JP2018205070A - Radiation measurement device - Google Patents

Abstract

To provide a compact radiation measurement device capable of correctly specifying a position of a measurement object.SOLUTION: A radiation measurement device 1 of the present invention is a radiation measurement device capable of measuring a position at which a measurement object b such as a spent nuclear fuel including a radioactive material exists, and includes: a gamma ray collimator 111 having a substantially cylindrical shaped cylindrical body 112 which reduces a gamma ray and permits incidence of neutrons; a radiation detector 210 connected to this gamma ray collimator 111 and having a neutron converter 212 sensitive to thermal neutrons and measuring an energy imparted by the gamma ray and the thermal neutrons; a gamma ray shield body 311 provided so as to cover a region other than the gamma ray collimator 111; a neutron absorbing element 312 provided so as to cover the region other than the gamma ray collimator 111; and a neutron moderator 411 filled inside the cylindrical body 112.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radiation measuring apparatus.

  For example, in a place where nuclear fuel material with unknown characteristics is deposited, it is necessary to accurately grasp the position where the nuclear fuel material is present and its radioactivity in order to manage it safely. As a method for detecting such nuclear fuel material, for example, γ-rays from Eu-154 etc. emitted from radioactive materials present accompanying the nuclear fuel material, spontaneous fission of Cm-244 and (α, n) A method for measuring neutrons and the like generated in the reaction is known.

  Under such circumstances, the above-described apparatus for measuring γ-rays includes a scintillation detector, a detector that performs energy analysis using a semiconductor detector, etc., and a device that measures neutrons includes a fission ionization chamber, a scintillator, etc. There is a known detector that uses the two types of detectors, and a technique for measuring an index related to radioactivity such as burnup by using these two types of detectors together is disclosed (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 2006-121896

  However, the place where nuclear fuel material with unknown characteristics is deposited is usually near the containment vessel in the reactor building, and in such a place, the structure is complicated and there are many narrow parts. In addition, it is difficult to simultaneously operate a plurality of types of detectors as described above in terms of the volume and weight of the apparatus, and in addition, the use of a plurality of detectors may cause errors in the installation position and measurement range of the device. There is.

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a radiation measuring apparatus that is compact and capable of accurately specifying the position of a measurement object.

The present invention
(1) A radiation measurement device capable of measuring the location of a measurement object such as spent nuclear fuel containing radioactive material,
A γ-ray collimator having a substantially cylindrical cylindrical body that narrows incident γ-rays and allows neutrons to enter;
A radiation detector connected to the γ-ray collimator, having a neutron converter sensitive to thermal neutrons and measuring the energy imparted by γ-rays and thermal neutrons;
A γ-ray shield that is provided so as to cover a portion other than the γ-ray collimator of the radiation detector and shields the incidence of γ-rays other than γ-rays through the γ-ray collimator;
A neutron absorbing material that is provided so as to cover a portion other than the γ-ray collimator of the radiation detector and absorbs neutrons irradiated to the radiation detector,
A neutron moderator that fills the inside of the cylindrical body and converts fast neutrons emitted from the measurement object into thermal neutrons,
(2) The radiation measuring apparatus according to (1), wherein the neutron moderator is coated with a neutron absorber.
(3) The radiation measuring apparatus according to (1) or (2), further including a shutter capable of opening and closing the incidence of γ rays and neutrons to the γ ray collimator,
(4) In any one of (1) to (3), a distance meter capable of measuring a distance between the measurement object and the radiation detector is provided, and radiation is measured based on the distance measured by the distance meter. The radiation measuring device described,
(5) A radiation measurement device capable of measuring the location of a measurement object such as spent nuclear fuel containing radioactive material,
A plurality of γ-ray collimators having a substantially cylindrical body that narrows incident γ-rays and allows neutrons to enter;
These multiple γ-ray collimators are arranged two-dimensionally,
A plurality of radiation detectors connected to each of the plurality of γ-ray collimators, having a neutron converter sensitive to thermal neutrons and measuring energy imparted by γ-rays and thermal neutrons;
A γ-ray shield that is provided so as to cover a portion other than the plurality of γ-ray collimators of the plurality of radiation detectors and shields the incidence of γ-rays other than γ-rays through each of the plurality of γ-ray collimators;
A neutron absorber that is provided so as to cover a portion other than the plurality of γ-ray collimators of the plurality of radiation detectors, and that absorbs neutrons irradiated to the plurality of radiation detectors;
A neutron moderator that fills the inside of the cylindrical body and converts fast neutrons emitted from the measurement object into thermal neutrons,
(6) A detection ratio calculation device that calculates a ratio between a count value of γ rays detected by the radiation detector and a count value derived from thermal neutrons, and a burnup calculation device that calculates the burnup from the calculated ratio The radiation measuring apparatus according to any one of (1) to (5), further comprising:
(7) a distance meter capable of measuring the distance between the measurement object and the radiation detector;
A detection efficiency database in which data of detection efficiency of γ-rays and thermal neutrons are stored in advance;
The distance measured by the distance meter, the count value of γ rays and the count value derived from thermal neutrons measured by a radiation detector, the data of the detection efficiency of γ rays and thermal neutrons stored in the detection efficiency database, and The radiation measurement apparatus according to (6), including a radioactivity calculation device that calculates the radioactivity of the measurement object using a burnup degree,
(8) The radiation measurement apparatus according to any one of (1) to (7),
A photographing device for photographing surrounding images;
A radiation measuring device including the radiation measuring device and the imaging device, and a moving device capable of moving the radiation measuring device and the imaging device by remote control; and (9) a measurement value of γ-rays. The image showing at least one of measured values of thermal neutrons, two-dimensional radiation distribution of γ-rays, two-dimensional radiation distribution of thermal neutrons, burnup, and radioactivity, and an image photographed by the photographing device are folded. The present invention relates to the radiation measurement apparatus according to (8), which includes a visualization device that generates overlapping images.

