A method for removing impurities using the action of a hook in a drive mechanism

Abstract

This invention belongs to the technical field of pressurized water reactor nuclear power plants, specifically relating to a method for removing impurities using the action of a drive mechanism's claws. It includes the following scenarios: Scenario 1: using the lifting and lowering of the transfer claws; Scenario 2: using the engagement and disengagement of the transfer claws; Scenario 3: using the engagement and disengagement of the holding claws. The beneficial effects of this invention are: this method can remove impurities without affecting the operation of the nuclear power plant, utilizing the existing rod control system equipment, requiring no additional equipment or disassembly of the drive mechanism, is simple and easy to implement, and allows for ample time window utilization. This improves the economic efficiency of nuclear power plant operation and has significant economic benefits.

Description

Technical Field

[0001] This invention belongs to the technical field of pressurized water reactor nuclear power plants, and specifically relates to a method for removing impurities using the action of a hook in a drive mechanism. Background Technology

[0002] Most pressurized water reactor nuclear power plants use magnetic lifting drive mechanisms. This type of drive mechanism achieves the lifting, insertion, or holding of control rods by coordinating the orderly movements of different clamping components (claws), thereby controlling the reactor power.

[0003] According to feedback from nuclear power plant operations, some drive mechanisms exhibited a lag in their actuation point after prolonged operation. Analysis revealed that one cause of this problem was the accumulation of iron filings and impurities within the drive mechanism's chamber after long-term load operation, obstructing the movement of the hooks. Since the drive mechanism is located within the high-temperature, high-pressure, sealed reactor pressure vessel, there is no method to remove impurities during reactor operation. The only option is to manually remove the impurities by disassembling the drive mechanism during reactor shutdown. This method has the following drawbacks:

[0004] (1) It needs to be carried out 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 sleeve, it is extremely difficult to remove impurities.

[0006] (3) The drive mechanism needs to be disassembled, which involves a large amount of work and takes a long time, affecting the economic efficiency of nuclear power plant operation;

[0007] (4) Since the drive mechanism is irradiated after operation, its operation requires irradiation protection, which is not conducive to the removal of impurities and poses a radiation hazard to the operators. Summary of the Invention

[0008] The purpose of this invention is to provide a method for removing impurities using the action of a hook in a drive mechanism. During the clamping phase of the control rod, the hook is excited to perform actions such as lifting, lowering, releasing, and engaging under no-load conditions. The impact water flow generated by these actions washes away the impurities, causing them to flow out of the hook chamber. This solves the problem of motion lag caused by impurities in the hook chamber obstructing the drive mechanism.

[0009] The technical solution of the present invention is as follows: A method for removing impurities using the action of a hook in a driving mechanism, comprising the following aspects:

[0010] Scenario 1: Utilizing the lifting and lowering of a transfer hook;

[0011] Scenario 2: Utilizing the engagement and disengagement of the transfer hooks;

[0012] Scenario 3: Utilize the engagement and disengagement of the hooks.

[0013] Case 1 includes the following steps:

[0014] Step 11: When impurity removal is required, first confirm that the control rod is held by the retaining hook, and at this time the transmission hook is in a free-release state;

[0015] Step 12: Repeatedly turn the lifting coil on and off, so that the transmission hook repeatedly produces lifting and falling movements in the no-load state. This movement will generate impact water flow at transmission hook chamber A and transmission hook chamber B, so that impurities at transmission hook chamber A and transmission hook chamber B are discharged with the water flow.

[0016] Step 13: During the process of switching the hoisting coil on and off, interrupt the above-mentioned switching process of the hoisting coil at an opportune time, switch the hoisting coil on and off intermittently, observe its waveform, and judge the change of the transmission hook's action point, or switch the transmission hook coil on while the hoisting coil is off, observe its waveform, and judge the change of the transmission hook's 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 transmission hook action point returns to normal, and then the power plant enters normal operation.

[0018] Step 15: If a moving rod command is issued during the impurity removal process, the impurity removal work is stopped. The hook is driven according to the current hook status and the direction of the moving rod command to complete the moving rod command. If it is necessary to continue the impurity removal work, proceed to step 11; otherwise, exit the impurity removal process and restore the normal power plant operation status.

[0019] Case 2 includes the following steps:

[0020] Step 21: When impurity removal is required, first confirm that the control rod is held by the retaining hook, and at this time the transmission hook is in a free release state;

[0021] Step 22: Repeatedly switch the power on and off of the transmission hook coil so that the transmission hook repeatedly engages and disengages under no-load conditions. This action will generate an impact water flow at chamber B of the transmission hook, causing impurities at chamber B of the transmission hook to be discharged with the water flow.

