eli5: Why is lead used as a radioactive shielding?
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It’s very dense so it’s pretty good at blocking radiation without having to be as thick as less dense materials. It’s also pretty darn cheap and easy to work with.
There are denser metals out there, but they tend to be significantly more expensive.
Lead is very dense and very cheap. You block radiation by having so much mass in the way that any particle or ray is sure to hit an atom and get bounced off or absorbed. Because of lead’s properties, it’s the most sensible material for putting a lot of big atoms between you and the radioactive source.
So “radiation” is just particles. Alpha, beta, gamma particles, depending on the kind of radiation. The likelihood of radiation hurting you depends on how clear a path exists between the radioactive “thing” and you. Particles are small. Traveling through things like air, there’s a good chance radioactive particles won’t hit anything between the thing and you. The more “stuff” there is between you and it the more chance those radioactive particles smack into something and don’t reach you.
Lead is *dense*. It’s very heavy. And particularly cheap. it makes a good shield because it’s made of a lot of “stuff” thus increasing the odds it impacts something between the thing and you.
Atoms block radiation. Lead has more atoms per square inch than most things at an affordable price
It has a very big nucleus, so it’s very likely that radiation will bump into it on its way passing through.
It’s also very common and cheap.
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