Source: BS
Context: The Atomic Energy Regulatory Board (AERB) has granted operational licences to NPCIL for two indigenous 700 MWe Pressurised Heavy Water Reactors (PHWRs) at Kakrapar Atomic Power Station (Units 3 & 4) in Gujarat.
About Pressurised Heavy Water Reactors:
- What is a PHWR?
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- A nuclear fission reactor that uses natural uranium as fuel and heavy water (D₂O) as both coolant and neutron moderator.
- Designed to operate with online refuelling, allowing continuous energy production.
- Developed By:
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- Initially with Canadian support (Rajasthan-1), later fully indigenised by BARC (Bhabha Atomic Research Centre) and NPCIL (Nuclear Power Corporation of India Ltd) under the Department of Atomic Energy.
- Historical Evolution:
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- RAPS-1 (1973): With Canadian collaboration.
- RAPS-2 onwards: Entirely developed by Indian scientists post-AECL withdrawal.
- Progression from 220 MWe → 540 MWe → 700 MWe with full domestic R&D and manufacturing.
- How Does It Work?
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- Uses heavy water as moderator to slow down neutrons and maintain a sustained chain reaction.
- Fuel rods (natural uranium) are inserted into pressure tubes within a calandria vessel.
- Hot pressurised heavy water carries heat to steam generators → drives turbines → generates electricity.
- Control rods and ECCS systems regulate power output and enhance safety.
- Key Features of 700 MWe PHWRs:
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- Fully indigenous design and operation, including construction, fuel fabrication, and control systems.
- Online refuelling system improves efficiency and reduces downtime.
- Equipped with twin fast-acting shutdown systems, double containment, and passive heat removal.
- Digital Instrumentation and Control Systems enhance real-time safety and automation.
- On-site heavy water moderation and cooling reduces external dependency and enriches neutron economy.
- Significance of Recent Licence:
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- Boosts India’s 10-reactor PHWR fleet mode rollout, part of its strategy to add 7000 MWe capacity indigenously.
- Confirms that India has mastered end-to-end nuclear tech from design to decommissioning.
