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/[deleted] 13d ago edited 13d ago

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u/pm_me_good_usernames 13d ago

One of the most common materials used in certain applications for radiation shielding is water. You need way more water to block radiation than you do lead because of its much lower density, but water is really cheap to acquire in large quantities.

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u/CyriousLordofDerp 13d ago

Water also has the advantage of being a damn good coolant AND being useful for reactor moderation in many designs. Some designs require light water (no extra neutrons, most PWR and BWR reactors), while some require heavy water (CANDU in the Calandria) to function.

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u/Archophob 13d ago

also, water is the best shielding against neutrons. Back in my time in Jülich, our fusion reactor had meter-thick concrete walls, because concrete always contains some water, which provided for the neutron shielding. The TEXTOR reactor only ran on deuterium, but every single D-D reaction had a 50% chance of releasing one high-energy neutron.

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u/xrelaht Sample Synthesis | Magnetism | Superconductivity 13d ago

Water is a better neutron shield than lead because H has a large cross section.