JP2014115272A - Radioactivity measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and accurately measure the amount of radioactivity of whole radioactive waste stored in a storage container, and to increase versatility.SOLUTION: A radioactivity measuring apparatus comprises: a slide movement part for linearly moving a storage container; a radiation detection part that is disposed in a route where the slide movement part moves the storage container and in which a detector unit is disposed on at least one or more surfaces except two surfaces in a direction where the slide movement part moves the storage container; and a radioactivity amount calculation part that obtains the amount of radiation, emitted from the surfaces of the storage container, detected by the radiation detection part and that averages the amounts of radiation obtained from the respective surfaces to calculate the amount of radioactivity of whole radioactive waste. The detector unit includes a plurality of detectors, and a plurality of detection elements are arrayed in two dimensions in the detectors.

Description

  The present invention relates to a radioactivity measuring apparatus that measures the amount of radioactivity of radioactive waste stored in a storage container without destroying the storage container.

  As an apparatus for measuring the radioactivity of radioactive waste, an apparatus for measuring the radioactivity of a radioactive waste without destroying the storage container in a state where the radioactive waste is stored in the storage container is known (Patent Document). 1 and 2).

  In recent years, it has been studied to rationalize the transportation disposal cost by increasing the size of the storage container and to rationalize the mounting volume by using the storage container as a square shape. For example, the adoption of a large and square storage container is being studied as a storage container.

  As a radioactivity measuring apparatus for measuring the radioactivity of the radioactive waste stored in such a rectangular storage container, Patent Document 3 measures the radioactivity of the radioactive waste stored in a rectangular hexahedral storage container. A radioactivity measuring device, wherein the radiation detector is disposed facing the four surfaces except the two opposite surfaces of the storage container at the same distance, and the storage container is arranged in a direction perpendicular to the two surfaces of the storage container. A slide moving unit that relatively slides each of the radiation detection units, a rotation moving unit that rotates the storage container by 90 degrees with an axis perpendicular to two predetermined opposite surfaces of the four surfaces of the storage container, The radiation amount emitted from each of the six surfaces of the storage container is input from each radiation detection unit by the slide movement of the slide movement unit and the slide movement of the slide movement unit after the rotation movement of the rotation movement unit, and the radiation And radioactivity calculating unit for calculating the radioactivity of the whole radioactive wastes on average, radioactivity measuring apparatus comprising a are listed.

Japanese Patent No. 3616036 Japanese Patent No. 4576108 JP 2012-47544 A

  Here, the radiation dose can be measured with high accuracy by measuring the radiation dose on the entire surface (six surrounding surfaces) of the storage container as in the radioactivity measuring device described in Patent Document 3. Here, it is desired that the radioactivity measuring device has higher versatility.

  The present invention solves the above-mentioned problems, and provides a highly versatile radioactivity measuring apparatus that can easily and accurately measure the amount of radioactivity in the entire radioactive waste stored in a storage container. With the goal.

  In order to achieve the above-mentioned object, the radioactivity measurement apparatus of the present invention is a radioactivity measurement apparatus for measuring the radioactivity amount of radioactive waste stored in a storage container, and slide movement for linearly moving the storage container And the slide moving unit are arranged in a path for moving the storage container, and the detector unit is arranged on at least one surface excluding two surfaces in a direction in which the slide moving unit moves the storage container. The radiation amount emitted from each surface of the storage container detected by the radiation detection unit and the radiation detection unit is acquired, and the radiation amount of the acquired surface is averaged to calculate the radioactivity amount of the entire radioactive waste The detector unit has a plurality of detectors, and the detector has a plurality of detection elements arranged two-dimensionally.

  According to this radioactivity measurement apparatus, in order to measure the radioactivity amount of the radioactive waste stored in the storage container from the surface of the storage container with a detector unit in which a plurality of detectors equipped with two-dimensionally arranged detection elements are arranged, The amount of radioactivity of the whole radioactive waste stored in the storage container can be accurately measured. Moreover, according to this radioactivity measuring apparatus, it can respond to the storage balance of various storage containers and various radioactive waste, and can increase the object which can be measured. Thereby, the versatility as an apparatus can be made high.

  In the radioactivity measurement apparatus of the present invention, the detection element is a semiconductor element containing CdTe or CdZnTe.

  According to this radioactivity measurement apparatus, the apparatus can be made inexpensive by using a semiconductor element containing CdTe or CdZnTe as the detection element. Further, by using a detector in which the detection elements are two-dimensionally arranged, the radiation to be measured can be appropriately detected even if a semiconductor element containing CdTe or CdZnTe is used, and further, radiation derived from the natural world is detected. This can be suppressed.

  Further, the radioactivity measurement apparatus of the present invention includes a control unit that counts the number of pulses detected by the detection element, and changes the voltage applied to the detection element when the counted pulse count number is equal to or greater than a threshold value. It is characterized by providing.

  According to this radioactivity measurement apparatus, it is possible to suppress the occurrence of detection omission of a pulse that is a detection result signal during measurement using the detection element, and it is possible to further increase measurement accuracy.

  In the radioactivity measurement apparatus according to the present invention, the detector units are arranged on four surfaces of the radiation detection unit other than two surfaces in a direction in which the storage container is moved.

  According to this radioactivity measuring apparatus, since the measurement is performed from each surface of the storage container by the detector unit, the radioactivity amount of the entire radioactive waste stored in the storage container can be accurately measured.

  In addition, the radioactivity measurement apparatus of the present invention is characterized by having a rotation moving unit that rotates the storage container 90 degrees about an axis that is perpendicular to two predetermined opposing surfaces of the storage container.

  According to this radioactivity measuring apparatus, since measurement can be performed on the six surfaces around the storage container, the radioactivity amount of the entire radioactive waste stored in the storage container can be accurately measured.

  Further, in the radioactivity measurement apparatus according to the present invention, the radiation detection unit is linearly moved by the slide moving unit, measures the radiation dose on the four surfaces of the storage container moved to the facing position, and then the slide movement Measuring the radiation dose on the remaining two surfaces of the storage container that has been linearly moved to the rotational movement unit by the unit, rotated by the rotational movement unit, linearly moved by the slide movement unit, and moved to the facing position. The radioactivity calculation unit acquires the radiation doses emitted from the six surfaces of the storage container, and averages the acquired radiation doses on the six surfaces.

  According to this radioactivity measuring apparatus, the radioactivity amount of the entire radioactive waste is calculated by averaging the radiation dose measured from each surface of the storage container. Therefore, the radioactivity amount of the entire radioactive waste can be easily calculated. .

  In the radioactivity measurement apparatus of the present invention, the detector unit is two-dimensionally arranged on a surface facing the storage container.

  According to this radioactivity measuring apparatus, the radiation dose on the target surface of the storage container can be measured with a small number of measurements.

  In the radioactivity measurement apparatus according to the present invention, the detector unit may include the entire region of the region where the detector arranged in a two-dimensional array faces the storage container.

  According to this radioactivity measurement apparatus, the radiation dose on the target surface of the storage container can be measured at a time, so that the measurement can be performed in a short time.

  In the radioactivity measurement apparatus of the present invention, the storage container is a rectangular parallelepiped.

  According to this radioactivity measurement apparatus, the relationship between the detector unit and the storage container can be made constant, and the radioactivity amount can be measured with higher accuracy.

  In the radioactivity measurement apparatus according to the present invention, the storage container is a curved body having at least one curved surface.

  According to this radioactivity measuring apparatus, the amount of radioactivity can be measured with high accuracy even in a curved container.

  Further, the radioactivity measurement apparatus of the present invention includes the radiation detection unit, covers a range where the radiation detection unit faces the surface of the storage container, and shields the detection unit that shields radiation from the outside of the device to the radiation detection unit. It comprises a part.

  According to this radioactivity measuring apparatus, the radiation from the outside of the apparatus to the radiation detection section is shielded by the detection section shielding section, thereby preventing the radiation detection section from detecting the radiation from the outside of the apparatus. Can be detected with high accuracy.

