JP2020071112A - Radiation monitor and method for measuring radiation - Google Patents

Abstract

To provide a radiation monitor for measuring a dosage rate with high accuracy even under a hot and high dosage rate environment.SOLUTION: In order to achieve the above objective, the present invention provides a radiation monitor comprising: a radiation detection unit 10 having a radiation detection element 11 for generating photons and emitting light upon incidence of radiation and a housing 12 for accommodating the radiation detection element; a light detection unit 70 for converting the photons generated by the radiation detection unit into an electric signal piece by piece; a measuring device 80 for calculating the dosage rate of radiation on the basis of the count rate of the electric signals; and a heating unit 21 for heating the radiation detection unit or its vicinity. The measuring device calculates a first count rate when a voltage is applied to the heating unit, calculates a second count rate when radiation enters the radiation detector, and converts a third count rate derived by subtracting the first count rate from the second count rate into the dosage rate of radiation.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radiation monitor for measuring a radiation dose rate and a radiation measuring method.

  Gas detectors, scintillation detectors, semiconductor detectors, and the like are known as conventional charged particle detectors.

  The gas detector has a structure in which a metal wire is installed in a container in which gas is sealed. The charged particles ionize the gas in the detector to generate electrons, which are amplified in a high electric field region near the metal wire and measured as an electric signal.

  The scintillation detector emits light from the scintillation element when charged particles are incident on the scintillation element, converts the emitted light into an electric signal using a photomultiplier tube or the like, and measures the charged particle based on the electric signal. Since a large number of photons are generated when one charged particle is incident, and the number of generated photons is proportional to the energy of the incident charged particles, the peak value of the pulse-shaped electric signal proportional to the number of generated photons. Is measured to measure the energy of the incident charged particles.

  In a semiconductor detector, an electron-hole pair generated by ionization by charged particles is generated in a region (depletion layer) formed around a junction surface where p-type and n-type semiconductors are joined, where electrons and holes are scarcely present. , A detector that detects charged particles based on electric signals generated by moving to p-type and n-type, respectively. Since a large number of electron-hole pairs are generated when one charged particle is incident, and the number of generated electron-hole pairs is proportional to the energy of the incident charged particles, it is proportional to the number of generated electron-hole pairs. The energy of the incident charged particles is measured by measuring the peak value of the pulsed electric signal.

JP, 2017-15662, A JP, 2016-114392, A

  However, when these charged particle beam detectors are used in a high dose environment, there are the following problems.

  In the case of a gas detector, gamma rays incident on the gas detector and many electrons due to Compton scattering between the gas and the detector container material are measured, so that it is difficult to distinguish them from charged particles.

  In the case of a scintillation detector, a large number of gamma rays are incident on the scintillation element at the same time, and pulsed electric signals overlap each other, which makes it difficult to correctly measure charged particles. In order to prevent this, if the periphery of the scintillation element is covered with a radiation shield such as lead, charged particles cannot enter the detector, which makes it difficult to use.

  In the case of a semiconductor detector, a large number of gamma rays are incident on the semiconductor element at the same time, and pulsed electric signals overlap each other, which makes it difficult to correctly measure charged particles. If the periphery of the semiconductor element is covered with a radiation shield such as lead in order to prevent this, charged particles cannot enter the detector, which makes it difficult to use.

  Regarding detectors for detecting neutron rays, gas detectors, scintillation detectors, semiconductor detectors, and the like are known as well as charged particle detectors. However, similar to the charged particle detector described above, measurement in a high dose rate environment was difficult.

  On the other hand, as a radiation monitor that can be measured in a high dose rate environment, there are techniques described in Patent Document 1 and Patent Document 2, for example. These documents describe a technique of transmitting light emitted from a radiation detection element through an optical fiber and measuring a dose rate based on the count rate of each photon.

  However, when the radiation monitor is used in a high temperature environment, there is a background due to radiation, so a correction method for it is necessary. Patent Document 1 describes a method of performing correction using a plurality of wavelengths, but a system for measuring each photon of a plurality of wavelengths is required, and the system becomes complicated. Moreover, there is no description of a technique for confirming and evaluating a background change due to radiation due to deterioration of a radiation monitor during plant operation.

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a radiation monitor that accurately measures a dose rate even under a high temperature and high dose rate environment.

