JP2013072828A - Radiation measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device which determines the deterioration state of a radiation detector.SOLUTION: A GM counter 10 is attached with an RF tag 12 in which an identifier (ID) of the GM counter 10 is stored. The RF tag 12 also stores data on a manufacturing date of the GM counter. A reader 50 reads data on the ID and the manufacturing date which is transmitted from the RF tag 12 and outputs the acquired data to a control part 30. The control part 30 identifies the GM counter corresponding to the ID based on the data on the ID. The control part 30 further determines the deterioration state of the identified GM counter 10 based on history information of the identified GM counter. The control part 30 displays a warning of deterioration on a display 40 when the GM counter 10 has been determined to be deteriorated. History information of a GM counter is a manufacturing date, an integrated value of counts, and an integrated value of measuring time, and is stored in a memory 60.

Description

  The present invention relates to a radiation measuring apparatus that determines a deterioration state of a radiation detector.

  There is known a radiation measuring apparatus that detects radiation with a radiation detector, calculates a measured value of radiation from a detection signal obtained thereby, and displays the measured value. In order to accurately measure radiation over a long period using a radiation measuring apparatus, it is desirable to be able to grasp the state of deterioration of the radiation measuring apparatus, in particular, the state of aging deterioration of the radiation detector. For example, Patent Document 1 proposes a technique for detecting deterioration of a semiconductor detector.

  As radiation detectors, in addition to semiconductor detectors, detectors such as GM counters and ionization chambers are well known. In particular, in the GM counter, since organic gas or the like sealed inside for detecting radiation deteriorates with the detection of radiation over a long period of time, it is desirable that the state of deterioration can be accurately grasped.

JP 2002-131439 A

  In view of the background art described above, the inventor of the present application has repeatedly researched and developed a technique for grasping the state of deterioration of the radiation detector.

  The present invention has been made in the course of research and development, and an object of the present invention is to provide an apparatus for determining the deterioration state of a radiation detector such as a GM counter.

  A suitable radiation measurement apparatus that meets the above-described object includes a radiation measurement unit that obtains a measurement value of radiation based on a detection signal obtained from a radiation detector, and radiation based on identification information individually assigned to each radiation detector. A detector specifying unit for specifying a detector, a deterioration determining unit for determining a deterioration state of the radiation detector based on the history information of the specified radiation detector, and the deterioration when the radiation detector is deteriorated And a deterioration warning unit that issues a warning indicating the above.

  In the above configuration, the radiation detector is, for example, an ionization chamber, a proportional counter, a GM counter, or the like. Moreover, the identification information provided for every radiation detector is memorize | stored in RF tag with which a radiation detector is equipped, a memory, a barcode, etc., for example, and is provided to a detector specific part as needed. Further, the history information of the radiation detector is information indicating, for example, a use state from the manufacture of the radiation detector to the present. In addition, a warning indicating deterioration is transmitted to the user by, for example, display or sound. According to the above configuration, when the radiation detector is deteriorated, a warning indicating the deterioration is issued. For example, before the radiation detector breaks down, it is possible to take measures such as maintenance or replacement of the radiation detector. It becomes possible, and it becomes possible to reduce or avoid an erroneous measurement caused by a failure.

  In a preferred embodiment, the radiation detector is a GM counter, and the radiation measurement unit calculates the measurement value based on a counting result of radiation counted using the GM counter, and the history information Includes an integrated value of the counting results obtained so far using the GM counter, and the deterioration determination unit determines whether the GM counter is based on the integrated value of the counting results related to the GM counter. The deterioration state is determined.

  In a preferred specific example, the history information includes manufacturing date information of the GM counter, and the deterioration determination unit is based on an integrated value of a counting result regarding the GM counter and manufacturing date information of the GM counter. Then, the deterioration state of the GM counter is determined.

  In a desirable specific example, it further has a plateau measurement part which measures the plateau of the GM counter based on the correspondence between the voltage applied to the GM counter and the count result obtained using the GM counter. The deterioration determination unit determines the deterioration state of the GM counter based on the integrated value of the count result regarding the GM counter, the manufacturing date information of the GM counter, and the measurement result of the plateau regarding the GM counter. It is characterized by determining.

  In a desirable specific example, the deterioration determining unit is at least one of a condition that an integrated value of count results relating to the GM counter tube is equal to or greater than a threshold value and a condition that an elapsed time from the date of manufacture of the GM counter tube is equal to or greater than a threshold value. Is satisfied, and the plateau measurement result regarding the GM counter tube is abnormal, it is determined that the GM counter tube is deteriorated.

