Third Indigenous Pressurised Heavy Water Reactor Attains Criticality: Advancing India’s Nuclear Power Capabilities

Third Indigenous Pressurised Heavy Water Reactor Attains Criticality: Advancing India’s Nuclear Power Capabilities

Sub : Sci

Sec: Nuclear sector /energy

Why in News:

India’s nuclear power sector made significant strides as Unit 7 of the Rajasthan Atomic Power Project (RAPP) achieved criticality. This marks a key milestone in India’s indigenous nuclear energy development.

Unit 7 of Rajasthan Atomic Power Project (RAPP) Achieves Criticality

Location: Rawatbhata, Chittorgarh district, Rajasthan.

Date of Criticality: September 19.

Significance of Criticality: Marks the start of a controlled fission chain reaction, a key step in the reactor’s operational phase.

Authority: The Atomic Energy Regulatory Board (AERB) had earlier granted approval for this critical phase.

Reactor Type: Pressurised Heavy Water Reactor (PHWR) of 700 MW capacity.

Series: RAPP-7 is part of a larger series of 16 indigenous PHWRs being developed by India.

Previous Achievements: The first two reactors to attain criticality in this series were Units 3 and 4 of the Kakrapar Atomic Power Station in Gujarat, which went critical in 2020 and 2023 respectively.

What is Criticality:  Criticality is the normal operating condition of a nuclear reactor, in which nuclear fuel sustains a fission chain reaction. A reactor achieves criticality (and is said to be critical) when each fission releases a sufficient number of neutrons to sustain an ongoing series of nuclear reactions.

India’s Three-Stage Nuclear Power Programme: India’s three-stage nuclear power programme was formulated by Homi Bhabha in the 1950s to secure the country’s long term energy independence, through the use of uranium and thorium reserves found in the monazite sands of coastal regions of South India.

Stage 1- Pressurized heavy water reactor (PHWR): The first stage involved using natural uranium to fuel PHWR to produce electricity and Plutonium-239 as a byproduct.

• Also, the byproduct plutonium-293 would be used in the second stage.

A Pressurised Heavy Water Reactor (PHWR) is a type of nuclear reactor that uses heavy water (D₂O) as both a moderator and coolant. It typically uses natural uranium as fuel, allowing it to operate without enriched uranium. PHWRs are known for their efficiency in utilizing fuel and can be refuelled while running.

Stage 2- Fast breeder reactor (FBR): The second stage involves using plutonium-239 to produce fuel, which would be used in Fast Breeder Reactors. Plutonium 239 undergoes fission to produce energy. Once a sufficient amount of plutonium-239 is built up, thorium will be used in the reactor, to produce Uranium-233. This uranium is crucial for the third stage.

Stage 3- Advanced Heavy Water Reactor (AHWR): The main purpose of stage-3 is to achieve a sustainable nuclear fuel cycle.

The advance nuclear system would be used a combination of Uranium-233 and Thorium.

Thorium absorbs the neutrons, which can more efficiently produce more Plutonium in Fast Breeder Reactor for a faster growth.

Difference Between Nuclear Fission and Nuclear Fusion