Method for removing impurities by utilizing claw action of driving mechanism

Abstract

The invention belongs to the technical field of pressurized water reactor nuclear power stations, and particularly relates to a method for removing impurities through claw actions of a driving mechanism. Comprising the following conditions: 1, lifting and falling of a transfer claw are utilized; 2, the operation is carried out by utilizing the suction and the loosening of the transmission claw; and 3, the operation is carried out by utilizing the suction and the loosening of the holding hook claws. The method has the advantages that impurity removal work can be carried out under the condition that operation of the nuclear power station is not affected, impurity removal is carried out through existing rod control system equipment of the nuclear power station, extra equipment is not needed, disassembling of a driving mechanism is not needed, the method is simple and easy to implement, and available time windows are sufficient. And the operation economy of the nuclear power station is improved, and remarkable economic benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of pressurized water reactor nuclear power plants, and in particular relates to a method for removing impurities by utilizing the claw action of a driving mechanism. Background Art

[0002] Most pressurized water reactor nuclear power plants use a magnetic lifting drive mechanism, which achieves the lifting, insertion or retention of control rods by coordinating the orderly actions of different clamping components (hooks), thereby achieving reactor power control.

[0003] According to the feedback from the operation of the nuclear power plant, some drive mechanisms have the problem of delayed action points after long-term operation. After inspection and analysis, one of the reasons for this problem is that after long-term load operation, iron filings and impurities are generated in the chamber of the drive mechanism, which hinder the action of the hook. Since the drive mechanism is in a closed reactor pressure vessel with high temperature and high pressure, there is no way to remove impurities during the operation of the reactor. The drive mechanism can only be disassembled during the shutdown period of the reactor to manually remove impurities. This method has the following defects:

[0004] (1) It needs to be done offline, which affects the economic efficiency of nuclear power plant operation;

[0005] (2) Due to the complex structure of the drive mechanism chamber, which is located in a narrow and long sleeve, it is extremely difficult to remove impurities;

[0006] (3) The drive mechanism needs to be disassembled, which is labor-intensive and time-consuming, affecting the economic efficiency of nuclear power plant operation;

[0007] (4) Since the driving mechanism is exposed to radiation after operation, its operation requires radiation protection, which is not conducive to the removal of impurities and poses a radiation hazard to the operator. Summary of the invention

[0008] The purpose of the present invention is to provide a method for removing impurities by utilizing the action of the hook of a driving mechanism, utilizing the clamping stage of the control rod to stimulate the hook to perform actions such as no-load lifting, dropping, loosening, and suction, and utilizing the impact water flow generated by its action to flush the impurities and make them flow out of the hook chamber, thereby solving the problem of action hysteresis caused by the impurities in the hook chamber of the driving mechanism.

[0009] The technical solution of the present invention is as follows: A method for removing impurities by using the claw action of a driving mechanism, which includes the following situations:

[0010] Case 1: Using the lifting and lowering of the transfer hook;

[0011] Case 2: Using the engagement and release of the transfer hook;

[0012] Case 3: Utilize the engagement and release of the retaining hook.

[0013] The scenario 1 includes the following steps:

[0014] Step 11: When impurities need to be removed, first confirm that the control rod is in a state of being clamped by the holding hook, and the transfer hook is in a free release state;

[0015] Step 12: repeatedly turning on and off the lifting coil, so that the transfer hook repeatedly produces a lifting-falling action in a no-load state, which will generate impact water flow at the transfer hook chamber A and the transfer hook chamber B, so that the impurities at the transfer hook chamber A and the transfer hook chamber B are discharged with the water flow;

[0016] Step 13: When the lifting coil is powered on and off, the power on and off process of the lifting coil is interrupted at an appropriate time, and the lifting coil is powered on and off intermittently to observe its waveform and determine the change of the transfer hook action point; or the transfer hook coil is powered on when the lifting coil is powered off to observe its waveform and determine the change of the transfer hook action point;

[0017] Step 14: If there is no command to move the rod during the impurity removal process, the impurity removal action can continue until the transfer hook action point returns to normal, and then enters the normal power plant operation state;

[0018] Step 15: If a moving rod command appears during the impurity removal process, the impurity removal work is terminated, the hook is driven according to the current claw state and the moving rod command direction, and the moving rod command is completed. If the impurity removal work needs to be continued, go to step 11, otherwise exit the impurity removal process and restore the normal power plant operation state.

