Colombo city centre sits 274.2 km from Kudankulam Nuclear, India, the most plausible strategic target in the area (low targeting confidence). Modelled strike: 100 kt surface burst.
Estimated survival chance at city centre: 99%
What a strike on Kudankulam Nuclear, India would mean
A 100 kt detonation produces a fireball 479 m across in radius. Reinforced concrete fails out to 1.3 km (20 psi). Most residential buildings collapse within 2.6 km (5 psi), and windows shatter dangerously out to 5.8 km (1 psi). Anyone in line of sight within 4.4 km suffers third-degree burns from the thermal pulse.
Because military and hardened targets are typically attacked with surface bursts, fallout matters here: with prevailing winds the dangerous plume would stretch roughly 52 km east of ground zero. Colombo city centre lies outside the projected corridor under these wind assumptions.
Most plausible targets near Colombo
| Target | Type | Distance | Assumed yield | Confidence |
|---|---|---|---|---|
| Kudankulam Nuclear, India | energy | 274 km | 100 kt | low |
| Mumbai (BKC financial) | city | 1547 km | 300 kt | medium |
| Diego Garcia | military | 1786 km | 300 kt | medium |
| Bangkok | city | 2380 km | 150 kt | low |
| Karachi port & industry | port | 2417 km | 150 kt | medium |
Key blast radii (100 kt surface burst)
| Effect | Radius | What happens |
|---|---|---|
| Fireball | 479 m | Complete vaporisation |
| 20 psi blast | 1.3 km | Hardened structures destroyed, ~100% fatalities |
| 5 psi blast | 2.6 km | Most buildings collapse, widespread fatalities |
| 3rd-degree burns | 4.4 km | Full-thickness burns to exposed skin |
| 500 rem radiation | 1.9 km | Lethal dose without medical care |
| 1 psi blast | 5.8 km | Window breakage, light damage, glass injuries |
How Colombo can prepare
With a population density of 3,400 people/km², Colombo's outcome would hinge on the first hour. The guidance is identical everywhere: get inside, stay inside, stay tuned. A basement or the core of a large concrete building cuts fallout exposure by a factor of 10 or more, and radiation decays fast — dose rates fall ~90% within the first 7 hours and ~99% within two days.
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