Protons, Neutrons & Morons
This is a lead container used to store a neutron source needed in some cased-hole logging applications. People try and steal this stuff all the time thinking they can make bombs out of it, or something really stupid like that. If they can haul off the container (its heavy as hell), break the locks and get the source out, to gawk at, they generally end up looking highly "energized," kind of like my old buddies, Alfalfa and Buckwheat.
So, don't mess around with neutron sources off logging trucks, o'tay?