Fuel assembly repair system and repair method

Abstract

The application relates to a fuel assembly repairing system and a repairing method. The fuel assembly repairing system comprises a rod extracting tool, a moving platform and a tube seat dismounting tool. The tube seat of the fuel assembly is first disconnected from the fuel rod by the tube seat dismounting tool, so that the fuel rod is exposed; then the moving platform is used to move the rod extracting tool above the fuel rod, so that the rod extracting tool can move the fuel rod to be replaced out and reinsert a new fuel rod into the tube seat of the fuel assembly; and then the tube seat dismounting tool is used to mount the tube seat again, so that the replacement work of the fuel rod is realized. The replacement operation is simpler and more convenient, the repairing process is stable, and the fuel assembly repairing system has high use reliability and use safety.

Description

Technical Field

[0001] This application relates to the field of nuclear power technology, and in particular to a system and method for repairing fuel assemblies. Background Technology

[0002] In existing nuclear power plant fuel assembly repair projects, it is generally necessary to remove the damaged fuel rod from the fuel assembly and fill it with a specific replacement rod in its original position (i.e., the original location of the fuel rod) to ensure that the fuel assembly cell structure is not affected.

[0003] Currently, the replacement rod manufacturing process used in nuclear power plant repair projects is complex, difficult, and costly, and has a long production cycle, which directly affects the normal operation of fuel assembly repair projects within nuclear power plants. Summary of the Invention

[0004] Therefore, it is necessary to provide a fuel assembly repair system to address the problem of the complexity of existing fuel rod replacement processes.

[0005] A repair system for a fuel assembly, the fuel assembly including two tube seats and a plurality of fuel rods connected between the two tube seats; the repair system for the fuel assembly includes:

[0006] A pipe seat assembly / disassembly tool is used to connect or disconnect the pipe seat from the fuel rod.

[0007] A rod-pulling tool is used to clamp the fuel rod and insert or remove the fuel rod from the tube socket;

[0008] A mobile platform is used to install the rod-pulling tool and move the rod-pulling tool above the fuel rod.

[0009] In one embodiment, the mobile platform includes:

[0010] A first moving mechanism is connected to the drawing tool and is used to drive the drawing tool to move along a first direction;

[0011] A second moving mechanism is connected to the first moving mechanism; the second moving mechanism is used to drive the pulling tool to move along a second direction.

[0012] A third moving mechanism is connected to the second moving mechanism; the third moving mechanism is used to drive the drawing tool to move along a third direction; the first direction, the second direction and the third direction are perpendicular to each other.

[0013] In one embodiment, the rod-pulling tool includes two grippers for gripping the fuel rod and a first drive module for driving the grippers to move in a first direction, the first drive module being connected to the first moving mechanism.

[0014] In one embodiment, the rod-pulling tool further includes a positioning module for abutting against the fuel rod and a second driving module for driving the positioning module to move along the first direction, the positioning module being located between the two grippers.

[0015] In one embodiment, the fuel assembly repair system further includes a connector adapter for connection to the connector.

[0016] In one embodiment, the fuel assembly repair system further includes an adapter removal tool for locking the connector adapter to the connector or loosening the connector adapter from the connector.

[0017] In one embodiment, the fuel assembly repair system further includes an adapter hoisting tool for hoisting the connector adapter to the target location.

[0018] In one embodiment, the fuel assembly repair system further includes a height measuring tool for measuring the height of the pipe seat.

[0019] In one embodiment, the fuel assembly repair system further includes a video surveillance mechanism for monitoring the fuel assembly.

[0020] In one embodiment, the fuel assembly repair system further includes an auxiliary hook mechanism for moving the pull rod tool to the mobile platform.

[0021] In one embodiment, the auxiliary hook mechanism includes a sling and a tension gauge mounted on the sling, the sling being used to hoist the pull bar tool to the mobile platform.

[0022] A method for repairing a fuel assembly, based on the fuel assembly repair system described above, the method comprising the following steps:

[0023] The connection between the tube seat and the fuel rod is disconnected using the tube seat disassembly and assembly tool;

[0024] The mobile platform moves the rod-pulling tool above the fuel rod, causing the tool to clamp the fuel rod to be replaced and remove it from the tube seat.

[0025] A new fuel rod is inserted into the tube socket using a rod-pulling tool;

[0026] The fuel assembly socket is reinstalled using a socket removal and installation tool.

