JPH08136683A - Control rod stop controlling system - Google Patents

Abstract

PURPOSE: To make it possible to stop an induction electric motor for driving control rods in a short time by outputting brake-actuating signals from a controller during the operation of the control rods to stop it. CONSTITUTION: The output of control rod stop commands from a position control circuit 12 turns off a power supply breaker 13B of an induction electric motor controlling circuit 13 and allows a brake controlling circuit 14 to actuate a brake 15A and then, after the delay of a certain time by delay timer, start a brake 15B. In other words, the brake 15A with a high stopping operation torque lowers the rotary torque of an induction electric motor 7 beforehand, and then the brake 15B with a low stopping operation torque is actuated in a certain timing. Such staggered actions of the brakes 15A and 15B enables an efficient stop of the electric motor 7. After it stops, moreover, the brakes 15A and 15B keep control rods from moving.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control rod stop control system for a nuclear reactor installed in a nuclear power plant, for example.

[0002]

2. Description of the Related Art In the Advanced Nuclear Power Station (ABWR),
The operation of the control rod that controls output is performed by electric drive. The output control of the nuclear reactor is performed by the operation of this control rod. As one of the control requests, it is necessary to stop as soon as possible based on the operator's control rod stop request.

The operation of the control rods is performed based on the control rod operation procedure in response to an operation command from the control rod operation monitoring panel of the central control room. The operation of the control rod is performed by a step motor, and is operated by a pulse signal from the speed control circuit. The speed control of the step motor is performed by changing the frequency of the pulse current.

When the control rod is stopped, the speed control circuit reduces the rotation of the step motor. Therefore, a pulse signal having a small frequency is output to reduce the rotation speed. Then, when it finally stops, the holding brake operates. That is, the holding brakes do not operate simultaneously while the control rods are being driven, and do not act on the motor stop control. This holding brake is installed for the purpose of preventing the control rod from operating without permission after the motor is stopped.

As a technique related to the operation of the control rod by the step motor, there are those described in JP-A-55-143604 and JP-A-57-208880.

[0006]

When the control rod drive motor is a step motor and is configured to be capable of fine drive, many drive motor power boards and laying cables are generated. For this reason, adoption of an induction motor (induction motor) as a control rod drive motor is under study.

The induction motor is composed of a stator (stator) on the primary side and a rotor (rotor) on the secondary side, and the secondary winding receives electric energy from the primary side by an electromagnetic induction action to generate air. This is converted into mechanical energy through the gap to rotate the rotor and generate mechanical power.

This induction motor has a principle different from that of a step motor, and unlike the step motor, the rotation speed cannot be controlled by controlling the current on the stator side. Further, the detent torque of the induction motor is almost equal to 0, and even if the current on the stator side is set to 0, the rotor continues to rotate. Therefore, in order to stop the induction motor, a brake that stops from the outside by friction or the like is required.

The stopping torque of the brake has no problem as long as the operation of the electric motor, that is, the operation of the control rod can be instantaneously stopped. However, it is generally difficult to install a large-sized brake because of the restriction on the space under the reactor where the control rod drive device is installed. Therefore, a small brake with excellent performance is required.

An object of the present invention is, when an induction motor is used for electrically driving a control rod, in response to a stop command, the control rod can be stopped, that is, the induction motor can be stopped in the shortest possible time. It is to provide a control rod stop control brake and a brake control system.

[0011]

To achieve the above object, according to one aspect of the present invention, the output is controlled by electrically driving an induction motor to extract / insert a control rod into a reactor. In a control rod stop control system for a nuclear reactor, a brake device for braking a control rod driven by an induction motor and a control device for controlling the operation of the brake device are provided, and the control device stops the operation of the control rod. Therefore, a control rod stop control system for a nuclear reactor is provided, which outputs a brake activation signal for operating a brake device during operation of the control rod.

As the brake device, for example, one having at least two kinds of brakes which are independently operated, that is, a first brake and a second brake is used. Further, the control device, for example, the first brake, the second brake, in this order,
What has a means to control the timing which outputs a brake actuation signal so that it may operate at different timings is used.

The means for controlling the timing of outputting the brake actuation signal may be configured to output a signal for actuating the second brake after a predetermined time has elapsed after the actuation of the first brake.

The present invention may further include a sensor for detecting the rotation speed of the induction motor. In this case, the means for controlling the timing of outputting the brake actuation signal takes in the number of revolutions detected by the sensor for detecting the number of revolutions, and when the number of revolutions becomes smaller than a predetermined reference value, the second A signal for activating the brake may be output.