[0022] Step 23: During the process of switching the power on and off of the transmission hook coil, interrupt the power switching process of the transmission hook coil at an opportune time, intermittently switch the power on and off of the lifting coil, observe its waveform, and judge the change of the transmission hook's action point, or switch the power on the transmission hook coil while the lifting coil is de-energized, observe its waveform, and judge the change of the transmission hook's 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 transmission hook action point returns to normal, and then the power plant enters normal operation.

[0024] Step 25: If a moving rod command is issued during the impurity removal process, the impurity removal work is stopped. The hook is driven according to the current hook status and the direction of the moving rod command to complete the moving rod command. If it is necessary to continue the impurity removal work, proceed to step 21; otherwise, exit the impurity removal process and restore the normal power plant operation status.

[0025] Case 3 includes the following steps:

[0026] Step 31: When impurity removal is required, first confirm that the control rod is held by the retaining hook, and at this time the transmission hook is in a free release state;

[0027] Step 32: After applying a large current to the transfer hook for a certain period of time, switch to a small current to switch the control rod to the state where it is held by the transfer hook.

[0028] Step 33: Repeatedly switch the power on and off on the holding hook coil so that the holding hook repeatedly engages and disengages under no-load conditions. This action will generate an impact water flow in the holding hook chamber, causing impurities in the holding hook chamber to be discharged with the water flow.

[0029] Step 34: During the process of switching the energizing and de-energizing the holding hook coil, interrupt the energizing and de-energizing process of the holding hook coil at an opportune time, and intermittently switch the energizing and de-energizing of the holding hook coil to observe its waveform and determine the change of the holding hook's 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 hook action point returns to normal, and then the power plant enters normal operation.

[0031] Step 36: If a moving rod command is issued during the impurity removal process, the impurity removal work is stopped. The hook is driven according to the current hook status and the direction of the moving rod command to complete the moving rod command. If it is necessary to continue the impurity removal work, proceed to step 31; otherwise, exit the impurity removal process and restore the normal power plant operation status.

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

[0033] The beneficial effects of this invention are as follows: This method enables impurity removal without affecting the operation of the nuclear power plant. It utilizes the existing rod control system equipment of the nuclear power plant for impurity removal, requiring no additional equipment or disassembly of the drive mechanism. It is simple, easy to implement, and has a sufficient time window. This improves the economic efficiency of nuclear power plant operation and yields significant economic benefits. Attached Figure Description

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

[0035] In the diagram: 1 First spring, 2 Lifting magnetic pole, 3 Transmitting hook chamber A, 4 Lifting coil, 5 Transmitting hook coil, 6 Transmitting hook magnetic pole, 7 Transmitting hook assembly, 8 Transmitting hook chamber B, 9 Holding hook coil, 10 Holding hook magnetic pole, 11 Holding hook assembly, 12 Holding hook chamber, 13 Third spring, 14 Fourth spring.

[0036] In the diagram, the lifting magnetic pole and the holding hook magnetic pole are fixed components, while the transfer hook magnetic pole, the transfer hook assembly, and the holding hook assembly are moving components. Transfer hook chamber A, transfer hook chamber B, and the holding hook chamber are the moving spaces for the transfer hook magnetic pole, the transfer hook assembly, and the holding hook assembly, respectively. During reactor operation, the drive mechanism (including the aforementioned chambers) is filled with water. When the mechanism is powered on and off:

[0037] - Raising the magnetic pole will drive the transmission hook magnetic pole (and the transmission hook magnetic pole will drive the transmission hook assembly).

[0038] The up-and-down movement squeezes out or draws water into the transfer hook chamber A.

[0039] - The magnetic poles of the transfer hook will drive the transfer hook assembly to move up and down, thereby squeezing out the water in the transfer hook chamber B or drawing the water into the transfer hook chamber B.

[0040] - The magnetic poles of the retaining hook will cause the retaining hook to engage and disengage, thereby squeezing out the water in the retaining hook chamber or drawing the water into the retaining hook chamber.

[0041] When impurities are present in the drive mechanism, they can hinder the smooth movement of the aforementioned moving parts, which may affect the action of the moving rod in the drive mechanism, preventing the control rod from being raised or inserted normally. Detailed Implementation

[0042] The present invention will be 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 inside the high-temperature and high-pressure reactor pressure vessel and is immersed in the reactor coolant (water medium). It is in a clamped state for most of the time. The method for removing impurities by utilizing the hook action of the drive mechanism provided by this invention can be implemented in this state to carry out impurity removal work.

