KR100650294B1 - Apparatus for preventing unwanted high voltage applied to control rod driving system in nuclear power plant and Method thereof - Google Patents

Abstract

The present invention relates to a method and an apparatus for preventing accidentally falling of a control rod in a nuclear power plant. More specifically, the control rod drive device, a power control device for supplying a current to the control rod drive device, and A high voltage prevention device of a control rod control system for use in a control rod control system including a logic unit for outputting a firing pulse signal for controlling an output, the apparatus comprising: a substitution for outputting a replacement signal capable of replacing the firing pulse signal output from the logic unit; Signal generator; A main signal monitor for monitoring an abnormality of the firing pulse signal output from the logic device; And a signal selection circuit for supplying a substitute signal to the power control device in place of the firing pulse signal when an abnormality of the firing pulse signal is detected from the main signal monitoring device. will be.

According to the present invention, unlike the conventional technique of firing all three-phase SCRs of the upper tong winding of the SCR control signal in a high voltage state, the SCR is not fired in a high voltage state. It can solve the disadvantage that can cause physical damage.

Nuclear power plant, control rod, drop, winding, damage, high voltage

Description

Apparatus for preventing unwanted high voltage applied to control rod driving system in nuclear power plant and Method

1 is a diagram illustrating a power control system of a control rod control system for supplying power to a conventional four-wound control rod drive device;

2 is a diagram illustrating a power control system of a control rod control system for supplying power to a control rod driving apparatus to which the present invention is applied;

3 is a block diagram showing the configuration of an alternative signal isolator of the present invention.

4 is a flow chart illustrating a method of the present invention.

* Explanation of symbols for the main parts of the drawings

110 Control rod drive 111 Upper lifting winding

112 Upper tong winding 113 Lower towing winding

114 Lower tong winding 120 Sub-group power control circuit

121 Zero Detector 122 SCR Calling Circuit

123 SCR 130 Subgroup Logic Circuit

131 Voltage Control Circuit 132 Voltage Selection Circuit

133 Control Rod Controller 140 Maintenance Power Supply

141 Manual Power Control Panel 142 Power Supply

150 System Controller 160 Current Detector

170 Transfer Switch 180 System Power

181, 182 Circuit Breaker 210 Alternate Signal Generator

220 Alternate Signal Isolator 230 Alternate Signal Monitor

240 Main signal monitor 250 Signal selection circuit

260 Alarm 211 Zero Detector

212 Voltage Control Circuit 221 LED

222 Phototransistor

The present invention is an abnormal power supply of high voltage to the control rod drive device upper forefinger holding the control rod by the abnormal supply of the Silicon Controlled rectifier (SCR) control signal due to a single failure of the control circuit in the control rod control system in a nuclear power plant. The present invention relates to an apparatus and a method for supplying and damaging a winding of a control rod drive and thereby preventing the control rod drop.

In the nuclear power plant, the control rod control system controls the output of the reactor by inserting or withdrawing the control rod which is the neutron absorber according to the manual control command of the operator and the automatic control command of the reactor power control system during the operation of the power plant. In order to relieve the output imbalance between the reactor and the turbine generator caused by the failure of the reactor, the control rod suddenly decelerates the reactor output by freely dropping a predetermined control rod into the reactor core, and all the control rods according to the reactor stop signal of the reactor protection system. Free fall into the reactor core to safely stop the reactor.

In the PWR (Pressurized Water Reactor) nuclear power plant, the control rod control system supplies a predetermined magnitude of DC current to the tongs and the up winding of the control rod drive device according to an electrical signal in a predetermined order, and is discharged by the winding. It is used to maintain, insert or withdraw the control rod by using magnetic force to operate the internal mechanical drive.

The control rod driving device is divided into three winding type and four winding type according to the structure and operation method, and the four winding type is the three winding type, and there is one additional winding winding.

During operation of the power plant, most control rods are drawn out as high as possible in order to secure a stop margin and remain in a stopped state. In this state, a constant amount of holding current is supplied to the tong winding. That is, in the state in which the control rod is not moving and is stopped, a constant DC current is supplied to the tong winding and the control rod is kept in the stopped state.