  In the present specification, “the part other than the γ-ray collimator of the radiation detector” means an outer peripheral area of the radiation detector excluding the area of the radiation detector facing the opening of the γ-ray collimator, The “parts other than the plurality of γ-ray collimators” of the radiation detector of “excluding the region of the radiation detector that faces the opening of the γ-ray collimator connected to the radiation detector in each of the plurality of radiation detectors” It means the outer peripheral area of the radiation detector.

  The present invention can provide a radiation measurement apparatus that is compact and capable of accurately specifying the position of a measurement object.

It is the schematic which shows the structure of the 1st Embodiment of this invention. It is the schematic which shows the structure of the radiation detector of FIG. It is the schematic which shows an example of an energy spectrum. It is the schematic which shows the pulse waveform of a gamma ray and a neutron. It is the schematic which shows the structure of the radiation detector in the 2nd Embodiment of this invention. It is the schematic which shows the structure of the 3rd Embodiment of this invention. It is the schematic which shows the structure of the 4th Embodiment of this invention. It is the schematic which shows the structure of the 5th Embodiment of this invention. It is the schematic which shows the structure of the 6th Embodiment of this invention. It is the schematic which shows the structure of the 7th Embodiment of this invention. It is the schematic which shows the structure of the 8th Embodiment of this invention. It is the schematic which shows the structure of the 9th Embodiment of this invention.

  The radiation measurement apparatus of the present invention is a radiation measurement apparatus capable of measuring the position of a measurement object such as spent nuclear fuel containing a radioactive substance, and has a substantially cylindrical shape that narrows incident γ rays and allows neutron incidence. A γ-ray collimator having a cylindrical body, a radiation detector connected to the γ-ray collimator, having a neutron converter sensitive to thermal neutrons and measuring energy imparted by γ-rays and thermal neutrons, and the radiation detection Other than the γ-ray collimator, the γ-ray shield that shields the incidence of γ-rays other than the γ-ray through the γ-ray collimator, and the radiation detector other than the γ-ray collimator A neutron absorber that is provided so as to cover the site and absorbs neutrons irradiated to the radiation detector, and fast neutrons filled in the cylinder and emitted from the measurement object Characterized in that it comprises a neutron moderator to convert to thermal neutrons.

  The present invention also relates to a radiation measuring apparatus capable of measuring the position of a measurement object such as spent nuclear fuel containing a radioactive substance, which has a substantially cylindrical shape that narrows incident γ rays and allows neutrons to enter. A plurality of γ-ray collimators having a body, and the plurality of γ-ray collimators are two-dimensionally arranged, connected to each of the plurality of γ-ray collimators, having a neutron converter sensitive to thermal neutrons, and γ-rays And a plurality of radiation detectors for measuring energy imparted by thermal neutrons, and a plurality of the radiation detectors provided so as to cover portions other than the plurality of γ-ray collimators, and through each of the plurality of γ-ray collimators A γ-ray shield that shields the incidence of γ-rays other than γ-rays, and a portion other than the plurality of γ-ray collimators of the plurality of radiation detectors, A neutron absorber that absorbs neutrons irradiated to the ejector, and a neutron moderator that fills the inside of the cylinder and converts fast neutrons emitted from the measurement object into thermal neutrons. Includes the featured radiation measurement device.

  The “measurement object” in the present invention is uranium and / or plutonium. These produce fission products (for example, minor actinides such as Am-241 and Cm-244, Cs-137, Eu-154, Ce-144, Sr-90, etc.) by fission, and the process in which these fission products decay. Radiates radiation such as γ rays, neutrons, X rays, β rays and α rays.

  The radiation measured by the radiation measuring apparatus of the present invention includes γ rays emitted from Eu-154 as γ rays and neutrons generated by spontaneous fission of Cm-244 as neutrons from the viewpoint of specifying nuclear fuel materials. And neutrons produced by the (α, n) reaction are preferred, but are not necessarily limited to these radiations.

  Hereinafter, the first to ninth embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described in the drawings.

[First Embodiment]
FIG. 1 is a schematic view showing the configuration of the first embodiment of the present invention. The radiation measurement apparatus 1 generally includes a γ-ray collimator 111, a radiation detector 210, a γ-ray shield 311, a neutron absorber 312, a neutron moderator 411, a signal processing device 611, and a display device. 711, a distance meter 811 and a distance calculation device 812.

  The γ-ray collimator 111 is provided in order to limit the radiation incident on the radiation detector 210 to the radiation w1 from the measurement object b. The γ-ray collimator 111 narrows the incident γ-ray (limits the incident direction of the γ-ray) and neutrons. A substantially cylindrical tube body 112 (for example, a tapered tube body 112 shown in FIG. 1) that allows incidence is provided.