  Further, the radioactivity measurement apparatus of the present invention includes a storage container shielding unit that covers the storage container when the radiation detection unit detects radiation and shields radiation from the outside of the apparatus to the storage container. To do.

  According to this radioactivity measurement device, radiation that reaches the storage container from the outside of the apparatus is shielded by the storage container shielding part, so that radiation that is released from outside the storage container to the outside of the storage container is detected. Therefore, the radiation emitted from the storage container to the outside can be detected with high accuracy.

  In the radioactivity measurement apparatus according to the present invention, the detector includes a terminal connected to the detection element, a substrate supporting a plurality of detection elements, and the detection element is detachable from the terminal. It is connected.

  According to this radioactivity measurement apparatus, it is possible to easily replace the detection element.

  Moreover, the radioactivity measuring apparatus of this invention is provided with the cover with which the said detector covers except the surface which faces the said storage container of the said several detection element.

  According to this radioactivity measurement apparatus, it is possible to prevent light from outside the apparatus from entering the space where the detection element is arranged.

  In the radioactivity measurement apparatus of the present invention, the detector includes a switch that is provided between the detection element and the radioactivity amount calculation unit, and that switches the detection element that measures the radiation dose. .

  According to this radioactivity measuring apparatus, it is possible to switch the detection element for measuring the radiation dose, that is, the detection element for acquiring the signal, and the radiation dose detected by each detection element can be acquired separately. Thereby, the detection result of each detection element can be grasped, and the state of each detection element can be determined with high accuracy.

  In the radioactivity measurement apparatus according to the present invention, the detector includes a plurality of the detection elements in which the detection elements are arranged in a matrix and the switches are arranged in a plurality of the same rows or the same columns, and the radioactivity amount calculation unit. The detection elements for measuring the radiation dose are switched by sequentially switching the connections of the plurality of detection elements and the radioactivity amount calculation unit in the row and the column.

  According to this radioactivity measurement apparatus, switches can be efficiently arranged, and the number of switches for the detection element can be reduced.

  According to the present invention, it is possible to easily and accurately measure the total amount of radioactivity of radioactive waste stored in different types of storage containers and radioactive waste stored in various balances in the storage containers. . Thereby, versatility can be made high.

FIG. 1 is a perspective view showing a schematic configuration of a radioactivity measuring apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken in the x direction in FIG. 3 is a cross-sectional view in the y direction in FIG. FIG. 4 is a perspective view illustrating a schematic configuration of the radiation detection unit. FIG. 5 is a block diagram illustrating a schematic configuration of the radiation detection unit. FIG. 6 is a flowchart showing an example of the operation of the radioactivity measuring apparatus according to the embodiment of the present invention. FIG. 7 is a flowchart showing an example of the operation of the radioactivity measuring apparatus according to the embodiment of the present invention. FIG. 8 is a graph showing an example of measurement results. FIG. 9A is a schematic diagram illustrating an example of a storage container storing radioactive waste. FIG. 9B is a schematic diagram illustrating an example of a storage container storing radioactive waste. FIG. 9C is a schematic diagram illustrating an example of a storage container storing radioactive waste. FIG. 10 is a schematic diagram illustrating another example of the detector. FIG. 11 is a cross-sectional view of the detector shown in FIG. FIG. 12 is a schematic diagram illustrating a relationship between detection elements and switches of the detector illustrated in FIG. FIG. 13 is a schematic diagram illustrating another example of the relationship between the detection element and the switch. FIG. 14 is a perspective view showing a schematic configuration of the detection jig. FIG. 15 is an explanatory diagram for explaining a detection operation using the detection jig. FIG. 16 is an explanatory diagram for explaining the function of the detection element. FIG. 17 is a graph showing an example of the relationship between the bias voltage of the detection element and the coefficient efficiency. FIG. 18 is a graph showing an example of the relationship between the detected pulse and time. FIG. 19 is a graph showing an example of the relationship between the detected pulse and time. FIG. 20 is a flowchart showing an example of the operation of the radioactivity measurement apparatus according to the embodiment of the present invention. FIG. 21 is a perspective view showing another example of the storage container. FIG. 22 is a perspective view showing another example of the storage container. FIG. 23 is a perspective view showing a schematic configuration of another example of the radioactivity measurement apparatus. FIG. 24 is a perspective view showing a schematic configuration of another example of the radioactivity measurement apparatus. FIG. 25 is a perspective view illustrating a schematic configuration of the radiation detection unit.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  FIG. 1 is a perspective view showing a schematic configuration of a radioactivity measuring apparatus according to the present embodiment. FIG. 2 is a cross-sectional view taken in the x direction in FIG. 3 is a cross-sectional view in the y direction in FIG. Note that the x direction, y direction, and z direction indicated by arrows in the figure are directions that intersect each other at 90 degrees, the x direction indicates the left-right direction (horizontal direction), and the y direction is the front-rear direction (horizontal direction). The z direction indicates the vertical direction (vertical direction).

  The radioactivity measuring apparatus 1 of the present embodiment measures the radioactivity amount of radioactive waste stored in the storage container 100 without destroying the storage container 100. The radioactivity measuring apparatus 1 discriminates and measures gamma rays emitted from, for example, Co-60 (cobalt 60) and Cs-137 (cesium 137) as the radioactivity, thereby measuring the radioactivity contained in the storage container 100. taking measurement. The storage container 100 has a rectangular parallelepiped shape made of iron having surfaces perpendicular to the x direction, the y direction, and the z direction. For example, the x direction × y direction × z direction is 160 [cm] × 160 [cm] × It is a regular hexahedron with a wall thickness of 1 [cm] at 160 [cm]. Further, as shown in FIGS. 2 and 3, the radioactivity measurement apparatus 1 measures the radioactivity amount of radioactive waste stored in a storage container 102 smaller than the storage container 100 without destroying the storage container 102. It is also a thing. The storage container 102 is a rectangular parallelepiped made of iron having surfaces perpendicular to the x, y, and z directions. For example, the x direction × y direction × z direction is 135 [cm] × 135 [cm] × It is 93 [cm] and forms a rectangular parallelepiped with a wall thickness of 0.2 [cm] made of iron. Hereinafter, it demonstrates as a case where the radioactivity amount of the radioactive waste accommodated in the storage container 100 is measured.

  As shown in FIGS. 1 to 3, the radioactivity measurement apparatus 1 includes a radiation detection unit 2, a slide movement unit 3, a rotation movement unit 4, a radioactivity amount calculation unit 5, a detection unit shielding unit 6, and a storage unit. The container shielding part 7, the weight measurement part 8, and the control part 10 are provided.

  FIG. 4 is a perspective view illustrating a schematic configuration of the radiation detection unit. FIG. 5 is a block diagram illustrating a schematic configuration of the radiation detection unit. Hereinafter, in addition to FIGS. 1 to 3, the radiation detection unit will be described with reference to FIGS. 4 and 5. The radiation detection unit 2 measures γ rays without destroying the storage container 100. The radiation detection unit 2 includes four detector units 20. The four detector units 20 are arranged at positions facing the four surfaces in the x direction and the z direction, respectively, excluding two opposite surfaces (two surfaces opposite in the y direction) of the storage container 100. That is, the four detector units 20 are arranged opposite to each other in the x direction in the direction in which the xy plane is the measurement surface, and opposite in the z direction in the direction where the yz plane is the measurement surface. Two detector units 20 are arranged. The radioactivity measurement apparatus 1 according to the present embodiment includes a frame 1a for securing a region where the detector unit 20 is disposed on the bottom side (the surface on the bottom side in the z direction) of the storage container 100. Further, the four detector units 20 of the present embodiment have basically the same shape except that the arrangement position and the arrangement direction are different. In addition, the detector unit 20 is disposed at the same distance (for example, 10 [cm]) from the facing surface of the storage container 100. Here, the detector unit 20 is arranged asymmetrically and more than a certain distance away from the storage container 102 smaller than the storage container 100.

