JP6366306B2 - Radioactivity measuring device for waste - Google Patents

Description

  The present invention relates to an apparatus for measuring the radioactive concentration of waste to determine whether or not the waste can be incinerated.

  The great tsunami caused by the 2011 off the Pacific coast of Tohoku Earthquake not only destroyed houses and buildings in the affected areas, but also caused serious nuclear accidents. For this reason, many of the wastes (disaster wastes) generated by the collapse of houses and buildings are contaminated with radioactivity, and it is indispensable for the reconstruction of the earthquake disaster to treat them early. .

  For the treatment of the above waste, at present, the radioactivity concentration of the waste is first measured, and the waste whose radioactivity concentration is below a certain standard value can be incinerated, but the radioactivity concentration is the above standard value. Waste that exceeds the limit must be strictly managed as radioactive waste. Here, in order to measure the radioactive concentration of waste, the radioactive measuring apparatus for waste is used.

  As a conventional radioactivity measuring apparatus, an apparatus for measuring the radioactivity concentration of a subject (for example, waste) from the bottom of the subject with a scintillator has been proposed (see, for example, Patent Document 1). In this apparatus, by arranging a scintillator inside the radiation shielding box and placing the subject on the radiation shielding box, the radioactivity concentration of the subject can be easily measured with a simple configuration. Has been. Further, Patent Document 1 describes that measurement may be performed after a subject is accommodated in a flexible container bag (hereinafter abbreviated as a flexible container).

Utility Model Registration No. 3186377

  By the way, when the subject is the above-mentioned disaster waste housed in a flexible container, the disaster waste is made of rubble of different sizes, shapes, and specific gravities, resulting in variations in the density of the disaster waste inside the flexible container. . For this reason, the disaster waste accommodated in the flexible container has a higher radioactivity concentration toward the bottom and non-uniform radioactivity concentrations in the vertical and circumferential directions.

  Therefore, in the radioactivity measurement apparatus described in Patent Document 1, when the subject is the disaster waste and contained in the flexible container, the radioactivity concentration increases toward the bottom of the subject. A value higher than the average radioactivity concentration is measured in the vertical direction. In this case, safety is ensured, but the radioactivity concentration is not measured with high accuracy.

  Further, in order to measure the average radioactivity concentration in the vertical direction of the subject, it is conceivable to separately arrange a scintillator on one side of the subject. However, when the subject is the above-mentioned disaster waste and contained in a flexible container, since the subject has a non-uniform radioactivity concentration in the circumferential direction, the average radioactivity concentration in the circumferential direction cannot be measured with high accuracy. .

As described above, the conventional radioactivity measuring apparatus has a problem that the radioactivity concentration cannot be measured with high accuracy with respect to the waste (particularly disaster waste) stored in the flexible container.
Accordingly, an object of the present invention is to provide a radioactive measuring apparatus for waste that can ensure safety and can measure the radioactive concentration with high accuracy.

In order to solve the above-mentioned problem, the radioactive measuring apparatus for waste of the present invention has a mounting table on which the waste contained in a storage bag is mounted, and a mount on which the mounting table is provided, A radioactive measuring device for waste that measures the radioactive concentration of an object,
A rotation mechanism for rotating the mounting table with respect to the frame ;
Side measurement means capable of measuring the radiation dose from the waste rotating by the mounting table on the side of the waste,
Bottom measurement means capable of measuring the radiation dose from the waste placed on the table above the waste;
A weight measuring device capable of measuring the weight of the waste placed on the mounting table;
From the radiation dose measured by the side measuring means and the weight measured by the weight measuring device, the average radioactivity concentration in the vertical direction of the waste, the radiation dose measured by the bottom measuring means and the weight And a calculation unit for calculating the radioactive concentration on the safe side of the waste .

  Moreover, the radioactive measuring apparatus for waste which concerns on Claim 2 of this invention is a scintillator by which the bottom part measurement means in the radioactive measuring apparatus for waste of Claim 1 is arrange | positioned at the rotating shaft of the mounting base. Is.

  Further, the radioactive measuring apparatus for waste according to claim 3 of the present invention is a scintillator in which the bottom measuring means in the radioactive measuring apparatus for waste according to claim 1 is arranged eccentrically from the rotation axis of the mounting table. It is what is.

