JP4679862B2 - Radiation monitor - Google Patents

Description

  The present invention relates to a radiation monitor capable of performing various settings of a measurement unit remotely.

  The radiation monitor is installed for the purpose of measuring radiation in facilities such as nuclear power generation facilities, nuclear fuel cycle facilities, radiation utilization facilities, and the surrounding environment. In the above facilities, the area where the detection unit including the radiation detector of the radiation monitor is installed is almost always a radiation management area. In order to reduce exposure during inspection / adjustment, the measurement unit is installed away from the detection unit, for example, in the operation room.

  A conventional radiation monitor transmits an electric pulse signal detected by a radiation detector by connecting a detection unit and a measurement unit with a cable. However, since the electrical pulse signal is a minute signal, it may be affected by noise when the transmission distance is increased.

In order to solve the above problems, a method has been proposed in which an electric pulse signal is converted into a digital signal by a wave height discriminator, which is converted into an optical pulse signal and transmitted to a measurement unit through an optical cable. . The pulse height discriminator compares the crest value of the electric pulse signal detected by the radiation detector with the reference signal set in the crest discriminator, and outputs a digital pulse signal to the electric pulse signal having a crest value higher than the reference signal. Output. The digital pulse signal subjected to the pulse height discrimination process is converted into an optical pulse signal by the transmitter and transmitted to the measurement unit. The transmitted optical pulse signal is converted into a digital pulse signal by a receiver, and a count rate is obtained by a count rate meter provided in the measurement unit.
In this way, the counting rate of pulses of radiation with a predetermined energy or higher is measured. Further, the reference signal of the pulse height discriminator is transmitted as an optical pulse signal from the reference signal source, and the pulse height discrimination level can be set remotely (see, for example, Patent Document 1).
However, in order to set the wave height discrimination level, a check source must be set in the detector. Further, in order to manually set the wave height discrimination level based on the count rate, statistical fluctuations must be taken into account, and a long time is required for the setting.

  When measuring the surrounding environment of a facility, a method is adopted in which a detection unit and a measurement unit are installed inside a station building, and measurement data is transmitted to a monitoring center by a telemeter. In this case, the setting of the measurement unit must go to the station building each time, and the check source must be attached to the detection unit.

Japanese Patent Publication No. 6-27841

  In the conventional radiation monitor, when setting the wave height discrimination level from a remote location, the check radiation source must be set to the detector each time it is set, resulting in inefficiency and noise when the wave height discrimination level is lowered. There was a problem such as a decrease in tolerance for.

  An object of the present invention is to solve the above-described problems, and the object thereof is to change a set value other than the pulse height discrimination level by remote control, without taking time, and It is an object of the present invention to provide a radiation monitor that can perform various settings of a measurement unit without reducing tolerance for noise.

A radiation monitor according to the present invention includes a detection unit that converts a detection result of radiation detected by a radiation detector into an electric pulse signal, and a measurement device that measures radiation based on the electric pulse signal, and performs radiation measurement. A radiation monitor comprising a measurement unit having a means, a monitoring unit for remotely controlling the measurement unit, and a calibration radiation source irradiation means for irradiating the radiation detector with a calibration radiation source, the measurement unit comprising: Pulse height spectrum measuring means for measuring the pulse height spectrum of the electric pulse signal, control means for controlling the detection unit and equipment based on the control command from the monitoring unit, measurement results of the pulse height spectrum measuring means and the radiation measuring means, and the control command The monitoring unit processes the measurement result and remotely transmits the operation signal. The radiation detector is irradiated with the radiation source by the operation signal from the monitoring unit, and the measurement unit measures the wave height spectrum of the calibration source and the wave height spectrum data as the measurement result. Transmit to the monitoring unit, output the set value signal of the measurement unit remotely from the monitoring unit based on the wave height spectrum data, obtain the net count rate of any measurement range based on the wave height spectrum data, and change the measurement range Thus, the apparatus further includes a count rate comparison / calibration unit that automatically sets the measurement unit so that the net count rate matches the initial value stored in advance in the measurement unit .