  In order to solve the above problems, one of the representative aspects of the present invention is "a radiation detection element having a radiation detection element that generates a photon and emits light when radiation enters, and a radiation detection section having a housing that houses the radiation detection element, The photodetector that converts each photon generated by the radiation detector into an electric signal, the measuring device that calculates the radiation dose rate based on the count rate of the electric signal, and the radiation detector or the vicinity thereof. A radiation monitor comprising: a heating unit for heating; the measuring device calculates a first count rate when a voltage is applied to the heating unit, and a second counting rate when the radiation enters the radiation detector. A radiation monitor characterized by calculating a counting rate and converting a third counting rate obtained by subtracting the first counting rate from the second counting rate into a radiation dose rate. "

  According to the present invention, it is possible to provide a radiation monitor that shows a correct dose rate even in a high temperature and high dose rate environment.

It is a block diagram of the radiation monitor which concerns on Example 1 of this invention. It is explanatory drawing of the relationship between the count rate of each photon and the wavelength of a photon by thermal radiation (radiation). It is explanatory drawing of the relationship between the count rate of each photon and the electric power applied to a heating part, when a dose rate is made constant. It is explanatory drawing of the method of calculating the dose rate which removed the influence of the photon produced by thermal radiation. It is a block diagram of the radiation monitor which concerns on Example 2 of this invention. An example of the counting rate of each photon with respect to the measured value of temperature. It is a block diagram of the radiation monitor which concerns on Example 3 of this invention. It is explanatory drawing of the time-dependent change of the count rate of each photon with respect to the electric power given to a heating part. It is explanatory drawing of the time change of the count rate of each photon and the power application to a heating part when a radiation light emitting element part is in water or air. It is a block diagram of the radiation monitor which concerns on Example 6 of this invention. It is a block diagram of the radiation monitor which concerns on Example 7 of this invention. It is a block diagram of the radiation detection part which concerns on Example 7 of this invention.

  Examples suitable for carrying out the present invention will be described below. It should be noted that the following is merely an example of the embodiment, and the invention itself is not intended to be limited to the following specific contents.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A first embodiment of the present invention will be described with reference to FIGS.

  First, the configuration of the radiation monitor according to the present embodiment will be described. 1 is a configuration diagram of a radiation monitor according to a first embodiment of the present invention.

  The radiation monitor 1 according to the present embodiment includes a radiation detection unit 10 that emits light when radiation enters, a heating device 20 that heats the radiation detection unit 10, an optical fiber 40, a light detection unit 70, and a measurement device 80. An analysis / display device 90 is provided.

  The radiation detection unit 10 includes a radiation light emitting element 11 formed of a member obtained by adding a rare earth element to a ceramic base material, and a detector housing 12 that houses the radiation light emitting element 11. The radiation detection unit 10 is installed in a measurement area that measures radiation.

  The radiation emitting element 11 is formed of a light-transmitting material such as transparent yttrium-aluminum-garnet as a ceramic base material and a rare earth element such as ytterbium, neodymium, cerium or praseodymium contained in the light-transmitting material. ing. The light emission time of the radiation emitting element 11 (for example, yttrium-aluminum-garnet is YAG: Nd which is a material containing neodymium) has a longer optical decay time than that of NaI, BGO, or plastic scintillator used in conventional radiation detectors. You have selected one.

  The heating device 20 includes a heating unit 21, an electric wire 22, and a voltage control device 23.

  The heating unit 21 is, for example, a heater or the like, and is installed near the radiation detection unit 10 or the heating unit 21.

  The voltage control device 23 controls the voltage applied to the heating unit 21.

  The optical fiber 40 connects the radiation detection unit 10 and the light detection unit 70. More specifically, one end of the optical fiber 40 is connected to the radiation emitting element 11, and the other end of the optical fiber 40 is connected to the photodetector 70. In addition, in the matter that the optical fiber 40 is “connected” to the radiation emitting element 11, in addition to the configuration in which one end of the optical fiber 40 is in close contact with the radiation emitting element 11, one end of the optical fiber 40 is connected to the radiation emitting element 11. Includes configurations that are in close proximity.

  The light detection unit 70 converts light (pulse light) guided to itself via the optical fiber 40 into an electric signal (light detection processing). More specifically, when one photon enters the photodetector 70, one electrical signal (pulse signal) is generated by photoelectric conversion. As such a photodetector 70, for example, a photomultiplier tube or a photodiode can be used.

