India’s largest power producer, National Thermal Power Corporation (NTPC) Limited has signed a strategic agreement with US-based Clean Core Thorium Energy (CCTE) to explore development and deployment of Advanced Nuclear Energy for Enriched Lives (ANEEL) thorium based fuel. ANEEL developed by CCTE is a thorium based fuel for Pressurised Heavy Water Reactors (PHWR). The Department of Atomic Energy (DAE) plans to utilise India’s abundant thorium reserves in its three-stage nuclear power programme as a long-term strategy.
Advanced Nuclear Energy for Enriched Life
- ANEEL is a patented nuclear fuel which is a mixture of thorium and High Assay Low Enriched Uranium (HALEU). The fuel is named in honour of Dr. Anil Kakodkar, one of India’s leading nuclear scientists.HALEU is uranium enriched from 5% to 20%, which is required for many advanced nuclear reactor designs. It is currently produced only in Russia and China, and its production in the US is limited.
- Compatibility with PHWR: ANEEL fuel can be used in existing PHWRs, which are the source of India’s nuclear power. Currently, India has 22 reactors in operation, with an installed capacity of 6780 MW. Of these, 18 reactors are PHWRs and 4 are Heavy Water Reactors (LWRs). India is constructing 10 more PHWRs, each of which will have a capacity of 700 MW.
- Ease of thorium deployment: Using imported HALEU, ANEEL offers a simpler and faster option for thorium deployment. India’s traditional method of producing uranium-233 is labour-intensive and involves the use of thorium around uranium or plutonium reactors.
Benefits
- Efficiency: ANEEL fuel has a burn-up efficiency of 60,000 megawatt-days per tonne, compared to 7,000 megawatt-days per tonne for conventional natural uranium. By reducing the required lifetime of fuel bundles in a typical 220 MW PHWR from 1,75,000 to 22,000, ANEEL substantially reduces the amount of fuel waste and operating expenses.
- Non-proliferation: Thorium and spent ANEEL fuel are non-weaponizable, reducing proliferation concerns for foreign uranium suppliers and reactor operators.
- Economic and environmental impact: ANEEL fuel reduces the operating cost of reactors due to its high efficiency and long-lasting fuel bundles. This is in line with India’s clean energy goals and global commitment to triple nuclear capacity, as highlighted during COP28 in Dubai, UAE.
- Global collaboration: The HALEU-thorium blend in ANEEL has attracted global attention ever since Canadian Nuclear Laboratories and CCTE signed a MoU to promote ANEEL fuel development and licensing.
Thorium
- Thorium is a silvery, radioactive metal. It is commonly found in igneous rocks and heavy mineral sands.
- Abundance: Thorium is three times more abundant than uranium at the Earth’s surface, with an average concentration of 10.5 parts per million (ppm) compared to about 3 ppm for uranium.
- Fissionable but not fissile: The only naturally occurring isotope of thorium is thorium-232, which is fissionable (can fission) but not fissile (cannot continue the chain reaction without an external neutron).Thorium-232 requires a high-energy neutron to fission.
Thorium-based nuclear reactors
- Thorium-based nuclear reactors: These use thorium-232 as the primary fuel instead of uranium-235 or plutonium-239. Thorium is not a fissile material but a fertile material, which means that it must be combined with uranium-235 or plutonium-239 to be used as a nuclear fuel. Thorium must be used with fissile material such as 233U, 235U or 239Pu to initiate and sustain a nuclear reaction.
Fuel cycle strategies
- Thorium with low enriched uranium (LEU): LEU has a 235U enrichment of 19.75% and is combined with thorium to form thorium-LEU mixed oxide (M.O.X.) fuel.
- Thorium with Plutonium (Pu): This configuration uses plutonium as an external fissile stock.
Advantages
- Reduction of nuclear waste: Thorium-based reactors produce significantly less long-lived short actinides (elements that emit ionizing radiation) than uranium-plutonium fuel cycles.
- Safety: The presence of 232U in spent fuel produces hard gamma radiation, which deters weaponization.
- Recyclability: Low non-fissile absorption in 233U facilitates multiple recycling cycles, improving fuel efficiency.
- Improved fuel utilization: Thorium can produce more fissile uranium-233 than is consumed in water-cooled or molten-salt reactors, ensuring efficient fuel utilization.