Knowledge Nugget: India–US Thorium Fuel partnership and its significance for UPSC exam

Take a look at the essential concepts, terms, quotes, or phenomena every day and brush up your knowledge. Here’s your UPSC current affairs knowledge nugget on thorium as fuel for nuclear reactors.

(Relevance: Are you aware of the fuels used in nuclear energy plants and the vast thorium reserves in India? Questions have been asked directly on thorium as well as on India’s three-stage Nuclear Programme. In this context, the topic becomes highly important from both Prelims and Mains perspectives.)

Chicago-based Clean Core Thorium Energy (CCTE), only the second American company to have bagged an export licence from the US Department of Energy to sell nuclear technology to India in nearly two decades, will partner NPTC Ltd, the country’s largest power utility, in the development of thorium as an alternative to uranium for fuelling nuclear reactors.

For India, which has little uranium reserves but has abundant deposits of thorium, the latter has been part of a long-term strategy for reducing dependence on imported nuclear fuels.

1. The move signifies the government’s plan to explore the deployment of a thorium-based fuel for India’s existing fleet of Pressurised Heavy Water Reactors (PHWRs), which could, in turn, help buttress the country’s energy and fuel security. The advantage with the thorium fuel produced by the Chicago-based company is that it can be shipped to India and directly loaded on to PHWRs.

2. About Thorium: Thorium, the radioactive metallic element named after the Norse god, has been a long standing hope for India’s true energy security. It has been touted as an alternative to uranium since 1954 by India’s policymakers because it’s more abundant, produces lesser amounts of long-lived radioactive waste (that have a long half life) and potentially lowers the proliferation risk.

3. Thorium itself is not a ‘fissile’ material like uranium, which means that its atoms are not inherently unstable enough for an extra neutron to easily split the nuclei and release energy. But it is classified as ‘fertile’, and can soak in neutrons and transform into the fissile material uranium-233, which can then be split to release energy.

4. In India, thorium deployment has been predicated as the last leg of India’s 3-stage nuclear programme, which could entail reconstructing the country’s nuclear power fleet from the ground up. CCTE has created a new type of fuel that blends thorium with a more concentrated type of uranium named HALEU (high-assay low-enriched uranium). This can then be used in India’s pressurised heavy-water reactors that make up the bulk of the country’s existing fleet.

5. Clean Core’s new fuel, called ANEEL or Advanced Nuclear Energy for Enriched Life, can be potentially deployed in the country’s PHWRs at scale. The combination of thorium with small amounts of enriched uranium and the promise of its use in existing or new PHWR reactors promises to enhance India’s energy security by using domestically available thorium, and improving safety and proliferation resistance.

6. This enables the launch of the thor­ium phase (the third phase of India’s three-stage nuclear programme) earlier, without having to wait for build-up of required fast breeder reactor capacity in the second phase. PHWRs comprise the first phase of the 3-stage programme.

7. Pressurised heavy-water reactors are said to be more suited to handling thorium because heavy water – an isotope of water that has an extra neutron on the hydrogen atom – absorbs fewer neutrons during the fission process, increasing the efficiency of the fission reaction by allowing more neutrons to be absorbed by the thorium.

8. Currently, there are over 45 PHWRs operating worldwide: 19 in India, 17 in Canada, three each in Argentina and South Korea, and two each in China and Romania, according to International Atomic Energy Agency data.

→ STAGE 1: Pressurised Heavy Water Reactors (PHWRs) use natural uranium-based fuels to generate electricity, while producing fissile plutonium (Pu239), which can be extracted by reprocessing the spent fuel. It uses heavy water (deuterium oxide) both as a coolant and moderator. The programme has been supplemented by the construction of imported Light Water Reactors (LWRs).

→ STAGE 2: It involves setting up Fast Breeder Reactors (FBRs) of the kind at Kalpakkam, using plutonium-based fuels, which can enhance nuclear power capacity, and convert fertile thorium into fissile uranium (U233). Reprocessing of the spent fuel is vital for efficient utilisation of the plutonium inventory.

→ STAGE 3: The third stage will be based on the ThU233 cycle. U233 produced in the second stage can be used for the third stage of the power programme, which consists of advanced thermal and fast breeder reactors, for long-term energy security. The Advanced Heavy Water Reactor (AHWR) is proposed for this. Now, the use of molten salt reactors is also seen as an option.

1. Earlier in December, Parliament had passed the Sustainable Harnessing and Advancement of Nuclear Energy for Transforming India (SHANTI) Act, 2025, which marked a major shift in how India’s tightly-controlled nuclear power sector will be governed in the coming years.

2. This Act is an effort to align with norms of global nuclear commerce. It replaces the Atomic Energy Act of 1962 and the Civil Liability for Nuclear Damage Act of 2010 with a single umbrella law.

3. The new law allows public and private companies to set up nuclear power plants and undertake activities related to the transport, storage, import and export of nuclear fuel, technology, equipment and minerals. Until now, these activities were restricted to public sector entities only.

To meet its rapidly growing energy demand, some opine that India should pursue research and development on thorium as the future fuel of nuclear energy. In this context, what advantage does thorium hold over uranium? (UPSC CSE 2012)

1. Thorium is far more abundant in nature than uranium.

2. On the basis of per unit mass of mined mineral, thorium can generate more energy compared to natural uranium.

3. Thorium produces less harmful waste compared to uranium. Which of the statements given above is/are correct?

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