That is simply untrue. The deepest operational facilities - e.g. Morsleben and Schact Asse II in Germany, WIPP in the US - are less than 1000m. There are a hand

That is simply untrue. The deepest operational facilities - e.g. Morsleben and Schact Asse II in Germany, WIPP in the US - are less than 1000m. There are a handful of others under construction, even more under consideration, but even if those all became operational today "regularly" at 4km would be a drastic overstatement. Even with the facilities that exist, there have been incidents and concerns about groundwater contamination over the truly long term that many of these isotopes require. You present it as a solved problem but in fact it's anything but.