[0027] In one embodiment, before the step of disconnecting the tube socket from the fuel rod, the method further includes: hoisting the tube socket adapter to the fuel assembly and securing the tube socket of the fuel assembly and the tube socket adapter;

[0028] The step of reinstalling the connector of the fuel assembly includes: hoisting the connector adapter and the connector onto the fuel assembly; connecting the connector to the fuel assembly; and disconnecting the connector from the connector adapter.

[0029] In one embodiment, the step of refilling the fuel assembly into the socket further includes:

[0030] Install fuel rod inspection device;

[0031] Lower the fuel rods and collect eddy current signals;

[0032] Video inspection.

[0033] The aforementioned fuel assembly repair system includes a rod extraction tool, a moving platform, and a socket removal and installation tool. The socket removal and installation tool first disconnects the fuel assembly socket from the fuel rod, exposing the fuel rod. Then, the moving platform moves the rod extraction tool above the fuel rod, allowing it to remove the fuel rod to be replaced and insert a new fuel rod into the socket. Finally, the socket removal and installation tool reinstalls the socket, thus replacing the fuel rod. The replacement operation is simpler and more convenient, the repair process is appropriate and stable, and it has high reliability and safety in use. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a fuel assembly repair system provided in an embodiment of this application.

[0035] Figure 2 for Figure 1 The diagram shows the first state of the extraction tool in the repair system.

[0036] Figure 3 for Figure 2 The diagram shows the second state of the extraction tool in the repair system.

[0037] Figure 4 for Figure 3 The diagram shows the third state of the extraction tool in the repair system.

[0038] Figure 5for Figure 4 The diagram shows the extraction tool in the fourth state of the repair system.

[0039] Figure 6 This is a schematic diagram of a fuel assembly provided in one embodiment of this application.

[0040] Figure 7 This is a schematic diagram of a tube fixing tool in a repair system provided in an embodiment of this application.

[0041] Figure 8 This is a schematic diagram of a screw removal and installation tool in a repair system provided in an embodiment of this application.

[0042] Figure 9 for Figure 1 A schematic diagram of the mobile platform in the repair system is shown.

[0043] Figure 10 This is a schematic diagram of an auxiliary hook mechanism in a repair system provided in an embodiment of this application.

[0044] Figure 11 This is a schematic diagram of the upper tube socket and tube socket adapter in a repair system provided according to an embodiment of this application.

[0045] Figure 12 This is a schematic diagram of an adapter hoisting tool in a repair system provided in an embodiment of this application.

[0046] Figure 13 This is a schematic diagram of a guide cylinder in a repair system provided in an embodiment of this application.

[0047] Figure 14 This is a partial schematic diagram of a height measuring tool in a repair system provided in an embodiment of this application.

[0048] Figure 15 A flowchart illustrating a method for repairing a fuel assembly according to an embodiment of this application.

[0049] Reference numerals: 10. Fuel assembly repair system; 100. Moving platform; 110. First moving mechanism; 111. First lead screw; 112. First guide rail; 120. Second moving mechanism; 121. Second guide rail; 130. Third moving mechanism; 131. Third guide rail; 140. Connecting seat; 150. Fixing plate; 200. Pulling tool; 210. Gripper; 211. Grip head; 220. Positioning module; 230. First drive module; 240. Second drive module; 300. Pipe socket removal and installation tool; 310. Pipe socket fixing tool; 311. Pin; 312. Brake; 313. Handle; 314. Support rod; 315. Support frame; 320. Screw removal and installation tool 321. Rotary handle; 322. Cylinder; 323. Disassembly / assembly rod; 324. Grab; 325. Clamping lock; 1000. Fuel assembly; 410. Auxiliary hook mechanism; 411. Sling; 412. Hook; 413. Force gauge; 420. Pipe seat adapter; 421. Positioning pin; 4211. Expansion plate; 430. Adapter lifting tool; 431. Lifting part; 4311. Connecting hole; 432. Lifting drive component; 440. Guide tube; 450. Height measuring tool; 451. Ruler; 1000. Fuel assembly; 1010. Fuel rod; 1011. Snap-fit ​​part; 1020. Upper pipe seat; 1021. Pin hole; 1022. Snap-fit ​​groove; 1030. Lower pipe seat. Detailed Implementation

