4 ms·
Alpha radiation can’t penetrate the skin
by MagicMoonlight 4y ago
Alpha radiation can’t penetrate the skin
- littlestymaar 4y agoThis has nothing to do with alpha rays (which are helium nuclei), but with neutrons, and fast neutrons are much less prone to generate a fission than thermal neutrons, so having a moderator in between your fissile material parts reduces the amount of fissile material you need to achieve criticality. That's how nuclear reactor work, by the way. And this is also what happened to John Bistline on the 4th of June 1945 at Los Alamos. Edit: in fact the first ever recorded criticality accident ever recorded involved the water in the body of a scientist (Otto Frisch), though the water was acting as a neutron reflector here, and not as a moderator.