It is not a closed system, sure, but with current technology, we have at least decades, if not centuries of nuclear fuel reserves. If we count future tech that

It is not a closed system, sure, but with current technology, we have at least decades, if not centuries of nuclear fuel reserves. If we count future tech that we already have proofs-of-concept for, millennia. By the time, I hope we have something more exciting (fusion maybe). Nuclear waste is a non-problem, seriously. Yes, the material itself is pretty bad, but compared to the other pollutants, the quantities are tiny and easily manageable. What is a problem right are the waste products of combustion, CO2 in particular, but also things like coal ash that is radioactive and is not conveniently contained in barrels. Unlike with nuclear power where we have a couple hundred years to deal with potential problems coming from its non-renewable nature, carbon emissions are a problem we need to do something about right now.