JPH06324158A - Radiation monitoring device - Google Patents

Abstract

PURPOSE:To detect anomaly at early time by discriminating if the fine variation of the measurement value is generated by the measurement object (radioactive ray) or the anomaly in the characteristic variation on the device side. CONSTITUTION:The fundamental constitution is formed from a calculator 19 for calculating the statistical quantity of the detector signal (measurement value) and a multiple wave height analyzer 17 which carries out the spectrum measurement, and detects the abnormal variation of the measurement value, and at the same time, the soundness of the device is confirmed by measuring the change of the spectrum according to the prescribed sequence corresponding to the kind of the detector 1. Further, the constitution for adding a wave form observing device 18 is realized, and the existence of the anomaly of the signal itself is confirmed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation monitoring device for detecting radiation abnormality.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram showing a conventional radiation monitoring apparatus. In the figure, 1 is a radiation detector, 2 is a pre-amplifier, and 3 is a detector via a pre-amplifier 2. A main amplifier for amplifying a signal, 4 is a wave height discriminator for shaping and discriminating a detector signal passed through the amplifiers 2, 3 and 5 is a counter or rate meter for converting a signal train into a count value or a count rate. , 6 is a display for displaying a count value or a counting rate, 7 is a recorder for continuously recording the result, 8 is an alarm transmitter, 9 is a signal changeover switch, 10 is a test signal generator, 11 is a high voltage power supply. 1
Reference numeral 2 is a shutter drive circuit, 13 is a shutter arranged in the vicinity of the radiation detector 1, 14 is a radiation source for irradiating the radiation detector 1 with a predetermined radiation dose, and 15 is a measurement container (or pipe) for containing a fluid to be measured. ) And 16 are radioactivity contained in the fluid in the measurement container 15. The detector 1 is arranged outside the measurement container 15.

Next, the operation will be described. Measuring container 15
The radiation emitted from the radioactive substance 16 flowing inside is detected by the detector 1 arranged in the vicinity of the measurement container 15. The detection pulse signal enters the main amplifier 3 through the pre-amplifier 2 to be amplified, and the wave height discriminator 4 performs wave height discrimination / shaping, and the counter or rate meter 5 outputs the count value or count rate. It is converted into a counting signal. The counting result is displayed on the display 6 and simultaneously recorded continuously by the recorder 7. Also,
The count signal branched from the counter or rate meter 5 is
The alarm transmitter 8 compares the set value with the set value, and when the set value is exceeded, an alarm is sent to notify the operator of the abnormality of the monitoring target. Further, the shutter drive circuit 12 is operated to open the shutter 13 to irradiate the detector 1 with the radiation from the radiation source 14. The detector 1 detects the radiation of the radiation source 14, outputs a predetermined pulse signal, and displays a predetermined count value or count rate by the above-described operation processing. Thereby, the operator can confirm that the device is operating normally.

[0004]

Since the conventional radiation monitoring apparatus is constructed as described above, the alarm set value is fixed and the operator knows the abnormality by the result of simple comparison with the measured value. It will be. For this reason, there is a drawback that it is not possible to know a fluctuation abnormality in the period until reaching the alarm set value, that is, a minute fluctuation in radiation. Further, for the purpose of compensating for the above-mentioned drawback, it is also known that the abnormality of the change is known by inputting the measured value (counting signal) of the apparatus to another computer and calculating the rate of change of the measured value. However, there is a drawback in which it is not possible to distinguish whether the change in the measured value is due to the change in the radiation concentration, which is the original measurement target, or the change in the characteristics of the apparatus itself. Therefore, in order to identify the radiation abnormality, the abnormality is confirmed by separately performing radioactivity analysis of the fluid to be measured.

The present invention has been made in order to solve the above problems, and detects minute fluctuations in measured values, and whether the fluctuations are due to an increase in radiation or due to characteristic abnormalities on the device side. It is an object of the present invention to obtain a radiation monitoring device capable of identifying whether or not

[0006]

A radiation monitoring apparatus according to the present invention comprises radiation detecting means, and counting means (counter or rate meter 5) for measuring the count value or count rate of output pulse signals from this detecting means. A distribution signal measuring means (multiple wave height analyzing apparatus 17) for analyzing the peak value of the output pulse signal to measure a peak distribution signal, and a waveform measuring means for measuring the signal waveform of the output pulse signal (waveform observing apparatus 1
8) When compared to the normal state, if the count value or count rate fluctuates and the distribution signal and the signal waveform do not fluctuate, it is an abnormality due to an increase in radiation, and if there is a fluctuation in the distribution signal, the device side And an abnormal species discriminating means (computer 19) for discriminating that the abnormality is.

[0007]

In the radiation monitoring apparatus according to the present invention, the abnormal species discriminating means detects variations in the count value or counting rate, the distribution signal, and the waveform, and discriminates whether the radiation increase abnormality or the apparatus-side abnormality is based on this.

[0008]

【Example】

Example 1. The first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram of a radiation monitoring apparatus according to the present invention. The same components as those in the conventional example of FIG. In FIG. 1, 17 is a main amplifier 3
Multiple wave height analyzer for measuring the wave height distribution of the output signal pulse after passing through, 18 is a waveform observing device for measuring the signal pulse waveform, 19 is a count value of the counter, wave height distribution data from the multiple wave height discriminator 17, and waveform observing device 18 A computer for inputting the waveform data from the computer to perform arithmetic processing, 20 is a CRT, 21 is a printer, and 22 is a storage device for storing the arithmetic result.
Note that the radiation source 14 constantly irradiates the detector 1 with a predetermined amount of radiation.

Next, the operation will be described. Here, an embodiment using a plastic scintillation detector (hereinafter abbreviated as PL detector) as the detector 1 will be described. The PL detector usually detects radiation from the surrounding environment and outputs a pulse signal. This pulse signal is widened by the front widening device 2 and the main widening device 3, is wave-height discriminated by the wave height discriminator 4, and is converted into a count value (measured value 1) by the counter 5.
On the other hand, the pulse signal branched from the main amplifier 3 is input to the multiple wave height analyzer 17, and the wave height distribution signal (spectrum) is measured (measurement value 2). At the same time, the pulse signal is input to the oscilloscope as the waveform observing device 18, and the signal waveform is observed (measurement value 3). These measured values 1 to 3 are input to the calculator 19 and calculated according to the flow shown in FIG.

Now, when something abnormal occurs in the plant,
When a small amount of radioactive leakage occurs and a small amount of radioactive substance 16 flows into the fluid to be measured that enters the measurement container 15, the radiation signal from the radioactive substance 16 is counted through the same process as described above, and the measured value 1 is obtained. The count value of increases. Measured value 1
Is known to have a measured value fluctuation pattern different from the normal radiation fluctuation when there is an instruction rise, for example, by a known statistical process (whiteness test or the like) (step S1). Determine the fluctuation abnormality of. That is, the variation of the statistic is checked (step S2),
If there is a change in the statistics, there is a possibility of radiation abnormality, and if there is no change, there is no radiation abnormality. Next, the measured value 2
Calculates the reference peak position by the light pulser built in the PL detector (step S3), and confirms the deviation from the normal peak position of the spectrum stored in advance (step S4). If the peak position is in the predetermined normal position,
There is no drift (device abnormality caused by environmental changes, etc.) and it is judged to be normal. If there is a deviation from the predetermined position (this occurs when the environmental condition changes, such as when the gain setting of the device is changed), a "drift abnormality" warning message is transmitted. When there is no change in the peak position, the difference between the measured value 2 and the spectrum in the normal state (initial spectrum) in the predetermined energy region of the spectrum is calculated (step S5) and compared, and the presence or absence of spectrum fluctuation is confirmed (step S5). S6). When the characteristics of the PL detector deteriorate, the spectrum changes. Therefore, if there is a spectrum variation, a warning message of "detector abnormality" is transmitted. In addition, in parallel with step S3, the count value of the reference peak is calculated (step S3).
7) As a result of comparison with the initial value (step S8), if there is a difference from the count value, a warning message of "measurement system abnormality" is transmitted. If there is no difference between the count value and the initial value, that is, if it is normal, the waveform data of the measured value 3 is compared with the initial waveform data (step S9). Send an alarm message. When no change is observed in the signal waveform from the pre-amplifier 2 to the counter 5, the PL detector and the signal processing system are normal, and it is determined that "radiation increase (abnormal)" from the object to be measured. That is, the "radiation abnormality" is judged when the statistic of the measured value 1 varies, the measured value 2 is normal, and the measured value 3 does not change. This logical judgment is made by the AND circuit 30. Done. In summary, if the distribution signal fluctuates compared to the normal time, it is judged as an abnormality on the device side, and the count value or counting rate fluctuates compared to the normal time and the distribution signal and signal waveform fluctuate. If there is not, the computer 19 including the AND circuit 30 which determines that the abnormality is caused by the increase in radiation constitutes the abnormality type determination means.

