Well … unless you use your uranium reactor to create plutonium… But, you’re right – even then, it would eventually run out. So fission power isn’t renewable.
Fusion power, though… If you can make a viable fusion reactor ecosystem that can use regular ordinary hydrogen as its input fuel, then that’s at least psuedo-renewable. Yeah, eventually you’ll have converted so much hydrogen into helium that hydrogen might start running low. But I’m guessing you could power 100 earths for 10 billion years before you used even half the hydrogen available.
Well … unless you use your uranium reactor to create plutonium… But, you’re right – even then, it would eventually run out. So fission power isn’t renewable.
Fusion power, though… If you can make a viable fusion reactor ecosystem that can use regular ordinary hydrogen as its input fuel, then that’s at least psuedo-renewable. Yeah, eventually you’ll have converted so much hydrogen into helium that hydrogen might start running low. But I’m guessing you could power 100 earths for 10 billion years before you used even half the hydrogen available.