  The radiation detector 210 is connected to the γ-ray collimator 111, has a neutron converter 212 that is sensitive to thermal neutrons, and measures energy imparted by γ-rays and thermal neutrons. Specifically, the radiation detector 210 detects incident radiation one by one, converts each detected radiation into an electric pulse signal, and outputs it. As shown in FIG. 2, the radiation detector 210 includes a radiation sensor 211 and a readout circuit 213.

  The radiation sensor 211 detects the energy given to the radiation sensor 211 by the incident γ rays. A neutron converter 212 is dispersed in the radiation sensor 211.

  The neutron converter 212 is sensitive to thermal neutrons and converts the energy of the incident thermal neutrons to γ rays. Examples of the material constituting the neutron converter 212 include lithium 6, boron 10, gadolinium, cadmium, and the like. Among these, lithium 6 and boron 10 exhibit (n, α) reaction, and energy associated with the nuclear reaction is imparted to the radiation sensor 211. For example, in the case of lithium 6, incident neutrons are captured, and α-ray and tritium particles are generated by this capture reaction. The total energy of these particles is 4.8 MeV. Since particles generated by the above reaction are charged particles, the use of lithium 6 and boron 10 as the neutron converter 212 makes it easy to give all the energy to the inside of the radiation sensor 211.

  On the other hand, gadolinium and cadmium show (n, γ) reactions. For example, in the case of cadmium, 558 keV γ rays are generated by the incident neutron capture reaction, and energy is imparted to the radiation sensor 211 via secondary electrons generated by the interaction with the atoms of the radiation sensor 211 by the γ rays. .

Here, as the radiation sensor 211 including the neutron converter 212 and capable of analyzing γ-ray energy, for example, a semiconductor sensor such as a CdTe semiconductor sensor or a CdZnTe semiconductor sensor; Gd ₂ SiO ₅ : Ce scintillator, Cs ₂ LiLaBr ₆ : Ce A scintillator such as a scintillator, Cs ₂ LiYCl ₆ : Ce scintillator, Cs ₂ LiLaCl ₆ : Ce scintillator, Cs ₂ LiLaBr _6-x Cl _x : Ce scintillator, Cs ₂ LiYBr ₆ : Ce scintillator, or the like can be used.

  The readout circuit 213 converts each incident radiation into an electric pulse signal and outputs it. As the readout circuit 213, one suitable for each radiation sensor 211 is used. For example, a preamplifier is used for a semiconductor detector, and a photodetector is used for a scintillator. Note that the electrical pulse signal output from the readout circuit 213 is transmitted to a signal processing device 611 described later via the signal cable 511. The area where the signal cable 511 is laid has a structure such as a maze structure so that this area becomes a collimator and no streaming effect occurs.

  In addition, in order that the said radiation measuring device 1 detects both the gamma ray and neutron from the measuring object b more reliably, it is preferable that the distance of the measuring object b and the radiation detector 210 shall be 100 mm or less. In particular, fast neutrons from the measurement object b generated at a distance of 100 mm or less reach the radiation detector 210 as neutrons (also referred to as “thermal neutrons”) decelerated by the neutron moderator 411 and heated. The thermal neutrons generated by decelerating with water around the radiation measuring apparatus 1 are mainly absorbed by the neutron absorber 312 before reaching the radiation detector 210, so that the direction of the measurement object b can be more accurately determined. Can be identified.

  The γ-ray shield 311 shields the incidence of γ-rays other than γ-rays (for example, γ-rays w2 from other than the measurement object b in FIG. 1) via a γ-ray collimator 111 described later. Specifically, the γ-ray shield 311 is provided so as to cover a portion other than the opening 112 a of the γ-ray collimator 111 on the outer periphery of the radiation detector 210. Examples of the material constituting the γ-ray shield 311 include high-density materials such as lead, tungsten, and bismuth.

  The neutron absorber 312 is provided so as to cover a portion other than the γ-ray collimator 111 of the radiation detector 210, and a portion where the γ-ray collimator 111 is provided by absorbing the neutron irradiated to the radiation detector 210. The thermal neutrons are shielded so that the thermal neutrons do not reach the radiation detector 210. In the present embodiment, the neutron absorber 312 is formed on the entire outer surface of the γ-ray shield 311.

  As a material constituting the neutron absorber 312, a compound similar to the compound included in the neutron converter 212 described above can be applied. Examples of the material include boron carbide, gadolinium oxide, cadmium, and lithium fluoride.

  The neutron moderator 411 decelerates fast neutrons emitted from the measurement object b and converts them into thermal neutrons. The neutron moderator 411 is filled in the cylindrical body 112 of the γ-ray collimator 111. The thickness of the neutron moderator 411 in the axial direction of the cylinder 112 is preferably 10 mm to 100 mm, more preferably 30 mm to 70 mm, and even more preferably 40 mm to 60 mm from the viewpoint of improving the detection efficiency of thermal neutrons. The material constituting the neutron moderator 411 is not particularly limited as long as the above effect is obtained, but polyethylene and polypropylene can be suitably used.

  The signal processing device 611 is connected to the signal cable 511 described above, measures the pulse peak value, pulse integral value, and pulse waveform of the converted electric pulse signal for each of the incident radiation, and uses these to measure the radiation sensor 211. Identify the applied energy and line type.

