system for the removal of residual heat from a nuclear reactor cooled by liquid metal or molten salt

摘要

A system for evacuating the residual heat from a nuclear reactor cooled with liquid metal or molten salts has two types of heat exchangers immersed in the primary fluid of the reactor: heat exchangers with higher power density, which use boiling water as secondary cooling fluid and are particularly suitable for evacuating the residual heat in the first days after turning-off of the reactor; and heat exchangers operating with atmospheric air or with water and suitable for evacuating the residual heat for indefinite periods of time. Both types of heat exchangers present a bundle of heat-exchange elements, shaped in such a way that the secondary fluid circulating in each element is separated from the primary fluid of the reactor by a double wall of the element, which delimits a gap introduced in which is a pressurized inert gas having the function of continuous monitoring of the integrity of the heat exchanger and of thermal resistance calibrated for preventing solidification of the primary fluid of the reactor in the heat exchanger.