A nuclear power system includes a reactor vessel that includes a reactor core mounted within a volume of the reactor vessel. The reactor core includes one or more nuclear fuel assemblies configured to generate a nuclear fission reaction. The nuclear power system further includes a containment vessel sized to enclose the reactor vessel such that an open volume is defined between the containment vessel and the reactor vessel. A boron injection system is positioned in the open volume of the containment vessel and includes an amount of boron sufficient to stop the nuclear fission reaction or maintain the nuclear fission reaction at a sub-critical state. The boron injection system is positioned to deliver the amount of boron into the open volume.

A reactor containment vessel vent system continuously releases steam generated in a reactor containment vessel to the atmosphere even when a power supply is lost. In the reactor containment vessel vent system, the noble gas filter that allows steam to pass through but does not allow radioactive noble gases to pass through among vent gas discharged from the reactor containment vessel is provided at a most downstream portion of the vent line. An immediate upstream portion of the noble gas filter and the reactor containment vessel are connected to each other by the return pipe via the intermediate vessel. When the radioactive noble gases having pressure equal to or higher than predetermined pressure stay in the immediate upstream portion of the noble gas filter, the staying radioactive noble gases flows into the intermediate vessel by the relief valve. Thus, steam permeability is maintained and the system continuously releases the steam.

A nuclear power system includes a reactor vessel that includes a reactor core that includes nuclear fuel assemblies configured to generate a nuclear fission reaction; a riser positioned above the reactor core; a primary coolant flow path that extends from a bottom portion of the volume through the reactor core and through an annulus between the riser and the reactor vessel; a primary coolant that circulates through the primary coolant flow path to receive heat from the nuclear fission reaction and release the heat to generate electric power in a power generation system; and a control rod assembly system positioned in the reactor vessel and configured to position control rods in only two discrete positions.

A nuclear containment atmospheric filter including dedicated piping, valves, a control system and a chemical injection system to facilitate the use of a commercial nuclear power plant's Spent Fuel Storage Pool and Spent Fuel Storage Pool Cooling System to filter and cool contaminated air and steam vapor released from within a Reactor Containment Vessel/Building preventing vessel overpressure and radioactive release.

Damper systems selectively reduce coolant fluid flow in nuclear reactor passive cooling systems, including related RVACS. Systems include a damper that blocks the flow in a coolant conduit and is moveable to open, closed, and intermediate positions. The damper blocks the coolant flow when closed to prevent heat loss, vibration, and development of large temperature gradients, and the damper passively opens, to allow full coolant flow, at failure and in transient scenarios. The damper may be moveable by an attachment extending into the coolant channel that holds the damper in a closed position. When a transient occurs, the resulting loss of power and/or overheat causes the attachment to stop holding the damper, which may be driven by gravity, pressure, a spring, or other passive structure into the open position for full coolant flow. A power source and temperature-dependent switch may detect and stop holding the damper closed in such scenarios.

A nuclear power system includes a reactor vessel that includes a reactor core mounted therein. The reactor core includes nuclear fuel assemblies configured to generate a nuclear fission reaction. The reaction vessel does not include any control rod assemblies therein. The nuclear power system further includes a riser positioned above the reactor core, a primary coolant flow path, a primary coolant that circulates through the primary coolant flow path to receive heat from the nuclear fission reaction and release the received heat to generate electric power in a power generation, and a control system communicably coupled to the power generation system and configured to control a power output of the nuclear fission reaction independent of any control rod assemblies.

The invention provides a reactor containment vessel vent system capable of continuously releasing steam generated in a reactor containment vessel to the atmosphere even when a power supply is lost. In the reactor containment vessel vent system (15), the noble gas filter (23) that allows steam to pass through but does not allow radioactive noble gases to pass through among vent gas discharged from the reactor containment vessel (1) is provided at a most downstream portion of the vent line. An immediate upstream portion of the noble gas filter (23) and the reactor containment vessel (1) are connected to each other by the return pipe (24a, 24b) via the intermediate vessel (100). Further, when the radioactive noble gases having pressure equal to or higher than predetermined pressure stays in the immediate upstream portion of the noble gas filter (23), the staying radioactive noble gases flows into the intermediate vessel (100) by the relief valve (25). Thus, the noble gas filter (23) does not lose steam permeability, and the reactor containment vessel vent system (15) can continuously release the steam to the atmosphere.

A nuclear power reactor which includes passive cooling and radiation scrubbing. The reactor includes a first containment member which is buried in the ground. A second containment member is positioned in the first containment member and has a reactor vessel therein. The discharge side of the reactor vessel is connected to a heat exchanger which drives a turbine which drives a device such as a generator. A source of water is provided which gravity feeds cooling water to the interior of the first containment member in the event of reactor overheating or over-pressurization. A radiation scrubber is provided for scrubbing radiation which may be in the first containment member or the second containment member.

A nuclear power system includes a reactor vessel that includes a reactor core that includes nuclear fuel assemblies configured to generate a nuclear fission reaction. A representative nuclear power system further includes a riser positioned above the reactor core and a primary coolant flow path that extends from a bottom portion of the reactor vessel, through the reactor core, and through an annulus between the riser and the reactor vessel. A primary coolant circulates through the primary coolant flow path to receive heat from the nuclear fission reaction and release the heat to a power generation system configured to generate electric power. The nuclear power system further includes a control rod assembly system positioned in the reactor vessel and configured to position control rods in only two discrete positions.

Damper systems selectively reduce coolant fluid flow in nuclear reactor passive cooling systems, including related RVACS. Systems include a damper that blocks the flow in a coolant conduit and is moveable to open, closed, and intermediate positions. The damper blocks the coolant flow when closed to prevent heat loss, vibration, and development of large temperature gradients, and the damper passively opens, to allow full coolant flow, at failure and in transient scenarios. The damper may be moveable by an attachment extending into the coolant channel that holds the damper in a closed position. When a transient occurs, the resulting loss of power and/or overheat causes the attachment to stop holding the damper, which may be driven by gravity, pressure, a spring, or other passive structure into the open position for full coolant flow. A power source and temperature-dependent switch may detect and stop holding the damper closed in such scenarios.