  Specifically, the signal processing device 611 converts an input analog signal (electric pulse signal) into a digital signal using an analog circuit or an analog-digital converter, and uses a programmable array or the like using an FPGA or an ASIC. A pulse peak value, a pulse integral value, and a pulse waveform are obtained from the digital signal. As the analog-digital converter, for example, an analog-digital converter having a resolution of 10 bits or more with a sampling period of 1 MS / s or more can be adopted according to the response speed of the radiation sensor.

Here, an example of nuclide analysis performed using the signal processing device 611 is shown. In this example, the applied energy to the radiation detector 210 is derived from the pulse peak value measured by the radiation sensor 211 having the Cs ₂ LiLaBr ₆ : Ce scintillator, and the energy spectrum plotted against this applied energy is obtained. . FIG. 3 is a schematic diagram illustrating an example of an energy spectrum. In this figure, peak p2 due to 1274 keV γ rays radiated from Eu-154, peak p1 due to 662 keV γ rays radiated from Cs-137, and peak p3 due to neutrons produced by Cm-244 and (α, n) reactions. Has been detected. As described above, by appropriately selecting a radiation sensor, not only nuclide analysis for γ-ray radiation but also nuclide analysis caused by neutron radiation can be performed simultaneously in one measurement system.

When performing the above nuclide analysis, it is also preferable to combine line type discrimination using a pulse waveform. When a Cs ₂ LiLaBr ₆ : Ce scintillator is used for the radiation sensor 211, the waveform of the detected γ-ray is different from the waveform caused by neutrons. That is, as shown in FIG. 4, the waveform c2 of γ-rays and the waveform c1 caused by neutrons have different emission decay time constants, so that the three-axis is obtained by using the pulse peak value and the information on the time constant of the pulse waveform. By discriminating the response with γ, the discrimination between γ-rays and neutrons can be further enhanced.

  The display device 711 displays information such as the nuclide and radioactivity information of the measurement object b detected by the radiation detector 210. As the display device 711, for example, a display monitor having a liquid screen capable of displaying a graph or a numerical value can be employed.

  The radiation measuring apparatus 1 includes a distance meter 811 that can measure the distance between the measurement object b and the radiation detector 210, and measures radiation based on the distance measured by the distance meter 811. The distance meter 811 is not particularly limited, and a known one can be used. A distance calculation device 812 is connected to the distance meter 811, and the distance calculation device 812 calculates the distance between the measurement target part b and the radiation measurement device 1 using the measurement value measured by the distance meter 811. Thus, since the radiation measuring apparatus 1 includes the distance meter 811, for example, it can be referred to when adjusting the distance between the measurement object b and the radiation detector 210 as described later, and the efficiency Thermal neutrons can be detected well.

  Thus, the radiation measuring apparatus 1 can detect γ-rays and neutrons radiated from the measurement target b with the single radiation detector 210 because of the above configuration. As a result, the accuracy of the installation of the γ-ray detector and the neutron detector (identity of the installation positions of both detectors) and the accuracy of the measurement range of the γ-ray and neutron (identity of the part to be measured) are improved. Thus, the position of the object to be measured can be accurately specified.

[Second Embodiment]
FIG. 5 is a schematic diagram showing a configuration of a radiation detector according to the second embodiment of the present invention. The radiation measuring apparatus 2 generally includes a γ-ray collimator 111, a radiation detector 220, a γ-ray shield 311, a neutron absorber 312, a neutron moderator 411, a signal processing device 611, and a display device. 711, a distance meter 811 and a distance calculation device 812. The radiation measuring apparatus 2 is different from the first embodiment in the radiation detector 220. In addition, since structures other than the radiation detector 220 in this embodiment are the same as the structure of 1st Embodiment, the same code | symbol is attached | subjected to the same part and the detailed description is abbreviate | omitted.

    The radiation detector 220 is connected to the γ-ray collimator 111, has a neutron converter 222 that is sensitive to thermal neutrons, and measures energy imparted by γ-rays and thermal neutrons. As shown in FIG. 5, the radiation detector 220 is roughly configured by a radiation sensor 221, a neutron converter 222, a readout circuit 213, and a signal cable 511. Since the readout circuit 213 and the signal cable 511 are the same as those in the first embodiment, those of the first embodiment are used and detailed description thereof is omitted.

  The radiation sensor 221 detects energy given to the radiation sensor 221 by incident radiation. The radiation sensor 221 includes a sensor body 221a that detects the energy and a neutron converter 222 that covers the surface of the sensor body 221a.

The sensor main body 221a of this embodiment does not contain a neutron converter. For this reason, the sensor main body 221a includes a semiconductor sensor such as the CdTe semiconductor sensor and CdZnTe semiconductor sensor exemplified in the first embodiment; Gd ₂ SiO ₅ : Ce scintillator, Cs ₂ LiLaBr ₆ : Ce scintillator, Cs ₂ LiYCl ₆ : Ce scintillator, Cs ₂ LiLaCl ₆ : Ce scintillator, Cs ₂ LiLaBr _6-x Cl _x : Ce scintillator, Cs ₂ LiYBr ₆ : In addition to scintillators such as Ce scintillator, NaI (Tl) scintillator, GSO scintillator, BGO scintillator, BGO scintillator ₃ (Ce) scintillators, LYSO (Ce) scintillators, GAGG (Ce) scintillators, SrI (Eu) scintillators and the like can be employed.

