India’s third home-built 700 MWe nuclear reactor achieves criticality

The nuclear power reactor that achieved criticality is the first of a new series of Pressurised Heavy Water Reactors (PHWRs) to be built at Rajasthan Atomic Power Project in Rawatbhata.

About

• 700 MWe units are the largest indigenous nuclear power reactors built by the Nuclear Power Corporation of India Limited (NPCIL), a public sector undertaking of the Department of Atomic Energy.
• These reactors are pressurized heavy water reactors (PHWRs), which use natural uranium as fuel and heavy water as coolant and moderator.
• The reactor achieved criticality after meeting the specified conditions of the Atomic Energy Regulatory Board (AERB), India’s nuclear safety regulator.

Nuclear Fission

• Nuclear fission splits a heavy atomic nucleus into two smaller nuclei, releasing energy through heat, light, and radiation.
• Radioactive atoms (or isotopes) are used in nuclear fission.
• Uranium-235 (U-235) and plutonium-239 (Pu-239) are commonly used isotopes for fission.
• U-235, a rare isotope of the heavy metal uranium, is the most commonly used nuclear fuel.

Nuclear Criticality

• • In nuclear reactor operation, criticality is the self-sustaining state of a nuclear chain reaction.
  • When there is a perfect balance between neutron production and loss rates, the nuclear system is considered critical.
  • During reactor startup, the neutron population is gradually increased in a controlled manner, ensuring more neutrons are produced than lost.
  • When the desired power level is achieved, the nuclear reactor is placed into a critical configuration.
  • Subcritical describes a nuclear system where neutron loss exceeds neutron production.
  • Supercritical describes a nuclear system where neutron production exceeds neutron loss.

NPCIL and its projects

NPCIL 

• The Nuclear Power Corporation of India Limited (NPCIL) is an Indian public sector undertaking based in Mumbai, Maharashtra.
• It is wholly owned by the Government of India and is responsible for the generation of nuclear power for electricity.
• NPCIL is administered by the Department of Atomic Energy (DAE).

NPCIL projects 

• NPCIL currently operates 24 reactors with a total capacity of 8,180 MWe and has eight units (including RAPP-7) with a capacity of 6,800 MWe under construction.
• In addition, 10 more reactors with a total capacity of 7,000 MWe are in pre-project phase and are expected to be completed progressively by 2031-32.

Series 

As per NPCIL RAPP-7 was the third in the series of 16 indigenous PHWRs of 700 MWe each being set up in the country.

Achieved projects 

Earlier, two 700 MWe PHWRs started commercial operation at Kakrapar Atomic Power Station (KAPS) in Gujarat.