India’s 3 Stage Nuclear Programme | Science & Technology for UPSC CSE PDF Download

India's 3-Stage Nuclear Programme

• India's three-stage nuclear power programme, aimed at long-term energy security and sustainability using uranium and thorium, was proposed by physicist Homi Bhabha in the 1950s.
• Stage 1: Involves Natural Uranium-fuelled Pressurised Heavy Water Reactors (PHWRs).
• Stage 2: Fast Breeder Reactors (FBRs) using plutonium-based fuel.
• Stage 3: Advanced nuclear power systems for thorium utilization.

Thorium's Potential:

• India has about 25% of the global thorium reserves, making thorium an attractive option, despite its challenges.
• Thorium requires a breeding process to be used as fuel, which is currently more complex and costly than using uranium.

Current Research and Development:

• The Department of Atomic Energy (DAE) is conducting indigenous research and development for advanced nuclear power systems, in line with the three-stage programme.

Goal of the Programme:

• The three stages aim to make India self-sufficient in nuclear energy, leveraging its vast thorium reserves while gradually developing advanced nuclear technologies.

3 Stage Nuclear Programme

Understanding the 3-Stages of India’s Nuclear Program

• Stage I: In the first stage, India utilizes Pressurized Heavy Water Reactors (PHWRs) with natural uranium-238 (U-238) as the fissile material. U-238 contains only a tiny fraction of uranium-235 (U-235), which is the isotope capable of sustaining a chain reaction. 
  In PHWRs, heavy water, which is water containing the deuterium isotope of hydrogen, is used. Heavy water slows down the neutrons released during fission, allowing for more efficient reactions. To prevent heavy water from boiling, it is kept under pressure. The fission process in these reactors produces plutonium-239 (Pu-239) and releases a significant amount of energy. 
  Although only U-235 can sustain a chain reaction, it gets fully consumed in Stage I. 
• Stage II: In the second stage, India plans to use the Pu-239 produced in Stage I, along with U-238, in Fast Breeder Reactors (FBRs) to generate energy, uranium-233 (U-233), and more Pu-239. The Department of Atomic Energy (DAE) established a special-purpose vehicle in 2003 called Bharatiya Nabhikiya Vidyut Nigam, Ltd. (BHAVINI) to implement Stage II of the nuclear power programme. 
• Stage III: In the third stage, Pu-239 will be used in combination with thorium-232 (Th-232) in reactors to produce energy and U-233. This stage aims to further diversify and enhance India’s nuclear power capabilities. 

Introduction to PFBR (Stage II)

• A breeder reactor is a type of nuclear reactor that generates more fissile material than it consumes.
• In a 'fast' breeder reactor, the neutrons are not slowed down, enabling them to initiate specific fission reactions.

Role of PHWRs in Breeding:

•  Pressurized Heavy Water Reactors (PHWRs) utilize natural or low-enriched Uranium-238 (U-238) as the fissile material and produce Plutonium-239 (Pu-239) as a byproduct. 
•  This Pu-239 is then mixed with more U-238 to create a mixed oxide fuel, which is loaded into the core of a new reactor along with a blanket material. 
•  The blanket material reacts with fission products to produce more Pu-239. 

Coolant System in PFBR:

•  The PFBR uses liquid sodium, a highly reactive substance, as a coolant in two separate circuits. 
•  In the first circuit, the coolant enters the reactor, absorbs heat and radioactivity, and then transfers only the heat to the coolant in the secondary circuit via heat exchangers. 
•  The secondary coolant then transfers the heat to generators to produce electricity. 

Use of Thorium in PFBR:

•  Stage II of the PFBR program also envisions the use of Thorium-232 as a blanket material. 
•  Although Thorium-232 is not a fissile material, it will be converted into fissile Uranium-233 (U-233) through transmutation. 
•  This U-233 will be used as fuel in the third stage of the program. 

Transition to Third Stage

•  The PFBR thus serves as a crucial stepping stone towards the third stage of India’s nuclear program, facilitating the eventual full utilization of the country’s abundant thorium reserves. 

Future Plans for PFBR:

•  The PFBR has a capacity of 500 MWe. 
•  In 2019, the Department of Atomic Energy (DAE) proposed the construction of four more FBRs, each with a capacity of 600 MWe. 
•  These include two in Kalpakkam starting from 2021 and two additional FBRs from 2025 onwards, with specific sites yet to be selected.

Reasons Behind the Delay of PFBR (Stage II) 

• The FBTR was constructed in 1977, but the sanctions imposed on India following its 'Smiling Buddha' nuclear test necessitated the use of mixed carbide fuel instead of the enriched uranium that France was supposed to supply.
• This change in fuel type reduced the power output and altered the operating conditions of the reactor.
• By the time the Indian government initiated the PFBR project in 2003, many of the original team members from the FBTR were either nearing retirement or had already retired.
• A 2014 audit by the Comptroller and Auditor General (CAG) revealed that the Bharatiya Nabhikiya Vidyut Nigam (BHAVINI) had mishandled the procurement of several PFBR components by becoming too dependent on the Nuclear Power Corporation of India Limited (NPCIL)
• Other factors contributing to the delay included technical challenges related to the reactor coolant system.
• Consequently, the cost of the PFBR escalated to Rs 6,800 crore by 2019, with multiple extensions of the deadline. 
• The Indira Gandhi Centre for Atomic Research (IGCAR) in Kalpakkam designed the PFBR, with an original cost estimate of Rs 3,492 crore and a deadline of 2010.

Challenges Ahead for the Stage II of India’s Nuclear Program

• FBRs are harder to handle than other reactor designs. The thorium fuel cycle produces caesium-137, actinium-227, radium-224, radium-228, and thorium-230, which are all radioactive in ways that complicate their handling and storage.
• In 2015, the International Atomic Energy Agency (IAEA) urged India to set up an independent statutory atomic regulator instead.
• The DAE had responded with the Nuclear Safety Regulatory Authority (NSRA) Bill, which sought to replace the Atomic Energy Regulatory Body (AERB) with the NSRA.
• But it was criticised for allowing the Union government too much control over the NSRA’s composition.
• Today, the tariff for solar electricity is under Rs 2.5/kWh whereas nuclear electricity costs around Rs 4/kWh. The 2011 Fukushima Daiichi disaster also shifted public opinion worldwide against nuclear power, slowing work on new facilities.
• However, nuclear power has a new lease on life as a result of India's pressure to decarbonise, cut its fossil fuel imports, and give its renewables sector some breathing space. In 2023, NPCIL stated that it expects to "commission a nuclear power reactor every year" beginning in 2024.