[0050] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0051] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0052] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0053] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0054] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0055] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0056] Figure 1 A schematic diagram of a fuel assembly repair system 10 according to an embodiment of this application is shown. (See attached diagram.) Figure 1 , Figure 3 , Figures 6 to 8As shown, one embodiment of this application provides a fuel assembly repair system 10, wherein the fuel assembly 1000 includes two tube seats and a plurality of fuel rods 1010 connected between the two tube seats. Taking the underwater placement of the fuel rods 1010 as an example, the tube seat located at the upper end of the fuel rods 1010 is the upper tube seat 1020, and the tube seat located at the lower end of the fuel rods 1010 is the lower tube seat 1030. The fuel assembly repair system 10 includes a tube seat disassembly and assembly tool 300, a rod removal tool 200, and a moving platform 100. The tube seat disassembly and assembly tool 300 is used to connect or disconnect the tube seat from the fuel rods 1010. The rod removal tool 200 is used to clamp the fuel rods 1010 and insert or remove the fuel rods 1010 from the lower tube seat 1030. The moving platform 100 is used to install the rod removal tool 200 and move the rod removal tool 200 above the fuel rods 1010.

[0057] When it is necessary to replace the fuel rod 1010 in the fuel assembly 1000, taking the removal of the upper pipe seat 1020 as an example, firstly, the upper pipe seat 1020 of the fuel assembly 1000 is disconnected from the fuel rod 1010 using the pipe seat removal and installation tool 300, exposing the fuel rod 1010; then, the rod extraction tool 200 is moved above the fuel rod 1010 using the moving platform 100, more specifically, above the fuel rod 1010 to be replaced, so that the rod extraction tool 200 can remove the fuel rod 1010 to be replaced from the lower pipe seat 1030, and the new fuel rod 1010 is reinserted into the lower pipe seat 1030; then, the upper pipe seat 1020 is reinstalled onto the fuel rod 1010 using the pipe seat removal and installation tool 300, thereby completing the replacement of the fuel rod 1010. The replacement operation is simpler and more convenient, the repair process is appropriate and stable, and it has high reliability and safety in use.

[0058] The two tube seats not only increase the positional stability of the fuel rods 1010, preventing them from shifting vertically, but also prevent external impurities from entering the fuel rods 1010, thus protecting the fuel assembly. The two tube seats are an upper and a lower tube seat, with a frame between them containing over two hundred fuel rods 1010, vertically inserted. The frame further limits and secures the fuel rods 1010, and the frame and tube seats are threaded together. Multiple screws between the tube seats and the fuel assembly frame can be removed using a tube seat removal tool. When replacing fuel rods, the new fuel rod 1010 is simply inserted into the fuel hole in the frame. Furthermore, in addition to the fuel holes for accommodating the fuel rods 1010, the frame also has multiple reinforcing tubes for connecting to the upper tube seat. These reinforcing tubes extend vertically and are spaced apart from the fuel rods 1010, meaning the fuel rods 1010 are not housed within the reinforcing tubes.

[0059] like Figures 6 to 8 As shown, the pipe seat installation / removal tool 300 includes a pipe seat fixing tool 310 and a screw installation / removal tool 320. The pipe seat fixing tool 310 includes a support rod 314, with a support frame 315 fixed to the bottom of the support rod 314. The support frame 315 is equipped with a brake 312 and at least two prongs 311. A handle 313 is provided on the support rod 314, passing through the support rod 314, and the axis of the handle 313 is perpendicular to the axis of the support rod 314. The screw installation / removal tool 320 includes a hollow installation / removal rod 323. A clamping lock 325 is installed at the top of the installation / removal rod 323, and a gripper 324 is installed at the bottom of the installation / removal rod 323. A rotating handle 321 and a cylinder 322 are fitted onto the outer wall of the installation / removal rod 323, with the rotating handle 321 positioned between the cylinder 322 and the clamping lock 325. The cylinder 322 communicates internally with the installation / removal rod 323.

