JP4387994B2 - Criticality alarm device and test method thereof - Google Patents

Description

  The present invention relates to a criticality alarm device used for detecting a criticality accident in a facility for handling radioactive materials such as nuclear fuel and a test method thereof.

  In reprocessing plants, nuclear fuel waste processing plants, etc., criticality warning devices are installed to monitor the amount of radiation emitted from nuclear fuel collected in the facility and prevent nuclear fuel from reaching criticality. (Patent Document 1).

  As shown in FIG. 6, the conventional criticality alarm device generally includes a set of three radiation detectors 1a, 1b, 1c installed around the monitored device, and a set of two 2/3 logic circuits 2a, 2b, 2c, one alarm generation circuit 3, one set of warning light 4 and horn blower 5, and one test circuit 6 (Patent Document 2).

When the radiation levels detected by the radiation detectors 1a, 1b, and 1c exceed a certain amount, signals are output from the radiation detectors 1a, 1b, and 1c to the 2/3 logic circuits 2a, 2b, and 2c. The 2/3 logic circuits 2a, 2b, 2c are judged as critical events when a signal output from two or more of the three detectors 1a, 1b, 1c continues simultaneously for a certain period of time, and an alarm is generated. Output to circuit 3. In this case, the event of only one radiation detector is ignored. This is because the critical warning is an important warning that prompts the evacuation of related persons, and it is necessary to eliminate false alarms due to noise or the like as much as possible. For the same reason, the alarm generating circuit 3 determines that it is a critical event and operates the horn blower 5 and the warning lamp 4 when the signal output from two or more of the 2/3 logic circuits continues for a certain time at the same time. .
Japanese Patent No. 3046434 JP 2000-131488 A

  In the above-described conventional criticality alarm device, since the alarm generation circuit 3 is one, when the alarm output is temporarily interrupted at the time of the test for checking the soundness of the circuit, or the circuit is replaced due to a failure or the like. In this case, the output of the 2/3 logic circuit is directly connected to the warning light 4 or the like to cope with a human system.

When two alarm generation circuits 2 are used and redundancy is performed to automate the soundness test, it is not necessary to temporarily respond to the critical alarm in the human system, but there are the following problems.
That is, when the input signal line of the alarm generation circuit subject to the soundness test is cut off and a simulated signal is input, when the other alarm generation circuit is in a non-operating state such as a power failure, a criticality alarm is given during the test. Loss of function.

Also, if the input / output signal lines of the alarm generation circuit are shut off simultaneously during testing due to erroneous operation, the critical alarm function is lost during the test.
Furthermore, when checking the soundness of one alarm generation circuit, if the power supply of the other alarm generation circuit is normal but the function is abnormal, the critical alarm function is temporarily lost during the test.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a criticality alarm device that maintains a criticality alarm function even during a test of an alarm generation circuit, and a test method therefor.

  In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that a plurality of radiation detectors and a predetermined number of the plurality of radiation detectors connected to the plurality of radiation detectors generate detection signals. A plurality of logic circuits that sometimes output signals, and two alarm generation circuits that are connected to the plurality of logic circuits and that output a warning signal when a predetermined number of the plurality of logic circuits generate a signal And a test circuit for testing the alarm generation circuit, and when one alarm output is shut off at the time of soundness test or replacement of the alarm generation circuit, the other unit is in an inoperative state. And the alarm output is cut off only when the other unit is in an operating state.

  The invention according to claim 3 is a plurality of radiation detectors and a plurality of radiation detectors connected to the plurality of radiation detectors and outputting a signal when a predetermined number of the plurality of radiation detectors generate a detection signal. A logic circuit, an alarm generation circuit that outputs an alarm signal when a predetermined number of the plurality of logic circuits are connected to the plurality of logic circuits and generates a detection signal, and is connected in parallel to the alarm generation circuit In the critical alarm device test method comprising a backup circuit and a test circuit for testing the alarm generation circuit, the soundness of the operation of the backup circuit is confirmed, and then the alarm output of the alarm generation circuit is shut off. Thus, a soundness test of the alarm generation circuit is performed.

  According to the present invention, it is possible to provide a criticality alarm device in which the criticality alarm function is always maintained even during a test of an alarm generation circuit and a test method therefor.

Hereinafter, two embodiments of a criticality alarm device and a test method thereof according to the present invention will be described with reference to the drawings.
(First embodiment)
As shown in FIG. 1, the criticality alarm device of the present embodiment includes radiation detectors 1a, 1b, 1c, 2/3 logic circuits 2a, 2b, 2c, alarm generation circuits 3a, 3b, a test circuit 6, and an OR circuit. 7, a warning light 4 and a horn blower 5.

FIG. 2 shows configurations of the alarm generation circuits 3a and 3b and the test circuit 6.
Each of the alarm generation circuits 3a and 3b includes input unit AND circuits 21a and 21b, 2/3 criticality determination circuits 22a and 22b, output unit AND circuits 23a and 23b, NOT circuits 24a and 24b, and power supplies 25a and 25b. .

  The test circuit 6 includes a simulation signal generation circuit 35, a simulation signal generation circuit input changeover switch 31, a simulation signal generation circuit output changeover switch 32, an alarm generation circuit input / output cutoff signal changeover switch 33, an alarm generation circuit power supply monitor signal changeover switch 34, Timers 36 and 37, an alarm generation circuit selector switch 38, a 2/3 criticality judgment circuit test switch 39, and a test condition judgment AND circuit 40 are provided.

  In the configuration as described above, when checking the soundness of the alarm generation circuit 3a, the simulation signal from the test circuit 6 is input to the 2/3 criticality judgment circuit 22a to check whether or not the circuit operates normally. To do. In that case, it operates as follows.

That is, a signal is output from the test circuit 6 so that a critical alarm is not output by the simulated signal, and the signal is interrupted by the AND circuit 23a provided at the output of the alarm generation circuit 3a.
Further, the signal from the input side is blocked using the AND circuit 21a so that the test is not disturbed by the signal from the input side of the 2/3 criticality judgment circuit 22a of the alarm generation circuit 3a.

  When the soundness test of the alarm generation circuits 3a and 3b is performed, if the other alarm generation circuits 3a and 3b are inoperative such as a power failure, the signal of the alarm generation circuits 3a and 3b is temporarily cut off for the test. The critical alarm function is lost. Therefore, it is as follows.

That is, when the power supply of the other alarm generation circuit is cut off, the input / output units of the 2/3 criticality judgment circuits 22a and 22b cannot be cut off.
In addition, the alarm switch 3a, 3b can be tested only by one of the two switches by the changeover switch 31, and the input / output signals of the two systems are not interrupted at the same time. Will not be lost.

  The details of the operation will be described. First, in the test circuit 6, the switch 38 is used to select which test of the alarm generation circuits 3a and 3b is to be performed. By the switch selection, the test circuit 6 is connected to, for example, the alarm generation circuit 3a via the changeover switches 31, 32, 33, and 34. The changeover switch 34 connects the test circuit 6 to a signal line indicating the state of the power supply 25b of the alarm generation circuit 3b. After that, after the switching end time set by the timer 37, the 2/3 criticality judgment circuit test switch 39 is turned on, and the test condition judgment AND circuit 40 turns on the power supply 25b from the AND of the test start condition and the power supply 25b. The test can be started only in the case of. The ON signal is inverted by the NOT circuit 24a via the changeover switch 33, and is led to the input unit AND circuit 21a and the output unit AND circuit 23a of the alarm generation circuit 3a to cut off the signal line.

  Next, after the delay time set by the timer 36, the simulation signal generation circuit 35 inputs the signal to the 2/3 criticality determination circuit 22a of the alarm generation circuit 3a through the changeover switch 32 for switching the test signal. Then, the output of the 2/3 criticality determination circuit 22a is input to the simulation signal generation circuit 35 via the changeover switch 31, and the soundness is determined as shown in FIG. FIG. 3A shows that an output signal (broken line) is not output from the 2/3 criticality judgment circuit 22a within a predetermined time (ΔT) with a signal of only one line out of the three lines. ) Is output from the 2/3 criticality judgment circuit 22a (dashed line) within a predetermined time (ΔT) when a signal output of any 2 lines or more (a.b line in the figure) in 3 lines is output. It is determined that the alarm generation circuit 3a is normal.

In this way, the ON / OFF state of the power supply 25b of the other critical alarm generation circuit 3b is confirmed, and the soundness test of the alarm generation circuit 3a is performed.
As for the soundness of the alarm generation circuit 3b, the soundness test is performed in the same manner as the alarm generation circuit 3a by selecting b with the changeover switch 38.

  In the criticality alarm device of the present embodiment, during the soundness test of the alarm generation circuits 3a and 3b, when the power supply of other alarm generation circuits is down, the alarm generation circuit is not tested. The signals at the input / output portions of the 2/3 criticality judgment circuits 22a and 22b can be maintained to prevent temporary loss of criticality alarm functions during testing.

  In addition, the switches 31, 32, 33 and 34 cannot test the two alarm generation circuits 3a and 3b at the same time, and the two input / output signals are cut off at the same time due to an erroneous operation or the like. It is possible to prevent the alarm function from being lost.

(Second Embodiment)
Next, a second embodiment of the criticality alarm device and the test method thereof according to the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

As shown in FIG. 4, in the critical alarm device of the second embodiment, the alarm generation circuit 3a further includes a timer 27 as compared with the critical alarm device of the first embodiment, and includes a backup circuit 26 and an output unit OR. A circuit 28 is connected.
The test circuit 6 further includes a backup circuit test switch 41 and a backup circuit test AND circuit 42, as compared with the criticality alarm device of the first embodiment.

  When performing the soundness test of the alarm generation circuit 3a, the criticality alarm device of the second embodiment performs a series of soundness tests as in the first embodiment after the backup circuit 26 is connected in parallel. . The output of the backup circuit 26 is ORed with the signal from the alarm generation circuit 3a by the output unit OR circuit 28 and output. The backup circuit 26 is installed only in the alarm generation circuit 3a. This is because, when the soundness of the alarm generation circuit 3a is confirmed, the soundness test of the alarm generation circuit 3b can be performed using the alarm generation circuit 3a whose soundness has been confirmed.

  The criticality alarm function is ensured by confirming the soundness of the backup circuit 26 before the test, and the test can be performed regardless of the soundness of the other alarm generation circuits 3b of the two units.

The operation of each circuit will be described below.
The changeover switch 38 of the test circuit 6 selects which of the alarm generation circuits 3a and 3b is to be tested. By this switch selection, the test circuit 6 is connected to, for example, the alarm generation circuit 3a by the changeover switches 31, 32, 33, and 34. Thereafter, after the switching end time set in the timer 37, the 2/3 criticality judgment circuit test switch 39 is turned on, and the backup circuit 26 enters the operating state via the changeover switch 33. That is, in the backup circuit 26 shown in FIG. 5A, the input unit AND circuit 50 and the output unit AND circuit 52 are turned on and are in an operating state. Even in the circuit configuration of FIG.

  Next, after a time set by the timer 27, a signal is sent to the input unit AND circuit 21a and the output unit AND circuit 23a of the alarm generation circuit 3a via the NOT circuit 24a to cut off the signal line. Further, after the time set by the timer 36, the signal from the simulation signal generation circuit 35 of the test circuit 6 is input to the 2/3 criticality determination circuit 22a of the alarm generation circuit 3a. Then, the output of the 2/3 criticality determination circuit 22a is input to the simulation signal generation circuit 35 via the changeover switch 31, and the soundness is determined as shown in FIG.

