JPH05264737A - Criticality alarm apparatus - Google Patents

Abstract

PURPOSE:To provide a criticality alarm apparatus which can remove external noise and further can inform that the external noise has mixed. CONSTITUTION:A criticality alarm apparatus comprises at least three radiation detectors 11 to 13 which output logic signals when a radiation level exceeds a predetermined value, a 2/3 logic circuit 2 to which majority of the logic signals 11 to 13 are input for outputting a logic output signal when input retention time of the logic signals is within a first predetermined value, and an OR circuit 4 for outputting a signal when at least one of the logic signals from the respective radiation detectors 11 to 13 is input. It further comprises a timer 5 for determining if time since the output of 4 is caused until the output disappears is a second predetermined time or more and outputting a logic signal when it is the second predetermined value or more and an AND circuit 6 which admits the logic signal from the timer 5 and the logic signal from the 2/3 logic circuit 2 and outputs a critical signal when both exist simultaneously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a criticality warning device installed at a place where nuclear fuel material is handled and used for detecting a criticality accident.

[0002]

2. Description of the Related Art Conventionally, as an example of a criticality warning device, FIG.
As shown in, the radiation detectors 11, 12, and 13 arranged at the place where the radiation dose should be measured, and the radiation detectors are installed on the center side,
It is composed of a 2/3 logic module having a 2/3 logic circuit 2 and an electronic timer 3. Radiation detectors 11-1
3 detects the radiation level and inputs a logic signal generated when this level exceeds a predetermined value to the 2/3 logic circuit 2. Then, in the 2/3 logic circuit 2, when the logic signals from at least two of the radiation detectors 11 to 13 are input together within the time set by the electronic timer 3, for example, 500 ms, a critical signal is output. It has become so.

[0003]

In the example of FIG. 3, the external noise to the detection signals of the radiation detectors 11 to 13 is reduced to 2 /.
In the 3 logic circuit 2, no measure is taken to remove it logically, so that the original function is exhibited when no external noise occurs.

In reality, however, the generation of external noise cannot be avoided, and it is impossible to determine whether the output of the 2/3 logic circuit 2 is due to a true radiation signal or external noise. Therefore, there is a demand for the development of a critical warning device that can remove external noise and can notify that external noise is mixed.

The present invention has been made to meet such a demand, and an object of the present invention is to provide a critical alarm device capable of removing external noise and notifying that external noise is mixed. It is in.

[0006]

In order to achieve the above object, the present invention is configured as follows. That is, the invention according to claim 1 is provided with at least three radiation detectors which are arranged at a place where a radiation dose is to be measured, and which output a logical signal when the radiation level exceeds a predetermined value, and each radiation detection device. Majority logic circuit for inputting a logic signal of a logic device and a majority of the logic signals is input and the input duration of the logic signal is within a first predetermined value, and a majority logic circuit for outputting a logic output signal, and each of the radiations. A logical sum circuit for inputting a logical signal of the detector and outputting a signal when at least one logical signal is input, and a time from the output of the logical sum circuit until the output disappears 2 is a predetermined time or more, and if it is longer than a second predetermined time, a timer that outputs a logic signal, a logic signal from this timer and a logic signal from the majority logic circuit are input, and both are input. And a logical product circuit for outputting a critical signal when present in. Further, the invention according to claim 2 is provided with at least three radiation detectors which are arranged at a place where the radiation dose is to be measured, and which output a logical signal when the radiation level exceeds a predetermined value, and each radiation detection device. Input the logic signal of the instrument, and when more than half of the logic signal is input and the input duration of the logic signal is within the first predetermined value,
A majority logic circuit that outputs a logic output signal, a logic sum circuit that inputs the logic signal of each radiation detector, and outputs a signal when at least one logic signal is input, and an output of this logic sum circuit Is generated and the time until the output disappears is determined whether it is a second predetermined time or longer, and when it is longer than the second predetermined time, a timer that outputs a logic signal and an output from the logical sum circuit are output. And a notification device for outputting a signal for notifying that external noise is mixed in when the logic signal is generated from the timer.

[0007]

According to the invention according to claim 1, the logic signal detected by the radiation detector has a second predetermined time, for example, 1 ms.
Since the critical signal is output only when the time is larger than the first predetermined time, for example, 500 ms or less, external noise can be removed.

According to the second aspect of the invention, when the radiation detector outputs the logic signal and the timer does not output the logic signal, the alarm informs that the external noise is mixed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of the present invention, and FIG. 3 is different from the conventional example of FIG. 3 in that an OR circuit 4, an electronic timer 5, AND circuits 6, 7 and an indicator lamp 8 are added. Is a different point.

