Abstract: An object is to change reactor core thermal output. A nuclear reactor includes an annular fuel layer and a heat conductive layer stacked on the fuel layer and extending around a periphery of the fuel layer.

Abstract: An object is to efficiently take heat out of a reactor core while retaining fission products. Included are fuel part provided with a covering part on a surface of a nuclear fuel and a heat conductive part.

Abstract: Provided is a nuclear reactor unit that can reduce a temperature increase in a reactor core at the occurrence of an abnormality with a simple structure. Included are a reactor core having radioactive fuel and causing the radioactive fuel to cause a nuclear reaction and a nuclear reactor vessel housing the reactor core and hermetically sealing the reactor core. The nuclear reactor vessel includes an inner shroud covering the entire periphery of the reactor core and an outer shroud covering the entire periphery of the inner shroud. A first space formed by the outer shroud and the inner shroud is in a vacuum condition. The inner shroud includes a main body and a communicating part placed in part of the main body and communicating the first space to a second space, which is a space inside the inner shroud, when the reactor core reaches a threshold temperature or higher.

Abstract: Heat can be stably extracted with easy criticality control. A nuclear reactor includes: a fuel portion being a reactor core having a nuclear fuel body; a shielding portion covering all over outer sides of the fuel portion to shield against radiations generated from the reactor core; and a thermal conduction part that conducts heat generated in the reactor core to exterior of the shield part. The nuclear fuel body contains a fissile material with an enrichment not less than 5% by weight throughout an operation period.

Abstract: Ensuring a high output temperature while preventing leakage of radioactive substances, etc. A nuclear reactor includes a fuel unit; a shield unit that covers a circumference of the fuel unit for shielding from radioactive rays; and a heat conductive portion that penetrates the shield unit, is arranged such that the heat conductive portion extends to inside of the fuel unit and outside of the shield unit, and transfers heat of the fuel unit to the outside of the shield unit by solid heat conduction.

Abstract: A nuclear power generation system includes a nuclear reactor that includes a reactor core fuel and a nuclear reactor vessel, the nuclear reactor vessel covering a surrounding of the reactor core fuel, shielding a space in which the reactor core fuel is present, and shielding radioactive rays; a heat conductive portion that is disposed in at least a part of the nuclear reactor vessel to transfer heat inside the nuclear reactor vessel to an outside by solid heat conduction; a heat exchanger that performs heat exchange between the heat conductive portion and a refrigerant; a refrigerant circulation unit that circulates the refrigerant passing through the heat exchanger; a turbine that is rotated by the refrigerant circulated by the refrigerant circulation unit; and a generator that rotates integrally with the turbine.

Abstract: A critical heat flux prediction device, a critical heat flux prediction method, a safety evaluation system, and a core monitoring system using the safety evaluation system can predict critical heat flux in a core of a reactor with a high degree of accuracy by obtaining a correlation plot distribution representing a relation of critical heat flux on a thermal equilibrium quality based on experimental data, approximating a correlation plot distribution through a logistic function that is a model function in which critical heat flux is expressed by a function of a thermal equilibrium quality, and obtaining a critical heat flux correlation of critical heat flux and a thermal equilibrium quality.

Abstract: A critical heat flux prediction device, a critical heat flux prediction method, a safety evaluation system, and a core monitoring system using the safety evaluation system can predict critical heat flux in a core of a reactor with a high degree of accuracy by obtaining a correlation plot distribution representing a relation of critical heat flux on a thermal equilibrium quality based on experimental data, approximating a correlation plot distribution through a logistic function that is a model function in which critical heat flux is expressed by a function of a thermal equilibrium quality, and obtaining a critical heat flux correlation of critical heat flux and a thermal equilibrium quality.