Thorium-Based Nuclear Power, The Key to Securing India’s Energy Independence
India’s nuclear strategy has long rested on a three-stage programme, built around a basic constraint: the country has limited uranium but vast reserves of thorium. In the first stage, pressurised heavy water reactors run on uranium to generate electricity and produce plutonium. The second stage uses this plutonium in fast breeder reactors to multiply fuel and prepare the ground for the final phase—thorium-based nuclear power, where thorium is converted into uranium-233 for long-term energy security.
This three-stage programme, conceived by Homi Bhabha, is India’s unique solution to its unique resource profile. While the world focuses on uranium, India has been patiently building the capability to unlock its thorium wealth.
The Opportunity from Scale
Former Atomic Energy Commission chairman Anil Kakodkar, a towering figure in India’s nuclear establishment, now sees a significant opportunity to accelerate this transition. With a large PHWR capacity now running on imported uranium, India can start producing uranium-233 by irradiating thorium alongside advanced fuels such as HALEU (High-Assay Low-Enriched Uranium), accelerating the country’s path to energy independence.
Transitioning to thorium-based nuclear power generation is critical to securing energy independence. This requires building sufficient inventory of fissile U233 through irradiation of thorium. Since our assessed domestic uranium resources when the three-stage programme was formulated were modest, the required irradiation capacity was not possible. Building such capacity through fast reactors, which can multiply through breeding of fissile fuel, was thus essential.
Now that we can access uranium from the international market, the thermal reactor capacity is on a growth path, with the Nuclear Energy Mission targeting 100 GW nuclear power capacity, with PHWRs constituting the bulk. This scale-up is clearly an opportunity to start producing fissile U233 at scale in PHWRs and enable a faster transition to thorium-based nuclear power generation.
It is indeed possible to have Thorium-HALEU based drop-in fuel for PHWRs, which would also lead to economic, safety and security benefits while efficiently converting thorium to U233.
The Scale-Up Challenge
Scaling up PHWR capacity to 50-75 GW by the target date of 2047 would require an average annual capacity addition of around 3 GW, which would mean adding five to eight reactors every year depending on the mix of 700 MW and 220 MW units. This is an ambitious target by any measure.
This would require significant additional financial resources. Also, one would need many other players from public as well as private sector to be brought in, with NPCIL (state-owned Nuclear Power Corporation of India Ltd.) playing the role of technology provider, capacity builder, facilitator and mentor while implementing its own programme.
The model is one of partnership, not privatisation. NPCIL retains its central role but expands the ecosystem by bringing in new players. This is how industries scale.
The Role of Imported Reactors
I have always viewed imported Light Water Reactors as an additionality. Given our large and growing energy needs, and deficit in our implementation capability, such additionalities are helpful provided they are economically competitive and consistent with our nuclear fuel cycle policies.
We should prioritise development effort for futuristic technologies needed for our country (metal fuel reactors, molten salt reactors, high temperature reactors, thorium fuel cycles etc) and leverage proven imported technologies.
This is a sensible strategy: build indigenous capability in next-generation technologies while using imports to meet immediate needs. The SHANTI Act opens up the possibility of more imported LWR-based nuclear projects, which can supplement domestic capacity.
The Economics of Fuel
Estimates suggest that a 1,000 MW-LWR would need about 25 tonnes of enriched fuel per year at 80% PLF. Given the fuel price of around $1.76 million per tonne, the fuel cost for an LWR plant would translate to around Rs 350 crore per annum. Fuel estimates for PHWRs would perhaps be lower.
In terms of mined uranium needed to support a given nuclear power generation capacity, PHWRs are more efficient. Fuel fabrication and back-end fuel cycle costs in PHWRs fueled with natural uranium would be higher on account of higher fuel throughput as the burn-up is low. These costs would come down with the use of enrichment in PHWR fuel.
Fueling cost with HALEU-thorium fuel in PHWR works out to be lower than with natural uranium. This is a significant finding. The combination of thorium and enriched uranium is not just strategically advantageous; it is economically competitive.
The Strategic Imperative
India’s thorium reserves are among the largest in the world. Successfully unlocking this resource would give India a degree of energy independence that few countries can match. It would reduce dependence on imported uranium and insulate the country from global market fluctuations.
But thorium is not a fuel in itself; it must be converted to fissile U233 through irradiation. This requires reactors, fuel cycles, and the entire nuclear infrastructure. The three-stage programme was designed to create this capability over decades. The current scale-up of PHWR capacity, fuelled by imported uranium, provides an opportunity to accelerate the timeline.
Conclusion: A Vision for Energy Independence
Anil Kakodkar’s vision is clear: use the current expansion of nuclear capacity, enabled by imported uranium, to build the inventory of U233 needed for thorium-based reactors. Involve private players to scale up manufacturing. Import LWRs where needed, but focus indigenous effort on next-generation technologies. And design fuel cycles that are not just strategic but economic.
If this vision is realised, India could achieve true energy independence by the middle of the century. Thorium, once a distant promise, could become a present reality. The three-stage programme, conceived decades ago, would reach its final culmination.
The path is clear. The technology is proven. The resources are available. What remains is the will to execute.
Q&A: Unpacking India’s Thorium Strategy
Q1: What is India’s three-stage nuclear programme?
Stage 1: Pressurised heavy water reactors (PHWRs) run on uranium to generate electricity and produce plutonium. Stage 2: Fast breeder reactors use this plutonium to multiply fuel. Stage 3: Thorium-based reactors use uranium-233 (converted from thorium) for long-term energy security. This programme leverages India’s limited uranium and vast thorium reserves.
Q2: How does imported uranium help accelerate thorium adoption?
With access to international uranium, India can scale up PHWR capacity faster. This creates more reactors that can irradiate thorium alongside advanced fuels like HALEU to produce fissile uranium-233. Previously, limited domestic uranium constrained the irradiation capacity needed to build U233 inventory.
Q3: What is the scale-up target and challenge?
India aims for 50-75 GW of PHWR capacity by 2047, requiring average annual addition of about 3 GW (5-8 reactors yearly). This demands significant financial resources and involvement of multiple players beyond NPCIL, with NPCIL acting as technology provider and mentor. Private sector participation will be crucial.
Q4: What is the role of imported Light Water Reactors?
Kakodkar views imported LWRs as “additionality”—helpful to meet growing energy needs provided they are economically competitive and consistent with India’s fuel cycle policies. The SHANTI Act enables more such projects. However, indigenous effort should focus on futuristic technologies (metal fuel, molten salt, high temperature reactors).
Q5: How does the economics of HALEU-thorium fuel compare?
PHWRs are more uranium-efficient than LWRs. While natural uranium PHWR fuel has higher fabrication costs due to low burn-up, using enrichment (HALEU-thorium) reduces these costs. Fueling cost with HALEU-thorium works out lower than natural uranium, making the strategic option economically competitive.