[0019] The described situation 2 comprises the following steps:

[0020] Step 21: When impurity removal is required, first confirm that the control rod is in a state of being clamped by the holding hook, and the transfer hook is in a free release state;

[0021] Step 22: repeatedly turning on and off the transmission hook coil, so that the transmission hook repeatedly produces an attraction-release action in a no-load state, which will generate an impact water flow at the transmission hook chamber B, so that the impurities at the transmission hook chamber B are discharged with the water flow;

[0022] Step 23: When the transmission hook coil is powered on and off, the transmission hook coil is interrupted at an appropriate time, and the lifting coil is powered on and off intermittently to observe its waveform and determine the change of the transmission hook action point; or the transmission hook coil is powered on when the lifting coil is powered off to observe its waveform and determine the change of the transmission hook action point;

[0023] Step 24: If there is no command to move the rod during the impurity removal process, the impurity removal action can continue until the transfer hook action point returns to normal, and then enters the normal power plant operation state;

[0024] Step 25: If a moving rod command appears during the impurity removal process, the impurity removal work is terminated, the hook is driven according to the current claw state and the moving rod command direction, and the moving rod command is completed. If the impurity removal work needs to be continued, go to step 21, otherwise exit the impurity removal process and restore the normal power plant operation state.

[0025] The described situation 3 comprises the following steps:

[0026] Step 31: When impurity removal is required, first confirm that the control rod is in a state of being clamped by the holding hook, and the transfer hook is in a free release state;

[0027] Step 32: A high current is passed through the transfer hook for a certain period of time and then switched to a low current, so that the control rod is switched to a state of being clamped by the transfer hook;

[0028] Step 33: repeatedly turning on and off the power of the holding hook coil, so that the holding hook repeatedly produces an attraction-release action in a no-load state, which will cause an impact water flow to be generated in the holding hook chamber, so that the impurities in the transfer hook chamber are discharged with the water flow;

[0029] Step 34: During the process of turning the holding hook coil on and off, the process of turning the holding hook coil on and off is interrupted at an appropriate time, and the holding hook coil is turned on and off intermittently to observe its waveform and determine the change of the holding hook action point;

[0030] Step 35: If there is no command to move the rod during the impurity removal process, the impurity removal action continues until the claw action point returns to normal, and then the power plant enters a normal operation state;

[0031] Step 36: If a moving rod command appears during the impurity removal process, the impurity removal work is terminated, the hook is driven according to the current claw state and the moving rod command direction, and the moving rod command is completed. If the impurity removal work needs to be continued, go to step 31, otherwise exit the impurity removal process and restore the normal power plant operation state.

[0032] Case 1, Case 2 and Case 3 described above use one or any combination of them.

[0033] The beneficial effects of the present invention are: the method can be used to remove impurities without affecting the operation of the nuclear power plant, and the existing rod control system equipment of the nuclear power plant is used to remove impurities, and no additional equipment is required, and the drive mechanism does not need to be disassembled. It is simple and easy to operate, and the available time window is sufficient. The economic efficiency of the operation of the nuclear power plant is improved, and it has significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a cross-sectional view of the drive mechanism.

[0035] In the figure: 1 the first spring, 2 the lifting magnetic pole, 3 the transfer hook chamber A, 4 the lifting coil, 5 the transfer hook coil, 6 the transfer hook magnetic pole, 7 the transfer hook assembly, 8 the transfer hook chamber B, 9 the holding hook coil, 10 the holding hook magnetic pole, 11 the holding hook assembly, 12 the holding hook chamber, 13 the third spring, 14 the fourth spring.

[0036] In the figure, the lifting pole and the holding claw pole are fixed parts, and the transfer claw pole, the transfer claw assembly, and the holding claw assembly are movable parts. The transfer claw chamber A, the transfer claw chamber B, and the holding claw chamber are the movable spaces of the transfer claw pole, the transfer claw assembly, and the holding claw assembly, respectively. During the operation of the reactor, the driving mechanism (including the aforementioned chambers) is filled with water. When the mechanism is powered on and off:

[0037] -The lifting pole will drive the transfer hook pole (and the transfer hook pole will drive the transfer hook assembly)

[0038] Move up and down, thereby squeezing out the water in the transfer hook chamber A or sucking the water into the transfer hook chamber A;

[0039] -The transfer hook magnetic pole drives the transfer hook assembly to move up and down, thereby squeezing out the moisture in the transfer hook chamber B or sucking the moisture into the transfer hook chamber B;

[0040] -The magnetic pole of the holding hook will drive the holding hook to produce a suction and loosening movement, thereby squeezing out the moisture in the holding hook chamber or sucking the moisture into the holding hook chamber.