  In the detector unit 20, a plurality of detectors 22 are two-dimensionally arranged. In the detector unit 20 of the present embodiment, nine detectors 22 are arranged in a matrix of 3 rows and 3 columns. The detector unit 20 performs measurement with each of the two-dimensionally arranged detectors 22 so as to divide the facing surface of the storage container 100 into the number of detectors 22 and detect the radiation with each of the detectors 22. Do.

  The detector 22 has basically the same shape except for the arrangement position. One detector 22 has a plurality of detection elements 24 arranged two-dimensionally. In the detector 22 of the present embodiment, nine detection elements 24 are arranged in a matrix of 3 rows and 3 columns. The detector 22 performs measurement with each of the two-dimensionally arranged detection elements 24, so that the facing surface of the storage container 100 is divided for each detector 22, and a region assigned to the detector 22 is further detected. The detection element 24 is divided into 24 pieces, and each detection element 24 detects radiation.

  Next, the apparatus configuration of the radiation detection unit 2 and the flow of detection signals (detection values) will be described in more detail with reference to FIG. As described above, the radiation detection unit 2 includes four detector units 20 arranged one by one on each of the four surfaces of the storage container 100 other than the traveling direction. One detector unit 20 includes nine detectors 22. One detector 22 includes nine detection elements 24.

  First, one detector 22 includes nine detection elements 24, a power supply 30, an adder 32 that adds up signals, and a preamplifier 34. Further, the detection element 24 and the addition unit 32 are connected to the ground. The power supply 30 supplies power to the nine detection elements 24. The detection element 24 detects the radiation at the position facing the storage container 100 and outputs a detected signal to the addition unit 32. The adder 32 sums up the signals output from the nine detection elements 24 and outputs the sum to the preamplifier 34. The preamplifier 34 amplifies the signal output from the adder 32 and outputs it to the outside.

  The detector unit 20 includes nine detectors 22, an amplifier 36, a discriminator 38, and an MCA 40. In the detector unit 20, signals detected by the nine detectors 22, specifically, signals amplified by the preamplifier 34 are input to the amplifier 36. The amplifier 36 amplifies the input signal and inputs it to the discriminator 38. The discriminator 38 is a frequency discriminator, which separates the signal amplified by the amplifier 36 into pulses and separates it into noise and radiation. The discriminator 38 inputs the separated radiation component signal to the MCA 40. An MCA (Multi Channel Analyzer) 40 extracts a spectrum (relation between each energy (voltage) and a count value) of an input signal (detection result). This extracted spectrum is a spectrum of radiation detected over the entire surface of the storage container 100 that the detector unit 20 faces. The MCA 40 sends the extracted energy spectrum information to the radioactivity calculation unit 5.

  The radiation detector 2 performs the above-described detection with each of the four detectors 22, so that the radioactivity of the entire surface of each of the four surfaces of the storage container 100 facing the detector unit 20 is reduced. Detect the spectrum. In the radiation detection unit 2, one detector unit 20 includes a plurality (nine) of detectors 22, and one detector 22 includes a plurality of (nine) detection elements 24. As a result, the detector unit 20 measures radiation output from the target surface of the storage container 100 using a large number (81) of the detection elements 24 arranged in divided regions. As shown in FIG. 5, the radiation detection unit 2 employs a method in which the detection element 24 is inserted into a parallel connection substrate, the detector unit 20 is unitized by a plurality of detectors 22, and the detector 22 is converted into a plurality of detection elements 24. Maintenance can be improved by unitizing with. In the present embodiment, the number of detectors 22 constituting the detector unit 20 and the number of detection elements 24 constituting the detector 22 are not limited to this. The detector unit 20 includes a plurality of detection elements 24. It is only necessary to provide a plurality of detectors 22. For example, the detector unit 20 may arrange the detectors 22 in 4 rows and 4 columns.

  The detector 22 includes a cover 23 that covers the plurality of detection elements 24. The cover 23 covers other than the surface of the detection element 24 that faces the storage container 100. By providing the cover 23 that covers the detection element 24, the detector 22 can suppress light from the outside of the apparatus from entering the detection element 24. Thereby, the detection by the detection element 24 can be performed with higher accuracy.

  The slide moving unit 3 relatively slides and moves the storage container 100 and the radiation detection unit 2 in the y direction, which is a direction orthogonal to two opposite surfaces (two surfaces opposite to each other in the y direction) of the storage container 100 described above. It is something to be made. The slide moving unit 3 in the present embodiment slides the storage container 100 in the y direction while keeping the radiation detecting unit 2 stationary. For example, the slide moving unit 3 includes a pair of rails 3a extending in the y direction so as to support the bottom surface of the storage container 100 as shown in FIG. Moving means for moving the storage container 100 along the present direction. The slide moving unit 3 can move the storage container 100 in the y direction before and after the radiation detecting unit 2. That is, the slide moving unit 3 can be moved from the position of the storage container 100 to the position of the storage container 100a.

  The rotational movement unit 4 has a vertical axis center perpendicular to the two opposite surfaces (two surfaces opposite to each other in the z direction) of the four surfaces of the storage container 100 that the radiation detection unit 2 faces. Is rotated 90 degrees. The rotational movement part 4 in this Embodiment is provided in the edge part (end part of the rail 3a) of the slide movement of the storage container 100 by the slide movement part 3, and is a rotary table rotationally driven by the axial center along az direction. 4a.

  The radioactivity amount calculation unit 5 radiates γ rays emitted from the six surfaces of the storage container 100 by the slide movement of the slide movement unit 3 and the slide movement of the slide movement unit 3 after the rotation movement of the rotation movement unit 4. Input from the detector 2. Then, the radioactivity calculation unit 5 calculates the total radioactivity of the radioactive waste by averaging the input γ dose and evaluating the amount derived from Co-60 and Cs-137 among the γ rays. . In addition, the calculation process which the radioactivity amount calculation part 5 performs is mentioned later.

  The detection unit shielding unit 6 includes the radiation detection unit 2 and covers a range where the radiation detection unit 2 faces the surface of the storage container 100. The detection unit shielding unit 6 is configured as a rectangular box body in which only the side where the radiation detection unit 2 faces the storage container 100 is opened by a lead plate made of lead having a thickness of 3 cm, for example, The radiation detection unit 2 is disposed inside. With this configuration, the detection unit shielding unit 6 shields radiation from the outside of the apparatus to the radiation detection unit 2.

  The storage container shielding unit 7 covers the storage container 100 when the radiation detection unit 2 detects radiation. The storage container shielding unit 7 is a range of sliding movement of the storage container 100 by the slide moving unit 3 when detecting radiation by the radiation detection unit 2, for example, by an iron plate having a thickness of 4 [cm] made of iron. The container 100 is configured as a rectangular box that covers four surfaces of the storage container 100 in the x direction and the z direction with a predetermined distance (for example, 10 [cm]). With this configuration, the storage container shielding unit 7 shields radiation from the outside of the apparatus to the storage container 100 when the radiation detection unit 2 detects radiation. Moreover, the storage container shielding part 7 is a structure which does not cover the storage container 100 in the site | part which provided the detection part shielding part 6 mentioned above so that the detection of the radiation by the radiation detection part 2 may not be prevented. Further, when the storage container 100 is carried into the apparatus from the end in the slide movement direction (y direction) of the slide movement unit 3 that is not on the rotational movement unit 4 side, both sides in the y direction are opened. It is configured as a cylinder. When the storage container shielding unit 7 carries the storage container 100 into the apparatus from the rotational movement unit 4 side, the end of the slide movement unit 3 that is not on the rotational movement unit 4 side in the slide movement direction (y direction) is It may be occluded.

  The weight measuring unit 8 is installed side by side with the rotary moving unit 4 and measures the weight of the storage container 100 supported by the rotary table 4a. The weight measuring unit 8 sends the measured weight to the radioactivity calculation unit 5.