  The measuring device 80 is a device that measures the count rate of the electric signal input from the photodetection unit 70, and is connected to the photodetection unit 70 via the wiring k1. Although not shown, the measuring device 80 is configured to include electronic circuits such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and various interfaces. Then, the program stored in the ROM is read and expanded in the RAM, and the CPU executes various processes.

  The analysis / display device 90 is connected to the measuring device 80 via the wiring k2. Although not shown, it is configured to include electronic circuits such as a CPU, a ROM, a RAM, and various interfaces. The analysis / display device 90 calculates the radiation dose rate based on the count rate of the electric signals input from the measurement device 80 (analysis process), and displays the calculation result. The count rate of the electric signal and the radiation dose rate are in a proportional relationship, and the proportional coefficient is stored in advance in the analysis / display device 90.

  Next, the measurement principle and operation of the radiation monitor according to the present embodiment will be described.

  It is known that the dose rate of the radiation incident on the radiation detection element 11 and the number of photons generated by the radiation detection element 11 per unit time are in a proportional relationship. That is, the dose rate of the radiation incident on the radiation detection element 11 and the count rate of the electric signal (pulse signal) converted by the photodetection unit 70 are in a proportional relationship. Therefore, in the present embodiment, based on such a proportional relationship, the number (counting rate) of the electric signals output from the photodetecting section 70 to the measuring device 80 per unit time is converted into the radiation dose rate, and the dose is calculated. Calculate the rate. The details will be described below.

  When radiation or light is incident on the radiative light emitting element 11, electrons or rare earth atoms in the radiation light emitting element 11 transit to an excited state having a high energy level. Photons are generated when transitioning from the high excited state to the low energy level excited state or the ground state.

  The photons generated by the radiation emitting element 11 pass through the optical fiber 40 and are detected by the photodetector 70. The photodetector 70 detects each photon and converts it into an electric signal (pulse signal).

  When the number of photons generated by the radiation detection element 11 per unit time (the total number) exceeds the upper limit value at which the photodetection unit 70 can perform photoelectric conversion, that is, the photodetection unit 70 has many photons. An optical attenuation filter (not shown) may be additionally provided when incident and converting a plurality of photons into one electric signal. For example, a light attenuation filter may be provided in the front stage of the light detection unit 70. Further, the type of the radiation detection element 11 and the material / thickness of the housing 12 may be appropriately selected so that the optical attenuation filter becomes unnecessary. As a result, each photon incident on the photodetector 70 can be converted into an electric signal.

  In addition, by installing the wavelength selection unit in the preceding stage of the photodetection unit 70, it becomes possible to transmit photons of only a specific wavelength. As the wavelength selection unit, one or a plurality of wavelength selection filters may be used, or a spectroscope may be used.

  After being converted into an electric signal by the photodetector 70, the counting rate of this electric signal is measured by the measuring device 80. There is a proportional relationship between the dose rate in the radiation detection unit 10 and the count rate of this electric signal. The analysis display device 90 derives the dose rate from the count rate using the proportional coefficient of the dose rate and the count rate measured in advance.

  Here, when the installation environment temperature of the radiation detection unit 10 rises, photons are generated from the constituent members of the radiation detection unit 10 by thermal radiation (radiation). FIG. 2 is an explanatory diagram of the relationship between the count rate of each photon due to thermal radiation (radiation) and the wavelength of the photon. In the figure, light emission by radiation is also shown. The rate of generation of photons due to thermal radiation (radiation) increases as the installation environment temperature increases and the wavelength of photons increases. As the installation environment temperature rises, the background, which is a photon due to thermal radiation (radiation), rises, and it becomes impossible to accurately measure a photon having a wavelength emitted by irradiation of radiation. At this time, in order to derive the dose rate due to radiation, it is necessary to correct the influence of photons due to thermal radiation.

  Therefore, the radiation monitor according to the present embodiment derives the count rate excluding the influence of photons generated by thermal radiation by the method described below.

  First, the heating unit 21 heats the radiation detection unit 10. At this time, photons are generated from the radiation detection unit 10 according to the voltage applied to the heating unit 21 by the voltage control device 23. The photodetector 70 detects the generated photons and converts them into electric signals. The measuring device 80 measures the count rate of the converted electric signal.

