How far does nuclear fallout travel?

Nuclear fallout is defined as the residual radioactive ash that falls after some kind of nuclear disaster has happened. With that in mind, the spread of nuclear fallout can vary from episode to episode.

Chernobyl, for example, had a fallout radius of 30 kilometers, or 19 miles. In fact, it is still radioactive in most, if not all, of that original fallout radius. The fallout from the bomb dropped on Hiroshima had a fallout radius of about 1.6 kilometers, or 0.994 miles.

The previous answer gives a ton of details about how fast nuclear devices can go, so for a better idea of a universal value, see that answer as I cannot go into detail about that here.

Before I answer this question, it is best to define nuclear fallout first. It is the remaining radioactive material that is pushed into the atmosphere shortly after a nuclear blast. Now, the speed of a nuclear fallout will depend on the weather or the winds. Nuclear fallouts travel faster in stronger winds, and it also descends with the same time.

Nukes can travel at the speed of 13,000 miles per hour and a distance of more or less 67,000 yards away. Once it explodes, the nuclear fallout can travel as fast as 1,000 radii. People who are in 80 to 120 radii and 180 to 220 radius can still survive, but those who are within 270 radii up to 1,000 radii will definitely die.