A thermal control system for a reactor pressure vessel comprises a plate having a substantially circular shape that is attached to a wall of the reactor pressure vessel. The plate divides the reactor pressure vessel into an upper reactor pressure vessel region and a lower reactor pressure vessel region. Additionally, the plate is configured to provide a thermal barrier between a pressurized volume located within the upper reactor pressure vessel region and primary coolant located within the lower reactor pressure vessel region. One or more plenums provide a passageway for a plurality of heat transfer tubes to pass through the wall of the reactor pressure vessel. The plurality of heat transfer tubes are connected to the plate.

A thermal control system for a reactor pressure vessel comprises a plate having a substantially circular shape that is attached to a wall of the reactor pressure vessel. The plate divides the reactor pressure vessel into an upper reactor pressure vessel region and a lower reactor pressure vessel region. Additionally, the plate is configured to provide a thermal barrier between a pressurized volume located within the upper reactor pressure vessel region and primary coolant located within the lower reactor pressure vessel region. One or more plenums provide a passageway for a plurality of heat transfer tubes to pass through the wall of the reactor pressure vessel. The plurality of heat transfer tubes are connected to the plate.

A thermal control system for a reactor pressure vessel comprises a plate having a substantially circular shape that is attached to a wall of the reactor pressure vessel. The plate divides the reactor pressure vessel into an upper reactor pressure vessel region and a lower reactor pressure vessel region. Additionally, the plate is configured to provide a thermal barrier between a pressurized volume located within the upper reactor pressure vessel region and primary coolant located within the lower reactor pressure vessel region. One or more plenums provide a passageway for a plurality of heat transfer tubes to pass through the wall of the reactor pressure vessel. The plurality of heat transfer tubes are connected to the plate.

A thermal control system for a reactor pressure vessel comprises a plate having a substantially circular shape that is attached to a wall of the reactor pressure vessel. The plate divides the reactor pressure vessel into an upper reactor pressure vessel region and a lower reactor pressure vessel region. Additionally, the plate is configured to provide a thermal barrier between a pressurized volume located within the upper reactor pressure vessel region and primary coolant located within the lower reactor pressure vessel region. One or more plenums provide a passageway for a plurality of heat transfer tubes to pass through the wall of the reactor pressure vessel. The plurality of heat transfer tubes are connected to the plate.

In one embodiment, the steam separator includes a standpipe configured to receive a gas-liquid two-phase flow stream, and a first swirler configured to receive the gas-liquid two-phase flow stream from the standpipe. The first swirler is configured to separate the gas-liquid two-phase flow stream. The first swirler includes a direct flow portion and an indirect flow portion. The direct flow portion has a direct flow channel for permitting direct flow of the gas-liquid two-phase flow stream through the first swirler, and the indirect flow portion has at least one indirect flow channel defined by at least one vane in the first swirler for providing an indirect flow of the gas-liquid two-phase flow stream through the first swirler.

In one embodiment, the steam separator includes a standpipe configured to receive a gas-liquid two-phase flow stream, and a first swirler configured to receive the gas-liquid two-phase flow stream from the standpipe. The first swirler is configured to separate the gas-liquid two-phase flow stream. The first swirler includes a direct flow portion and an indirect flow portion. The direct flow portion has a direct flow channel for permitting direct flow of the gas-liquid two-phase flow stream through the first swirler, and the indirect flow portion has at least one indirect flow channel defined by at least one vane in the first swirler for providing an indirect flow of the gas-liquid two-phase flow stream through the first swirler.

In an externally integrated steam generator type small modular reactor, a steam generator is arranged along the circumference of a reactor vessel cylindrical shell, and a steam drum is arranged along the circumference of the steam generator. The small modular reactor includes: a nuclear reactor including a hemispherical upper head, the reactor vessel cylindrical shell coupled to the upper head and extending downward from the upper head in a cylindrical shape, and a hemispherical lower head provided on a lower portion of the reactor vessel cylindrical shell, wherein a core is placed in the nuclear reactor; the steam generator surrounding all around the reactor vessel cylindrical shell and including a first penetration hole communicating with an inside of the nuclear reactor; and the steam drum surrounding the circumference of the steam generator and including a second penetration hole communicating with an inside of the steam generator.

A high-temperature gas-cooled reactor (HTGR) core is disclosed which includes a plurality of nuclear fuel kernels encapsulated by i) solid structures; and ii) porous structures, wherein the solid structures and the porous structures form a heterogeneous tileable repeating assembly including a channel for moving heat out of the HTGR core, wherein a ratio of in-channel porosity to in-channel tortuosity of the assembly is between about 0.2 to about 0.5, wherein the in-channel tortuosity is between about 1.0 and 1.6, and wherein total solid fraction of the assembly is between about 0.6 to about 0.85.

A high-temperature gas-cooled reactor (HTGR) core is disclosed which includes a plurality of nuclear fuel kernels encapsulated by i) solid structures; and ii) porous structures, wherein the solid structures and the porous structures form a heterogeneous tileable repeating assembly including a channel for moving heat out of the HTGR core, wherein a ratio of in-channel porosity to in-channel tortuosity of the assembly is between about 0.2 to about 0.5, wherein the in-channel tortuosity is between about 1.0 and 1.6, and wherein total solid fraction of the assembly is between about 0.6 to about 0.85.

A chimney structure according to a non-limiting example embodiment may include a guide structure defining an opening, and a plurality of chimney partitions including 1 to N chimney partitions concentrically arranged and spaced apart from each other on the guide structure. The 1 to N chimney partitions may each define a curved opening over the opening the guide structure. N may be an integer greater than 1.