compared to India’s formal entry into Stage 2 of the three-stage nuclear programme with FBR, but fusion-based power could come online way before the thorium based rectors to meet the country’s energy needs.

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Indian top conglomerates Reliance and Adani have held discussions on investments in the future technology that neither requires uranium or plutonium as fuel nor creates long-lived radioactive waste, making it a cleaner and safer alternative to nuclear fission reactors in India.    

Why fusion based rectors?

Indian top conglomerates Reliance and Adani have held discussions on investments in the future technology that neither requires uranium/plutonium as fuel nor creates long-lived radioactive waste, making it a cleaner and safer alternative to nuclear fission reactors in India.    

Must Read: BT EXPLAINER: Kalpakkam fast breeder reactor goes critical: What it means

India doesn’t have uranium reserves and imports all from other countries to run its existing nuclear reactors. Despite high thorium reserves, it will take two to three decades for the deployment of Stage 3 reactors.

Thorium-based reactors require an initial loading of ²³³U -- a material that does not occur in nature and must be bred from thorium by bombarding it with neutrons. The only source of those neutrons at scale is the FBR fleet. But FBRs take decades to build, and their early fuel is precious Pu-239 from Stage 1 — itself in limited supply.  

Fusion-based reactor technology is gaining traction with a couple of Indian start-ups looking at power generation by 2035, while thorium-based reactors are a few decades away.

Pranos, Anubal Fusion, Hylenr Technologies and ASPL Fusion are key players looking to make India energy independent using this yet-to-be-proven commercial energy source.

The most common form of fusion reaction occurs in stars and the sun. India has fission-based reactors, where when you split a larger atom (Uranium) into several smaller atoms, high energy is released in the form of heat. Fusion is the opposite of fission - you combine two smaller atoms to form a larger atom, and in the process, release energy that is exponentially higher than fission.

Looking at tapping all possible sources of clean energy to meet India’s growing power demand, the Central Electricity Authority (CEA) in January this year constituted a committee for the preparation of a roadmap for the deployment of nuclear fusion-based power generation in the country.

India is already contributing Rs 745 crore in 2026-27 for a global fusion project, the International Thermonuclear Experimental Reactor (ITER), a multi-country endeavour located in France. Prime Minister Narendra Modi had in February 2025 visited the site in Marseille, France.

India’s fusion progress?

Pranos, Anubal Fusion, Hylenr Technologies and ASPL Fusion started working on fusion technology after 2024. The good part, all of them are working on different technologies to make a breakthrough in the commercial deployment of fusion-based power reactors.

“The reason being in 2022, the “National Ignition Facility” at Lawrence Livermore National Laboratory in the US successfully demonstrated Fusion Ignition (generating more energy output than input) for the first time in history. Since then, the race to fusion has significantly heated up with over 40+ private companies,” explains Nithish Kumar, Investment Analyst at Speciale Invest. The deep tech VC fund invested in Anubal Fusion in 2024.   

Gandhinagar-based ASPL fusion, one of the youngest startups in the group, looks at a fusion-fission hybrid technology. It came up after the passing of the Sustainable Harnessing and Advancement of Nuclear Energy for Transforming India Act, 2025. 

“India’s PFBR at Kalpakkam achieved first criticality, entering Stage 2 of the three-stage nuclear programme. But Stage 3, the thorium endgame, remains 45-65 years away. The bottleneck is ²³³U, which must be bred from thorium and currently depends entirely on the slow FBR build-out. Fusion-fission hybrid technology offers a parallel route: fusion neutrons driving a subcritical thorium blanket, independently of the FBR fleet, potentially compressing the wait by 20–30 years,” says Dr Prabhat Ranjan, Co-founder of ASPL fusion.

Ranjan also chairs the CEA committee, having members from NTPC, Niti Aayog, Department of Atomic Energy (DAE) and Hylenr technologies. It is likely to submit its report in the next few weeks.  

Why is fusion gaining traction globally?

Globally, several countries are pursuing fusion-based reactors as future clean energy sources.  According to the Fusion Industry Association 2025 Global Fusion Industry Report, more than $2.5bn has been invested in the fusion energy industry in the past year.

As many as 35 companies are aiming to operate a commercially viable pilot plant between 2030 and 2035, and the last five years’ trend professes fusion’s potential as a commercially viable and scalable clean energy solution.

The commercial deployment of nuclear fusion reactors is being looked at around the end of this decade. China plans to start construction of the world’s first fusion-fission power plant, with the aim of generating 100 MW of continuous electricity for the national grid by 2030. The facility is to be built on Yaohu Science Island in the hi-tech zone of Nanchang, Jiangxi province, in central China, according to reports.

To enhance the focus on fusion energy research, the US Department of Energy (DOE) announced in October 2024  that it will provide $49 million in funding for 19 projects in its Fusion Energy Sciences (FES) program, which include foundational fusion materials, nuclear science, heating technology, magnet technology, blankets, fuel cycles, and first wall research.