Method for driving and controlling a working shaft of a nuclear reactor core probe unwinding device

Abstract

This invention belongs to the field of nuclear power plant reactor maintenance technology, specifically relating to a method for driving and controlling the working shaft of a nuclear reactor core detector winding device. An AC servo drive motor is used to drive the working shaft; a servo drive encoder is used to achieve precise positioning of the working shaft in the initial, loaded, and winding positions; three non-contact position switches are added to the tail end of the working shaft, corresponding to the three positions: initial position, loaded position, and winding position. This invention achieves precise positioning and control of the working shaft of the extraction device, thereby improving the safety and reliability of the equipment and reducing personnel working time and radiation dose.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power plant reactor maintenance technology, specifically relating to a method for driving and controlling the working shaft of a nuclear reactor core detector roll-out device. Background Technology

[0002] The Tianwan Nuclear Power Plant's VVER unit has 54 neutron temperature measurement channels installed in the reactor core. These channels are used to measure neutron flux, coolant temperature at fuel assembly inlets and outlets, coolant temperature under the reactor top cover, and coolant level in the core under accident conditions. Each neutron temperature measurement channel is approximately 13 meters long, with an upper diameter of 24 mm and a lower diameter of 7.5 mm. The lower section operates continuously within the reactor core and is highly radioactive, with an active section exposure dose rate reaching hundreds of Schiff levels. According to the maintenance program, all neutron temperature measurement channels must be replaced every two refueling cycles; therefore, the decommissioned neutron temperature measurement channels need to be removed.

[0003] The waste neutron temperature measurement channel removal device (hereinafter referred to as the removal device) is a special tool for removing the neutron temperature measurement channel. It mainly consists of a housing, winding device, guiding device, gate valve, straightening device, control system, video monitoring system, and lifting device. The winding device mainly includes an electric head, servo motor, working shaft, proximity switch, and electromagnetic clutch. The electric head and servo motor are the power sources, which drive the working shaft to realize a series of operations such as loading, winding, and unwinding. The electromagnetic clutch realizes the conversion between axial and rotary motion of the working shaft.

[0004] The working shaft has three working positions: in the initial position, the working shaft is fully retracted into the extraction device, with the notch at the head of the working shaft facing upwards; in the loading position, the working shaft should be in the middle of the entire device to facilitate the neutron temperature measurement channel rod to pass through from below; in the winding position, the working shaft is pushed to the left to the bottom, causing the neutron temperature measurement channel rod to rotate, thereby removing the neutron temperature measurement channel. Currently, during use, this tool suffers from problems such as reverse rotation of the working shaft, large positioning accuracy deviations, and thread seizing during the working shaft reset process. Due to the high radiation and high reliability requirements of the waste neutron measurement channel extraction work, this tool has not been successfully applied in the field. To solve this problem, the driving and control method of the working shaft has been redesigned. By utilizing a servo motor and a programmable servo drive encoder, and adding a three-position non-contact proximity switch at the tail of the working shaft, the driving, precise positioning, and control of the working shaft can be achieved. Summary of the Invention

[0005] The purpose of this invention is to provide a method for driving and controlling the working shaft of a nuclear reactor core detector roll-out device, so as to achieve precise positioning and control of the working shaft of the take-out device, thereby improving the safety and reliability of the equipment and reducing personnel working time and radiation dose.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for driving and controlling the working shaft of a nuclear reactor core detector winding device is provided. An AC servo drive motor is used to drive the working shaft; a servo drive encoder is used to accurately position the working shaft in the initial position, loading position and winding position; three non-contact position switches are added to the tail end of the working shaft, corresponding to the three positions of the working shaft: initial position, loading position and winding position.

[0008] 1) The servo drive motor is connected to the electric actuator, and the electric actuator is connected to the working shaft;

[0009] 2) Initial state confirmation: This includes the servo drive encoder being in the zero position, the rightmost proximity switch at the tail end of the working shaft being in the triggered state, and the working shaft initial position signal, drawer closing limit signal, power signal, and all limit switch signals being normal and displayed on the human-machine interface; all of the above signals must be normal for electric operation to be possible, otherwise electric operation is not possible; the limit switch status in each step should be logically interlocked with the operating system. If the limit switch status is inconsistent, the logic protection will be triggered, electric operation will be impossible, and an error will be displayed on the operation interface during manual operation;

[0010] 3) Loading stage: The electromagnetic clutch engages, and the servo drive motor drives the working shaft to move forward. When the positioning shaft boss at the tail end of the working shaft reaches the loading position, the loading position proximity switch signal is triggered, or after the servo drive encoder count reaches the set value, the PLC control system controls the servo drive motor to power off and stop working, and the working shaft reaches the loading position. The operator opens the anti-detachment device at the bottom of the winding device and sends the waste neutron measurement channel tube bundle into the U-shaped groove at the front end of the working shaft to complete the loading work. At this time, the loading channel triggers the limit signal of rod insertion. After loading, the straightening device must be returned to the low position to trigger the low position limit signal; otherwise, the PLC control system will prohibit further operation.

