On 6 April 2026, a reactor at Kalpakkam went critical for the first time. It wasn’t just another power plant. It was India’s first fast breeder reactor, a technology only a handful of countries have mastered. This article covers India’s nuclear reactor fleet — the types in service, and the new designs entering it.
Must Know
India’s reactor fleet
- CountIndia operates 24 nuclear reactors (8.78 GW) across 7 sites in 6 states.
- TypesThe fleet has 20 PHWRs, 2 BWRs and 2 PWRs (VVER type).
- NewcomerThe PFBR at Kalpakkam is India’s first fast breeder reactor.
- Why it mattersBecause a mix of reactor types gives India options and resilience.
The three reactor lineages
- PHWRIndigenous Pressurised Heavy Water Reactors form the bulk of the fleet.
- VVERRussian-design VVER-1000s run at Kudankulam.
- BreederA homegrown fast breeder reactor is now coming online.
- Why it mattersBecause each lineage marks a different stage of technological self-reliance.
Good to Know
The PFBR breakthrough
- CriticalityThe PFBR at Kalpakkam attained first criticality on 6 April 2026.
- OperatorIt is run by BHAVINI, developed by IGCAR, not by NPCIL.
- FuelIt runs on Uranium-Plutonium Mixed Oxide (MOX) fuel.
- HowFast neutrons turn non-fissile Uranium-238 into fissile Plutonium-239.
- Why it mattersBecause it produces more fuel than it consumes, a key to the thorium plan.
Why fast breeders matter for thorium
- Bhabha PlanIndia’s three-stage plan moves from uranium to thorium.
- Stage 3Thorium reactors cannot begin at scale until fast breeders prove they work.
- ThoriumIndia holds vast thorium reserves it wants to turn into usable fuel.
- Why it mattersBecause fast breeders are the bridge to using India’s abundant thorium.
Kudankulam and Kakrapar
- KudankulamKudankulam runs Russian VVER-1000 reactors; units 1-2 operate, 3-6 are being built.
- KAPPKAPP-3 and KAPP-4 at Kakrapar are the largest indigenous 700 MWe PHWRs.
- Self-relianceIndia is building a fleet of 10 indigenous 700 MW PHWRs.
- Why it mattersBecause these projects expand both Russian-built and home-built capacity.
All 7 nuclear reactor sites in India
- TarapurTarapur (TAPS) in Maharashtra, the oldest site, runs 4 units since 1969.
- RawatbhataRawatbhata (RAPS) in Rajasthan, the largest site by units, runs 6 reactors.
- KakraparKakrapar (KAPS) in Gujarat runs 4 units, including the 700 MWe PHWRs.
- KalpakkamKalpakkam (MAPS) in Tamil Nadu runs 2 units and hosts the PFBR breeder.
- KudankulamKudankulam (KKNPP) in Tamil Nadu runs 2 Russian VVER-1000 units.
- NaroraNarora (NAPS) in Uttar Pradesh runs 2 units.
- KaigaKaiga (KGS) in Karnataka runs 4 units.
- BuildingNew sites under construction include Gorakhpur (Haryana), Chutka (MP) and Mahi Banswara (Rajasthan).
- Why it mattersBecause knowing where each reactor type sits is a common exam question.
✅ Test Yourself
Work through a 5-question chain on Nuclear Reactors of India, then keep practising with a random Science & Technology question.
Great to Know
Why PFBR was hard to build
- DelayPFBR’s criticality came more than 15 years behind schedule.
- HardFast-breeder technology is mastered by only a handful of countries.
- EngineeringIGCAR handled sodium systems, materials and safe sodium handling.
- LocalNearly 90% of PFBR’s equipment and systems were made in India.
- ToolsIGCAR built remote tools like DISHA to inspect hot reactor welds.
- Why it mattersBecause building PFBR pushed India’s nuclear engineering far forward.
PYQ / Exam Angle
UPSC 2020: IAEA safeguards
- UPSC 2020UPSC and other competitive exams ask why some Indian reactors are under IAEA safeguards. View this question
- Point testedThe exam checks the difference between safeguarded and unsafeguarded reactors.
- TrapA common wrong answer confuses India’s civil and strategic nuclear facilities.
- RecallReactors under IAEA safeguards are part of India’s civil nuclear cooperation.
Current Affairs / So What
Nuclear energy technology in India (Aug 2026)
- WhatIndia’s nuclear programme runs on the indigenous three-stage plan, moving from uranium to thorium. (Source: PIB)
- GoalIndia aims for 100 GW of nuclear power by 2047, supporting Viksit Bharat. (Source: PIB)
- Why it mattersBecause a self-reliant nuclear sector gives India clean, reliable baseload power. (Source: PIB)
SHANTI Act and nuclear mission (Aug 2026)
- SHANTIThe SHANTI Act, 2025 and the Nuclear Energy Mission for Viksit Bharat drive expansion. (Source: PIB)
- UsesAtomic energy supports healthcare, agriculture, food preservation and clean hydrogen. (Source: PIB)
- SafetyIndia’s programme puts safety first, with layers of protection and emergency preparedness. (Source: PIB)
- Why it mattersBecause nuclear is now a pillar of India’s sustainable energy future. (Source: PIB)
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