  The present invention provides an apparatus for determining the deterioration state of a radiation detector such as a GM counter. For example, according to a preferred aspect of the present invention, when the radiation detector is deteriorated, a warning indicating the deterioration is issued, so that the radiation detector is maintained or replaced before the radiation detector breaks down. Thus, it is possible to reduce or avoid erroneous measurement associated with a failure.

It is a figure which shows the suitable radiation measuring device in implementation of this invention. It is a figure which shows the career information table memorize | stored in memory. It is a figure for demonstrating the specific example of the deterioration determination based on the integrated value of a count. It is a figure for demonstrating the specific example of the deterioration determination based on a manufacturing date. It is a flowchart for demonstrating operation | movement of the radiation measuring device of FIG.

  FIG. 1 is a view showing a radiation measuring apparatus suitable for carrying out the present invention. The radiation measuring apparatus shown in FIG. 1 is, for example, a survey meter, and includes a GM counter tube (Geiger-Muller counter tube) 10 and an apparatus main body 100. The GM counter tube 10 is connected to the apparatus main body 100 via a cable (not shown). The GM counter tube 10 and the cable are preferably configured to be removable from the apparatus main body 100.

  The GM counter tube 10 is filled with a gas such as an organic gas, and includes an electrode pair that applies a voltage of about several hundred volts to the gas. Then, cations and electrons generated in the gas by the incidence of radiation are captured by the electrode pair to generate an electrical pulse signal, and the number of pulse signals corresponding to the detected amount of radiation (number of radiation particles) Is output from the GM counter 10.

  The counting unit 20 in the apparatus main body 100 counts the number of pulse signals output from the GM counter tube 10. Note that an amplifier or the like may be provided in front of the counting unit 20, and a weak pulse signal output from the GM counter tube 10 may be amplified by an amplifier or the like before being provided to the counting unit 20. The counting unit 20 outputs the counting result to the control unit 30.

  The control unit 30 controls each unit in the radiation measurement apparatus of FIG. 1 and also executes a process of calculating a measurement value of radiation. That is, the control unit 30 calculates, for example, a count rate that is a count per unit time (1 minute or 1 second), a measurement value obtained from the count rate, or the like based on the count result obtained from the count unit 20. To do. Then, the calculated measurement value is displayed on the display unit 40.

  In the radiation measurement apparatus of FIG. 1, an RF tag 12 is attached to the GM counter tube 10. The RF tag 12 stores an identifier (ID) of the GM counter tube 10. That is, an identifier is individually assigned to each of the plurality of GM counters 10, and the identifier of the GM counter 10 to which the RF tag 12 is attached is stored in the RF tag 12. The RF tag 12 also stores the date of manufacture date of the GM counter tube 10 to which the RF tag 12 is attached. The identifier and date of manufacture data stored in the RF tag 12 are transmitted by radio waves.

  The reader 50 in the apparatus main body 100 reads the identifier and manufacturing date data transmitted from the RF tag 12, and outputs the read data to the control unit 30. Based on the identifier data, the control unit 30 identifies the GM counter 10 corresponding to the identifier. Thereby, the GM counter tube 10 connected to the apparatus main body 100 among the plurality of GM counter tubes 10 is specified.

  The radiation measurement apparatus of FIG. 1 determines the deterioration state of the GM counter 10 based on the history information regarding the identified GM counter 10, and indicates the deterioration when the GM counter 10 is deteriorated. A warning is displayed on the display unit 40. The history information regarding the GM counter tube 10 includes the date of manufacture, the integrated value of the count, the integrated value of the measurement time, and the like, and is stored in the memory 60.

  Therefore, determination of the deterioration state of the GM counter tube 10 in the radiation measurement apparatus of FIG. 1 will be described below. In addition, about the part (structure) shown in FIG. 1, the code | symbol of FIG. 1 is utilized in the following description.

  FIG. 2 is a diagram showing a history information table stored in the memory 60. The history information table includes an identifier for each of the plurality of GM counters 10, that is, a GM counter ID, a manufacturing date, a count integrated value, and a measurement time regarding the GM counter 10 corresponding to the GM counter ID. It is the table which matched the integrated value.

  The integrated value of the count is the cumulative number of pulse signals that have been detected and output since the GM counter 10 was manufactured. The integrated value of the measurement time is the same as that after the GM counter 10 was manufactured. This is the cumulative measurement time during which the radiation was detected.

