JPH04279891A - Criticality alarm device - Google Patents

Abstract

PURPOSE:To obtain a criticality alarm device, which drastically facilitates the determination of the cause of a generated criticality alarm. CONSTITUTION:A radiation detection signal output from a radiation detector 2 installed on a site where a nuclear material is handled, is input into a level judging part provided on the site side by a criticality alarm device, and when the signal level of the input radiation detection signal exceeds a predetermined reference, a criticality detection signal is output to a center surveyllance room through transmission route. A involatile memory 12 for storing the criticality detection signal output from the level judging part is provided on the site side.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a criticality warning system for detecting criticality accidents in nuclear fuel handling facilities.

0002

[Prior Art] In reprocessing plants, nuclear fuel waste processing plants, etc., a criticality alarm system configured as shown in Figure 3 is installed to monitor the amount of radiation emitted from the nuclear fuel collected within the facility. A criticality warning was output when there was a risk that the nuclear fuel would become critical.

In this criticality warning system, a criticality detection section 1 is installed at a facility (site) where nuclear fuel and the like are collected. This critical detection unit 1 detects gamma rays emitted from a detection target using a radiation detector 2 such as a scintillation detector, and sends this radiation detection signal to one input terminal of a comparator 3 attached to the radiation detector 2. input. A reference potential is set to the other input terminal of the comparator 3, and this reference value is compared with the input potential from the radiation detector 2. If the input potential is equal to or higher than the reference value, a trip signal is output. Ru. This trip signal is transmitted from a cable driver 4 provided in the criticality detection section 1 via a signal cable L to a criticality determination circuit 5 installed in the central monitoring room.

[0004] In the criticality warning device configured in this manner, three criticality detection sections are provided for one detection target, and each criticality detection section outputs a trip independently. Since criticality alarm devices are required to have extremely high reliability, reliability measures such as 2/3 logic are taken when determining the output of criticality alarms.

On the other hand, there is a very high possibility that various noises will be superimposed on the signal being transmitted through the signal cable L that connects the criticality detection unit 1 installed on the field side and the central monitoring room side.
The criticality determination circuit 5 may erroneously determine this noise as a trip signal.

If the criticality determination circuit 5 erroneously determines that noise superimposed on the signal cable L is a trip signal, a criticality alarm is output. In most cases, criticality alarms are caused by noise, but if the detection target has actually reached a critical state, then the cause must be removed; It is extremely important to investigate the cause of the alarm, such as whether the alarm was output because a condition has been reached or whether it is a false alarm due to noise.

[0007] However, in the criticality warning device, a trip is detected momentarily, and it is not possible to determine whether the outputted criticality warning is due to a true trip or external noise.

[0008]

[Problems to be Solved by the Invention] Therefore, in the conventional criticality alarm device, it is not possible to tell whether the criticality alarm is output because a critical state has actually been reached or whether it is a false alarm due to noise, and the criticality alarm output is It was extremely difficult to investigate the cause.

The present invention has been made in view of the above-mentioned circumstances, and it is difficult to determine whether the generated criticality alarm is output because the criticality state has actually been reached or whether it is caused by other factors such as noise. It is an object of the present invention to provide a criticality alarm device that allows it to be extremely easily confirmed whether the alarm has been output.

0010

[Means for Solving the Problems] In order to achieve the above object, a first invention provides a radiation detection signal outputted from a radiation detector installed at a site where nuclear fuel materials are handled. In a criticality alarm device that is input to a level determination section and outputs a criticality detection signal to a central monitoring room via a transmission line when the signal level of this input radiation detection signal exceeds a preset reference value, A non-volatile memory in which the criticality detection signal output from the level determination unit is stored is provided on the site side,

[0011]
In order to achieve the above object, the second invention divides the high voltage generated by a high voltage power supply into a plurality of voltage values using a voltage dividing resistor, and installs these plural voltage values at a site where nuclear fuel materials are handled. A radiation detection signal outputted from the radiation detector is inputted to a level determination section provided on the site side, and the signal level of this input radiation detection signal is applied to a preset standard. In a criticality alarm device that outputs a criticality detection signal to a central monitoring room via a transmission line when the value exceeds a value, the voltage appearing at the output terminal of the voltage dividing resistor provided on the site side is inputted, a comparison circuit that detects an abnormality in the high voltage power supply and the voltage dividing resistor and outputs an abnormality detection signal based on a comparison result between the input voltage and a preset reference value; The configuration includes a nonvolatile memory that stores an abnormality detection signal output from the comparison circuit, and a transmission means that sends the abnormality detection signal output from the comparison circuit onto the transmission path.