  FIG. 3 is an explanatory diagram of the relationship between the count rate of each photon and the power applied to the heating unit 21 when the dose rate of radiation is constant. Since the generation rate of photons due to thermal radiation (radiation) depends on the temperature of the radiation detection unit 10 and the temperature of the radiation detection unit 10 depends on the electric power applied to the heating unit 21, the radiation detection unit 10 is set by the heating unit 21. When heated, the photon count rate, which changes according to the change in the applied power from the voltage controller 23, is as shown in FIG. 3, for example. The relationship between the photon count rate and the applied voltage at this time, that is, the relationship between the photon generation rate due to thermal radiation (radiation) and the applied voltage is stored in advance in, for example, the analysis display device 90, and the measured value is used. Is corrected as follows.

  FIG. 4 is an explanatory diagram of a method of calculating a dose rate excluding the influence of photons generated by thermal radiation when actually measured in a radiation environment and a high temperature environment. The measurement values of the count rate under the radiation environment and the high temperature environment include the count rate by radiation and the count rate by thermal radiation. Therefore, the analysis display device 90 derives the count rate of radiation by subtracting the count rate of thermal radiation from the measured value of the count rate. Here, as the counting rate due to heat radiation, a value stored in advance or input using an external input device (not shown) or the like is used. Then, it is possible to convert the dose rate into a dose rate by using the proportional coefficient of the dose rate and the count rate measured in advance, and to calculate the dose rate without the influence of photons generated by thermal radiation.

  FIG. 4 shows the case where the counting rate due to radiation is constant, but similarly when the counting rate due to radiation changes, the counting rate due to thermal radiation (radiation) is also subtracted from the counting rate under radiation and high temperature environment. By doing so, the counting rate due to radiation can be measured, and the dose rate excluding the effect of photons generated by thermal radiation can be calculated.

  The second embodiment is different from the first embodiment in that the radiation monitor includes a thermometer side portion, a signal line, a temperature measurement control device, and a database. In addition, this embodiment is different from the first embodiment in that the value of the count rate of each photon with respect to the temperature measurement value is measured and recorded in the database before the radiation monitor is used for measuring radiation. The other points are the same as in the first embodiment. Therefore, only the parts different from the first embodiment will be described, and the description of the overlapping parts will be omitted.

  FIG. 5 is a configuration diagram of a radiation monitor according to the second embodiment of the present invention.

  The radiation monitor 1 according to the present embodiment further includes a thermometer side portion 24, a signal line 25, a temperature measurement control device 26, and a database 27.

  The temperature measurement unit 24 is a sensor or the like that measures temperature, and is installed near the radiation detection unit 10. The installation position may be inside the housing 12 or outside the housing 12. The temperature measured by the temperature measurement unit 24 is transmitted to the temperature measurement control device 26 via a signal line 25 connecting the thermometer side unit 24 and the temperature measurement control device 26.

  The database 27 records the relationship between the measured value of the temperature measured by the thermometer side part 24 and the count rate of the electric signal obtained by converting each photon due to thermal radiation (radiation) measured by the measuring device 80.

  FIG. 6 shows an example of the counting rate of each photon with respect to the measured value of temperature.

  Before the radiation monitor 1 is used for radiation measurement, the radiation detector 10 is heated using the heating unit 21. The voltage controller 23 changes the voltage applied to the heating unit 21 to change the temperature of the heating unit 21, and the thermometer side unit 24 measures the temperature in the vicinity of the radiation detection unit 10 or the heating unit 21.

  As the measured value of the temperature in the vicinity of the radiation detection unit 10 or the heating unit 21 measured by the thermometer side unit 24 rises, electricity converted from each photon by thermal radiation (radiation) measured by the measuring device 80 The signal count rate increases.

  The database 27 records the counting rate of each photon with respect to the measured value of the temperature measured by the thermometer side part 24.

  The radiation monitor according to the present embodiment measures and records the counting rate of each photon for each temperature measurement value in the vicinity of the radiation detection unit 10 in advance, so that the temperature can be measured during radiation measurement by the radiation monitor. It is possible to derive the count rate due to thermal radiation (radiation) using the data recorded in the database from the measured value of the temperature measured.

