> DROPPING barrels in an abandoned mine for final storage, just to find out it does not only totally leak, but advisors precisely warned about it beeing not a suitable location

And this is a massive political issue with which the Green parties collect millions of votes. Meanwhile "of 265 US power plants that monitor groundwater, 242 report unsafe levels of at least one pollutant derived from coal ash" - so instead of the small potential of ground water contamination from a small number of nuclear plant waste barrels, people passively chose the almost certainty of ground water contamination by leachate containing arsenic, barium, beryllium, boron, cadmium, nickel, lead, mercury, molybdenum, selenium and thallium - a chunk of it radioactive.

But it got votes.

Maybe that's the biggest problem, really.

The design, deployment, regulatory/political hurdles, and the long operational lifetime of nuclear power plants, make that any improvements take a loooonng time to bear fruit.

Inertia of the installed base with its problems (and history), makes new development near-impossible.

That situation propably won't improve until newer designs accumulate a multi-decade track record of safety, or fusion power gets commercialized.