Nuclear Reactors
Science & Technology
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Version 1Updated 10 Mar 2026
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Nuclear reactors are fundamental to harnessing atomic energy, serving as controlled environments for sustained nuclear fission reactions. These complex engineering marvels convert the immense energy released from splitting heavy atomic nuclei into thermal energy, which is then typically used to generate electricity. Globally, their design and operation are governed by stringent international safet…
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- POWER — Mnemonic: P-Pressurized systems, O-Ordinary/heavy water, W-Water cooling, E-Enrichment levels, R-Reactor control.
- Fission: — Splitting heavy atoms (U-235) for heat.
- Core Components: — Fuel, Moderator, Coolant, Control Rods, Containment.
- Moderators: — Heavy Water (PHWR), Light Water (PWR/BWR), Graphite.
- Coolants: — Light Water, Heavy Water, Liquid Sodium (FBR), Gas.
- Control Rods: — Absorb neutrons (Boron, Cadmium).
- India's Backbone: — PHWRs (natural uranium, heavy water, online refueling).
- Second Stage: — FBRs (breed Pu-239, liquid sodium coolant, Kalpakkam PFBR).
- Third Stage: — AHWR (thorium-based, passive safety, BARC design).
- Kudankulam: — Russian VVER (PWR) technology.
- SMRs: — Small, modular, enhanced safety, flexible deployment.
Vyyuha Quick Recall Mnemonic: POWER
- P — Pressurized systems (e.g., PWR, PHWR keeping coolant under pressure)
- O — Ordinary/heavy water (distinction between light water and heavy water as moderator/coolant)
- W — Water cooling (most common coolant, but also liquid sodium for FBRs, gas for others)
- E — Enrichment levels (natural uranium, low-enriched, MOX, thorium-based fuel)
- R — Reactor control (via control rods and moderator adjustments)