A portable apparatus for borating a continuous flow of water includes metering assemblies provided with corresponding grinders and feeders; a feeder for supplying water to the circuit; a meter and/or flow regulator for adapting the concentration of the products supplied to the water; a pumping arrangement for conveying the mixture to a mixing reactor; a reactor with a mechanical mixer; a recirculation line of the mixer; and a supply pumping arrangement, preferably forming two units in independent cages or containers, including a crane arrangement for supplying the boration products in big bags.

A portable apparatus for borating a continuous flow of water includes metering assemblies provided with corresponding grinders and feeders; a feeder for supplying water to the circuit; a meter and/or flow regulator for adapting the concentration of the products supplied to the water; a pumping arrangement for conveying the mixture to a mixing reactor; a reactor with a mechanical mixer; a recirculation line of the mixer; and a supply pumping arrangement, preferably forming two units in independent cages or containers, including a crane arrangement for supplying the boration products in big bags.

A nuclear reactor provided with a core including a new fuel part which contains uranium and a burning part in which fuel burns, wherein the burning part moves in a direction toward the new fuel part from the beginning to end of the operation cycle. The nuclear reactor is provided with a reactivity applying mechanism to apply the reactivity which can change the power of the core when the temperature of the coolant which flows through the inside of the core changes and performs control to change the temperature of the coolant which flows through the inside of the core in accordance with the change of power which is demanded for the core. The reactivity applying mechanism includes a gap adjusting plate which supports fuel members. This plate is configured to expand when the core coolant temperature rises. The expansion increases distance between the fuel members.

A nuclear reactor provided with a core including a new fuel part which contains uranium and a burning part in which fuel burns, wherein the burning part moves in a direction toward the new fuel part from the beginning to end of the operation cycle. The nuclear reactor is provided with a reactivity applying mechanism to apply the reactivity which can change the power of the core when the temperature of the coolant which flows through the inside of the core changes and performs control to change the temperature of the coolant which flows through the inside of the core in accordance with the change of power which is demanded for the core. The reactivity applying mechanism includes a gap adjusting plate which supports fuel members. This plate is configured to expand when the core coolant temperature rises. The expansion increases distance between the fuel members.

A method for controlling reactivity in a nuclear reactor is provided. The method comprises circulating coolant through the nuclear reactor. A composition of the coolant comprises water and gadolinium. The gadolinium is present in the coolant at a concentration suitable for controlling a neutronic reactivity of the nuclear reactor. A method for adjusting reactivity in a nuclear reactor and a coolant composition for a nuclear reactor are also provided.

A method for controlling reactivity in a nuclear reactor is provided. The method comprises circulating coolant through the nuclear reactor. A composition of the coolant comprises water and gadolinium. The gadolinium is present in the coolant at a concentration suitable for controlling a neutronic reactivity of the nuclear reactor. A method for adjusting reactivity in a nuclear reactor and a coolant composition for a nuclear reactor are also provided.

A method for controlling a pressurized water reactor, computer program product and control system, the pressurized water reactor includes a reactor core and a primary cooling circuit. The primary cooling circuit includes a primary cooling medium, which includes: acquiring a plurality of measurable reactor process variables and obtaining a plurality of non-measurable reactor process variables. The method further includes calculating future axial offsets at the end of a predetermined prediction time interval for a plurality of different possible boration/dilution actions based on the plurality of measurable reactor process variables and the plurality of non-measurable reactor process variables, the axial offset being a normalized difference between power of an upper half of the reactor core and a lower half of the reactor core. The calculation of the future axial offset for each of the plurality of different possible boration/dilution actions is performed in parallel.

A method for controlling a pressurized water reactor, computer program product and control system, the pressurized water reactor includes a reactor core and a primary cooling circuit. The primary cooling circuit includes a primary cooling medium, which includes: acquiring a plurality of measurable reactor process variables and obtaining a plurality of non-measurable reactor process variables. The method further includes calculating future axial offsets at the end of a predetermined prediction time interval for a plurality of different possible boration/dilution actions based on the plurality of measurable reactor process variables and the plurality of non-measurable reactor process variables, the axial offset being a normalized difference between power of an upper half of the reactor core and a lower half of the reactor core. The calculation of the future axial offset for each of the plurality of different possible boration/dilution actions is performed in parallel.

A nuclear reactor shutdown system includes a housing vessel that is disposed above a reactor core fuel housed in a nuclear core vessel in a hermetically sealed manner, houses a plurality of neutron absorbers, and has an opening enabling the neutron absorbers to pass through at a bottom, a shielded path that passes through the reactor core fuel to extend in an up-and-down direction, an upper end of the shielded path communicating with the opening of the housing vessel and a lower end of the shielded path being closed, and a communicating part that is disposed so as to close the opening and causes the housing vessel and the shielded path to communicate with each other when the communicating part reaches or exceeds a threshold temperature.

A nuclear reactor shutdown system includes a housing vessel that is disposed above a reactor core fuel housed in a nuclear core vessel in a hermetically sealed manner, houses a plurality of neutron absorbers, and has an opening enabling the neutron absorbers to pass through at a bottom, a shielded path that passes through the reactor core fuel to extend in an up-and-down direction, an upper end of the shielded path communicating with the opening of the housing vessel and a lower end of the shielded path being closed, and a communicating part that is disposed so as to close the opening and causes the housing vessel and the shielded path to communicate with each other when the communicating part reaches or exceeds a threshold temperature.