  The neutron converter 222 is formed by, for example, coating or vapor deposition. Examples of the material constituting the neutron converter 222 include the same materials as those described above in the first embodiment.

  Thus, the radiation measuring apparatus 2 is compact and can accurately specify the position of the measurement object. Moreover, since the radiation measuring apparatus 2 has the above-described configuration, a wider range of semiconductor sensors and scintillators can be employed as compared with the first embodiment because the sensor main body 221a does not contain a neutron converter. .

[Third Embodiment]
FIG. 6 is a schematic diagram showing the configuration of the third exemplary embodiment of the present invention. The radiation measuring apparatus 3 generally includes a γ-ray collimator 111, a radiation detector 210, a γ-ray shield 311, a neutron absorbing material 312, a neutron moderator 431, a signal processing device 611, and a display device. 711, a distance meter 811 and a distance calculation device 812. The radiation measuring apparatus 3 is different from the first embodiment in the neutron moderator 431. In addition, since structures other than the neutron moderator 431 in this embodiment are the same as the structure of 1st Embodiment, the same code | symbol is attached | subjected to the same part and the detailed description is abbreviate | omitted.

  The neutron moderator 431 of this embodiment is covered with a neutron absorber 332. As a material constituting the neutron moderator 431, for example, the same materials as those described above for the neutron moderator 411 can be adopted. As a material constituting the neutron absorber 332, for example, the same materials as those described above for the neutron absorber 312 can be adopted. The neutron absorber 332 can be formed on the surface of the neutron moderator 431 by, for example, coating or vapor deposition.

  Thus, the radiation measuring apparatus 3 can block the thermal neutrons incident from the outside and can detect the fast neutrons radiated from the measurement object b more reliably because of the above configuration. . This is because thermal neutrons (for example, thermal neutrons generated by decelerating by surrounding water) incident from the outside via the γ-ray collimator 111 are absorbed by the neutron absorber 332, so that the radiation detector 210 receives the thermal neutrons. This is because only the fast neutrons that are removed before reaching and as a result are directly incident from the measurement object b are detected by the radiation detector 210.

[Fourth Embodiment]
FIG. 7 is a schematic diagram showing the configuration of the fourth exemplary embodiment of the present invention. The radiation measuring apparatus 4 generally includes a γ-ray collimator 111, a radiation detector 210, a γ-ray shield 311, a neutron absorber 312, a neutron moderator 411, a signal processing device 611, and a distance meter. 811, a distance calculation device 812, a shutter 941, a shutter control device 944, a signal extraction device 945, and a display device 741. The radiation measurement apparatus 4 is different from the first embodiment in that the radiation measurement apparatus 4 includes a shutter 941, a shutter control device 944, a signal extraction device 945, and a display device 741. Note that the components other than the shutter 941, shutter control device 944, signal extraction device 945, and display device 741 in the present embodiment are the same as those in the first embodiment, and thus the same parts are denoted by the same reference numerals. Detailed description thereof is omitted.

  The shutter 941 can open and close the incidence of γ rays and neutrons to the γ ray collimator 111. In this embodiment, the shutter 941 includes a movable γ-ray shutter mechanism 942 and a neutron shutter 943.

  The movable γ-ray shutter mechanism 942 is controlled using a shutter control device 944 described later, and controls the dose of γ-rays incident on the γ-ray collimator 111. As shown in FIG. 7, the movable γ-ray shutter mechanism 942 is provided so as to cover the opening 112a of the γ-ray collimator 111 so that the movable γ-ray shutter mechanism 942 can be opened and closed. Is shielded from the incidence of γ-rays on the γ-ray collimator 111, and allows the incidence of γ-rays on the γ-ray collimator 111 when “open”. As a material for shielding γ rays in the movable γ-ray shutter mechanism 942, for example, a high-density material such as lead, tungsten, or bismuth is employed.

  The neutron shutter 943 controls the dose of neutrons incident on the γ-ray collimator 111. In this embodiment, the neutron shutter 943 is provided on the outer surface of the movable γ-ray shutter mechanism 942 described above, and the opening 112a of the γ-ray collimator 111 is opened in conjunction with the opening and closing of the movable γ-ray shutter mechanism 942. Open and close. Thereby, when the neutron shutter 943 is “closed”, the incidence of neutrons to the γ-ray collimator 111 is shielded, and when it is “open”, the incidence of neutrons to the γ-ray collimator 111 is allowed.

  The shutter control device 944 controls the opening / closing operation of the movable γ-ray shutter mechanism 942 and the neutron shutter 943. The signal extraction device 945 calculates the difference between the measured value of γ-rays and the measured value derived from neutrons when the movable γ-ray shutter mechanism 942 and the neutron shutter 943 are opened and closed. The display device 741 displays information on the difference between the measurement values calculated by the signal extraction device 945 and the like.

  As described above, since the radiation measuring apparatus 4 includes the shutter 941, γ rays and neutrons incident on the radiation detector 210 from other than the measurement target b can be measured as a background, and this is excluded. Thus, the radiation from the measurement object b can be detected more accurately and reliably.