[0011] 4) Winding Stage: First, the electromagnetic clutch engages, and the working shaft continues to move forward axially. When the working shaft reaches its left limit, its axial physical travel is set during the design phase, and it can no longer move axially. This triggers the extreme left position proximity switch signal, or the servo drive encoder count reaches the set value. The PLC control system then de-energizes the electromagnetic clutch, and the working shaft rotates to wind the waste neutron measurement channel. Simultaneously, the operator operates the guide ring to control the uniformity of the winding. During this process, the extreme left position proximity switch signal must be maintained at all times to prevent the working shaft from retracting. When the waste neutron measurement channel load limit signal is triggered, the winding continues with a delay to ensure that the entire waste neutron measurement channel is removed. The winding work is then completed, and the completion of the winding work is confirmed through the CCTV monitoring system.

[0012] 5) Detachment stage: First, the guide ring is fully retracted, triggering the limit signal to provide a channel for detachment; then the electromagnetic clutch is engaged, and the servo drive motor drives the working shaft to perform a retraction motion. When the working shaft retracts to the far right position at the tail end, the proximity switch is triggered, the servo drive motor is powered off and stops working, and the rolled-up core detector falls into the cavity. At this time, the position encoder of the servo drive motor is initialized to facilitate the start of the next process.

[0013] 6) Return to initial position stage: The guide ring returns to the middle position, triggering the limit signal, the electromagnetic clutch is de-energized, and the electric actuator handwheel is manually operated to insert the mechanical clutch into the groove of the electromagnetic clutch. At this time, the U-shaped groove at the front end of the working shaft is vertically upward, and other limit signals are normal. The position initialization work is completed at this time.

[0014] The electric actuator is connected to the working shaft via a thread.

[0015] After the limit signal for the waste neutron measurement channel is triggered, the winding continues for 20 seconds to ensure that the waste neutron measurement channel is completely removed.

[0016] Two sets of torque protection are adopted. The first-level torque protection uses the torque protection switch inside the electric head, while the second-level torque protection uses the torque protection of the servo drive motor. The value is set lower than that of the first level. When the torque is exceeded, the second-level protection torque alarm is triggered first, and the servo drive motor stops working. When the second-level torque protection fails, and the value of the first-level torque protection is reached, the first-level torque protection is activated, the servo drive motor stops working, and the power is cut off.

[0017] The beneficial effects achieved by this invention are as follows:

[0018] 1) An AC servo motor is used to drive the working axis, and a servo-driven encoder is used to control the positioning accuracy of the working axis;

[0019] 2) Design a new mechanical structure at the tail end of the working shaft, adding three non-contact limit switches for precise control and display of the three working positions of the working shaft;

[0020] 3) Two sets of torque protection designs are adopted: one for the electric head torque protection switch and the other for the servo motor torque protection.

[0021] 4) Servo-driven encoders and proximity switches are used to control the stopping action of each working position of the working axis, and are also used for position monitoring of the working axis;

[0022] 5) Multiple protection logics to ensure the safety and reliability of the equipment: Two position protection logics are added, that is, the next operation can only be performed when the servo encoder value reaches the set value and the proximity switch is triggered, to prevent the working axis from malfunctioning.

[0023] 6) Intelligent Visual Human-Machine Interaction System: Based on the servo drive encoder signal and proximity switch position signal, the system can dynamically monitor the operating status of each actuator of the device and add fault diagnosis function. Attached Figure Description

[0024] Figure 1 Schematic diagram A shows a method for driving and controlling the working shaft of a nuclear reactor core detector roll-out device.

[0025] Figure 2 Schematic diagram B shows a method for driving and controlling the working shaft of a nuclear reactor core detector roll-out device.

[0026] In the diagram: 1-Working axis; 2-Leftmost proximity switch; 3-Load position proximity switch; 4-Rightmost proximity switch. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0028] 1) An AC servo motor is used to drive the working shaft; a servo drive encoder is used to accurately position the working shaft in the initial position, loading position and winding position. The servo drive encoder can effectively improve the position control accuracy.

[0029] 2) Add three non-contact position switches at the tail end of the working shaft, corresponding to the three positions of the working shaft: initial position, loading position, and winding position; to achieve mechanical control and monitoring of the working shaft position;

[0030] 3) Optimize the operation process, design the electrical control system, add interlocking protection logic for servo encoders and proximity switches to improve the control accuracy and reliability of the system; add a visual human-machine interaction system to realize dynamic monitoring of the operating status of each actuator of the device, add fault diagnosis function, and retain manual operation function.

[0031] 4) Torque protection: Two sets of torque protection are adopted. The first-level torque protection uses the torque protection switch inside the electric head, and the second-level torque protection uses the servo motor. The value is set lower than that of the first level. When the torque is exceeded, the second-level protection torque alarm will be triggered first, and the motor will stop working. When the second-level torque protection fails, the first-level torque protection will be activated when the torque reaches the value of the first-level torque protection, the motor will stop working and the power supply will be cut off.

[0032] 5) Position protection design: The position encoder is set to a working range. If the working range is exceeded, the drive motor will stop for protection.

[0033] 6) Visualized human-computer interaction system: Based on the servo motor position encoder signal and position switch signal, the system simulates the position signal of the working axis, simulates the working process of the working axis and displays it on the display panel. The servo position encoder provides position information.

[0034] 1) The servo drive motor is connected to the electric actuator, and the electric actuator is connected to the working shaft via a thread;

[0035] 2) Initial state confirmation: This includes the servo drive encoder being in the zero position, the rightmost proximity switch at the tail end of the working shaft being in the triggered state, and the working shaft initial position signal, drawer closing limit signal, power signal, and all limit switch signals being normal and displayed on the human-machine interface; all of the above signals must be normal for electric operation to be possible, otherwise electric operation is not possible; the limit switch status in each step should be logically interlocked with the operating system. If the limit switch status is inconsistent, the logic protection will be triggered, electric operation will be impossible, and an error will be displayed on the operation interface during manual operation;

[0036] 3) Loading Stage: The electromagnetic clutch engages, and the servo drive motor drives the working shaft forward. When the positioning boss at the tail end of the working shaft reaches the loading position, it triggers the loading position proximity switch signal, or the servo drive encoder count reaches the set value. The PLC control system then controls the servo drive motor to power off and stop working, and the working shaft reaches the loading position. The operator opens the anti-detachment device at the bottom of the winding device and sends the waste neutron measurement channel tube bundle into the U-shaped groove at the front end of the working shaft to complete the loading work. At this time, the loading channel triggers the limit signal for rod insertion. After loading, the straightening device must be returned to the low position to trigger the low position limit signal; otherwise, the PLC control system will prohibit further operation.

[0037] 4) Winding Stage: First, the electromagnetic clutch engages, and the working shaft continues to move forward axially. When the working shaft reaches its left limit, due to the axial physical travel set in the design, it can no longer move axially. This triggers the extreme left position proximity switch signal, or the servo drive encoder count reaches the set value. The PLC control system then de-energizes the electromagnetic clutch, and the working shaft rotates to wind the waste neutron measurement channel. Simultaneously, the operator operates the guide ring to control the uniformity of the winding. During this process, the extreme left position proximity switch signal must be maintained at all times to prevent the working shaft from retracting. After the waste neutron measurement channel load limit signal is triggered, the winding continues for a 20-second delay to ensure that the waste neutron measurement channel is completely removed. The winding work is then completed, and the completion is confirmed through a television monitoring system.

[0038] 5) Detachment stage: First, the guide ring is fully retracted, triggering the limit signal to provide a channel for detachment; then the electromagnetic clutch is engaged, and the servo drive motor drives the working shaft to perform a retraction motion. When the working shaft retracts to the far right position at the tail end, the proximity switch is triggered, the servo drive motor is powered off and stops working, and the rolled-up core detector falls into the cavity. At this time, the position encoder of the servo drive motor is initialized to facilitate the start of the next process.

[0039] 6) Return to initial position stage: The guide ring returns to the middle position, triggering the limit signal, the electromagnetic clutch is de-energized, and the electric actuator handwheel is manually operated to insert the mechanical clutch into the groove of the electromagnetic clutch. At this time, the U-shaped groove at the front end of the working shaft is vertically upward, and other limit signals are normal. The position initialization work is completed at this time.

