Heat Blast Radiation Fallout

Nuclear fallout would cause casualties far from the scene of the explosion.

Fallout is formed from material in the immediate area of the explosion which is vaporised, drawn up by the mushroom cloud and then dispersed downwind. It includes a range of radioactive iosotopes.

The fallout problem is much worse if the fireball touches the surface, which is called a "Groundburst" explosion. This occurs if the bomb is detonated on the ground, or close to the ground. In this case a large amount of material is vaporised.

If the bomb is detonated higher, in an "Airburst" explosion, the amount of material which is vaporised is smaller.

Fallout from a ground burst bomb is dispersed downwind from ground zero. There would be high radiation levels which could result in 25 per cent fatalitites in the affected area between 4 and 10 kms downwind. The fallout would be a significant problem more than 100 kms downwind. Fallout would be concentrated in places where it rained as the cloud passed over.