A detector signal-processing circuit comprises the following: a current/voltage conversion part that converts the current value of a neutron detector to a voltage value; a variable gain amplification part that performs amplification by a first-step variable gain using a D/A converter; a current level response-use resistance circuit that selects the measurement range in accordance with the voltage value; temperature measurement units for measuring the temperature of the resistance circuit for current level response; a temperature compensation part for commanding gain compensation by the D/A converter on the basis of the measured temperature; and a selective adjustment control part for selective control of the measurement range and adjustment of the variable gain of the variable gain amplification part. Due to this configuration, neutron flux can be measured with high precision while maintaining a constant output precision, before and after switching of the measurement range.

A detector signal-processing circuit comprises the following: a current/voltage conversion part that converts the current value of a neutron detector to a voltage value; a variable gain amplification part that performs amplification by a first-step variable gain using a D/A converter; a current level response-use resistance circuit that selects the measurement range in accordance with the voltage value; temperature measurement units for measuring the temperature of the resistance circuit for current level response; a temperature compensation part for commanding gain compensation by the D/A converter on the basis of the measured temperature; and a selective adjustment control part for selective control of the measurement range and adjustment of the variable gain of the variable gain amplification part. Due to this configuration, neutron flux can be measured with high precision while maintaining a constant output precision, before and after switching of the measurement range.

A sensor assembly for determining an operating characteristic of a nuclear reactor. The sensor assembly includes a solid-state lasing media doped with a fissile species and disposable within a core of the nuclear reactor and an optical fiber operably coupled to the solid-state lasing media and configured to extend out of the core of the nuclear reactor and to control system of reactor. The fissile species include one or more of uranium, plutonium, americium, or californium. A method of determining an operating characteristic of a nuclear reactor includes during operation of the nuclear reactor; receiving from the optical fiber a laser light, analyzing the laser light, and based on the analysis of the laser light, determining the operating characteristic of the nuclear reactor.

A sensor assembly for determining an operating characteristic of a nuclear reactor. The sensor assembly includes a solid-state lasing media doped with a fissile species and disposable within a core of the nuclear reactor and an optical fiber operably coupled to the solid-state lasing media and configured to extend out of the core of the nuclear reactor and to control system of reactor. The fissile species include one or more of uranium, plutonium, americium, or californium. A method of determining an operating characteristic of a nuclear reactor includes during operation of the nuclear reactor; receiving from the optical fiber a laser light, analyzing the laser light, and based on the analysis of the laser light, determining the operating characteristic of the nuclear reactor.

A method is for controlling a nuclear power plant comprising pressurized water nuclear reactor (3) having a reactor core producing power, a primary circuit (5) connecting the reactor core to a steam generator (9), one or more of control rods (16), which can be moved into the reactor core for controlling the power of the reactor core, an injecting device (22, 23, 24, 26, 28, 30) for injecting boric acid and/or deionized water into the primary circuit (5) for controlling the reactivity of the reactor core.

A measuring system includes a detector having an optical waveguide including a primary dopant capable of transmuting, by neutron capture, into a stable secondary dopant that is less neutron-absorbent than the primary dopant, a moderation layer suitable for slowing down fast neutrons, and an analysis device connected to the detector. The analysis device is configured to inject, into the waveguide, an interrogation wave having a wavelength corresponding to an absorption peak of the secondary dopant, detect a response wave emitted by the waveguide, calculate, from the detected response wave, a piece of information relating to a concentration of secondary dopant in the waveguide, and, based on the information relating to the calculated concentration of secondary dopant, determine a fluence of fast neutrons during a predetermined secondary period.

A measuring system includes a detector having an optical waveguide including a primary dopant capable of transmuting, by neutron capture, into a stable secondary dopant that is less neutron-absorbent than the primary dopant, a moderation layer suitable for slowing down fast neutrons, and an analysis device connected to the detector. The analysis device is configured to inject, into the waveguide, an interrogation wave having a wavelength corresponding to an absorption peak of the secondary dopant, detect a response wave emitted by the waveguide, calculate, from the detected response wave, a piece of information relating to a concentration of secondary dopant in the waveguide, and, based on the information relating to the calculated concentration of secondary dopant, determine a fluence of fast neutrons during a predetermined secondary period.

Device for detecting neutrons with ionization chamber and with optical transduction comprising a plurality of optical cavities, each accommodating the free end of an optical fiber.

The invention relates to a device (1) for detecting neutrons comprising at least one sealed ionization chamber (2) and with optical transduction with a plurality of cavities whose operation is each based on optical transduction using an optical fiber whose free end is within the cavity, which allows multipoint neutron-flux measurement, the measurement points being axially distributed.

A neutron beam detecting device according to the invention includes: a first solar cell-type detector that is provided with, on a surface thereof, a conversion film for converting neutrons into photons or any charged particle beam among alpha particles, protons, lithium nuclei, gamma rays or beta rays, and generates a current in response to incident radiation; a radiation detector that generates a current insensitive to neutrons as an output signal in response to the radiation incident; a current measuring device that detects, as signals, the current generated by the first solar cell-type detector and the current generated by the radiation detector in response to the incident radiation; and a flux calculating unit that compares the current signals from the detectors which are detected by the current measuring device. The flux calculating unit associates the detected current signals from the solar cell-type detector and the radiation detector with a relation between a flux of incident radiation of a predetermined type obtained in advance and the detected currents from the solar cell-type detector and the radiation detector, and calculates a flux of a neutron beam.

A self-powered in-core detector arrangement for measuring flux in a nuclear reactor core includes a first in-core detector and a second in-core detector. The first in-core detector includes a first flux detecting material, a first lead wire extending longitudinally from a first axial end of the first flux detecting material, a first insulating material surrounding outer diameters of the first flux detecting material and the first lead wire and a first sheath surrounding the first insulating material. The first sheath includes a first section surrounding the first flux detecting material and a second section surrounding the first lead wire. The first section of the first sheath has a greater outer diameter than the second section of the first sheath. The second in-core detector includes a second flux detecting material, a second lead wire extending longitudinally from a first axial end of the second flux detecting material, a second insulating material surrounding outer diameters of the second flux detecting material and the second lead wire, and a second sheath surrounding the second insulating material. The second sheath includes a first section surrounding the second flux detecting material and a second section surrounding the second lead wire. The first section of the second sheath has a greater outer diameter than the second section of the second sheath. The first section of the first sheath is axially offset from the first section of the second sheath and radially aligned with the second section of second sheath.