Furthermore, the present invention can further include a detector for detecting the current position of the control rod. in this case,
The means for controlling the timing of outputting the brake actuation signal, for example, takes in the current position of the control rod detected by the detector, and the deviation between the current position and the set stop target position of the control rod is determined by a predetermined reference value. A signal for activating the first brake may be output when the value becomes smaller than the value.

According to another aspect of the present invention, in addition to the above-described aspect, for example, at least two types of brakes that operate independently, the first and second brakes, and the current position of the control rod are set. The control device further includes a detector for detecting, for example, the first brake, the second brake,
In this order, there is provided a control rod stop control system for a nuclear reactor, in which one having a means for controlling the timing of outputting a brake actuation signal is used so as to operate at different timings. The means for controlling the timing of outputting the brake actuation signal takes in the current position of the control rod detected by the detector, and a deviation between the current position and the set stop target position of the control rod is determined by a first predetermined value. When the deviation is smaller than the reference value, the signal for activating the first brake is output, and when the deviation is smaller than the second reference value, the signal for activating the second brake is output. be able to.

[0017]

[Operation] When the control rod drive motor is an induction motor,
It cannot brake itself. Therefore,
A braking device is used to stop the operation of the control rod. This braking device can also be used for holding after stopping.

Specifically, as a means for stopping the drive of the electric motor in a short time based on the stop signal, it is a miniaturized brake and has a small stopping torque, but two different types of brakes are installed at different positions of the control rod drive mechanism. However, in total, the brake has a large stall torque. As a result, the control rod can be stopped in a short time.

The braking operation timing is as follows:
By operating the two types of brakes with a time delay and operating them in stages, the brakes can be operated in the electric motor rotating state suitable for the stopping torque of the brakes. There is also a method of operating two types of brakes at the same time.

The timing of activating the second brake is delayed by a time period after the first brake is activated to decrease the torque of the electric motor to a specified value, and a method of activating the second brake is detected. There are a method of activating the brake when the rotation speed is reached, a method of activating the brake when the deviation between the current position of the control rod and the target stop position becomes smaller than a predetermined reference value, and the like.

As described above, in the control rod drive device, in order to stop the electric motor for driving the control rod, two kinds of brakes having different stopping torques are installed and operated at appropriate places where the stopping torque acts. As a result, the control rod can be stopped in a shorter time.

Further, by operating the two types of brakes with a time delay and operating them in stages, the brakes can be operated in a motor rotating state suitable for the stopping torque of the brakes. That is, for stopping from the motor rated operation, a brake with a large stall torque is used, and if the second brake is operated at a point where the motor torque decreases and becomes equal to or less than the stall torque of the second brake, , The downtime becomes shorter.

Further, according to the present invention, the control rod of the electric drive control rod drive system can be stopped in a short time from the control rod stop command, and the brake operation timing in consideration of the brake stalling torque is taken. The life can be extended.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a nuclear power plant control rod drive system using an induction motor.

In the reactor 5 to be controlled by this system, a plurality of fuel rods 16 are installed at intervals with being immersed in the cooling water 17. A plurality of control rods 6 are arranged in the space between the fuel rods 16 so that they can be inserted and removed freely.

The control rods 6 are lifted and lowered by the induction motor 7 via the control rod drive mechanism 18, respectively.
The structure is such that it can be inserted into and removed from the space between 6. Further, the control rod position detector 8 for detecting the displacement of the control rod 6 along the longitudinal direction of the control rod drive mechanism 18, that is, the vertical direction of the control rod 6, and the first brake for stopping the induction motor 7. 15A and the second brake 15B are arranged.

The control system used in this embodiment has a device for operating the control rod 6,
Control rod operation monitoring board 1 provided in the main control room, control rod drive auxiliary board 3 having equipment for controlling the operation of the induction motor 7, control rod operation command contents from the main control room, and current control When the operation of the control rod 6 is required by comparing with the state of the rod, a control rod position transmission auxiliary panel 2 for outputting an operation command to the control rod drive auxiliary panel 3 and a control rod having a device for controlling the brake operation It has a brake control device auxiliary board 4.

The control rod drive mechanism 18 is used for the reactor pressure vessel 5
It is attached to the bottom. As shown in FIG. 4 (A), the control rod 6 is pulled out and inserted by the vertical movement of the hollow piston 19 latched by the ball nut 23. The operation of the ball nut 23 is performed by the rotation of the ball screw 20. The rotation of the ball screw 20 is transmitted by the rotation of the electric motor 7. The rotation of the electric motor 7 is
It is monitored by the synchro transmitter 22. The brakes 15A and 15B for stopping the operation are attached to the rotating shaft 21 and the motor rotating portion.

The brakes 15A and 15B are respectively shown in FIG.
As shown in (B) and (C), a disk 151 provided on the rotary shaft 21 side, a solenoid 152 driven by DC (direct current), and a disk attached to the solenoid 152 and electromagnetically attracted. Friction plate 15 in close contact with 151
3 is a disc brake. In this embodiment, the disc 151 and the friction plate 153 are provided in a plurality of layers to enhance the braking force. Although not shown in detail, the friction plate 153 is made of, for example, a material effective for guiding the magnetic flux of the solenoid to the disc 151, for example, a metal plate having a high magnetic permeability and a disc-opposing surface of the metal plate. And a friction member attached to.

The control rod operation / monitoring panel 1 has input / output devices (not shown) for the operator to operate and monitor, and the procedure for pulling and inserting the control rods at the nuclear power plant, and the amount of movement. Control rod operating procedure storage unit 11 for storing control rod operating procedure
And a control rod operation circuit 10 for comparing the input command 9 with the control rod operating procedure and transmitting the pulling / inserting command to the control rod position transmission auxiliary panel 2 if there is no problem in the input command. In the input / output device, a display device for displaying the coordinates of the control rod,
There are a coordinate selection button and an instruction input device for operation command buttons such as control rod operation mode, insertion, and withdrawal. The operator commands the operation with these devices. The signal is sent to the control rod operating circuit 10. However, if the wrong control rod is selected and the control rod is pulled out, it may deviate from the thermal margin of the reactor and become a dangerous state. Therefore, the control rod operating procedure storage unit 11 stores the procedure of pulling out and inserting the control rod and the control rod operating procedure in which the operation amount is determined in advance. Therefore, when the control rod is operated, it is constantly monitored whether the selected control rod is the control rod having the coordinates to be operated without error and whether the operation amount exceeds the specified value.

The control rod position transmission auxiliary panel 2 is provided with signals from the control rod position detector 8 and the control rod operation monitoring panel 1 (central control room).
And a position control circuit 12 for outputting a control rod pull-out / insertion command to the control rod drive auxiliary board 3.
The position control circuit 12 compares the signal from the control rod position detector 8 with the signal from the control rod operation monitoring panel 1 (central control room), and if the control rod position has not reached the pull-out / insertion required value. The control rod pull-out / insertion command is output to the control rod drive auxiliary board 3. On the other hand, when the operating control rod matches the value of the command from the central control room, a control rod stop command is sent to the control rod brake control device auxiliary board 4.

The control rod drive auxiliary board 3 includes a power breaker 13B for shutting off the electric power supplied to the induction motor 7 and a control rod operation direction for determining the rotation direction of the induction motor 7 in response to a signal indicating whether the induction motor 7 is pulled out or inserted. In order to control the switching circuit 13A and the control rod operation direction switching circuit 13A to output a signal indicating whether the command is pulling or inserting, to the control rod operation direction switching circuit 13A, and to turn on / off the power breaker 13B in response to the command. And the induction motor control circuit 13 of. In addition, an AC power source that is a drive source of the induction motor 7 is input into the control rod drive auxiliary board 3, and the power breaker 13B and the control rod operation direction switching circuit 1 are input.
It is supplied to the induction motor 7 via 3A. For example, in the case of pulling out, the induction motor control circuit 13 issues a switching command to the control rod operation direction switching circuit 13A to drive the induction motor 7 in the pulling direction, and further outputs a command to turn on the power to the power breaker 13B. To do. As a result, the electrodes are supplied to the induction motor 7, and the induction motor 7 rotates toward the pull-out side of the control rod 6. As a result, the control rod 6 is pulled out.

The control rod brake control device auxiliary board 4 has a brake circuit 14 which controls the driving of the brakes 15A and 15B in response to a stop command from the control rod position transmission auxiliary board 2. Specifically, in the control rod brake control device auxiliary board 4, when a stop instruction is input from the control rod position transmission auxiliary board 2, this instruction is transmitted to the brake circuit 14. The brake circuit 14 supplies the brake power supply AC to the brake 1
The DC power supply for 5A and 15B operation is converted, and ON / OFF control of the power supply circuit is performed. Therefore, when the control rod is operated, the power supply circuit is turned off and the brake is not applied, but the power supply circuit is turned on and the brake is activated together with the control rod stop signal. That is, the brake circuit 14 functions as a means for controlling the operation timing of the brake together with the control rod position transmission auxiliary board 2.