[0041] When there are foreign matter in the driving mechanism, the smoothness of the movement of the aforementioned moving parts will be hindered, which may affect the movement of the moving rod of the driving mechanism and make it impossible for the control rod to be lifted or inserted normally. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] During the operation of a nuclear power plant, the drive mechanism is located in a high-temperature and high-pressure reactor pressure vessel and in the reactor coolant (water medium). It is in a clamping state most of the time. The method of removing impurities by utilizing the claw action of the drive mechanism provided by the present invention can be implemented in this state to perform impurity removal work.

[0044] During the period when the power of the nuclear power plant is stable and there is no need for the control rod to move, the control rod is clamped by the driving mechanism and held in a fixed position. At this time, impurity removal can be carried out. The impurity removal work can be carried out using the existing rod control equipment of the nuclear power plant, and the rod control equipment is used to excite or cut off the power of the hook coil. Impurity removal can be carried out by lifting and falling the transfer hook, sucking and releasing the transfer hook, and sucking and releasing the holding hook in one of the three ways or any combination thereof. The processes are as follows.

[0045] A method for removing impurities by using the claw action of a driving mechanism, comprising the following:

[0046] Case 1: Using the lifting and lowering of the transfer hook

[0047] Step 11: When impurities need to be removed, first confirm that the control rod is in a state of being clamped by the holding hook, and the transfer hook is in a free release state;

[0048] Step 12: Repeatedly turn on and off the lifting coil, so that the transfer hook repeatedly produces a lifting-falling action in the no-load state, which will cause the transfer hook chamber to Figure 1 The transfer hook chamber A and the transfer hook chamber B shown generate impact water flow, so that the impurities in the transfer hook chamber A and the transfer hook chamber B are discharged with the water flow.

[0049] Step 13: During the process of turning the lifting coil on and off, the above-mentioned process of turning the lifting coil on and off can be interrupted at any time (there is no specific requirement for the interruption time interval, which can be selected in combination with the actual situation on site, such as interrupting once every one minute of executing step 12), turning the lifting coil on and off intermittently, observing its waveform, and judging whether the electromechanical delay time of the lifting and inserting action point of the transfer hook meets the required value, or turning on the transfer hook coil when the lifting coil is off, observing its waveform, and judging whether the electromechanical delay time of the closing and releasing action point of the transfer hook meets the required value;

[0050] Step 14: If there is no command to move the rod during the impurity removal process, the impurity removal action can continue until the transfer hook action point returns to normal, and then enters the normal power plant operation state;

[0051] Step 15: If a rod moving command appears during the impurity removal process, the impurity removal work is terminated, and the hook driving work is performed according to the current hook state and the rod moving command direction to complete the rod moving command. And it is decided whether to perform the impurity removal work according to the power plant operation status. If it is necessary to continue the impurity removal work, go to step 11, otherwise exit the impurity removal process and restore the normal power plant operation status.

[0052] Case 2: Using the engagement and release of the transfer hook

[0053] Step 21: When impurity removal is required, first confirm that the control rod is in a state of being clamped by the holding hook, and the transfer hook is in a free release state;

[0054] Step 22: Repeatedly turn on and off the transfer hook coil, so that the transfer hook repeatedly produces a pull-on and release action in the no-load state. This action will cause Figure 1 The transfer hook chamber B shown generates an impact water flow, so that the impurities in the transfer hook chamber B are discharged with the water flow.

[0055] Step 23: During the process of turning the transmission hook coil on and off, the above-mentioned turning on and off process of the transmission hook coil can be interrupted at any time (there is no specific requirement for the interruption time interval, which can be selected in combination with the actual situation on site, such as interrupting once every one minute of executing step 22), and the lifting coil is intermittently turned on and off to observe its waveform to determine whether the electromechanical delay time of the lifting and insertion action point of the transmission hook meets the required value, or the transmission hook coil is energized when the lifting coil is de-energized to observe its waveform to determine whether the electromechanical delay time of the transfer hook's attraction and release action point meets the required value;

[0056] Step 24: If there is no command to move the rod during the impurity removal process, the impurity removal action can continue until the transfer hook action point returns to normal, and then enters the normal power plant operation state.