[0044] During periods when the nuclear power plant's power output is stable and control rod operation is not required, the control rods are held in a fixed position by the drive mechanism's retaining hooks. Impurity removal can then be performed. This impurity removal can be carried out using the existing rod control equipment at the nuclear power plant, which is used to energize or de-energize the hook coils. Impurity removal can be performed using one of three methods, or any combination thereof: lifting and lowering the transfer hooks, engaging and disengaging the transfer hooks, or engaging and disengaging the retaining hooks. The procedures are as follows.

[0045] A method for removing impurities using the action of a hook in a drive mechanism includes the following:

[0046] Scenario 1: Utilizing the lifting and lowering of a transfer hook.

[0047] Step 11: When impurity removal is required, first confirm that the control rod is held by the retaining hook, and at this time the transmission hook is in a free-release state;

[0048] Step 12: Repeatedly switch the power on and off of the lifting coil, causing the transmission hook to repeatedly perform lifting and lowering movements under no-load conditions. This movement will cause the transmission hook chamber to... Figure 1 The transfer hook chambers A and B, as shown, generate impact water flow. This causes impurities in transfer hook chambers A and B to be discharged with the water flow.

[0049] Step 13: During the process of switching the hoisting coil on and off, the above-mentioned switching process of the hoisting coil can be interrupted at any time (there is no specific requirement for the interruption time interval, which can be selected according to the actual situation on site, such as interrupting once every minute after each execution of step 12), and the hoisting coil is intermittently switched on and off. Observe its waveform and judge whether the electromechanical delay time of the transmission hook insertion action point meets the required value, or when the hoisting coil is de-energized, the transmission hook coil is energized and its waveform is observed to judge whether the electromechanical delay time of the transmission hook engagement and disengagement action point 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 transmission hook action point returns to normal, and then the power plant enters normal operation.

[0051] Step 15: If a rod-moving command is issued during the impurity removal process, the impurity removal work is stopped. The hook-driven operation is then performed according to the current hook status and the direction of the rod-moving command to complete the command. The decision to continue the impurity removal work is based on the power plant's operating status. If continued, proceed to Step 11; otherwise, exit the impurity removal process and restore normal power plant operation.

[0052] Scenario 2: Utilizing the engaging and disengaging action of the transfer hooks.

[0053] Step 21: When impurity removal is required, first confirm that the control rod is held by the retaining hook, and at this time the transmission hook is in a free release state;

[0054] Step 22: Repeatedly switch the power on and off of the transmission hook coil, causing the transmission hook to repeatedly engage and disengage under no-load conditions. This action will... Figure 1 An impact water flow is generated at point B in the transfer hook chamber, causing impurities at point B to be discharged with the water flow.

[0055] Step 23: During the process of switching the power on and off of the transmission hook coil, the above power-on and power-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 according to the actual situation on site, such as interrupting once every minute after each execution of step 22), and the lifting coil is intermittently powered on and off. Observe its waveform and determine whether the electromechanical delay time of the transmission hook lifting insertion action point meets the required value, or power the transmission hook coil while the lifting coil is de-energized, observe its waveform, and determine whether the electromechanical delay time of the transmission hook engaging and disengaging 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 transmission hook action point returns to normal, and then the power plant enters normal operation.

[0057] Step 25: If a rod-moving command is issued during the impurity removal process, the impurity removal work is stopped. The hook-driven operation is then performed according to the current hook status and the direction of the rod-moving command to complete the command. The decision on whether to continue the impurity removal work is based on the power plant's operating status. If it is necessary to continue the impurity removal work, proceed to Step 21; otherwise, exit the impurity removal process and restore normal power plant operation.

[0058] Scenario 3: Utilizing the engagement and disengagement of the hooks.

[0059] Step 31: When impurity removal is required, first confirm that the control rod is held by the retaining hook, and at this time the transmission hook is in a free release state;

[0060] Step 32: Apply a large current (e.g., 300ms) to the transfer hook for a certain period of time, then switch to a small current to switch the control rod to the state where it is held by the transfer hook.

[0061] Step 33: Repeatedly switch the power on and off on the holding hook coil, causing the holding hook to repeatedly engage and disengage under no-load conditions. This action will cause the... Figure 1 The design maintains an impact water flow within the hook chamber, allowing impurities in the hook chamber to be discharged with the water flow.

