Science and Technology › Nuclear technology
Nuclear power programme
India's nuclear power programme: its three stages and their reactors, thorium, small modular reactors, uranium and the fuel cycle, nuclear waste, and the law on liability and private participation. Prelims has asked why India depends on coal despite having uranium deposits.
UPSC has asked
- Prelims 2023: why India depends on coal despite having uranium deposits
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The three stage nuclear programme
Copy link to The three stage nuclear programmePrelims and MainsAdded 20 September
Homi Bhabha designed India's nuclear programme in the 1950s around one fact of geology: little uranium and a great deal of thorium, held in coastal monazite sands. Thorium is fertile, not fissile: it cannot sustain a chain reaction on its own and must first be turned into uranium 233 inside a reactor. So the programme runs in three stages, each handing fuel to the next: heavy water reactors on natural uranium, which make plutonium; fast breeders on that plutonium, which make uranium 233 from thorium; and thorium reactors on uranium 233. That is why India kept reprocessing spent fuel, and why the 2008 Nuclear Suppliers Group (NSG) waiver mattered.
Three stages, three fuels
Stage 1, PHWR
Fuel natural uranium; moderator and coolant heavy water; product plutonium 239 in spent fuel.
Imported uranium after the 2008 NSG waiver relieves this stage.
Stage 2, fast breeder
Fuel plutonium 239; blanket uranium 238 and thorium; product more plutonium and uranium 233; PFBR critical since 6 April 2026.
Stage 3, thorium reactor
Fuel uranium 233 with thorium; product uranium 233 again, a closed cycle; AHWR at design stage.
- Stage 1: pressurised heavy water reactors, natural uranium fuel, heavy water as moderator and coolant, run by the Nuclear Power Corporation of India Limited (NPCIL); the 700 MWe design is the standard for new indigenous units, sanctioned in fleet mode for ten reactors in 2017, of which Kakrapar 3 and 4 and Rawatbhata 7 are operating. India has 24 operating reactors and 8,780 MW of installed nuclear capacity. Output: plutonium 239.
- Stage 2: fast breeders, plutonium fuel, no moderator, liquid sodium coolant, with a blanket of uranium 238 and thorium around the core. The 500 MWe Prototype Fast Breeder Reactor at Kalpakkam, run by Bharatiya Nabhikiya Vidyut Nigam Limited (BHAVINI), began core loading on 4 March 2024 and attained first criticality on 6 April 2026; it is not yet in commercial operation, so its 500 MWe is not in the installed figure. India becomes the second country after Russia to run a commercial scale fast breeder.
- Stage 3: uranium 233 with thorium; the 300 MWe Advanced Heavy Water Reactor design at the Bhabha Atomic Research Centre (BARC), light water cooled and heavy water moderated, fuelled with thorium based mixed oxide, is still at the design stage. The one working example of the fuel is KAMINI at Kalpakkam, a small IGCAR research reactor and the only reactor in the world fuelled by uranium 233.
- The bodies: the Department of Atomic Energy at the top; BARC for research and the fuel cycle; NPCIL and BHAVINI as operators; the Indira Gandhi Centre for Atomic Research (IGCAR) at Kalpakkam for fast reactors, where the Fast Breeder Test Reactor (FBTR) has run since 1985; the Atomic Energy Regulatory Board as regulator, set up by administrative order in 1983 and made statutory by the SHANTI Act, 2025.
- The NSG waiver of 6 September 2008 and the India specific safeguards agreement INFCIRC/754, in force from 11 May 2009, let India import uranium and reactors for the civilian side; 16 reactors totalling 6,380 MW are under IAEA safeguards.
Thorium geography
Monazite occurs in coastal beach and teri sands and inland alluvium across about nine States. The official resource is about 13.15 million tonnes of monazite; the older and widely quoted figure is 11.93 million tonnes, containing roughly 1.07 million tonnes of thorium. Andhra Pradesh holds the largest share, ahead of Tamil Nadu, Odisha and Kerala.
Mains: The three stage plan trades time for fuel security: it will take longer than a uranium fleet, but it is the only route by which India's own thorium becomes electricity, which is why India kept the breeder programme while others abandoned theirs.