[0057] Step 25: If a rod moving command appears during the impurity removal process, the impurity removal work is terminated, and the hook driving work is performed according to the current hook state and the rod moving command direction to complete the rod moving command. And it is decided whether to perform the impurity removal work according to the power plant operation status. If it is necessary to continue the impurity removal work, go to step 21, otherwise exit the impurity removal process and restore the normal power plant operation status.

[0058] Case 3: Using the suction and release of the holding hook

[0059] Step 31: When impurity removal is required, first confirm that the control rod is in a state of being clamped by the holding hook, and the transfer hook is in a free release state;

[0060] Step 32: A large current is passed through the transfer hook for a certain period of time (e.g., 300 ms) and then switched to a small current, so that the control rod is switched to a state of being clamped by the transfer hook;

[0061] Step 33: Repeatedly turn on and off the power of the holding hook coil, so that the holding hook repeatedly produces a pull-on and release action in the no-load state. This action will cause Figure 1 The shown retaining hook chamber generates an impact water flow, so that the impurities in the transfer hook chamber are discharged along with the water flow.

[0062] Step 34: During the process of powering on and off the holding hook coil, the powering on and off process of the transfer hook coil can be interrupted at any time (there is no specific requirement for the interruption time interval, which can be selected in combination with the actual situation on site, such as interrupting once every one minute of executing step 32), and the holding hook coil is intermittently powered on and off, and its waveform is observed to determine whether the electromechanical delay time of the holding hook closing and releasing action point meets the required value;

[0063] Step 35: If there is no command to move the rod during the impurity removal process, the impurity removal action can continue until the claw action point returns to normal, and then enters the normal power plant operation state.

[0064] Step 36: If a rod moving command appears during the impurity removal process, the impurity removal work is terminated, and the hook driving work is performed according to the current hook state and the rod moving command direction to complete the rod moving command. And it is decided whether to perform the impurity removal work according to the power plant operation status. If it is necessary to continue the impurity removal work, go to step 31, otherwise exit the impurity removal process and restore the normal power plant operation status.

[0065] like Figure 1 As shown, energizing the lifting coil will compress the spring 1, driving the transfer hook magnetic pole and the transfer hook assembly to move upward as a whole, squeezing the moisture in the transfer hook chamber A, causing the moisture to flow out of the chamber, and driving the impurities here to be discharged; disconnecting the power supply of the lifting coil will cause the spring 1 to stretch, driving the transfer hook magnetic pole and the transfer hook assembly to move downward as a whole, so that the transfer hook chamber A will be refilled with water.

[0066] like Figure 1 As shown, energizing the lifting coil will compress the spring 1, driving the transfer hook magnetic pole and the transfer hook assembly to move upward as a whole, filling the transfer hook chamber B with water; disconnecting the power supply to the lifting coil will cause the spring 1 to stretch, driving the transfer hook magnetic pole and the transfer hook assembly to move downward as a whole, discharging the water from the transfer hook chamber B, causing the water to flow out of the chamber, driving the impurities here to be discharged.

[0067] like Figure 1 As shown, energizing the transfer hook coil will compress the second spring, driving the transfer hook assembly to move in (the transfer hook swings into the drive rod); disconnecting the power supply to the transfer hook coil will cause the second spring to stretch, driving the transfer hook assembly to move in (the transfer hook swings out of the drive rod).

[0068] The engaging and releasing movement of the transfer hook will drive water flow in the transfer hook chamber B, thereby driving the impurities to be discharged.

[0069] like Figure 1As shown, energizing the holding hook coil will compress the third spring, driving the holding hook assembly to move in (the holding hook swings into the drive rod); disconnecting the power supply to the holding hook coil will cause the third spring to stretch, driving the holding hook assembly to move in (the holding hook swings out of the drive rod).

[0070] The engaging and disengaging movement of the holding hook will drive water flow in the holding hook chamber, thereby driving the impurities to be discharged.

