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 power system includes a reactor vessel that includes a reactor core mounted, the reactor core including 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 below the reactor core, through the reactor core, within the riser, and through an annulus between the riser and the reactor vessel back to the bottom portion of the volume; 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 system fluidly or thermally coupled to the primary coolant flow path; 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 during the normal operation.

A self-excited vibration evaluation method for evaluating self-excited vibration of a tube bundle arranged in a fluid so as to be supported by a support member includes: for each of at least one eigenmode of the tube bundle, a time history response analysis step of performing time history response analysis of simulating a change in vibration amplitude of the tube bundle, while changing a negative damping ratio corresponding to an excitation force of the fluid; calculating a critical flow velocity of the fluid on the basis of a minimum negative damping ratio at which the change of the vibration amplitude of the tube bundle diverges in the time history response analysis; inputting an expected flow velocity of the fluid; and evaluating the self-excited vibration of the tube bundle for each eigenmode by comparing the expected flow velocity of the fluid with the critical flow velocity.

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 there actor 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.

A nuclear power plant, having a reactor pressure vessel; a steam generator arranged to generate steam utilising thermal energy generated within the reactor pressure vessel; and a fluid circuit for transferring thermal energy from the reactor pressure vessel to the steam generator. The plant also has a coolant reservoir for storing coolant for supply to the steam generator under gravity in emergency conditions. The steam generator has a steam drying zone comprising one or more steam separators configured to dry steam; and the steam generator and coolant reservoir are configured such that when coolant is supplied from the coolant reservoir to the steam generator in emergency conditions the coolant stays below a threshold level defined by the steam drying zone.

A nuclear reactor cooled by liquid metal or by molten salts, provided with a heat exchanger, having inlet of the primary fluid in the lower part and circumferential outlet window in the vicinity of the free surface of the primary fluid in the cold collector. The outlet window is located in an intermediate position with respect to the tube bundle partially raised with respect to the free surface in the cold collector and supplied with primary fluid throughout its height by means of an ancillary device for creating an underpressure in the cover gas of the exchanger with respect to the cover gas in the vessel. The raising of the exchanger and the positioning of the outlet window in the vicinity of the free surface of the primary coolant help to minimize the displacement of primary fluid in the event of accidental release of secondary fluid inside the heat exchanger.

Provided are a method and system for improving control of a steam generator level for preventing oscillation of the steam generator level in a nuclear power plant. In order to prevent oscillation of a steam generator level and resultant shutdown of a nuclear reactor, which may be caused when a high-level priority control function is frequently and repeatedly turned on/off as the steam generator level is excessively increased, by improving a feedwater control system in the nuclear power plant, a proportional integral control value may be controlled to be reduced, and thus, output while a certain condition is met after a high-level priority mode is deactivated or a signal instructing to enter the high-level priority control mode may be controlled not to be output.

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 nuclear power system further includes a chemical injection system configured to inject a chemical into the reactor vessel and remove the chemical from the reactor vessel, and a control system communicably coupled to the chemical injection system and configured to control a power output of the nuclear fission reaction. For example, the control system can determine that the power output is greater than an upper value of a range or less than a lower value of the range and, based on the determination, adjust an amount of the chemical injected into or removed from the reactor vessel by the chemical injection system to adjust the power output.

The present invention relates to an apparatus for efficiently and economically generating a cooling medium by using high-temperature and high-pressure steam generated in a nuclear power plant, and cooling method therefor. According to one embodiment of the present invention, the cooling medium generating apparatus provided in a containment vessel of a nuclear power generation facility so as to generate the cooling medium can comprise: a nuclear reactor for heating a coolant by using heat included in the heated coolant; a cooling module for generating the cooling medium by using the steam generated in the steam generator; and a cooling medium supplying pipe of which the end portion is connected to the outside of the containment vessel so as to supply the cooling medium, having been generated in the cooling module, to the outside of the containment vessel.

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.