JP4475990B2 - Environmental radiation dose meter and environmental radiation management system - Google Patents

Description

  The present invention relates to an environmental radiation dose meter for measuring environmental radiation dose (hereinafter simply referred to as a dose) and radiation dose rate (hereinafter simply referred to as a dose rate) to monitor fluctuations and abnormalities in environmental radiation, and It relates to the environmental radiation management system used.

An environmental radiation dosimeter (hereinafter referred to as an environmental dosimeter) is a measuring device for measuring fluctuations and abnormalities in environmental radioactivity by measuring dose and dose rate at a certain place. FIG. 5 shows an example of an environmental dosimeter according to the prior art, in which (a) is a perspective view showing the external appearance, and (b) is a block diagram showing its circuit configuration.
The environmental dosimeter 100 includes a radiation detection unit 2 and a support unit 1 that supports the radiation detection unit 2. The radiation detection unit 2 has the circuit configuration shown in FIG. 5 (b), and the intersection point with the surface of the perpendicular line extending from the center position of the detection unit surface of the detection element perpendicularly to the detection unit surface is front-facing. A position 21 is provided, and a display unit 22 for displaying measurement results and the like is provided below the position 21.
The internal circuit includes a detection element + amplifier 23 that detects and amplifies incident radiation as a current pulse, and a plurality of discrimination circuits-1 to discrimination-n that discriminate the output pulses of the amplifier at several different energy levels. Discriminating circuit 24, counting circuit 25 for counting the signals output from the individual discriminating circuits for each discriminating circuit, and CPU 26 for calculating a predetermined dose or dose rate by calculating the count value corresponding to each discriminating circuit EEPROM 28 for storing various information, infrared transmission / reception circuit 27 for exchanging various information such as commands and output data from the data management device etc. with the data management device, etc. The power unit 29 is a power source.

The CPU 26 stores various information including measurement results in the EEPROM 28, and outputs the information to the infrared transmission / reception circuit 27 as necessary, or receives external information input to the infrared transmission / reception circuit 27. Predetermined processing. Usually, the measurement result is transmitted from the environmental dosimeter 100 side to the data management device or the like via the infrared transmission / reception circuit 27 when a predetermined time or a set value is exceeded.
The detection element + amplifier 23 to the counting circuit 25 are collectively referred to as a radiation detector, and hereinafter simply referred to as a detector.
Here, the plurality of discriminating circuits 24 are provided to cope with the dose equivalent, and the average energy is obtained by discriminating the energy of the radiation captured by the detecting element, and the conversion corresponding to the average energy is performed. This is because a predetermined energy characteristic is secured using the coefficient. As a prior art considering such correction of energy characteristics, for example, a technique described in Japanese Patent Laid-Open No. Hei 3-239986 is known (see Patent Document 1).
JP-A-3-239986

In the environmental dosimeter 100 as described above, the direction characteristic of sensitivity is adjusted within a certain range, for example, within ± 20%, so that detection can be performed with substantially the same sensitivity when radiation enters from any direction. However, in general, the sensitivity from the front is high, and the sensitivity from the side often shows a directional characteristic of the sensitivity that has decreased to the above lower limit. There are variations due to the incident direction of radiation.
In this way, the environmental dosimeter is compensated for the direction characteristics, so even if the environmental dosimeter detects a radiation with a dose or dose rate that exceeds the set value, the direction from which the radiation has mainly entered. Even if an abnormality such as a dose can be detected, the direction of occurrence of the abnormality cannot be specified. Of course, it is not possible to specify the location of the abnormality.
An object of the present invention is to provide an environmental dosimeter that can specify the direction of the main source of radiation when measuring radiation with a dose or dose rate equal to or higher than a set value and has excellent measurement accuracy It is another object of the present invention to provide an environmental radiation management system capable of obtaining dose data useful for elucidating the cause of abnormalities including the radiation emission location even when the monitoring target area is wide.

  The invention of claim 1 has a main radiation detector (radiation detector 2a) that measures the radiation dose and dose rate of the environment based on the output of the radiation detector, and a large sensitivity to radiation coming from the front direction. And a plurality of sub-radiation detectors (sub-detector-1 to sub-detector-4) arranged around the main radiation detection unit so that the directions of the sensitive surfaces are different from each other, Direction switching means (direction switching unit 3) having a rotation mechanism (turn table 32) capable of rotating the main radiation detection unit in a horizontal plane and arbitrarily setting the front position of the main radiation detection unit, and measurement by the main radiation detection unit When the radiation dose or the radiation dose rate reaches or exceeds a set value, the respective count values of the plurality of sub-radiation detectors are compared to identify the direction of incidence of the most radiation from which the most radiation comes. , This most radiation incident Arithmetic processing means (CPU 26a) for driving the rotation mechanism of the direction switching means so that the front position of the main radiation detection unit faces in the direction.

Since the most radiation incident direction is specified by the outputs of a plurality of sub-radiation detectors having large directional characteristics, the direction of the location where a large amount of radiation is emitted can be known. Furthermore, since the direction switching means directs the front of the main radiation detection unit in this direction, variations in measurement values due to the direction characteristics of the main radiation detection unit are reduced, and highly accurate measurement is possible.
The invention according to claim 2 is the invention according to claim 1, wherein the radiation dose or the radiation dose rate measured by the main radiation detection unit reaches a set value or more, and the front side of the main radiation detection unit is the most radiation incident direction by the direction switching means. When it is directed to, the time interval of counting of the main radiation detection unit is shortened, and more detailed time variation data of the radiation dose or the radiation dose rate is acquired.
If the dose or dose rate measured by the main radiation detector exceeds the set value, there is a high possibility of an abnormal situation or its precursor stage. Following is very effective in elucidating the cause of abnormalities. In addition, since the data is acquired with the front of the main radiation detection unit facing the most radiation incident direction, highly accurate measurement can be performed.

The invention of claim 3 collects dose data by communicating with a plurality of environmental radiation dose meters (environmental dosimeter-1 to environmental dosimeter-n) according to claim 1 arranged in a distributed manner. by a radiation control system comprising a data management apparatus for performing radiation control monitored Elijah (data management device 5), the data management apparatus, each environmental dosimeters location and at a predetermined position for a particular In the case where it has a position specifying means (position specifying means 51) consisting of a storage unit and a calculation unit that stores the calculation program, and any of the environmental radiation dosimeters measures a radiation dose or a radiation dose rate greater than a set value , While causing the environmental radiation dose meter to transmit dose data including the measurement value and the direction of incidence of the most frequently specified radiation, and immediately request each environmental radiation dose meter to transmit the dose data, each environmental radiation Based on the dose data and said storage means information of location stored in the obtained from the quantity meter, it performs arithmetic processing for identifying a radiation-emitting locations in the monitored area.

  When any environmental dosimeter measures a dose or dose rate that is greater than or equal to the set value, the data management device will display dose data that includes data on the maximum radiation incidence direction of each of multiple environmental dosimeters that are distributed. Are collected, and the calculation process for specifying the radiation emission location is performed, so that the radiation emission location can be grasped quickly and reliably.

According to the first aspect of the present invention, when a radiation having a dose or dose rate equal to or higher than a set value is measured, the direction of the main source of radiation can be specified, and the front of the main radiation detector is in that direction. Therefore, an environmental dosimeter having excellent measurement accuracy can be provided.
According to the invention of claim 2, when the front of the main radiation detection unit is directed in the direction of incidence of the most radiation, the counting time interval of the main radiation detection unit is shortened compared to the normal time, and the dose and dose rate are reduced. Since detailed time variation data is acquired, it is possible to obtain dose data more useful for elucidating the cause of abnormality.
According to the invention of claim 3, when any environmental radiation dosimeter which is distributed on the monitored area is measured the dose or dose rate of more than a set value, a plurality of environmental radiation dose by the data management device Since dose data including the most radiation incident directions is collected from the meter and the position specifying calculation is performed, the radiation emission location (radiation generation source) can be grasped quickly and reliably.

In addition to the main detector, the environmental dosimeter according to the present invention includes a plurality of sub-detectors having large directional characteristics, specifies the incident direction of radiation from the ratio of the count values of the sub-detectors, and The feature of the environmental radiation management system according to the present invention lies in the direction of the main detector in the direction, the incident direction of radiation obtained from a plurality of the environmental dosimeters arranged in a distributed manner, in other words, the direction of the radiation source, The position of the radiation source is specified by the data management device (central computer) based on the positions of these environmental dosimeters.
Embodiments of an environmental dosimeter and an environmental radiation management system according to the present invention will be described below in detail based on examples. In addition, the same code | symbol shall be attached | subjected to the part of the same function as a prior art.

FIG. 1 is a perspective view showing an external appearance of an embodiment of an environmental dosimeter according to the present invention, and FIG. 2 is a block diagram showing a circuit configuration of this embodiment.
This embodiment includes a radiation detection unit 2a, a direction switching unit 3 for mounting the radiation detection unit 2a on the turntable 32, and a support unit 1 for supporting them at a predetermined height. This embodiment is different from the conventional example in that it includes a direction switching unit 3 and is accompanied by a function added to the CPU 26a of the radiation detection unit 2a.
In the following, a description will be given mainly of parts different from the conventional example.
The external part of the radiation detection unit 2a and the part that detects and stores the radiation value by detecting the radiation are exactly the same as the conventional example, and the outer surface is marked with a “+” mark indicating the front position 21, The display unit 22 is provided, and includes a detection element + amplifier 23, a plurality of discrimination circuits 24, a counting circuit 25, a CPU 26a, an EEPROM 28a, an infrared transmission / reception circuit 27, and a power supply unit 29a.

The direction switching unit 3 has a square thin box shape, is supported by the support unit 1, has a turntable 32 on which the radiation detection unit 2 a is mounted at the center, and has sub-detections at the centers of the four side surfaces. Device-1 front position 311, sub-detector-2 front position 312, sub-detector-3 front position 313, and sub-detector-4 front position 314 are marked with a "+" mark. Corresponding to this position, the direction specifying sub-detector-1 331, the direction specifying sub-detector-2 332, the direction specifying sub-detector-3 333 and the direction specifying sub-detection not shown in FIG. Device-4 334 is located. Hereinafter, the sub-detector for direction identification is abbreviated as a sub-detector.
The four sub-detectors are arranged with their front faces in the vertical direction of the four side surfaces of the direction switching unit 3, and the sensitivity from the rear is significantly smaller than the sensitivity from the front side. The configuration, for example, a configuration in which a material having a large mass is disposed behind the detection element to absorb the radiation from the rear, and all four are adjusted to the same sensitivity. By looking at the magnitude relationship between the count values of these four sub-detectors, you can know the direction in which the radiation is incident, and if you calculate the ratio of the count values, the most radiation is incident from the count ratio. The direction (the most radiation incident direction) can be specified.

For example, if the count value of sub-detector-1 is the largest, and the count values of sub-detector-2 and sub-detector-4 are almost the same, the direction of incidence of the most radiation is the front direction of sub-detector-1. If the count value of sub-detector-2 is larger than the count value of sub-detector-4, the direction of incidence of the most radiation is inclined toward sub-detector-2 from the front direction of sub-detector-1. become. If the relationship between the count value ratio and the slope is obtained in advance, this slope can be determined based on the measured count value ratio. Since such a relationship is a relationship common to the four sub-detectors, by providing the four sub-detectors, it is possible to specify the radiation incident from any direction.
Note that such a direction specification is not limited to four sub-detectors, and is possible if three or more sub-detectors are provided.

The turntable 32 is a means for adjusting the direction of the radiation detection unit 2a, and is driven by a turntable drive unit 321 (for example, a pulse motor) controlled by the CPU 26a, so that the four sub-detectors 331 to 334 described above are driven. The front of the radiation detection unit 2a is directed to the direction of incidence of the most radiation specified by the CPU 26a based on the count value.
The front of the radiation detection unit 2a is directed in the direction of incidence of the most radiation when the radiation detection unit 2a measures a dose or a dose rate that is equal to or higher than the set value. Do not change the direction. The reason is as follows. When measuring only relatively uniform and low-level radiation such as natural radioactivity, it is of course difficult to determine the direction of incidence of the most radiation because there is no fixed directionality. If it can be decided, it is likely to be unstable and constantly fluctuate. Therefore, in such a state, it is less necessary to change the direction of the radiation detection unit 2a to increase measurement accuracy, and it is more effective to avoid unstable movement of the radiation detection unit 2a.

  In addition, after the radiation dose or radiation dose rate measured by the radiation detection unit 2a reaches the set value or more and the front of the radiation detection unit 2a is directed to the most radiation incident direction by the direction switching unit 3, the radiation detection unit 2a It is desirable to shorten the counting time interval so as to acquire more detailed time variation data of the radiation dose or the radiation dose rate.

This embodiment relates to an environmental radiation management system in which a plurality of environmental dosimeters are distributed in a monitoring target area so that radiation emission locations can be specified.
FIG. 3 is a block diagram showing a configuration of this embodiment, and FIG. 4 is an explanatory diagram showing a method for specifying a radiation emission location in this embodiment.
In this embodiment, in order to enable communication between a plurality of environmental dosimeters-1 101 to environmental dosimeters-n 10n that can specify the incident direction of incident radiation, the data management device 5, and these environmental dosimeters. It comprises an infrared transmission / reception unit 4 connected to the data management device 5, and in particular, the data management device 5 is provided with position specifying means 51.
The environmental dosimeter-1 101 to the environmental dosimeter-n 10 have the same configuration as that shown in FIG. 1, and can specify the direction of incident radiation from the count value ratio of the sub-detector. .

The position specifying means 51 performs calculation processing for specifying the radiation emission location based on the installation location of each environmental dosimeter and the data of the respective radiation incidence directions received from each environmental dosimeter. It comprises a storage unit (memory) that stores a calculation program for specifying the installation location and position, a calculation unit (CPU) that executes the calculation program, and the like.
A method for specifying the position by the position specifying means 51 is shown in FIG. In Fig. 4, the installation location (P1 and P2) of each of the two environmental dosimeters (environmental dosimeter-1 and environmental dosimeter-2) is the starting point, along the direction of incidence of the most radiation of each of the environmental dosimeters. By finding the intersection (PX) of the two drawn straight lines (L1 and L2), the radiation emission location can be identified. If the coordinates of P1 and P2 and the slopes of the straight lines L1 and L2 are determined, PX can be easily calculated.
This system is operated to specify the radiation emission location, for example, when any one of a plurality of dispersed environmental dosimeters-1 101 etc. Is measured. The environmental dosimeter immediately transmits the measured value and the specified direction of incidence of the most radiation to the data management device 5, and the data management device 5 receiving this information immediately sends the respective doses or dose rates to the other environmental dosimeters. And the radiation incidence location is specified by the position specifying means 51 based on the information.

As a method of selecting an environmental dosimeter to be used for specifying the radiation emission location, naturally the one that measured the set value or more is selected, and only the next largest measured value is selected. A method of selecting the above, a method of selecting a value exceeding a predetermined reference value less than a set value, a method of selecting a value in the vicinity of a value measured above a set value, and the like are conceivable.
According to such an environmental radiation management system, it is possible to quickly and reliably grasp the radiation emission location.

The perspective view which shows the external appearance of the Example of the environmental dosimeter by this invention. The block diagram which shows the circuit structure of the Example of an environmental dosimeter. The block diagram which shows the structure of the Example of the environmental radiation management system by this invention. Explanatory drawing which shows the identification method of the radiation emission location in the Example of an environmental radiation management system. An example of the environmental dosimeter by a prior art is shown, (a) is a perspective view which shows the external appearance, (b) is a block diagram which shows the circuit structure.

Explanation of symbols

100, 100a Environmental dosimeter 1 Support part 2, 2a Radiation detection part
21 Front position 22 Display
23 Detection element + amplifier 24 Multiple discrimination circuits
25 Counting circuit 26, 26a CPU
27 Infrared transceiver circuit 28, 28a EEPROM
29, 29a Power supply circuit 3 Direction switching part
311 Sub detector-1 front position 312 Sub detector-2 front position
313 Sub detector-3 front position 314 Sub detector-4 front position
32 Turntable 321 Turntable drive
331 Direction-specific sub-detector-1 332 Direction-specific sub-detector-2
333 Direction identification sub-detector-3 334 Direction identification sub-detector-4
4 Infrared transceiver 5 Data management device
51 Positioning means

Claims (3)

A main radiation detector that measures the radiation dose and dose rate of the environment based on the output of the radiation detector;
A plurality of sub-radiation detectors arranged around the main radiation detection unit so as to have a high sensitivity to radiation coming from the front direction and different directions of the sensitive surfaces;
Direction switching means having a rotation mechanism capable of rotating the main radiation detection unit in a horizontal plane and arbitrarily setting the front position thereof;
When the radiation dose or the radiation dose rate measured by the main radiation detection unit reaches a set value or more, the respective radiation values of the plurality of sub-radiation detectors are compared and the largest amount of radiation comes. An arithmetic processing unit that specifies the most radiation incident direction and drives the rotation mechanism of the direction switching unit so that the front position of the main radiation detection unit faces the most radiation incidence direction,
An environmental radiation dose meter characterized by comprising: When the radiation dose or radiation dose rate measured by the main radiation detection unit reaches a set value or more and the front of the main radiation detection unit is directed in the direction of incidence of the most radiation by the direction switching unit, the main radiation detection unit 2. The environmental radiation dose meter according to claim 1, wherein the counting time interval is shortened to obtain more detailed time variation data of the radiation dose or the radiation dose rate. A radiation management system comprising: a plurality of environmental radiation dosemeters according to claim 1 arranged in a distributed manner; and a data management device that performs radiation management of an area to be monitored by communicating with them and collecting dose data. There,
Data management apparatus includes a position identification means consisting of an arithmetic unit storage unit having stored a calculation program for a specific location and a predetermined position of each environmental dosimeters,
If any of the environmental radiation dosimeters measures a radiation dose or dose rate that is greater than or equal to the set value, the environmental radiation dosimeter sends the dose data including the measured value and the specified maximum radiation incidence direction. , Immediately request other environmental radiation dosimeters to send their dose data,
Based on the dose data and said storage means information of location stored in the obtained from the environment dosimeter was to perform the calculation processing for identifying the radiation-emitting locations in the monitored area,
Environmental radiation management system characterized by

Images