Why does India want fast breeder nuclear reactors? | Explained
Most of India’s current reactors are pressurised heavy water reactors, which are inefficient because only a small fraction of the fuel, around 1%, undergoes fission before it becomes unusable
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Context
The at Kalpakkam has successfully achieved 'criticality', marking a foundational milestone in operationalizing the second stage of India's indigenous nuclear power programme. This development brings India a step closer to utilizing its vast thorium reserves for long-term energy security, despite ongoing challenges related to cost overruns and technical complexities.
UPSC Perspectives
Science & Technology
A nuclear reactor reaches criticality (a state where a nuclear chain reaction becomes self-sustaining) when the neutrons released during nuclear fission (the splitting of an atom's nucleus) successfully trigger at least one more fission. India currently relies predominantly on Pressurised Heavy Water Reactors (PHWRs), which use natural uranium and require a moderator (a medium that slows down neutrons to sustain fission). However, PHWRs are highly inefficient, utilizing only about 1% of the fuel. In contrast, a Fast Breeder Reactor (FBR) relies on fast-moving neutrons without a moderator and 'breeds' more fissile material than it consumes. In the , a core of plutonium is surrounded by a blanket of depleted uranium, which fast neutrons transmutate into more plutonium fuel. Uniquely, the PFBR uses liquid sodium as a coolant, which provides highly efficient heat transfer but reacts violently with air and water, necessitating stringent safety protocols. For UPSC Prelims, candidates must clearly differentiate between reactor types, their respective fuels, moderators, and coolants.
Economic & Energy Security
India's strategic pursuit of nuclear energy is dictated by its geography: it possesses modest uranium reserves but holds some of the world's largest deposits of thorium. To achieve long-term energy independence, physicist Homi Bhabha conceptualized the three-stage nuclear programme. Stage 1 utilizes natural uranium in PHWRs to produce electricity and plutonium. Stage 2 uses FBRs, fueled by the Stage 1 plutonium and depleted uranium, to breed even more plutonium. Finally, Stage 3 will deploy advanced reactors fueled by this accumulated plutonium alongside India's abundant thorium. The success of the is the critical bridge required to reach Stage 3 and establish a closed fuel cycle (where spent nuclear fuel is continuously reprocessed and reused). From a Mains perspective, mastering this closed cycle is indispensable for India's long-term energy security and its international commitments to achieve Net Zero emissions by 2070, especially as a reliable baseload power alternative to intermittent solar and wind energy.
Governance
The administrative structure governing India's nuclear sector presents a unique case study in public sector management and strategic autonomy. The operates with significant insulation, reporting directly to the . This institutional design has historically protected strategic nuclear projects from political volatility and allowed India to sustain complex scientific endeavors across different electoral cycles. However, this lack of standard public scrutiny has concurrently bred severe accountability deficits and project mismanagement. The PFBR, executed by , saw its initial budget balloon from ₹3,500 crore to ₹6,800 crore, suffering over two decades of missed deadlines. The project now awaits rigorous safety clearances from the before commercial operations can begin. For GS Paper 2, this scenario highlights a classic governance dilemma: balancing the necessity of strategic autonomy in sensitive sectors with the imperative of financial transparency, timely project execution, and strict regulatory oversight.