[Nobido]

If the human race has persisted steadily enough over those 10000 years to have retained knoledge of our current languages, I doubt they would have let slide the knowledge of where the nuclear waste is buried.

I think the whole idea here is that a lot can happen in ten thousand years. Whoever is trying to go in there could be human or non human, could be advanced or primitive. Symbols are the best way to communicate in any of these events.

[electromagnetic]

The dark ages happened between us and the Roman Empire, but we still have their language, creative works, etc. However we don't know where their military caches were. Some things survive for longer simply because people care about some things more than others.

Yes symbols are the best way to communicate and a giant skull and crossbones is going to get most people to think "hey that's probably not good", but then the curse of the Pharaoh didn't stop everyone.

I personally prefer booby traps for keeping people out, but I don't think rigging a shotgun to a door handle would stay dangerous for 10,000 years with that whole rusting problem.