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.

A low pressure water reactor (LPWR) and a method for controlling a LPWR; the LPWR comprises a reactor vessel with an internal cavity comprising a primary coolant, a riser tube, and a core located below ground level with 6-15 bars atmosphere pressure; a steam drum connected to the riser tube at ground level at a pressure of 1-10 bars absolute; a water storage tank to store borated water; a passive injection system injecting the borated water from the water storage tank into the vessel; and low pressure steam turbines generating power at 1-10 bars atmosphere. The vessel heats water up to temperature and the riser tube converts the heated water to steam, delivered to the turbine(s). The conversion creates a difference in a primary coolant density that initiates a density-driven natural circulation of the primary coolant in the riser tube, downcomer, steam drum and core.

A low pressure water reactor (LPWR) and a method for controlling a LPWR; the LPWR comprises a reactor vessel with an internal cavity comprising a primary coolant, a riser tube, and a core located below ground level with 6-15 bars atmosphere pressure; a steam drum connected to the riser tube at ground level at a pressure of 1-10 bars absolute; a water storage tank to store borated water; a passive injection system injecting the borated water from the water storage tank into the vessel; and low pressure steam turbines generating power at 1-10 bars atmosphere. The vessel heats water up to temperature and the riser tube converts the heated water to steam, delivered to the turbine(s). The conversion creates a difference in a primary coolant density that initiates a density-driven natural circulation of the primary coolant in the riser tube, downcomer, steam drum and core.

A nuclear reactor system includes a first drillhole extending from a terranean surface through one or more subterranean formations; a reactor core positioned in the first drillhole, and including at least one nuclear fuel element; a second drillhole extending from the terranean surface through the one or more subterranean formations and separated from the first drillhole by a portion of a rock formation; a heat exchanger positioned in the second drillhole in thermal communication with the reactor core through the portion of the rock formation; and a coolant system thermally coupled to the heat exchanger and configured to transport a fluid coolant between the heat exchanger and the terranean surface.

A nuclear reactor system includes a first drillhole extending from a terranean surface through one or more subterranean formations; a reactor core positioned in the first drillhole, and including at least one nuclear fuel element; a second drillhole extending from the terranean surface through the one or more subterranean formations and separated from the first drillhole by a portion of a rock formation; a heat exchanger positioned in the second drillhole in thermal communication with the reactor core through the portion of the rock formation; and a coolant system thermally coupled to the heat exchanger and configured to transport a fluid coolant between the heat exchanger and the terranean surface.

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 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.

The present invention relates to a nuclear reactor, more precisely a passive safety device applicable to a thermal neutron reactor and a nuclear fuel assembly equipped with the same. The nuclear fuel assembly for a thermal neutron reactor of the present invention includes multiple fuel rods; multiple guide thimbles arranged between the fuel rods; and a passive safety device including neutron absorber parts which are inserted in one or more guide thimbles.

The invention relates to nuclear reactor protection systems and can be used when building nuclear reactors, in particular, the fast neutron reactors. The Technical result of the invention consists in the expansion of 5 functional capabilities of the negative reactivity passive insertion device by securing its reliable actuation in various emergency conditions. The device has two vessels located in a common enclosure one under another with a ring-shape hollow space between the vessels and the enclosure to let the heat carrier flow. Fuel elements are located in the ring-shape hollow space, as well as the tooling for the heat carrier flow formation to cool the fuel elements and heat the upper vessel. The upper vessel is located above the reactor core and is divided with an internal partition wall to the central cylindrical and ring-shape hollow spaces. The partition wall has low thermal conductivity in the transverse direction. In the central hollow space of the upper vessel the cadmium isotope is mainly located, while in its ring-shape spacemercury. Lower vessel is mainly located in the active core of the reactor and filled with inert gas. The vessels and are connected with a pipe with a partition, made in the form of buckling rapture disc.

The invention relates to nuclear reactor protection systems and can be used when building nuclear reactors, in particular, the fast neutron reactors. The Technical result of the invention consists in the expansion of 5 functional capabilities of the negative reactivity passive insertion device by securing its reliable actuation in various emergency conditions. The device has two vessels located in a common enclosure one under another with a ring-shape hollow space between the vessels and the enclosure to let the heat carrier flow. Fuel elements are located in the ring-shape hollow space, as well as the tooling for the heat carrier flow formation to cool the fuel elements and heat the upper vessel. The upper vessel is located above the reactor core and is divided with an internal partition wall to the central cylindrical and ring-shape hollow spaces. The partition wall has low thermal conductivity in the transverse direction. In the central hollow space of the upper vessel the cadmium isotope is mainly located, while in its ring-shape spacemercury. Lower vessel is mainly located in the active core of the reactor and filled with inert gas. The vessels and are connected with a pipe with a partition, made in the form of buckling rapture disc.