Nuclear Reactors of India

India runs 24 power reactors with a combined capacity of 8,780 MW, or 8.78 GW. This is the list of the Nuclear Power Corporation of India Limited (NPCIL), as seen in October 2026. Three types make up the fleet: 20 PHWRs, 2 BWRs and 2 PWRs.

What do the letters mean?

PHWR stands for pressurised heavy water reactor. BWR stands for boiling water reactor. PWR stands for pressurised water reactor. NPCIL uses these same three names in its table.

In a PHWR, heavy water slows the neutrons. Natural uranium is the fuel.

Where are the reactors?

The 24 reactors stand at seven sites in six states. Tamil Nadu has two sites.

Why is one Rajasthan unit missing?

Unit 1 at Rawatbhata (RAPS-1) has 100 MW. It is under extended shutdown. The Government leaves it out of the count of 24.

Twenty of the 24 reactors are PHWRs, so this is the family that carries most of India’s nuclear power. The design started with a Canadian model and then became Indian.

Where did the design come from?

The first PHWR was Rajasthan 1. Atomic Energy of Canada Ltd and NPCIL built it together. Canada’s Douglas Point reactor was its model. It started up in 1972. The World Nuclear Association (WNA) says later Indian PHWRs grew from these units.

How did the units grow in size?

Each new design was larger than the last.

• 220 MW: the standard unit at Madras, Narora, Kaiga, Kakrapar 1 and 2, and most of Rawatbhata.
• 540 MW: Tarapur 3 and 4. The WNA says they grew from the 220 MW model and were built by NPCIL.
• 700 MW: Kakrapar 3 and 4, and Rawatbhata 7.

When did the 700 MW units start?

NPCIL lists three dates for commercial operation:

1. Kakrapar 3: 30 June 2023.
2. Kakrapar 4: 31 March 2024.
3. Rawatbhata 7: 15 April 2025.

The two Kakrapar units cost over Rs 22,500 crore, said NPCIL officials to IANS. The report is dated 21 February 2024. It said the Prime Minister would dedicate them to the nation the next day, 22 February 2024.

What does the Tarapur site look like?

Tarapur holds the oldest reactors in India. It also holds the two 540 MW PHWRs of 2005 and 2006.

Four reactors are not PHWRs: the two BWRs at Tarapur and the two VVER reactors at Kudankulam. Both pairs came from abroad.

What are the Tarapur BWRs?

General Electric built them on a turnkey contract. They were built before the Nuclear Non-Proliferation Treaty, says the WNA. NPCIL lists commercial operation for both on 28 October 1969.

They use imported enriched uranium and sit under IAEA safeguards. The WNA says Russia has supplied the fuel since 2001.

What are the Kudankulam VVERs?

VVER is the Russian name for a pressurised water reactor. Kudankulam has two VVER-1000 units. Atomstroyexport of Russia supplied them. The deal rests on a 1988 agreement and a 1998 supplement, says the WNA.

• Unit 1: commercial operation on 31 December 2014.
• Unit 2: commercial operation on 31 March 2017.

The WNA says these two units stood apart from India’s three-stage plan. They were meant to add power quickly. Units 1 and 2 had made over 121 billion units by April 2026, says Power Peak Digest.

What is next at Kudankulam?

Units 3 to 6 are under construction. On 25 April 2026, NPCIL began the “spillage to open reactor” step for Unit 3. This step flushes the safety systems and main coolant pipes with light water. When all six units run, the site will have 6,000 MW.

Nuclear plants made 56,681 million units (MU) of electricity in 2024-25. The IANS report of 23 July 2025 says this was about 3 per cent of India’s total. Minister Jitendra Singh gave the figures to Parliament.

How has output changed?

The Pioneer report of 20 March 2026 gives three years of output.

How well do the plants run?

NPCIL gives a capacity factor of 89 per cent for April to August 2026. Its availability factor is 94 per cent. A capacity factor shows how much of the possible output a plant really produced.

