[en] In pressurized water reactors one tries to prevent the formation of steam in the reactor pressure vessel, which has adverse effects on heat removal in fault cases, by spraying with water. For this purpose a further coolant pipe is placed with its outlet at the highest point of the lid of the reactor pressure vessel, according to the invention. The coolant pipe is fed from the volume control system of the primary coolant circuit, for example, so that relatively cold water is available for condensing the steam. (orig.)