Solar uses rare earth mineral resources for pannel production (as do the batteries of your cell phone and every hybrid car) those are running out at an alarming rate. Steam or even wood-gas dumps lots of carbon, if we all changed to that we'd blot out the sun and enjoy daily acid rain. Nuclear is about as clean as it gets especially with Gates's new process that runs off other reactor's spent fuel rods (he's building 3 in china)
Rare earth minerals aren't actually "rare" as in there's not many of them (
https://cleantechnica.com/2018/02/01/renewable-energy-made-available-resources/), it's an archaic term that dates back centuries. The resources used in a solar panel and batteries are also recyclable. Nuclear, on the other hand, relies on a non-recyclable, actually rare resource. And requires a centralized power grid that gives control over your power to a large monopolistic corporation that has no responsibility to treat you like a customer and will inevitably fail in the smallest emergency. Plus, you're ignoring the wide variety of alternative energy sources like wind, geothermal, tidal, hydro, and the fact that solar panel technology is rapidly changing and improving, with development on panels that don't require rare earths.
The ideal, safe nuclear may be clean, but unfortunately we aren't ever going to get that. Managers cut corners, people make mistakes, unpredictable accidents happen, and when it breaks we all have to pay the cost. We can't just assume that the people designing, operating, and maintaining all these nuclear plants won't make any mistakes, and that there won't ever be any successful deliberate sabotage (like the way we used a computer virus to sabotage Iran's development of a nuclear plant), and that every possibility of failure is covered and protected against. Not when the stakes are so high.