Context: A fiery exchange erupted in Rajya Sabha when Congress MP Jairam Ramesh questioned the progress of phase 2 of the nuclear programme of India, the status of the fast breeder reactor in Kalpakkam, and the plans for setting up thorium reactors for Phase 3.

Meaning of the context: India’s nuclear journey began shortly after Independence with the establishment of the Atomic Energy Commission in 1948. In 1956, Asia’s first research reactor, Apsara, was commissioned at the Bhabha Atomic Research Centre (BARC) in Trombay. India was the second Asian nation to build a nuclear power plant in 1969 at Tarapur, just after Japan and long before China. 

Key Takeaways:

• India owes the vision of the three-phase programme of nuclear power to ensure energy security to Dr Homi J Bhabha, the father of India’s nuclear programme, and Dr Vikram Sarabhai, who recognised the need for developing Fast Breeder Reactor (FBR).

Three-stage nuclear programme

Stage I: Pressurised Heavy Water Reactors (PHWRs)

• Fuel and Operating Principle: In the first stage, India relies on Pressurised Heavy Water Reactors that use natural uranium as fuel.
• Key Characteristics: These reactors utilize heavy water (deuterium oxide) as both a moderator and coolant, allowing them to efficiently sustain the nuclear chain reaction with low-enriched fuel.
• Outcome: A byproduct of this stage is the production of plutonium-239 in the spent fuel, which is essential for the next phase of the programme.

Stage II: Fast Breeder Reactors (FBRs)

• Role of Plutonium: Stage II capitalizes on the plutonium produced in Stage I. Fast Breeder Reactors use a mix of plutonium and natural uranium in a process known as “breeding.”
• Breeding Process: These reactors are designed to generate more fissile material than they consume. Fast neutrons (without slowing by a moderator) convert the fertile uranium-238 into additional plutonium, thereby increasing the fissile inventory.
• Objective: The goal is to build up a significant stock of fissile material that will bridge the gap between the limited uranium resources and the future utilization of thorium.
• Implementation Status: The Prototype Fast Breeder Reactor (PFBR) at Kalpakkam is a critical milestone in this stage, although its progress has faced delays.

Stage III: Thorium-Based Reactors

• Rationale for Thorium: India possesses one of the world’s largest reserves of thorium (approximately 25% of the global share), but only limited uranium resources. Thorium-232, which is not fissile in its natural state, needs to be converted (or “bred”) into uranium-233 through neutron irradiation.
• Reactor Development: The final stage envisions advanced thermal breeder reactors—such as Advanced Heavy Water Reactors (AHWRs) and other concepts like molten salt reactors—that utilize a thorium–uranium-233 fuel cycle.
• Long-Term Vision: Once the necessary fissile material has been accumulated in Stage II and the technology for breeding uranium-233 from thorium is perfected, India aims to achieve sustained nuclear power generation that relies primarily on its abundant thorium resources.
• Impact: This stage is expected to drastically reduce dependence on imported uranium and pave the way for a self-reliant nuclear energy programme lasting for centuries.

Source : Indian Express