Next, the operation of this embodiment will be described.
First, the mechanism of power generation in a nuclear power plant will be described. When the fuel (uranium) in the reactor pressure vessel 5 undergoes a nuclear reaction, the heat generated at that time is absorbed by the cooling water 17 filled in the reactor, so that the cooling water boils. The boiling cooling water produces steam 17A, which is sent to the turbine. Electric power is generated by rotating the turbine.

With such a structure, the control for causing the nuclear reaction of the fuel is performed by pulling out / inserting the control rod 6.
That is, when the control rod 6 is in the inserted state, the neutrons necessary for the nuclear reaction are absorbed by the control rod, so that the nuclear reaction does not proceed and therefore no steam is generated. On the other hand, when the control rod 6 is pulled out, the nuclear reaction proceeds and the cooling water boils to generate steam.

Next, the operation control of the control rod will be described. First, the operation of pulling out the control rod will be described with reference to FIG.

The control rods are operated by the control rod operation monitoring board 1 in the central control room. The control rod operation monitoring panel 1 accepts an input of a control rod operation command 9 such as designation of a pullout control rod coordinate and a control rod operation mode (continuous, notch, step) by the operator and a withdrawal command. The signal is transmitted to the control rod operating circuit 10. The control rod operating circuit 10 compares the input command with the control rod operating procedure, and if there is no problem with the input command, the pulling command is transmitted to the position control circuit 12 in the control rod position transmission auxiliary panel 2. In the position control circuit 12, the signal from the control rod position detector 8 is compared with the signal from the central control room, and if the control rod position has not reached the withdrawal request value, the control rod withdrawal command is issued. Input to the induction motor control circuit 13 in 3.

The induction motor control circuit 13 checks whether the command is pulling out or inserting, and a signal indicating the pulling out (switching command).
Is output to the control rod operation direction switching circuit 13A, and in response to the command, the power breaker 13B is turned on. As a result, electric power is supplied to the induction motor 7, and the induction motor 7
The control rod 6 is rotated in the pulling direction. As a result, the control rod 6 is pulled out. In addition, the induction motor control circuit 13
When receiving the stop command, the power breaker 13B is turned off.

In the position control circuit 12, the signal from the control rod position detector 8 is compared with the signal from the control rod operation monitoring panel 1 (central control room), and the position of the control rod 6 being pulled out is pulled out. If the required value has not been reached, the control rod withdrawal command is continuously output to the control rod drive auxiliary board 3. On the other hand, when the position of the operating control rod coincides with the value of the command from the central control room, the position control circuit 12 sends a control rod stop signal to the brake control circuit 14 of the control rod brake control device auxiliary board 4. Is entered.

In the brake control circuit 14, when the control rod is pulled out, the circuit that was in the brake power OFF state is brought to the brake power ON state. As a result, the DC for driving the brake
Electric power is transmitted to the brakes 15A and 15B and is energized to the solenoid 152 shown in FIG. As a result, the disk 15
1 is electromagnetically adsorbed and comes into close contact with the friction plate 153. As a result, the control rod 6 is stopped. Brake circuit 1
The detailed configuration of No. 4 will be described later.

The above operation is an operation at the time of pull-out control.
The operation of the insertion control is similar if the withdrawal is changed to the insertion.

FIG. 3 shows the relationship between the control rod operation command from the central control room and the operation of the induction motor 7 and the operation amount of the control rod based on the command. As shown in the figure, the rotation direction of the induction motor 7 changes depending on whether the control rod operation command is pulling out or inserting. Further, in the case of the stop command, the induction motor 7 is in a stopped state. It is also shown that the pull-out amount increases when the pull-out command is issued, becomes constant when the stop command is issued, and decreases when the insert-command is issued.

Next, the stop control of the control rod drive motor will be described in more detail. 2 (A) and 2 (B) show the outline of the configuration of two examples of the control rod drive motor stop circuit 14. In these examples, the case where the braking torques of the first brake 15A and the second brake 15B are different is shown. That is, in these examples,
A first brake 15A having a large stalling torque and a second brake 15B having a small stalling torque are provided, and the second brake is operated to perform braking in accordance with the torque reduction characteristics of the electric motor due to the first brake. Do. Therefore, the torque reduction characteristic of the electric motor due to the first brake 15A is measured in advance, and the operation timing of the second brake 15B having a small stall torque is set.