0012

According to the first invention, when a critical state is detected by the radiation detector, a criticality detection signal is output from the level determining section. This criticality detection signal is transmitted to the central monitoring room side via a transmission path, and is also stored in a nonvolatile memory installed at the site. Therefore, when a criticality alarm is output due to an actual criticality state, this fact is also stored in the nonvolatile memory, and the cause can be investigated extremely easily by checking the stored contents of the nonvolatile memory.

According to the second invention, when the resistance wire of the voltage dividing resistor that supplies the operating voltage of the radiation detector is disconnected or the voltage value of the high voltage power supply decreases, the abnormality detection signal is generated. The abnormality detection signal is sent to the criticality determination circuit so that abnormalities in on-site peripheral equipment can be detected extremely quickly, and the abnormality detection signal is stored in a nonvolatile memory.

[0014]

[Examples] Examples of the present invention will be described below. FIG. 1 shows the configuration of a criticality warning device according to a first embodiment of the present invention. Note that parts having the same functions as those of the device shown in FIG. 3 are given the same reference numerals.

[0015] In this criticality alarm device, a criticality detection unit 10 installed on the field side includes a radiation detector 2, a comparator 3,
In addition to the cable driver 4, there is also a latch circuit 11 consisting of a bistable multivibrator etc. that latches the trip output of the comparator 3, and a non-volatile memory consisting of an E2 PROM etc. which is connected to the output terminal of this latch circuit 11 and stores the latch output. It consists of 12. Note that for one detection target, three criticality detection sections configured as described above are installed, and each of them independently outputs a trip signal to the criticality determination circuit.

The criticality determination circuit 5 performs criticality determination based on 2/3 logic when there is a trip output to be detected, and outputs a criticality alarm when there are two or more trip outputs. In other words, even if a failure occurs in the processing path of one of the criticality detection units in a set of three, two detection units will operate normally and output a trip output, so criticality can be reliably detected. Even if the detector S erroneously outputs a trip, only one trip output is output, so the criticality determination circuit 5 does not output a criticality alarm based on that trip output. Therefore, false alarms are prevented.

In this embodiment configured in this manner, when the detection target reaches a critical state, the radiation detection signal output from the radiation detector 2 exceeds the reference potential set in the comparator 3, and the radiation detection signal is output from the comparator 3. A trip signal is output. This trip signal is transmitted via the cable driver 4 and signal cable L to the criticality determination circuit 5 in the central monitoring room.
and is latched by the latch circuit 11. As a result, the trip signal is stored in the nonvolatile memory 12. The criticality determination circuit 5 receives the trip signal from the criticality detection section 10 and outputs a criticality alarm based on 2/3 logic.

On the other hand, if the criticality determination circuit 5 erroneously determines a signal due to noise to be a trip signal and outputs a criticality alarm, the comparator 3 does not output a trip signal, so the nonvolatile memory 12 stores Nothing is remembered.

Therefore, according to this embodiment, the comparator 3
Since the output of is stored in the nonvolatile memory 12 also provided on the site side via the latch circuit 11 provided on the site side, when a critical state is actually detected, a true trip signal is output from the comparator 3. When the trip signal is output, the trip signal is stored in the non-volatile memory 12, and when the criticality judgment circuit 5 detects a trip signal due to noise etc., there is no change in the stored contents of the non-volatile memory 12, so the criticality alarm is issued. By checking the stored contents of the non-volatile memory 12 after the occurrence of the alarm, it is possible to determine whether the alarm is caused by a true trip signal or noise, making it extremely easy to investigate the cause of the occurrence of the critical alarm. . next,
A second embodiment of the present invention will be described.

FIG. 2 is a diagram showing a criticality warning device according to a second embodiment. Note that parts having the same functions as those of the first embodiment described above are given the same reference numerals, and different parts will be described in detail.

