It's an absurd thought experiment to illustrate that even when taken to an extreme the volume is small enough that a solution broadly remains feasible.
In germany alone, 500 000 m³ of radioactive material is to be disposed somehow by 2050. Having people carry that underground sounds insane. There is more to waste than fuel rods. And even they .. amount to a really high number if you factor in shielding.
I think you have a serious misconception. The long term storage we're talking about here is for the spent fuel rods (or alternatively the byproducts extracted from them if they are reprocessed). It's known as high level waste and there isn't very much of it.
> As a general rule, short-lived waste (mainly non-fuel materials from reactors) is buried in shallow repositories, while long-lived waste (from fuel and fuel reprocessing) is deposited in geological repository.
> Overall, the 60-year-long nuclear program in the UK up until 2019 produced 2150 m3 of HLW.