The control rods remain mostly in a stopped state for one cycle of operation for about 18 months, and if the power supply is interrupted due to a single failure in the control circuit that powers the control rod drive, the control rod does not maintain its current position. Free fall into the reactor core.

For example, a silicon controlled rectifier (SCR) that supplies a DC voltage to each winding constituting a control rod drive device in accordance with a circuit breaker of a power control system, a protective fuse, and a sequence control signal that supplies current to a forefinger winding during operation of a power plant. Single components such as switching devices, diodes, connectors, etc. may be uninterrupted or interrupted, and malfunctions or failures may occur in the related electronic circuits that control the SCR.

If this problem occurs, the holding current supplied to the tong winding holding the control rods is momentarily interrupted and the associated control rods (one or one subgroup of four control rods) can be inserted into the reactor core.

If one control rod or one subgroup of control rods accidentally falls and is inserted into the reactor core during the normal power operation of the nuclear power plant, the output distribution in the core will change, and the control rod will be changed to compensate for the output loss of the dropped portion. Regional reactor output will rise, resulting in fuel damage in the rising portion of the output.

In order to prevent such abnormal results, nuclear power distribution equipment is always monitored by nuclear instrumentation. If a change in the output distribution of the reactor due to a sudden drop of the control rods is detected, the safety of the rest of the control rods is also blocked by the reactor protection system, and the control rods are all free-falling and inserted into the core. Once all control rods are inserted into the core, the reactor is safely shut down and the turbine generator can no longer produce power.

Therefore, if an unnecessary control rod drop occurs due to a failure of a part of the system during the normal power operation of the nuclear power plant, power generation is interrupted, which causes a large economic loss.

In order to prevent the occurrence of such economic losses, the research on the technology and apparatus for preventing the unnecessary control rod fall as described above are continuously made.

1 illustrates a power control system of a control rod control system for supplying power to a conventional four-wound control rod driving apparatus, and employs a fault detection electronic circuit to minimize unnecessary drop of the control rod and protect the control rod driving winding, and tongs If an abnormality is detected in the current of the winding, it supplies the holding current to the other tong winding and provides the abnormal alarm. Specifically, it is as follows.

The three-phase 240V AC voltage supplied from the system power supply 180 is a zero point detector 121 of the subgroup power control circuit 120 for detecting a point where the voltage is 0V in the waveform of the AC voltage to make an SCR firing pulse. Input to the voltage control circuit 131 via the ().

The voltage control circuit 131 generates an SCR firing pulse capable of generating a high voltage used to drive the control rod drive device and a low voltage used to maintain the driving state using the input of the zero detector.

The control rod controller 133 determines whether to provide a high driving voltage, a low voltage for maintenance, or to cut off the power for each of the four windings of the control rod driving apparatus 110 according to the control of the system controller 150. The control signal is sequentially output to the voltage selection circuit 132 according to the operation timetable.

The voltage selection circuit 132 determines and provides a firing pulse signal corresponding to the supply voltage of the SCR firing circuit 122 according to the sequence control signal of the control rod controller 133.

The SCR firing circuit 122 arcs the SCR 123 using the signal output from the voltage selection circuit 132, and the SCR 123 is the upper raising winding 111 of the control rod drive device 110, the upper clamp winding ( 112), a predetermined direct current is supplied to each of the lower raising winding 113 and the lower tong winding 114.

If a problem occurs in a circuit that transmits a signal to the subgroup power control circuit 120, and thus a signal is not transmitted from the voltage selection circuit 132 to the SCR firing circuit 122, the SCR firing circuit 122 is unconditional. By firing the SCR 123 so that the high voltage is output from the SCR 123 to the upper tong winding, it prevents the control rod from falling and generates an alarm.

The cause of the failure that the abnormal power of the high voltage is continuously supplied is the loss of the zero detector control power due to the burnout of the relay power supply fuse for the zero detector 121 control power supply, the burnout of the logic power supply fuse for the logic power supply of the voltage selection circuit 132, etc. The voltage selection circuit 132 may lose the logic power, the control rod controller 133, and the like. When such a problem occurs, the voltage selection circuit loses the function of generating the SCR control signal, and continues to generate a signal for supplying a high voltage DC power only to the upper tong winding and generates an emergency alarm.