[0021] This criticality warning device is configured to store the occurrence of a failure in a peripheral device installed at the site in a non-volatile memory 13 installed at the site. For this purpose, the nonvolatile memory 13 stores the trip signal output from the comparator 3 that monitors the output of the radiation detector 2, the voltage drop of the high voltage power supply 21, and the bleeder resistor 2.
2 is configured to store a detection signal that detects the disconnection of the wire.

Generally, the radiation detector 2 operates by applying voltages obtained by dividing a high voltage generated by a high-voltage power supply 21 into a plurality of voltage values using a bleeder resistor 22 made up of a plurality of resistors. In this embodiment, the terminal output terminal of the bleeder resistor 22 is connected to one input terminal of the comparator 23, and this input voltage is compared with a reference potential set at the other input terminal. The output terminal of this comparator 23 is connected to the cable driver 4 and the latch circuit 24
It is connected to the. The latch circuit 24 is a comparator 2
3 is latched, and this latched trip signal is stored in the nonvolatile memory 13.

In this embodiment configured as described above, the trip output output from the comparator 3 due to radiation in the radiation detector 2 is stored in the nonvolatile memory 13, as in the first embodiment.

Further, when a drop in the high voltage power supply or a break in the bleeder resistor is detected by the comparator 23, the trip output resulting from this detection is transmitted to the criticality determination circuit 5 via the cable driver 4, and is held by the latch circuit 24. It is stored in the nonvolatile memory 13.

Since the criticality determination circuit 5 performs criticality determination using 2/3 logic, unless the peripheral devices of the three criticality detection units for the same detection target fail at the same time, the comparator monitoring the peripheral devices A criticality alarm is not output depending on the trip signal from 23, and it can be recognized that a failure has occurred in the peripheral equipment.

As described above, according to this embodiment, it is possible to check the stored contents of the non-volatile memory 13 to determine whether the generated criticality alarm is due to radiation detection or noise detection. This makes it extremely easy to investigate the cause of criticality alarm occurrence. Furthermore, detection signals that detect failures of the high-voltage power supply 21 and bleeder resistor 22 installed at the site are also stored in the non-volatile memory 13.
Since the information is stored in the memory and transmitted to the criticality determination circuit 5, failures in the high-voltage power supply 21 and the bleeder resistor 22 can be immediately detected and prompt action can be taken.

[0027]

[Effects of the Invention] As detailed above, according to the present invention, it is possible to determine whether a criticality alarm that is generated is output due to actually reaching a critical state or due to other factors such as noise. It is very easy to check whether
Furthermore, it is possible to provide a criticality warning device that can improve the reliability of the device.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a criticality warning device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a criticality warning device according to a second embodiment.

FIG. 3 is a configuration diagram of a conventional criticality warning device.

[Explanation of symbols]

2... Radiation detector, 3... Comparator, 4... Cable driver, 5... Criticality determination circuit, 10... Criticality detection unit, 11...
Latch circuit, 12... nonvolatile memory.

Claims (2)

[Claims] Claim 1: A radiation detection signal output from a radiation detector installed at a site where nuclear fuel materials are handled is inputted to a level determination section provided at the site, and the signal level of the input radiation detection signal is determined in advance. In a criticality alarm device that outputs a criticality detection signal to a central monitoring room via a transmission line when a set reference value is exceeded, a non-volatile device stores the criticality detection signal output from the level determination section. A criticality alarm device characterized in that a memory is provided on the site side. Claim 2: Divide the high voltage generated by a high-voltage power supply into multiple voltage values using a voltage dividing resistor, and apply these multiple voltage values to a radiation detector installed at a site where nuclear fuel materials are handled; The radiation detection signal output from this radiation detector is input to the level determination section provided on the site side, and when the signal level of this input radiation detection signal exceeds a preset reference value, the central monitoring room In a criticality alarm device that outputs a criticality detection signal via a transmission line to a device, a voltage provided at the site side and appearing at an output terminal of the voltage dividing resistor is input, and is preset with this input voltage. a comparison circuit that detects an abnormality in the high voltage power supply and the voltage dividing resistor based on a comparison result with a reference value and outputs an abnormality detection signal;
A nonvolatile memory provided on the field side and storing an abnormality detection signal output from the comparison circuit, and a transmission means for transmitting the abnormality detection signal output from the comparison circuit onto the transmission path. A criticality warning device characterized by: