Since we are talking about nuclear fission and fusion, could I add a brief description of both, just to add more content to the subject?
Please note that the informations below may be completely inaccurate, I'm just telling what I can remember right now)
Nuclear fission is performed by breaking atoms into smaller ones, releasing a great amount of energy in this process. The best elements to be used in nuclerar fission are instable isotopes of heavy atoms (uranium and plutonium, mostly). Unfortunately, the wastes of those atoms are very radioactive, and can cause many diseases to living beings. Those elements would decay to a non-radioactive atoms after thousands of years, and that's the main issue when we talk about where we should store them after their use in nuclear plants.
Nuclear fusion is the reverse process. It is known to happen inside our sun, in the other stars, and in Hidrogen BOmbs.It performs the junction of lighter atoms into heavy ones, releasing a huge amount of energy. The best element to be used in fusion is Hidrogen and its isotopes, and when the fusion is performed, the resulting elements are almost 100% Helium. Both elementts are not radiactive and therefore can't make harm to living beings.
We can see that nuclear fusion is radioactive-free, and is far more productive than nuclear fission. Unfortunatley, nuclear fusion is a very damn dificult process to handle in a controled experiment, such as a nuclear power plant. Plus, nuclear fusion needs a great amount of energy to happen, because the Hidrogen only "melts" into Helium at around 10 million Kelvin. that unbelievable heat can only be achieved inside the core of stars and nuclear fission bombs, that's why the trigger of a nuclear fusion bomb is, in fact, a nuclear fission bomb.
Conclusion [B](again, it may be totatlly inaccurate)[B]: Although Nuclear fusion would be much more economically viable to produce eletric energy in power plants, it wouldn't be a "clean" procees, since nuclear fission is still needed to produce nuclear fusion.
Because of this, I'm against nuclear power plants on Earth, there are other alternative energy source that are safer. When humans settle colonies on Moon, though, I think it could be a great source of energy over there.