What's New :
7th July 2025 (11 Topics)

700 MWe PHWRs at Kakrapar

Context:

India's nuclear energy programme achieved a key milestone as the AERB granted a five-year operational licence to NPCIL for Units 3 and 4 of Kakrapar Atomic Power Station—India's first indigenously developed 700 MWe PHWRs.

Pressurised Heavy Water Reactor (PHWR)

  • A Pressurised Heavy Water Reactor (PHWR) is a nuclear reactor using natural uranium as fuel and heavy water (D?O) as both moderator and coolant.
  • Heavy Water Role: Deuterium (²H) in heavy water slows down neutrons without absorbing them—essential for fission in natural uranium.

Key Technical Features

  • Fuel: Natural uranium (U-238 and U-235); does not require enrichment.
  • Moderator/Coolant: Heavy water (D?O) used for both neutron moderation and heat transfer.
  • Design: Based on pressure tubes instead of a large pressure vessel (used in LWRs).
  • Heat Transfer Mechanism: Fission heat is transferred to a secondary loop to generate steam and drive turbines.

Working Principle

  • Chain Reaction: Neutrons are slowed by heavy water, enabling sustained fission in U-235.
  • Heat Generation: Resultant heat is absorbed by circulating heavy water.
  • Electricity Production: Heat is exchanged in a secondary circuit to produce steam for turbine-driven electricity generation.

Advantages of PHWRs

  • Use of Natural Uranium: Avoids costs and logistics of uranium enrichment.
  • Online Refueling Capability: Can be refueled without shutdown, increasing reactor uptime.
  • Fuel Versatility: Can operate using MOX fuel or thorium, supporting India’s thorium-based energy roadmap.
  • Economical Long-Term: Though heavy water is expensive, low fuel costs and efficient operation make it cost-effective over time.
Disadvantages
  • Heavy Water Cost: High cost for production, storage, and maintenance.
  • Design Complexity: Pressure tubes are prone to stress corrosion, requiring periodic inspection and replacement.
  • Safety Challenges: Although robust, pressure tube rupture poses a safety concern if not properly managed.
Global Deployment
  • India: Global leader in indigenous PHWR technology (e.g., Kakrapar 700 MWe reactors).
  • Canada: Developer of the CANDU (CANada Deuterium Uranium) PHWR design.
  • Other Countries: PHWR/CANDU variants used by Argentina, China, and South Korea.

 

Atomic Energy Regulatory Board (AERB):

Establishment & Legal Basis

  • Established: 15 November 1983.
  • Under: Atomic Energy Act, 1962.
  • Constituted by the Government of India to carry out regulatory and safety functions in the nuclear energy sector.
  • Administrative Control: Operates under the aegis of the Department of Atomic Energy (DAE), but functions independently in regulatory matters.

Mandate and Functions

  • Safety Oversight: Regulates the use of ionising radiation and nuclear energy for civilian applications.
  • Licensing Authority: Grants licenses for siting, construction, operation, and decommissioning of nuclear and radiation facilities in India.
  • Enforcement Power: Has authority to enforce compliance with safety standards and shut down facilities in case of violations.

Scope of Regulatory Activities

  • Nuclear Power Plants (NPPs): Safety regulation of design, construction, commissioning, and operation.
  • Radiation Facilities: Medical, industrial, and research usage of radiation sources (like X-ray units, cobalt therapy units).
  • Radiation Waste Management: Ensures safe disposal and containment of radioactive waste.
  • Transportation of Radioactive Material: Regulates packaging, transport, and handling of radioactive substances.

Organisational Structure

  • Chairperson: Appointed by the Government of India.
  • Committees and Advisory Bodies:

o   Safety Review Committee for Operating Plants (SARCOP)

o   Advisory Committee on Project Safety Review (ACPSR)

o   Radiological Safety Advisory Committee (RSAC)

  • These bodies support AERB with expert reviews and audits.

Safety Code:

  • Safety Codes: Formulates and enforces safety codes, standards, and guidelines.
  • International Coordination:

o   Collaborates with IAEA (International Atomic Energy Agency).

o   Participates in global nuclear safety conventions like the Convention on Nuclear Safety (CNS).

o   Aligns Indian safety protocols with international best practices.

 

Verifying, please be patient.

Enquire Now