  In addition, the radioactive measuring apparatus for waste according to claim 4 of the present invention includes a plurality of side measuring means in the radioactive measuring apparatus for waste according to any one of claims 1 to 3 in the vertical direction. It is a scintillator arranged.

  According to the waste radioactivity measuring apparatus, safety can be ensured and the radioactivity concentration can be measured with high accuracy.

It is a top view of the radioactive measuring apparatus for waste in embodiment of this invention. It is a side view of the radioactive measuring apparatus for waste. It is an enlarged plan view of the radioactive measuring apparatus for waste. It is an enlarged side view of the radioactive measuring apparatus for waste. It is a block diagram for demonstrating the self-supporting control panel of the radioactive measuring apparatus for waste.

Hereinafter, a radioactive measuring apparatus for waste according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1 and FIG. 2, the object of which the radioactive concentration is measured by the waste radioactivity measuring apparatus is a flexible container bag 7 (an example of a storage bag, hereinafter abbreviated as a flexible container 7). Disaster waste 8 (hereinafter simply referred to as “waste 8”). The use of the flexible container 7 for storing the waste 8 has various advantages, unlike using a drum can. The merit is, for example, that cheap and large-capacity waste 8 can be accommodated, that it is light and foldable so that it can be easily handled in the field, and can be incinerated together with the accommodated waste 8. However, since the waste 8 accommodated in the flexible container 7 is made of rubble having different sizes, shapes, and specific gravities, the density of the waste 8 varies within the flexible container 7. For this reason, as shown in FIGS. 3 and 4, the waste 8 accommodated in the flexible container 7 has a higher radioactivity concentration (as well as a radiation dose γ) toward the bottom, and the radioactivity concentration in the vertical and circumferential directions. (Radiation dose γ) is also non-uniform.

  As shown in FIG. 1 and FIG. 2, the waste radioactivity measuring apparatus 1 is arranged on a gantry 5 having a moving wheel 6 (may be a fixed leg) provided on a lower surface thereof, and the gantry 5. Radiation measuring instruments 2-4. Although not shown, a wall (having a door in part) is provided on the periphery of the mount 5 and a roof is provided on the upper end of the wall. That is, a room in which the radiation measuring devices 2 to 4 are arranged is formed by the mount 5, the wall, and the roof.

  The radiation measuring devices 2 to 4 are disposed on the pedestal body 2 disposed at the center of the gantry 5, the measuring column body 3 disposed on one end side of the gantry 5, and the other end side of the gantry 5. A self-supporting control panel 4 is provided. In the pedestal 2, the waste 8 accommodated in the flexible container 7 is placed together with the pallet 9. The measurement column 3 measures the average radiation dose γ in the vertical direction of the waste 8 placed on the pedestal 2 by a side measurement means (described later in detail) 33. The self-supporting control panel 4 controls the pedestal 2 and the measurement column 3, while measurement data is input from the pedestal 2 and the measurement column 3, and calculation is performed based on the input measurement data. Is what you do.

  The pedestal 2 includes a weight measuring device 21 installed on the gantry 5, a support tool 22 installed on the weight measuring device 21, and a bottom measuring means installed on the support tool 22 (in detail). 23, a disc-shaped turntable (which is an example of a mounting table) 24 installed on the support 22, and a rotation mechanism that rotates the turntable 24 around a vertical axis 25 ( (Not shown). Next, the constituent members of the pedestal 2 will be described in detail in order from above. The turntable 24, which is the uppermost constituent member of the pedestal 2, has the waste 8 accommodated in the flexible container 7 placed on the pallet 9 and the waste 8 on the vertical axis 25 (hereinafter referred to as the vertical axis 25). Then, it is rotated around the rotation axis 25). Although not shown, the rotation mechanism includes a horizontal gear concentric with the turntable 24 fixed inside the turntable 24, and a motor that is provided on the support 22 and rotates the horizontal gear by a pinion. The bottom measuring means 23 can measure the radiation amount γ from the waste 8 placed on the turntable 24 from below the waste 8. The support 22 is a table having a top plate 22t and legs 22l, and is a non-rotating object that is not synchronized with the rotation of the turntable 24. The top plate 22t fixes the bottom measuring means 23 and the motor, and supports the turntable 24 rotatably around the rotation shaft 25 by a rotation transmitting portion (for example, a guide rail, a bearing, etc.) 26. is there. The weight measuring device 21 can measure the weight of the waste 8 placed on the turntable 24. The motor (not shown), the bottom measuring means 23 and the weight measuring device 21 are all connected to the self-sustained control panel 4 by wires 11.

