PFBR at Kalpakkam Attains Criticality

Recently, the indigenously developed Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, Tamil Nadu, successfully attained criticality, signifying a self-sustaining nuclear chain reaction. This milestone marks a significant leap forward in India’s long-pursued three-stage nuclear energy programme.

What is Criticality?

  • Criticality refers to the point at which a nuclear reactor sustains a self-sustaining fission chain reaction.
  • It indicates that the reactor core is functioning as designed and can now proceed toward full power operation and electricity generation.

India’s Three-Stage Nuclear Programme

India’s nuclear strategy, formulated by Dr. Homi Bhabha, aims to achieve energy independence by leveraging the country’s limited uranium but abundant thorium reserves (about 25% of global reserves). The programme unfolds in three sequential stages:

Stage 1: Pressurised Heavy Water Reactors (PHWRs)
  • Use natural uranium as fuel and heavy water (D₂O) as moderator and coolant.
  • Currently, PHWRs form the backbone of India’s nuclear power capacity, contributing 8,180 MWe.
  • India plans to expand this capacity to 22,400 MWe by 2032 through fleet-mode construction of multiple units.
  • Some PHWRs now use imported uranium and advanced fuels like HALEU (High-Assay Low-Enriched Uranium) to accelerate progress.
Stage 2: Fast Breeder Reactors (FBRs)
  • FBRs use MOX fuel (Mixed Oxide Fuel) — a blend of plutonium oxide and uranium oxide.
  • They are called “breeders” because they produce more fissile material than they consume by converting non-fissile U-238 into Pu-239.
  • This stage acts as a bridge to the third stage by generating plutonium, which is essential for breeding U-233 from thorium.
  • The 500 MWe PFBR at Kalpakkam is the first of its kind in India and is now in advanced commissioning.
  • Future plans include constructing six more FBRs of 600 MWe each, along with a dedicated fuel cycle facility.
  • Once fully operational, India will become the second country after Russia to operate a commercial-scale FBR. Many nations have abandoned FBR programmes due to high costs and safety concerns.
Stage 3: Thorium-Based Reactors
  • Focuses on using thorium (Th-232), a fertile material, which upon neutron irradiation, converts into fissile U-233.
  • India holds one of the world’s largest thorium reserves, primarily found in monazite sands along the coasts of Kerala, Tamil Nadu, Odisha, and Andhra Pradesh.
  • Thorium-based reactors promise long-term energy security, reduced dependence on imported fuel, and enhanced safety and waste characteristics.
  • Technologies under exploration include Advanced Heavy Water Reactors (AHWRs) and Molten Salt Reactors (MSRs).

Strategic Significance

  • The PFBR’s success strengthens Stage 2, enabling large-scale plutonium production for future thorium reactors.
  • It allows parallel development of thorium utilisation through technologies like thorium-based fuel in PHWRs, reducing waiting time for full FBR deployment.
  • Supports goals of energy independence, sustainable growth, and low-carbon energy transition.

Future Roadmap

  • Commissioning of PFBR and scaling up to commercial FBRs.
  • Development of thorium fuel cycle and associated reprocessing technologies.
  • Research into Generation IV reactors, including MSRs and fast reactors with enhanced safety.
  • Expansion of fuel recycling and closed fuel cycle infrastructure.

Constitutional & Policy Context

  • Governed by the Department of Atomic Energy (DAE), under the direct control of the Prime Minister’s Office.
  • India’s nuclear programme is civilian-focused but operates under a strategic autonomy framework due to its nuclear weapons status post-1974 and 1998 tests.
  • The Civil Liability for Nuclear Damage Act, 2010 regulates liability, though it has posed challenges for international reactor suppliers.

Source: The Indian Express