UPSC has asked
- Mains 2026: fast breeder and thermal reactors, and what criticality at Kalpakkam means
- Mains 2017: the growth of nuclear science in India and the advantage of the fast breeder programme
What changed
2 Sep 2026
13 Aug 2026
PIB, 13 Aug 2026: PFBR criticality and status of India's reactor fleet (opens in a new tab)
29 Jul 2026Update
- With the fast breeder critical, India has entered the second stage. Thorium will be used at scale only after enough breeder capacity exists.
- Uranium-233 bred from thorium already fuels KAMINI at Kalpakkam, the only reactor in the world to run on it, and a molten salt reactor is being developed for thorium.
- High level liquid waste is fused into glass, and separating caesium-137, ruthenium-106 and strontium-90 for medical use shrinks what remains.
PIB, 29 Jul 2026: PARLIAMENT QUESTION: RADIOACTIVE WASTES (opens in a new tab) · PIB, 23 Jul 2026: PARLIAMENT QUESTION: NUCLEAR FUEL PROGRAMME (opens in a new tab)
Background reading: The Indian Express, 4 Sep 2026: Nuclear scientist's energy pitch: Why India needs transition to thorium-based fuel? (opens in a new tab)
See also: Pressurised heavy water reactors · The Prototype Fast Breeder Reactor · Thorium · Small modular reactors · The SHANTI Act · The Nuclear Energy Mission
Pressurised heavy water reactors
Copy link to Pressurised heavy water reactorsPrelims and Mains
Stage 1 is the fleet India actually operates, and it runs on uranium as it comes out of the ground. Almost everything now under construction is the same design in a larger version.
- A pressurised heavy water reactor (PHWR) is the Stage 1 design, fuelled by natural uranium with heavy water as both moderator and coolant.
- Ten 700 MW PHWRs are to take installed nuclear capacity to about 22,480 MW by 2031-32.
- Design changes after Fukushima, late Russian supplies at Kudankulam and difficult soil at Gorakhpur held the expansion up for decades.
What changed
The Prototype Fast Breeder Reactor
Copy link to The Prototype Fast Breeder ReactorPrelims and Mains
Stage 2 opened at Kalpakkam in April 2026, about two decades after it was meant to, with a reactor India built almost entirely itself. Its engineering difficulty is its coolant: liquid sodium carries heat superbly and is completely opaque, so the machine cannot be inspected by eye.
- The Prototype Fast Breeder Reactor (PFBR) reached first criticality on 6 April 2026, confirmed in a Rajya Sabha reply in August.
- It runs on MOX fuel and is cooled by liquid sodium.
- Its blanket of uranium-238 absorbs neutrons and becomes fissile plutonium-239.
- About 90 per cent Indian built, it was commissioned with a robot and ultrasonic imaging that see through the sodium.
What changed
Thorium
Copy link to ThoriumPrelims and Mains
India's uranium reserves are modest and its thorium is large, much of it in the monazite of the coastal sands, which is why the programme ends where it does. The obstacle is the difference between fissile and fertile material: thorium is the second kind, and a reactor has to make a fuel of it first.
- Thorium-232 absorbs a neutron and decays through protactinium-233 into fissile uranium-233.
- Anil Kakodkar, a former chairman of the Atomic Energy Commission, urged thorium bearing fuel in the existing PHWRs now, rather than waiting on the breeders for uranium-233.
- Thorium absorbs neutrons more strongly than uranium, so the fuel needs high burn-up if it is not to raise uranium use and cost.
What changed
Background reading: The Indian Express, 4 Sep 2026: Nuclear scientist's energy pitch: Why India needs transition to thorium-based fuel? (opens in a new tab)
See also: Monazite and the beach sands
Small modular reactors
Copy link to Small modular reactorsPrelims and Mains
A small modular reactor is built in a factory and assembled on site, which is meant to take years and capital out of a technology that has been short of neither. India is designing three at once, and they are not variations on one another.
- The Prime Minister said five indigenous SMRs will be running by 2033.
- BSMR-200 of 220 MWe and SMR-55 of 55 MWe are pressurised water reactors for Tarapur.
- A high temperature gas cooled reactor of up to 5 MWth at BARC Visakhapatnam is to make hydrogen by the copper-chlorine cycle.