[0071] Example

[0072] In specific implementation, the required excitation current can be generated by using the human-machine interface or command input terminal of the stick control device. The process is as follows:

[0073] Confirm that there is no need to move the reactor rods, and confirm that the control rods are in the state of holding the hooks, and the transfer hooks are in the state of free release;

[0074] If there is a hysteresis problem in the transfer hook action, the full current and zero current are repeatedly generated in the lifting coil by using the human-machine interface or command input terminal of the rod control device. At this time, the transfer hook magnetic pole and the transfer hook assembly as a whole repeatedly perform lifting and falling actions, and impact water flow is generated at the transfer hook chamber B and the transfer hook chamber C to flush out the impurities therein;

[0075] During the process of powering on and off the lifting coil, the powering on and off process of the lifting coil is interrupted every minute, the lifting coil is intermittently powered on and off, its waveform is observed, and the change of the transfer hook action point is determined, or the transfer hook coil is powered on when the lifting coil is powered off, its waveform is observed, and the change of the transfer hook action point is determined, until the transfer hook action returns to normal;

[0076] If the above actions cannot restore the transfer hook to normal, the lifting coil is powered off by the human-machine interface or command input terminal of the rod control device, and then full current and zero current are repeatedly generated in the transfer hook coil. At this time, the transfer hook repeats the pull-in and release actions, and an impact water flow is generated at the transfer hook chamber B to flush out the impurities in it;

[0077] During the process of switching the transmission hook coil on and off, the transmission hook coil on and off process is interrupted every minute, and the transmission hook coil is energized when the lifting coil is off, and its waveform is observed to determine the change of the transmission hook action point until the transmission hook action returns to normal;

[0078] If there is a hysteresis problem in the holding hook action, the full current and zero current are repeatedly generated in the holding hook coil by using the human-machine interface or command input terminal of the stick control device. At this time, the holding hook assembly repeatedly performs the suction and release actions, and an impact water flow is generated in the holding hook chamber to flush out the impurities in it;

[0079] During the process of turning the holding hook coil on and off, the process of turning the holding hook coil on and off is interrupted every minute, and the holding hook coil is turned on and off intermittently to observe its waveform and judge the change of the transfer hook action point until the transfer hook action returns to normal;

[0080] If there is no command to move the rod during the impurity removal process, the impurity removal action can continue until the claw action point returns to normal, and then enters the normal power plant operation state;

[0081] If a new command to move the rod appears during the impurity removal process, the impurity removal process will be exited immediately, the normal moving rod response state will be restored, and whether to perform impurity removal again will be decided according to the specific situation. If impurity removal is still required, the first step will be entered. Otherwise, the impurity removal process will be exited and the normal power plant operation state will be restored.

[0082] By applying the present invention, impurities in the driving mechanism chamber can be removed by utilizing the action of the driving mechanism, impurities in the driving mechanism chamber can be removed by utilizing the impact water flow caused by the action of the driving mechanism, impurities in the transfer hook chamber A and the transfer hook chamber B can be removed by utilizing the overall lifting and falling action of the transfer hook magnetic pole and the transfer hook assembly, impurities in the transfer hook chamber B can be removed by utilizing the impact water flow caused by the suction and loosening action of the transfer hook, and impurities in the retaining hook chamber can be removed by utilizing the impact water flow caused by the suction and loosening action of the retaining hook assembly.

Claims

1. A method for removing impurities by using the claw action of a driving mechanism, characterized in that: This includes the following situations: Case 1: Using the lifting and lowering of the transfer hook; Case 2: Using the engagement and release of the transfer hook; Case 3: Utilize the engagement and release of the retaining hook.

