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India's nuclear power programme

India's nuclear programme has reached the second of its three stages: the Prototype Fast Breeder Reactor at Kalpakkam went critical in April 2026, decades behind schedule, against a fleet of 24 reactors and 8.78 GW. The target is 100 GWe by 2047, which needs small modular reactors and private money, and the law that opened the sector is now before the Supreme Court over its liability caps.

UPSC has asked

Prelims 2023: why India depends on coal despite having uranium deposits
Prelims 2022: monazite as a source of thorium and rare earths
Prelims 2020: why some Indian nuclear reactors are under international safeguards

The three-stage programme

Stage 1: PHWRs
Natural uranium fuel, heavy water as moderator and coolant; plutonium builds up in the spent fuel
Stage 2: fast breeders
Plutonium and depleted uranium fuel; a thorium blanket is converted into uranium-233
Stage 3: thorium reactors
That uranium-233 fuels advanced reactors

From The Indian Express, 4 September 2026

Homi J. Bhabha drew the sequence up for India's modest uranium reserves and its large thorium, much of it in coastal monazite.
Thorium-232 is fertile rather than fissile: it absorbs a neutron and decays through protactinium-233 into fissile uranium-233.
Each stage waits on the one before it, so a delay in Stage 2 postpones thorium by as long again.

The reactor types

A pressurised heavy water reactor (PHWR) is the Stage 1 design, fuelled by natural uranium with heavy water as both moderator and coolant.
A fast breeder runs on mixed oxide (MOX) fuel, cooled by liquid sodium, behind a blanket of uranium-238 that absorbs neutrons and becomes fissile plutonium-239.

Who runs it, and the law that opened it

The Department of Atomic Energy (DAE) runs the programme and the Bhabha Atomic Research Centre (BARC) designs the reactors.
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.

What it is aiming at

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.

Fissile and fertile: Fissile material such as plutonium-239 or uranium-233 can sustain a chain reaction; fertile material such as uranium-238 or thorium-232 must first absorb a neutron and be converted into it.

Breeder reactor: A reactor that produces more fissile material than it consumes.

MOX fuel: Mixed oxide (MOX) fuel: a blend of uranium and plutonium oxides.

First criticality: The moment a reactor first sustains a nuclear chain reaction on its own.

Small modular reactor: A factory built reactor of up to about 300 MWe, made in modules rather than poured in concrete on site.

Pressurised water reactor: A reactor cooled and moderated by ordinary water held at high pressure.

burn-up: The energy drawn from a given mass of nuclear fuel before it is spent and removed from the reactor.

Copper-chlorine cycle: A thermochemical process that uses heat to split water into hydrogen.

Special Drawing Rights: An international reserve asset created by the International Monetary Fund (IMF) and used as a unit of account rather than as a currency.

What has happened

2 Sep 2026
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.
The Indian Express, 4 Sep 2026: Nuclear scientist's energy pitch: Why India needs transition to thorium-based fuel? (opens in a new tab)
18 Aug 2026
The Supreme Court issued notice to the Centre and the Atomic Energy Regulatory Board on a challenge to the liability 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.
The Hindu, 18 Aug 2026: Supreme Court questions nuclear liability caps in the SHANTI Act (opens in a new tab)
15 Aug 2026
The Prime Minister said five indigenous small modular reactors (SMRs) will be running by 2033, and BARC's three designs were set out.
- 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.
PIB, 15 Aug 2026: Small Modular Reactors, the SHANTI Act and the 100 GW goal (opens in a new tab)
13 Aug 2026
A Rajya Sabha reply confirmed that the Prototype Fast Breeder Reactor (PFBR) at Kalpakkam reached first criticality on 6 April 2026, opening Stage 2.
- About 90 per cent Indian built, it was commissioned with a robot and ultrasonic imaging that see through its opaque liquid sodium.
- The fleet stands at 24 reactors and 8.78 GW, with ten 700 MW PHWRs to take it to about 22,480 MW by 2031-32.
- Design changes after Fukushima, late Russian supplies at Kudankulam and difficult soil at Gorakhpur held it up for decades.
PIB, 13 Aug 2026: PFBR criticality and status of India's reactor fleet (opens in a new tab)