The present invention relates to a
nuclear reactor, comprising a reactor vessel, a heat exchange device, a drive device, and a
water supply device. The reactor vessel contains liquid
coolant and an
air cavity. The heat exchange device is disposed within the reactor vessel, wherein the inner wall forms a first cavity for accommodating a core, and the outer and inner walls together define a second cavity. One end of the drive device is connected to the
air cavity, and the other end is disposed near the core. The
water supply device is in communication with the second cavity. When the
nuclear reactor is operating normally, the drive device causes the average density of the liquid
coolant above the top of the core to be lower than the average density of the lower cavity below the core, thereby generating a gravity difference that drives the liquid
coolant to circulate within the reactor vessel, transferring heat generated by the core. When the
nuclear reactor malfunctions, the circulating cold
source water in the
water supply device circulates in the second cavity, continuously exchanging heat with the core to remove
excess heat from the core. The present invention eliminates the need for a large main pump, reduces costs, and improves the safety and reliability of the nuclear reactor.