  The control unit 10 is an arithmetic device including a CPU (Central Processing Unit), a storage device, and the like, and the operations of the radiation detection unit 2, the slide movement unit 3, the rotation movement unit 4, the radioactivity amount calculation unit 5, and the weight measurement unit 8. To control. The radioactivity measurement apparatus 1 may share the control unit 10 and the radioactivity amount calculation unit 5 as one arithmetic device, that is, hardware. That is, each process may be processed in parallel by one CPU.

  The calculation operation of the radioactivity amount by the radioactivity measurement apparatus 1 of the present embodiment will be described. FIG. 6 is a flowchart showing an example of the operation of the radioactivity measuring apparatus according to the embodiment of the present invention. Note that the processing illustrated in FIG. 6 can be realized by the control unit 10 controlling the operation of each unit.

  The control unit 10 detects that the storage container 100 has been placed on the rotational movement unit 4 (step S12). When the control unit 10 detects a load with the weight measuring unit 8 provided in the rotational movement unit 4 or when an operation indicating that the storage container 100 is input by the operator is detected, the rotational movement unit 4 Detects that it was placed on.

  When the control unit 10 detects that the storage container 100 is placed on the rotational movement unit 4, the control unit 10 measures the weight of the storage container 100 (step S <b> 14), and then the slide movement unit 3 moves the storage container 100 to the radiation detection unit 2. (Step S16). That is, the storage container 100 is moved by the slide moving unit 3 to a position where the radiation detection unit 2 can measure the storage container 100 (a position where each detector unit 20 of the radiation detection unit 2 and the storage container 100 face each other).

  After moving the storage container 100 to the radiation detection unit 2, the control unit 10 measures the radiation on the four surfaces of the storage container 100 (step S18). That is, the radiation of the four surfaces of the storage container 100 is measured by measuring the radiation of the surfaces of the storage container 100 facing each detector unit 20.

  When measuring the radiation of the four surfaces of the storage container 100, the control unit 10 moves the storage container 100 to the rotational movement unit 4 by the slide movement unit 3 (step S20), and rotates the storage container 100 by 90 degrees by the rotational movement unit 4. (Step S22), the storage container 100 is moved to the radiation detection unit 2 by the slide moving unit 3 (Step S24). That is, the radioactivity measuring apparatus 1 moves the storage container 100 to the position of the rotary table 4 a of the rotary moving unit 4 by the slide moving unit 3. And the radioactivity measuring apparatus 1 rotates the storage container 100 90 degree | times by the rotational movement part 4 with the axial center which follows az direction. For this reason, in the storage container 100, the surface facing the y direction faces the x direction, and the surface facing the x direction faces the y direction. The storage container 100 rotated in this way is moved to a position facing the detector unit 20 of the radiation detection unit 2. Thereby, the surface of the storage container 100 that did not face the detector unit 20 in step S <b> 18 faces the detector unit 20.

  After moving the storage container 100 to the radiation detection unit 2, the control unit 10 measures the radiation on the remaining two surfaces of the storage container 100 (step S26). That is, the radiation of the two surfaces of the storage container 100 is measured by measuring the radiation of the surface facing the storage container 100 with the detector unit 20 facing the surface of the storage container 100 that has not been measured. When the control unit 10 measures the radiation on the two surfaces of the storage container 100, the control unit 10 moves the storage container 100 by the slide moving unit 3 (step S28), and ends this process. The control unit 10 may move the storage container 100 to the side opposite to the rotational movement unit 4 side, that is, the position of the storage container 100a.

  Next, a process of detecting the radioactivity of the storage container 100 from the radiation on each surface (six surfaces) of the storage container 100 detected by the process shown in FIG. 6 will be described with reference to FIGS. FIG. 7 is a flowchart showing an example of the operation of the radioactivity measuring apparatus according to the embodiment of the present invention. FIG. 8 is a graph showing an example of measurement results. Moreover, the process shown in FIG. 7 is realizable by performing a calculation in the radioactivity amount calculation part 5 based on the result detected by the radiation detection part 2, and various settings.

  The radioactivity amount calculation unit 5 acquires a spectrum for each detector unit 20 (step S40), adds the spectra for each surface, and calculates a spectrum for six surfaces (step S41). That is, the measurement result of six surfaces is analyzed, and the spectrum of each surface is detected. Specifically, a spectrum as shown in FIG. 8 is detected based on the measurement result output from the MCA 40 of each detector unit 20. In addition, the radioactivity amount calculation unit 5 may use the measurement result of the MCA 40 as it is as the analysis result or the analysis result obtained by processing the measurement result.

  When the radioactivity amount calculation unit 5 detects the spectrum for the six surfaces, the spectrum for the six surfaces is averaged to obtain one spectrum (step S44). Specifically, the average spectrum of the six surfaces is calculated from the detection result of the radiation spectrum acquired in step S41.

  Next, the radioactivity calculation unit 5 calculates the counting rate of Cs-137, Co-60, Co-58 (target radioactive substance) based on the average spectrum of the six surfaces (step S46). Specifically, the background, 0.662 MeV net peak count rate, band count rate, and detection lower limit count rate of Cs-137 are calculated. Also, Co-60 1.17 MeV background, 1.17 MeV net peak count rate, 1.33 MeV background, 1.33 MeV net peak count rate, band area count rate, 1.17 MeV detection A lower limit count rate and a detection lower limit count rate of 1.33 MeV are calculated. Calculate the background of Co-58, the net peak count rate of 0.811 MeV, and the lower detection limit count rate.

  Further, the radioactivity amount calculation unit 5 acquires the average density and the waste storage height of the waste in parallel with the processing from Step S40 to Step S46 described above (Step S47). Based on the volume of the storage container 100 and the detected weight of the storage container 100, the radioactivity amount calculation unit 5 acquires information on the average density of the waste (radioactive waste) included in the calculated storage container 100.

  Next, the radioactivity calculation part 5 sets a correction coefficient using the result of step S46 and step S47. The radioactivity amount calculation unit 5 uses the value calculated in step S46, and for Co-60, the peak average (average value of net peak count rates of 1.17 MeV and 1.33 MeV) and the peak ratio (= 1. A 17 MeV net peak count rate / 1.33 MeV net peak count rate) and a band / peak ratio (= band region count rate / 1.33 MeV net peak count rate) are calculated. In addition, the radioactivity amount calculation unit 5 calculates a band / peak ratio (= band region count rate / net peak count rate of 0.662 MeV) for Cs-137.

  After calculating each value, the radioactivity amount calculation unit 5 sets a correction coefficient from the waste average density, peak ratio, and band / peak ratio. For example, when Co-60 is detected (net peak count rate> detection lower limit count rate) and the peak average is larger than the threshold value, the correction coefficient is set using the peak ratio of Co-60. When Co-60 is detected and its peak average is below the threshold, a correction coefficient is set using the band / peak ratio of Co-60. When Co-60 is not detected (net peak count rate ≦ detection lower limit count rate) and Cs-137 is detected (net peak count rate> detection lower limit count rate), the band / peak ratio of Cs-137 To set the correction coefficient. If Co-60 is not detected (net peak count rate ≦ detection lower limit count rate) and Cs-137 is not detected (net peak count rate ≦ detection lower limit count rate), no correction coefficient is set.

  After calculating each value in step S46 and setting the correction coefficient in step S48, the radioactivity amount calculation unit 5 sets the values to Cs-137, Co-60, and Co-58 (target radioactive substances), respectively. The correction coefficient is multiplied (step S52). Specifically, for Co-60, the value obtained by dividing the band region count rate by 2 is multiplied by the correction coefficient, for Cs-137, the net peak count rate is multiplied by the correction coefficient, and for Co-58, the net Is multiplied by a correction coefficient.