[Fifth Embodiment]
FIG. 8 is a schematic diagram showing the configuration of the fifth exemplary embodiment of the present invention. The radiation measuring apparatus 5 is roughly composed of a plurality of γ-ray collimators 111, a plurality of radiation detectors 210, a γ-ray shield 351, a neutron absorber 352, a neutron moderator 411, and a plurality of signal processing devices. 951, a two-dimensional radiation distribution analyzer 952, a display device 751, a distance meter 811, and a distance calculator 812. The radiation measurement apparatus 5 is different from the first embodiment in that the radiation measurement apparatus 5 includes a γ-ray shield 351, a neutron absorber 352, a multiple signal processing device 951, a two-dimensional radiation distribution analysis device 952, and a display device 751. Yes. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In FIG. 8, the distance meter 811 and the distance calculation device 812 are omitted.

  The radiation measurement apparatus 5 includes a plurality of γ-ray collimators 111, and the plurality of γ-ray collimators 111 are two-dimensionally arranged. Each of the plurality of γ-ray collimators 111 is connected to a radiation detector 210 that has a neutron converter 212 sensitive to thermal neutrons and measures energy imparted by γ-rays and thermal neutrons. The cylindrical body 112 of the γ-ray collimator 111 is filled with a neutron moderator 411 and converts fast neutrons emitted from the measurement object b into thermal neutrons.

  The γ-ray shield 351 is provided so as to cover a portion other than the plurality of γ-ray collimators 111 of the plurality of radiation detectors 210, and receives incidence of γ-rays other than γ-rays through each of the plurality of γ-ray collimators 111. Shield. The neutron absorber 352 is provided so as to cover portions other than the plurality of γ-ray collimators 111 of the plurality of radiation detectors 210 and absorbs neutrons irradiated to the plurality of radiation detectors 210. In this embodiment, the γ-ray shield 351 collectively covers the plurality of radiation detectors 210 and the neutron absorber 352 is formed on the entire outer surface of the γ-ray shield 351.

  The multiple signal processing device 951 is connected to the radiation detector 210 via the signal cable 112 and measures the pulse peak value, pulse integral value and pulse waveform of the electric pulse signal converted for each of the incident radiation, and these are measured. The energy and line type applied to the radiation sensor 211 are specified. The two-dimensional radiation distribution analyzer 952 receives the signal from the multiple signal processor 951 and constructs the two-dimensional distribution data of the measurement object b from the energy and the line type obtained for each radiation detector 210. The display device 751 displays an image of the two-dimensional distribution data and the like of the measurement object b obtained using the two-dimensional radiation distribution analyzer 952.

  Thus, the radiation measuring apparatus 5 can measure the two-dimensional distribution data of the measurement object b and can grasp the measurement object b two-dimensionally because of the above configuration.

[Sixth Embodiment]
FIG. 9 is a schematic diagram showing the configuration of the sixth exemplary embodiment of the present invention. The radiation measuring apparatus 6 generally includes a γ-ray collimator 111, a radiation detector 210, a γ-ray shield 311, a neutron absorber 312, a neutron moderator 411, a signal processing device 611, a distance meter. 811, a distance calculation device 812, a detection ratio calculation device 961, a burnup database 962, a burnup calculation device 963, and a display device 761. The radiation measuring apparatus 6 is different from the first embodiment in that the radiation measuring apparatus 6 includes a detection ratio calculation device 961, a burnup database 962, a burnup calculation device 963, and a display device 761. In addition, since structures other than the detection ratio calculation device 961, the burnup database 962, the burnup calculation device 963, and the display device 761 in the present embodiment are the same as those in the first embodiment, the same reference numerals denote the same parts. The detailed description is omitted.

  The detection ratio calculation device 961 calculates the ratio (detection ratio) between the count value of γ rays emitted from Eu-154 detected by the radiation detector 210 and obtained from the signal processing device 611 and the count value derived from thermal neutrons. calculate. The burnup database 962 stores correlation data between the burnup of the nuclear fuel material derived in advance and the detection ratio.

  The burnup calculation device 963 calculates the burnup from the calculated detection ratio. Specifically, the burnup calculating device 963 calculates the burnup corresponding to the detection ratio obtained by the detection ratio calculating device 961 using the correlation data stored in the burnup database 962.

  Here, the burnup can be calculated using, for example, a known calculation formula represented by the following formula (1).

In the above formula (1), B.I. U. Is the burnup [GWd / t], g (A _Eu-154 / A _neutral ) is the radioactivity ratio-burnup conversion equation, A _Eu− with the radioactivity ratio of γ-rays and thermal neutrons of Eu-154 as a parameter. ₁₅₄ is the radioactivity [Bq] of γ rays from Eu-154, n _Eu-154 is the measurement count rate [1 / s], ε _Eu-154 is the detection efficiency of γ rays from _Eu-154 , p _Eu-154 Is the emissivity (1 / Bq), _Aneutron is the neutron source activity [Bq], _εneutron is the neutron detection efficiency, _pneutron is the neutron emission rate [1 / Bq], _nneutron is the measurement count rate [1 / s ] Respectively.

  The display device 761 displays an image of information related to the burnup calculated by the burnup calculation device 963.

  Thus, the said radiation measuring device 6 can calculate a burnup by being the said structure. As a result, the radiation measuring apparatus 6 can estimate the use period of the nuclear fuel in the nuclear reactor and the radioactivity from the measurement object b using the obtained burnup.