When the alarm occurs, the operator checks the abnormal subgroup, and operates the maintenance power manual control panel 141 of the maintenance power supply 140 installed in the system cabinet to connect the power supply 142 and the corresponding clamp winding ( 170 is connected to supply the alternative power to the corresponding tong winding, stops the operation of the abnormal subgroup power control circuit 120, and performs the cause investigation and repair. It is not possible to withdraw or insert a control rod while a particular subgroup is switched to an alternative power source. During the maintenance period the control rod remains in its current position.

However, if the operator's action is delayed and exposed to high voltage for a long time, the winding may be physically damaged, and ultimately, the control rod may fall due to the stop of supply of the holding current due to the physical damage of the winding. .

In addition, if the winding of the control rod drive device is damaged, it is impossible to drive the control rod, so it must be replaced with a normal winding, and the nuclear reactor stops and the radiation exposure of the operator is inevitable and takes a lot of time and money.

In order to solve the above problems, the present invention improves the control rod control system for controlling the position of the control rod to control the output of the reactor in a nuclear power plant, so that if a failure occurs that causes all three-phase SCRs of the upper forefinger winding to high voltage, It aims to provide a system that can improve the economics of nuclear power plants by ensuring the stable operation of power plants by preventing the physical damage of the tongs winding and the falling of the control rods due to this, and reducing the cost of unplanned operation.

In order to solve the above problems, an object of the present invention is to provide a method for driving the above-described system.

In order to achieve the above object, the present invention provides a control rod drive device, a power control device for supplying current to the control rod drive device, and a logic device for outputting a firing pulse signal for controlling the output of the current from the power control device. A high voltage prevention device of a control rod control system for use in a control rod control system comprising: a replacement signal generator for outputting a replacement signal capable of replacing a firing pulse signal output from the logic device; A main signal monitor for monitoring an abnormality of the firing pulse signal output from the logic device; And a signal selection circuit for supplying the replacement signal to the power control device in place of the firing pulse signal when an abnormality of the firing pulse signal is detected from the main signal monitoring device. To provide.

The high voltage prevention device may further include an alternative signal isolator for isolating the alternative signal output from the alternative signal generator and supplying the alternative signal to the signal selection circuit.

The high voltage prevention device may further include an alarm for generating an alarm when an error occurs in the firing pulse signal from the main signal monitor.

The high voltage prevention device may further include: a replacement signal monitor configured to monitor an abnormality of the replacement signal output from the replacement signal generator; And an alarm for generating an alarm when the substitute signal monitor detects an abnormality of the substitute signal.

In addition, the substitute signal generator is a zero point detector for receiving a power supplied from the system power source to detect the point of the voltage 0V; And a voltage control circuit for outputting a pulse signal used as the replacement signal by using the output of the zero detector.

On the other hand, in order to achieve the above object, the present invention provides a control rod drive device, a power control device for supplying current to the control rod drive device, and a logic for outputting a firing pulse signal for controlling the output of the current from the power control device. CLAIMS 1. A method for preventing high voltage of a control rod control system for use in a control rod control system including a device, the method comprising: outputting a substitute signal capable of substituting a firing pulse signal output from the logic device; Monitoring for abnormality of the firing pulse signal output from the logic device; And if the abnormality of the firing pulse signal is detected, supplying the substitute signal to the power control device instead of the firing pulse signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing the configuration of a system of one preferred embodiment of the present invention.

The power control circuit 120 for each subgroup including the zero detector 121, the SCR call circuit 122, and the SCR 123, the voltage control circuit 131, the voltage selection circuit 132, and the control rod controller 133. Each of the sub-groups including the logic circuit 130, and four windings of the upper winding winding 111, the upper tong winding 112, the lower tong winding 113 and the lower tong winding 114 (Lift) control rod drive device 110 including three windings (not shown) including a winding, a moving latch winding, a stationary latch winding, a system controller 150 and a system power supply ( Since the description of 180 has already been made in the prior art, the following description focuses on the characteristic parts of the present invention.

Apparatus for preventing high voltage in the control rod drive device of the present invention is a substitute signal generator 210, substitute signal isolator 220, substitute signal monitor 230, main signal monitor 240, signal selection circuit 250 and It is configured to include an alarm 260.

