PHWR: India’s Indigenous Nuclear Reactor Technology Explained

Subject: GS Paper 3: Science and Technology

Context: India aims to expand civil nuclear power capacity to 100 GWe by 2047.

• With greater private participation in the nuclear sector, companies are initially preferring India’s indigenous Pressurised Heavy Water Reactors (PHWRs).

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About PHWR

• The pressurized heavy-water reactor (PHWR) is a type of nuclear reactor that uses heavy water (deuterium oxide, D2O) as its coolant and neutron moderator
• Key Features Of PHWRs: 
  • Pressure Tubes: Unlike many conventional reactors with a large pressure vessel, PHWRs use individual pressure tubes that contain the fuel and coolant.
  • Natural Uranium Fuel: PHWRs can use natural uranium, reducing dependence on uranium enrichment.
  • Heavy Water Moderator: Heavy water slows down neutrons while absorbing relatively few of them, improving neutron economy.
  • Refueling: PHWRs can be refueled during operation, avoiding the need for frequent long shutdowns.

Why Are PHWRs Preferred in India?

• Proven Technology: The current design of the 700 MWe PHWR is approved, operational, and already established in India.
  • Its technological maturity reduces risks associated with deploying an entirely new reactor technology. 
• Indigenised Supply Chain: Around 90–95% of the supply chain is indigenised, reducing dependence on external sources.
• Mature Ecosystem: India has an established network of vendors, technical expertise, and supporting infrastructure.
• Cost Advantage: PHWRs are currently considered the cheapest available nuclear power technology in India.
• Fleet Deployment: The established design and ecosystem make 700 MWe PHWRs suitable for fleet-mode deployment.
  • Repeated deployment of a standardised design can reduce construction time, costs and project risks through economies of scale. 

Strategic Significance For India

• Energy Security: Nuclear power provides a reliable source of electricity with low operational carbon emissions.
• Low-Carbon Transition: Expansion of nuclear energy can complement renewable energy to reduce dependence on fossil fuels.
• Energy Security Through Indigenous Technology: Indigenous PHWR technology reduces dependence on foreign reactor designs and technology.
• Domestic Industrial Development: Large-scale nuclear expansion can strengthen Indian manufacturing, engineering and specialized supply chains.
• Long-Term Nuclear Program: PHWRs form an important part of India’s indigenous nuclear power program and provide the technological base for its future nuclear expansion.

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Key Concern

• Dependence on Natural Uranium: Although PHWRs do not require enriched uranium, they require a reliable supply of natural uranium.
• Heavy Water Requirement: Heavy water is expensive to produce and maintain, increasing the complexity of the reactor system.
• Pressure Tube Integrity: PHWRs use numerous pressure tubes that operate at high temperatures and pressures and require regular inspection and maintenance.
• Ageing Of Reactors: Existing PHWRs require aging management and periodic refurbishment to maintain safety and efficiency.
• Limited Economies of Scale: The 700 MWe design is smaller than some large reactors being deployed globally, which can affect economies of scale.

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