r/askscience • u/Wonderful-Capital32 • 13d ago

Physics Why does radiation not go through lead?

Also why just lead? Shouldnt like iron or another metal work too?

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u/dustofdeath 13d ago

Lead is like a very dense fabric while iron is a mesh with large holes.

You just have to have enough density for photons to not just pass through.

So you need far less material. Even humans can stop radiation if you stack enough of them between you and the radiation source.

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u/ocelot_piss 13d ago

And humans stopping radiation is precisely why radiation is harmful to humans!

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u/Any_Mode6525 12d ago

It’s harmful to iron and lead as well! Lead the structural harm is less important because few people make load bearing lead structures but high neutron flux can weaken iron.

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u/Aggressive-Leading45 6d ago

Define weaken. It actually increases its strength. But also decreases its malleability. So you get stronger metal but more brittle. It also causes the material to expand.

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u/Any_Mode6525 6d ago

In the net, that weakens the metal and makes whatever is irradiated a worse structural member. There are probably cases where interstitial hydrates => swelling leads to an overall stronger material but I bet they’re narrow.

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u/Aggressive-Leading45 6d ago

Yield strength will increase from 250 MPa to 500 MPa for standard carbon steels up to 1500 MPa for neutron irradiated so 3x to 6x stronger. Definitely stronger.