Fallout and radioactive contamination

This is a very basic post about fallout. Posts about defenses will come later.

Fallout is a familiar term that denotes the radioactive dust and debris that are sucked into the nuclear mushroom cloud at the point of detonation, and then descends back to earth from the air. It is carried about by winds aloft and 'falls out' in a swath downwind of the detonation site. The videos in this post, old as they may be, explain fallout quite well.



Link to video https://www.youtube.com/watch?v=yE-nji8-1Ko

I like the spooky, high tech music in this one.

Another kind of contamination that can fall back to earth is radioactive water, in the form of 'black rain' or as normal looking rainwater. In order for large amounts of contaminated water to pose a hazard, the bomb must have detonated either on or in water, such as a bay or lake, or near enough to a water source to convert large quantities of water into radioactive steam.



Link to video above: https://www.youtube.com/watch?v=4Cff_0bHVZA

Here you can see how concepts such as radiation had to be explained to general audiences in the 50's. This was all new to them. The 1950's fallout shelters were appropriate for the risks of the time, but not necessarily best for our time and our risks.

The Hiroshima bomb detonated right above a river junction which was the aim point of the drop. Survivors reported black rain falling not too long after the blast. In studies afterwards, it was shown that this black rain was far more damaging to human tissue than radioactive dust or particles. The problem with contaminated water is that it pervades all the places and parts of the environment that water usually does, while dust and debris can at least be washed away or brushed off. It also mixes with uncontaminated water.



Video link https://www.youtube.com/watch?v=pFddUOg4gQg&t=420s

The defense against particulate fallout is shelter, avoidance, and cleanup. These techniques are reasonably easy and don't require any special tools or methods. The best defense when water is contaminated is to have or get a clean water supply until such time as the radioactivity has worn off and regular supplies are safe to drink. Given the large quantities of water we humans need to live, this could be an acute problem.

In the atmospheric nuclear testing era of the 40's through the '60's, huge quantities of fallout were generated. The greatest proportion of it fell back close to the bomb site, but there was at least one known instance of accidental fatal contamination of a Japanese fishing crew from the 1954 Castle Bravo hydrogen bomb test in the South Pacific. Significant traces of radioactive substances from these tests drifted all around the world. I am old enough that my bones and teeth contain traces of the nuclear tests of the early Cold War.



Video link https://www.youtube.com/watch?v=1xjX_aoRUTQ

The bright spot here is that a terror device would be small and contamination problems would be mostly local. In the case of a dirty bomb,contamination could be quite severe in a localized area. So,in a terrorism scenario, there would be little or no fallout risk at distance. Of course, if the city that is bombed is your city, you would need to take action locally.