They already use nuclear power in loads of applications. The mars rover, perseverance satellites and even satellites in LEO. They can provide power during lengthy lunar nights and the heat they produce as a byproduct would be useful for keeping people warm. This isn’t even even mentioning advancements in nuclear reactor designs that make meltdowns conditions considerably less likely. Your right that solar cells are a great way to produce power in LEO but on the moon there are more variables that make it viable for a nuclear reactor to be a rational power source.