NPCIL also says its plants had made over 1.0 million MU since October 1969, up to August 2026.

Why do two capacity numbers appear?

NPCIL’s total is 8,780 MW. The WNA counts 7,935 MWe for the same 24 reactors. World Nuclear News says about 7,900 MW.

The WNA table shows net capacity. It gives Tarapur 3 and 4 as 540 MWe gross and 490 MWe net. NPCIL lists 540 MW for each. So the two totals count in different ways.

What is the target for 2031-32?

India plans to reach 22,380 MW by 2031-32. The sum is 8,780 MW now plus 13,600 MW now being built or prepared. That 13,600 MW includes the 500 MW PFBR.

India’s plan moves from natural uranium to plutonium and then to thorium. The WNA calls the long-term goal an advanced heavy water thorium cycle.

What happens in each stage?

• Stage 1: PHWRs on natural uranium, and light water reactors, make power. Plutonium appears as a by-product.
• Stage 2: Fast reactors burn that plutonium. A blanket of uranium and thorium around the core makes more plutonium and uranium-233.
• Stage 3: Advanced heavy water reactors (AHWRs) burn thorium-plutonium fuels. They breed uranium-233.

Why did India choose this path?

The WNA says India’s uranium resources are modest. Its thorium is abundant. The Atomic Minerals Directorate (AMD) reports almost 12 million tonnes of monazite. Monazite is a sand that carries thorium, usually 6 to 7 per cent. The WNA says it might hold 700,000 tonnes of thorium.

Where does recycling fit in?

Stage 2 needs plutonium from used fuel. World Nuclear News says the plutonium comes from reprocessing used fuel of the PHWRs and light water reactors. The WNA says India will reprocess the used Kudankulam fuel too.

The PFBR is a 500 MWe reactor at Kalpakkam in Tamil Nadu. It reached first criticality on 6 April 2026 at 8:25 pm. The Department of Atomic Energy (DAE) announced this. India thus moved into the second stage of its plan.

What does first criticality mean?

It is the start of a controlled fission chain reaction. World Nuclear News used those words. The Atomic Energy Regulatory Board (AERB) gave its clearance after a review.

Who designed it and who built it?

The Indira Gandhi Centre for Atomic Research (IGCAR) designed and developed the technology. Bharatiya Nabhikiya Vidyut Nigam Ltd (BHAVINI) built and commissioned the reactor. BHAVINI is a government enterprise under the DAE.

So NPCIL does not run this one. The old fleet belongs to NPCIL. The breeder belongs to BHAVINI.

How late was it?

Construction began in 2004. The first target date was 2010. First criticality came in 2026, about 16 years after that date. The AERB allowed fuel loading and low-power experiments in mid-2024. Minister Jitendra Singh told Parliament that “first-of-a-kind technological issues” caused the delay.

How does a breeder breed fuel?

The core uses uranium-plutonium mixed oxide fuel, called MOX. A blanket of uranium-238 surrounds the core. The blanket absorbs neutrons and becomes plutonium-239. Plutonium-239 is fissile. So the reactor makes more fuel than it burns.

The design can also place thorium-232 in the blanket. That changes it into uranium-233.

How common are fast reactors?

World Nuclear News, citing the WNA, says some 20 fast neutron reactors have run worldwide since the 1950s. Not all of them were breeders.

What comes after the PFBR?

The Government has approved early work for two more 500 MW fast breeder units at Kalpakkam. It will seek money for them after the PFBR reaches first criticality. The Pioneer report of 20 March 2026 says this.

The WNA says a fuel plant for fast reactors, the FRFCF, was commissioned in 2024. It will serve the PFBR.

Thorium cannot run India’s reactors at scale until fast reactors make enough plutonium. The WNA says that build-up will take another 15 to 20 years.

Why can’t thorium go straight into a reactor?

Thorium-232 is not itself fissile. It must first change into uranium-233. The PFBR blanket can do that job, says World Nuclear News.

How much thorium has India tried?