[0060] Taking the disassembly of the upper tube seat 1020 as an example, the tube seat fixing tool 310 is moved to directly above the upper tube seat 1020 using tools such as a crane. The pins 311 of the tube seat fixing tool 310 are slowly inserted into the corresponding holes of the upper tube seat 1020. The handle 313 of the tube seat fixing tool 310 is pressed down so that the brake 312 is inserted into the upper tube seat 1020 to lock the upper tube seat 1020. Using a crane, move the screw removal tool 320 directly above the upper pipe seat 1020. Insert the gripper 324 of the screw removal tool 320 into any screw hole of the upper pipe seat 1020. Open the clamping lock 325 and rotate the rotating handle 321 to open the gripper 324 at the lower end of the screw removal tool 320 using the cylinder 322. Slowly rotate the screw removal tool 320 so that it can naturally grip the screws connecting the upper pipe seat 1020 and the fuel rod 1010 frame. Press the clamping lock 325 to close the gripper 324. Use a torque wrench to rotate in the same direction to unscrew the fixing screws between the upper pipe seat 1020 and the fuel rod 1010 frame. Move the screw removal tool 320 to put the screws into the screw storage bucket. Repeat the above disassembly steps until all the screws on the upper pipe seat 1020 are removed. Use a crane to lift the pipe seat fixing tool 310 and remove the upper pipe seat 1020 from the fuel assembly 1000.

[0061] Taking the installation of the upper tube seat 1020 as an example, the tube seat fixing tool 310 moves the upper tube seat 1020 directly above the fuel rod 1010 to be installed, so that the screw holes in the upper tube seat 1020 correspond one-to-one with the screw holes on the fuel rod 1010; the gripper 324 of the screw removal tool 320 picks up a screw and aligns the screw with one of the screw holes in the upper tube seat 1020, and the screw removal tool 320 is rotated in the same direction with a wrench so that the screw passes between the screw hole in the upper tube seat 1020 and the screw hole in the fuel rod 1010; the above installation steps are repeated until all screws are installed between the screw holes in the upper tube seat 1020 and the screw holes on the fuel rod 1010.

[0062] like Figure 1 and Figure 9 As shown, in one embodiment, the mobile platform 100 includes a connecting base 140 and a first moving mechanism 110. The connecting base 140 is used to mount and fix the drawing tool 200. The connecting base 140 is connected to the output end of the first moving mechanism 110, so that the first moving mechanism 110 can drive the drawing tool 200 to move along a first direction (X direction) through the connecting base 140, thereby realizing the height adjustment of the drawing tool 200. Specifically, as... Figure 9 As shown, the first moving mechanism 110 can be a lead screw motor, including a first motor, a first lead screw 111, and a first nut. The first motor drives the first lead screw 111 to rotate, causing the first nut to rise and fall. The connecting seat 140 is connected to the nut, thus it can rise and fall synchronously with the nut, thereby realizing the raising and lowering of the stick-pulling tool 200. Furthermore, the moving platform 100 also includes a first guide rail 112, and the connecting seat 140 is slidably connected to the first guide rail 112. The first guide rail 112 guides the raising and lowering of the stick-pulling tool 200, making its raising and lowering operation more stable and reliable.

[0063] Furthermore, such as Figure 9 As shown, the mobile platform 100 also includes a second moving mechanism 120. The first moving mechanism 110 and the connecting seat 140 are integrally connected to the second moving mechanism 120. Thus, the second moving mechanism 120 can drive the connecting seat 140 and the rod-pulling tool 200 to move as a whole along the second direction (Y direction), thereby changing the position of the rod-pulling tool 200 along the second direction and aligning it with the fuel rod 1010 in the second direction. The second moving mechanism 120 can be a cylinder, a lead screw motor, etc. The mobile platform 100 is also provided with a second guide rail 121, to which the first moving mechanism 110 is slidably connected. The second guide rail 121 guides the movement of the rod-pulling tool 200 along the second direction, making its movement more stable and reliable.

[0064] like Figure 9As shown, in another embodiment, the mobile platform 100 further includes a third moving mechanism 130. The second moving mechanism 120, the first moving mechanism 110, and the connecting seat 140 are connected to the third moving mechanism 130 via a fixing plate 150. Thus, the third moving mechanism 130 can drive the first moving mechanism 110, the second moving mechanism 120, the connecting seat 140, and the rod-pulling tool 200 to move along a third direction (Z direction), thereby changing the position of the rod-pulling tool 200 along the third direction so that it can be aligned with the fuel rod 1010 in the third direction, facilitating the rod-pulling tool 200 to clamp the fuel rod 1010 at the corresponding position. The second moving mechanism 120 can be a cylinder, a lead screw motor, etc. The mobile platform 100 also includes a third guide rail 131, to which the second moving mechanism 120 is slidably connected via the fixing plate 150. The third guide rail 131 guides the movement of the rod-pulling tool 200 along the third direction, making its movement more stable and reliable.