The OR circuit 4 includes radiation detectors 11-13.
Of the logic signals, and outputs a signal when at least one of the logic signals is input. The electronic timer 5
It is determined whether the time from the output of the OR circuit 4 until the output disappears is the second predetermined time, for example, 1 ms or more, and if it is 1 ms or more, the logic signal is output.
The AND circuit 6 inputs the logic signal from the timer 5 and the logic signal from the majority logic circuit, for example, the 2/3 logic circuit 2, and outputs a critical signal when both are present. When the output from the logical sum circuit 4 is generated and the logical signal is not output from the timer 5, the logical product circuit 7 outputs a signal notifying that external noise is mixed. The indicator lamp 8 is an example of an annunciator and is turned on when a logical signal is generated from the logical product circuit 7.

The operation of the criticality warning device of this embodiment thus constructed will be described below with reference to FIG.
Now, when the radiation is detected by the radiation detectors 11 and 12, and the signal shown in FIG. 2A, that is, the logic signal of 1 ms or more is input to the logical sum circuit 4, the logic signal is output from the timer 5. Is output. On the other hand, the radiation detectors 11 and 1
The logic signal from 2 is input to the 2/3 logic circuit 2, and 2
A logic signal is generated from the / 3 logic circuit 2, and this and the logic signal from the timer 5 are both input to the AND circuit 6, so that the AND circuit 6 outputs a critical signal.

As described above, in the timer 5, 1 ms
The reason for setting is as follows. Generally, the signal due to the mixing of external noise is short in a pulse shape and is 1 ms.
This is because, since there are many cases below, external noise can be removed by setting the timer 5 to 1 ms. As described above, in the present embodiment, the output of the logical product circuit 6, that is, the critical signal is a signal of 1 ms or more and 2/500 ms or less.
3 Only obtained when the logic circuit 2 is satisfied.

In the embodiment described above, the radiation detector 11,
The logic signal detected by 12 is 1 ms or more, but when the logic signal detected by the radiation detectors 11 and 12 is less than 1 ms as shown in FIG. Since the signal is output from 7, the indicator lamp 8 is turned on. Since the indicator lamp 8 is turned on, it is possible to determine that external noise is mixed in the radiation detectors 11 and 12. In this case, since the logic signal is not output from the timer 5, the critical signal from the AND circuit 6 does not occur.

In the embodiment described above, the electronic timer 3,
The setting times of 5 are 500 ms and 1 ms, respectively,
It goes without saying that the value is not limited to this, and other values may be used.

[0015]

As described above, according to the present invention, it is possible to provide a critical alarm device capable of removing external noise and further notifying that external noise is mixed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a criticality warning device according to the present invention.

FIG. 2 is a time chart for explaining the operation of FIG.

FIG. 3 is a block diagram showing a schematic configuration of an example of a conventional criticality warning device.

[Explanation of symbols]

11, 12, 13, ... Radiation detector, 2 ... 2/3 logic circuit, 3 ... Electronic timer, 4 ... Logical sum circuit, 5 ... Electronic timer, 6, 7 ... AND circuit, 8 ... Indicator light.

Claims (2)

[Claims] 1. Arranged at a place where a radiation dose is to be measured,
At least three radiation detectors that output a logic signal when the radiation level exceeds a predetermined value, and the logic signals of these radiation detectors are input, and a majority of the logic signals are input, and A majority logic circuit that outputs a logic output signal when the input duration is within a first predetermined value, and a logic signal of each of the radiation detectors is input, and a signal is output when at least one of the logic signals is input. A logical sum circuit for outputting, and it is determined whether the time from the generation of the output of the logical sum circuit to the disappearance of the output is a second predetermined time or more, and if the second predetermined time or more, a logical signal A criticality warning device comprising: a timer that outputs a logic signal; and a logical product circuit that inputs a logic signal from the timer and a logic signal from the majority logic circuit and outputs a critical signal when both are present. 2. Arranged at the place where the radiation dose should be measured,
At least three radiation detectors that output a logic signal when the radiation level exceeds a predetermined value, and the logic signals of these radiation detectors are input, and a majority of the logic signals are input, and A majority logic circuit that outputs a logic output signal when the input duration is within a first predetermined value, and a logic signal of each of the radiation detectors is input, and a signal is output when at least one of the logic signals is input. A logical sum circuit for outputting, and it is determined whether the time from the generation of the output of the logical sum circuit to the disappearance of the output is a second predetermined time or more, and if the second predetermined time or more, a logical signal And a notification device that outputs a signal for notifying that external noise is mixed when an output is generated from the OR circuit and a logic signal is not output from the timer. Field warning device.