  Further, the radioactivity amount calculation unit 5 sets a radioactivity conversion coefficient in parallel with the processing from step S40 to step S56 (step S54). Here, the radioactivity conversion coefficient is calculated by interpolating a conversion coefficient table prepared in advance (by measurement of the simulated object using an actual machine) using the average density and storage height of the radioactive waste. Can do.

  After calculating step S52 and setting the radioactivity conversion coefficient, the radioactivity amount calculation unit 5 multiplies the calculation result (the result calculated in step S52) by the radioactivity conversion coefficient (step S56). After calculating in step S56, the radioactivity amount calculation unit 5 evaluates the radioactivity based on the result (step S58), and ends this process. The radioactivity amount calculation unit 5 averages the γ rays emitted from each surface of the storage container 100 as described above, and evaluates the average amount of Co-58, Co-60, and Cs-137 of the γ rays. As a result, the total radioactivity etc. of the radioactive waste is calculated and evaluated.

  The radioactivity measuring apparatus 1 includes a detector unit 20 in which a plurality of detectors 22 including detection elements 24 in which the radioactive wastes stored in the storage container 100 are secondarily arranged are arranged from each surface of the storage container 100. In order to measure, the radioactivity amount of the whole radioactive waste stored in the storage container 100 can be measured with high accuracy. Specifically, according to the radioactivity measuring apparatus 1, the radioactivity of low-level radioactive waste generated from a nuclear facility such as a nuclear power plant can be measured with high accuracy.

  The radioactivity measurement apparatus 1 uses a semiconductor element containing CdTe or CdZnTe as the detection element 24, so that the detection element 24 having the energy resolution of γ-rays can be used, so that the target radioactivity can be measured with high accuracy. can do. Further, by using the detector 22 in which the detection elements 24 are two-dimensionally arranged, it is possible to appropriately detect the radiation to be measured even if a semiconductor element containing CdTe or CdZnTe is used. Detection can be suppressed. Further, by using a semiconductor element containing CdTe or CdZnTe as the detection element 24, the apparatus can be made inexpensive.

  By using a semiconductor element containing CdTe or CdZnTe as the detection element 24, the radioactivity measurement apparatus 1 can have higher γ-ray energy resolution than a scintillation detector and suppress the occurrence of problems caused by deliquescence. can do. Further, the radioactivity measuring apparatus 1 uses a semiconductor element containing CdTe or CdZnTe as the detection element 24, so that cooling with liquid nitrogen is unnecessary, and it can be arranged in a small space. Accordingly, the detection elements 24 can be arranged with high density.

  The radioactivity measurement apparatus 1 uses a semiconductor element containing CdTe or CdZnTe as the detection element 24, the detector 22 in which the detection element 24 is two-dimensionally arranged, and the detector unit 20 in which the detector 22 is two-dimensionally arranged. By measuring the radiation dose on the facing surface of the storage container 100, the detection elements 24 can be arranged with high density, and the measurement points can be made into a small space mesh. Thereby, the radioactivity measuring apparatus 1 can perform measurement with sufficient measurement accuracy regardless of the container shape and in a state where the container is stationary. The radioactivity measurement apparatus 1 can cope with various storage containers and storage balances of various radioactive wastes, and can increase the number of objects that can be measured.

  Here, FIG. 9A to FIG. 9C are schematic views each showing an example of a storage container storing radioactive waste. The storage container 100b shown in FIG. 9A is a container having the same size as the storage container shielding part 7. The storage container 100b stores the radioactive waste 110a in the entire region below the predetermined height. The storage container 100c shown in FIG. 9B is a container having the same size as the storage container shielding part 7. The storage container 100c stores the radioactive waste 110b in a partial region below a predetermined height. The storage container 102a shown in FIG. 9C is a container smaller than the storage container shielding part 7 by a certain percentage. The storage container 102a stores the radioactive waste 110c in a partial region below a predetermined height.

  As shown in FIGS. 9A to 9C, the radioactivity measurement apparatus 1 stores the radioactive waste even when the position of the radioactive waste in the storage container is various or the sizes of the storage containers are different. The amount of radioactivity in the container can be measured with high accuracy. Specifically, the detector unit 20 of the radiation detection unit 2 is divided into a plurality of detectors 22, and the detector 22 includes a plurality of detection elements 24, so that the radiation on each surface is divided into fine regions and measured. be able to. Thereby, it can suppress that a detection result shifts | deviates with the distance with a detection element, or relative positional relationship, and can suppress the detection omission of a radiation. Thereby, the radioactivity amount of the storage container can be measured with high accuracy. Thus, the object which can be measured can be increased by being able to respond to the storage balance of various storage containers and various radioactive wastes. Thereby, the radioactive quantity of the waste contained in the storage container of a different shape with a common detector specification and drive mechanism can be measured, and the versatility as an apparatus can be made high.

  The radioactivity measuring device 1 is also capable of measuring the radioactive wastes to be measured as low-level radioactive wastes. can do. That is, the amount of radioactivity of the storage container storing the concrete waste can also be measured. Thereby, the radioactivity measuring apparatus 1 measures the radioactivity resulting from the activation and surface contamination of concrete waste, and is also used as an apparatus for inspecting whether the radioactivity of the concrete waste is below the clearance level. be able to. In particular, the radioactivity measurement apparatus 1 can increase the area that can be measured by the detector unit 20, and can increase the storage container that can be detected by the radiation detection unit 2. Thereby, the large-capacity concrete waste stored in a container or the like can be collectively measured. Moreover, since the radioactivity measuring apparatus 1 can discriminate and measure radiation derived from nature and γ rays emitted from Co-60 and Cs-137 as described above, it is derived from activation of concrete waste and surface contamination. Γ-rays emitted from Co-60 and Cs-137 are measured by distinguishing them from natural radionuclides (K-40, etc.) originally contained in concrete, and derived from activation and surface contamination contained in concrete waste Radioactivity can be measured appropriately.

  In addition, as shown in FIG. 6, the radioactivity measurement apparatus 1 measures the radiation dose on the four surfaces of the storage container 100 in which the radiation detection unit 2 is linearly moved by the slide moving unit 3 and moved to the facing position. Thereafter, the slide moving unit 3 is linearly moved to the rotary moving unit 4, is rotated and moved by the rotary moving unit 4, is linearly moved by the slide moving unit 3, and is moved to the facing position on the remaining two surfaces of the storage container 100. Measure the radiation dose. Moreover, the radioactivity amount calculation part 5 acquires the radiation dose emitted from each of the six surfaces of the storage container 100 and averages the acquired radiation doses on the six surfaces.

  Thereby, the radioactivity measurement apparatus 1 can appropriately measure the radiation dose on the six surfaces of the storage container 100. Furthermore, since the radioactivity amount of the entire radioactive waste is calculated by averaging the radiation dose measured from each surface of the storage container 100, the radioactivity amount of the entire radioactive waste can be easily calculated. In addition, it is preferable that the radioactivity measuring apparatus 1 performs correction using the shape of the spectrum when calculating the radioactivity. Thereby, the influence of density unevenness in a measuring object and radiation source unevenness can be eased.

  In the detector unit 20 of the radioactivity measuring apparatus 1, it is preferable that the detectors 22 are two-dimensionally arranged on the surface facing the storage container 100 as in this embodiment. Thereby, the radiation dose of the target surface of the storage container 100 can be measured with a small number of measurements. The plurality of detectors 22 are arranged at least in a direction orthogonal to the moving direction of the storage container 100. The plurality of detectors 22 are preferably arranged in a region covering the entire region in the direction orthogonal to the moving direction of the storage container 100. Furthermore, it is preferable that the detector unit 20 includes the entire region where the arrangement region of the two-dimensionally arranged detectors 22 faces the storage container 100 as in the present embodiment. Thereby, since the radiation dose of the surface of the object of the storage container 100 can be measured at a time, it can measure in a short time.

