Thorium Strategy Gains Focus in India’s 100 GWe Nuclear Power Roadmap

Why in News ?

The recently proposed SHANTI Act 2025 aims to expand India’s nuclear energy sector by allowing wider participation from public and private players, academia, and industry, while strengthening the regulatory ecosystem.

At the same time, India’s ambitious plan to achieve 100 GWe nuclear power capacity by 2047 faces a major challenge : limited domestic uranium reserves. Achieving this capacity may require 18,000–20,000 tonnes of uranium annually, which would largely depend on imports.

This has renewed policy attention on thorium-based nuclear fuel cycles, where India possesses some of the largest reserves in the world.

Background and Context

Nuclear power is expected to remain a reliable low-carbon energy source in the coming decades, especially as countries aim to reduce dependence on fossil fuels.

However, conventional nuclear power largely relies on uranium-based fuel cycles, which pose long-term sustainability concerns due to :

• Limited global uranium reserves
• Rising global demand for nuclear fuel
• Strategic vulnerabilities linked to import dependence

In this context, India’s long-standing nuclear strategy—designed by Homi Jehangir Bhabha — focuses on utilising abundant thorium reserves to ensure long-term energy security.

Thorium as a Solution to Uranium Constraints

Thorium offers a potential alternative to uranium-based nuclear fuel cycles.

Unlike uranium, thorium itself is not directly fissile, but it can be converted into uranium-233, a fissile material capable of sustaining nuclear reactions.

Advantages of Thorium-Based Fuel

• Abundant availability in India
• Greater long-term energy security
• Lower risk of nuclear weapons proliferation
• Higher fuel utilisation efficiency

Through nuclear fuel recycling, the energy extracted from nuclear fuel can increase 50–100 times compared to once-through cycles, improving resource efficiency.

India’s Three-Stage Nuclear Power Programme

India’s nuclear strategy is structured around a three-stage programme designed to gradually transition toward thorium-based energy generation.

Stage I – Pressurised Heavy Water Reactors (PHWRs)

The first stage relies on Pressurised Heavy Water Reactor technology.

Fuel : Natural uranium (U-238)

Key Process

• Uranium is used to generate electricity.
• The reactor also produces plutonium-239 as a byproduct, which becomes fuel for the next stage.

PHWRs currently form the backbone of India’s nuclear power generation.

Stage II – Fast Breeder Reactors

The second stage involves Fast Breeder Reactor (FBRs).

Fuel : Plutonium-239 and uranium-238.

Key Role

FBRs breed more fissile material than they consume, generating the fuel inventory needed for the third stage.

India’s 500 MWe Prototype Fast Breeder Reactor (PFBR) is nearing completion and is a crucial step toward scaling this technology.

Stage III – Thorium-Based Reactors

The final stage aims to fully utilise thorium.

Fuel : Thorium-232 and plutonium-239.

Process

Thorium-232 is converted into uranium-233, which then acts as the fissile fuel for electricity generation.

This stage is designed to enable long-term sustainable nuclear power generation in India.

Role of Fast Breeder Reactors

Fast breeder reactors are essential for producing the fissile materials required for thorium utilisation.

They help :

• Generate uranium-233 from thorium
• Expand the fissile fuel inventory
• Enable large-scale deployment of thorium-based reactors

However, widespread deployment of FBRs is expected only in the coming decades, as the technology is complex and capital-intensive.

Expanding PHWR Capacity and the 100 GWe Target

India’s immediate nuclear expansion strategy focuses largely on Pressurised Heavy Water Reactors.

These reactors :

• Use natural or imported uranium fuel
• Are technologically mature
• Can be deployed relatively quickly

At the same time, PHWRs could be used to irradiate thorium, helping generate uranium-233 earlier and accelerating the transition to the third stage.

HALEU–Thorium Fuel Pathway

Another emerging pathway involves combining thorium with High-Assay Low-Enriched Uranium (HALEU).

Advantages

• Higher fuel burnup
• Reduced nuclear waste
• Improved reactor safety
• Lower spent fuel management costs

However, India currently lacks adequate irradiation testing facilities for such advanced fuels. International collaboration could accelerate technology development.

Emerging Technologies: SMRs and Advanced Reactors

India is also exploring advanced nuclear technologies such as :

Small Modular Reactors

Small Modular Reactor (SMRs) offer :

• Lower construction costs
• Modular deployment
• Enhanced safety systems

These reactors could also support green hydrogen production, contributing to the clean energy transition.

Thorium Molten Salt Reactors

India is researching Thorium Molten Salt Reactors (TMSRs) that can :

• Use thorium efficiently
• Operate at higher safety levels
• Reduce long-term radioactive waste

Significance for India

1. Energy Security

Thorium utilisation can significantly reduce dependence on imported uranium, strengthening India’s strategic autonomy.

2. Clean Energy Transition

Nuclear energy provides stable low-carbon power, helping India meet climate commitments.

3. Technological Leadership

India’s expertise in thorium fuel cycles could make it a global leader in advanced nuclear technology.

4. Long-Term Sustainability

Thorium reserves can potentially sustain India’s energy needs for centuries, ensuring long-term power security.

Way Forward

To realise the 100 GWe nuclear power vision by 2047, India needs to :

• Accelerate deployment of fast breeder reactors
• Expand PHWR capacity
• Develop advanced thorium reactors
• Promote public-private collaboration under the SHANTI Act
• Strengthen international nuclear research partnerships

Such measures can help India move toward energy independence and sustainable nuclear power generation.