That's steam coming out of a nuclear powerplant, if it's smoke you should worry.
Fission works on the premise that radioactive rods heat water, create vast ammounts of steam, turn turbines, which turn magnets inside dense wire coils which generates an electrical charge.
Fusion works on the premise that when two atoms combine (this is true for anything larger than iron 56), they tend to combine into a single nucleus which is smaller in mass than the combination of the original pair, the excess mass is expelled as heat energy, which is then used to heat water, turn turbines..... you get the idea.
The thing about fusion is that the isotope used in most designs is a hydrogen isotope and they use lithium to pickup neutrons that fly off randomly....
Enough of the chemistry lesson, no released steam, go read a degree level chemistry book