  Here, when the detector unit 20 is not disposed on the entire surface of the storage container 100 in the moving direction, the radioactivity measuring apparatus 1 moves the storage container 100 by the slide moving unit 3 to thereby move the storage container 100 and the detector unit. The radiation of each surface of the storage container 100 is measured by repeating the process of moving the position of the storage container 100 relative to each other and shifting the region of the surface of the storage container 100 where the detector unit 20 detects the radioactivity a plurality of times. can do.

  The radioactivity measurement apparatus 1 of the present embodiment includes a radiation detection unit 2 and covers a range where the radiation detection unit 2 faces the surface of the storage container 100, and shields radiation from the outside of the apparatus to the radiation detection unit 2. The detecting unit shielding unit 6 is provided.

  According to this radioactivity measuring apparatus 1, since the radiation from the outside of the apparatus to the radiation detection section 2 is shielded by the detection section shielding section 6, the situation where the radiation detection section 2 detects the radiation from the outside of the apparatus is prevented. It is possible to accurately detect the radiation emitted from the storage container 100 to the outside.

  Moreover, the radioactivity measurement apparatus 1 of this Embodiment is provided with the storage container shielding part 7 which covers the storage container 100 at the time of detecting a radiation with the radiation detection part 2, and shields the radiation which reaches the storage container 100 from the outside of the apparatus. .

  According to this radioactivity measuring apparatus 1, radiation that reaches the storage container 100 from the outside of the apparatus is shielded by the storage container shielding part 7, and is released from the apparatus to the outside of the storage container 100 after reaching the storage container 100 once. Therefore, it is possible to accurately detect the radiation emitted from the storage container 100 to the outside.

  In the above-described embodiment, the slide moving unit 3 has been described as a configuration in which the radiation detection unit 2 is stationary and the storage container 100 is slid in the y direction. Although not clearly shown in the figure, for example, the slide moving unit 3 may be configured to slide the radiation detecting unit 2 in the y direction while keeping the storage container 100 stationary. The slide moving unit 3 may be configured to slide the storage container 100 and the radiation detection unit 2 in the direction opposite to the y direction. When the radiation detection unit 2 is slid in the y direction and the detection unit shielding unit 6 is provided, the slide movement unit 3 slides both the radiation detection unit 2 and the detection unit shielding unit 6. When the radiation detection unit 2 is slid in the y direction and the storage container shielding unit 7 is provided, the slide movement unit 3 slides both the radiation detection unit 2 and the storage container shielding unit 7.

  In the above-described embodiment, the slide moving unit 3 is configured to relatively slide the radiation detecting unit 2 and the storage container 100 in the horizontal direction, and the rotational moving unit 4 is configured to store the storage container with a vertical axis. Although described as a configuration in which 100 is rotated, the present invention is not limited to this. Although not clearly shown in the figure, for example, the slide moving unit 3 is configured to relatively slide the radiation detecting unit 2 and the storage container 100 in the vertical direction, and the rotation moving unit 4 is configured to store the storage container with a horizontal axis. 100 may be configured to rotate.

  The radioactivity measuring apparatus 1 preferably uses a rectangular parallelepiped storage container such as the regular hexahedron (cube) storage container 100 and the rectangular hexahedron (cuboid) storage container 102 of the above-described embodiment, and is a regular hexahedron (cube). More preferably. When the rectangular parallelepiped has a rectangular surface, the distance between the radiation detection unit 2 and the storage container 100 is not uniform before or after the storage container 100 is rotated by the rotational movement unit 4 or the storage container 100 is rotated. In some cases, the radiation detection unit 2 may not be arranged at a position where the surface is appropriately divided to detect radiation. As described above, the radioactivity measuring apparatus 1 is preferably a rectangular parallelepiped storage container, but it is not a rectangular parallelepiped, for example, a polyhedron other than a cylinder or a hexahedron or an irregularly shaped storage container may be used.

  The radioactivity measurement apparatus 1 may include a detection unit moving unit 6 that enables the radiation detection unit 2 to move in the x direction and the z direction (direction orthogonal to the sliding direction). By providing the detection unit moving unit 6, the radiation is placed at a suitable distance and a suitable position with respect to the surface of the storage container 100 before and after the storage container 100 is rotated by the rotational movement unit 4. The detection unit 2 can be arranged. Further, the storage container is preferably a rectangular parallelepiped as in the present embodiment. Thereby, the relationship between the detector unit 20 and the storage containers 100 and 102 can be made constant, and the amount of radioactivity can be measured with higher accuracy.

  Further, the radioactivity measuring apparatus 1 has a plastic scintillator arranged in a region where the detection element 24 of the radiation detection unit 2 is arranged, that is, a radiation measurement surface, and the radiation detection unit 2 is detected as a detection element 24 and a plastic scintillator. May be arranged in two layers. Thereby, detection efficiency can be improved. Further, in this case, the amount of radioactivity may be measured by proportionally dividing the gloss count of the plastic scintillator by the ratio of Co-60 and Cs-137 detected by the detection element 24. In this case as well, a semiconductor element containing CdTe or CdZnTe is used as the detection element 24, and the detection element 24 can be downsized, so that a scintillator can be provided.

  Next, another configuration of the detector will be described with reference to FIGS. FIG. 10 is a schematic diagram illustrating another example of the detector. FIG. 11 is a cross-sectional view of the detector shown in FIG. FIG. 12 is a schematic diagram illustrating a relationship between detection elements and switches of the detector illustrated in FIG. FIG. 13 is a schematic diagram illustrating another example of the relationship between the detection element and the switch.

  The detector 122 includes a cover 123, a plurality of detection elements 124, and a substrate 126. The cover 123 is a box that covers the entire surface of the region where the plurality of detection elements 124 are arranged, and the surface facing the storage container 100, that is, the surface on the storage container shielding part 7 side is opened. The cover 123 is fixed to the storage container shielding part 7 with screws or the like. The detection elements 124 are arranged in a two-dimensional array in the cover 123. Further, as shown in FIG. 11, in the detection element 124, a semiconductor detector 130 that reacts with radiation such as cadmium telluride (CdTe) is sandwiched between an electrode 132 and an electrode 134.

  The substrate 126 is a plate-like member and is fixed to the cover 123. A plurality of detection elements 124 are fixed to the substrate 126. Specifically, the board 126 is provided with a socket 140 at a connection position with the detection element 124. The socket 140 is a mechanism that fixes the detection element 124 in a detachable state. The socket 140 is an insertion port or the like into which the wiring of the detection element 124 is inserted. The detection element 124 is fixed to the socket 140 by inserting the terminal into the socket 140. Thereby, the detection element 124 is fixed to the substrate 126. Further, two sockets 140 according to the present embodiment are provided for one detection element 124, one socket 140 is connected to the wiring 128, and the other socket 140 is connected to the wiring 129. . The wirings 128 and 129 are wirings that connect the bias voltage source and the detection element 124. The wiring 128 is connected to the negative pole, and the wiring 129 is connected to the positive pole. The wiring 128 is connected to the electrode 132 through the socket 140. The wiring 129 is connected to the electrode 134 through the socket 140.

  The detector 122 can be easily attached to and detached from the substrate 126 by fixing the detection element 124 to the substrate 126 in a state where it can be attached and detached by the socket 140. Thereby, the detector 122 can easily replace the detection element 124.

  Next, in the detector 122, as shown in FIG. The switch 150 is provided for each detection element 124 and switches the corresponding detection element 124 on and off. When the switch 150 is turned on, the wiring 128 and the detection element 124 are connected, and a closed circuit is formed between the detection element 124, the wiring 128, the wiring 129, and the bias voltage source. The voltage of the bias voltage source is applied to 124. The detection element 124 to which the bias voltage is applied detects the radiation dose, and sends the detected result as a signal to the preamplifier 34 described above.

  The detector 122 can switch the detection element 124 that detects the radiation dose by providing the switch 150. Thereby, the detector 122 can detect the radiation dose in order by the detection element 124 by sequentially turning on the switches 150 and turning off the other switches. The control unit 10 can detect the performance of each detection element 124 by detecting a change in the detection result of the detection element 124 based on the detection result in order, and the detection element 124 is not broken. Can be determined.