Claims

1. A method for driving and controlling the working shaft of a nuclear reactor core detector roll-out device, characterized in that: An AC servo drive motor is used to drive the working shaft; a servo drive encoder is used to accurately position the working shaft in the initial position, loading position, and winding position; three non-contact position switches are added to the tail end of the working shaft, corresponding to the three positions of the working shaft: initial position, loading position, and winding position. 1) The servo drive motor is connected to the electric actuator, and the electric actuator is connected to the working shaft; 2) Initial state confirmation: This includes the servo drive encoder being in the zero position, the rightmost proximity switch at the tail end of the working shaft being in the triggered state, and the working shaft initial position signal, drawer closing limit signal, power signal, and all limit switch signals being normal and displayed on the human-machine interface; all of the above signals must be normal for electric operation to be possible, otherwise electric operation is not possible; the limit switch status in each step should be logically interlocked with the operating system. If the limit switch status is inconsistent, the logic protection will be triggered, electric operation will be impossible, and an error will be displayed on the operation interface during manual operation; 3) Loading stage: The electromagnetic clutch engages, and the servo drive motor drives the working shaft to move forward. When the positioning shaft boss at the tail end of the working shaft reaches the loading position, the loading position proximity switch signal is triggered, or after the servo drive encoder count reaches the set value, the PLC control system controls the servo drive motor to power off and stop working, and the working shaft reaches the loading position. The operator opens the anti-detachment device at the bottom of the winding device and sends the waste neutron measurement channel tube bundle into the U-shaped groove at the front end of the working shaft to complete the loading work. At this time, the loading channel triggers the limit signal of rod insertion. After loading, the straightening device must be returned to the low position to trigger the low position limit signal; otherwise, the PLC control system will prohibit further operation. 4) Winding Stage: First, the electromagnetic clutch engages, and the working shaft continues to move forward axially. When the working shaft reaches its left limit, its axial physical travel is set during the design phase, and it can no longer move axially. This triggers the extreme left position proximity switch signal, or the servo drive encoder count reaches the set value. The PLC control system then de-energizes the electromagnetic clutch, and the working shaft rotates to wind the waste neutron measurement channel. Simultaneously, the operator operates the guide ring to control the uniformity of the winding. During this process, the extreme left position proximity switch signal must be maintained at all times to prevent the working shaft from retracting. When the waste neutron measurement channel load limit signal is triggered, the winding continues with a delay to ensure that the entire waste neutron measurement channel is removed. The winding work is then completed, and the completion of the winding work is confirmed through the CCTV monitoring system. 5) Detachment stage: First, the guide ring is fully retracted, triggering the limit signal to provide a channel for detachment; then the electromagnetic clutch is engaged, and the servo drive motor drives the working shaft to perform a retraction movement. When the working shaft retracts to the far right position at the tail end, the proximity switch is triggered, the servo drive motor is powered off and stops working, and the rolled-up core detector falls into the cavity. At this time, the position encoder of the servo drive motor is initialized to facilitate the start of the next process. 6) Return to initial position stage: The guide ring returns to the middle position, triggering the limit signal, the electromagnetic clutch is de-energized, and the electric actuator handwheel is manually operated to insert the mechanical clutch into the groove of the electromagnetic clutch. At this time, the U-shaped groove at the front end of the working shaft is vertically upward, and other limit signals are normal. The position initialization work is completed at this time.

2. The method for driving and controlling the working shaft of the nuclear reactor core detector roll-out device according to claim 1, characterized in that: The electric actuator is connected to the working shaft via a thread.

3. The method for driving and controlling the working shaft of the nuclear reactor core detector roll-out device according to claim 1, characterized in that: After the limit signal for the waste neutron measurement channel is triggered, the winding continues for 20 seconds to ensure that the waste neutron measurement channel is completely removed.

4. The method for driving and controlling the working shaft of the nuclear reactor core detector roll-out device according to claim 1, characterized in that: Two sets of torque protection are adopted. The first-level torque protection uses the torque protection switch inside the electric head, while the second-level torque protection uses the torque protection of the servo drive motor. The value is set lower than that of the first level. When the torque is exceeded, the second-level protection torque alarm is triggered first, and the servo drive motor stops working. When the second-level torque protection fails, and the value of the first-level torque protection is reached, the first-level torque protection is activated, the servo drive motor stops working, and the power is cut off.

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