thorium? maybe. but all of the reactors currently dotting the globe, and any of those which may be built in the near future, all use uranium. I'd hate for us to make the mistake of basing decisions about whether or not to retire existing aging uranium reactors on the promises of theoretical thorium models. We certainly shouldn't keep building dangerous uranium reactors simply because, one day, hopefully, there might be thorium models that might be safer. Like I said : this industry's been promising more than they can deliver since Go.
waste: out of sight / out of mind? not good enough: this material should remain prominent in the eyes and minds of the technological wizards who created it.
Solar: these sound like valid concerns, and I don't know enough to answer them, but I'm pretty sure that there's a lot more to build before we hit those constraints.