[0065] Multiple moving mechanisms enable the rod-pulling tool 200 to move in three directions, aligning it with the fuel rods 1010 of the fuel assembly, and then performing the rod-pulling and rod-inserting operations. As shown in the figure, the X direction indicates the first direction, the Y direction indicates the second direction, and the Z direction indicates the third direction.

[0066] like Figures 1 to 5 As shown, in one embodiment, the fuel rod extraction tool 200 includes two grippers 210 for grasping the fuel rod 1010 and a first drive module 230 for driving the grippers 210 to move in a first direction (X direction). The first drive module 230 is connected to the connecting seat 140, and drives the grippers 210 to rise and fall, so that they can contact the fuel rod 1010 more quickly in order to grip the fuel rod 1010.

[0067] like Figures 2 to 5 As shown, the gripper 210 has elasticity that allows it to expand outward and contract inward. Outward expansion allows it to cover the end of the fuel rod 1010, while inward contraction allows the gripper 210 covering the fuel rod 1010 to lock it in place. The end of the gripper 210 has a clamping head 211, which has an arc-shaped structure. This arc-shaped structure can engage with the locking portion 1011 at the end of the fuel rod 1010, allowing the clamping head 211 to firmly hold the fuel rod 1010. Figures 2 to 4 As shown, the cross-section of the snap-fit ​​part 1011 is trapezoidal, which facilitates the snap-fit ​​and clamping of the gripper 210.

[0068] like Figures 2 to 5As shown, in one embodiment, the rod extraction tool 200 further includes a positioning module 220 for contacting the fuel rod 1010 and a second driving module 240 for driving the positioning module 220 to move along a first direction. The positioning module 220 is located between two grippers 210. During the rod extraction process, the second driving module 240 drives the positioning module 220 to move, causing the positioning module 220 to contact the fuel rod 1010. When the positioning module 220 contacts the fuel rod 1010, it can be determined that the rod extraction tool 200 has moved to a suitable position to grip the fuel rod 1010. At this time, the two grippers 210 only need to move towards the middle to clamp the fuel rod 1010 for the next step of extraction. The positioning module 220 prevents the grippers 210 from missing the target. When the rod is inserted by the rod extraction tool 200, the two grippers 210 open outwards, and the second driving module 240 drives the positioning module 220 downwards to push out the fuel rod 1010, facilitating rod removal. The first drive module 230 and the second drive module 240 can be drive cylinders, and the positioning module 220 can be a positioning shaft.

[0069] like Figures 2 to 5 As shown, the stick-pulling tool 200 has four states. The first state is the arc-top position state, which is the state in which the empty gripper 210 moves up and down. Figure 2 The second state is the half-open state, which is the state when fuel rod 1010 is about to be grasped, see... Figure 3 The third state is the gripping position, where the gripper 210 grips the fuel rod 1010 and moves up and down. See [link / description]. Figure 4 The fourth state is the fully open state, which is the state just before fuel rod 1010 is released. See [link / description]. Figure 5 The entire rod-grabbing process is as follows: First, the gripper is in the apex position, allowing the empty gripper 210 to descend and contact the fuel rod 1010. After contact with the fuel rod 1010, the gripper 210 opens to the half-open position, then descends to fully grip the rod and locks to the gripping position. Next, the gripper 210 is raised to completely remove the fuel rod 1010. After removal, the gripper 210 is released to the fully open position. Once the gripper 210 is completely separated from the fuel rod 1010, it is returned to the apex position.

[0070] In some embodiments, the repair system may also include a force sensor (not shown). When the rod-pulling tool 200 clamps the fuel rod 1010 and moves upward to a preset height before stopping, the force sensor can transmit the applied force data to a force analyzer. The force analyzer can then determine whether the fuel rod 1010 has been broken, thus improving the reliability of use.

[0071] like Figure 10As shown, in one embodiment, the fuel assembly repair system 10 further includes an auxiliary hook mechanism 410 for moving the rod-pulling tool 200 to the mobile platform 100, so as to facilitate the installation of the rod-pulling tool 200 onto the mobile platform 100.

[0072] like Figure 10 As shown, in a specific embodiment, the auxiliary hook mechanism 410 includes a sling 411 and a tension gauge 413 disposed on the sling 411. A hook 412 is disposed on the sling 411. The hook 412 is used to connect with the rod-pulling tool 200 and to lift the rod-pulling tool 200 to the mobile platform 100. The tension gauge 413 can record the tension required during the process of lifting the rod-pulling tool 200 to the mobile platform 100.

