India’s 3 Stage Nuclear Programme | Science & Technology for UPSC CSE PDF Download

India's 3-Stage Nuclear Programme

India’s three-stage nuclear power programme, envisioned by Homi Bhabha in the 1950s, ensures long-term energy security by leveraging limited uranium and abundant thorium reserves. By 2025, it advances energy independence, supporting India’s net-zero carbon goal by 2070 through a sustainable nuclear fuel cycle.

• Stage 1: Employs natural uranium-fueled Pressurized Heavy Water Reactors (PHWRs) to produce plutonium.
• Stage 2: Uses plutonium in Fast Breeder Reactors (FBRs) to breed uranium-233 from thorium.
• Stage 3: Deploys thorium-based Advanced Heavy Water Reactors (AHWRs) for sustainable energy.

Thorium's Potential:

• India holds ~25% of global thorium reserves, making it a strategic asset, despite complex breeding requirements.
• Thorium’s conversion to fissile uranium-233 is costlier than uranium but ensures long-term sustainability.

Current Research and Development

The Department of Atomic Energy (DAE) drives indigenous R&D for advanced nuclear systems, aligning with the three-stage programme. By 2025, India’s nuclear capacity is ~8,000 MW, with new 700 MW PHWRs at Kakrapar (Units 3 & 4) and Kudankulam (Units 3 & 4) operational. Nine reactors are under construction, and 10 more are approved for fleet-mode deployment by 2032. The 2025 Nuclear Energy Mission (₹20,000 crore) supports Small Modular Reactors (SMRs) and thorium research, with BARC advancing AHWR designs and pilot projects.

3 Stage Nuclear Programme

Understanding the 3-Stages of India’s Nuclear Program

The three-stage programme aims for nuclear self-sufficiency, utilizing India’s thorium reserves via a closed fuel cycle for sustainable energy. By 2025, it supports decarbonization and complements renewables, aligning with global nuclear resurgence.

Stage I: Employs Pressurized Heavy Water Reactors (PHWRs) using natural uranium-238 (U-238), containing uranium-235 (U-235) for chain reactions.

• PHWRs use heavy water (deuterium) to moderate neutrons, enhancing fission efficiency under pressure.
• Fission produces plutonium-239 (Pu-239) and energy, consuming U-235 fully.

Stage II: Utilizes Pu-239 with U-238 in Fast Breeder Reactors (FBRs) to generate energy and breed more Pu-239 and uranium-233.

• The Prototype Fast Breeder Reactor (PFBR) at Kalpakkam achieved core loading in March 2024 and criticality in 2025, a major milestone.
• The Bharatiya Nabhikiya Vidyut Nigam, Ltd. (BHAVINI), established in 2003, oversees Stage II, with plans for two additional FBRs by 2030.

Stage III: Employs Advanced Heavy Water Reactors (AHWRs) using thorium-plutonium fuels to breed uranium-233 (U-233) from thorium-232 (Th-232), with pilot projects underway by 2025.

Introduction to PFBR (Stage II)

• A breeder reactor generates more fissile material than it consumes, key to Stage II.
• In ‘fast’ breeder reactors, unmoderated neutrons enable specific fission reactions.

Role of PHWRs in Breeding:

• PHWRs use natural uranium-238 (U-238) to produce plutonium-239 (Pu-239) as a byproduct.
• Pu-239 is mixed with U-238 to create mixed oxide fuel for FBR cores, with blanket material breeding more Pu-239.
• Blanket material reactions yield additional Pu-239, enhancing fuel efficiency.

Coolant System in PFBR:

• The PFBR uses liquid sodium coolant in two circuits for heat transfer.
• Primary coolant absorbs heat and radioactivity, transferring heat to the secondary circuit via exchangers.
• Secondary coolant powers generators, producing electricity safely.

Use of Thorium in PFBR:

• Thorium-232 (Th-232) serves as a blanket material in PFBRs.
• Th-232, non-fissile, transmutes into fissile uranium-233 (U-233).
• U-233 fuels Stage III, enabling thorium-based energy.

Transition to Third Stage

• The PFBR bridges Stages II and III, producing U-233 for thorium-based AHWRs, leveraging India’s vast thorium reserves.

Future Plans for PFBR:

• The PFBR (500 MWe) achieved criticality in 2025, with commercial operations imminent.
• DAE plans two additional FBRs by 2030, supported by the 2025 Nuclear Energy Mission’s funding.

Reasons Behind the Delay of PFBR (Stage II)

• Post-1974 ‘Smiling Buddha’ sanctions forced FBTR to use mixed carbide fuel instead of enriched uranium, reducing output.
• Fuel changes altered FBTR’s operating conditions, complicating PFBR development.
• By 2003, PFBR’s start saw key FBTR team members retired, causing expertise gaps.
• A 2014 CAG audit criticized BHAVINI for over-relying on NPCIL for PFBR components.
• Technical issues with the sodium coolant system delayed progress.
• Costs escalated from ₹3,492 crore to over ₹6,800 crore, with criticality achieved in 2025.
• The Indira Gandhi Centre for Atomic Research (IGCAR) designed PFBR, overcoming delays with 2025 criticality.

Challenges Ahead for the Stage II of India’s Nuclear Program

• FBRs’ thorium fuel cycle produces radioactive isotopes (caesium-137, actinium-227, radium-224/228, thorium-230), complicating handling.
• The IAEA urged an independent regulator in 2015; the NSRA Bill remains under review in 2025, criticized for government control.
• The NSRA aims to replace the AERB, enhancing safety oversight.
• Nuclear power’s higher cost (~₹6/kWh) versus solar (~₹2.5/kWh) is offset by reliability and decarbonization benefits.
• The 2025 Nuclear Energy Mission promotes SMRs and PPPs to improve cost-efficiency and expand capacity, with NPCIL targeting one reactor commission annually.