What changed
The SHANTI Act
Copy link to The SHANTI ActPrelims and Mains
The law that let private companies into nuclear power also settled who pays if a plant fails, and that second half of it is now before the Supreme Court. A cap on liability is what makes the risk insurable, which is the argument for it and, to the petitioners, the argument against.
- The Sustainable Harnessing and Advancement of Nuclear Energy for Transforming India (SHANTI) Act, 2025, notified on 21 December 2025, lets private companies into nuclear power under licence.
- The same Act gave the Atomic Energy Regulatory Board (AERB) statutory status and set graded liability in line with international conventions.
- It caps the government's residual liability at 300 million Special Drawing Rights and an operator's at ₹3,000 crore, and exempts equipment suppliers altogether.
- The Supreme Court issued notice to the Centre and the AERB on a challenge to the caps.
- It asked whether a statutory cap can stop a constitutional court awarding victims fair compensation.
- Petitioners set the caps against the estimated costs of Chernobyl and Fukushima.
What changed
18 Aug 2026
15 Aug 2026
PIB, 15 Aug 2026: Small Modular Reactors, the SHANTI Act and the 100 GW goal (opens in a new tab)
23 Jul 2026Update
- The SHANTI Act caps liability for a nuclear incident at the rupee equivalent of 300 million Special Drawing Rights, grades the operator's share by reactor size, and makes the Centre liable beyond the cap. Its rules are still being drafted.
The Nuclear Energy Mission
Copy link to The Nuclear Energy MissionPrelims and Mains
Everything above is aimed at a single number, and it is more than ten times the capacity running today. Two decades is not long for a technology whose last expansion slipped by that much.
- The Nuclear Energy Mission sets a target of 100 GWe by 2047.
- About half of that is expected from indigenous PHWRs, a fleet heading towards 50 to 60 GW.
- Reaching it needs private and foreign capital, which is why the liability terms decide the pace.
What changed
15 Aug 2026
PIB, 15 Aug 2026: Small Modular Reactors, the SHANTI Act and the 100 GW goal (opens in a new tab)
30 Jul 2026Update
- Installed capacity is 8.78 GW against a target of 100 GW by 2047. Twenty reactors are under implementation, ten under construction and ten in pre project work, including two 500 MW fast breeder reactors at Kalpakkam.
PIB, 30 Jul 2026: PARLIAMENT QUESTION: EXPANSION OF NUCLEAR POWER CAPACITY (opens in a new tab) · PIB, 29 Jul 2026: PARLIAMENT QUESTION: NUCLEAR ENERGY MISSION (opens in a new tab)
Uranium from Australia
Copy link to Uranium from AustraliaPrelims and Mains
Australia holds more than a quarter of the world's uranium reserves and long refused to sell to countries outside the Nuclear Non-Proliferation Treaty; India, outside the treaty but exempted by the Nuclear Suppliers Group in 2008, signed a civil nuclear cooperation agreement with it in 2015.
What changed
14 Jul 2026New subject
- After the third annual summit on 9 July, India and Australia finalised the arrangements for uranium exports under their 2015 nuclear cooperation agreement, for peaceful use under International Atomic Energy Agency safeguards.
- Australia holds more than a quarter of the world's uranium reserves and long refused uranium to countries outside the Nuclear Non-Proliferation Treaty. India is outside it but received an exemption from the Nuclear Suppliers Group in 2008.
- Private Australian miners can now contract with Indian private firms, which the SHANTI Act of 2025 allows into the sector.
The Hindu, 14 Jul 2026: What is the India-Australia uranium supplies agreement? (opens in a new tab) · The Indian Express, 15 Jul 2026: Australia agrees to supply uranium to India, reversing its long-standing non-proliferation objection (opens in a new tab)
Also filed elsewhere
- Green status for nuclear power · on Climate finance, carbon markets and carbon pricing
A green label is worth asking for because it lowers the cost of capital, and nothing needs that more than a plant that takes a decade to build and longer to pay back.
- Monazite and the beach sands · on Critical minerals and rare earths
The sands of India's southern coast carry monazite, the mineral that holds both thorium and rare earths.