JP3251730B2 - Control rod position detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control rod position detecting device for a control rod driving device of a nuclear power plant, which has a drift diagnosis circuit for detecting unnecessary operation of the control rod.

[0002]

2. Description of the Related Art A position detector of a control rod driving device of a nuclear power plant has a double structure in order to improve reliability and operation rate. The control device switches the output signal of the duplicated position detector and uses it as a representative signal.
By using this representative signal, control rod position control,
And an abnormality detection for diagnosing the normality of the position control. In position control, the position changes when it is not in a state to be driven. In other words, a change in the position signal is abnormal because the control rod is moving without permission. Hereinafter, this state is called drift. When drift is detected, the controller issues an alarm and notifies the operator.

FIG. 4 shows a configuration diagram of a conventional control rod position detecting circuit for detecting drift of a control rod position signal. A system,
For the position signals S1 and S3 duplicated with the B system, the position signal switching circuit 1 selects either the A system or the B system position signal as the representative position signal S3. Representative position signal S3
Are used for the position control function, which is the original purpose of the control rod drive, and for abnormality diagnosis. The drift detection circuit 2 performs an abnormality diagnosis in the position signal change detection circuit 2A using the representative position signal S3. The position signal change detection circuit 2A outputs a drift detection output signal S5 when the representative position signal S3 changes more than an allowable value in the OFF state of the drive command S4. However, the position signal change detection circuit 2A outputs the drive command S4
Is a non-permission signal, the change in the position signal is detected only when the drive command S4 is in the OFF state.

[0004]

In FIG. 4, a deviation may occur between the A-system position signal S1 and the B-system position signal S2 due to detector accuracy or the like. When a representative position signal S3 used by the position signal switching circuit 1 is applied by a signal switching signal S6 to a case where the deviation is equal to or greater than an allowable value preset in the position signal change detection circuit 2A, a drive command S4 is output. If not, a drift detection signal S5 is output in order to detect a change in the representative position signal S3 in the position signal change detection circuit 2A. As a result, even though no drift has actually occurred, by switching the position signal, the representative position signal S3 changes, so that the drift is detected and an alarm is issued to the operator. . As described above, drift is an abnormal operation of the control rod, and when a drift alarm occurs, the operator monitors the plant condition,
It is necessary to take appropriate measures promptly. Therefore, erroneously detecting the drift by switching the position signals as described above and generating an excessive alarm places a heavy burden on the operator. SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to prevent erroneous detection of drift when switching multiplexed control rod position signals.

[0005]

In order to achieve the above object, the present invention is directed to a control rod position for detecting a number of control rods disposed in a nuclear reactor. In the detection device, a plurality of multiplexed position signals of the control rods in the reactor and a position signal selection signal for instructing which position signal to select among these position signals are input. Signal selection means for selecting and outputting a position signal corresponding to the position signal selection signal , and at least one of a drive signal indicating that the control rod is being driven and the position signal selection signal. Signal change non-permission signal is turned on when the signal change is not input, and the signal change non-permission signal is turned off when no signal is input. Output from the selection means When the rate of change of the position signal is not detected and the signal change disable signal is OFF, the rate of change of the position signal output from the signal selecting means is detected. Signal change detecting means for outputting an abnormal signal. A control rod position detecting device comprising:

According to a second aspect of the present invention, there is provided a control rod position detecting apparatus for detecting a position of a large number of control rods in a nuclear reactor, wherein the control in the nuclear reactor is performed. A plurality of multiplexed position signals of the rod and a position signal selection signal for instructing which of the position signals are to be selected are input, and a position signal corresponding to the position signal selection signal is input. Signal selection means for selecting and outputting, and signal selection output means for outputting a signal indicating that the position signal selection signal is ON for a predetermined time after the position signal selection signal is output and selecting the position signal; When at least one of the drive signal indicating that the control rod is being driven and the signal from the signal selection output means is input, the signal change disable signal is turned ON, and when the signal is not input, the signal change disable signal is turned ON. Signal change determining means for turning off the non-permission signal; and detecting the change rate of the position signal output from the signal selection means when the signal change non-permission signal is on, Signal change detecting means for detecting a rate of change of the position signal output from the signal selecting means when the signal is OFF, and outputting an abnormal signal when the rate of change is out of an allowable value. I do.

[0007]

According to the first aspect of the present invention, the position signal output from the signal selection means to the signal change detection means when the control rod is being driven or when the multiplexed position signal is selected by the signal selection means. If the control rod is not driven or the multiplexed position signal is not selected by the signal selection means, the rate of change of the position signal output from the signal selection means is not detected. Is detected, and an abnormal signal is output when the change rate deviates from the allowable range.

According to the second aspect of the present invention, when the multiplexed position signal is selected by the signal selection means, the position signal output from the signal selection means is continuously outputted for a predetermined time from the time of the selection. Does not detect the change rate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control rod position detecting device according to the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a control rod position detecting device of the present embodiment. The position signal switching circuit 1 fetches the A-system position signal S1 and the B-system position signal S2 of the control rod duplexed into the A-system and the B-system, and receives the A-system position signal S1 according to the position signal switching signal S6. Alternatively, it switches to and selects one of the B-system position signals S2 and outputs it as the representative position signal S3.

