Abstract: The system removes heat from a vessel containing the source of heat, utilizing heat energy from water circulating through the vessel. The circulating water passes through a subcooler and into a convergent-divergent nozzle of a flash jet pump. Cooled water is drawn into the flash jet pump by the high-velocity flow generated, mixes with the water flashed into steam and condenses it. The mixture flows to the inlet connection of the pressure vessel. A second flash jet pump is utilized to initially fill the vessel with coolant water. Steam in the vessel is condensed in a shock condenser.