  The control unit 30 reads history information corresponding to the identifier (GM counter ID) read through the GM counter 10 connected to the apparatus main body 100, that is, the reader 50, from the memory 60, and the integrated value of the count and measurement time The deterioration of the GM counter 10 is determined based on the date of manufacture.

  FIG. 3 is a diagram for explaining a specific example of the deterioration determination based on the integrated value of the count. FIG. 3 shows a graph of a specific GM counter tube 10 in which the horizontal axis is the time axis and the vertical axis is the integrated count value. The graph shows that the integrated value of the count gradually increases as the measurement of radiation is repeated, that is, as time passes. The exchange encouragement threshold value THer and the exchange request threshold value THed are set based on, for example, statistical data or theoretical values.

  When the integrated value of the count reaches the replacement encouragement threshold THEr, the control unit 30 determines that the GM counter tube 10 should be replaced or maintained, and controls the display unit 40 to replace the user with the user. Etc. is displayed. Furthermore, when the integrated value of the count reaches the replacement request threshold value THed, the control unit 30 determines that the GM counter tube 10 should be replaced or maintained, and controls the display unit 40 to Display to indicate that replacement is required. When the replacement request threshold value THed is reached, processing such as limiting the measurement of radiation by the GM counter tube 10 may be executed as necessary.

  The user replaces or maintains the GM counter tube 10 within the replacement grace period from when the integrated value of the count reaches the replacement encouragement threshold value THer until reaching the replacement request threshold value THed.

  The control unit 30 may perform the deterioration determination using the integrated value of the measurement time instead of the integrated value of the count. That is, the control unit 30 determines that it is better to replace or maintain the GM counter tube 10 when the measurement value integrated value reaches the measurement time replacement encouragement threshold. When the replacement request threshold is reached, it may be determined that the GM counter 10 should be replaced or maintained. Moreover, the control part 30 may determine deterioration based on a manufacturing date so that it may demonstrate below.

  FIG. 4 is a diagram for explaining a specific example of deterioration determination based on the date of manufacture. FIG. 4 shows a graph of the time variation of the non-defective product rate regarding the GM counter tube 10 obtained from the life estimation model of the GM counter tube 10. The horizontal axis of the graph is the time (manufacturing elapsed time) from the date of manufacture, and the vertical axis of the graph is the non-defective product rate (percentage) indicating the proportion of non-defective products. The graph shows how the yield rate gradually decreases as time passes from the date of manufacture. The life warning threshold THlr and the life reaching threshold THld are set based on, for example, statistical data or theoretical values.

  The control unit 30 determines that the life of the GM counter tube 10 is approaching when the manufacturing elapsed time reaches the time corresponding to the life notice threshold THlr, and controls the display unit 40 to notify the user. On the other hand, a display indicating that the lifetime is approaching is performed. Furthermore, the control unit 30 determines that the GM counter tube 10 has reached the end of life when the elapsed manufacturing time has reached the time corresponding to the life threshold value THld, and controls the display unit 40 to A message indicating that the product has reached the end of its life is displayed. When the time point corresponding to the lifetime reaching threshold THld is reached, processing such as limiting the measurement of radiation by the GM counter 10 may be performed as necessary. The user replaces the GM counter tube 10 within the replacement grace period.

  FIG. 5 is a flowchart for explaining the operation of the radiation measuring apparatus of FIG. First, prior to the measurement of radiation, the identifier and the date of manufacture are read from the RF tag 12 of the GM counter tube 10, and the GM counter tube 10 is specified based on the identifier (S501). In the case of the GM counter 10 used for the first time in this apparatus, the identifier (GM counter ID) and the date of manufacture of the GM counter 10 are added to the history information table (FIG. 2).

  When the measurement of radiation by the specified GM counter 10 is started and the amount of radiation (number of radiation particles) is counted (S502), the count result is added to the integrated value of the GM counter 10. (S503). That is, the count result is added to the integrated value (FIG. 2) of the count related to the GM counter tube 10 stored in the memory 60 as needed. The measurement time is added to the integrated value of the measurement time (FIG. 2) for the GM counter tube 10 as needed.

  Thus, the processing of S502 and S503 is repeated until the measurement of radiation is completed. When the measurement of radiation is completed (S504), the integrated value is compared with the threshold value (S505). For example, if the integrated value of the count is smaller than the replacement encouragement threshold value THer (FIG. 3), it is determined that replacement or maintenance of the GM counter tube 10 is unnecessary, and the manufacturing elapsed time is compared with the threshold value (S506). If the elapsed manufacturing time has not reached the time point corresponding to the lifetime notice threshold THlr (FIG. 4), it is determined that there is no problem in the lifetime of the GM counter tube 10, and this flowchart is ended.