The control rod drive characteristic during the braking operation will be further described. First, since the control rod drive induction motor drives the control rod, the rated torque is, for example, about 4 kg.
m. Here, when the first brake having a stop torque of about 7 kg · m is actuated together with the control rod stop command, the electric motor speed decreases as shown by the first brake actuation characteristic T1 in FIG. This speed decrease is caused by, for example, a stall torque of 3 kg · m
The second brake is actuated when the speed becomes suitable for the second brake actuation characteristic T2. As a result, the electric motor
As shown by the characteristic T2 at the time of the second brake operation shown in 5, the vehicle is rapidly stopped.

In the first example for realizing such a stop control, as shown in FIG. 2A, the brake circuit 14 converts the brake AC power supply 140 into a DC power supply for operating the brakes 15A and 15B. The power supply circuit 142 and the output of the power supply circuit 144 are turned on and off corresponding to the brakes 15A and 15B.
Switches 143 and 144 for FF and switches 143 and
And a switch control circuit 141 for controlling the opening and closing of 144. The switch control circuit 141 receives the control rod stop signal, generates a brake operation signal, and outputs the brake operation signal to the switch 144 corresponding to the second brake 15B. Delay timer 141 that delays for a fixed time according to the timing
And 2.

In this example, when the control rod is operating, the switch 1
Both 43 and 144 are off, and the output of the power supply circuit 142 is O.
It becomes FF and the brake cannot be applied. On the other hand, when the control rod stop command is output from the position control circuit 12, the power breaker 13B is turned off in the induction motor control circuit 13. Along with this, also in the brake circuit 14,
When receiving the stop command, the circuit 1411 for generating a brake actuation signal generates and outputs the brake actuation signal. The switch 143 is turned on to energize the first brake 15A to operate it. Also, the delay timer 1412 is activated, and after the delay time of the delay timer 1412 elapses,
The switch 144 is turned on to energize the second brake 15B to operate it. Therefore, first, the first brake having a large stall torque is activated to reduce the rotational torque of the induction motor 7. Then, at a time when the torque of the electric motor 7 due to the first brake is reduced, that is, at a preset timing, the second brake having a small stop torque is operated to stop the drive of the control rod. In this way, in this example, the two types of brakes are operated in stages,
It is possible to efficiently stop the motor.

In the second example, as shown in FIG.
The brake circuit 14 includes a power supply circuit 142 that converts the AC power supply 140 for braking into a DC power supply for operating the brakes 15A and 15B, and the output of the power supply circuit 144.
Switches 143,1 for turning on and off corresponding to A and 15B
44, and a switch control circuit 145 that controls opening and closing of the switches 143 and 144. Switch control circuit 14
Reference numeral 5 denotes a circuit 1451 for receiving a control rod stop signal and generating a brake actuation signal, and a rotational speed R of the induction motor 7 is taken in, and the rotational speed R is a preset rotational speed Drp set in advance.
A rotation speed determination circuit 1452 that detects that the value is m or less and outputs a signal to that effect, and a switch 143 when a motor operation signal and a brake operation signal indicating that the induction motor 7 is operating are output. An AND gate circuit 1453 that turns on the motor, a motor operation signal indicating that the induction motor 7 is operating, a brake operation signal, and a signal indicating that the rotation speed is equal to or lower than a preset specified rotation speed Drpm are output. An AND gate circuit 1454 that turns on the switch 144 when the switch 144 is turned on.

In this example and the example shown in FIG. 6 which will be described later, a sensor 701 for detecting the rotation speed R of the induction motor 7.
Is provided.

In this example, when the control rod is operating, as in the first example, both the switches 143 and 144 are off, the output of the power supply circuit 142 is off, and the brake cannot be applied. On the other hand, when the control rod stop command is output from the position control circuit 12, the power breaker 13B is turned off in the induction motor control circuit 13. At the same time, the switch 143 is turned on on condition that the brake operation signal and the electric motor operation signal are present. Further, the switch 144 is turned on on condition that the brake actuation signal, the electric motor actuation signal, and the signal indicating that the number of revolutions is the prescribed number of points doctor exist.

In the above braking control, the two types of brakes are operated stepwise. The stepwise operation of the above two types of brakes is also effective in extending the life of the brakes. That is, when the second brake is operated in a state where the electric motor drive torque is larger than the brake stop torque, the second brake is worn out and shortens the life of the brake. The life of the brake can be extended. In the present invention, these two types of brakes may be operated simultaneously.

Further, the brake operates to induce the induction motor 7,
That is, after the control rod is stopped, the first and second brakes 15A and 15B are used to hold the control rod so as not to move. Alternatively, either one of the brakes may be used for holding. When the control rod is held by using the brake, the holding is released when the control rod is operated.

