I just don't get the problem, like at all. Dig a 5-6km deep shaft(we already have the technology for that depth, no issues), put the waste at the bottom. Keep drilling shafts until all waste is burried. That's far below the depth of any water sources, and unless you bury it near a tectonic fault, it's not making its way back through geological processes for eons. Like, can someone explain to me why we're not already doing that?
The deepest mine in the world is 4km deep. There are only a dozen or so more than 2km deep. Going down 5-6km may be possible, but definitely not with "no issues".
You don't need to drill tunnels for people to walk in - just a borehole wide enough to fit a cylinder filled with nuclear waste.
In fact, this very idea was already researched and test holes drilled - but of course was cancelled due to public opposition, even though we could get rid of our nuclear waste almost overnight using this method. Typical.
As per your Wikipedia article, current technology limits the borehole to 50 cm. That gets us 500 to 1000 m^3 worth of storage per borehole, assuming the lower 1km to 2km is used for storage.
From this[1] page, as far as I understand, on a global scale the current amount of nuclear waste in need of such storage is 482000 m^3. So roughly 500-1000 boreholes to store the current waste inventory.
Anyone got any ideas on how much it costs to drill a 5-6km 50cm hole?
As others have pointed out, most issues are political, not technical. There are already places which would be perfect(deep mine shafts surrounded by salt deposits, so they are literally impenetrable as salt is self-sealing) but the countries/states they are in object to keeping the waste as some sort of ideological issue.
What I want to know is whether there is a technical issue with what I am suggesting.
You just literally proposed to dig a 5-6m deep hole and assumed that would be enough...not even salt mines are enough. See Germany where there is suddenly groundwater seeking into a salt mine full of radioactive waste. A salt mine that was considered safe once. Now they are looking for years now to find a new safe spot and Germany stopped producing new waste. Still they have those problems. Tax payers are paying for this search. They'll also pay for the retrieval and they are paying for pumping out of the water.
There are many issues there obviously. This is not some easy thing you try to dig in there. It'll be there for a very long time.
My argument was also not aimed at the depth but at the unreflected "just dig a hole and hide it there" idea which reminds me of the dumping of nuclear waste into the sea.