Yucca Mountain was a bad site. Once they started digging they found that the ground was too loose. It wouldn't be able to support the weight without sinking. Have you ever seen the foundation of a house that sank on one side? The concrete buckles as the weight of the house slowly compacts the soil. The same thing will happen with millions of tons of waste, steel, and concrete. It's why missile silos were built in bedrock, not loose soil. Not to mention the technology wasn't going to allow digging deep enough to store all that much. It would mostly be used for waste from nuclear weapons, ship reactors, and other military projects. Not really that much space would have been available for commercial power generator use.

The conservatives who pushed for it did it because the contractors paid them to. It was blocked because the waste would leak not in thousands of years but in maybe decades. Not to mention the land was stolen from Native Americans and they didn't want nuclear waste in their stollen land. Among many other issues.

Edit: besides the Clintons have always been conservatives, too. So they're in that bucket. They're just moderates.

The problem is that by the 80s and 90s we were trying to wind down production of nuclear weapons as the cold war was winding down. Some of these reprocessing methods, like in France, reprocess the plutonium, and modern reactors just don't produce plutonium anymore. Also, some of the methods create uranium that is enriched to as much as 20%. With terrorism a big concern, that would be a pretty tempting target.

That being said, we are developing the tech, just very, very slowly. And now that renewables are cheap, it's just not necessary to have so many fueled generators. So the long term profit just isn't there for companies to want to invest. The area where I live is primarily hydro power, which is one of the more predictable renewables. But offshore wind farms give a pretty steady flow as well. And in deserts concentrated solar power can generate enough energy during the peak times when A/C is being used. And if there were better battery tech, more could be stored for use at night than currently is, and wind is still pretty reliable due to the changes in temperature from day to night.

Of course we still need fueled generators, but we shouldn't be expanding them, we should be concentrating on using them only as a backup to renewables.

Because all technology will require that. If we want energy, we have to build stuff. But there's no fuel to buy, generally much less ecological impact due to limited waste products since no fuel is being "burned". And the building cost is one time and generally subsidized, and maintenance is considerably lower, not to mention labor since you don't need nuclear specialists to run the day to day.