How non-radioactive objects become radioactive after the contact with the source of radiation?


HBO’s Chernobyl-related question. There are radioactive elements in nature. They are unstable and thus constantly radiating particles. But what exactly happens when those particles hit non-radioactive object like human body or whatever else? Isn’t they supposed to interact with it somehow and then fly away instantly? Why and how, instead, objects can harvest those particles, keep them and then re-radiate them over long period of time, and, thus, become radioactive?

In: Physics

The objects do not become radioactive. They get radioactive material on them, which continues being radioactive. When there’s a meltdown, the nuclear fuel itself gets spread over everything in fine particulate form or as a gas or liquid, and then sits there still being radioactive.

Imagine an open bag of flour in your kitchen, which you accidentally knock over. Most of the flour will still be on your kitchen counter, but some flour will become airborne. Anyway it will be a mess, and if you don’t clean up immediately you will end up with a kitchen where flour will end up everywhere.

The flour spreads by contamination. It does not turn other materials into flour, but it will stick to other materials or might become airborne. Anyway, it has a tendency to spread around and will continue to spread around.