[0073] In one embodiment, the repair system also includes a storage container (not shown) for temporarily storing the old fuel rod 1010 that has been removed and the new fuel rod 1010 that will be inserted.

[0074] like Figure 11 As shown, in one embodiment, the fuel assembly repair system 10 further includes a pipe socket adapter 420 for connection with a pipe socket. Taking the upper pipe socket 1020 as an example, the upper pipe socket 1020 has a downwardly extending pin hole 1021. The pipe socket adapter 420 is provided with a positioning pin 421 corresponding to the position of the pin hole 1021. The positioning pin 421 is inserted into the pin hole 1021 to realize the connection between the upper pipe socket 1020 and the pipe socket adapter 420. Further, an expansion piece 4211 is provided at the upper end of the positioning pin 421. The diameter of the expansion piece 4211 is slightly larger than the diameter of the positioning pin 421. A snap-fit ​​groove 1022 is provided on the periphery of the top of the pin hole 1021 corresponding to the position of the expansion piece 4211. The pipe socket adapter 420 and the upper pipe socket 1020 are fixed by snap-fitting the expansion piece 4211 and the snap-fit ​​groove 1022. Understandably, in addition to pin hole 1021, it can also be a threaded hole. Correspondingly, locating pin 421 can be replaced with a bolt.

[0075] Specifically, when the upper tube socket 1020 needs to be connected and fixed to the tube socket adapter 420, the expansion plate 4211 expands and engages with the snap-fit ​​groove 1022. When it is necessary to separate the upper tube socket 1020 from the tube socket adapter 420, the expansion plate 4211 retracts to separate the upper tube socket 1020 from the tube socket adapter 420.

[0076] In one embodiment, the fuel assembly repair system 10 further includes an adapter removal and installation tool (not shown) for locking the pipe socket adapter 420 to or loosening the pipe socket adapter 420 from the pipe socket, thereby facilitating the connection and disconnection between the pipe socket and the pipe socket adapter 420. The pipe socket and the pipe socket adapter 420 can be connected by fasteners such as screws. Specifically, the structure of the adapter removal and installation tool can refer to the aforementioned pipe socket removal and installation tool 300, which can include an adapter fixing tool and a screw removal and installation tool. The adapter fixing tool is used to fix the pipe socket adapter 420, and the screw removal and installation tool is used to tighten or loosen the screws between the pipe socket adapter 420 and the pipe socket, which will not be described in detail here. In other embodiments, the adapter removal and installation tool can also adopt a simpler structure, such as a wrench.

[0077] like Figure 11 and Figure 12 As shown, in one embodiment, the fuel assembly repair system 10 further includes an adapter lifting tool 430 for lifting the pipe socket adapter 420 to a target position. The structure of the adapter lifting tool 430 can be referenced to the structure of the upper pipe socket 1020; that is, the adapter lifting tool 430 includes a lifting drive 432 and a lifting section 431. The lifting section 431 is provided with multiple connection holes 4311 for connecting with positioning pins 421 on the pipe socket adapter 420. The lifting drive 432 is used to drive the lifting section 431 to move up and down, causing the lifting section 431 to move closer to or away from the pipe socket adapter 420. Taking the upper pipe seat 1020 as an example, after the multiple connecting screws between the upper pipe seat 1020 and the fuel rod 1010 frame are removed, the upper pipe seat 1020 and the pipe seat adapter 420 are connected through multiple connecting holes 4311 in the adapter lifting tool 430 to the positioning pins 421. Then, in conjunction with the lifting drive component 432, the lifting part 431 is driven to rise and fall, thereby enabling the upper pipe seat 1020 and the pipe seat adapter 420 to be lifted and moved out simultaneously. In other embodiments, the adapter lifting tool can also be a lifting rod, etc.

[0078] like Figure 13 As shown, in one embodiment, the fuel assembly repair system 10 further includes a guide cylinder 440 placed on the moving platform 100, the diameter of which is slightly larger than the outer diameter of the fuel assembly 1000. Considering the relatively long length of the fuel rod 1010, it may break during extraction. Therefore, after the upper tube seat 1020 is removed, the guide cylinder 440 is fitted around the outer periphery of the fuel rod 1010. In this way, the guide cylinder serves two purposes: firstly, it guides the removal and insertion of the fuel rod 1010; secondly, it protects the fuel rod 1010 during extraction, preventing it from breaking and potentially scattering the fuel rod's internal components.