The replacement signal generator 210 outputs a signal to replace the firing pulse signal (hereinafter, 'main signal') for controlling the SCR firing circuit 122 in the voltage selection circuit 132.

There may be various methods of generating a signal. For example, FIG. 2 includes a zero detector 211 and a voltage control circuit 212 having the same function as the existing zero detector 121 and the voltage control circuit 131 in the replacement signal generator 210 and replaced using the same. Generate a signal. In contrast to the conventional configuration, the voltage control circuit 131 uses the input of the zero detector 121 to generate the high voltage used to drive the control rod drive device and the low voltage used to maintain the driving state. Although outputting the SCR firing pulse, the voltage control circuit 212 in the replacement signal generator 210 is different in that it outputs only the SCR firing pulse for generating a low voltage used to maintain the driving state as a replacement signal.

In the present embodiment, only the alternative signal generator 210 of the type shown in FIG. 2 is illustrated, but another alternative signal generator 210 may be possible, as long as it can output a firing pulse for controlling the SCR firing circuit 122. Any form of circuit configuration is possible.

For example, in FIG. 2, the zero point detector 211 is directly supplied with power from the system power supply 180 to detect zero point, and the voltage control circuit 212 uses the output signal of the zero point detector 211 to control the SCR firing pulse. Although it is supposed to generate a, the signal output from the zero detector 121 may be directly input to the voltage control circuit 212 without having a separate zero detector in the alternative signal generator 210.

The replacement signal isolator 220 allows the replacement signal generated from the replacement signal generator 210 to be isolated from the subgroup power control circuit 120. This is to prevent the failure of the replacement signal generator 210 from affecting the subgroup.

There may be a number of ways to isolate the replacement signal through the replacement signal isolator 220. For example, a light isolation method such as illustrated in FIG. 3 may be used.

The replacement signal isolator 220 includes a light emitting diode 221 and an optical transistor 222 therein, and isolates the replacement signal using the light emitting diode 221 and the phototransistor 222 to be supplied to the subgroup power control circuit 120.

The replacement signal monitor 230 monitors whether the replacement signal outputted from the replacement signal generator 210 is abnormal through the replacement signal isolator 220. The replacement signal monitor 230 monitors an input pulse and outputs an alarm signal through the timeout and alarm 260 when a pulse is not generated for a predetermined time, that is, when a mono stable state continues for a predetermined time. Be sure to

Since the technology for determining whether the pulse is input belongs to the common sense to those skilled in the art, a detailed description thereof will be omitted.

The main signal monitor 240 monitors whether the main signal output from the voltage selection circuit 132 is abnormal. The main signal monitor 240 also determines whether the pulse is continuously input in the same manner as the alternative signal monitor 230, and if the pulse does not occur for a predetermined time, an alarm signal through the timeout and the alarm 260 is generated. .

The alarm 260 generates an alarm by receiving a signal for outputting an alarm signal from the substitute signal monitor 230 or the main signal monitor 240.

The signal selection circuit 250 selects a signal such that any one of a main signal output from the subgroup logic circuit 130 and a substitute signal generated from the substitute signal generator 210 is input to the SCR firing circuit 122. .

Specifically, the signal selection circuit 250 is generated in the replacement signal generator 210 when a signal indicating that an abnormality has occurred in the pulse signal output from the subgroup logic circuit 130 is input from the main signal monitor 240. The replacement signal is inputted to the SCR firing circuit 122.

 When a signal indicating an abnormality of a signal is input, a technique of switching a transmitted signal is a general technique for a person having ordinary knowledge in the technical field to which the present invention belongs, and thus a detailed description thereof will be omitted.

4 is a flow diagram illustrating a method of one embodiment of the present invention.

First, the replacement signal generator 210 generates a replacement signal that can replace it when an abnormality occurs in the main signal (401). Since the process of generating the replacement signal has already been described with reference to FIG. 2, a detailed description thereof will be omitted.

The substitute signal generated by the substitute signal generator 210 is optically isolated through the substitute signal isolator 220 (402), and is input to the substitute signal monitor 230 and the signal selection circuit 250 (403).

On the other hand, the main signal monitor 240 monitors the main signal output from the voltage selection circuit 132 to monitor whether or not the pulse is continuously output (411).

When the main signal monitor 240 determines that the main signal is abnormal (412), the main signal monitor 240 transmits a signal indicating that the main signal is abnormal to the signal selection circuit 250 and generates an alarm through the alarm 260. (413).

When the signal selection circuit 250 receives a signal indicating that an abnormality has occurred in the main signal from the main signal monitor 240, the signal selection circuit 250 uses the substitute signal generated by the substitute signal generator instead of the main signal to provide the firing pulse to the SCR firing circuit 122. If an abnormality does not occur in the main signal, it is supplied (414) and continues to be used as a firing pulse for supplying the main signal to the SCR firing circuit 122 (415).

On the other hand, when the replacement signal monitor 230 detects that an abnormality has occurred in the replacement signal generated by the replacement signal generator to notify the alarm 260 to output an alarm signal (not shown).

As described above, according to the present invention, unlike the conventional technology of all three-phase SCR of the upper tong winding of the SCR control signal lost to high voltage state, the SCR is not fired to the high voltage state, so the operator's action is delayed and the high voltage situation is long. This can solve the disadvantage of being exposed to physical damage of the windings.

In addition, it is possible to improve the economics of the nuclear power plant by ensuring a stable operation of the power plant by reducing the unplanned fall of the control rod and reducing the cost due to power generation interruption.

In addition, it is possible to minimize the preventive maintenance work and related costs for the control rod control system, which is excessively performed at each regular inspection due to the fear of sudden drop of the control rod due to a single failure of the control rod control system, and to reduce the mental burden of maintenance personnel. You can expect

Claims (10)

Control rod drive device 110, a power control device 120 for supplying a current to the control rod drive device, and a logic device 130 for outputting a firing pulse signal for controlling the output of the current from the power control device; In the high voltage prevention device of the control rod control system used in the control rod control system to A substitute signal generator 210 for outputting a substitute signal capable of replacing the firing pulse signal output from the logic device; A main signal monitor 240 for monitoring an abnormality of the firing pulse signal output from the logic device; And And a signal selection circuit 250 for supplying the replacement signal to the power control device instead of the firing pulse signal when an abnormality of the firing pulse signal is detected from the main signal monitor. Prevention device. The method of claim 1, wherein the high voltage prevention device And a replacement signal isolator (220) for isolating the replacement signal output from the replacement signal generator and supplying the replacement signal to the signal selection circuit. The method of claim 1, wherein the high voltage prevention device And an alarm (260) for generating an alarm when an error occurs in the firing pulse signal from the main signal monitor. The method of claim 1, wherein the high voltage prevention device A substitute signal monitor 230 for monitoring whether an alternative signal outputted from the substitute signal generator is abnormal; And And a warning device (260) for generating an alarm when the replacement signal monitor detects an abnormality of the replacement signal. The method of claim 1, wherein the replacement signal generator A zero detector 211 which receives power supplied from the system power and detects a point where the voltage is 0V; And And a voltage control circuit (212) for outputting a pulse signal used as the replacement signal by using the output of the zero detector. A control rod drive device 110, a power control device 120 for supplying a current to the control rod drive device, and a logic device 130 for outputting a firing pulse signal for controlling the output of the current from the power control device; In the high voltage prevention method of the control rod control system used in the control rod control system to Outputting a substitute signal capable of replacing the firing pulse signal output from the logic device; Monitoring for abnormality of the firing pulse signal output from the logic device; And And when the abnormality of the firing pulse signal is detected, supplying the substitute signal to the power control device instead of the firing pulse signal. The method of claim 6, wherein the high voltage prevention method Optically isolating the output replacement signal; and a high voltage preventing method of a control rod control system, further comprising. The method of claim 6, wherein the high voltage prevention method And generating an alarm when an error occurs in the firing pulse signal. The method of claim 6, wherein the high voltage prevention method Monitoring whether the substitute signal is abnormal; And And generating an alarm when an abnormality of the substitute signal is sensed. The method of claim 6, wherein the alternative signal output step Receiving a power supplied from a system power supply and detecting a point at which the voltage is 0V; And And outputting a pulse signal used as the replacement signal by using the detected result.

Images