Nuclear energy

Also called: Atomic energy · Topic: Energy Resources of India: Conventional and Non-conventional · NCERT: Class 10, Ch 5 "Minerals and Energy Resources"; Class 12, Ch 5 "Mineral and Energy Resources"

Meaning

Nuclear energy (also called atomic energy) is the heat released when the centre (nucleus) of a heavy atom such as uranium-235 or plutonium-239 splits. This splitting is called fission. The heat is then used to make electricity. Thorium does not split directly. A reactor first changes it into fissile U-233 [3].

• It matters because it gives baseload power, the minimum electricity the grid needs all day and all night without a break. It is also low-carbon: its lifecycle emissions are similar to those of hydro and wind power [2].
• India has a lot of thorium but limited uranium [2]. Because of this mismatch, India follows its own three-stage nuclear power programme.

Explanation

How a nuclear power plant works (cause → process → result)

• Fission starts the process:
• A neutron strikes a uranium or plutonium nucleus. The nucleus splits into two smaller atoms.

• The split releases a lot of heat and more neutrons. These neutrons split more atoms. This is a controlled chain reaction [3].

• Heat becomes electricity:

• The heat turns water into high-pressure steam.

• The steam spins a turbine, and the turbine drives a generator that makes electricity [3].

• Criticality is the point where a steady, controlled chain reaction begins. Here, the neutrons made by fission equal the neutrons lost, so the power output stays stable [2].

• Fusion is different. It joins light atoms together, and it is what powers the Sun. It cannot yet make electricity on a commercial scale. All nuclear power plants use fission [3].

Fuels: fissile and fertile

• Fissile fuel can keep a chain reaction going by itself. Examples are U-235, Pu-239 and U-233 [3].
• Fertile material cannot keep a chain reaction going. Inside a reactor it first changes into fissile fuel. Examples are U-238 and Th-232 [3].

• Thorium (Th-232) absorbs a neutron and becomes U-233, which is fissile [3].

• India's uranium is low grade (there is little uranium in each tonne of rock), so imports must add to it [3].

• The 2008 NSG waiver (the Nuclear Suppliers Group is the group of countries that controls nuclear trade) let India import uranium fuel even though India has not signed the NPT.
• India has civil nuclear cooperation agreements with 18 countries (2026) [2].

Reactor types and the three-stage programme

• India's reactor types [3]:
• Mostly PHWRs (pressurised heavy water reactors), which use natural uranium.
• BWRs (boiling water reactors: water boils inside the reactor core, and the steam runs the turbine directly) at Tarapur.

• PWRs (pressurised water reactors) at Kudankulam.

• PHWR: Heavy water is water in which ordinary hydrogen is replaced by deuterium, a heavier form of hydrogen. It does two jobs:

• It is the moderator: it slows neutrons down so they can split natural uranium.
• It is the coolant: it carries heat away from the core.

• Because natural uranium works as fuel, India needs no enrichment plants for this stage [3].

• The three-stage programme: Homi J. Bhabha proposed it in 1954 [3]. It uses a closed fuel cycle (spent fuel is reprocessed and reused, not thrown away). In the end it will run on thorium [2].

Stage	Reactor	Fuel	Output for the next stage
1	PHWR	Natural uranium [3]	Plutonium recovered from spent fuel [2]
2	Fast breeder reactor (FBR), e.g. the PFBR	Uranium-plutonium MOX (mixed oxide) fuel [2]	More plutonium; later U-233 from thorium [2]
3	Thorium-based reactors	U-233 made from thorium	Long-term energy security from thorium [2]

• Prototype Fast Breeder Reactor (PFBR), Kalpakkam:
• It is 500 MWe and sodium-cooled. IGCAR designed it and BHAVINI built it [2].
• "Fast" means it uses fast neutrons and has no moderator. Liquid sodium carries heat well and does not slow neutrons much.
• "Breeder" means it makes more fuel than it burns. A U-238 blanket around the core turns into fissile Pu-239. Later, a Th-232 blanket will turn into U-233 [2].
• Core loading began in March 2024. First criticality came on 6 April 2026. With this, India formally entered Stage 2 [2].

• About 90% of its equipment was made in India [3].

• Waste: India reprocesses its spent fuel. It is one of the few countries with vitrification technology, which locks high-level radioactive waste into stable glass [3].

Capacity, institutions and reforms

• Capacity now: 24 reactors with 8.78 GW (2026) [3]. They generated 56,681 million units in 2024-25. That was 3.1% of India's electricity [2].
• Pipeline: Nine reactors with 7.5 GW are under construction. Ten indigenous PHWRs are approved in fleet mode (many identical reactors ordered together to save cost and time). Pre-project work is approved for two 500 MW fast breeder reactors [3].
• Targets: 22.38 GW by 2031-32 [2] and 100 GW by 2047 under the Nuclear Energy Mission (Union Budget 2025-26) [2][4].
• Institutions:
• AEC (1948): the top policy body.
• BARC, Trombay: began in 1954 as the Atomic Energy Establishment and was renamed in 1967.
• NPCIL runs the power reactors.
• AERB is the safety regulator.

Where it occurs

Uranium (mostly in old Dharwar rocks, which are Precambrian and rich in metallic minerals)

• Jaduguda, Singhbhum copper belt, Jharkhand: India's first uranium mine (1967), on the Chota Nagpur plateau.
• Tummalapalle, YSR Kadapa district, Andhra Pradesh: 60,000 tonnes of uranium. The mine was commissioned on 20 April 2012. It was UCIL's first project outside Jharkhand, and it uses alkali pressure leaching [5].
• Udaipur, Alwar and Jhunjhunu (Rajasthan, Aravalli belt); Durg (Chhattisgarh); Bhandara (Maharashtra); Kullu (Himachal Pradesh).
• AMD has proved about 4,36,700 tonnes of in-situ U₃O₈ in 47 deposits (2025) [6].