The WNA says about one tonne of thorium oxide fuel has been irradiated in PHWRs, as an experiment. In 2013, the Bhabha Atomic Research Centre (BARC) warned that an early push for thorium would waste resources. It said India must first build up fissile material.

What did the Prime Minister say?

He called the PFBR “a decisive step towards harnessing our vast thorium reserves” in stage three. World Nuclear News carried the quote.

What is the AHWR?

The AHWR is the reactor for stage three. It burns thorium-plutonium fuel and breeds uranium-233. An AHWR test facility opened at BARC in 2008. The WNA says it can use several fuel mixes.

India is building ten 700 MW PHWRs in “fleet mode”, which means the same design in bulk. The Government approved this fleet of 10 units, or 7,000 MW. NPCIL buys the parts in bulk.

Which projects are in the fleet?

Who builds Mahi Banswara?

Anushakti Vidhyut Nigam Ltd (ASHVINI) builds it. ASHVINI is a joint venture of NPCIL and NTPC.

What else is coming?

• Rawatbhata 7 and 8: Unit 7 is in commercial operation. Unit 8 was in advanced commissioning, says NPCIL.
• Kudankulam 3 to 6: four 1,000 MW units with Russia.
• Gorakhpur 1 and 2: two 700 MW units under construction.

What does the Government plan for 2047?

The Finance Minister said in February 2025 that India needs at least 100 GW of nuclear energy by 2047.

The Nuclear Energy Mission for Viksit Bharat promised Rs 20,000 crore for at least five Indian-designed small modular reactors by 2033. The WNA also says the SHANTI Act 2025 replaced the Civil Liability for Nuclear Damage Act 2010.

India uses both imported and home-mined uranium, and that split explains which reactors sit under IAEA safeguards. The WNA calls India’s uranium resources modest and in a high-cost category.

How much uranium does India hold?

The WNA gives 292,867 tonnes of uranium as identified resources in situ. This is the OECD Red Book figure as at January 2021. In situ means still in the ground.

What has the AMD found lately?

Minister Jitendra Singh told the Rajya Sabha that the AMD added 93,700 tonnes of in-situ uranium oxide resources from 2020 to December 2024. It lies in four states.

Andhra Pradesh has 60,659 tonnes and Jharkhand has 27,156 tonnes. Rajasthan and Karnataka hold smaller finds. Swarajya reported this on 4 April 2025.

What are IAEA safeguards?

India signed a safeguards agreement with the International Atomic Energy Agency (IAEA) in 2009. The WNA says 14 reactors were to go under it by the end of 2014. The first Tarapur pair and Kudankulam 1 and 2 are among them.

The rule is simple. Reactors that use imported uranium are placed under IAEA safeguards. Reactors that run on domestic uranium stay outside. The WNA counted 14 safeguarded units and eight indigenous-fuel units in July 2017.

Why did imports begin?

In September 2008, the Nuclear Suppliers Group agreed to let its members trade with India. That ended 34 years of trade isolation, says the WNA. In 2013, India imported about 40 per cent of its uranium needs.

UPSC asked about IAEA safeguards in the 2020 Prelims. This card gives the wording, the answer and the traps.

What did the past paper ask?

How could you answer it?

The answer is (b). Imported uranium brings safeguards. Domestic uranium does not. This follows India’s separation of civil and military facilities.

• Why not (a): thorium is not yet a main fuel.
• Why not (c): foreign firms do not run India’s reactors.
• Why not (d): NPCIL and BHAVINI, both public bodies, run the plants.

What are the traps?

1. Fleet count. 24 reactors: 20 PHWR, 2 BWR, 2 PWR. NPCIL lists 8,780 MW.
2. Operator. NPCIL runs the old fleet. BHAVINI runs the PFBR.
3. Date. PFBR first criticality was on 6 April 2026.
4. Kudankulam. Russian VVER-1000, not a PHWR.
5. Target. 22,380 MW by 2031-32.
6. Thorium. It is stage three, not stage one.