  As a result, the count rate due to radiation is derived by subtracting the count rate due to thermal radiation from the measured count rate, and converted to a dose rate by using the proportional coefficient between the dose rate and the count rate measured in advance. , It is possible to calculate the dose rate excluding the effect of photons generated by thermal radiation.

  The third embodiment is different from the first embodiment in that the radiation monitor includes a light irradiation device, a light irradiation control device, a light branching unit, and a light branching optical filter. The other points are the same as in the first embodiment. Therefore, only the parts different from the first embodiment will be described, and the description of the overlapping parts will be omitted.

  FIG. 7 is a configuration diagram of a radiation monitor according to the third embodiment of the present invention.

  The radiation monitor 1 according to the present embodiment further includes a light irradiation device 50, a light irradiation control device 51, a light branching unit 60, and a light branching optical filter 61.

  The light irradiation device 50 is a semiconductor laser used when determining whether or not the radiation monitor 1 is functioning normally. An LED (Light Emitting Diode) may be used as the light irradiation device 50. The light irradiation device 50 emits light having a wavelength different from the emission wavelength of the radiation detection element 11.

  The light branching unit 60 branches the light from the radiation detection unit 10 toward the light irradiation device 50 and the light detection unit 70.

  The light irradiation control device 51 is a device that controls the light emission intensity of the light irradiation device 50, the pulse length and the light emission frequency during continuous light emission or pulse light emission, and is connected to the light irradiation device 50 via wiring. There is. Although not shown, the light irradiation control device 51 is configured to include electronic circuits such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and various interfaces. Then, the program stored in the ROM is read and expanded in the RAM, and the CPU executes various processes. The processing executed by the light irradiation control device 51 will be described later.

  The radiation detection unit 10 is connected to the light irradiation device 50 and the light detection unit 70 through an optical fiber and an optical branching unit 60 installed in the subsequent stage of the optical fiber.

  Next, the operation of the radiation monitor according to the present embodiment will be described.

  The wavelength of the light irradiated using the light irradiation device 50 is set to a wavelength different from the wavelength of the light generated by irradiating the radiation light emitting element 11 with the light. When the light emitted from the light irradiation device 50 is applied to the radiation emitting element 11 via the optical fiber and the light branching unit 60, the radiation emitting element 11 generates a number of photons proportional to the intensity of the applied light. It The generated photons and the photons reflected and scattered by the irradiated light in the radiation detection unit 10 are combined and enter the wavelength selection unit via the optical fiber and the optical branching unit 60.

  In the wavelength selection unit, only photons of the wavelength emitted by the radiation emitting element 11 are incident on the photodetection unit 70.

  The photodetector 70 converts the detected photons into an electric signal.

  The measuring device 80 measures the count rate of the electric signal output from the photodetector 70. The operation of the radiation monitor is checked and calibrated by using the relationship between the intensity of light from the light emitting unit and the count rate measured in advance.

  When inspecting the radiation monitor 100G, the analysis / display device 90 executes predetermined processing based on the light intensity of the light irradiation device 50 and the count rate of electric pulses. That is, the analysis / display device 90 determines whether the light irradiation device 50 has deteriorated or other components (the radiation detection element 11, the optical fiber 40, etc.) have deteriorated, and displays the determination result. As a result, the reliability of the radiation monitor 1 can be increased more than ever before.

  The fourth embodiment is different from the second embodiment in that the change over time of the count rate of the radiation monitor is calibrated. The other points are the same as in the second embodiment. Therefore, only the parts different from the second embodiment will be described, and the description of the overlapping parts will be omitted.

  FIG. 8 shows an example of changes over time in the counting rate of each photon with respect to the electric power applied to the heating unit.

  Before the radiation monitor 1 is used for radiation measurement, even if the database of the counting rate of each photon with respect to the voltage applied to the heating unit 21 is made from the voltage control device 23, the power supplied to the heating unit 21 during use The count rate of each photon with respect to can vary.

  Therefore, in the present embodiment, for example, when performing maintenance on the radiation monitor 1, there is no heat radiation (radiation) from the measured value of the count rate of each photon when the voltage applied to the heating unit 21 is changed. Alternatively, the count rate of heat radiation (radiation) when the voltage applied to the heating unit 21 is changed is derived by subtracting the count rate of each photon in the range of very small amount of electricity, and stored in the database 27. save.