According to the radiation monitor of the present invention, the pulse height spectrum of the electric pulse signal of the radiation detected by the radiation detector is measured, the pulse height spectrum data is transmitted to the monitoring unit as a digital signal, and the pulse height spectrum data and the initial value as a reference are measured. Therefore, the gain of the pulse amplifier or the high voltage supplied to the detector can be set remotely and efficiently.
In addition, since operation with a fixed wave height discrimination level becomes possible, the tolerance for noise does not decrease.
Further, when the radiation level is abnormal, the soundness of the detector can be easily confirmed remotely by comparing and analyzing the pulse height spectrum data and the initial value stored in advance.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding members and parts will be described with the same reference numerals.
Embodiment 1 FIG.
1 is a block diagram showing a radiation monitor according to Embodiment 1 of the present invention.
In FIG. 1, the radiation monitor includes a detection unit 31 for detecting radiation, a measurement unit 32 for operating the radiation measurement and detection unit 31, and a monitoring unit 33 for processing measurement data and controlling the measurement unit 32. I have.
The detection unit 31 includes a radiation detector 1 that detects radiation and outputs an analog signal pulse, a check radiation source 2 that irradiates the radiation detector 1 with radiation, and a shutter that shields the radiation detector 1 from the check radiation source 2. 3 is provided. Here, the check radiation source 2 and the shutter 3 constitute a check radiation source irradiating means that is a calibration radiation source irradiating means.

  The measurement unit 32 includes a high-voltage power supply 4 that supplies a high voltage to the radiation detector 1, a pulse amplifier 5 that amplifies the height of an analog signal pulse output from the radiation detector 1, and an analog signal amplified by the pulse amplifier 5. A pulse height discriminator 6 that outputs a digital signal pulse when the peak value of the pulse falls within a predetermined range, and a counter that counts the digital signal pulse output from the pulse height discriminator 6 and outputs count data 7 and an A / D converter 8 for peak-holding the peak value of the analog signal pulse amplified by the pulse amplifier 5 and outputting the peak value data.

In addition, the measurement unit 32 includes an arithmetic unit 9 that performs arithmetic processing on the above data, a memory 10 that stores the measurement data, and an electrical / optical signal converter 11 that transmits the measurement data to the monitoring unit 33.
The arithmetic unit 9 receives the count data output from the counter 7 and the crest value data output from the A / D converter 8 to perform arithmetic processing, and also receives an operation signal and a set value received from the monitoring unit 33 (described later). The detection unit 31 is operated based on the signal, and the high voltage setting of the high voltage power source 4, the gain setting of the pulse amplifier 5, and the wave height discrimination level of the wave height discriminator 6 are set.
The memory 10 also stores radiation measurement data, wave height spectrum data, high voltage set value data, gain set value data, and wave height discrimination level set value data received by the calculator 9 as processing results of the calculator 9.
The electrical / optical signal converter 11 converts radiation measurement data and pulse height spectrum data from a digital electrical signal to a digital optical signal and transmits the digital electrical signal to the monitoring unit 33, and also receives an operation signal and a set value signal received from the monitoring unit 33. Is converted from a digital optical signal to a digital electrical signal.

Here, the A / D converter 8, the calculator 9 and the memory 10 constitute a pulse height spectrum measuring means, and the wave height discriminator 6, the counter 7 and the calculator 9 constitute a radiation measuring means.
The computing unit 9 and the memory 10 constitute a control means.
The memory 10 stores in advance the initial value of the pulse height spectrum data.

The monitoring unit 33 includes an electrical / optical signal converter 12 that receives the measurement data, and a monitoring device 13 that processes the measurement data.
The electrical / optical signal converter 12 converts radiation measurement data and pulse height spectrum data received from the measurement unit 32 from a digital optical signal to a digital electrical signal, and converts an operation signal and a set value signal from the digital electrical signal to a digital optical signal. The data is converted and transmitted to the measurement unit 32.
Further, the monitoring device 13 compares the spectrum peaks of the pulse height spectrum data, which is the processing result of the computing unit 9, and the pulse height spectrum stored in the memory 10, and sets the measurement unit 32 so that the spectrum peaks match. Peak comparison / calibration means (not shown) is provided, and the transmitted radiation measurement data and pulse height spectrum data are inputted, calculated, analyzed, displayed, and the operation signal for operating the measurement unit 32 and peak comparison calibration. Based on the result of the means, a high voltage of the high voltage power source 4, a gain of the pulse amplifier 5, and a set value signal for setting the wave height discrimination level of the wave height discriminator 6 are output.
Here, the measurement unit 32 and the monitoring unit 33 are connected by an optical fiber 14 that transmits a digital optical signal bidirectionally.