Embodiment 2. Even if a rate meter is used in place of the counter 5 and the count rate as its output is used as the measured value 1, the same effect as in the first embodiment can be obtained.

Embodiment 3. In the first embodiment, the case where the PL detector is used as the detector 1 has been described. However, in the case where another type of detector, for example, the NaI detector (sodium iodide detector) is used, FIG. As shown, the resolution of the reference peak is calculated from the spectrum measurement result to confirm the presence or absence of detector deterioration, and to judge the soundness of the detector. That is, as shown in FIG. 3, step S4
After that, the resolution of the reference peak is calculated (step S1
0) to determine whether the resolution is abnormal (step S
11) If there is an abnormality, send out a "detector abnormality", and if there is no abnormality, it is determined that there is a possibility of radiation increase, and AND
The processing of the circuit 30 is awaited. Therefore, the processing 100 of steps S10 and S11 surrounded by a dotted line is different from that of the first embodiment.

Embodiment 4. Further, in the case of using a GM tube (Geigumula tube) as the detector 1, FIG.
As shown in (1), a peak search (step S12) is performed from the spectrum measurement result to confirm the presence or absence of an after-pulse peak other than the initial peak (step S1).
3) Determine the integrity of the detector. In the case of this embodiment,
After the determination of "detector abnormality", the determination of "drift abnormality" is performed. In addition, the count rate of the pulse of the wave height discrimination level (the level set to cut noise) or more is compared by the spectrum measurement value and the count signal (step S
14) If there is a difference in the counts, there is a possibility of radiation abnormality, and if there is no difference in the counts, it is determined as "measurement system abnormality" (step S15). That is, the process 200 surrounded by the broken line is different from the process of the example 1.2.

To briefly explain the gist of Examples 1 to 4, when the detector is a PL scintillation detector as a variation index of the distribution signal of the signal peak value, the peak height distribution in the low peak height distribution region and the NaI scintillation For a device using a detector, the detector resolution is used, and for a GM tube, the number of peaks is adopted.

Example 5. Further, if a pressure sensor is provided in the fluid to be measured and a temperature sensor is provided in the vicinity of the radiation detector so as to remove the fluctuation component of the count signal of the radiation detector due to the pressure change of the measurement fluid and the temperature change of the detector. Therefore, it is possible to more accurately confirm the presence or absence of radiation abnormality and equipment side abnormality. That is, as shown in FIG. 5, a pressure sensor 31 is added to the measurement container 15, and a temperature sensor 32 is added near the radiation detector 1. Then, these signals are input to the processing device 33. (Here, the signal processing device 33 includes devices after the front widening device 2 of FIG. 1, and performs the flow processing of FIGS. 2 to 4.) When the signal fluctuation of the detector 1 occurs there, Whether or not there is an abnormality is determined according to the flow described above, but the fluctuation of the count signal when there is an output a from the pressure sensor 31 and the temperature sensor 32 is not used as a material for the abnormality determination.

Example 6. In each of the above-described embodiments, the presence or absence of an abnormality is determined by the signal detected by one detector 1, but as shown in FIG.
Although it is in charge of the same radioactive leakage monitoring target (measurement vessel 15) as (corresponding to the detector 1), it outputs the signal of another detector B36 that detects the radiation in a different location of the vessel 15 and the output signal of the reactor 34. When a signal is input to the processing device 37 and a signal of the detector A35 fluctuates, whether or not there is an abnormality in the device is confirmed according to the above-described flow, and by comparing with the result of the abnormality determination of the output signal of the detector B36, It is possible to more appropriately discriminate whether the variation event is due to radiation or a change in device characteristics. That is, it is effective when the container 15 is long, and quick abnormality determination is possible, and more reliable abnormality determination can be performed because there are two detectors.

Embodiment 7. Further, as shown in FIG. 7, the reactor 34, the detector A35, and another process system B3 associated with the process system A38 to be monitored by the detector.
9 and a detector B36 attached to the reactor 9, and a plurality of plant information output from these reactors and detectors
By inputting into, and comparing each other, it is possible to monitor multiple process systems.

Example 8. In addition, the background radiation level of the environment surrounding the detector due to changes in reactor output is estimated,
If the influence on the instruction due to this is removed, it is possible to more accurately confirm whether or not there is an abnormality in measurement value fluctuation.

As described above, according to each of the above-described embodiments, the detection system and the detection system are detected by using the spectrum measurement and the abnormality determination flow corresponding to the type of the detector while obtaining the statistic of the detector signal (measurement value). Since the operation soundness of the measurement system can be confirmed, it is possible to confirm the presence or absence of radiation abnormality earlier than the abnormality detection by the alarm function of the conventional radiation monitoring device, and it is possible to help prevent the spread of accidents in the plant. Also,
The waveform observation device 18 measures the waveform of the detector signal,
By checking the presence of signals other than the detector, such as whether noise is superimposed, or the presence of an abnormality in the signal processing system, it is possible to confirm a disturbance abnormality from outside the measurement system.
Further, by combining other detectors with the furnace output signal as in the sixth embodiment, a more appropriate and accurate abnormality determination can be performed.

[0020]

As described above, according to the radiation monitoring apparatus of the present invention, the radiation detecting means, the output pulse signal counting means, the distribution signal measuring means, the waveform measuring means are compared with the normal state, An abnormal species discriminating means for discriminating that the distribution signal and the signal waveform are not changed and the distribution signal and the signal waveform are not changed, and the distribution signal is changed. Since it is equipped with, it is possible to detect a minute fluctuation in the measured value, and it is possible to determine whether the fluctuation is due to an increase in radiation or due to a characteristic abnormality on the device side, and an abnormality can be detected early. Further, according to the radiation monitoring apparatus of the present invention, the fluctuation of the count value due to the pressure fluctuation of the measurement fluid and the ambient temperature fluctuation of the detector is removed, or the count value and the reactor output at a plurality of parts are removed. By adopting a configuration in which the abnormality determination is performed by using, there is an effect that more accurate and reliable abnormality determination can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram of a radiation monitoring apparatus showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a signal processing flow according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a signal processing flow according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a signal processing flow according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a fifth embodiment of the present invention.

FIG. 6 is a block diagram showing a sixth embodiment of the present invention.

FIG. 7 is a block diagram showing a seventh embodiment of the present invention.

FIG. 8 is a block diagram showing an example of a conventional radiation monitoring apparatus.

