JP3103185B2 - Criticality warning device - Google Patents

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 FIG.
As shown in the figure, the radiation detectors 11, 12, and 13 are arranged at the place where the radiation dose is to be measured,
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
Numeral 3 detects a radiation level, and inputs a logic signal generated when this level exceeds a predetermined value to the 2/3 logic circuit 2. In the 2/3 logic circuit 2, when a logic signal from at least two of the radiation detectors 11 to 13 is input together within a time set by the electronic timer 3, for example, within 500 ms, a critical signal is output. It has become so.

[0003]

FIG. 3 shows an example in which the external noise corresponding to the detection signals of the radiation detectors 11 to 13 is represented by 2 /
Since no countermeasures are taken in the three logic circuits 2 for logical removal, the original function is exhibited when no external noise occurs.

However, in reality, generation of external noise is inevitable, and it is impossible to determine whether the output of the 2/3 logic circuit 2 is a true radiation signal or external noise. For this reason, there is a demand for the development of a criticality alarm device capable of removing external noise and notifying that external noise has been mixed.

SUMMARY OF THE INVENTION The present invention has been made to satisfy such a demand. It is an object of the present invention to provide a criticality alarm device capable of removing extraneous noise and notifying that extraneous noise has been mixed. It is in.

[0006]

Means for Solving the Problems The present invention has the following configuration to achieve the above object. That is, the invention according to claim 1 is provided at least three radiation detectors which are arranged at a place where a radiation dose is to be measured and output a logic signal when the radiation level exceeds a predetermined value, and each of the radiation detectors A majority logic circuit for inputting a logic signal of a detector, and when a majority of the logic signal is input and the input duration time of the logic signal is within a first predetermined value, a majority logic circuit for outputting a logic output signal; A logical sum circuit that inputs a logical signal of the detector and outputs a signal when at least one of the logical signals is input, and a time from when the output of the logical sum circuit occurs until the output disappears, And a timer for outputting a logic signal if the second predetermined time or more, and a logic signal from the timer and a logic signal from the majority logic circuit are input. And a logical product circuit for outputting a critical signal when present in. According to a second aspect of the present invention, there is provided at least three radiation detectors disposed at a place where a radiation dose is to be measured and outputting a logical signal when the radiation level exceeds a predetermined value, and each of the radiation detectors. When a logic signal of the device is inputted, and more than half of the logic signal is inputted, and the input duration of the logic signal is within a first predetermined value,
A majority logic circuit that outputs a logic output signal; a logic circuit that receives a logic signal of each of the radiation detectors and outputs a signal when at least one of the logic signals is input; and an output of the logic circuit. It is determined whether or not the time from when the output disappears until the output disappears is equal to or longer than a second predetermined time. If the time is equal to or longer than the second predetermined time, a timer that outputs a logic signal and an output from the OR circuit are output. And a notifier for outputting a signal notifying that external noise has been mixed in when the logic signal is generated and the logic signal is not output from the timer.

[0007]

According to the invention corresponding to the first aspect, 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 it is longer than the first predetermined time, for example, 500 ms or less, external noise can be removed.

According to the second aspect of the present invention, when the logic signal is output from the radiation detector and the logic signal is not output from the timer, the notification that the external noise has entered is provided by the notification device.

[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. The point that an OR circuit 4, an electronic timer 5, AND circuits 6, 7 and an indicator lamp 8 are added to the conventional example of FIG. Is a different point.

The OR circuit 4 includes radiation detectors 11 to 13
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 when the output of the OR circuit 4 occurs until the output disappears is a second predetermined time, for example, 1 ms or more. If it is 1 ms or more, a logic signal is output.
The AND circuit 6 receives 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 an output is generated from the OR circuit 4 and a logical signal is not output from the timer 5, the AND circuit 7 outputs a signal notifying that external noise is mixed. The indicator lamp 8 is turned on when a logical signal is generated from the AND circuit 7 as an example of an alarm.

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

As described above, in the timer 5, 1 ms
Is set for the following reasons. In general, the signal due to external noise is short, pulse-like, 1 ms
This is because external noise can be removed by setting the timer 5 to 1 ms because there are many cases as follows. As described above, in the present embodiment, the output of the AND circuit 6, that is, the critical signal is a signal of 1 ms or more and 2/500 or less within 500 ms.
It is obtained only when three logic circuits 2 are satisfied.

The above-described embodiment is directed to the radiation detector 11,
In the case where the logical signal detected by the radiation detector 12 is 1 ms or more, when the logical 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 extraneous noise has entered the radiation detectors 11 and 12. In this case, since a logic signal is not output from the timer 5, a critical signal from the AND circuit 6 does not occur.

In the embodiment described above, the electronic timer 3,
The set times of 5 were 500 ms and 1 ms, respectively.
Needless to say, the value is not limited to this and may be another value.

[0015]

According to the present invention, it is possible to provide a criticality alarm device capable of removing extraneous noise and notifying that extraneous noise has been mixed.

[Brief description of the 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. 1;

FIG. 3 is a block diagram showing a schematic configuration of an example of a conventional criticality alarm 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 ... logical product circuit, 8 ... indicator lamp.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01T 1/17 G01T 3/00 G21C 17/06

Claims (2)

(57) [Claims] Claims: 1. A method according to claim 1, wherein the radiation dose is to be measured.
At least three radiation detectors that output a logical signal when the radiation level exceeds a predetermined value; a logical signal of each of the radiation detectors is input; more than a majority of the logical signals are input; 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, and a signal when at least one of the logic signals is input. An OR circuit for outputting, and determining whether or not the time from when the output of the OR circuit is generated until the output disappears is equal to or longer than a second predetermined time. And a logical product circuit that receives the logic signal from the timer and the logic signal from the majority logic circuit and outputs a critical signal when both are present. 2. A device for measuring a radiation dose, wherein the radiation dose is to be measured,
At least three radiation detectors that output a logical signal when the radiation level exceeds a predetermined value; a logical signal of each of the radiation detectors is input; more than a majority of the logical signals are input; 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, and a signal when at least one of the logic signals is input. An OR circuit for outputting, and determining whether or not the time from when the output of the OR circuit is generated until the output disappears is equal to or longer than a second predetermined time. And a notifier that outputs a signal notifying that external noise has been mixed when an output is generated from the OR circuit and a logical signal is not output from the timer. Field warning device.