KR101250749B1 - Method for measuring drop time of control rod utilizing an apparatus for monitoring coil current of rod control system - Google Patents

Abstract

The present invention relates to a control rod control system coil current monitoring device and a control rod fall time measurement method using the same, and to systematically manage and acquire the current waveform flowing in the control rod coil in real time during the operation of the power plant in the control rod control system and failure immediately when a failure occurs Provides a control rod control system coil current monitoring device capable of locating the position, and drops the control rod using the control rod control system coil current monitoring device that can easily carry out the test and eliminate the risks and difficulties of workers during the control rod drop test. It relates to a time measurement method.
A nuclear power plant having a control rod coil for controlling a control rod for nuclear power generation of the present invention, comprising: a power control unit for outputting a driving signal for driving the control rod to the control rod coil; A control rod coil including a lifting coil, a moving coil, and a stop coil installed around the control rod; A shunt resistor installed between the control rod coil and the power control box to measure a voltage; A current sensor installed between the control rod coil and the power control box to measure a current flowing through the control rod coil; A signal processing device for amplifying or filtering the voltage of the current or the shunt resistor by the current sensor; A signal acquisition controller for controlling a signal received by the signal processing device and transmitting the signal to a coil current monitoring analyzer; And a coil current monitoring analyzer electrically isolated from the power control box and receiving and analyzing a current signal flowing through the coil through the current sensor through a signal processing device and a signal acquisition controller. .
The control rod drop time measurement method using the control rod control system coil current monitoring device, the method comprising: installing a voltage measuring unit on a shunt resistance of a stop coil which maintains the control rod at a predetermined position; Drawing the control rod to the top using the control rod coil; A control rod holding step of supplying and maintaining a holding current to the control rod drawn out to the top; Blocking the holding current to drop the control rod; Measuring a time from a time point at which the voltage measured by the voltage measurer decreases to a peak point which increases again; .

Description

METHOD FOR MEASURING DROP TIME OF CONTROL ROD UTILIZING AN APPARATUS FOR MONITORING COIL CURRENT OF ROD CONTROL SYSTEM}

The present invention relates to a control rod control system coil current monitoring device and a control rod fall time measurement method using the same, and more specifically, control rod control system coil current monitoring that can systematically manage the current of the coils installed around the control rod in real time Apparatus and a control rod fall time measurement method that can be used to measure the control rod fall time using a safe and simple method.

Nuclear power is basically a nuclear fission reaction in the reactor to generate steam by using the heat energy generated at this time to drive the turbine to supply electricity. In order to control the fission reaction in such a reactor, a number of control rods are installed. The control rod is made of stainless steel or aluminum coated with boron, cadmium, hafnium and the like, which easily absorb thermal neutrons for mediating fission reactions. When the control rod is placed in the core, thermal neutrons are absorbed and the reaction temperature of the furnace is lowered. On the contrary, when the control rod is removed, the furnace is responsive.

1 is a configuration diagram of a control rod driving system according to the prior art, and includes an electric power box 10, an electronic card 20, a control rod 30, and a main controller 40 as shown.

A plurality of electronic cards 20 are connected to the power box 10. In addition, the electronic card 20 transmits and receives various signals with the power box 10 and flows an appropriate current from the power box 10 to the control rod 30 according to the signal of the electronic card 20. A plurality of coils are installed around the control rod 30 to move the control rod 30 up and down by passing a current through the coil. In addition, the main control unit 40 transmits a control signal to the power box 10, the power box 10 receives the control signal of the main control unit to apply a driving current to the control rod 30.

In nuclear power generation, safety is a top priority, so if a failure occurs in the control rod control system, the operation must be stopped and the cause of the failure must be found and repaired immediately. The existing control rod control system emits a beep when a failure occurs, but it is difficult to find out where the failure occurred, so much time was required to find the cause of the failure.

On the other hand, in accordance with the procedures set out in the Nuclear Safety Regulation, the time required for the free fall of the control rod immediately before the critical point of the reactor to the entrance of the braking arc located below the reactor core shall be within 3.3 seconds. To this end, a control rod drop test is carried out. The test methods generally include a method of directly measuring a time at a control rod position indicating device and a method of estimating a drop time by measuring a voltage induced by a moving coil when the control rod is dropped.

The first method involves the difficulty of the operator entering the reactor containment building and the measurement of the voltage induced by the other operator on the voltmeter by the switchboard.