FIG. 2 is a graph showing a pulse height spectrum when the radiation detector 1 is irradiated with the check radiation source 2 in the radiation monitor according to the first embodiment of the present invention.
In FIG. 2, the horizontal axis is a channel corresponding to the energy to be measured, and the vertical axis is the amount counted corresponding to the channel, that is, the count. a is the initial state of the spectrum peak unique to the radiation source, b is the state where the spectrum peak drifts to the lower side, and c is the state where the spectrum peak is drifted to the higher side. Here, the initial state of the spectrum peak is stored in advance in the memory 10 of the measurement unit 32, and the initial state and the measurement data are superimposed on the display screen of the monitoring device 13.

The operation of the radiation monitor having the above configuration will be described below.
The radiation detected by the radiation detector 1 is converted into an analog signal pulse having a peak value corresponding to the energy and output to the pulse amplifier 5, and the peak value is amplified by the pulse amplifier 5, and the pulse height discriminator 6 and A / It is output to the D converter 8. The analog signal pulse output to the pulse height discriminator 6 is discriminated from those having a peak value equal to or higher than the pulse height discrimination level, and is output to the counter 7 as a digital signal pulse.
Here, analog signal pulses having a crest value lower than the crest discrimination level are removed as noise. In addition, by providing the crest discrimination level at two locations, low and high, it is possible to discriminate and output analog signal pulses in a predetermined crest value range.
The digital signal pulse output from the pulse height discriminator 6 is counted by the counter 7, and the count data is converted into engineering values such as a count rate, a dose rate, and a concentration by the calculator 9 and output to the monitoring unit 33. The

The analog signal pulse output to the A / D converter 8 has a peak value measured, and the peak value data is associated with the channels arranged in the order of energy by the calculator 9 and is stored in the memory 10 as peak spectrum data. Stored in The pulse height spectrum data is extracted to the calculator 9 by an operation signal from the monitoring device 13 and transmitted to the monitoring unit 33.
Further, when an operation signal is transmitted from the monitoring device 13, the check line source irradiating means operates, the pulse height spectrum measuring means measures the pulse height spectrum, the pulse height spectrum data is transmitted to the monitoring unit 33, and the spectrum peak is analyzed. .

  In normal times, the pulse height spectrum is measured at a fixed period, but when the radiation level is abnormal, the above-mentioned fixed period pulse height spectrum data is automatically stored in the memory 10, and the pulse height spectrum data is obtained by requesting from the monitoring device 13. The cause investigation is supported by comparing and analyzing the wave height spectrum data transmitted to the monitoring unit 33 and stored in the memory 10.

Next, calibration of the radiation monitor will be described.
When the operation signal is transmitted from the monitoring device 13 to the measurement unit 32, the measurement unit 32 operates the check radiation source irradiation unit to open the shutter 3 and irradiate the radiation detector 1 with the check radiation source 2. The analog signal pulse of the check line source 2 detected by the radiation detector 1 is measured by the above operation, and the pulse height spectrum data is transmitted to the monitoring unit 33. The monitoring unit 33 compares the pulse height specific peak position of the pulse height spectrum data with the initial value, and if the deviation from the initial value is outside the allowable range, the monitoring device 13 sends a new high voltage to the computing unit 9. The set value data, gain set value data, and wave height discrimination level set value data are transmitted, and the calculator 9 sets the high voltage set value, gain set value, and wave height discrimination level set value again based on the updated data.