[0062] Step 34: During the process of switching the energizing and de-energizing the holding hook coil, the above-mentioned switching the energizing and de-energizing process of the holding hook coil can be interrupted at any time (there is no specific requirement for the interruption time interval, which can be selected according to the actual situation on site, such as interrupting once every minute after each execution of step 32), and the holding hook coil is intermittently switched on and off, and its waveform is observed to determine whether the electromechanical delay time of the holding hook engagement and disengagement 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 hook action point returns to normal, and then the power plant enters normal operation.

[0064] Step 36: If a rod-moving command is issued during the impurity removal process, the impurity removal work is stopped. The hook-driven operation is then performed according to the current hook status and the direction of the rod-moving command to complete the command. The decision to continue the impurity removal work is based on the power plant's operating status. If the impurity removal work needs to continue, proceed to Step 31; otherwise, exit the impurity removal process and restore normal power plant operation.

[0065] like Figure 1 As shown, the excitation of the lifting coil will compress the spring 1, causing the transmission hook magnetic pole and the transmission hook assembly to move upward, squeezing the water in the transmission hook chamber A, causing the water to flow out of the chamber, and driving the impurities out of this area; disconnecting the power supply to the lifting coil will cause the spring 1 to extend, causing the transmission hook magnetic pole and the transmission hook assembly to move downward, causing the transmission hook chamber A to be refilled with water.

[0066] like Figure 1 As shown, the excitation of the lifting coil will compress the spring 1, causing the transmission hook magnetic pole and the transmission hook assembly to move upward, thus filling the transmission hook chamber B with water; disconnecting the power supply to the lifting coil will cause the spring 1 to extend, causing the transmission hook magnetic pole and the transmission hook assembly to move downward, thus draining the water from the transmission hook chamber B, allowing the water to flow out of the chamber and carrying away the impurities there.

[0067] like Figure 1 As shown, energizing the transmission hook coil will compress the second spring, causing the transmission hook assembly to engage (the transmission hook swings into the drive rod); disconnecting the power supply to the transmission hook coil will cause the second spring to extend, causing the transmission hook assembly to disengage (the transmission hook swings out of the drive rod).

[0068] The engagement and disengagement motion of the transfer hook will cause water to flow in the transfer hook chamber B, thereby discharging impurities.

[0069] like Figure 1As shown, energizing the retaining hook coil will compress the third spring, causing the retaining hook assembly to engage (the retaining hook swings into the drive rod); disconnecting the power supply to the retaining hook coil will extend the third spring, causing the retaining hook assembly to disengage (the retaining hook swings out of the drive rod).

[0070] Maintaining the engagement and disengagement of the hook will cause water to flow in the hook chamber, thereby expelling impurities.

[0071] Example

[0072] In practice, the required excitation current can be generated using the human-machine interface or command input terminal of the rod control equipment. The process is as follows:

[0073] Confirm that there is no need for moving rods in the reactor, and confirm that the control rods are in the holding gripper state. At this time, the transfer gripper is in the free release state.

[0074] If there is a lag in the action of the transmission hook, the full current and zero current are repeatedly generated in the lifting coil using the human-machine interface or command input terminal of the rod control equipment. At this time, the magnetic pole of the transmission hook and the entire transmission hook assembly repeatedly perform lifting and falling actions, generating impact water flow at transmission hook chambers B and C to flush out impurities present therein.

[0075] During the process of switching the hoisting coil on and off, the hoisting coil is interrupted every minute. The hoisting coil is intermittently switched on and off, and its waveform is observed to determine the change in the action point of the transmission hook. Alternatively, the transmission hook coil is switched on while the hoisting coil is off, and its waveform is observed to determine the change in the action point of the transmission hook, until the action of the transmission hook returns to normal.

[0076] If the aforementioned actions fail to restore the transfer hook to normal operation, the lifting coil is de-energized using the human-machine interface or command input terminal of the rod control equipment. Then, the transfer hook coil repeatedly generates full current and zero current. At this time, the transfer hook repeatedly performs the action of engaging and disengaging, generating impact water flow at point B of the transfer hook chamber to flush away impurities present therein.

[0077] During the process of switching the power on and off of the transmission hook coil, the power on and off process of the transmission hook coil is interrupted every minute. When the lifting coil is de-energized, the transmission hook coil is energized 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 lag in the action of the holding hook, the human-machine interface or command input terminal of the rod control device is used to repeatedly generate full current and zero current in the holding hook coil. At this time, the holding hook assembly repeatedly performs the action of attracting and releasing, generating an impact water flow in the holding hook chamber to flush away the impurities present therein.