[0079] like Figure 11 and Figure 14 As shown, in one embodiment, the fuel assembly repair system 10 further includes a height measuring tool 450, which is used to measure the height of the pipe seat. Specifically, the height measuring tool 450 is provided with a scale 451. After the upper pipe seat 1020 is connected and fixed to the pipe seat adapter 420, the height of the upper pipe seat 1020 can be recorded by the scale 451, which facilitates direct positioning to the current height for subsequent removal of the upper pipe seat 1020.

[0080] In one embodiment, the fuel assembly repair system 10 also includes a video monitoring mechanism for monitoring the fuel assembly. The video monitoring system can monitor and record the entire repair process for easy review later.

[0081] Understandably, the repair system also includes an electrical cabinet for supplying power to the various electrical components.

[0082] like Figure 15 As shown, further, one embodiment of this application also provides a method for repairing a fuel assembly. Based on the above-described fuel assembly repair system, the method for repairing a fuel assembly includes the following steps:

[0083] S000: Preliminary visual inspection.

[0084] Specifically, based on the location of the fuel assemblies in the waste pool, a fuel rod inspection device is hoisted below the water surface to conduct video inspections and record audio. Any abnormalities detected, such as foreign objects, damage, or deformation, are meticulously recorded to determine if the fuel assemblies meet repair requirements. The inspection device determines whether fuel assemblies require repair and the specific location of the fuel rods requiring repair. The fuel rod inspection device can be an underwater high-definition camera.

[0085] S100. Install the fuel assembly into the fuel basket and remove the fuel assembly's connector.

[0086] Specifically, first, the fuel assembly is hoisted into the fuel basket, ensuring that the Y-angle of the fuel assembly aligns with the Y-angle of the fuel basket during placement. Taking a cube-shaped fuel assembly as an example, the Y-angle is the included angle between two adjacent sides of the fuel assembly. Since the Y-angle of the fuel assembly is known, simply ensuring the Y-angle of the fuel basket coincides with the Y-angle of the fuel assembly is sufficient. Next, the adapter hoisting tool is used to hoist the tube socket adapter to the fuel assembly, and the adapter disassembly tool is used to secure the upper tube socket and adapter to the fuel assembly. Finally, the tube socket disassembly tool is used to disconnect the upper tube socket from the fuel rod.

[0087] S200: Remove the fuel rod to be replaced and insert the new fuel rod into the fuel assembly.

[0088] Specifically, the rod extraction tool is moved above the fuel rod using a mobile platform, and the tool is used to remove the fuel rod to be replaced and insert the new fuel rod into the lower tube seat. The specific structure of the rod extraction tool can be referred to the aforementioned embodiment, and will not be repeated here.

[0089] S300, refueling assembly connector.

[0090] Specifically, the adapter hoisting tool is used to hoist the pipe socket adapter and the upper pipe socket to the fuel assembly; then the pipe socket disassembly and assembly tool is used to connect the upper pipe socket to the fuel rod; and finally, the adapter disassembly and assembly tool is used to disconnect the upper pipe socket from the pipe socket adapter.

[0091] During reassembly, a screw bulging tool can be used to check if the screw has been properly bulged. Specifically, each screw is first reassembled using the first torque, then bulged, and finally a loosening test is performed using the second torque (which is less than the first) to ensure the screw cannot be loosened. It should be noted that the screw is hollow, i.e., it is ring-shaped. The bulging tool is inserted inside the screw, and then the tool is rotated to apply pressure to the inside of the screw, causing it to expand.

[0092] S400, Inspect the fuel assembly.

[0093] Specifically, first install the fuel rod inspection device at an underwater depth of, for example, eight meters below zero. Then, position the rod extraction tool above the inspection device and lower it into the guide hole of the inspection device. Slowly lower the fuel rod and begin collecting eddy current signals; once the eddy current signals are collected, begin high-definition inspection of each fuel rod. Adjust the video settings until the fuel rod image is clear; slowly move the fuel rod up and down to begin video inspection. After one side of the inspection is completed, the fuel rod can be flipped using the flipping assembly until all fuel rods have been inspected.