  Here, the detector 122 shown in FIG. 12 is provided with the switch 150 corresponding to each detection element 124, but is not limited thereto. In the detector 122a shown in FIG. 13, the detection elements 124 are arranged in a two-dimensional array, that is, in a matrix direction. In the detector 122a, a plurality of detection elements 124 arranged in the row direction, that is, a wiring connected to the detection elements 124 in the same row is connected to the wiring 128 via the switch 150a. The switch 150a is provided for each row of the detection elements 124. When the detector 122a turns on the switch 150a, the detection element 124 in the row is connected to the wiring 128. In the detector 122a, a plurality of detection elements 124 arranged in the column direction, that is, wirings connected to the detection elements 124 in the same column are connected to the wiring 129 via the switch 150b. The switch 150b is provided for each column of the detection elements 124. When the detector 122a turns on the switch 150b, the detector elements 124 in that column are connected to the wiring 129.

  The detector 122a connects one detection element 124 to the plurality of switches 150a and 150b and connects one switch to the plurality of detection elements 124, that is, in the present embodiment, the detection element 124 is connected to the row. Dividing into columns, a switch is provided for each row and column to form a matrix. The detector 122a can detect the radiation dose with one detection element 124 by switching the switches 150a and 150b that are turned on in the rows and columns. Accordingly, the detector 122a can reduce the number of switches 150a and 150b with respect to the detection element 124. Thereby, a control object can be decreased.

  FIG. 14 is a perspective view showing a schematic configuration of the detection jig. FIG. 15 is an explanatory diagram for explaining a detection operation using the detection jig. A detection jig 170 shown in FIG. 14 is an inspection jig for detecting an abnormality of the detection element 124. The detection jig 170 includes a housing 172 in which an opening that can surround the detection element 124 is formed, and an inspection light source 174 disposed inside the housing 172. The inspection light source 174 emits light having a wavelength that can be detected by the detection element 124.

  As shown in FIG. 15, the detection jig 170 brings the opening of the housing 172 into contact with the substrate 126 at a position where the detection element 124 to be detected is disposed inside the opening of the housing 172 of the detection jig 170. As a result, the housing 172 and the substrate 126 come into contact with each other, and the detection element 124 and the inspection light source 174 are arranged in a space closed by the housing 172 and the substrate 126. In this state, light is emitted from the detection jig 170, and detection by the detection element 124 is performed. Based on the relationship between the signal detected by the detection element 124 and the light output from the detection jig 170, it can be confirmed whether the target light can be detected by the detection element 124. In this way, by using the detection jig 170, it is possible to inspect whether each of the detection elements 124 is abnormal.

  Next, an example of a detection element control method will be described with reference to FIGS. FIG. 16 is an explanatory diagram for explaining the function of the detection element. FIG. 17 is a graph showing an example of the relationship between the bias voltage of the detection element and the coefficient efficiency. 18 and 19 are graphs showing an example of the relationship between the detected pulse and time, respectively. FIG. 20 is a flowchart showing an example of the operation of the radioactivity measurement apparatus according to the embodiment of the present invention.

  As shown in FIG. 16, in the detection element 124, a semiconductor detector 130 that reacts with radiation such as cadmium telluride (CdTe) is sandwiched between an electrode 132 and an electrode 134. The electrode 132 is connected to the cathode (minus pole) of the bias voltage source 180, and the electrode 134 is connected to the anode (plus electrode) of the bias voltage source 180. When the detection element 124 is irradiated with γ rays while a bias voltage is applied, the holes move to the cathode (electrode 132) and the electrons move to the anode (electrode 134). Thereby, a current flows in the circuit. The radiation detection unit detects the amount of radiation by detecting the current flowing through the circuit as a pulse by the detection element 124 and detecting the number of pulses.

  Here, as shown in FIG. 17, in the detection element 124, the counting efficiency, that is, the ease of generation of pulses, varies depending on the applied bias voltage. Here, the counting efficiency is a value obtained by dividing the apparent radioactivity (count rate cpm) by the true radioactivity (decay rate dpm). The detection element 124 performs measurement with a voltage with high counting efficiency (the voltage V1 in FIG. 17), so that a pulse is easily generated and measurement with high sensitivity can be performed.

  As shown in FIG. 18, the detection element 124 is less likely to be counted off when the detected radiation dose is small (the number of pulses 190 is small). On the other hand, as shown in FIG. 19, the detection element 124 is likely to be counted off when the amount of detected radiation is large (the number of pulses 192 and 192a is large). For example, in FIG. 19, since the pulse 192a and the adjacent pulse 192a overlap each other, counting off is likely to occur.

  Therefore, the radioactivity measuring apparatus 1 of the present embodiment suppresses the occurrence of pulse counting by adjusting the bias voltage to be applied and adjusting the counting efficiency of the detection element 24. Specifically, the radioactivity measurement apparatus 1 performs measurement based on the setting (step S102), and detects the measured pulse count, that is, counts the detected pulse (step S104).

  The radioactivity measurement apparatus 1 counts the detected pulses and determines whether or not threshold value <pulse count number (step S106). If the radioactivity measuring apparatus 1 determines that the threshold value <the pulse count number (Yes in step S106), the radioactivity measuring apparatus 1 changes the bias voltage (step S108). Specifically, for example, as shown in FIG. 17, the bias voltage is changed from V1 to V2 or V3. The radioactivity measurement apparatus 1 may change the bias voltage in the direction in which the counting efficiency decreases, and the bias voltage may be increased or decreased. The radioactivity measuring apparatus 1 ends this process when the bias voltage is changed. If the radioactivity measuring apparatus 1 determines that the threshold value ≧ the pulse count number (No in step S106), the process is terminated.

  The radioactivity measurement apparatus 1 can suppress the occurrence of counting down due to excessive detection of the pulse count by changing the bias voltage applied to the detection element 124 based on the pulse count number. When the bias voltage is changed, the radioactivity measurement apparatus 1 can appropriately detect the radiation dose by converting the pulse count number based on the counting efficiency.

  21 and 22 are perspective views showing other examples of the storage container, respectively. In the said embodiment, although the storage container was made into the rectangular parallelepiped, it is not limited to this. As shown in FIGS. 21 and 22, the radioactivity measuring apparatus can also use cylindrical storage containers 202 and 204. Further, the direction of the storage container at the time of measurement is not particularly limited, and as shown in the storage container 202 shown in FIG. 21, the columnar side surface may be moved to the radiation detection unit 2 in a direction perpendicular to the sliding direction. As in the case of the storage container 204 shown in FIG. 22, the columnar top surface may be moved to the radiation detection unit 2 in a direction perpendicular to the sliding direction. Moreover, in the said embodiment, although the storage containers 202 and 204 were made into the column shape, it is not limited to this. A curved body having a curved surface can also be suitably used as the storage container. The storage container is preferably a rectangular parallelepiped or a curved body, but is not limited thereto.

  FIG. 23 is a perspective view showing a schematic configuration of another example of the radioactivity measurement apparatus. The radioactivity measuring apparatus 301 shown in FIG. 23 has a structure that can suitably measure the radiation dose of the cylindrical storage container 202. The radioactivity measurement apparatus 301 includes a radiation detection unit 302 and a moving mechanism 304 that moves the storage container 202 relative to the radiation detection unit 302. The radiation detection unit 302 includes a detector unit 320. The detector unit 320 is a ring-shaped member, and a plurality of detectors 322 are two-dimensionally arranged in the ring-shaped width direction and the circumferential direction. The detector 322 has a plurality of detection elements arranged two-dimensionally in the same manner as the detector described above. The moving mechanism 304 moves the storage container 202 along the cylindrical axial direction of the detector 322. Thereby, the radioactivity measurement apparatus 301 can measure the radiation dose at each part in the axial direction of the storage container 202 with the detector 322. The radioactivity measuring apparatus 301 moves the storage container 202 by the moving mechanism 304 and moves the storage container 202 relatively with the ring-shaped detector unit 320 and the storage container 202 facing each other, so that the detector unit 320 stores the radioactivity measurement apparatus 301. The radiation dose in the container 202 can be measured. When the detector unit 320 has a ring shape, the detector unit 320 has a single connected surface, and a plurality of detectors are arranged on the surface.

