A high temperature gas cooled reactor steam generation system (1) includes a nuclear reactor (2) that has helium gas as a primary coolant and heats the primary coolant by heat generated by a nuclear reaction that decelerates neutrons by a graphite block, a steam generator (3) that has water as a secondary coolant and heats the secondary coolant by the primary coolant via the nuclear reactor (2) to generate steam, a steam turbine (4) that is operated by the steam from the steam generator (3), and a generator (5) that generates electricity according to an operation of the steam turbine (4). Moreover, the system (1) includes pressure adjustment means for setting a pressure of the secondary coolant in the steam generator (3) to be lower than a pressure of the primary coolant in the nuclear reactor (2).

In one implementation, a passive core decay heat transport system comprising of a device in the reactor core and an assembly of heat dissipating fins is disclosed. The device comprises at least one coolant channel 2 containing the fuel assembly 3; at least one collect joint 4 connecting the fuel in the assembly to shield plug 6; at least one liquid metal thermo-siphon 5 for transporting of decay heat from fuel; at least one other liquid metal thermo-siphon 7 for transport of heat from thermo-siphon 5; and at least an assembly of heat dissipating fins 10 for transport of heat from thermo-siphon 7 to ultimate sink. The thermal expansion of the liquid metal by melting establishes the conductive and convective heat transfer paths and transfers the heat from the fuel assembly 3 to the thermo-siphon 5, which transports the heat to other thermo-siphon 7 and then to the assembly of fin 10, which dissipates the heat by natural circulation of air to atmospheric air.

In one implementation, a passive core decay heat transport system comprising of a device in the reactor core and an assembly of heat dissipating fins is disclosed. The device comprises at least one coolant channel 2 containing the fuel assembly 3; at least one collect joint 4 connecting the fuel in the assembly to shield plug 6; at least one liquid metal thermo-siphon 5 for transporting of decay heat from fuel; at least one other liquid metal thermo-siphon 7 for transport of heat from thermo-siphon 5; and at least an assembly of heat dissipating fins 10 for transport of heat from thermo-siphon 7 to ultimate sink. The thermal expansion of the liquid metal by melting establishes the conductive and convective heat transfer paths and transfers the heat from the fuel assembly 3 to the thermo-siphon 5, which transports the heat to other thermo-siphon 7 and then to the assembly of fin 10, which dissipates the heat by natural circulation of air to atmospheric air.

A nuclear reactor can include a pressure vessel for containing a pressurized moderator at a first pressure. The nuclear reactor can also include a plurality of fuel channels for a coolant fluid at a second pressure. The plurality of fuel channels are fluidly connected at inlet ends thereof to a coolant supply conduit and are adapted to receive nuclear fuel bundles and to be mounted within the pressure vessel and surrounded by the moderator. The outlet ends of the fuel channels are fluidly connected to a coolant outlet conduit to enable the coolant fluid to circulate from the coolant supply conduit through the fuel channels to the coolant outlet conduit. The plurality of fuel channels maintain separation between the coolant fluid circulating within the fuel channels and the moderator.