The drift detection circuit 20 comprises a position signal switching detection circuit 21, an OR circuit 22, and a position signal change detection circuit 2A. The position signal switching detection circuit 21 outputs the signal switching detection signal S7 for a predetermined time only when the position signal switching signal S6 is ON (when switching to the position signal is performed by the position signal switching circuit 1).

The OR circuit 22 outputs a signal change disable signal S8 when the drive command S4 or the signal switching detection signal S7 is input. The position signal change detection circuit 2A does not detect the drift of the representative position signal S3 while the signal change disable signal S8 is being output from the OR circuit 22, and outputs the signal change disable signal S8 from the OR circuit 22. While not being performed, the drift of the representative position signal S3 is detected, and if it is out of the allowable range, the drift detection output signal S5 is output.

Then, based on the drift detection output signal S5, the operator is notified of the abnormality by alarm means (not shown). Next, the operation of this embodiment will be described.

Position signal switching circuit 1 during control rod driving
Is operated, the OR command is sent to the OR circuit 22.
Is input, the drift detection of the input representative position signal S3 is not performed because the position signal change detection circuit 2A does not function by the signal change disable signal S8 from the OR circuit 22.

When the position signal switching circuit 1 is operated while the control rod driving is stopped, the signal change detection signal S7 is input to the OR circuit 22, so that the signal change disable signal from the OR circuit 22 is output. By S8, the position signal change detection circuit 2
Since A does not function, the drift detection of the input representative position signal S3 is not performed.

As described above, the drift of the representative position signal S3 can be detected only when the control rod drive and the position signal switching are not performed, so that unnecessary warning to the operator due to the conventional unnecessary drift detection is prevented. can do.

In this embodiment, when the position signal switching signal S6 is output from the position signal switching circuit 21, the signal is continuously output as a signal switching detection signal S7 for a predetermined time from that point in time, thereby detecting the position signal change during that time. Although the circuit 2A does not detect the drift of the representative position signal S3, for example, when a digital signal is used, the position signal switching detection circuit 21 The representative position signal S is supplied to the position signal change detection circuit 2A.
If the time difference between the time until the signal 3 is input and the signal change detection disable signal S8 input to the position signal change detection circuit 2A can be ignored, the output of the signal switching detection signal S7 is set to the position. The signal switching detection circuit 21 may output the signal when the position signal switching signal S6 is input.

In this embodiment, an example has been described in which the drift is erroneously detected due to the change of the representative position signal S3 due to the switching of the duplicated position signal. However, as shown in FIG. The control device that generates the representative position signal S3 can also prevent erroneous drift detection. Further, as a method of generating the representative position signal S3, even when outputting an average value or an intermediate value of all the signals or a part of the position signals as shown in FIG. Is input to the signal switching detection circuit 21 to detect a change in the position signal switching state, whereby erroneous diagnosis of drift can be prevented.

[0018]

According to the present invention, in a control rod position detecting device in which position signals are multiplexed, erroneous detection of a drift even if the position signals are switched when a deviation occurs between position signals in a multiplexed manner. Because there is no alarm, the burden on the operator due to the occurrence of an excessive alarm can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a control rod position detecting device according to a first embodiment.

FIG. 2 is a configuration diagram of a control rod position detecting device according to a second embodiment.

FIG. 3 is a configuration diagram of a control rod position detecting device according to a third embodiment.

FIG. 4 is a configuration diagram of a conventional control rod position detecting device.

[Explanation of symbols]

1: Position signal switching circuit, 2, 20: Drift detection circuit, 2
A: position signal change detection circuit, 21: position signal switching detection circuit, S1: A system position signal, S2: B system position signal, S3 ...
Representative position signal, S4: drive command, S5: drift detection output signal, S6: signal switching signal, S7: signal switching detection signal

Claims (2)

(57) [Claims] 1. A control rod position detecting device for detecting a position in a nuclear reactor of a large number of control rods disposed in the nuclear reactor, wherein a plurality of multiplexed control rods in the nuclear reactor are provided. A signal selector for inputting a position signal and a position signal selection signal instructing which of the position signals is to be selected, and selecting and outputting a position signal corresponding to the position signal selection signal; When at least one of the drive signal indicating that the control rod is driven and the position signal selection signal is input, the signal change disable signal is turned ON, and when no signal is input, no signal change Signal change determination means for turning off the permission signal; and detecting the rate of change of the position signal output from the signal selection means when the signal change non-permission signal is on, and in the case of And a signal change detecting means for detecting a change rate of the position signal output from the signal selecting means and outputting an abnormal signal when the change rate deviates from an allowable value. Position detection device. 2. A control rod position detecting device for detecting a position in a nuclear reactor of a large number of control rods disposed in the nuclear reactor, wherein a plurality of multiplexed control rods in the nuclear reactor are provided. A signal selector for inputting a position signal and a position signal selection signal instructing which of the position signals is to be selected, and selecting and outputting a position signal corresponding to the position signal selection signal; After the position signal selection signal is output and the position signal is selected, a signal selection output unit that outputs a signal indicating that the position signal selection signal is ON for a predetermined time; and the control rod is driven. The signal change non-permission signal is turned on when at least one of the drive signal and the signal from the signal selection output means is input, and the signal change non-permission signal is turned off when no signal is input.
A signal change determining unit that does not detect the rate of change of the position signal output from the signal selecting unit when the signal change non-permission signal is ON; Control rod position detecting means for detecting a change rate of a position signal output from the signal selecting means, and outputting an abnormal signal when the change rate deviates from an allowable value. Detection device.