JPH0527040A - Radiation ray measuring device - Google Patents

Abstract

PURPOSE:To obtain a radiation ray measuring device which permits the early detection of the anomaly of a detector and the removal of the electrode produced substances without interrupting the common radiation ray quantity measurement. CONSTITUTION:A radiation ray detector 1 radiates radiation rays onto the electric field formed by applying a constant voltage between electrodes and detects the electric current which flows between the electrodes. A variable voltage applying device 2 applies the voltage which varies periodically so that the constant voltage and the voltage higher by a prescribed value than the constant voltage are included in the instantaneous value, between the electrodes. An electric current read-out device 4 periodically reads out the electric currents of the electrode which correspond to a plurality of voltage values including the constant voltage and the higher voltage. A judging device 5 judges the radiation ray quantity from the read-out electric current value for the constant voltage and detects the anomaly of the radiation ray detector 1 from the read- out electric current value for the voltage other than the constant voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation measuring device,
In particular, it relates to self-diagnosis for detecting an abnormality in the device itself.

[0002]

2. Description of the Related Art There are radiation detectors that radiate an electric field formed by applying a constant voltage between electrodes and detect a current flowing through the electrodes. Since the current output of such a radiation detector depends on the voltage applied to the electrodes, it is necessary to supply a stable constant voltage.

Incidentally, in a fission chamber for measuring neutrons in a nuclear reactor, a voltage obtained from a stable DC power source of 100 [V] is applied to a radiation detector to obtain a current signal proportional to the amount of neutrons.

In this case, the current signal does not change only according to the radiation dose, but is also affected by the voltage and the pressure of the enclosed gas. Therefore, in order to confirm the soundness of the detector, or to investigate the cause of the abnormality when the detector output is abnormal, the output characteristics with respect to the applied voltage (from 0 [V] to 300 [V] in the ionization chamber) The voltage is changed to some extent and the output change) is measured.

[0005]

The above-mentioned voltage-output characteristic measurement is generally performed by suspending normal measurement. Therefore, in a reactor power range monitor composed of hundreds of neutron detectors, the detectors to be measured had to be temporarily removed from the monitoring of the reactor power and the output characteristics had to be measured. For this reason, the output characteristic measurement is limited to the occurrence of an abnormality or the periodic inspection, and there is a problem that the abnormality of the detector cannot be detected early.

Further, in this type of radiation detector in which a voltage of about 100 [V] is applied between the electrodes, protrusions may be generated on the electrodes, and interelectrode discharge may occur via the protrusions. There is a method of applying a voltage considerably higher than the normal voltage to remove the protrusions, but there is also a problem that the normal measurement must be interrupted at regular intervals.

The present invention has been made to solve the above problems, and provides a radiation measuring apparatus which enables early detection of detector abnormality and removal of electrode products without interrupting normal measurement. The purpose is to

[0008]

SUMMARY OF THE INVENTION The present invention provides a radiation detector for radiating an electric field formed by applying a constant voltage between electrodes and detecting a current flowing through the electrodes, the constant voltage and the radiation detector. A variable voltage applying device that applies a voltage that cyclically changes so as to include a high voltage higher than a predetermined value in each instantaneous value, and a plurality of voltage values including at least the constant voltage and the high voltage. And a current reading device that periodically reads the current of the electrode, measures the radiation dose from the read current value for the constant voltage, and detects an abnormality of the radiation detector from the read current value for voltages other than the constant voltage. To do.

[0009]

According to the present invention, a constant voltage and a high voltage for removing protrusions, which is higher than the constant voltage by a predetermined value, are applied between the electrodes of the radiation detector, and the voltage is periodically changed so as to include the instantaneous values. The currents of the electrodes corresponding to these voltage values are read periodically to measure the radiation dose and detect the abnormality of the radiation detector. Allows for discovery and removal of electrode products.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, the radiation detector 1 comprises a center electrode and a shell electrode. Of these, the shell electrode is grounded and the center electrode is connected to the variable voltage applying device 2. The variable voltage applying device 2 is a constant voltage that operates the radiation detector 1 and a voltage that periodically changes by including a high voltage for removing electrode products in an instantaneous value, that is, as shown in FIG. Generates a voltage with a constant voltage of 100 [V] superimposed on. Further, a current amplification device 3 that amplifies and outputs the current value of the voltage application path of the variable voltage application device 2 is provided, and the output current thereof is supplied to the current reading device 4.
The current reading device 4 obtains a synchronizing signal from the variable voltage applying device 2, samples a large number of current values corresponding to a plurality of voltages including a constant voltage and a high voltage, and outputs current value signals S ₁ , ..., S _n , respectively. Output. Then, the determination device 5 is adapted to measure the radiation dose and determine the detector abnormality based on the current value signals S ₁ , ..., S _n .

