This idea of having to store stuff for 100K years is so fantastically ridiculous that I can't really believe anyone takes it seriously.
Almost 400 years ago, the Swedish king Gustaf II Adolf planted oak trees outside of Stockholm, with the expressed intent that they were to be used as war ships in the twentieth century. The oaks are still standing. They are nice and everything, but it's sort of laughable to imagine that they will be cut down for war ships. Still, when he lived, the difference between life then and life 400 years earlier wasn't all that dramatic.
This is of course completely different now. We can be *extremely* certain that we will be able to either use the remaining energy in the nuclear "waste" or dispose of it in a completely safe way in the next 100 years (or, heaven forbid, that we blow up the planet entirely, in which case the point is pretty moot). The probability that none of that happens, civilization disappears, then reappears in some form in 50,000 years, and that they are able to dig up the buried waste, but can't read warning signs and don't have Geiger cuonters or similar instruments is almost as close to 0% as it is possible to get.
If that is your best argument against nuclear power, you have nothing to stand on. Nothing.