A boiling water reactor system includes a reactor vessel including a reactor core. A steam line is in communication with the reactor core and a turbine that is connected to an electrical generator. A dry standby liquid control system includes a standby vessel containing dry powder containing boron and including a high pressure water supply in communication with the standby vessel via a first closed valve, wherein the standby vessel is in communication with the reactor vessel via a second closed valve.

A boiling water reactor system includes a reactor vessel including a reactor core. A steam line is in communication with the reactor core and a turbine that is connected to an electrical generator. A dry standby liquid control system includes a standby vessel containing dry powder containing boron and including a high pressure water supply in communication with the standby vessel via a first closed valve, wherein the standby vessel is in communication with the reactor vessel via a second closed valve.

A flow restrictor nozzle for a pressurized vessel of a nuclear reactor may comprise a nozzle body including an inlet face and an outlet face. The nozzle body may define a plurality of internal flow paths extending from the inlet face to the outlet face. Each of the plurality of internal flow paths may include a convergent section, a throat section, and a divergent section.

A flow restrictor nozzle for a pressurized vessel of a nuclear reactor may comprise a nozzle body including an inlet face and an outlet face. The nozzle body may define a plurality of internal flow paths extending from the inlet face to the outlet face. Each of the plurality of internal flow paths may include a convergent section, a throat section, and a divergent section.

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.

According to at least some example embodiments, a dome collector separation stage includes an inner side wall that defines an inner channel; and an outer side wall that, together with the inner side wall, defines an outer channel, the inner channel being configured to receive a two-phase flow stream (FS) of water and steam, and pass the two-phase FS to the outer channel via inlets included in the inner side wall, the outer channel being configured to separate at least some water from the two-phase FS, and pass moisture-reduced steam out of the steam separator stage via outlets included in the outer side wall.

According to at least some example embodiments, a dome collector separation stage includes an inner side wall that defines an inner channel; and an outer side wall that, together with the inner side wall, defines an outer channel, the inner channel being configured to receive a two-phase flow stream (FS) of water and steam, and pass the two-phase FS to the outer channel via inlets included in the inner side wall, the outer channel being configured to separate at least some water from the two-phase FS, and pass moisture-reduced steam out of the steam separator stage via outlets included in the outer side wall.

A nuclear reactor cooling system comprises a containment area, an In-Containment Refueling Water Storage Tank (IRWST), and a discharge pipe. The containment area is formed to enclose a reactor coolant system. The IRWST is disposed outside the containment area. The discharge pipe discharges steam from the containment area to refueling water in the IRWST when an accident occurs. A steam intake pipe has one end in fluid connection with an upper space of the IRWST, and another end in fluid connection with a radioactive substance reduction tank which stores cooling water. The steam intake pipe allows steam to flow from the upper space of the IRWST into the cooling water in the reduction tank.

An external reactor vessel cooling and electric power generation system according to the present invention includes an external reactor vessel cooling section formed to enclose at least part of a reactor vessel with small-scale facilities so as to cool heat discharged from the reactor vessel, a power production section including a small turbine and a small generator to generate electric energy using a fluid that receives heat from the external reactor vessel cooling section, a condensation heat exchange section 140 to perform a heat exchange of the fluid discharged after operating the small turbine, and condense the fluid to generate condensed water, and a condensed water storage section to collect therein the condensed water generated in the condensation heat exchange section, wherein the fluid is phase-changed into gas by the heat received from the reactor vessel. The external reactor vessel cooling and electric power generation system according to the present invention can continuously operate even during an accident as well as during a normal operation to cool the reactor vessel and produce emergency power, thereby enhancing system reliability. The external reactor vessel cooling and electric power generation system according to the present invention can easily apply safety class or seismic design using small-scale facilities, and its reliability can be improved owing to applying the safety class or seismic design.