Nuclear isn’t great long term, but of all the options that aren’t great long term, nuclear is the least not great. It can support the backbone of the energy grid for relatively cheap and in much safer conditions than other energy sources, even if we are led to believe otherwise by Chernobyl and Fukushima. Advances in nuclear reactor technologies means nuclear becomes safer and more maintainable over time, and it already has been the safest source of energy for a while. Also, Japan doesn’t shy away from nuclear; they’ve designed systems that heavily recycle nuclear waste to extract as much energy from it as possible, which also has the added effect of reducing the waste’s radioactive life.

It’s simple, really. We rely on it to support us while fusion gets off the ground, and even if it doesn’t get off the ground, we can still rely on fission to support us while we get more and more renewable sources up and running.

If anything it’s the fear of nuclear that’s been keeping us in such bad energy situations. For instance, France, being at the forefront of nuclear energy use, has not worked on new reactors up until recently after decades of underfunding and underdevelopment. Now the lack of maintenance and develoent of new reactors means that old reactors have begun showing signs of significant wear and tear, threatening the entire grid and part of the French economy; they’re energy exporters (green energy, at that), but are years away from having to phase out old reactors and become energy importers. That imported energy is almost guaranteed to be sourced from fossil fuels. If not even these nations are enticed to keep nuclear up and running, how are we ever to leave fossil fuels?

As for your mining comment, we’re going to have this issue even if we were to rely mostly on renewable. Demands for energy storage are only going up, and lithium batteries is where it’s at, currently. We just need to find the paths of least environmental damage, because there won’t be any path that doesn’t harm the environment.