Nuclear is a hot topic on HN and its dangers are often compared to pollutants from solar plants, etc. But these comparisons simply cannot be made and here's why.
The matter that makes up our world, including chemcials, heavy metals, drugs, and other poisons operates at the molecular level. To be poisoned, you must ingest them or make contact with your skin.
Radiation, however, operates below that, at the subatomic level. It results when an atom has an unstable internal arrangement. Radioactive elements continually shed particles which contact or pass through other materials at a distance.
The most powerful and dangerous kind, gamma radiation, is emitted by plutonium, a byproduct of all nuclear power generation. Gamma particles have enough energy to pass through your body and into other objects.
Gamma radiation is powerful enough to damage DNA chains and disrupt cell growth, which is how it creates cancers and congenital disorders.
When a gamma particle hits other kinds of matter, it can cause that matter to also become unstable and begin shedding particles. This is how materials become radioactively contaminated.
Lead is toxic, but you can hold a toxic amount of lead in your hands and experience no ill effects. Lead doesn't "reach out" into space and begin hurting people at a distance, and it doesn't turn other materials into toxins.
It is this fundamental difference between subatomic particles which travel of their own accord, penetrate other materials, and turn them toxic that separates radioactive hazards from every other kind of danger.
And now you know.
BTW, the reason lead is used as a radioactive shield is that it's too dense to allow many gamma particles to penetrate. Atoms are internally "quantized" with only certain spots open for penetration, and lead has the fewest of these. It's not totally impervious, however, which is why nuclear medicine and nuclear plant operators receive higher doses than the general population.
> When a gamma particle hits other kinds of matter, it can cause that matter to also become unstable and begin shedding particles. This is how materials become radioactively contaminated.
No, totally no. You can irradiate something with gamma radiation, and it will not become radioactive. Moreover, it is a standard method to preserve some food, because a big dose of radiation kills the bacteria (and everything else) but the food is totally safe to eat later. https://en.wikipedia.org/wiki/Food_irradiation
> BTW, the reason lead is used as a radioactive shield is that it's too dense to allow many gamma particles to penetrate. Atoms are internally "quantized" with only certain spots open for penetration, and lead has the fewest of these. [...]
Also no. The part about the "spots open for penetration" is totay wrong. Lead is a good shield against gamma radiation because it is very dense and each atom has a lot of electrons, so a fixed volume has more electrons than most other material. Gamma rays "bounce" against the electrons and the energy is split, and after a few splits each part is not dangerous. https://en.wikipedia.org/wiki/Lead_shielding