Why in news?
The Atomic Energy Regulatory Board (AERB) granted operating licences for two indigenously developed 700 MW pressurised heavy water reactor (PHWR) units at the Kakrapar Atomic Power Station in Gujarat. These are the largest reactors built in India and signify a leap in indigenous nuclear technology.
What is a PHWR?
- Unlike pressurised water reactors (PWRs) that use enriched uranium and ordinary water, PHWRs use natural (unenriched) uranium as fuel and heavy water (deuterium oxide) as both moderator and coolant.
- Heavy water slows down neutrons efficiently, enabling fission with natural uranium. This allows countries without uranium enrichment facilities to build nuclear reactors.
- PHWRs have on‑power refuelling. Fuel bundles can be replaced while the reactor is operating, improving utilisation and availability.
Evolution of India’s PHWR programme
- 1960s–70s: India built its first two 220 MW PHWRs at Rawatbhata (Rajasthan) with Canadian assistance. After Canada withdrew support following India’s 1974 nuclear test, Indian scientists indigenised the design.
- 1980s–2000s: Additional 220 MW units were built at Narora, Kakrapar and Kaiga. A 540 MW design was introduced at Tarapur.
- 2020s: Indian nuclear engineers developed a 700 MW Indian Pressurised Heavy Water Reactor (IPHWR‑700). Units 3 and 4 at Kakrapar became the first of this series to receive operating licences.
Features of the 700 MW PHWR
- Passive safety: Double containment structures, passive decay‑heat removal systems and partial boiling in the moderator ensure safety even during power failures.
- Economy of scale: Larger reactors produce more electricity with lower unit costs. Fleet mode construction will replicate the design across multiple sites, reducing costs.
- Indigenous supply chain: Most components, from heavy water to zircaloy tubes and control systems, are manufactured in India, reducing import dependence.
Significance
- Energy security: India aims to triple its nuclear power capacity by 2032 to meet growing electricity demand while cutting carbon emissions. PHWRs will form the backbone of this expansion.
- Strategic autonomy: Mastery of PHWR technology enhances India’s ability to pursue civil nuclear energy without relying on foreign fuel enrichment or reactor designs.
- Global outreach: With proven 700 MW designs, India may export PHWR technology to friendly countries seeking low‑cost nuclear power.