Complex sentence: Nuclear reactors are used at nuclear power plants for electricity generation and in propulsion of ships.Infrared, that is to say heat, from nuclear fission is passed to a working fluid (water or gas), which runs through turbines.
Split into simpler sentences: Nuclear reactors are used at nuclear power plants for electricity generation and in propulsion of ships. Heat from nuclear fission is passed to a working fluid (water or gas), which runs through turbines.