07-January-2025-Editorial

WHAT IS A THORIUM REACTOR: NEXT-GENERATION NUCLEAR POWER

India is making significant strides in nuclear energy development by leveraging its vast thorium resources. The National Thermal Power Corporation (NTPC) Limited, India’s largest power producer, has partnered with Clean Core Thorium Energy (CCTE), a US-based firm, to explore advanced nuclear energy solutions using thorium-based fuel known as Advanced Nuclear Energy for Enriched Life (ANEEL).

What is ANEEL?

• ANEEL stands for Advanced Nuclear Energy for Enriched Life.
• It is a patented nuclear fuel combining thorium and High Assay Low Enriched Uranium (HALEU).
• The fuel honors Dr. Anil Kakodkar, a prominent Indian nuclear scientist.

What is HALEU?

• HALEU is uranium enriched between 5% and 20%, which is crucial for advanced nuclear reactor designs.
• Currently, HALEU is mainly produced in Russia and China, with limited production in the US.

Compatibility with PHWRs:

• ANEEL fuel can be used in existing Pressurized Heavy Water Reactors (PHWRs), which form the backbone of India’s nuclear fleet.
• India currently has 22 operational reactors, including 18 PHWRs.
• India is constructing 10 more PHWRs, each with a capacity of 700 MW.

Ease of Thorium Deployment

• ANEEL provides a quicker and simpler method for deploying thorium, utilizing imported HALEU, as opposed to India’s traditional, more time-consuming method of creating thorium blankets around uranium or plutonium reactors.

Benefits of ANEEL Fuel

Efficiency:

• ANEEL fuel has a burn-up efficiency of 60,000 MW-days per tonne, significantly higher than the 7,000 MW-days per tonne of conventional uranium.
• This reduction in the number of fuel bundles needed can cut operational costs and waste volumes considerably.

Non-Proliferation:

• Thorium and the spent ANEEL fuel are non-weaponizable, which reduces proliferation concerns, especially among foreign uranium suppliers and reactor operators.

Economic and Environmental Impact:

• The higher efficiency of ANEEL fuel leads to reduced operating costs and longer-lasting fuel bundles.
• ANEEL aligns with India’s clean energy goals and global efforts to triple nuclear energy capacity, as discussed at COP28 in Dubai.

Global Collaboration:

• The innovative blend of HALEU and thorium has attracted global attention.
• Canadian Nuclear Laboratories (CNL) has signed a Memorandum of Understanding (MoU) with CCTE to advance research and licensing for ANEEL fuel.

Thorium: An Important Resource

Thorium is a naturally occurring, slightly radioactive metal found in igneous rocks and mineral sands.

Abundance:

• Thorium is three times more abundant than uranium, with a concentration of 10.5 parts per million (ppm), compared to uranium’s 3 ppm.

Fissile vs. Fissionable:

• Thorium-232 is fissionable, meaning it can undergo fission but is not naturally fissile (it cannot sustain a chain reaction on its own).
• It requires high-energy neutrons to initiate fission.

Thorium-Based Nuclear Reactors

What is a Thorium-Based Nuclear Reactor?

• A thorium-based reactor uses thorium-232 as the primary fuel, unlike traditional reactors that use uranium-235 or plutonium-239.
• Since thorium is a fertile material, it must be paired with a fissile material, such as uranium-233, uranium-235, or plutonium-239, to sustain a nuclear reaction.

Fuel Cycle Strategies:

• Thorium with Low Enriched Uranium (LEU): LEU, enriched with 19.75% uranium-235, is mixed with thorium to form Thorium-LEU Mixed Oxide (MOX) fuel.
• Thorium with Plutonium: This configuration uses plutonium as an external fissile material.

Advantages of Thorium-Based Reactors

• Reduced Nuclear Waste: Thorium-based reactors generate fewer long-lived minor actinides, which are harmful radioactive elements, compared to uranium-plutonium reactors.
• Safety: The presence of uranium-232 in spent thorium fuel produces hard gamma radiation, which makes the fuel less attractive for weaponization.
• Recycling Potential: Thorium allows for multiple recycling cycles, improving fuel efficiency by reducing non-fissile absorption in uranium-233.
• Enhanced Fuel Utilization: In water-cooled or molten-salt reactors, thorium can generate more fissile uranium-233 than it consumes, making it highly efficient.

Challenges in Thorium Reactors

• Extraction Costs: Extracting thorium can be expensive because it is a by-product of monazite mining, which is primarily driven by the demand for rare earth metals.
• Dependence on Fissile Drivers: Thorium requires an external fissile material, such as uranium-235 or plutonium-239, to initiate and sustain the nuclear reaction.
• Limited Experience: Most nuclear systems are designed for uranium, so there is limited research and operational experience with thorium-based reactors.

India’s Three-Stage Nuclear Power Program

India’s three-stage nuclear program aims to make efficient use of its uranium resources while tapping into the country’s vast thorium reserves.

It was developed by Dr. Homi Bhabha to ensure energy security and self-reliance.

The Three Stages:

• Stage I: Involves setting up PHWRs that use natural uranium (U-238) as fuel and heavy water as a moderator and coolant. The spent fuel is then reprocessed to obtain plutonium.
• Stage II: Utilizes Fast Breeder Reactors (FBRs) fueled by plutonium and uranium-233 bred from thorium.
• Stage III: Focuses on using thorium-based reactors with uranium-233 as the primary nuclear fuel.

The Prototype Fast Breeder Reactor (PFBR):

The operationalization of the PFBR marks the beginning of Stage II, and it is currently being developed at the Madras Atomic Power Station in Kalpakkam, Tamil Nadu.

Conclusion:

India’s nuclear energy strategy, anchored in the three-stage program, aims to capitalize on thorium to ensure long-term energy sustainability. The collaboration with CCTE for advanced thorium fuel (ANEEL) offers an efficient, low-waste solution for the country’s energy needs. Although there are challenges to overcome, thorium’s potential for India’s future energy security remains significant.