Combined cleanup and heat sink systems work with nuclear reactor coolant loops. Combined systems may join hotter and colder sections of the coolant loops in parallel with any steam generator or other extractor and provide optional heat removal between the same. Combined systems also remove impurities or debris from a fluid coolant without significant heat loss from the coolant. A cooler in the combined system may increase in capacity or be augmented in number to move between purifying cooling and major heat removal from the coolant, potentially as an emergency cooler. The cooler may be joined to the hotter and colder sections through valved flow paths depending on desired functionality. Sections of the coolant loops may be fully above the cooler, which may be above the reactor, to drive flow by gravity and enhance isolation of sections of the coolant loop.

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.

The steam generating unit of dual circuit reactor with blowdown and drain system is implemented in the close loop, without any conventional blowdown expansion tanks and is designed for maximum pressure of the steam generator (SG) working medium. The SG blowdown water is combined into a single line, cooled down in the regenerative heat exchanger, then in the blowdown aftercooler and drain cooling line and taken out of the tight shell. Out of the tight shell, the SG blowdown water is supplied for treatment to the SG blowdown water treatment system designed for maximum pressure of the steam generator (SG) working medium. After treatment, the water returns to the tight shell and, via the regenerative heat exchanger, to the feed pipelines of each SG. The invention provides increased SG blowdown that leads to the accelerated chemical condition normalization even with considerable deviations.

Combined cleanup and heat sink systems work with nuclear reactor coolant loops. Combined systems may join hotter and colder sections of the coolant loops in parallel with any steam generator or other extractor and provide optional heat removal between the same. Combined systems also remove impurities or debris from a fluid coolant without significant heat loss from the coolant. A cooler in the combined system may increase in capacity or be augmented in number to move between purifying cooling and major heat removal from the coolant, potentially as an emergency cooler. The cooler may be joined to the hotter and colder sections through valved flow paths depending on desired functionality. Sections of the coolant loops may be fully above the cooler, which may be above the reactor, to drive flow by gravity and enhance isolation of sections of the coolant loop.

A method is provided for evaluating simultaneously the effects of multiple, interdependent heat-exchanger degradation modes for a heat exchanger of a power plant in the context of a series of alternative heat-exchanger remediation strategies. The method includes calculating time-varying predicted future progressions of heat exchanger performance metrics for a plurality of alternative heat-exchanger remediation strategies, and calculating time-varying predicted future progressions of financial metrics describing the accumulated financial benefit of each of the strategies. The calculations may be provided in probabilistic terms. A strategy may then be chosen based, at least in part, on the calculated results.

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.

An in-vessel cooling and power generation system according to the present disclosure may include a small scale reactor vessel, a heat exchange section provided inside the reactor vessel, and formed to supply supercritical fluid to receive heat from a reactor coolant system in the reactor vessel, an electric power production section comprising a supercritical turbine formed to produce electric energy using the energy of the supercritical fluid whose temperature has increased while receiving heat from the reactor coolant system, a cooling section configured to exchange heat with the supercritical fluid discharged after driving the supercritical turbine to shrink a volume of the supercritical fluid, wherein the supercritical fluid that has received heat from the reactor coolant system in the heat exchange section is formed to circulate through the electric power production section, and the cooling section.

According to the disclosure, a position of a main control valve and a position of an auxiliary control valve are adjusted. In particular, a position of the auxiliary control valve is adjusted by determining whether a change in the position of the main control valve is in a preset deadband range, thereby preventing a periodic water level fluctuation of a steam generator.

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 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.