  With this, the radiation count rate is derived based on the latest database, and this count rate and the dose rate measured in advance and the proportional coefficient of the count rate are used to convert the dose rate into a dose rate. Even in such a case, the counting rate due to thermal radiation can be accurately corrected.

  The fifth embodiment is different from the second embodiment in that it is determined whether the radiation monitor is in water or in the air based on the count rate of the radiation detection unit. The other points are the same as in the second embodiment. Therefore, only the parts different from the second embodiment will be described, and the description of the overlapping parts will be omitted.

  FIG. 9 shows an example of the relationship between the time change of the counting rate of each photon and the power application to the heating unit 21 when the radiation detection unit 10 is in water or in the air.

  In the present embodiment, when the radiation detection unit 10 is installed in water and in the air in advance, one photon before the application of voltage to the heating unit 21, before application of voltage, during application, application stop, and application stop The change of one count rate is measured and stored in the database 27.

  When the change in the counting rate of each photon before the application of power to the heating unit 21, before the application of the power, during the application of the power, after the application of the power is stopped, and when the application of the power is stopped, when the radiation detection unit 10 is in water, Compared to the case, the heat transfer rate around the radiation detection unit 10 is high, so the rate of increase of the count rate of each photon is slow and the maximum count rate is also low. Moreover, the rate of decrease of the count rate after the application is stopped also becomes slow.

  Based on the measured data of the count rate increase rate, the maximum count rate, and the count rate decrease rate of each photon, and the database measured in advance, whether the radiation detection unit 10 is in water or in air. It can be determined whether or not.

  The sixth embodiment differs from the second embodiment in that the heating unit 21 is a laser heating device.

  FIG. 10 is a configuration diagram of a radiation monitor according to the sixth embodiment of the present invention.

  In this embodiment, a laser heating device is used as the heating unit 21. The laser heating device is connected to the radiation detection unit 10 via an optical fiber 40.

  The laser light generated by the laser heating device is applied to the radiation detection unit 10 through the optical fiber 40. Here, the structure is such that the irradiated laser light does not enter the optical fiber that optically connects the radiation detection unit 10 and the light branching unit 70. The temperature of the radiation detection unit 10 is changed by changing the intensity of the laser light applied to the radiation detection unit 10 and the irradiation time of the laser light. The thermometer side part 24 measures the temperature in the vicinity of the radiation detection part 10. The database 27 records the relationship between the measured value of the temperature measured by the thermometer side part 24 and the count rate of the electric signal obtained by converting each photon by thermal radiation (radiation) measured by the measuring device 80. Then, record the count rate of radiation due to thermal radiation in advance.

  As a result, the count rate due to thermal radiation is subtracted from the count rate measurement value, the count rate due to radiation is derived, and converted into a dose rate by using the proportional coefficient between the dose rate and the count rate measured in advance. The dose rate can be calculated without the effects of photons produced by the radiation.

  The seventh embodiment is different from the sixth embodiment in the structure of the radiation detection unit. The other points are the same as in the second embodiment. Therefore, only the parts different from the second embodiment will be described, and the description of the overlapping parts will be omitted.

  11 is a configuration diagram of a radiation monitor according to a seventh embodiment of the present invention, and FIG. 12 is a configuration diagram of a radiation detection unit according to the seventh embodiment of the present invention.

  In this embodiment, the side surface of the radiation emitting element 11 which is not connected to the optical fiber 40 is covered with a metal or the like having a low heat radiation (emissivity) rate. This is the inside. In addition, the side surface of the radiation emitting element 11 is covered with a substance having a high heat emission (emissivity) from the outside such as a metal having a low heat emission (emissivity). This is the outer surface. In this embodiment, the surface of the radiation emitting element 11 that is in contact with the optical fiber 40 is called the bottom surface, and the other surfaces are called the side surfaces.

  The radiation emitting element 11 has an optical fiber for transmitting photons generated by the radiation emitting element 11 to generate light, and a laser heating device (heating unit 21) for heating the radiation emitting element 11. The optical fiber and the optical fiber for measuring the temperature in the temperature measuring unit 24 are connected.