On the other hand, in the second method, the operator does not have to enter the reactor containment building directly, but it is difficult to disassemble all the wires connected to the mobile coil in the power control box to measure the voltage induced by the mobile coil. In the control rod drop test, unwinding all 104 terminals of 52 control rods and creating test points is a very dangerous and difficult task. In particular, there is a risk of electric shock from accidental touches because current flows through the coil which is not used for measurement in the process of dismantling complicated wiring. In addition, when making the test point, in order to stop the control rod at the top, a holding current of about 4 to 5 ampere is applied to the stop coil, which may cause an electric shock.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to obtain a current waveform flowing in a control rod coil in real time using a current sensor and a shunt resistor during operation of a power plant in a control rod control system. The present invention provides a control rod control system coil current monitoring device.

The second object of the present invention is to control the control rod falling time by measuring the voltage of the shunt resistance connected to the stop coil of the control rod control system coil current monitoring device using the control rod control system coil current monitoring device. To provide a measuring method.

According to an aspect of the present invention, there is provided a nuclear power plant including a control rod coil for controlling a control rod for nuclear power generation, the power control unit outputting a driving signal for driving the control rod to the control rod coil; A control rod coil including a lifting coil, a moving coil, and a stop coil installed around the control rod; A shunt resistor installed between the control rod coil and the power control box to measure a voltage; A current sensor installed between the control rod coil and the power control box to measure a current flowing through the control rod coil; A signal processing device for amplifying or filtering the voltage of the current or the shunt resistor by the current sensor; A signal acquisition controller for controlling a signal received by the signal processing device and transmitting the signal to a coil current monitoring analyzer; A coil current monitoring analyzer electrically isolated from the power control box to receive and analyze a current signal flowing through the coil through the current sensor through a signal processing device and a signal acquisition controller; Characterized in that it comprises a.

Also preferably, the current sensor is a shunt resistor fed back to the control circuit of the power box.

In addition, the coil current monitoring analyzer is characterized in that the normal range of the current flowing in the control rod coil is stored in advance, and determines whether the current value measured by the current sensor is within the normal range.

The control rod drop time measurement method using a control rod control system coil current monitoring device, the method comprising: installing a voltage measuring unit on a shunt resistance of a stop coil which maintains the control rod at a predetermined position; Drawing the control rod to the top using the control rod coil; A control rod holding step of supplying and maintaining a holding current to the control rod drawn out to the top; Blocking the holding current to drop the control rod; Measuring a time from a time point at which the voltage measured by the voltage measurer decreases to a peak point which increases again; .

According to the present invention as described above, there is an effect that can be systematically managed by obtaining the current waveform flowing in the control rod coil in real time while the power plant is operating.

In addition, according to the present invention, by measuring the voltage of the stationary coil, not the moving coil of the control rod, there is an effect that the operator can easily perform the drop test without the need to disassemble the wiring without entering the reactor containment building during the control rod drop test. .

1 is a block diagram of a control rod drive system according to the prior art.
2 is a block diagram of a control rod control system coil current monitoring apparatus according to an embodiment of the present invention.
3 is a circuit diagram illustrating a voltage measuring circuit of a shunt resistor according to an embodiment of the present invention.
4 is a flow chart illustrating a method for measuring a control rod drop time using a control rod control system coil current monitoring apparatus according to an exemplary embodiment of the present invention.
5 is a conceptual diagram showing the configuration of a control rod drop test according to an embodiment of the present invention.
Figure 6 is a graph showing the current waveform of the stop coil appearing in the control rod drop test according to an embodiment of the present invention.
Figure 7 is a graph showing the current waveform of the moving coil appearing in the control rod drop test according to an embodiment of the present invention.

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

A control rod control system coil current monitoring apparatus according to an embodiment of the present invention will be described with reference to FIGS. 2 to 3 as follows.

2 is a block diagram of a control rod control system coil current monitoring apparatus according to an embodiment of the present invention, as shown in the power control box 100, control rod coil 200, shunt resistor 300, current sensor 400 ), A signal processor 500, a signal acquisition controller 600, and a coil current monitoring analyzer 700.

The power control box 100 applies a current for driving the control rod (R) to the control rod coil (200). The power control box 100 receives the operation signal from the main control unit to flow the current to the raising coil 210, the stop coil 230 and the moving coil 220 in a predetermined order to the control rod (R) Step down or up. In addition, when the control rod (R) reaches a constant position by passing a current to the stop coil 230 to stop the control rod (R).

The control rod coil 200 is installed around the control rod (R) and moves the control rod (R) up and down and includes a lifting coil (210), a stop coil (230) and a moving coil (220). The lifting coil 210 and the moving coil 220 move the control rod R up and down, and the stop coil 230 is a coil for stopping the control rod R at a predetermined position. And the current flowing through the stop coil 230 in a state in which the current of the moving coil 220 is blocked, the control rod R drops downward by gravity.

