Prototype Fast Breeder Reactor (PFBR)

News: India achieved a major milestone in its civil nuclear programme as the 500 MWe Prototype Fast Breeder Reactor at Kalpakkam attained criticality, marking the start of a controlled nuclear chain reaction.

About Prototype Fast Breeder Reactor (PFBR)

• The Prototype Fast Breeder Reactor is India’s first fast breeder reactor, a nuclear reactor that produces more fissile material than it consumes using fast neutrons and plutonium-based fuel.
• Developed by: The reactor was indigenously developed by Indira Gandhi Centre for Atomic Research.
• Built by: It was built and commissioned by Bharatiya Nabhikiya Vidyut Nigam Limited.
• Operated by: It is operated by the BHAVINI under the Department of Atomic Energy (DAE).
• Working Mechanism of PFBR:
  • Fuel use: The reactor uses Uranium-Plutonium Mixed Oxide (MOX) fuel, where plutonium undergoes fission using fast neutrons.
  • Neutron process: Fast neutrons convert fertile Uranium-238 into fissile Plutonium-239, sustaining the chain reaction.
  • Breeding process: This conversion enables the reactor to produce more fuel than it consumes, which is the core principle of breeder reactors.
  • Coolant system: The reactor uses liquid sodium coolant, which efficiently removes heat and allows fast neutrons to persist.
  • Thorium pathway: The reactor is designed to use Thorium-232, which can be converted into Uranium-233 for the third stage.
• Key Features:
  • High fuel efficiency: It can extract more energy from uranium, improving resource utilization.
  • Support to nuclear programme: It acts as a bridge between Stage I and Stage III of India’s nuclear programme.
  • Closed fuel cycle: It enables recycling of nuclear materials, reducing waste.
  • Energy security role: It supports long-term clean and reliable base-load power generation.

About Criticality in Nuclear Reactors

• It is the stage where a nuclear chain reaction becomes self-sustaining and stable.
• Operational importance: It marks readiness of the reactor for power generation.
• States of Criticality:
  • Subcritical state: In this state, neutron losses are greater than production, so the chain reaction gradually dies out and the reactor shuts down.
  • Critical state: In this state, neutron production equals neutron loss, so the chain reaction becomes stable and self-sustaining, and power remains constant.
  • Supercritical state: In this state, neutron production exceeds losses, so the chain reaction increases rapidly, and reactor power rises.
• Safety aspect: Controlled criticality is essential for safe reactor operation.

About India’s 3 Stage Nuclear Programme

• It is a long-term strategy to achieve energy security using uranium and vast thorium reserves.
• Formulated by: It was formulated by Homi Bhabha in the 1950s.
• Aim: It aims to ensure energy independence, efficient fuel use, and utilisation of abundant thorium reserves.
• Three stages are:
  • Stage 1: Pressurised Heavy Water Reactors using natural uranium.
  • Stage 2: Fast Breeder Reactors using plutonium-based fuel.
  • Stage 3: Advanced systems using thorium to produce Uranium-233.