Yield
Overview
Nuclear yield measures a weapon’s explosive power in TNT equivalent, typically expressed in kilotons (thousands of tons of TNT) or megatons (millions of tons). This measurement quantifies the total energy release from nuclear fission and fusion reactions.
Units of Measurement
Nuclear yield uses standardized units:
- Kiloton (kt): Equivalent to 1,000 tons of TNT
- Megaton (Mt): Equivalent to 1,000,000 tons of TNT
- Energy release: 1 kiloton = 4.184 × 10¹² joules
- Comparison: Hiroshima bomb was 15 kilotons
Historical Examples
Major nuclear weapons demonstrate yield ranges:
- Little Boy (Hiroshima): 15 kilotons
- Fat Man (Nagasaki): 20 kilotons
- Castle Bravo: 15 megatons (expected 5 megatons)
- Tsar Bomba: 50 megatons (largest ever tested)
Modern Weapons
Current nuclear arsenals contain various yield ranges:
- Tactical weapons: 0.3-50 kilotons
- Strategic warheads: 100 kilotons to 1.5 megatons
- Largest deployed: Up to 25 megatons
- Efficiency: Modern weapons achieve 600-2,200 kt per ton of device weight
Yield Factors
Several factors determine nuclear yield:
- Fissile material: Amount and quality of uranium/plutonium
- Weapon design: Implosion efficiency and compression
- Fusion stage: Thermonuclear weapons add hydrogen fusion
- Tamper: Materials that reflect neutrons back into core
Weapon Types by Yield
Different weapons serve different purposes:
- Artillery shells: 0.1-1 kiloton
- Submarine missiles: 100-475 kilotons
- ICBMs: 300 kilotons to 1.2 megatons
- Gravity bombs: Up to 25 megatons
Scaling Effects
Yield affects damage in predictable ways:
- Blast radius: Scales with cube root of yield
- Thermal radiation: Scales with square root of yield
- Fallout area: Proportional to yield for surface bursts
- EMP effects: Increase with yield and altitude
Yield vs. Weight
Nuclear weapons show dramatic miniaturization:
- Early weapons: 4-15 kilotons per ton of device weight
- Modern weapons: 600-2,200 kilotons per ton
- Warhead size: MIRV warheads weigh 200-500 kg each
- Delivery efficiency: Higher yield-to-weight ratios enable multiple warheads
Relevance to Nuclear Weapons
Yield is crucial to nuclear weapons because:
- Determines the scale of destruction and casualties
- Affects weapon delivery requirements and targeting strategy
- Influences deterrence calculations and arms control treaties
- Scales weapon effects from tactical to strategic levels
Sources
Authoritative Sources:
- Nuclear Threat Initiative - Nuclear security analysis
- Atomic Heritage Foundation - Nuclear weapons history
- International Campaign to Abolish Nuclear Weapons - Disarmament advocacy
- Bulletin of the Atomic Scientists - Nuclear policy analysis