  Here, as shown in FIG. 4, the side measuring means 33 can measure the radiation dose γ from the waste 8 placed on the turntable 24 from the side of the waste 8. These are the radiation dose measuring devices 13 arranged at equal intervals in the vertical direction with three (or more) in the vertical direction. The bottom measuring means 23 is a radiation dose measuring device 13 disposed on the rotating shaft 25 of the turntable 24. The radiation dose measuring devices 13 constituting the side measuring means 33 and the bottom measuring means 23 are respectively a scintillator 13s, a thick cylindrical portion 13c that covers the scintillator 13s and is made of a radiation shielding material (such as lead). And a flange 13f provided on the outer periphery of the thick-walled cylindrical portion 13c. The thick cylindrical portion 13c has a thickness of about 25 to 50 mm and does not cover the entire scintillator 13s, but exposes the radiation dose measurement side (waste 8 side) of the scintillator 13s by about 50 mm in the length direction. ing.

  The measurement column body 3 includes a column portion 31 fixed to the gantry 5 and the side measurement means 33 held by the column portion 31. The column part 31 has three holes 32 into which the radiation dose measuring devices 13 are inserted in order to hold the three radiation dose measuring devices 13 constituting the side measuring means 33. Of course, these hole portions 32 are arranged at equal intervals in the vertical direction. The side measuring means 33 is connected to the self-supporting control panel 4 by the wiring 11.

  As shown in FIGS. 1 to 3, the self-supporting control panel 4 has a radiation shielding plate (for example, a lead glass plate) for the safety (prevention of exposure) of the operator O who operates the self-supporting control panel 4. 14 is provided. That is, the radiation shielding plate 14 shields the radiation from the waste 8 and prevents the operator O from being exposed in the operation space S on the front side of the self-supporting control panel 4.

  Although not shown, the self-supporting control panel 4 includes a measurement start button for rotating the turntable 24 by the motor and starting measurement by the radiation dose measuring device 13 and the weight measuring device 21. The self-supporting control panel 4 includes a timer that measures the measurement time by the radiation dose measuring device 13 and a rotation speed adjustment dial that adjusts the rotation speed of the turntable 24, although not shown. Further, as shown in FIG. 5, the self-supporting control panel 4 includes a side dose input unit 41 to which measurement data of the radiation dose γ from the three radiation dose measuring devices 13 constituting the side measurement means 33 are input. The measurement data of the radiation dose γ from the vertical direction averaging unit 42 for averaging the three measurement data input to the side dose input unit 41 and the radiation dose measuring device 13 constituting the bottom measurement means 23 are input. A bottom amount input unit 43 and a weight input unit 44 to which weight measurement data from the weight measuring device 21 is input. The vertical direction average unit 42 adds up the radiation dose γ measurement data input from the three radiation dose measuring instruments 13, and adds up the totaled measurement data 3 (radiation dose measurement constituting the side measurement means 33. The number of vessels 13). That is, the vertical direction average unit 42 has three radiation doses arranged at equal intervals (at different heights) in the vertical direction even if the radiation dose γ from the waste 8 is not uniform in the vertical direction. The average radiation dose γ in the vertical direction of the waste 8 is calculated by averaging the measurement data from the measuring device 13. Further, the self-supporting control panel 4 includes a side time averaging unit 45 that averages the measurement data calculated by the vertical direction averaging unit 42 in unit time, and the measurement data input to the bottom amount input unit 43 in unit time. A bottom time averaging unit 46 for averaging. The side time average unit 45 and the bottom time average unit 46 integrate the measurement data with the measurement time measured by the timer in order to average the measurement data in unit time, and the integrated measurement data Divide by measurement time. Furthermore, the self-supporting control panel 4 divides the measurement data averaged in the unit time by the side time average unit 45 and the bottom time average unit 46 by the measurement data input to the weight input unit 44, respectively. A calculation unit (an example of a calculation unit) 47 is provided. The radioactivity concentration calculation unit 47 measures the radioactivity concentration (hereinafter referred to as an average radioactivity concentration in the vertical direction) based on the radiation dose γ measured by the side measurement unit 33 and the bottom measurement unit 23. The radioactivity concentration based on the radiation dose γ (hereinafter referred to as “safety side radioactivity concentration”) is calculated. In addition, the self-sustained control panel 4 includes a storage unit 48 that stores the radioactivity concentrations calculated by the radioactivity concentration calculation unit 47, and an output unit 49 that can output these radioactivity concentrations to an external device. Prepare.

  The gist of the present invention is as follows. First, the radiation dose measuring devices 13 (which constitute the side measuring means 33) arranged at equal intervals in the vertical direction, and the measurement data from these radiation dose measuring devices 13 are averaged. The vertical average unit 42 and the radioactivity concentration calculation unit 47 convert the radioactivity concentration to an average in the vertical direction even if the radioactivity concentration increases toward the bottom like the waste 8 contained in the flexible container 7. The radioactivity concentration is to be obtained. Secondly, by rotating the waste 8 with respect to the radiation dose measuring device 13 fixed to the gantry 5, the radioactive concentration is not uniform in the circumferential direction like the waste 8 accommodated in the flexible container 7. Even in such a case, the measurement data is averaged in unit time, that is, an average radioactivity concentration is obtained in the circumferential direction. Third, the radiation dose measuring device 13 (which constitutes the bottom measuring means 23) capable of measuring the radiation dose γ from the waste 8 from below the waste 8, and the radioactivity concentration calculating section 47, provide a safe side. The radioactivity concentration is to be obtained. Fourth, when the radiation dose γ of the waste 8 is measured by the weight measuring device 21 on which the turntable 24 is installed via the support 22, the weight of the waste 8 is measured. is there.

Hereinafter, the usage method of the said radioactive measuring apparatus 1 for wastes is demonstrated.
First, the waste 8 is accommodated in the flexible container 7 and placed on the pallet 9. Then, the waste 8 accommodated in the flexible container 7 is transported to the waste radioactivity measuring device 1 together with the pallet 9 by a forklift or the like, and the waste 8 is placed on the turntable 24 together with the pallet 9. At this time, as shown in FIG. 3, the planar center of the flexible container 7 in which the waste 8 is accommodated is positioned on the rotating shaft 25 of the turntable 24.

  Next, the worker O stands in the operation space S and presses the measurement start button on the self-supporting control panel 4. Then, the waste 8 rotates with the pallet 9 together with the turntable 24 around the rotation shaft 25. Then, as shown in FIG. 4, the radiation dose γ is measured by three radiation dose measuring devices 13 (specifically scintillators 13 s) in the vertical direction constituting the side measuring means 33 from the side of the rotating waste 8. Is measured, and a radiation dose γ is measured from below the waste 8 by a radiation dose measuring device 13 (specifically, a scintillator 13s) constituting the bottom measuring means 23. At this time, the weight measuring device 21 measures the weight of the waste 8.

  The measurement data of the radiation dose γ measured by the side measurement unit 33 is averaged in the vertical direction by the vertical direction average unit 42 and then averaged by the side time average unit 45 in unit time. Also, the measurement data of the radiation dose γ measured by the bottom measuring means 23 is averaged by the bottom time averaging unit 46 in unit time. Based on the averaged measurement data and the weight measurement data from the weight measuring device 21 by the radioactivity concentration calculation unit 47, the average radioactivity concentration in the vertical direction, the radioactivity concentration on the safe side, and Is calculated. The calculated average radioactivity concentration in the vertical direction and the safety-side radioactivity concentration are stored in the storage unit 48 and can be output to an external device by the output unit 49.

Thus, according to the said radioactive measuring apparatus 1 for waste, a radioactive density | concentration can be measured with high precision by obtaining an average radioactive density | concentration in a perpendicular direction and a circumferential direction.
Further, by obtaining the radioactive concentration on the safe side, safety can be ensured and radioactive contamination of the pallet 9 can also be detected.

Furthermore, since the weight of the waste 8 is measured when measuring the radiation dose γ of the waste 8, the radioactivity concentration can be obtained in a short time.
In addition, since the radiation dose measuring device 13 is detachable, when the waste radiation measuring device 1 is moved, by removing the radiation measuring device 13 from the waste radioactive measuring device 1, expensive radiation can be obtained. Damage to the quantity measuring device 13 (especially the scintillator 13s) can be prevented.

