Dave.

That’s better, but it’s still a mystery. Cs-137 sources should be rigorously stored, even in density gauges they are permanently inside a capsule with a shutter that turns the beam “on and off”. It’s not like you have a chunk of Cs-137 rattling around in a drawer somewhere (or worse, somehow in powered form that gets all over the inside of a shipping container) but that sounds like that’s been the case here.

It’s not the first time one of these sources has come loose though - there was a capsule lost on 1400km of highway in Western Australia a little while ago.

Cs-137 is used in industrial density gauges. You want to measure the density of a liquid in a pipe? A radioactive source on one side, a detector on the other, easy-peasy.

Now how the fuck a controlled substance escapes from its highly encapsulated and supposedly-well-tested-and-regularly-inspected compartment and gets into your food, well that’s something else to ponder.