рдПрдХ рджреНрд░реБрдд рдкреНрд░рдЬрдирдХ рд░рд┐рдПрдХреНрдЯрд░ (рдПрдл рдмреА рдЖрд░) рдФрд░ рдПрдХ рддрд╛рдкреАрдп рдкрд░рдорд╛рдгреБрдХ рд░рд┐рдПрдХреНрдЯрд░ рдХреЗ рдмреАрдЪ рднреЗрдж рдмрддрд╛рдЗрдПред рдХрд▓реНрдкрдХреНрдХрдо рдореЗрдВ рд╕реНрд╡рджреЗрд╢реА рд░реВрдк рд╕реЗ рд╡рд┐рдХрд╕рд┐рдд рдкреНрд░рдердо рдкреНрд░рд╛рд░реВрдкреА (рдкреНрд░реЛрдЯреЛрдЯрд╛рдЗрдк) рдПрдл рдмреА рдЖрд░ рдХреЗ рд╕рдВрджрд░реНрдн рдореЗрдВ, тАШрдХреНрд░рд╛рдиреНрддрд┐рдХрддрд╛ (рдХреНрд░рд┐рдЯрдХрд▓рд┐рдЯреА)тАЩ рдкрдж рдХреА рд╡реНрдпрд╛рдЦреНрдпрд╛ рдХреАрдЬрд┐рдпреЗред рд╣рдорд╛рд░реЗ рджреЗрд╢ рдХреЗ рд╕реНрд╡рдЪреНрдЫ рдКрд░реНрдЬрд╛ рднрд╡рд┐рд╖реНрдп рдХреЗ рд▓рд┐рдпреЗ рдЗрд╕рдХреЗ рдирд┐рд╣рд┐рддрд╛рд░реНрде рдХреНрдпрд╛ рд╣реИрдВ ?
Read this question in English
Distinguish between a Fast Breeder Reactor (FBR) and a thermal nuclear reactor. In the context of first indigenously developed prototype FBR at Kalpakkam, explain the term тАШcriticalityтАЩ. What are its implications for clean energy future of our country ?
ЁЯзн How to think about this question ┬╖ directive: тАЬdistinguish / explain / whatтАЭ
Decode the demand
- Three directives, three parts: 'distinguish' asks for a point-by-point contrast of FBR and thermal reactor; 'explain' asks what criticality means, tied to Kalpakkam; 'what are its implications' asks for effects on clean energy, both promise and limits.
- The event in one line: India's first indigenous 500 MWe Prototype Fast Breeder Reactor attained first criticality on 6 April 2026, opening stage two of the three-stage programme.
- The trap: writing a general essay on nuclear energy. Each part needs its own heading, and criticality must be defined in physics terms, not as 'a milestone'.
Think in a structure
- Open with the dated fact and the three-stage programme, then turn to the contrast.
- Distinction as a table: neutrons, fuel, coolant, with a point on breeding; the table saves words and shows the examiner you know the mechanism.
- Criticality as a flowchart: from core loading to grid, so the term sits inside the real sequence at Kalpakkam.
- Implications in dimensions: fuel security, thorium bridge, climate targets, self-reliance, then caveats, each with a verified number where one exists.
- End positively: a way forward and Bhabha's vision as the anchor, linking 100 GW by 2047 to net zero by 2070.
Facts checked at source (5)┬╖ open
- DAE confirmed that the PFBR reached first criticality тАФ the start of a controlled fission chain reaction тАФ on 6 April 2026.Department of Atomic Energy тАФ PFBR attains first criticality (7 April 2026) тЖЧтАЬthe 500 MWe Prototype Fast Breeder Reactor (PFBR) has successfully attained first criticality (start of controlled fission chain reaction) on 6th April 2026тАЭ
- DAE explains that fast neutrons convert uranium-238 in the blanket into plutonium-239, so the reactor produces more fuel than it consumes.Department of Atomic Energy тАФ PFBR attains first criticality (7 April 2026) тЖЧтАЬFast neutrons convert fertile Uranium-238 into fissile Plutonium-239, enabling the reactor to produce more fuel than it consumes.тАЭ
- The PFBR is designed to eventually carry thorium-232 in its blanket, which transmutes into uranium-233 to fuel the third stage.DAE тАФ PFBR at Kalpakkam attains first criticality (April 2026) тЖЧтАЬThe reactor is designed to eventually use Thorium-232 in the blanket. Through transmutation, Thorium-232 will be converted into Uranium-233, which will fuel the third stage of IndiaтАЩs nuclear power pтАЭ
- Budget 2025-26 set a target of 100 GW of nuclear capacity by 2047.PIB backgrounder тАФ Nuclear Energy Mission, Union Budget 2025-26 тЖЧтАЬThe government has set an ambitious target of 100 GW nuclear power capacity by 2047, positioning nuclear energy as a major pillar in India's energy mix.тАЭ
- The Nuclear Energy Mission carries тВ╣20,000 crore for small modular reactor R&D, aiming at five indigenous SMRs by 2033.PIB backgrounder тАФ Nuclear Energy Mission, Union Budget 2025-26 тЖЧтАЬThe government has allocated тВ╣20,000 crore for this initiative, aiming to develop at least five indigenously designed and operational SMRs by 2033.тАЭ
Question: UPSC's CS (Main) 2026, GS Paper III тАФ paper тЖЧ. Guidance: Minimalist IAS, checked 8 Nov 2026 (how we verify). ┬╖
Model answer┬╖ 423words ┬╖ Minimalist IAS
On 6 April 2026 the 500 MWe Prototype Fast Breeder Reactor at Kalpakkam attained first criticality, the start of a controlled fission chain reaction. It opens stage two of Homi Bhabha's three-stage programme, and its value lies in how it differs from the thermal reactors India has run so far.
How an FBR differs from a thermal reactor
| Feature | Thermal reactor (PHWR) | Fast Breeder Reactor (PFBR) |
|---|---|---|
| Neutrons | slowed by a moderator, heavy water | fast, no moderator |
| Fuel | natural or enriched uranium | uranium-plutonium mixed oxide (MOX), uranium-238 blanket |
| Coolant | heavy water | liquid sodium; compact, high-power core |
- Breeding: fast neutrons convert fertile uranium-238 into fissile plutonium-239, so the PFBR produces more fuel than it consumes.
- Fuel use: a thermal reactor burns mainly the small uranium-235 fraction; a breeder taps abundant uranium-238, multiplying energy from the same ore.
The full answer goes on to cover
- 'Criticality' at Kalpakkam
- Implications for India's clean-energy future
- Way forward
With 1 flowchart you can reproduce in the exam.
Prepared by Minimalist IAS to the answer standard of Shivam Singh (mentor, 7 years) ┬╖ facts checked against official sources (how we verify) ┬╖ updated 8 Nov 2026. UPSC publishes no model answers: compare your structure and coverage with this, then write your own.