The operation of this embodiment configured as described above will be described below.

The voltage V applied to the electrodes of the radiation detector 1,
There is a relationship shown in FIG. 2 (a) between the current i flowing through this electrode. That is, when the gas pressure or the like in the electrode space is kept at a desired value, the current i rapidly increases when the voltage V is small, and then the voltage V is considerably wide, as shown by the solid line. The current i becomes constant over a period of time, and the current i increases again in the range where the voltage V is large. Constant voltage 10
0 [V] is defined in the middle part where the current becomes flat. Then, at the time of an abnormality such as a change in gas pressure between the electrodes, as indicated by "abnormality 1" and "abnormality 2" depending on the extent of the abnormality, the current i changes with respect to the change in voltage V
There is no flat part where is constant, and the entire curve has a rising characteristic.

As shown in FIG. 2B, the variable voltage applying device 2 generates a voltage in which a constant voltage of 100 [V] is superposed on an AC voltage and applies the voltage between the electrodes of the radiation detector 1. in this case,
As the amplitude of the AC voltage, a value that can remove the electrode-forming substance at the maximum voltage is selected. The current flowing through the electrodes by such a voltage is amplified by the current amplification device 3 and is read by the current reading device 4
Is taken into.

The current reading device 4 is a variable voltage applying device 2.
From, for example, receiving a synchronization pulse generated at each zero-cross point, 0 °, 45 °, 90 °, 135 °, 1
Current value S ₁ output from the current amplifier 3 at each sampling point of 80 °, 225 °, 270 °, 315 °, 360 °,
Reads _{S 2, S 3, S 2} , S 1, S 4, S 5, S 4, S 1, and outputs a current value signal periodically organize each the same voltage.

Therefore, as shown in FIG. 3, the determination device 5 measures the current change at a constant voltage of 100 [V], that is, the radiation dose, based on the data series of the current value S ₁ , while
_{S 2, S 3, S 4} , and determines an abnormality of the detector itself from the data sequence S _5.

In this case, from the characteristic curve in "normal" shown in FIG. 4, it is confirmed that the characteristic curve has changed as "abnormal 1" or "abnormal 2", and then the abnormality of the detector is detected. Make a decision.

Generally, the current value S _{1 is} changed by the change of gas pressure and the like.
, It is difficult to determine that the detector is abnormal because the change is small, but since the current values S ₂ and S ₃ change relatively greatly, it is possible to detect the detector abnormality early. it can.

On the other hand, the amplitude of the alternating current superimposed on the constant voltage of 100 [V] is selected so that the protrusions formed on the electrode surface can be removed, and the voltage corresponding to the current value S ₃ is applied between the electrodes. The protrusions are removed each time. This enables accurate measurement of radiation dose.

Thus, according to this embodiment, the abnormality of the detector can be detected before the measurement data is affected, and
Anomalies can be detected and electrode products can be removed without interrupting normal measurement.

Further, in the above embodiment, since the current value is periodically read at a large number of sampling points, the change in the capacity of the detector can be measured by measuring the rate of change of each current value, and the detector is damaged. There is also an effect that the etc. can be discovered early.

FIG. 5 is an explanatory view of another embodiment of the present invention, in which a constant voltage of 10 is applied as a voltage applied between the electrodes of the detector.
Using a rectangular wave superimposed on 0 [V], the current values S ₁ and S ₂ are set at a constant cycle determined to include the constant voltage and the maximum voltage.
Is read. This also allows the measurement of the radiation dose and the early detection of abnormalities and the removal of electrode products without interrupting this measurement.

[0022]

As is apparent from the above description, according to the present invention, it is possible to detect a detector abnormality at an early stage and remove an electrode product without interrupting the usual measurement of radiation dose.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a voltage and a current and a relationship between a voltage and a time, for explaining the operation of the embodiment of the present invention.

FIG. 3 is a diagram showing a change over time of a current reading value for explaining the operation of one embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between voltage and current to explain the operation of one embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between voltage and current and a relationship between voltage and time for explaining another embodiment of the present invention.

[Explanation of symbols]

 1 Radiation Detector 2 Variable Voltage Applying Device 3 Current Amplifying Device 4 Current Reading Device 5 Judging Device

Claims (1)

Claim: What is claimed is: 1. A radiation detector for radiating an electric field formed by applying a constant voltage between electrodes to detect a current flowing through the electrodes; Variable voltage applying device that applies a voltage that cyclically changes so as to include a high voltage that is higher by a certain value to each instantaneous value, and the electrodes that correspond to a plurality of voltage values including at least the constant voltage and the high voltage. And a current reading device for periodically reading the current, the radiation amount is measured from the read current value for the constant voltage, and the abnormality of the radiation detector is detected from the read current value for the voltage other than the constant voltage. Radiation measuring device characterized by.