[0094] Specifically, the inspection device is an eddy current device. The eddy current device generates an eddy current electromagnetic field. The electromagnetic field will produce different waveforms when passing through an intact fuel rod and a damaged fuel rod. Based on this principle, minute breaks in the fuel rod can be detected. By raising and lowering the fuel rod, the fuel rod is passed through the eddy current device in sequence to detect which part of the fuel rod is damaged.

[0095] It should be noted that the above operations are all conducted underwater, such as in boron water. Since the fuel rods release neutrons, which are radioactive, and boron water effectively absorbs these neutrons, it can shield against radiation and improve the safety of the operators.

[0096] The repair system and repair method provided in the above embodiments perform non-destructive testing to inspect each fuel rod in the damaged fuel assembly, identify the damaged fuel rods, and then replace the damaged fuel rods with new fuel rods or other spare fuel rods. After the replacement is completed, the fuel assembly is put back into the reactor, so that damaged fuel assemblies that have not reached the burnup depth can be returned to the reactor for reuse, thereby improving the economics of nuclear power plants.

[0097] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A repair system for fuel assemblies, characterized in that, The fuel assembly (1000) includes two tube seats, one upper tube seat and one lower tube seat; the fuel assembly (1000) also includes a plurality of fuel rods (1010) connected between the upper tube seat and the lower tube seat; the fuel assembly repair system includes: A pipe seat assembly / disassembly tool (300) is used to connect or disconnect the upper pipe seat from the fuel rod (1010); A rod-pulling tool (200) is used to clamp the fuel rod (1010) and insert or remove the fuel rod (1010) from the lower tube seat; A mobile platform (100) is used to install the rod-pulling tool (200) and move the rod-pulling tool (200) to a position above the fuel rod (1010) exposed after the upper pipe seat is disconnected; The rod-pulling tool (200) includes two grippers (210) for gripping the fuel rod (1010); the rod-pulling tool (200) also includes a positioning module (220) for abutting against the fuel rod (1010) and a second driving module (240) for driving the positioning module (220) to move in a first direction, the positioning module (220) being located between the two grippers (210); The fuel assembly repair system also includes a socket adapter (420) for connection with the socket.

2. The fuel assembly repair system according to claim 1, characterized in that, The mobile platform (100) includes: A first moving mechanism (110) is connected to the drawing tool (200) and is used to drive the drawing tool (200) to move along a first direction; The second moving mechanism (120) is connected to the first moving mechanism (110); the second moving mechanism (120) is used to drive the drawing tool (200) to move along the second direction; The third moving mechanism (130) is connected to the second moving mechanism (120); the third moving mechanism (130) is used to drive the drawing tool (200) to move along a third direction; the first direction, the second direction and the third direction are perpendicular to each other.

3. The fuel assembly repair system according to claim 2, characterized in that, The stick-pulling tool (200) includes a first drive module (230) for driving the gripper (210) to move along the first direction, and the first drive module (230) is connected to the first moving mechanism (110).

4. The fuel assembly repair system according to claim 1, characterized in that, The fuel assembly repair system also includes an adapter removal tool for locking the pipe socket adapter (420) to the pipe socket or loosening the pipe socket adapter (420) from the pipe socket.

5. The fuel assembly repair system according to any one of claims 1 to 4, characterized in that, The fuel assembly repair system also includes an auxiliary hook mechanism (410) for moving the pull rod tool (200) to the mobile platform (100).

6. The fuel assembly repair system according to claim 5, characterized in that, The auxiliary hook mechanism (410) includes a sling (411) and a tension gauge (413) disposed on the sling (411). The sling (411) is used to hoist the pull bar tool (200) to the mobile platform (100).

7. A method for repairing a fuel assembly, characterized in that, The fuel assembly repair system according to any one of claims 1 to 6, and the fuel assembly repair method include the following steps: The connection between the tube seat and the fuel rod is disconnected using the tube seat disassembly and assembly tool; The mobile platform moves the rod-pulling tool above the fuel rod, causing the tool to clamp the fuel rod to be replaced and remove it from the tube seat. A new fuel rod is inserted into the tube socket using a rod-pulling tool; The fuel assembly socket is reinstalled using a socket removal and installation tool.

8. The method for repairing fuel assemblies according to claim 7, characterized in that, Following the step of reinstalling the fuel assembly into the connector, the method further includes: Install fuel rod inspection device; Lower the fuel rods and collect eddy current signals; Video inspection.

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