In the above embodiment, the control rod operation monitoring board 1 is used.
, Control rod drive auxiliary board 3, and control rod position transmission auxiliary board 2
Although the example in which the control rod brake control device auxiliary board 4 and the control rod brake control device auxiliary device 4 are configured as independent devices has been shown, these may be configured by a device that is appropriately combined. For example, the control rod operation monitoring panel 1, the control rod position transmission auxiliary panel 2, and the control rod brake control device auxiliary panel 4 can be integrated into one device. In this case, the function of each device can be realized as a function of software by using one computer system. A command is output to the control rod drive auxiliary board 3 from a portion corresponding to the control rod position transmission auxiliary board 2 realized by a computer system.

FIG. 6 shows an example of such a system. The system shown in the figure is a diagram functionally showing a portion for performing stop control. Although omitted here, a function of controlling the drive of the induction motor may be additionally provided. Further, in this example, the parts other than the control system are configured similarly to the example shown in FIG.

In FIG. 6, according to the present embodiment, an automatic output adjusting unit 1000 which receives a target output and a current output and outputs an insertion request or a withdrawal request, and an induction motor drive which receives the insertion request or the withdrawal request. / Control rod operation monitoring unit 1100 for controlling stop and brake operations, and control rod stop position control unit 1400 for controlling brakes. The control rod stop position control unit 1400 includes the first and second control rod stop positions.
Brake Noda functions as a means to control the same timing. That is, the deviation A is obtained by receiving the signal from the control rod position detector 8 and the signal from the control rod operation monitoring unit 1100, and the switch 143 corresponding to the first brake is turned on based on the deviation A, or Furthermore, while determining whether to turn on the switch 144 corresponding to the second brake,
Based on the stop command output from the control rod operation monitoring unit 1100, the switch 143 corresponding to the first brake,
Further, control for sequentially turning on the switch 144 corresponding to the second brake is performed. The function of each unit described above is realized by a computer system. Although not shown, the computer system includes a central processing unit, a memory, an input / output interface and the like.

The automatic output adjusting section 1000 is provided with a deviation detecting section 1001 for obtaining the deviation between the target output and the current output, and a hysteresis limiter 1002 for limiting the output of the deviation. An insertion request or a withdrawal request is output via the hysteresis limiter 1002. That is, this automatic output adjustment unit 1000
When the deviation between the target output and the current output is detected by the deviation detection unit 1001 and the deviation is equal to or larger than the specified value specified by the hysteresis limiter 1002,
A determination unit (not shown) determines whether or not the output control by the control rod is appropriate, and if so, outputs an insertion / pull-out request for operating the control rod. Here, for example, when the hysteresis limiter 1002 is 1% and the reduction output is 50%, when the target output is 60%, there is a deviation of 1% or more, so the control rod is pulled out. Request the operation. On the contrary, when the current output is 60% and the target output is 50%, the operation of inserting the control rod is requested. In each case, the withdrawal / insertion command is released when the output reaches 60%.

The control rod withdrawal / insertion request output from the automatic output adjusting unit 1000 is controlled by the control rod operation monitoring unit 11.
Sent to 00. If there is no request, it is interpreted as a stop request.

The control rod operation monitoring unit 1100 includes a control rod operation sequence unit 1101 that sets a control operation sequence based on a program stored in advance, and a stop command output unit 1102 that receives a stop request and outputs a stop command. Prepare That is, the control rod operation sequence unit 110
In 1, the operation sequence of the control rod is stored. Therefore, if the withdrawal request / insertion request continues to be output, the control rod withdrawal / insertion operation is executed according to this sequence, and if the stop request is issued, the stop control is executed.

In the present embodiment, the operation sequence defines, for example, at which step the control rod is stopped by dividing the control rod from all insertion positions to all extraction positions into 200 steps. . Specifically, it is determined in consideration of the reactivity of the control rod. For example, in the operation sequence, the stop steps are 20, 30, 50, 100,
If it is 200, before the specified number of steps (corresponding to the reference values B and C) for those steps, the control rod is stopped at the position of each step,
The first brake and the second brake are controlled to operate sequentially.

In addition to the above-mentioned operation sequence, the control rod stop request is output from the automatic output adjusting unit 1000 when the current output reaches the target output before the stop step defined by the operation sequence is reached. Stop request, manual stop request, stop request based on plant abnormality, etc.