However, if the wave height discrimination level setting value is lowered, the tolerance to noise is lowered. Therefore, it is desirable to fix the wave height discrimination level and update the high voltage setting value and the gain setting value.
In addition, when the radiation detector 1 is a scintillation detector, the gain changes greatly when the high voltage setting is changed. Therefore, in the calibration every year, the coarse adjustment is performed with the high voltage setting of the high-voltage power supply 4, and the fine adjustment is performed with the pulse. It is desirable that the gain setting of the amplifier 5 is performed, and that the short-term inspection is operated with the gain setting of the pulse amplifier 5.

  Further, instead of the method of manually setting a new set value while viewing the current value and the initial value displayed on the display screen of the monitoring device 13, the wave height of the check source 2 is linked to the operation of the check source 2. The monitoring device 13 can calculate and automatically set the optimum gain based on the spectrum data.

According to the radiation monitor according to the first embodiment of the present invention, the check radiation source irradiating means and the pulse height spectrum measuring means are provided, so that the calibration by the gain of the pulse amplifier 5 or the high voltage of the radiation detector 1 becomes possible. Further, since the wave height discrimination level is not changed, calibration can be performed efficiently remotely without reducing the tolerance for noise.
Moreover, the health of the detector can be diagnosed from a remote location by comparing and analyzing the measurement data of the check line source irradiation wave height spectrum and the initial value.
Furthermore, the cause investigation can be supported by comparing and analyzing the periodic wave height spectrum data and the initial value of the wave height spectrum data stored in the memory 10 when the radiation level is abnormal.

  The electric / optical signal converter 11 and the electric / optical signal converter 12 are wireless communication devices that may transmit and receive radiation measurement data, pulse height spectrum data, operation signals, and set value signals as wireless digital signals. There is an effect.

Embodiment 2. FIG.
FIG. 3 is a block diagram showing a radiation monitor according to Embodiment 2 of the present invention.
In FIG. 3, the calibration radiation source irradiation means is an LED 15 that is a light pulse irradiation means and an LED driver 16 that controls the operation of the LED 15. Other configurations are the same as those of the first embodiment, and the description thereof is omitted.

FIG. 4 is a graph showing a pulse height spectrum when the radiation detector 1 is irradiated with a light pulse in the radiation monitor according to Embodiment 2 of the present invention.
In FIG. 4, d is a peak spectrum peak when the light pulse is irradiated, and e is a peak spectrum in a normal state. Here, the initial state of the spectrum peak is stored in advance in the memory 10 of the measurement unit 32, and the initial state and the measurement data are superimposed on the display screen of the monitoring device 13.

The operation of the radiation monitor having the above configuration will be described below.
When the operation signal is transmitted from the monitoring device 13 to the measurement unit 32, the measurement unit 32 operates the light pulse irradiation means, and the LED driver 16 operates the LED 15 based on the control signal from the calculator 9. The LED 15 generates a light pulse and irradiates the radiation detector 1. The analog signal pulse of the light pulse detected by the radiation detector 1 is measured by the above operation, and the pulse height spectrum data is transmitted to the monitoring unit 33.
The monitoring unit 33 performs the same comparison as in the first embodiment and transmits the set value data, and the computing unit 9 again calculates the high voltage set value, the gain set value, and the wave height discrimination level set value based on the received set value data. Set.
As the radiation detector 1, for example, a Si semiconductor detector that reacts to light in the same manner as radiation is used.

  According to the radiation monitor according to the second embodiment of the present invention, the check line source 2 and the shutter 3 are not required by providing the light pulse irradiation unit including the LED 15 and the LED driver 16 as the calibration source irradiation unit. Thus, the structure of the detection unit 31 is simplified, and the detection unit 31 can be reduced in size. In addition, the cost can be reduced and there is an effect that no radioactive waste is generated.

Embodiment 3 FIG.
FIG. 5 is a graph showing a wave height spectrum when the radiation detector is irradiated with the calibration radiation source in the radiation monitor according to the third embodiment of the present invention.
Here, the monitoring device 13 obtains a net count rate in an arbitrary measurement range based on the pulse height spectrum data, and changes the measurement range so that the net count rate matches the initial value stored in the measurement unit 32 in advance. Thus, a counting rate comparison calibration means (not shown) for automatically setting the measurement unit 32 is provided instead of the peak comparison calibration means.
Other configurations are the same as those in the first and second embodiments. The radiation detector 1 is a semiconductor detector, a plastic scintillation detector, or the like.