Thorium (in monazite, found in placer sands: heavy minerals that waves and rivers sort and pile up along the coast)

• Kerala (Palakkad, and Kollam on the Chavara coast), the Tamil Nadu coast, near Visakhapatnam (Andhra Pradesh) and the Mahanadi delta (Odisha).
• The official list also includes West Bengal and Jharkhand [3]. Monazite resources are 13.15 million tonnes (September 2025) [7].

Power stations (reactors need a lot of cooling water, so stations sit on the coast or near rivers)

Station	State	Water source	Key fact
Tarapur	Maharashtra (Palghar)	Arabian Sea	First station (1969); US-built BWRs
Rawatbhata	Rajasthan (near Kota)	Chambal (Rana Pratap Sagar)	PHWR site
Kalpakkam	Tamil Nadu (Chengalpattu)	Bay of Bengal	PFBR, IGCAR, BHAVINI
Narora	Uttar Pradesh (Bulandshahr)	Ganga	Seismically active Ganga plain
Kaiga	Karnataka (Uttara Kannada)	Kali	Western Ghats
Kakrapar	Gujarat (near Surat)	Tapi	First indigenous 700 MWe PHWRs (2023)
Kudankulam	Tamil Nadu (Tirunelveli)	Gulf of Mannar	Russian VVER-1000; Units 1 and 2 running since 2013 and 2016
Jaitapur	Maharashtra (Ratnagiri)	Konkan coast	Six French EPRs planned; stalled

Don't confuse with

• Fission vs fusion: Fission splits heavy atoms and runs every nuclear power plant. Fusion joins light atoms, powers the Sun, and is not yet used to make electricity commercially [3].
• Fissile vs fertile: Fissile fuel (U-235, Pu-239, U-233) can keep a chain reaction going. Fertile material (U-238, Th-232) must first change into fissile fuel inside a reactor [3].
• PHWR vs BWR: PHWRs use natural uranium with heavy water and are India's main reactor type. Tarapur, the first station, uses US-built BWRs, not PHWRs.
• Breeder reactor vs ordinary reactor: A fast breeder like the PFBR uses fast neutrons with no moderator. It makes more fuel than it burns [2]. A PHWR slows its neutrons with heavy water and does not breed extra fuel.

Prelims Hooks

• First uranium mine: Jaduguda (Singhbhum, Jharkhand), 1967. Large newer deposit: Tummalapalle (YSR Kadapa, Andhra Pradesh), commissioned 2012 [5].
• Thorium mineral: monazite, found in the beach sands of Kerala (Chavara/Kollam), Tamil Nadu, Andhra Pradesh and Odisha.
• Trap: Tarapur (Maharashtra, 1969) is India's first station, and it uses boiling water reactors, not PHWRs. Foreign partners: Kudankulam–Russia (VVER-1000), Jaitapur–France (EPR), Tarapur 1 and 2–USA (BWR).
• Station–river pairs: Rawatbhata–Chambal (Rajasthan); Narora–Ganga (Uttar Pradesh); Kaiga–Kali (Karnataka); Kakrapar–Tapi (Gujarat).
• Three-stage fuels in order: natural uranium (PHWR) → plutonium/MOX (FBR) → U-233 from thorium. The PFBR (500 MWe, sodium-cooled, Kalpakkam) reached first criticality on 6 April 2026. India will be the second country after Russia to run a commercial FBR [2].
• SHANTI Act, 2025: replaces the Atomic Energy Act, 1962 and the CLND Act, 2010. It lets private firms in, but reprocessing and heavy water production stay with the Central Government. It makes the AERB a statutory body (one set up under a law) [4].

Mains Points

• Resource mismatch shapes strategy (GS-III):
• India's uranium is limited and low grade, but its thorium reserves are among the world's largest [2].
• So India chose a closed-fuel-cycle, three-stage path. The PFBR's criticality in 2026 opens Stage 2 [2].

• Stage 3 needs enough plutonium and U-233 to be bred first. Until then, fuel imports (allowed by the 2008 NSG waiver) and fleet-mode PHWRs remain vital.

• Distribution pattern (GS-I):

• Stations sit on the coast (Tarapur, Kalpakkam, Kudankulam, Jaitapur) or near big rivers (Rawatbhata, Narora, Kaiga, Kakrapar), because reactors need cooling water.

• Uranium comes from Peninsular shield rocks (Singhbhum, Kadapa basin), and thorium comes from coastal placer sands. So mineral areas and power stations are often far apart.

• Slow growth and policy response (GS-III):

• Nuclear power gives only about 3% of India's electricity [2]. Land disputes and protests (Kudankulam, Jaitapur), seismic risk (Narora) and nuclear liability have delayed projects.
• The response:
  • The Nuclear Energy Mission: ₹20,000 crore for SMRs (small modular reactors of up to about 300 MWe, built from factory-made modules), with at least five indigenous SMRs by 2033 [2][4].
  • The SHANTI Act: private investment, graded liability (the limit depends on the type of installation) and a statutory AERB [4].
• Clean baseload power also helps the grid take in more renewables on the path to net zero by 2070.

Related concepts

• Uranium
• Thorium
• Bhabha Atomic Research Centre
• Tarapur Atomic Power Station
• Kudankulam Nuclear Power Plant
• Jaitapur nuclear project
• Three-stage nuclear power programme
• Pressurised heavy water reactor
• Prototype Fast Breeder Reactor
• Small modular reactor

Read more

• Nuclear energy: minerals, power stations and the three-stage programme