The control rod stop position control unit 1400 has a deviation detection unit 1401 for obtaining a deviation A between a signal from the control rod position detector 8 and a signal from the control rod operation monitoring unit 1100, and a standard with which the deviation A is predetermined. Determine whether it is less than the value B,
When A <B, the first brake 15A (see FIGS. 1 and 4)
When the deviation A is smaller than a predetermined reference value C, the first brake operation determination unit 1402 that turns on the switch 143 that operates the second brake 1 is determined when A <C.
5B (see FIGS. 1 and 4), a second brake operation determination unit 1403 that turns on a switch 144, and a sensor 7
01, the rotation speed of the induction motor 7 is taken in, the rotation speed is detected to be less than the preset rotation speed Drpm, and the switch 144 for activating the second brake 15B (see FIGS. 1 and 4) is operated. And a second brake actuation determination unit 1404 that is turned on.

Next, referring to the flowchart of FIG.
The operation of this embodiment will be described.

When the system is started and the control is started (step S1001), the automatic output adjusting section 1000 of the system causes the deviation detecting section 1001 to take in the target output and the current output to obtain the deviation. (Step S1
002), if there is no deviation, the process returns to step S1001 and the above processing is repeated until the deviation occurs. on the other hand,
When the deviation is generated, when the deviation is equal to or larger than the specified value specified by the hysteresis limiter 1002,
When the deviation A indicates that the current output is less than the target output, the automatic power adjusting unit 1000 checks whether the reactor state has a problem with the control rod withdrawal (step S100).
3). If there is any problem, the extraction operation is not performed and the process waits until the problem disappears. On the other hand, when there is no problem in pulling out the control rod and when inserting the control rod, an insertion request or a pulling out request is output based on the deviation.

In the control rod operation monitoring unit 1100, the control rod operation sequence unit 1101 pulls out a control rod withdrawal / insertion procedure and an operation amount with respect to an insertion request or a withdrawal request based on a control rod operation procedure in which a predetermined operation amount is determined. / Insert command,
It outputs to the control rod drive auxiliary | assistant board 3 which is not shown in FIG. 6 (step S1004).

Here, the control rod operation sequence section 1401
Determines the deviation A between the stop step of the control rod sequence and the current control rod position step, determines whether this deviation A is smaller than a predetermined reference B, and when A <B, the first
The switch 143 corresponding to the brake 15A is turned on (steps S1006 and S1008).

After that, when the braking process for the first brake 15A is being performed based on the deviation A,
The control rod operation sequence unit 1401 obtains the deviation A between the stop step of the control rod sequence and the current control rod position step, determines whether this deviation A is smaller than a predetermined reference C, and if A <C At this time, the switch 144 corresponding to the second brake 15B is turned on (step S1009,
S1011). Here, as the reference C, a value within a range in which the second brake 15B having a small braking torque can be braked is set in advance.

For example, when the current step position is 100 and the target step position is 150, for example, the first brake is operated with the number of steps 130 (reference value B = 20) and the number of steps 140 ( Reference value C = 1
In 0), the second brake is activated. The number of steps of these reference values B and C is determined in consideration of the characteristics of the induction motor 7 and the brake.

This control cannot be applied when a stop request is input before the stop target step. For example, when the number of stop steps in the operation sequence is 150 and the stop request is entered with the number of steps 110,
With this control, it cannot be stopped. In that case, proceed as follows.

The control rod operation sequence section 1101 checks whether or not a stop request has been issued from the automatic output adjustment section 1000. That is, it is checked whether or not the current output matches the target value (step S1005). Continue withdrawing / inserting the control rod until they match. When the target value and the current output match, the process proceeds to (step S1008), a stop command is issued, and the switch 143 is turned on. In addition, the sensor 70
The rotational speed R of the induction motor from 1 is taken in, and it is determined whether or not the rotational speed R is smaller than a predetermined reference rotational speed D. If R <D, the second brake 15B is dealt with. The switch 144 is turned on (step S1010,
S1011).

In this process, in (step S1004), the process of (step S1005) is first performed. If there is no stop request, (step S1005)
It is adjusted so as to perform the processing of 6).

In addition, when a stop instruction is input from the outside due to a manual instruction, a plant abnormality, or the like, the stop instruction is issued (step S1007) and the switch 143 is turned on (step S1008). In this case, the operation of (step S1008) is executed regardless of the current control state. Then, after that, the processes after (step S1010) are executed.

By the above processing, the switches 143 and 1
44 is sequentially turned on, and the first brake 15A and the second brake 15B are operated in two stages. As a result, the operation of the control rod is stopped (step S1012). After this,
First brake 15A and / or second brake 1
The control rod is held stationary by 5B. When the control rod is held by the brake, the holding by the brake is released when the control rod is operated.

As described above, in the present embodiment, the above-described various functions are realized by the braking processing by software in the computer system. of course,
These processes may be distributed and processed for each function by a plurality of computer systems. Further, the same process may be a redundant system that executes a plurality of computer systems.