  Further, the radioactivity measuring device preferably has the detector unit arranged on all four sides or the entire circumference except for two sides in the direction of moving the storage container, but at least one side except for the two sides in the direction of moving the storage container. The detector unit may be disposed on the above surfaces (at least one surface of the surfaces excluding the two surfaces in the direction in which the storage container is moved).

  FIG. 24 is a perspective view showing a schematic configuration of another example of the radioactivity measurement apparatus. A radioactivity measurement apparatus 401 illustrated in FIG. 24 includes a radiation detection unit 402 and a moving mechanism 404 that moves the storage container 202 with respect to the radiation detection unit 402. The radiation detection unit 402 includes a detector unit 420 and a moving unit 409 that moves the detector unit 420 in the axial direction. The detector unit 420 is a member on the surface, and a plurality of detectors 422 are two-dimensionally arranged. The detector unit 402 moves the position of the detector unit 420 in the axial direction of the storage container 202 by the moving unit 409. The moving mechanism 404 rotates the storage container 202. The detector unit 420 is a mechanism that can move in the axial direction of the cylindrical storage container 202. The movement mechanism 404 moves the position of the storage container 202 facing the detector 422 by rotating the storage container 202 with respect to the detector 422. Thereby, the radioactivity measurement apparatus 401 can measure the radiation dose at each part in the axial direction of the storage container 402 with the detector 422. The radioactivity measuring apparatus 401 relatively moves the storage container 202 and the detector unit 420 by the radiation detection unit 402 and the moving mechanism 404, and relatively moves the detector unit 420 and the storage container 202 facing each other. Thus, the radiation amount of the storage container 202 can be measured by the detector unit 420.

  Even when the detector unit 420 does not have a shape covering the entire area of the arbitrary surface of the storage container 202 as in the radioactivity measuring apparatus 401, by arranging the detection elements of the detector 422 of the detector unit 420 two-dimensionally, The radiation dose of the storage container 202 can be suitably measured. That is, in the radioactivity measurement apparatus, the detector unit may be arranged on at least a part of at least one surface excluding two surfaces in the direction in which the storage container is moved. In FIG. 24, the cylindrical storage container 202 is used, but the radioactivity measurement apparatus 401 can also measure a rectangular parallelepiped storage container.

  FIG. 25 is a perspective view illustrating a schematic configuration of the radiation detection unit. Moreover, since the radiation detection part of the said embodiment can acquire the various effects mentioned above, although the element containing the semiconductor element containing CdTe or CdZnTe was used as a detection element, it is not limited to this. The radiation detection unit can use various elements as detection elements. For example, an element including a semiconductor element containing germanium (Ge) can be used as the detection element. The radiation detection unit 502 illustrated in FIG. 25 is disposed around the storage container 100. The radiation detection unit 502 is the same as that of the above-described embodiment except that the arrangement position of the detection element 524 is different. In the radiation detection unit 502, a detector 522 is disposed on each surface facing the storage container 100. In the detector 522, a plurality of detection elements 524 are arranged in a two-dimensional array.

  Even when the detection element 524 including a semiconductor element containing germanium (Ge) is used, the radiation detection unit 502 can appropriately measure the radiation dose of the storage container by arranging the detection elements 524 two-dimensionally.

DESCRIPTION OF SYMBOLS 1 Radioactivity measuring apparatus 1a Frame 2 Radiation detection part 3 Slide movement part 3a Rail 4 Rotation movement part 4a Rotation table 5 Radioactivity amount calculation part 6 Detection part shielding part 7 Storage container shielding part 8 Weight measurement part 10 Control part 20 Detector unit 22 Detector 24 Detection element 100 Storage container

Claims (16)

A radioactivity measuring device that measures the radioactivity of radioactive waste stored in a storage container,
A slide moving unit for linearly moving the storage container;
Radiation detection in which the slide moving unit is disposed in a path for moving the storage container, and a detector unit is disposed on at least one surface excluding two surfaces in a direction in which the slide moving unit moves the storage container. And
A radioactivity amount calculating unit that acquires the radiation dose emitted from each surface of the storage container detected by the radiation detection unit, and calculates the radioactivity amount of the entire radioactive waste by averaging the radiation doses of the acquired surface; With
The detector unit has a plurality of detectors,
The detector has a plurality of detection elements arranged in a two-dimensional array.   The radioactivity measuring apparatus according to claim 1, wherein the detection element is a semiconductor element containing CdTe or CdZnTe.   The control part which counts the pulse number detected with the said detection element, and changes the voltage applied to the said detection element when the counted pulse count number is more than a threshold value is provided. Radioactivity measuring device.   The radiation according to any one of claims 1 to 3, wherein the detector unit is arranged on each of four surfaces of the radiation detection unit except for two surfaces in a direction in which the storage container is moved. Performance measuring device.   The radioactivity measurement apparatus according to claim 4, further comprising a rotation moving unit that rotates and moves the storage container 90 degrees about an axis perpendicular to predetermined two opposite surfaces of the storage container. The radiation detection unit is linearly moved by the slide moving unit and measures the radiation dose on the four surfaces of the storage container moved to the facing position, and then is linearly moved to the rotary moving unit by the slide moving unit, The amount of radiation on the remaining two surfaces of the storage container that has been rotationally moved by the rotational movement unit, linearly moved by the slide movement unit, and moved to a facing position,
6. The radioactivity according to claim 5, wherein the radioactivity calculation unit acquires the radiation dose emitted from each of the six surfaces of the storage container, and averages the acquired radiation doses of the six surfaces. measuring device.   The radioactivity measuring apparatus according to any one of claims 1 to 6, wherein the detector unit has the detector arranged two-dimensionally on a surface facing the storage container.   The radioactivity measurement apparatus according to claim 7, wherein the detector unit includes an entire area of an area where the detectors are arranged in a two-dimensional manner, and an area where the detectors face each other.   The radioactivity measuring apparatus according to claim 1, wherein the storage container is a rectangular parallelepiped.   The radioactivity measurement apparatus according to claim 1, wherein the storage container is a curved body having at least one surface that is a curved surface.   2. A detection unit shielding unit that includes the radiation detection unit, covers a range where the radiation detection unit faces the surface of the storage container, and shields radiation from the outside of the apparatus to the radiation detection unit. To 10. The radioactivity measuring apparatus according to any one of 10 to 10.   The storage container shielding part which covers the said storage container at the time of detecting a radiation at the said radiation detection part, and shields the radiation which reaches the said storage container from the apparatus exterior is provided. The radioactivity measurement apparatus according to 1. The detector includes a terminal connected to the detection element, and includes a substrate that supports a plurality of detection elements,
The radioactivity measuring apparatus according to claim 1, wherein the detection element is connected to the terminal in a detachable state.   The radioactivity measurement apparatus according to any one of claims 1 to 13, wherein the detector includes a cover that covers a plurality of the detection elements other than a surface facing the storage container.   15. The detector according to claim 1, further comprising a switch that is provided between the detection element and the radioactivity amount calculation unit and switches the detection element that measures a radiation dose. The radioactivity measuring apparatus described. In the detector, the detection elements are arranged in a matrix,
The switch switches the connection between the plurality of detection elements and the activity amount calculation unit arranged in the same row or the same column,
16. The radiation according to claim 15, wherein the detection elements for measuring radiation dose are switched by sequentially switching a switch that connects a plurality of the detection elements and the activity amount calculation unit in the row and the column. Performance measuring device.

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