[0079] During the process of switching the holding hook coil on and off, the switching process of the holding hook coil on and off is interrupted every minute. The holding hook coil is intermittently switched on and off, and its waveform is observed to judge the changes in the action point of the transmission hook until the action of the transmission hook 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 hook action point returns to normal, and then the power plant enters normal operation.

[0081] If a new rod-moving command is issued during the impurity removal process, immediately exit the impurity removal process, restore the normal rod-moving response state, and decide whether to perform impurity removal again based on the specific situation. If impurity removal is still required, proceed to the first step. Otherwise, exit the impurity removal process and restore the normal power plant operation state.

[0082] The present invention can remove impurities in the drive mechanism chamber by the action of the drive mechanism, remove impurities in the drive mechanism chamber by the impact water flow caused by the action of the drive mechanism, remove impurities in the transmission hook chamber A and transmission hook chamber B by the overall lifting and falling action of the transmission hook magnetic pole and transmission hook assembly, remove impurities in the transmission hook chamber B by the impact water flow caused by the attraction and release action of the transmission hook, and remove impurities in the holding hook chamber by the impact water flow caused by the attraction and release action of the holding hook assembly.

Claims

1. A method for removing impurities using the action of a hook in a drive mechanism, characterized in that, Including the following situations: Scenario 1: Utilizing the lifting and lowering of a transfer hook; Repeatedly switching the power on and off of the lifting coil causes the transmission hook to repeatedly perform lifting-falling actions under no-load conditions. This action will generate impact water flow at transmission hook chamber A and transmission hook chamber B, causing impurities at transmission hook chamber A and transmission hook chamber B to be discharged with the water flow. During the process of switching the hoisting coil on and off, the above-mentioned switching process of the hoisting coil can be interrupted at any time. The hoisting coil can be intermittently switched on and off to observe its waveform and judge the change of the transmission hook's action point. Alternatively, the transmission hook coil can be energized when the hoisting coil is de-energized to observe its waveform and judge the change of the transmission hook's action point. Scenario 2: Utilizing the engagement and disengagement of the transfer hooks; Repeatedly switching the power on and off of the transmission hook coil causes the transmission hook to repeatedly engage and disengage under no-load conditions. This action generates a water flow at chamber B of the transmission hook, causing impurities at chamber B to be discharged with the water flow. During the process of switching the power on and off of the transmission hook coil, the power switching process of the transmission hook coil can be interrupted at any time. The power is switched on and off intermittently to the lifting coil. The waveform is observed to determine the change of the transmission hook's action point. Alternatively, the transmission hook coil can be powered on while the lifting coil is de-energized. The waveform is observed to determine the change of the transmission hook's action point. Scenario 3: Utilize the engagement and disengagement of the hook claws; After applying a large current to the transmission hook for a certain period of time, the current is switched to a small current, so that the control rod switches to the state of being held by the transmission hook. Repeatedly switching the power on and off of the holding hook coil causes the holding hook to repeatedly engage and disengage under no-load conditions. This action generates a water flow in the holding hook chamber, allowing impurities in the holding hook chamber to be discharged with the water flow. During the process of switching the energizing and de-energizing the holding hook coil, the energizing and de-energizing process of the holding hook coil can be interrupted at any time, and the energizing and de-energizing of the holding hook coil can be intermittently observed to determine the changes in the holding hook's action point. Case 1, Case 2 and Case 3 use one or any combination of them.

2. The method for removing impurities using the action of a hook in a drive mechanism as described in claim 1, characterized in that: When impurity removal is required, first confirm that the control rod is held by the retaining pawl, at which point the transmission pawl is in a free-release state.

3. The method for removing impurities using the action of a hook in a drive mechanism as described in claim 1, characterized in that: If there is no command to move the rod during the impurity removal process, the impurity removal action continues until the transmission hook action point returns to normal, and then the power plant enters normal operation.

4. The method for removing impurities using the action of a hook in a drive mechanism as described in claim 1, characterized in that: If a rod-moving command is issued during the impurity removal process, the impurity removal work is stopped. The hook-driven operation is performed according to the current hook status and the direction of the rod-moving command to complete the rod-moving command. If it is necessary to continue the impurity removal work, one or any combination of the above situations 1-3 will continue. Otherwise, the impurity removal process will be exited and the normal power plant operation status will be restored.

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