[0073]

According to the present invention, when a control rod is driven by using an induction motor in a nuclear power plant, the induction motor, that is, the control rod can be stopped in a short time by a stop command. it can. Further, in the present invention, by operating the two types of brakes for stopping the control rod drive step by step, the brakes are operated with appropriate braking torques, so that the brake wear is minimized and the life of the brakes can be extended. Can be expected to be effective.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a nuclear power plant control rod stop control system of the present invention.

FIG. 2A is a block diagram showing an example of the configuration of a control rod stop brake control circuit used in an embodiment of the present invention, and FIG. 2B is a block diagram showing another example.

FIG. 3 is a time chart showing changes over time in the number of revolutions of the induction motor and the control rod drawing material with respect to the control rod operation command in the embodiment of the present invention.

4A is an explanatory view showing an example of the configuration of a control rod drive mechanism, FIG. 4B is a sectional view showing an example of the structure of a first brake incorporated therein, and FIG. 4C is a view of the structure of a second brake. Sectional drawing which shows an example.

FIG. 5 is a graph showing operating characteristics of the first and second brakes in this embodiment.

FIG. 6 is a block diagram showing the configuration of another system for performing the stopping process of the induction motor in the present invention.

7 is a flowchart showing the operation of the system shown in FIG.

[Explanation of symbols] 1 ... Control rod operation monitoring panel, 2 ... Control rod position transmission auxiliary panel, 3
Control rod drive auxiliary board, 4 control rod brake control device auxiliary board, 5 reactor pressure vessel, 6 control rod, 7 induction motor, 8 control rod position detector, 9 control rod operation command, 10
... control rod operating circuit, 11 ... control rod operating procedure, 12 ... position control circuit, 13 ... induction motor control circuit, 13A ... control rod operating direction switching circuit, 14 ... brake control circuit, 15 ... step motor holding brake, 15A ... first brake for induction motor, 15B ... second brake for induction motor, 16
... Fuel rod, 17 ... Cooling water, 17A ... Steam, 18 ... Control rod drive mechanism, 19 ... Hollow piston, 20 ... Ball screw, 2
1 ... Electric motor, 22 ... Synchro transmitter, 23 ... Ball nut.

Claims (8)

[Claims] Claim: What is claimed is: 1. A control rod stop control system for a nuclear reactor, wherein a control rod is electrically driven by an induction motor to control the output by pulling out / inserting the control rod into the reactor, and a control rod driven by the induction motor is braked. And a control device for controlling the operation of the brake device. The control device outputs a brake operation signal for operating the brake device during the operation of the control rod in order to stop the operation of the control rod. A control rod stop control system for a nuclear reactor, which is characterized in that 2. The braking device according to claim 1, wherein the braking device operates independently of at least two of the first and second brakes.
A control rod shutdown control system for a nuclear reactor having a kind of brake. 3. The control device according to claim 2, further comprising means for controlling the timing of outputting the brake actuation signal so that the first brake and the second brake act in this order at different timings. Control rod stop control system for nuclear reactors. 4. The means for controlling the timing of outputting the brake actuation signal according to claim 3, is for outputting a signal for actuating the second brake after a certain period of time has elapsed after the actuation of the first brake. Control rod stop control system for nuclear reactors. 5. The sensor according to claim 3, further comprising a sensor for detecting the rotation speed of the induction motor, wherein the means for controlling the timing of outputting the brake actuation signal takes in the rotation speed detected by the sensor for detecting the rotation speed. A control rod stop control system for a nuclear reactor, which outputs a signal for activating a second brake when the number of revolutions becomes smaller than a predetermined reference value. 6. The detector according to claim 4, further comprising a detector for detecting the current position of the control rod, wherein the means for controlling the timing of outputting the brake actuation signal is the current position of the control rod detected by the detector. Control of the nuclear reactor, which outputs a signal for activating the first brake when the deviation between the present position and the set stop target position of the control rod becomes smaller than a predetermined reference value. Bar stop control system. 7. The detector according to claim 3, further comprising a detector for detecting the current position of the control rod, wherein the means for controlling the timing of outputting the brake actuation signal takes in the current position of the control rod detected by the detector. , When the deviation between the present position and the set target stop position of the control rod becomes smaller than a predetermined first reference value,
A signal for operating the first brake is output, and when the deviation becomes smaller than a second reference value, a signal for operating the second brake is output. Control rod stop control system. 8. The control rod stop control system for a reactor according to claim 2, 3, 4, 5, 6 or 7, wherein the first brake and the second brake have different stop torques.