Boiling water nuclear reactor. Cutaway computer illustration showing the internal structure of a boiling water reactor (BWR) - a form of light water nuclear reactor. In a BWR, the core (orange columns) is suspended in water (blue). The heat produced by the nuclear reactions boils the water into steam (white). This turns a turbine (not seen), which drives an electricity generator (not seen). The steam then passes through a condenser, before being passed back into the reactor chamber. The water acts as both the reactor coolant and the moderator. Control rods (red) can be raised or lowered to control the reaction. This is a cheap and simple reactor.