In FIG. 5, i is an initial spectrum stored in the memory 10 of the measurement unit 32, and j is the measurement data. When channels A to B are in the measurement range and the spectrum drifts from i to j, the integrated value of the count in the measurement range decreases.
Here, when the channel measurement range is shifted from AK to B-KB / A, the integrated value matches the initial value. Therefore, the radiation monitor can be calibrated by resetting the gain of the pulse amplifier 5 to 1-K / A.

Hereinafter, the automatic calibration procedure of the radiation monitor according to the third embodiment of the present invention will be described in more detail with reference to the flowchart of FIG.
First, for example, when a calibration start button is pressed on the monitoring device 13, normal spectrum measurement is executed (step S51).
Next, when the predetermined time T elapses, the check radiation source 2 is irradiated (step S52), and the spectrum measurement of the check radiation source 2 is executed (step S53).
Subsequently, when a predetermined time T elapses, the normal spectrum is subtracted from the count of the check source for each channel to obtain a net spectrum (step S54), and the net spectrum ch. A-ch. The count of B is integrated and a net count integrated value is calculated (step S55).
Then, net count rate = net count integrated value / T is calculated (step S56), and attenuation correction rate of check radiation source 2 = exp {0.693 × (elapsed time from test)} / (half-life)} Calculated (step S57).
Next, net count rate attenuation correction value = net count rate × attenuation correction rate is calculated (step S58). Here, if the net count rate attenuation correction value = the net count rate initial value (step S59), the calibration is terminated.

When the net count rate attenuation correction value <the net count rate initial value (step S60), the ch. AK-ch. The count of B-KB / A is integrated to calculate the net count integrated value (step S61). However, K is an integer of 1, 2, 3,..., And KB / A is an integer rounded down after the decimal point.
Next, net count rate = net count integrated value / T is calculated (step S62), and net count rate attenuation correction value = net count rate × attenuation correction rate is calculated (step S63). If net count rate attenuation correction value = net count rate initial value (step S64), new gain = gain initial value × (1−K / A) is calculated (step S65), and the calibration is terminated.

If the net count rate attenuation correction value <the net count rate initial value (step S60) is not satisfied, the ch. A + K to ch. The count of B + KB / A is integrated and a net count integrated value is calculated (step S66). However, K is an integer of 123,..., And KB / A is an integer rounded down after the decimal point.
Next, net count rate = net count integrated value / T is calculated (step S67), and net count rate attenuation correction value = net count rate × attenuation correction rate is calculated (step S68). When net count rate attenuation correction value = net count rate initial value (step S69), new gain = gain initial value × (1 + K / A) is calculated (step S70), and the calibration is terminated.

  According to the radiation monitor according to the third embodiment of the present invention, the net counting rate is obtained based on the pulse height spectrum data, and the measurement unit 32 is automatically set so that the measured value matches the initial value. The radiation monitor can be efficiently calibrated even for a detector in which the peak height peak does not appear.

Embodiment 4 FIG.
FIG. 7 is a block diagram showing a detection unit 31 of the radiation monitor according to Embodiment 4 of the present invention.
In FIG. 7, a detection unit 31 detects radiation and outputs an analog signal pulse, a radiation detector 1, a sample container 17 that discharges an inflow amount while securing a necessary volume of the sample to be measured, A lead shield 18 for shielding the sample container 17 and the radiation detector 1 from environmental radiation is provided.
About the structure of the measurement unit 32 and the monitoring unit 33, it is the same as that of Embodiment 1, The description is abbreviate | omitted.
In the case where the radiation detector 1 is, for example, a NaI scintillation detector, the natural radioisotope K-40 is contained in the glass of the NaI scintillator and photomultiplier tube constituting the radiation detector 1. Further, when the sample container 17 is made of a corrosion-resistant glass-reinforced FRP resin, K-40 is also included in the glass fiber.