[Seventh Embodiment]
FIG. 10 is a schematic diagram showing the configuration of the seventh exemplary embodiment of the present invention. The radiation measuring device 7 is roughly composed of a γ-ray collimator 111, a radiation detector 210, a γ-ray shield 311, a neutron absorber 312, a neutron moderator 411, a signal processing device 611, a distance meter. 811, a distance calculation device 812, a detection ratio calculation device 961, a burnup database 962, a burnup calculation device 963, a detection efficiency database 971, a radioactivity calculation device 972, and a display device 771. Yes. The radiation measuring device 7 is different from the sixth embodiment in that the radiation measuring device 7 includes a detection efficiency database 971, a radioactivity calculation device 972, and a display device 771. In addition, since structures other than the detection efficiency database 971, the radioactivity calculation apparatus 972, and the display apparatus 771 in this embodiment are the same as the structure of 6th Embodiment, the same code | symbol is attached | subjected to the same part and the detail The detailed explanation is omitted.

  The detection efficiency database 971 stores data on the detection efficiency of γ rays and thermal neutrons in advance. Here, the detection efficiencies correspond to the configurations of the radiation measurement apparatus 7 including the radiation detector 210, the γ-ray shield 311, the γ-ray collimator 111, the neutron moderator 411, and the neutron absorber 312, respectively. Γ-ray detection efficiency from 154 and thermal neutron detection efficiency. These detection efficiencies are derived in advance by experimental methods or analytical methods. Each of the above methods can employ a known technique.

  The radioactivity calculator 972 includes a distance measured by the distance meter 811, a count value of γ rays and a count value derived from thermal neutrons measured by the radiation detector 210, and γ rays and thermal neutrons stored in the detection efficiency database 971. The radioactivity of the measurement object b is calculated using the detection efficiency data and the burnup calculated by the burnup calculation device 963. The radioactivity calculation method by the radioactivity calculation device 972 is not particularly limited, and can be calculated using a known technique. The display device 771 displays an image of information related to the radioactivity calculated by the radioactivity calculation device 972.

  Thus, the radioactivity of the measuring object b can be grasped | ascertained because the said radiation measuring device 7 is the said structure.

[Eighth Embodiment]
FIG. 11 is a schematic view showing the configuration of the eighth embodiment of the present invention. The radiation measuring apparatus 8 is roughly composed of a γ-ray collimator 111, a radiation detector 210, a γ-ray shield 311, a neutron absorbing material 312, a neutron moderator 411, a signal processing device 611, a display device 711, a distance meter 811, And a radiation measuring device having a distance calculating device 812, an imaging device 981, a moving device 984, and a position calculating device 987. The radiation measuring device 8 is different from the first embodiment in that it includes an imaging device 981 and a moving device 984. In addition, since structures other than the imaging device 981 and the moving device 984 in the present embodiment are the same as those in the first embodiment, the same portions are denoted by the same reference numerals and detailed description thereof is omitted.

  The imaging device 981 captures surrounding images. The photographing device 981 includes an image sensor 982 and an image calculation device 983. The image sensor 982 images the surroundings of the radiation measuring apparatus 8 and outputs an image signal. Here, the image captured by the image sensor 982 is not limited to visible light, and examples thereof include electromagnetic waves other than visible light, and sound waves such as ultrasonic waves. The image arithmetic unit 983 inputs the image signal from the image sensor 982 and visualizes it.

  The moving device 984 can mount the radiation measuring device 1 and the imaging device 984, and can move the radiation measuring device 1 and the imaging device 984 by remote control. The mobile device 984 includes a remote access device 985 and an access device control device 986. Specifically, the remote access device 985 includes the above-described γ-ray collimator 111, radiation detector 210, γ-ray shield 311, neutron absorber 312, neutron moderator 411, distance meter 811, and imaging device 981. These can be moved freely. The moving mechanism used for the remote access device 985 is not particularly limited, and for example, means for driving an endless track with a rotating electrical machine can be employed. The access device control device 986 controls the traveling direction and traveling speed of the remote access device 985.

  The position calculation device 987 derives the position of the radiation measurement device 8 using the video obtained by the image calculation device 983.

  Thus, when the radiation measurement apparatus 8 has the above-described configuration, the measurement range of the measurement object b can be expanded in a radiation environment, for example, a place where a structure is complicated and a narrow portion.

[Ninth Embodiment]
FIG. 12 is a schematic diagram showing the configuration of the ninth embodiment of the present invention. The radiation measuring apparatus 9 generally includes a γ-ray collimator 111, a radiation detector 210, a γ-ray shield 311, a neutron absorber 312, a neutron moderator 411, a signal processing device 611, and a distance meter. 811, a distance calculation device 812, a photographing device 981, a moving device 984, a position calculation device 987, a visualization device 991, and a display device 791. The radiation measuring apparatus 9 is different from the eighth embodiment in that it includes a visualization device 991 and a display device 791. In addition, since structures other than the visualization apparatus 991 and the display apparatus 791 in this embodiment are the same as the structure of 8th Embodiment, the same code | symbol is attached | subjected to the same part and the detailed description is abbreviate | omitted.

  The visualization device 991 includes an image showing at least one of a measured value of γ-rays, a measured value of thermal neutrons, a two-dimensional radiation distribution of γ-rays, a two-dimensional radiation distribution of thermal neutrons, a burnup, and a radioactivity, An image obtained by overlapping the image photographed by the photographing device 981 is generated. The display device 791 displays the image generated by the visualization device 991 as an image.