  The soundness test of the backup circuit 26 is performed in advance, and the backup circuit test switch 41 is turned ON and only when the signal line of the backup circuit 26 is in the cut-off state (this operation is performed by the AND circuit 42). The test is performed with the generation circuit 35 turned ON.

  In the test method for the criticality alarm device of the present embodiment, since the backup circuit 26 that has been confirmed in advance is connected in parallel, when the soundness of the alarm generation circuits 3a and 3b is inspected, Even if the function is abnormal, the critical alarm function is not lost even during the test, and the reliability is improved.

The figure which shows the structure of the criticality alarm apparatus of the 1st Embodiment of this invention. The figure which shows the structure of the alarm generation circuit and test circuit in the criticality alarm apparatus of the 1st Embodiment of this invention. The figure explaining operation | movement of the criticality alarm apparatus of the 1st Embodiment of this invention. The figure which shows the circuit structure of the test method of the criticality alarm apparatus of the 2nd Embodiment of this invention. The figure which shows the structure of the backup circuit in the test method of the criticality alarm apparatus of the 2nd Embodiment of this invention. The figure which shows the structure of the conventional criticality alarm apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1a, 1b, 1c ... Radiation detector, 2a, 2b, 2c ... 2/3 logic circuit, 3, 3a, 3b ... Alarm generating circuit, 4 ... Warning light, 5 ... Horn blower, 6 ... Test circuit, 7 ... OR circuit , 21a, 21b ... input unit AND circuit, 22a, 22b ... 2/3 criticality judgment circuit, 23a, 23b ... output unit AND circuit, 24a, 24b ... NOT circuit, 25a, 25b ... power supply, 26 ... backup circuit, 27 ... Timer ... 28 ... Output unit OR circuit, 31 ... Simulated signal generating circuit input selector switch, 32 ... Simulated signal generating circuit output selector switch, 33 ... Alarm generating circuit I / O cutoff signal selector switch, 34 ... Alarm generating circuit power monitor signal selector Switch 35 ... Simulated signal generating circuit 36 ... Timer 37 ... Timer 38 ... Alarm generating circuit selector switch 39 ... 2/3 criticality judgment circuit test switch 40 ... Test condition judgment Constant AND circuit, 41 ... Backup circuit test switch, 42 ... Backup circuit test AND circuit, 50 ... Input part AND circuit, 51 ... 2/3 criticality judgment circuit, 52 ... Output part AND circuit, 53 ... Display LED, 54 ... Output unit OR circuit.

Claims (4)

  A plurality of radiation detectors, a plurality of logic circuits connected to the plurality of radiation detectors and outputting a signal when a predetermined number of the plurality of radiation detectors generate a detection signal, and the plurality of logics A plurality of alarm generating circuits that output an alarm signal when a predetermined number of the plurality of logic circuits connected to the circuit generates a signal, and a test circuit that tests the alarm generating circuit, When the predetermined alarm output of the alarm generation circuit is cut off, it is detected whether the other alarm generation circuit is in an inoperative state, and the alarm output is cut off only when at least one of the alarm generation circuits is in an operating state. A criticality alarm device.   2. The critical alarm device according to claim 1, wherein the alarm output is blocked by a changeover switch so that the outputs of a plurality of alarm generation circuits cannot be blocked simultaneously.   A plurality of radiation detectors, a plurality of logic circuits connected to the plurality of radiation detectors and outputting a signal when a predetermined number of the plurality of radiation detectors generate a detection signal, and the plurality of logics An alarm generation circuit for outputting an alarm signal when a predetermined number of the logic circuits connected to the circuit generates a detection signal, a backup circuit connected in parallel to the alarm generation circuit, and the alarm generation In a test method for a criticality alarm device comprising a test circuit for testing a circuit, the soundness of the alarm generation circuit is confirmed by checking the soundness of the operation of the backup circuit and then shutting off the alarm output of the alarm generation circuit A test method for a criticality alarm device, characterized by performing a test.   4. The test method for a criticality alarm device according to claim 3, wherein the backup circuit includes a 2/3 logic circuit or an OR circuit.

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