JPH08189973A - Survey meter - Google Patents

Abstract

PURPOSE: To measure a dose rate in the periphery of a setting place two- dimentionally by fixing a plurality of detecting parts with an optional solid angle to a base body and making the detecting parts directional. CONSTITUTION: A rotary device 30 is fixed to a frame 10 and a rotary shaft 40 is coupled. A frame part 12 is fixed on the shaft 40, on which a base body 20 is fixed. The base body 20 is spherical and can be divided half up and down at its center. Six detecting parts are fixed at the outer surface of the base body 20. Specifically, a horizontal detecting part 61 is set at each horizontal plane where the base body 20 is divided half to face the outer surface of the base body 20. Moreover, upper detecting parts 62 directed 45 deg. upward and lower detecting parts 43 directed 45 deg. downward are set at the outer surface of the base body 20 at positions shifted 90 deg. from the detecting parts 61. Since the base body 20 is fixed to the rotary shaft 40 and moreover, every two horizontal, upper and lower detecting parts 61, 62, 63 are fixedly disposed, the plurality of detecting parts never measure a dose rate from the same radiation source, so that the measurement directivity is improved. The planar dose rate at a setting place of a survey meter can be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a survey meter, and more particularly to measuring a dose rate from a radiation source, which has detectors in a plurality of directions and directivity to each detector. The present invention relates to a survey meter that can measure the dose rate around the installation site in a plane or three-dimensionally if necessary.

[0002]

Conventionally, a survey meter has been used as a measuring device for measuring a dose rate from a radiation source. Most of the conventionally used survey meters here measure the dose rate in the atmosphere of the installation location.

Therefore, if the survey meter is installed indoors, the dose rate of the atmosphere in the room can be measured. On the other hand, there are cases where it is desired to measure only the dose rate from a certain direction. At such times, conventionally, a tube portion was provided at the tip of the survey meter detection unit.
By fixing the lead collimator in the cylinder of the cylinder and fixing lead around the detection unit including the cylinder, it is possible to measure the dose rate corresponding to the amount of the light passing through the hole of the collimator.

With this structure, only the dose rate from a certain direction can be measured, but when the radiation distribution in a certain room is measured using such a survey meter, the detectors are detected in many directions. It was necessary to measure the dose rate each time, and to specify the radiation distribution in a room by the aggregated dose rate in each direction.

However, even if the measurement is performed in this way, it is not always possible to accurately measure the dose rate depending on the direction in which the detector is directed. Therefore, it is conceivable that the survey meter to which the lead collimator is fixed can be freely rotated by a predetermined angle, and the dose rate is measured while rotating by a predetermined angle. Certainly, if you do this, the direction in which the detector is directed changes by a predetermined angle, so
It is considered that the radiation distribution in a room can be specified relatively flatly or three-dimensionally.

However, even if such a measure is taken, if the dose rate changes from moment to moment, it is not possible to measure the radiation distribution in a certain room at the same time because it is not possible to measure the radiation distribution in each room at the same time.

[0007]

Therefore, the invention according to claim 1 of the present invention is such that a plurality of detecting portions for measuring a dose rate are fixed to a substrate at an arbitrary solid angle, whereby a survey meter is provided. The purpose of the present invention is to provide a survey meter that can measure the dose rate at the installation site in a plane to some extent.

According to the second aspect of the present invention, the four detectors for measuring the dose rate are fixed on the same surface around the base in a state shifted by 90 degrees. Is fixed on the same surface when the substrate is cut,
The purpose of the present invention is to provide a survey meter capable of measuring the dose rate at the place where the survey meter is installed in a plane.

According to a third aspect of the present invention, one horizontal detecting portion is provided so as to face the outer surface of the base body which is a horizontal plane obtained by dividing the base body into two equal parts in the vertical direction. On the outer surface of the base body at each of the positions deviated by 90 degrees, an upper detection section facing upward by 45 degrees and a lower detection section facing downward by 45 degrees are provided. It is intended to provide a survey meter capable of three-dimensionally measuring the dose rate at a place.

The invention according to claim 4 is the same as claim 1 or 2.
Further, in addition to the object of the invention described in 3, the object is to provide a survey meter that can easily determine the fixed position of the detection unit and the like because the base body is a sphere. In addition to the object of the invention described in claim 1, 2, 3 or 4, the invention according to claim 5 is formed so that a lead ball can be held inside the base body. Therefore, by holding the lead ball, It is an object of the present invention to provide a survey meter that does not measure the dose rate from the same radiation source with a plurality of detectors.

According to the invention of claim 6, in addition to the object of the invention of claim 5, a lead ball is formed so as to be put in and taken out freely. Therefore, the lead ball is put in after the survey meter is installed and the lead ball is taken after the measurement. The purpose of the present invention is to provide a survey meter that can be easily installed or removed because the survey meter can be removed after removing. Further, in the invention according to claim 7, in addition to the object of the invention according to claim 1, 2, 3, 4, 5 or 6, the base is rotatably formed.
It is an object of the present invention to provide a survey meter that can perform two-dimensional measurement or three-dimensional measurement more accurately, although there is a time lag in measurement.

[0012]

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention is such that a plurality of detecting portions for measuring a dose rate are provided on a substrate in an arbitrary three-dimensional shape. It is characterized by being fixed at the corner. Further, the invention according to claim 2 is characterized in that four detecting portions for measuring a dose rate are fixed on the same surface around the base in a state of being shifted by 90 degrees.

According to a third aspect of the present invention, one horizontal detecting portion is provided so as to face the outer surface of the base body which is a horizontal plane obtained by bisecting the base body in the vertical direction. 4 diagonally on the outer surface of each substrate at 90 degrees
It is characterized in that an upper detecting section facing upward by 5 degrees and a lower detecting section facing downward by 45 degrees are provided. The invention according to claim 4 is characterized in that, in addition to the constitution of the invention according to claim 1, 2 or 3, the base body is a sphere.

The invention according to claim 5 is the invention according to claim 1,
In addition to the constitution of the invention described in 2, 3 or 4, a feature is that a lead ball can be held inside the base body. Further, the invention according to claim 6 is characterized in that, in addition to the constitution of the invention according to claim 5, lead balls are formed so as to be freely inserted and taken out. Furthermore, the invention of claim 7 relates to claim 1, 2, 3,
In addition to the constitution of the invention described in 4, 5, or 6, the base is rotatably formed.

[0015]

According to the first aspect of the present invention, a plurality of detectors for measuring the dose rate are fixed to the substrate at an arbitrary solid angle. Therefore, compared with a survey meter having at least a single detector. The dose rate can be measured three-dimensionally. Further, when the base body is made rotatable as in the seventh aspect of the invention, by rotating the base body, it is possible to measure the dose rate in a plane on which the respective detection units are fixed.

According to a second aspect of the present invention, four detectors for measuring the dose rate are provided on the same surface around the substrate.
It is fixed in a staggered state. Here, the detector can measure the dose rate within a certain angle range, so this angle is
If the angle is 90 degrees or more, the dose rate can be measured planarly by detecting the dose rate by these four detection sections at the same time.

Further, even if the angle at which the dose rate can be measured is 90 degrees or less, the dose rate on the surface on which the respective detectors are fixed can be measured almost flatly. Further, when the base is made rotatable as in the seventh aspect of the invention, by rotating the base, it is possible to surely measure the dose rate on the surface on which the respective detectors are fixed in a planar manner.

By such detection, in a situation where it is desired to measure the dose rate in the horizontal direction, but the dose rate from the vertical direction can be ignored, the survey meter becomes a very practical survey meter. Further, in the invention according to claim 3, one horizontal detecting portion is provided so as to face the outer surface of the base body which is a horizontal plane obtained by dividing the base body into two equal parts in the vertical direction. On the outer surface of the base body at each of the positions deviated from each other, there are provided an upper detection section that is inclined 45 degrees upward and a lower detection section that is inclined 45 degrees downward.

Therefore, if the detector can measure the dose rate in the range of 90 degrees or more, the dose rate in the room in which the survey meter is installed can be measured three-dimensionally. Also,
Even if the angle at which the dose rate can be measured is 90 degrees or less, the dose rate in the room in which the survey meter is installed can be measured almost three-dimensionally. Further, when the substrate is made rotatable as in the seventh aspect of the invention, the dose rate in the room in which the survey meter is installed can be reliably measured three-dimensionally by rotating the substrate.

Further, when the base body is formed into a spherical body as in the invention of claim 4, indexing of the fixed position of the detecting portion or the like or rotation as in the invention of claim 6 can be performed easily and stably. It is a thing. Further, when the lead ball is formed so as to be held inside the base as in the invention of claim 5, the lead ball is held inside the base so that the dose rate from the same radiation source can be detected by the plurality of detection units. No longer measuring
The directivity in measurement is improved.

Further, as in the invention described in claim 6, when a lead ball is formed so as to be put in and taken out freely, after installing the survey meter, the lead ball is put in and after the measurement, the lead ball is removed and then the survey meter is removed. it can. Therefore, the survey meter can be transported, installed, or removed with the extremely heavy lead balls removed, and workability is greatly improved.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall front view showing an embodiment of the present invention. 2 to 4 show a substrate used in the present invention. FIG. 2 is a front view, FIG. 3 is a plan view, and FIG. 4 is a bottom view. FIG. 5 shows a detector mounted on the base body, and shows a schematic front view and a schematic exploded front view. FIG. 6 is a schematic perspective view of a charge amplifier holder mounted on the detection unit. 7 and 8 show a rotary shaft that rotates together with the base fixed. FIG. 7 is a schematic front view and FIG. 8 is a schematic plan view. 9 to 11 show a tray and a duct pipe for taking out lead balls. FIG. 9 is a perspective view, FIG. 10 is a plan view, and FIG. 11 is a partially cutaway schematic front view. FIG. 12 is a schematic diagram of a main electric circuit. FIG. 13 is a perspective view showing another embodiment of the substrate used for the survey meter. FIG. 14 is a plan view showing still another embodiment of the substrate used in the survey meter.

First, the outline of the present invention will be described with reference to FIG. This survey meter is formed by fixing various parts to a frame 10 having casters 11 attached to the lower part. Here, the frame 10 has a rectangular frame portion 1 for fixing the base body 20 above the upper end surface.
2 is formed, and further four columns 13 are provided so as to expand downward from the frame 12. Therefore, since it has a trapezoidal shape as a whole, the base 20 is provided above the frame 12.
It is also stable when fixed.

Further, a rotating device 30 is fixed to the frame 10 at an intermediate position in the height direction. A rotary shaft 40 is connected to the output side of the rotating device 30. Further, at the upper end of the rotary shaft 40, the frame portion 1
The base body 20 located above 2 is fixed, and the base body 20 is formed to rotate by the operation of the rotating device 30. It should be noted that what is provided between the base body 20 and the frame portion 12 in the drawing is a heavy-duty bearing 14 for smoothly rotating the base body 20. Further, provided between the frame portion 12 and the rotating device 30 is a tray 50 for taking out the lead balls from the base body 20, and a duct pipe 51 is connected.

Although not shown in FIG. 1, the frame 10 is provided with an operation panel. Hereinafter, various parts will be described with reference to FIGS.
2 to 4 show a substrate 20 used in the present invention. FIG. 2 is a front view, FIG. 3 is a plan view, and FIG. 4 is a bottom view.

In these figures, the base body 20 is formed as a sphere so that it can be vertically divided into two at the center of the front view. Then, six detection units 60 are fixed to the outer surface of the base body 20. Specifically, one horizontal detector 61 is provided so as to face the outer surface of the base 20 that is a horizontal plane obtained by bisecting the base 20 in the vertical direction, and further, 90 degrees in the horizontal direction from both horizontal detectors 61. On the outer surface of the base body 20 at each of the displaced positions, the upper detection unit 62 that faces upward at an angle of 45 degrees.
And a lower detection unit 63 that is inclined 45 degrees downward.

Furthermore, the inside of the base 20 is hollow, and a lead ball injection port 21 is formed in the upper part. A base flange 22 for fixing the rotary shaft 40 is provided in the lower portion, and a lead ball discharge port 23 is provided in the center of the base flange 22. Further, the base flange 22 is provided with a fixing port 24 for fixing to the rotating shaft 40, and a cord outlet for taking out the cords from the horizontal detecting unit 61, the upper detecting unit 62 and the lower detecting unit 63. 25 are provided. Here, although not shown, a shutter device is provided at the discharge port 23.

Such a base body 20 has a rotary shaft 40.
After fixing the horizontal detection unit 61, the upper detection unit 62, and the lower detection unit 63 to each two, lead balls are injected into the inside from the injection port 21, so that the plurality of detection units 60 have the same structure. Since the dose rate from the radiation source is no longer measured, the directivity in measurement is improved. Further, when the base body 20 is formed of a stainless plate having a thickness of 0.5 mm and a diameter of 210 mm, about 30 to 40 kg of lead balls having a diameter of 2 mm can be injected into the base body 20.

Next, referring to FIG. 5, the detector 60 mounted on the base 20 will be described. The detection unit 60 includes a cap 6 screwed into one side of a cylindrical collimator storage unit 64.
5 is fixed, and the charge amplifier holder 66 and the nipple 67 are fixed on the other side. here,
A lead collimator can be stored in the collimator storage portion 64. Here, the lead collimator is for improving the radiation directivity or adjusting the dose rate by making an arbitrary hole in the center.

The charge amplifier holder 66 is shown in FIG.
It is shown in. In FIG. 6, one end of the charge amplifier holder 66 is released, and the other end is provided with a connector 68 whose end projects from the nipple 67. Further, inside the charge amplifier holder 66 on the released side, a charge amplifier board 69 is provided, and this charge amplifier board is provided with a photodiode holder 70 fixed on the released side of the charge amplifier holder 66. The photodiode 71 fixed to the back surface is connected.

Next, referring to FIGS. 7 and 8, the rotary shaft 40 that fixes the base body 20 and rotates together will be described. The rotating shaft 40 has a lower end fixed to the rotating device 30 and an upper end fixing the base body 20. Therefore, a shaft flange 41 fixed to the base flange 22 is provided at the upper end of the rotary shaft 40. A lead ball discharge passage 42 is provided from the center of the shaft flange 41 to the center side in the height direction of the rotary shaft 40. The discharge passage 23 is provided from the discharge port 23 of the rotary shaft 40.
The lead ball can be discharged through the 2. Furthermore,
A fixing port 43 for fixing the base body 20 is provided in the shaft flange 41, and a code for taking out codes from the horizontal detecting unit 61, the upper detecting unit 62, and the lower detecting unit 63 provided in twos. An outlet 44 is provided.

Next, the tray 50 and the duct tube 51 for taking out the lead balls will be described with reference to FIGS. The tray 50 is formed in a donut shape and is fixed to the frame 10. The rotary shaft 40 rotates at the central hole. Further, the fixed height to the frame 10 is determined by the discharge passage 42 of the rotary shaft 40.
It's height. Further, the inside of the tray 50 is inclined downward toward the duct pipe 51. Furthermore, the duct pipe 51 is connected from the lower end of this downward slope to the floor where the survey meter is installed.

Therefore, the lead balls discharged from the discharge port 23 of the base 20 reach the tray 50 through the discharge passage 42 of the rotary shaft 40, and are eventually discharged to the vicinity of the floor through the duct pipe 51. is there. Next, the system of the main electric circuit will be described with reference to FIG. The survey meter according to the present invention has two electric circuits.

The first system is a system for radiation detection, amplification, and recording, and the second system is a system for a control / rotating device 30 for rotating the substrate 20. Here, in the first system, the detection signal from the detection unit 60 provided on the substrate 20 is received, the detection signal is amplified by the main amplification circuit 80, and the result is output to the recorder 81 and the liquid crystal display unit 82. It is a thing.

Further, in the second system, the rotation angle display section 83
Further, a right rotation switch 84 and a left rotation switch 85 for rotating the base body 20 are provided on the frame front panel 15 fixed to the frame 10, and a control signal from this is provided to the rotating device 30 via an amplifier circuit and a synchronizing circuit 86. Is input to. Next, the operation and operation of the survey meter according to the present invention will be described.

First, the survey meter with the lead balls taken out is carried to the inside of the room for measuring the dose rate and installed at a predetermined position. At this time, the casters 11 are attached to the lower portion of the frame 10, so that it is easy to carry, and since it is possible to carry the lead balls of 30 to 40 kg taken out, it is light and easy to handle.

After being installed at a predetermined position, the base 2
A predetermined amount of lead balls are injected into the base 20 through the injection port 21 at the upper part of 0. At this time, the discharge port 2 at the bottom of the base 20
The shutter device 3 is closed. Then, the electric circuit is energized to start the measurement. When starting the measurement in this way, it is desirable to perform 0-point adjustment in advance for each of the horizontal detection unit 61, the upper detection unit 62, and the lower detection unit 63 provided two by two. For such 0-point adjustment, first, each detection unit 60 is taken out, the 0-point adjustment is performed separately, and further, after each detection unit 60 is fixed to the base body 20, the 0-point including the floating capacitance or the power supply noise is again included. It is desirable to make adjustments.

Further, each detecting section 60 is set so as to detect only radiation having an incident angle of about 45 degrees by using a lead collimator. Then, the measurement is started. Further, at the time of this measurement, a control signal is output to the rotating device 30 so that the rotating shaft 40 is intermittently rotated at intervals of 15 degrees.

Then, the dose rate is measured every 6 points at intervals of 15 degrees from the origin. The measured dose rate is recorded in the recorder and also displayed on the liquid crystal display. From each dose rate recorded in the recorder, the dose rate in the room where the survey meter is installed can be measured three-dimensionally.

By the way, Table 1 shows the results of measuring the dose rate in the middle of the two heat exchangers of the reactor shutdown cooling system of the nuclear power plant. In Table 1, A and B are the lower detection unit 63, C and D are the upper detection unit 62, and E and F
Is the horizontal detector 61. The numbers 0 to 180 are the rotation angles of the base 20. Furthermore, Table 1
The number inside shows the dose rate, and the unit is 0.1 mSv / hr.

Further, at the start of the measurement, the horizontal detectors 61 indicated by E and F are set so as to be perpendicular to the line connecting the two heat exchangers.

[0042]

[Table 1]

Further, by using the six detectors 60, the base 20
When is rotated 180 degrees, A and B, C and D, and E and F
However, since the respective plane positions are shifted by 180 degrees, as a result, 360 degrees are covered. Therefore, Table 2 shows the measurement results shown in Table 1 converted to 360 degrees.

[0044]

[Table 2]

Here, each of I, II, and III is a dose rate of I: 45 degrees obliquely downward measured by the lower detection unit 63, II: 45 degrees obliquely upward measured by the upper detection unit 62, and III: horizontal plane.

As in Table 1, the numbers in Table 2 indicate dose rates, and the unit is 0.1 mSv / hr. From this result, for example, in the vicinity of (1) 90 ° and 105 °, the dose rate from the horizontal direction is high, but the dose rate from the oblique direction does not change significantly. Therefore, the dose rate from the horizontal direction is high. (2) In the vicinity of 165 degrees and 180 degrees, the dose rate from the horizontal direction is high, and the dose rate from 45 degrees obliquely upward is also high.
Therefore, the dose rate from above is slightly higher than in the horizontal direction. (3) The dose rate from any direction is high near 225 degrees, 240 degrees, and 255 degrees. Therefore, the dose rate from the vertical direction is high. I was able to confirm that.

As a result, it was confirmed that the survey meter according to the present invention can three-dimensionally measure the dose rate at the installation site. Another embodiment of the substrate 20 used in the survey meter will be described with reference to FIG. In this embodiment, the base body 20 is formed in a cubic shape. A detection unit 60 is provided on each of the six surfaces of the base body 20.

Further, the base body 20 is formed in a hollow shape,
Further, a lead ball injection port 21 is formed on the upper surface. A large bearing 16 is fixed to the lower portion of the base body 20 to facilitate rotation. Each detector 60 is formed in a horizontally long shape, and a lead collimator is used so that the incident angle in the longitudinal direction is 9
It is set so that radiation up to about 0 degrees can be detected.

Therefore, when the dose rate is measured by the substrate 20, the dose rate of the room in which the survey meter is installed can be three-dimensionally measured by rotating the substrate 20 by 180 degrees. Next, referring to FIG. 14, another embodiment of the substrate 20 used in the survey meter will be described.

In this embodiment, the base body 20 is formed as a sphere, six detection units 60 are provided on the base body 20, and the base body 20 is rotatably formed by three orthogonal axes. . Specifically, the base body 20 is rotatably supported about one axis, for example, the y-axis via the inner ring 17, and the inner ring 17 is further centered on the other one axis, for example, the x-axis. Is rotatably supported by the outer ring 18 as a shaft. On top of that, this outer ring 18
Together with the inner ring 17 and the base body 20, another uniaxial shaft,
For example, it is rotatable about the z axis.

At the time of actual measurement, the measurement can be performed while rotating any one of the axes, and particularly for a portion to be precisely measured, the rotation of the other axis can be used for the measurement. Of course, if three-axis rotation is used, the number of detection units 60 can be reduced.

Although not shown in more detail, by holding lead balls inside the base 20, a plurality of detectors 6 are provided.
When 0, the dose rate from the same radiation source is not measured, and the directivity in measurement is improved. Further, in the above-described embodiments, the trapezoidal shape has been described as an example of the shape of the frame 10, but it may be another shape or a box body instead of the frame 10. Furthermore, the rotating device 30
It is also possible to directly mount and use on the floor where the survey meter is installed.

The shape of the base body 20 has been described by taking a sphere and a cube as an example. However, other shapes such as a cylindrical shape,
It may be plate-shaped or polyhedral. At that time, the detection unit 6
With respect to the number of 0, four survey units 60 for measuring the dose rate are fixed on the same surface around the base 20 in a state of being shifted by 90 degrees, and the base 20 is rotated by 90 degrees, whereby a survey meter is provided. It will be possible to measure the dose rate at the installation location in a plane.

Further, in the above description, the case where the rotating device 30 is attached and the base 20 is rotated has been described as an example. However, for example, 4 for measuring the dose rate on the same plane around the base 20 is used. Fix the individual detection units 60 in a state of being shifted by 90 degrees,
It is also possible that it is not rotated. Here, the detection unit 60
Since the dose rate within a certain angle range can be measured, if this angle is 90 degrees or more, the dose rates on the surface on which the respective detection units 60 are fixed are detected by simultaneously detecting the dose rates by these four detection units 60. The rate can be measured in a plane.

By such detection, in a situation in which it is desired to measure the dose rate in the horizontal direction, but the dose rate from the vertical direction can be ignored, the survey meter becomes a very practical survey meter. Furthermore, it is possible to recognize an abnormal increase in radiation by measuring the change over time of the dose rate by measuring at preset times. Further, the base body 20 is a horizontal plane obtained by dividing the base body 20 into two parts in the vertical direction.
One horizontal detection unit 61 is provided so as to face the outer surface, and further, the upper detection is performed at an angle of 45 degrees upward on the outer surface of the base body 20 at a position deviated from the horizontal detection units 61 by 90 degrees in the horizontal direction. The part 62 and the lower detection part 6 that faces downward at an angle of 45 degrees.
3 may be provided and the base body 20 may not be rotated.

At this time, if the detector 60 can measure the dose rate in the range of 90 degrees or more, the dose rate in the room in which the survey meter is installed can be measured three-dimensionally. Even if the angle at which the dose rate can be measured is 90 degrees or less, the dose rate in the room in which the survey meter is installed can be measured almost three-dimensionally. Furthermore, it is possible to recognize an abnormal increase in radiation by measuring the change over time of the dose rate by measuring at preset times.

Further, the rotation of the base body 20 is not limited to the uniaxial rotation or the triaxial rotation as in the embodiment, and the axis direction can be arbitrarily set. In addition, although it has been described that the rotation is controlled to be intermittently rotated, the rotation can be performed by moving the rotating device 30 only while the switch is operated, or can be completely manually rotated.

Further, the detecting means in the detecting section 60 only needs to be able to directly or indirectly detect radiation as an electromagnetic wave, and in the embodiment, a photodiode is used as an example. It is not limited to the photodiode as long as the rate can be detected. For example, a Geiger-Muller tube or the like can be used.

[0059]

As described above, according to the invention of claim 1 of the present invention, a plurality of detecting portions for measuring a dose rate are fixed to a substrate at an arbitrary solid angle.
The dose rate at the survey meter installation site can be measured flatly to some extent. According to the second aspect of the present invention, four detecting portions for measuring the dose rate are fixed on the same surface around the base in a state of being shifted by 90 degrees,
By fixing these four detectors on the same surface when the substrate is cut, the dose rate at the place where the survey meter is installed can be measured in a plane.

According to the third aspect of the present invention, one horizontal detecting portion is provided so as to face the outer surface of the base body which is a horizontal plane obtained by dividing the base body into two halves in the vertical direction. On the outer surface of the base body at each of the positions deviated by 90 degrees, an upper detection section facing upward by 45 degrees and a lower detection section facing downward by 45 degrees are provided. The dose rate at a place can be measured three-dimensionally.