FIG. 8 is a graph showing a pulse height spectrum in which a natural peak of a natural radioisotope K-40 appears in the radiation monitor according to Embodiment 3 of the present invention.
In FIG. 8, f indicates an initial state of the spectrum peak, g indicates a state where the spectrum peak drifts to the lower side, and h indicates a state where the spectrum peak drifts to the higher side. Here, the initial state of the spectrum peak is stored in advance in the memory 10 of the measurement unit 32, and the initial state and the measurement data are superimposed on the display screen of the monitoring device 13.

The operation of the radiation monitor having the above configuration will be described below.
The K-40 analog signal pulse detected by the radiation detector 1 is measured by the above operation, and the pulse height spectrum data is transmitted to the monitoring unit 33. The monitoring unit 33 performs the same comparison as in the first embodiment and transmits the set value data, and the computing unit 9 again calculates the high voltage set value, the gain set value, and the wave height discrimination level set value based on the received set value data. Set.

  In addition, when using natural radioisotope K-40, since the peak count rate is small, in order to measure a spectrum peak correctly, long-time measurement is required. When the sample container 17 is made of stainless steel or the like, it does not contain the natural radioisotope K-40, so that the measurement needs to be further prolonged. Therefore, for example, the data is analyzed by setting the pulse height spectrum measurement at a regular period of normal time as one day.

  According to the radiation monitor according to the fourth embodiment of the present invention, the radiation detector 1 detects K-40, which is a natural radioisotope, instead of the check radiation source irradiation means, thereby irradiating the calibration radiation source. Since no means is required and the structure of the detection unit 31 is simplified, the detection unit 31 can be reduced in size. Therefore, the cost can be reduced and the effect that no radioactive waste is generated is achieved.

Embodiment 5. FIG.
FIG. 9 is a block diagram showing a detection unit 31 of the radiation monitor according to Embodiment 5 of the present invention.
In FIG. 9, the detection unit 31 includes a radiation detector 1 that detects radiation and outputs an analog signal pulse, and a protective case 19 that protects the radiation detector 1 from direct sunlight, wind and rain, and the like.
Further, the station building 20 stores the detection unit 31 and the measurement unit 32 separately from the environment. Here, the radiation detector 1 is attached to the ceiling or the like of the office building 20 to detect environmental space γ rays.
About the structure of the measurement unit 32 and the monitoring unit 33, it is the same as that of Embodiment 1, The description is abbreviate | omitted.

FIG. 10 is a block diagram showing the dose rate calculation means in the measurement unit 32 of the radiation monitor according to Embodiment 5 of the present invention.
In FIG. 10, the dose rate calculation means is provided in the calculator 9, a pulse value / dose converter 21 for inputting the pulse wave height data of the A / D converter 8 and performing dose weighting calculation, and the dose. And a dose rate calculation unit 22 that calculates the dose rate by integrating and dividing the integrated dose by the integration time.

The operation of the radiation monitor having the above configuration will be described below.
Dose rate data, which is the calculation result of the dose rate calculation means, is transmitted from the station building 20 to the monitoring unit 33 by a telemeter together with the wave height spectrum data.
Since the natural radioisotope K-40 is contained in the soil, concrete, etc. around the station building 20, the monitoring device 13 monitors the fluctuation of the spectrum peak using the intrinsic spectrum peak of K-40 as an index. If it fluctuates, the radiation monitor is calibrated by adjusting the spectrum peak remotely.
The γ-rays radiated by the Radon-Tron daughter nuclide contained in the rain have energy higher than the K-40 γ-ray 1461 keV, and this shifts the apparent peak. The same is true for artificial nuclides. Therefore, when the radiation indication value is increasing, the measurement data is not taken in and discarded.
Instead of manually setting a new setting value while looking at the current value and the initial value displayed on the display screen of the monitoring device 13, the monitoring device 13 periodically sucks K-40 peak height peak data. The appropriate gain or high voltage can be analyzed and the set value can be automatically updated.

