There are some new reactor designs out there that run off old nukes and some that run off nuclear waste. They are also working on designs that don't melt down. The Voyager space probes, that have been operating since the 70s, are nuclear powered. NASA also developed nuclear rocket engines back in the day.

https://www.technologyreview.com/2024/01/18/1086753/advanced-nuclear-power/

Every form of energy is going to have some negatives, solar fields destroy biodiversity and leach heavy metals into the soil, turning forests into deserts. Coal kills the miners by 50. Windmills don't work very well, require a lot of oil and massive amounts of energy to produce, so they seldom produce any net energy and they kill a whole lot of birds.