Burying radioactive waste in places unchanged for hundreds of millions of years is probably safe enough.

(Sadly, we have to consider that long because the current climate change is also unprecedented on these timescales.)

I am appalled though that anyone is seriously considering the idea of container-sized reactors, for which we can be nearly certain, if this seriously takes off, and we make million(s) of them, that hundreds if not thousands will end up abandoned in random places, and weathering will pierce them before they become radilogically inert.