  The outer surface of the radiation emitting element 11 is irradiated with laser light from the laser heating device that is the heating unit 21. At this time, heating efficiency is improved by irradiating a substance having a high heat radiation (radiation) rate, and heat radiation from the outer surface (radiation rate) is achieved by shielding the light by the inner surface of a metal having a low heat radiation (radiation) rate. ) Does not mix in the radiation emitting element 11. Further, since the heat radiation (radiation) from the inner surface of a metal or the like having a low heat radiation (radiation) rate is small, the background of the heat radiation (radiation) in the radiation measurement can be suppressed to be small. Further, the temperature measuring unit 24 measures the heat radiation rate from the outer surface of the radiation measuring element 11 through the temperature measuring optical fiber. By measuring the heat radiation (radiation) intensity from a known substance having a high heat radiation (radiation) rate, it becomes possible to measure the temperature with high accuracy.

DESCRIPTION OF SYMBOLS 10 ... Radiation detection part, 11 ... Radiation emitting element, 12 ... Detector housing, 20 ... Heating device, 21 ... Heating part, 22 ... Electric wire, 23 ... Voltage control device, 24 ... Temperature measuring part, 25 ... Signal line, 26 ... temperature measurement control device, 27 ... database, 40 ... optical fiber, 50 ... light irradiation device, 51 ... light emitting unit control device, 60 ... optical branching unit, 61 ... optical branching optical filter, 70 ... photodetecting unit, 80 ... Measuring device, 90 ... Analysis / display device

Claims (10)

A radiation detection unit having a radiation detection element that generates photons and emits light when radiation enters, and a radiation detection unit having a housing that houses the radiation detection element,
A photodetector for converting each photon generated by the radiation detector into an electric signal;
Based on the count rate of the electrical signal, a measuring device for calculating the radiation dose rate,
A heating unit that heats the radiation detection unit or the vicinity thereof,
A radiation monitor comprising:
The measurement device calculates a first count rate when a voltage is applied to the heating section, calculates a second count rate when radiation enters the radiation detection section, and calculates the second count rate. A radiation monitor, wherein a third count rate obtained by subtracting the first count rate from the above is converted into a radiation dose rate. A voltage control device that applies a voltage to change the temperature of the heating unit,
The radiation monitor according to claim 1, further comprising: a database that records the relationship between the voltage applied to the heating unit and the first count rate. A temperature measuring unit for measuring the temperature in the vicinity of the radiation detecting unit,
The radiation monitor according to claim 1 or 2, further comprising: a database that records a relationship between the measured value of the temperature measured by the temperature measuring unit and the first count rate. The measurement device calculates a fourth count rate when the voltage applied to the heating unit is 0,
According to the difference between the first count rate and the fourth count rate recorded in the database, the voltage applied to the heating section recorded in the database or the measured value of the temperature measured by the temperature measuring section and the The radiation monitor according to claim 2 or 3, wherein a relationship with the first count rate is calibrated. An irradiation device for irradiating the radiation emitting element with light having a wavelength different from the wavelength of light emitted by the radiation emitting element,
The radiation monitor according to any one of claims 1 to 4, further comprising a wavelength selection filter that transmits light having a wavelength generated by the radiation emitting element by the light with which the irradiation device is irradiated. The measurement device is configured to detect the radiation from the change in the counting rate of at least one photon before heating in the heating unit, when starting heating, during heating, when stopping heating, and after stopping heating. The radiation monitor according to any one of claims 1 to 5, wherein it is determined whether the part is in air or in water.   The radiation monitor according to claim 1, wherein the heating unit heats the radiation detection unit by irradiating the radiation detection unit with the generated laser light through an optical fiber.   The radiation monitor according to claim 7, wherein the heating unit changes the temperature of the radiation detection unit by changing the intensity of the laser light or the irradiation time of the laser light with which the radiation detection unit is irradiated.   The radiation emitting element has a side surface covered with a metal having a first thermal emissivity, and a metal having a second thermal emissivity larger than the first thermal emissivity from the outside of the metal having the first thermal emissivity. The radiation monitor according to claim 7 or 8, characterized in that. Generating a photon and emitting light when radiation enters the radiation emitting element;
Converting each photon generated by the radiation detection unit into an electric signal;
Calculating a radiation dose rate based on the count rate of the electrical signal;
A method of measuring radiation, comprising:
A first count rate is calculated when the radiation emitting element is heated, a second count rate is calculated when radiation enters the radiation emitting element, and the first count rate is calculated from the second count rate. A method for measuring radiation, comprising converting a third count rate, which is a count rate, into a radiation dose rate.

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