The shunt resistor 300 includes a voltage measuring unit 310 for measuring the voltage of the shunt resistor 300 and transmits the measured voltage as an input signal to the signal processor 500. In addition, the current of the control rod coil can be calculated indirectly from the voltage of the shunt resistor. As shown in FIG. 3, the voltage measuring unit 310 is insulated from the voltage measuring unit 310 through an isolation amplifier of the voltage measuring unit 310 appearing on the shunt resistor 300.

The current sensor 400 is for measuring the current flowing in the control rod coil 200 is a voltage in proportion to the current applied to the control rod drive (CRDM) coil in a magnetic induction method using a Hall sensor.

Also preferably, the current sensor 400 adjusts the current and voltage ratio by utilizing the mechanism part and the electronic part of the ACTM sensor used in a standard power plant as an indirect current sensor.

And, preferably, the current sensor 400 has a hinge structure when the interference between the cables can be minimized when installed in the cable without applying excessive force to the PCB of the sensor assembly.

The signal processor 500 operates as a low pass filter and amplifies the waveform according to the voltage applied to the shunt resistor 300 and the current measured by the current sensor 400. Since the coil current monitoring analyzer 700 should not affect the power control box 100 in an electrical signal manner, the signal processor 500 isolates the coil current monitoring analyzer 700 from the power control box 100. .

The signal acquisition controller 600 processes the acquired signal and transmits it to the coil current monitoring analyzer 700, and includes a controller, a chassis, and a date acquisition (DAQ) card. Preferably, the chassis consists of a compact PCI chassis and has five slots. The electronic card receives various signals and transmits them to the coil current monitoring analyzer 700.

The coil current monitoring analyzer 700 stores and analyzes data acquired from the signal acquisition controller 600. The coil current monitoring analyzer 700 performs a standby mode, a setting mode, a monitoring mode, and an analysis mode.

In addition, the standby mode is a temporary operation state is a mode that operates at the time of initial equipment startup, setting value change and other necessary, and automatically enters the standby mode when the power is turned on and does not perform data acquisition.

In addition, the setting mode sets the control rod group connected to the DAQ card module. One control rod (R) group consists of 52 control rods (R), of which four control rods (R) constitute one subgroup. In the configuration mode, the sampling rate of the DAQ card module is set. In addition, in the setting mode, the input signal effective range reference value of the control rod coil 200 and the control rod coil 200 current abnormal reference value are set and changed. In addition, the on / off of the alarm can be set accordingly.

In addition, the monitoring mode acquires a signal for all the control rod drive device (CRDM) to determine whether the normal drive or not. All input signals input to the coil current monitoring analyzer 700 are continuously acquired in a designated sampling period and stored in a temporary buffer. Therefore, whether the abnormality is determined by the control rod (R) drive unit is determined by monitoring the change trend of the coil acquisition current value of each control rod drive unit and comparing it with the reference set value. At this time, the data is automatically stored before and after the time when the user departs from the desired setting value.

In addition, the continuous mode is performed at the request of the user, and is for real-time observation and storage of waveforms during periodic inspection and test. Waveform monitoring is performed for up to four control rods (R) and continuously outputs each coil waveform of the specified control rod (R). The output waveform can be changed at a specified sampling period.

The analysis mode is a mode in which data stored in advance is analyzed in detail. Basically, there are waveform display, scrolling, magnification and superimposing functions. It also provides waveform data editing function. In the analysis mode, the current reference waveform is set and stored, and when the control rod R is driven, it is determined whether it is within the normal range and judges whether it is normal or abnormal.

The control rod control system coil current monitoring device can grasp the problems occurring in the control rod (R) in real time and greatly contribute to the safe operation of the power plant. Accurate troubleshooting is possible.

The acquired current waveform is transmitted to the computer connected online in real time, and the data can be systematically managed by these data, so that the cause of the problem can be traced through grasping the past history.

Hereinafter, a method of measuring the control rod R drop time by measuring the control rod coil 200 current will be described. The control rod (R) drop time measurement test of a nuclear power plant periodically checks whether the drop response of the control rod (R) according to the reactor emergency stop command is within the limits of the guidelines. It is an important test to confirm.

4 is a flowchart illustrating a control rod drop time measuring method using a control rod control system coil current monitoring apparatus according to an embodiment of the present invention. As shown, the control rod (R) drop time measuring method is a control rod control system coil current monitoring method. In the control rod falling time measurement method using a device, the step of installing the voltage measuring unit 310 to the shunt resistor 300 connected to the stop coil 230 to maintain the control rod (R) at a predetermined position (S100), Using the control rod coil 200 to draw the control rod (R) to the top (S200), the control rod holding step (S300) for supplying and maintaining a holding current to the control rod (R) drawn to the top end, blocking the holding current And dropping the control rod R (S400) and measuring the time from the time point at which the voltage is decreased from the voltage measuring unit 310 to the peak point increasing again (S500).