  On the other hand, in S505, for example, when the integrated value of the count is equal to or greater than the exchange encouragement threshold value THer, or in S506, for example, when the manufacturing elapsed time has reached the time corresponding to the life warning threshold value THlr, the plateau measurement of the GM counter tube 10 is performed. Implemented (S507).

  In the plateau measurement, the GM counter tube 10 is irradiated with a certain intensity of radiation, the applied voltage to the GM counter tube 10 is changed, and there is a correspondence between each applied voltage and the count rate measured by the applied voltage. Measured. Then, a plateau (a constant counting area), which is a section of the applied voltage in which the count rate hardly changes even when the applied voltage changes, is confirmed.

  Further, based on the result of the plateau measurement, it is determined whether or not the plateau is normal (S508). For example, whether or not the plateau is normal is determined based on the inclination of the plateau (the rate of change in the count rate accompanying the change in the applied voltage), the length of the plateau (the range of the applied voltage that can be regarded as a plateau), and the like.

  If the plateau is normal, it is determined that replacement of the GM counter tube 10 or the like is unnecessary, and this flowchart ends. On the other hand, if the plateau is abnormal, a warning that the replacement or maintenance of the GM counter 10 is recommended or that the life of the GM counter 10 is approaching is displayed (S509). finish.

  In S505, for example, when the integrated value of the count is equal to or greater than the replacement request threshold THed (FIG. 3), or in S506, for example, when the manufacturing elapsed time has reached a time corresponding to the life reaching threshold THld (FIG. 4). The plateau measurement (S507) and plateau determination (S508) are omitted, and a warning that the GM counter 10 should be replaced or maintained or that the GM counter 10 has reached the end of its life is displayed. (S509).

  Further, when the same GM counter tube 10 is used in a plurality of apparatus main bodies 100, a configuration in which the contents of the history information table (FIG. 2) can be mutually referred between the plurality of apparatus main bodies 100 is desirable. Then, the integrated values (counted values or the integrated values of the measurement times) related to the same GM counter tube 10 managed in each of the plurality of apparatus main bodies 100 are added to obtain a true integrated value regarding the GM counter tube 10.

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above is only a mere illustration in all the points, and does not limit the scope of the present invention. The present invention includes various modifications without departing from the essence thereof.

  10 GM counter tube, 12 RF tag, 20 counting unit, 30 control unit, 40 display unit, 50 reader, 60 memory, 100 device main body.

Claims (5)

A radiation measurement unit for obtaining a measurement value of radiation based on a detection signal obtained from the radiation detector;
A detector identifying unit that identifies a radiation detector based on identification information individually assigned to each radiation detector;
A degradation determination unit that determines the degradation state of the radiation detector based on the history information of the identified radiation detector;
A deterioration warning unit that issues a warning indicating that the radiation detector has deteriorated, and
Having
A radiation measuring apparatus characterized by that. The radiation measurement apparatus according to claim 1,
The radiation detector is a GM counter;
The radiation measurement unit calculates the measurement value based on a counting result of radiation counted using a GM counter;
The career information includes an integrated value of count results obtained so far using a GM counter,
The deterioration determination unit determines a deterioration state of the GM counter based on an integrated value of a count result related to the GM counter.
A radiation measuring apparatus characterized by that. The radiation measurement apparatus according to claim 2,
The career information includes manufacturing date information of the GM counter,
The deterioration determination unit determines the deterioration state of the GM counter based on the integrated value of the count result related to the GM counter and the manufacturing date information of the GM counter.
A radiation measuring apparatus characterized by that. The radiation measurement apparatus according to claim 2 or 3,
A plateau measurement unit that measures the plateau of the GM counter based on the correspondence between the voltage applied to the GM counter and the count result obtained using the GM counter;
The deterioration determination unit determines the deterioration state of the GM counter based on the integrated value of the count result regarding the GM counter, the manufacturing date information of the GM counter, and the measurement result of the plateau regarding the GM counter. judge,
A radiation measuring apparatus characterized by that. The radiation measurement apparatus according to claim 4,
The deterioration determination unit satisfies at least one of a condition that an integrated value of count results relating to the GM counter tube is equal to or greater than a threshold value and a condition that an elapsed time from the date of manufacture of the GM counter tube is equal to or greater than a threshold value, And when the measurement result of the plateau relating to the GM counter is abnormal, it is determined that the GM counter is deteriorated.
A radiation measuring apparatus characterized by that.

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