This is all from a stuff I learned mostly at Sheffield University's department of Engineering Materials. Or stuff I read in New Scientist magazine over the years.
Where ever nature is doing molecular nuclear fusion from water, we see the creation of gamma wave radiation, helium, ozone(O3) and heat. They serve as oxygen radical bonds with the oxygen molecule(O2) in the air.
We cannot detect the helium easily. A Geiger counter will detect the γ waves, and own noses will detect the ozone! When we smell ozone with no electric fields, nature is doing molecular nuclear fusion.
If we do have electric fields then man's engines are doing molecular nuclear fusion. More so if we have a lot the water molecules in the air.
Nature does it at waterfalls, with fields of green crops, in animal blood systems and or breaking waves. So this means your heart and arteries do MNF as you heart beats.
Man's steam cycle does so much of it. It turns water into heat and power with no carbon dioxide or toxic fission waste. It is the way life on earth powers itself. Simples. It requires turbulence, temperatures of above 3 C, and pressures over two bars.