[Explanation of symbols]

 1 Radiation Detector 5 Counter or Rate Meter (Counting Means) 17 Multiple Wave Height Analyzer (Distributed Signal Measuring Means) 18 Waveform Observing Equipment (Waveform Measuring Means) 19 Calculator (Abnormal Species Means)

Claims (7)

[Claims] 1. Radiation detection means, counting means for measuring the count value of the output pulse signal from the detection means, and distribution signal measuring means for analyzing the peak value of the output pulse signal to measure the peak distribution signal. A waveform measuring means for measuring the signal waveform of the output pulse signal, and a distribution signal and a signal waveform having no fluctuations in the count value as compared with the normal time, there is an abnormality due to radiation increase, and the distribution A radiation monitoring apparatus comprising: an abnormal species discriminating unit that discriminates an abnormality on the side of the apparatus when the signal fluctuates. 2. Radiation detecting means, counting means for measuring the counting rate of the output pulse signal from the detecting means, and distribution signal measuring means for analyzing the peak value of the output pulse signal to measure the peak distribution signal. , A waveform measuring means for measuring the signal waveform of the output pulse signal, and when there is no variation in the distribution signal and the signal waveform as compared to the normal state, the distribution signal and the signal waveform are abnormal, the distribution is A radiation monitoring apparatus comprising: an abnormal species discriminating unit that discriminates an abnormality on the side of the apparatus when the signal fluctuates. 3. The radiation detecting means is a plastic scintillation detector, the counting means for measuring the count value of the output pulse signal from the detecting means, and the peak value of the output pulse signal are analyzed to reduce the peak value as a peak distribution signal. Distribution signal measuring means for measuring the peak value distribution in the wave polymer region, waveform measuring means for measuring the signal waveform of the output pulse signal, and the distribution signal and the signal due to the fluctuation of the count value as compared with the normal time. A radiation monitoring apparatus comprising: an abnormality type determining unit that determines that there is an abnormality due to an increase in radiation when there is no fluctuation in the waveform, and an abnormality on the apparatus side when there is a fluctuation in the distribution signal. 4. The radiation detecting means is a sodium iodide detector, the counting means for measuring the count value of the output pulse signal from the detecting means, and the peak value of the output pulse signal are analyzed to obtain a peak distribution signal. The distribution signal measuring means for measuring the detector resolution, the waveform measuring means for measuring the signal waveform of the output pulse signal, and the fluctuation of the distribution signal and the signal waveform due to the fluctuation of the count value as compared with the normal time A radiation monitoring device comprising: an abnormality due to an increase in radiation when there is no radiation, and an abnormality type determination means for determining that there is an abnormality on the device side when there is a change in the distribution signal. 5. The radiation detecting means is a Gaigamuller tube, and counting means for measuring the count value of the output pulse signal from the detecting means, and the peak value of the output pulse signal are analyzed to determine the peak number as a peak distribution signal. Distribution signal measuring means for measuring, waveform measuring means for measuring the signal waveform of the output pulse signal, and radiation when there is no variation in the distribution signal and the signal waveform as compared with the normal time, when the count value varies. A radiation monitoring apparatus comprising: an abnormality due to an increase and an abnormality type determining unit that determines that the abnormality is on the apparatus side when the distribution signal changes. 6. The pressure detecting means for detecting the pressure of the fluid to be measured by the radiation detecting means, the temperature detecting means for detecting the ambient temperature of the radiation detector, and the temperature detecting means and the pressure detecting means. Means for removing a fluctuation component of the count value of the radiation detection means in accordance with the output of the radiation detection means from the count value measured by the radiation detection means. The radiation monitoring device according to item 4 or 5. 7. A plurality of the radiation detecting means are provided, and a reactor output detecting means for detecting an output of a nuclear reactor which supplies a measurement fluid to be measured by the radiation detecting means is provided, and the plurality of radiation detecting means are provided. A means for discriminating whether there is a radiation increase abnormality or an apparatus side abnormality based on the count value measured in step 1 and the reactor output measured by the reactor output detection means is added to the abnormal species discrimination means. The radiation monitoring apparatus according to item 1, item 3, item 4, item 4, or item 5.