Maybe ten(?) years ago, there was a big kerfluffle about some hunters in Siberia who got radiation poisoning after they snuggled up to an aircraft navigation
beacon on a mountaintop during a cold spell in the winter. Apparently....the Soviets had deployed remote
isolated beacons powered with a strontium pile, a practical way to make power for long terms far off the grid. Except, as best anyone could tell? They deployed 2000 of them and could only account for 200 of those.
So somewhere out there, should be about 1800 handy portable nuclear power sources, ripe for the taking. Never did hear a follow-up, apparently when the USSR collapsed, some things were no longer anyone's job.