It's worse than stumbling into a mine. Look up RTGs. They're nuclear batteries that have half lives of ~90 years that the USSR loved to sprinkle all over the woods when they couldn't be assed to maintain their own infrastructure for more than a few years. They were largely abandoned during the collapse, but hunters and scavengers still find these things and even drag them back to the village from time to time. Kills a few dumb villagers pretty bad every time it happens. There are more than 1000 of these things still out there, mostly unaccounted, and very few if any even have warning signs, let alone high security like a fence.