2. A method for removing impurities by using the claw action of a driving mechanism as claimed in claim 1, characterized in that: The scenario 1 includes the following steps: Step 11: When impurity removal is required, first confirm that the control rod is in a state of being clamped by the holding hook, and the transfer hook is in a free release state; Step 12: repeatedly turning on and off the lifting coil, so that the transfer hook repeatedly produces a lifting-falling action in a no-load state, which will generate impact water flow at the transfer hook chamber A and the transfer hook chamber B, so that the impurities at the transfer hook chamber A and the transfer hook chamber B are discharged with the water flow; Step 13: During the process of turning the lifting coil on and off, the above-mentioned turning on and off process of the lifting coil can be interrupted at any time, and the lifting coil can be turned on and off intermittently to observe its waveform and judge the change of the transfer hook action point, or the transfer hook coil can be turned on when the lifting coil is turned off to observe its waveform and judge the change of the transfer hook action point; Step 14: If there is no command to move the rod during the impurity removal process, the impurity removal action continues until the transfer hook action point returns to normal, and then enters the normal power plant operation state; Step 15: If a moving rod command appears during the impurity removal process, the impurity removal work is terminated, the hook is driven according to the current claw state and the moving rod command direction, and the moving rod command is completed. If the impurity removal work needs to be continued, go to step 11, otherwise exit the impurity removal process and restore the normal power plant operation state.

3. A method for removing impurities by using the claw action of a driving mechanism as claimed in claim 1, characterized in that: The described situation 2 comprises the following steps: Step 21: When impurity removal is required, first confirm that the control rod is in a state of being clamped by the holding hook, and the transfer hook is in a free release state; Step 22: repeatedly turning on and off the transmission hook coil, so that the transmission hook repeatedly produces an attraction-release action in a no-load state, which will generate an impact water flow at the transmission hook chamber B, so that the impurities at the transmission hook chamber B are discharged with the water flow; Step 23: During the process of turning the transmission hook coil on and off, the process of turning the transmission hook coil on and off can be interrupted at any time, and the lifting coil can be turned on and off intermittently to observe its waveform and determine the change of the transmission hook action point, or the transmission hook coil can be turned on when the lifting coil is turned off to observe its waveform and determine the change of the transmission hook action point; Step 24: If there is no command to move the rod during the impurity removal process, the impurity removal action continues until the transfer hook action point returns to normal, and then enters the normal power plant operation state; Step 25: If a moving rod command appears during the impurity removal process, the impurity removal work is terminated, the hook is driven according to the current claw state and the moving rod command direction, and the moving rod command is completed. If the impurity removal work needs to be continued, go to step 21, otherwise exit the impurity removal process and restore the normal power plant operation state.

4. A method for removing impurities by using the claw action of a driving mechanism as claimed in claim 1, characterized in that: The described situation 3 comprises the following steps: Step 31: When impurity removal is required, first confirm that the control rod is in a state of being clamped by the retaining hook, and the transfer hook is in a free release state.

5. A method for removing impurities by using the claw action of a driving mechanism as claimed in claim 4, characterized in that: The described situation 3 comprises the following steps: Step 32: A high current is passed through the transfer hook for a certain period of time and then switched to a low current, so that the control rod is switched to a state of being clamped by the transfer hook.

6. A method for removing impurities by using the claw action of a driving mechanism as claimed in claim 5, characterized in that: The described situation 3 comprises the following steps: Step 33: Repeatedly switch the power on and off for the retaining hook coil, so that the retaining hook repeatedly produces an attraction-release action under no-load condition, which will generate an impact water flow in the retaining hook chamber, so that the impurities in the transfer hook chamber are discharged with the water flow.

7. A method for removing impurities by using the claw action of a driving mechanism as claimed in claim 6, characterized in that: The described situation 3 comprises the following steps: Step 34: During the process of turning the hook claw coil on and off, the process of turning the hook claw coil on and off can be interrupted at any time, and the hook claw coil can be turned on and off intermittently to observe its waveform and determine the change of the action point of the hook claw.

8. A method for removing impurities by using the claw action of a driving mechanism as claimed in claim 7, characterized in that: The described situation 3 comprises the following steps: Step 35: If there is no command to move the rod during the impurity removal process, the impurity removal action continues until the claw action point returns to normal, and then enters the normal power plant operation state.

9. A method for removing impurities by using the claw action of a driving mechanism as claimed in claim 8, characterized in that: The described situation 3 comprises the following steps: The described situation 3 comprises the following steps: Step 36: If a moving rod command appears during the impurity removal process, the impurity removal work is terminated, the hook is driven according to the current claw state and the moving rod command direction, and the moving rod command is completed. If the impurity removal work needs to be continued, go to step 31, otherwise exit the impurity removal process and restore the normal power plant operation state.

10. A method for removing impurities by using the claw action of a driving mechanism as claimed in claim 1, characterized in that: Case 1, Case 2 and Case 3 described above use one or any combination of them.

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