Specifically, the step S100 to S500 will be described, the voltage measuring unit 310 is installed in the shunt resistor 300 connected to the stop coil 230 for maintaining the control rod (R) at a predetermined position (S100).

In addition, the control rod (R) is drawn to the top by applying a voltage to the lifting coil 210 for the drop test (S200).

In addition, in the state in which the control rod R is drawn out to the top, a holding current is applied to the stop coil 220 to maintain the stop state (S300). In this state, when the current of the lifting coil 210 and the moving coil 220 is cut off, the control rod R is in a state immediately before falling.

In addition, the control rod (R) is dropped by blocking the holding current supplied to the stop coil 220 (S400), and the peak point that increases again from the time point at which the voltage of the shunt resistor is decreased by using the voltage measuring unit 310. Measure the time until (S500).

Then, when the control rod (R) falls, the current waveform flowing through the stop coil (230) by the control rod control system coil current monitoring device is recorded. In addition, the control rod control system coil current monitoring device may be mounted on the lifting coil 210 and the moving coil 220 in addition to the stop coil 230. And, the current waveform of the stop coil 230 with time is as shown in FIG.

As shown in FIGS. 5 and 6, when the holding current of the stop coil 230 is cut off, the current decreases exponentially due to the self-induction phenomenon of the stop coil 230. At this time, the electromagnetic induction into the coil due to the movement of the control rod R itself is small enough to be ignored. When the control rod (R) falls, the induction voltage is also measured in the lifting coil (210) or the moving coil (220), but this is mainly due to the mutual induction (mutual induction) phenomenon by the stop coil (230). The effect of dropping is not measured or negligible.

That is, the voltage induced by the raising coil 210 or the moving coil 220 may be represented by E = -M * (dA / dt). Here, E is the electromotive force induced in the raising coil 210 or the moving coil 220, M is the mutual induction coefficient, A is the current flowing through the stop coil 230. This may be confirmed in that the shape of the graph obtained by differentiating the current of the stop coil 230 with time shown in FIG. 6 coincides with the shape of the voltage graph induced in the moving coil 220 of FIG. 7. Therefore, the method of measuring the drop time of the control rod R by analyzing the graph of the voltage induced in the moving coil 220 is an indirect method as it is derived from the stop coil 230.

On the other hand, as shown in Figure 6, the measurement method through the current, there is a peak point (F) from which the current suddenly protrudes, which is a phenomenon that occurs when the control rod (R) collides with the braking arc (RH) control rod (R) When the collision strikes the braking arc (RH), the contact causes a sudden change in impedance, and as a result, an instantaneous current is induced in the stop coil 220. Therefore, by first calculating the time t between the control rod (R) drop time (s) and the peak point (f), the control rod (R) fall time can be measured.

However, unlike the measurement method using the current sensor, the control rod fall time measurement using the voltage of the shunt resistor does not need to dismantle the wiring of the moving coil 220 or the raising coil 210, thus saving preparation time, and due to incorrect wiring. It is possible to prevent safety accidents such as electric shocks without fear of equipment damage and at the same time, it is possible to measure the control rod drop time more efficiently and accurately than before.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It will be appreciated by those skilled in the art that numerous changes and modifications may be made without departing from the invention. Accordingly, all such appropriate modifications and changes, and equivalents thereof, should be regarded as within the scope of the present invention.

10: power box 20: electronic card
30: control rod 40: main fisherman
100: power control box 200: control rod coil
210: up coil 220: moving coil
230: stop coil 300: shunt resistance
400: current sensor 500: signal processor
600: signal acquisition controller 700: coil current monitoring analyzer
R: Control rod RH: Braking arc

Claims (4)

delete delete delete In the control rod drop time measurement method using a control rod coil including a lifting coil, a moving coil and a stop coil installed around the control rod, and a control rod control system coil current monitoring device,
Installing a voltage measurement unit on a shunt resistance of the stop coil which maintains the control rod at a predetermined position;
Drawing the control rod to the top using the control rod coil;
A control rod holding step of supplying and maintaining a holding current to the control rod drawn out to the top;
Blocking the holding current to drop the control rod; And
Calculating a time from a time point at which the voltage measured by the voltage measurer decreases to a peak point that increases again, extracting an inflection point and extracting a minimum point after the rise to obtain a fall time from the time between the minimum points; Control rod drop time measurement method using a control rod control system coil current monitoring device, characterized in that consisting of.

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