According to the radiation monitor according to the fifth embodiment of the present invention, in the radiation monitor for monitoring the environment around the facility, the spectrum peak of the natural radioisotope K-40 is used as the index peak, and this is remotely monitored and calibrated. Accordingly, it is unnecessary to periodically go around the station 20 for the calibration of the index peak, and there is an effect that the maintenance becomes easy.
Further, instead of the method of manually setting a new set value while looking at the current value and the initial value displayed on the display screen of the monitoring device 13, the monitoring device 13 automatically and periodically picks up the peak spectrum peak and calibrates it. By performing the above, long-term drift of the radiation detector 1 can be suppressed, and environmental radiation can be measured with high accuracy.

It is a block diagram which shows the radiation monitor which concerns on Embodiment 1 of this invention. It is a graph which shows the pulse height spectrum at the time of irradiating a check radiation source to the radiation detector of the radiation monitor which concerns on Embodiment 1 of this invention. It is a block diagram which shows the radiation monitor which concerns on Embodiment 2 of this invention. It is a graph which shows the wave height spectrum at the time of irradiating an optical pulse to the radiation detector of the radiation monitor which concerns on Embodiment 2 of this invention. It is a graph which shows the wave height spectrum at the time of irradiating the radiation source to the radiation detector of the radiation monitor which concerns on Embodiment 1 of this invention. It is a flowchart which shows the automatic calibration procedure of the radiation monitor which concerns on Embodiment 1 of this invention. It is a block diagram which shows the detection unit of the radiation monitor which concerns on Embodiment 3 of this invention. It is a graph which shows the wave height spectrum where the natural peak of the natural radioisotope K-40 appeared in the radiation monitor concerning Embodiment 3 of this invention. It is a block diagram which shows the detection unit of the radiation monitor which concerns on Embodiment 4 of this invention. It is a block diagram which shows the dose rate calculating means in the measurement unit of the radiation monitor which concerns on Embodiment 4 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Radiation detector, 2 Check radiation source, 3 Shutter, 4 High voltage power supply, 5 Pulse amplifier, 6 Wave height discriminator, 7 Counter, 8 A / D converter, 9 Calculator, 10 Memory, 11, 12 Electricity / light Signal converter, 13 Monitoring device, 14 Optical fiber, 15 LED, 16 LED driver, 17 Sample container, 18 Lead shield, 19 Protective case, 20 Local building, 21 Crest / dose conversion unit, 22 Dose rate calculation unit, 31 Detection unit, 32 measurement unit, 33 monitoring unit.

Claims (3)

A detection unit that converts the detection result of the radiation detected by the radiation detector into an electrical pulse signal;
A measurement unit including a device for measuring, measuring the radiation based on the electrical pulse signal, and having radiation measurement means;
A monitoring unit for remotely controlling the measurement unit;
A radiation monitor comprising: a calibration radiation source irradiating means for irradiating the radiation detector with a calibration radiation source;
The measurement unit includes a pulse height spectrum measuring unit that measures a pulse height spectrum of the electric pulse signal, a control unit that controls the detection unit and the device based on a control command from the monitoring unit, and a pulse height spectrum measuring unit; Storage means for storing the measurement result of the radiation measurement means and the control command;
The monitoring unit has monitoring means for processing the measurement result and outputting an operation signal remotely.
Irradiating the radiation detector with the calibration radiation source by the operation signal from the monitoring unit;
The measurement unit measures the wave height spectrum of the calibration source, and transmits the wave height spectrum data as a measurement result to the monitoring unit.
Output the set value signal of the measurement unit remotely from the monitoring unit based on the wave height spectrum data ,
The measurement unit obtains a net count rate in an arbitrary measurement range based on the wave height spectrum data, and changes the measurement range so that the net count rate matches an initial value stored in advance in the measurement unit. A radiation monitor characterized by further comprising a counting rate comparison / calibration means for automatically setting the above .   2. The radiation monitor according to claim 1, wherein the calibration radiation source irradiating means includes a check radiation source irradiating means for irradiating the radiation detector with a check radiation source.   The radiation monitor according to claim 1, wherein the calibration radiation source irradiation unit includes a light pulse irradiation unit configured to irradiate the radiation detector with a light pulse.

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