Abstract: A reactor state monitoring apparatus including: a first gamma ray-dose measurement device that detects and measures an atmospheric radiation dose caused by radioactive substances on a containment vessel side respective to a biological shielding wall surrounding a pressure vessel and outside the pressure vessel; a second gamma ray-dose measurement device that detects and measures a radiation dose on the pressure vessel side respective to the biological shielding wall; a fuel radiation measuring device that detects and measures a radiation dose of fuel in the pressure vessel; and a water amount evaluation device that calculates a difference between radiation doses measured by the fuel radiation measuring device and the first gamma ray-dose measurement device as a corrected fuel radiation dose, and acquires a cooling water level as a water level evaluation value, based on the radiation dose measured by the second gamma ray-dose measurement device and the corrected fuel radiation dose.

Abstract: It is provided with a reactor water-level measurement system being possible to measure water-level in a reactor core regardless of a state in the reactor core. The reactor water-level measurement system includes a core bottom water-level measuring device that includes a heating element, a heat insulating element installed by surrounding part of the heating element in a height direction of the heating element, and a temperature difference measuring element that measures a temperature difference between an insulated portion of the heating element surrounded by the heat insulating element and a non-insulated portion not surrounded by the heat insulating element, a water-level evaluation device that evaluates a water level of a reactor based on the temperature difference, wherein the core bottom water-level measuring device measures at least a water level from a lower end of a reactor core contained in a reactor pressure vessel to a bottom of the reactor pressure vessel.

Abstract: A reactor state monitoring apparatus including: a first gamma ray-dose measurement device that detects and measures an atmospheric radiation dose caused by radioactive substances on a containment vessel side respective to a biological shielding wall surrounding a pressure vessel and outside the pressure vessel; a second gamma ray-dose measurement device that detects and measures a radiation dose on the pressure vessel side respective to the biological shielding wall; a fuel radiation measuring device that detects and measures a radiation dose of fuel in the pressure vessel; and a water amount evaluation device that calculates a difference between radiation doses measured by the fuel radiation measuring device and the first gamma ray-dose measurement device as a corrected fuel radiation dose, and acquires a cooling water level as a water level evaluation value, based on the radiation dose measured by the second gamma ray-dose measurement device and the corrected fuel radiation dose.

Abstract: It is provided with a reactor water-level measurement system being possible to measure water-level in a reactor core regardless of a state in the reactor core. The reactor water-level measurement system includes a core bottom water-level measuring device that includes a heating element, a heat insulating element installed by surrounding part of the heating element in a height direction of the heating element, and a temperature difference measuring element that measures a temperature difference between an insulated portion of the heating element surrounded by the heat insulating element and a non-insulated portion not surrounded by the heat insulating element, a water-level evaluation device that evaluates a water level of a reactor based on the temperature difference, wherein the core bottom water-level measuring device measures at least a water level from a lower end of a reactor core contained in a reactor pressure vessel to a bottom of the reactor pressure vessel.

Abstract: Each of APRM units equipped for each of the diversity channels has printed circuit boards having circuit patterns thereon and a circuit description elements installed on the printed circuit board. The circuit description elements are FPGA elements manufactured by mutually different providers for example and implemented an electric circuit described in a hardware description language by a configuration tool. The circuit description elements can be implemented mutually different descriptions of the electric circuit, or can be implemented the electric circuit by mutually different configuration tools. Also, the printed circuit boards for the diversity channels can be different from each other.

Abstract: Each of APRM units equipped for each of the diversity channels has printed circuit boards having circuit patterns thereon and a circuit description elements installed on the printed circuit board. The circuit description elements are FPGA elements manufactured by mutually different providers for example and implemented an electric circuit described in a hardware description language by a configuration tool. The circuit description elements can be implemented mutually different descriptions of the electric circuit, or can be implemented the electric circuit by mutually different configuration tools. Also, the printed circuit boards for the diversity channels can be different from each other.