Why Is PFBR Criticality in the News?
The Prototype Fast Breeder Reactor (PFBR) at Kalpakkam has achieved criticality – the start of the second stage of Indias three-stage nuclear programme. This makes India the second country after Russia to operate an FBR. A top-priority GS Paper 3 topic covered in depth at Riyasat IAS Mentorships UPSC Mentorship Program.
PFBR and Nuclear Programme – Key Facts for UPSC Prelims
| Term / Fact | Detail |
| PFBR | Prototype Fast Breeder Reactor – Kalpakkam, Tamil Nadu |
| Criticality | Chain reaction sustains itself – first step of commercial generation |
| PFBR status | India to be second country after Russia to operate FBR |
| FBR fuel | Pu-239 + U-238 (MOX) – produces more fuel than it consumes |
| PHWR fuel | Natural uranium (0.7% U-235 + 99.3% U-238) |
| FBR coolant | Liquid sodium (vs heavy water in PHWR) |
| Cost overrun | Rs.3,500 Cr to Rs.6,800 Cr; 2022 commercial target missed |
| Global failures | Japan Monju (1995 sodium leak), France Superphenix (closed) |
5 Critical Facts – PFBR and India Three-Stage Nuclear Programme
1. What Is Criticality?
Criticality is the state when the reactor chain reaction sustains itself – neutrons from one fission start at least one more fission. This is a stable state but only the first step towards commercial power generation, not the final milestone.
2. Difference Between FBR and PHWR
| Aspect | PHWR | FBR (PFBR) |
| Fuel | Natural uranium | Pu-239 + U-238 |
| Neutrons | Slowed (with moderator) | Fast (no moderator) |
| Coolant | Heavy water | Liquid sodium |
| Fuel efficiency | ~1% | 10%+ |
| Key feature | Produces Pu-239 as byproduct | Produces more fuel than it consumes |
3. Homi Bhabha Three-Stage Nuclear Programme
India has limited uranium but abundant thorium (~25% of world reserves). Homi Bhabha designed the three-stage programme in the 1950s – a direct UPSC question. Enrol in Secure Prelims Program 2026 to master it:
- Stage I: PHWRs using natural uranium -> electricity + Pu-239 + depleted U-238 [COMPLETE]
- Stage II: FBRs using Pu-239 + U-238 -> more Pu-239 + electricity. PFBR is its prototype [STARTING NOW]
- Stage III: Thorium-232 -> U-233 for electricity via AHWR [IN PROGRESS]
4. Major Challenges with PFBR
- Liquid sodium coolant reacts intensely with air/water – serious leak and fire risk
- Cost overrun: Rs.3,500 Cr to Rs.6,800 Cr; multiple timeline extensions
- Separate infrastructure needed for fuel reprocessing and AERB regulatory approvals
- High operational complexity and public opposition challenge economic viability
5. Way Forward
- Low power testing -> capacity ramp-up -> AERB commercial approval
- Construction of 4 EFBRs (500 MW each) at Kalpakkam
- Accelerate thorium-based AHWR; 100 GW nuclear capacity target by 2047
- SMR (Small Modular Reactors) and Nuclear Energy Mission (Rs.20,000 Cr investment)
- DAE: increase transparency, private participation in R&D, public awareness
UPSC Relevance – PFBR Criticality and Three-Stage Nuclear Programme
For Prelims:
- PFBR – full form, location (Kalpakkam, Tamil Nadu), criticality meaning
- Three-stage programme – Homi Bhabha, order of all three stages
- FBR vs PHWR – fuel, coolant, efficiency differences
- AERB – Atomic Energy Regulatory Board
- India thorium reserves – approximately 25% of world total
For Mains (GS Paper 3):
- PFBR criticality – technical, strategic and challenge dimensions
- Nuclear energy self-reliance – India roadmap
- Energy security and nuclear programme – national importance
- SMR and future of nuclear energy – policy analysis
For this quality of Mains preparation, join Riyasat Ali Sir UPSC Mentorship Program. The Essay Foundation Program builds analytical writing for S&T policy topics.
Practice Question (Mains – 250 words):
The achievement of criticality by PFBR at Kalpakkam marks the beginning of the second stage of India three-stage nuclear programme. Review the technical, strategic and challenge dimensions of this achievement.
Conclusion
PFBR criticality is a historic step towards Indias energy self-reliance and the foundation of Stage III thorium reactors. For complete command over S&T topics, join Riyasat IAS Mentorship. Apply for admission today.
Also Read:
- UPSC Mentorship Program – Riyasat Ali Sir
- Foundation Mentorship English
- Foundation Mentorship Hindi
- Secure Prelims Program 2026
- YATHARTH All India Mock Test
- Essay Foundation Program
- Current Affairs for UPSC
- 60 Days UPSC Preparation Results 2026
- FAQs – Riyasat IAS Mentorship
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