Nuclear fission not so much, but it's definitely debatable which has more fundamental flaws between fission and wind/hydro/solar. All renewable energy sources ultimately depend on natural processes which are not reliable or permanent. And they also tend to disrupt the environment to some extent.

Nuclear fission has no such limitations, but instead trades long term risk for short term stability. Basically renewable sources are and always will be somewhat unreliable, and Nuclear fission is the least bad reliable energy source to pair with the renewables. So in the medium term, fission makes a lot more sense than fossil fuels, and in the long term we should be looking to fusion.