The biggest concern is that when things go wrong with nuclear, they really go wrong.

It is also a lot safer today if new reactors are built. The problem are the old reactors need to be shut down because they're based on older designs. We need to start building Pebble Beach reactors where even if there is a containment break, safe small carbon balls with a thin sliver of fissile material just spill out on the floor. These spread out and reduce their combined temperate averting a meltdown. Individually the balls themselves are not dangerous, they're lukewarm and could be held in the hand (not that you would). I think there are some even newer designs that go beyond this in safety. The problem with the anti-nuclear argument is that it is based on the old rod reactors like the one that failed in Fukushima prefect, Chernobyl or 3 mile island. Of course we shouldn't run those older models anymore. You need to start building the new safer reactors before you begin shutting down the old ones so you can logistically switch, however. Instead we're unfortunately heading for a future where we eventually just shut down these old reactors for safety without a real plan for replacing them. Or, we keep running the old models until they become the very cautionary tale that makes everyone nervous about nuclear.

Let's be fair: it's clean on the CO2 front, but the nuclear waste will be relevant for 100.000 years!

That is way, way longer than we have anything like civilization!