  Thus, since the said radiation measuring device 9 is the said structure, various measurement results, such as a gamma ray, can be easily matched with the visible real image, As a result, work, such as a radiation measurement, can be performed exactly. Can do.

  In addition, this invention is not limited to the structure of embodiment mentioned above, is shown by the claim, and intends that all the changes within the meaning and range equivalent to a claim are included. Is done.

  For example, in the above-described embodiment, the radiation measuring device including the distance meter 811 and the distance calculating device 812 has been described. However, the above-described distance is used as long as it is not necessary to measure radiation based on the distance between the measurement object and the radiation detector. It may be a radiation measurement device that does not include the total 811 and the distance calculation device 812.

  Further, in the above embodiment, the radiation measuring apparatus in which the neutron absorbers 312 and 352 are respectively formed on the outer surfaces of the γ-ray shields 311 and 351, and the neutron shutter 943 on the outer surface of the movable γ-ray shutter mechanism 942. Although the radiation measuring apparatus provided is described, the radiation measuring apparatus in which these positions are reversed (for example, a radiation measuring apparatus in which a γ-ray shield is formed on the outer surface of the neutron absorber) may be used. .

1-9 Radiation measurement apparatus b Measurement object 111, 151 γ-ray collimator 112 Tube 210, 220 Radiation detector 311, 351 γ-ray shield 312, 332, 352 Neutron absorber 411 Neutron moderator 941 Shutter 811 Distance meter 961 Detection ratio calculation device 963 Burnup calculation device 971 Detection efficiency database 972 Radioactivity calculation device 981 Imaging device 984 Moving device 991 Visualization device

Claims (9)

A radiation measurement device capable of measuring the location of a measurement object such as spent nuclear fuel containing radioactive material,
A γ-ray collimator having a substantially cylindrical cylindrical body that narrows incident γ-rays and allows neutrons to enter;
A radiation detector connected to the γ-ray collimator, having a neutron converter sensitive to thermal neutrons and measuring the energy imparted by γ-rays and thermal neutrons;
A γ-ray shield that is provided so as to cover a portion other than the γ-ray collimator of the radiation detector and shields the incidence of γ-rays other than γ-rays through the γ-ray collimator;
A neutron absorbing material that is provided so as to cover a portion other than the γ-ray collimator of the radiation detector and absorbs neutrons irradiated to the radiation detector,
A radiation measurement apparatus comprising: a neutron moderator that fills the inside of the cylindrical body and converts fast neutrons emitted from the measurement object into thermal neutrons.   The radiation measuring apparatus according to claim 1, wherein the neutron moderator is coated with a neutron absorber.   The radiation measuring apparatus according to claim 1, further comprising a shutter capable of opening and closing the incidence of γ rays and neutrons to the γ ray collimator.   The radiation measurement according to any one of claims 1 to 3, further comprising a distance meter capable of measuring a distance between the measurement object and the radiation detector, and measuring radiation based on the distance measured by the distance meter. apparatus. A radiation measurement device capable of measuring the location of a measurement object such as spent nuclear fuel containing radioactive material,
A plurality of γ-ray collimators having a substantially cylindrical body that narrows incident γ-rays and allows neutrons to enter;
These multiple γ-ray collimators are arranged two-dimensionally,
A plurality of radiation detectors connected to each of the plurality of γ-ray collimators, having a neutron converter sensitive to thermal neutrons and measuring energy imparted by γ-rays and thermal neutrons;
A γ-ray shield that is provided so as to cover a portion other than the plurality of γ-ray collimators of the plurality of radiation detectors and shields the incidence of γ-rays other than γ-rays through each of the plurality of γ-ray collimators;
A neutron absorber that is provided so as to cover a portion other than the plurality of γ-ray collimators of the plurality of radiation detectors, and that absorbs neutrons irradiated to the plurality of radiation detectors;
A radiation measurement apparatus comprising: a neutron moderator that fills the inside of the cylindrical body and converts fast neutrons emitted from the measurement object into thermal neutrons.   A detection ratio calculation device that calculates a ratio between a count value of γ rays detected by the radiation detector and a count value derived from thermal neutrons; and a burnup calculation device that calculates the burnup from the calculated ratio The radiation measurement apparatus according to claim 1, wherein the radiation measurement apparatus is a radiation measurement apparatus. A distance meter capable of measuring the distance between the object to be measured and the radiation detector;
A detection efficiency database in which data of detection efficiency of γ-rays and thermal neutrons are stored in advance;
The distance measured by the distance meter, the count value of γ rays and the count value derived from thermal neutrons measured by a radiation detector, the data of the detection efficiency of γ rays and thermal neutrons stored in the detection efficiency database, and The radiation measurement apparatus according to claim 6, further comprising a radioactivity calculation apparatus that calculates the radioactivity of the measurement object using a burnup degree. The radiation measurement apparatus according to any one of claims 1 to 7,
A photographing device for photographing surrounding images;
A radiation measuring apparatus including the radiation measuring apparatus and the imaging apparatus, and a moving device capable of moving the radiation measuring apparatus and the imaging apparatus by remote control.   An image showing at least one of a measured value of γ-rays, a measured value of thermal neutrons, a two-dimensional radiation distribution of γ-rays, a two-dimensional radiation distribution of thermal neutrons, a burnup, and a radioactivity, and a photographer The radiation measurement apparatus according to claim 8, further comprising a visualization device that generates an image obtained by overlapping the captured image.