Hold a bunch of special rocks close together. They get hot and make water hot. And turns into hot, wet air, which turns a big fan. Hook a magnet to that fan, and spin it in some hoops and you get electricity. Oh, and always, always, always keep the rocks from getting too hot.
Compare that to solar cells, which are semiconductors doped with cleverly designed impurities, and layered to exploit quantum effects to deliver electrical power simply by pointing it at the sun. You can make it more useful by hooking it to a rechargeable battery, which also exploits clever quantum chemical effects to store that electricity. And the combo of these two wonderful quantum-technological devices is cheaper than the reactor.
Both technologies require understanding of modern physics, but it's pretty telling that you can do enough math to make a fission reactor with a hand calculator, and not a high-powered computer.
Solar cells in space are a great idea. Much more efficient than nuclear power when you're closer than the orbit of Venus. A lot less so when you're at the bottom of an atmosphere with dust and clouds.
Because coal and nuclear are in so many cave paintins
It takes a long time and a lot of money to start earning on a nuclear plant. Given the risks involved it's not that easy to build one.
https://www.youtube.com/watch?v=cbeJIwF1pVY
I don't think firing nuclear waste into space would be wise either. The risk of that blowing up on launch is high and the fall out from that would be a disaster.
All of the used fuel ever produced by the commercial nuclear industry since the late 1950s would cover a football field to a depth of less than 10 yards.