Further, the invention according to claim 4 is the same as claim 1, 2
Alternatively, in addition to the effect of the invention described in item 3, since the base body is a sphere, it is possible to easily determine the fixed position of the detection unit and the like. The invention of claim 5 is the same as claim 1,
In addition to the effect of the invention described in 2, 3, or 4, since a lead ball is formed so as to be able to be held inside the substrate, by holding the lead ball, the dose rate from the same radiation source can be detected by a plurality of detection units. Is something that is not measured.

According to the invention of claim 6, in addition to the effect of the invention of claim 5, a lead ball is formed so as to be put in and taken out freely. Therefore, after installing the survey meter, the lead ball is put in and the lead ball is taken after the measurement. Since the survey meter can be removed after removing it, it can be easily installed or removed. Further, in addition to the effect of the invention described in claim 1, 2, 3, 4, 5 or 6, the invention described in claim 7 forms the substrate rotatably, so that there is a time lag in measurement, but it is flat. The measurement or three-dimensional measurement can be performed more accurately.

[Brief description of drawings]

FIG. 1 is an overall front view showing an embodiment of the present invention.

FIG. 2 is a front view of a substrate used in the present invention.

FIG. 3 is a plan view of a substrate used in the present invention.

FIG. 4 is a bottom view of a substrate used in the present invention.

5A and 5B are a schematic front view and a schematic exploded front view of a detection unit mounted on a base.

FIG. 6 is a schematic perspective view of a charge amplifier holder attached to a detection unit.

FIG. 7 is a schematic front view of a rotating shaft that fixes a base body and rotates together.

FIG. 8 is a schematic plan view of a rotary shaft that rotates together with the base fixed.

FIG. 9 is a perspective view of a tray and a duct tube for taking out a lead ball.

FIG. 10 is a plan view of a tray and a duct pipe for taking out lead balls.

FIG. 11 is a partially cutaway schematic front view of a tray and a duct tube for taking out a lead ball.

FIG. 12 is a schematic system diagram of a main electric circuit.

FIG. 13 is a perspective view showing another embodiment of the substrate used in the survey meter.

FIG. 14 is a plan view showing still another embodiment of the substrate used in the survey meter.

[Explanation of symbols] 10 frame 11 caster 12 frame portion 13 column 14 heavy load bearing 15 frame front panel 16 large bearing 17 inner ring 18 outer ring 20 base 21 inlet 22 base flange 23 discharge port 24 fixed port 25 cord outlet 30 Rotating device 40 Rotating shaft 41 Shaft flange 42 Discharge passage 43 Fixing port 44 Cord outlet 50 Receiving tray 51 Duct pipe 60 Detecting part 61 Horizontal detecting part 62 Upper detecting part 63 Lower detecting part 64 Collimator storing part 65 Screw cap 66 Charge amplifier holder 67 Nipple 68 Connector 69 Charge amplifier board 70 Photodiode holder 71 Photodiode 80 Main amplification circuit 81 Recorder 82 Liquid crystal display 83 Rotation angle display 84 Right rotation switch 85 Left rotation Switch 86 Amplifier circuit and synchronization circuit

Claims (7)

[Claims] 1. A survey meter, wherein a plurality of detectors for measuring a dose rate are fixed to a substrate at an arbitrary solid angle. 2. A survey meter, wherein four detectors for measuring a dose rate are fixed on the same surface around a base in a state shifted by 90 degrees. 3. A horizontal detection unit is provided so as to face the outer surface of the base body which is a horizontal plane obtained by dividing the base body into two parts in the vertical direction.
Further, an upper detection section facing diagonally upward by 45 degrees and a lower detection section facing diagonally downward by 45 degrees are provided on the outer surface of the base body at positions shifted by 90 degrees in the horizontal direction from the both horizontal detecting sections. A characteristic survey meter. 4. The survey meter according to claim 1, 2 or 3, wherein the substrate is a sphere. 5. The survey meter according to claim 1, wherein a lead ball is formed so as to be retained inside the base body. 6. The survey meter according to claim 5, wherein lead balls are formed so as to be freely inserted and taken out. 7. The survey meter according to claim 1, wherein the base is rotatably formed.