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Lead is essentially useless as a shield for neutrons that are below the minimum excitation energy of a lead nucleus. Elastic neutron collisions with lead leave
by pfdietz 1y ago
Lead is essentially useless as a shield for neutrons that are below the minimum excitation energy of a lead nucleus. Elastic neutron collisions with lead leave the neutron energy essentially unchanged.
- hunterpayne 1y agoI assume this is why an alloy of lead is used in practice. Still doesn't change the fact that graphite is a moderator not a shielding material. Also, structural materials in reactors are usually invisible to neutrons and a sandwich of materials is often used. Different layers do different things. Usually, one layer of shielding and one layer of a material that isn't impacted (much) by neutron flux for structural strength. There is a rabbithole for almost all of these material choices, especially in nuclear. Not going down that rabbithole in a discussion targeted at folks who don't spend their lives working in nuclear doesn't make that person wrong. It makes them an effective communicator. PS Lead is a very very common shielding material in nuclear.
- pfdietz 1y agoA moderator is a neutron shielding material, since it removes energy from the neutrons. That's what moderation is all about. Water is a much better moderator, but graphite still performs the function.