The three stage nuclear programme

Prelims and MainsCurrent affairs on this: Nuclear power programme

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.

• 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-232 absorbs a neutron and decays through protactinium-233 into fissile uranium-233; thorium absorbs neutrons more strongly than uranium, so thorium bearing fuel needs high burn up if it is not to raise uranium use and cost.

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.

See also: Pressurised heavy water reactors · The Prototype Fast Breeder Reactor · Small modular reactors · The SHANTI Act · The Nuclear Energy Mission