Originally Posted by
Consol
Lots of radiological incidents globally (some fatal) caused by incompetent managers generally in health care settings. Cobalt isotope sources and the like not being tracked and properly decommissioned and ending up in scrap or bring 'salvaged' and ending up the same way. Quite easy to see how low level substances could end up mixed with others although scrap metal is not transported by air unless of extremely high value.
They were probably looking for beta or neutron emissions, which do not define the emitter but do indicate there is radioactive material. Alpha doesn't penetrate much at all.