BharatNotes Fission
noun (also occasionally verb, intransitive/transitive in technical use)Usage in a UPSC answer
India's case for an indigenous three-stage nuclear programme rests on harnessing controlled fission of its modest uranium reserves to breed plutonium, thereby converting a constrained fuel base into long-term energy security without compromising its strategic autonomy.
Synonyms
Antonyms
Word Family
fission (v), fissile (adj), fissure (n), fissionable (adj), fissility (n)
Root
Latin fissiō = a cleaving/splitting; findere = to split; -ion = process/result
Etymology
From Latin fissiō ("a cleaving, splitting"), from findere ("to split").
Memory Hook
Picture a "fish" being filleted down the middle into two halves: FISH-ion = a clean split into parts. The Latin root findere ('to split') also gives us "fissure", a crack or cleft.
How This Word Works in UPSC Writing
The splitting of a heavy nucleus into lighter ones with release of energy. The mechanism to state precisely is the chain reaction, since each fission releases neutrons capable of inducing further fissions, and whether the process grows, holds steady or dies out is described by the multiplication factor: below one the reaction dies out, exactly one is criticality and is the steady state a reactor maintains, and above one is supercriticality. Reactor control follows directly from this, with control rods of boron or cadmium absorbing neutrons to hold the factor at one, and a moderator such as heavy water or graphite slowing neutrons because slow neutrons are far more likely to induce fission in uranium-235. The distinction that matters for policy is that reactor fuel is enriched to a few per cent while weapons require far higher enrichment, so the same technology serves both purposes at different degrees, and that continuity is the whole of the proliferation problem.
Don’t Confuse It With
Fission splits a heavy nucleus while fusion joins light ones. Criticality means a multiplication factor of exactly one, a self-sustaining steady reaction, and is the normal operating state of a reactor rather than an accident or danger condition, which is a common misreading of news reports. A moderator slows neutrons to make fission more likely whereas a control rod absorbs them to regulate the rate, so their functions are opposite. Enrichment raises the proportion of fissile uranium-235, and reactor grade differs from weapons grade only in degree.
Hindi Meaning
विखंडन (vikhandan); मंदक (mandak) for moderator and नियंत्रक छड़ for control rod.
Common Questions
- What does criticality actually mean?
- That the chain reaction is exactly self-sustaining, with each fission producing on average one further fission. It is a reactor's normal operating state, not an emergency.
- What is the difference between a moderator and a control rod?
- A moderator slows neutrons so they are more likely to cause fission, while a control rod absorbs neutrons to slow the reaction down, so they work in opposite directions.
Seen in UPSC Question Papers
- Prelims 2024 — Physics
- Prelims 2024 — Space Technology
- Prelims 2024 — Space Technology
- Prelims 2016 — Nuclear Technology
- Prelims 2015 — Physics
Real UPSC previous-year questions whose text uses “Fission” — proof this word earns its place on your list.
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