  Further, since the radiation dose measuring device 13 constituting the bottom measuring means 23 is disposed on the rotating shaft 25 of the turntable 24, the radiation dose γ is reliably measured from below the waste 8 even when the flexible container 7 is small. Therefore, the radioactivity concentration can be measured with higher accuracy.

  Further, the thick cylindrical portion 13c has a thickness of about 25 to 50 mm, and the radiation dose measuring side (waste 8 side) of the scintillator 13s is exposed by about 50 mm in the length direction. 13, the radiation dose γ from other than the waste 8 is not measured, and the radioactivity concentration can be measured with higher accuracy.

  By the way, in the said embodiment, although scintillator 13s was not demonstrated in detail, in order to cope with the high concentration contamination of the waste 8, for example, a plastic scintillator is used.

  Moreover, although the radiation dose measuring device 13 which comprises the side part measurement means 33 was demonstrated to be hold | maintained at the pillar part 31 in the said embodiment, you may have a withdrawing / withdrawing mechanism to the waste 8. Specifically, although not shown, a distance sensor for measuring the distance between the pillar portion 31 and the waste 8 and an actuator for moving the radiation dose measuring device 13 in and out of the waste 8 are provided in the pillar portion 31. And a controller for controlling the actuator so that the distance between the radiation dose measuring device 13 and the waste 8 is constant based on the distance measured by the distance sensor. With this configuration, since the measurement of the radiation dose γ measured by the side measurement means 33 becomes more accurate, the radioactivity concentration can be measured with higher accuracy.

  Furthermore, in the above embodiment, the radiation dose measuring devices 13 constituting the side measuring means 33 are described as being arranged at equal intervals. However, the present invention is not limited to this, and the measurement of the radiation dose γ is higher. Appropriate intervals for accuracy are selected.

  In addition, in the above-described embodiment, the radiation dose measuring device 13 constituting the bottom measurement unit 23 is described as being disposed on the rotating shaft 25 of the turntable 24. However, even if the radiation measuring device 13 is disposed eccentrically from the rotating shaft 25. Good. With this configuration, since the measurement of the radiation dose γ on the safe side becomes more accurate, the radioactivity concentration can be measured with higher accuracy. Further, a separate actuator that can move the radiation dose measuring device 13 (which constitutes the bottom measuring means 23) in the horizontal direction may be provided.

Furthermore, although the said embodiment demonstrated as measuring the radioactive concentration of the waste 8 accommodated in the flexible container 7, it is not limited to this.
Further, although the radiation dose measuring device 13 has not been described in detail in the above embodiment, it is appropriately selected based on the required accuracy, and a survey meter, a Geiger counter, or the like may be used.

DESCRIPTION OF SYMBOLS 1 Radioactivity measuring apparatus 2 Waste base 3 Measurement column 4 Self-supporting control panel 5 Stand 7 Flexible container 8 Waste 11 Wiring 13 Radiation dose measuring device 13s Scintillator 13c Thick cylindrical part 13f Flange 14 Radiation shielding plate 21 Weight measurement Device 22 Support 23 Bottom measurement means 24 Turntable 31 Column 33 Side measurement means

Claims (4)

A radioactive measuring device for waste having a mounting table on which waste stored in a storage bag is mounted, and a mount on which the mounting table is provided, and measuring the radioactive concentration of the waste,
A rotation mechanism for rotating the mounting table with respect to the frame ;
Side measurement means capable of measuring the radiation dose from the waste rotating by the mounting table on the side of the waste,
Bottom measurement means capable of measuring the radiation dose from the waste placed on the table above the waste;
A weight measuring device capable of measuring the weight of the waste placed on the mounting table;
From the radiation dose measured by the side measuring means and the weight measured by the weight measuring device, the average radioactivity concentration in the vertical direction of the waste, the radiation dose measured by the bottom measuring means and the weight A calculation unit for calculating the safety-side radioactivity concentration of the waste ,
A radioactive measuring device for waste, comprising:   2. The radioactive measuring apparatus for waste according to claim 1, wherein the bottom measuring means is a scintillator disposed on the rotating shaft of the mounting table.   2. The radioactive measuring apparatus for waste according to claim 1, wherein the bottom measuring means is a scintillator arranged eccentrically from the rotation axis of the mounting table.   The radioactive measuring apparatus for waste according to any one of claims 1 to 3, wherein the side measuring means is a plurality of scintillators arranged in the vertical direction.

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