A gripper for gripping nuclear fuel assemblies for nuclear power plants

Abstract

The application belongs to the technical field of nuclear fuel assemblies for nuclear power plants, and particularly relates to a gripper for grabbing a nuclear fuel assembly for a nuclear power plant. The gripper for grabbing a nuclear fuel assembly for a nuclear power plant is free of sharp corners, thereby avoiding damage to the surface of the nuclear fuel assembly or affecting the smooth loading and unloading of the nuclear fuel assembly. The gripper has a self-locking function, so that the gripper cannot be separated from the nuclear fuel assembly during load operation or power-off, and the locking effect during transportation can be further improved. The switch operation of the gripper has a clear position indication, and the control precision for connecting and disconnecting the nuclear fuel assembly is higher, and the reliability is better.

Description

Technical Field

[0001] This application belongs to the technical field of nuclear fuel assemblies for nuclear power plants, and specifically relates to a gripper for gripping nuclear fuel assemblies for nuclear power plants. Background Technology

[0002] The nuclear fuel assemblies inside a nuclear reactor are the power source of a nuclear power plant. Each major overhaul of a nuclear power plant requires a refueling operation, which involves removing a portion of the irradiated fuel assemblies that have reached a certain burn-out depth from the reactor and then installing new fuel assemblies. Irradiated fuel assemblies are highly radioactive materials and must be handled underwater using specialized equipment and tools to meet the corresponding radiation shielding requirements.

[0003] The safe handling of nuclear fuel assemblies is of paramount importance. According to the requirements of HAD102-15-2007 Design of Fuel Loading, Unloading and Storage Systems for Nuclear Power Plants, specially designed grippers are necessary to ensure the safe and reliable handling of nuclear fuel assemblies. The operating environment of these grippers is underwater. If the grippers malfunction, it will prevent the normal conduct of major overhauls at the nuclear power plant and could even trigger a nuclear accident. Therefore, the reliability of the nuclear fuel assembly grippers is of utmost importance. Summary of the Invention

[0004] The purpose of this application is to provide a gripper for grabbing nuclear fuel assemblies used in nuclear power plants, which solves the problem that the operating environment of the nuclear fuel assembly operation gripper is underwater. If the gripper malfunctions, it will prevent the normal conduct of nuclear power plant overhaul work, and may even cause a nuclear accident.

[0005] The technical solution to achieve the purpose of this application is as follows:

[0006] This application provides a gripper for grabbing nuclear fuel assemblies for nuclear power plants. The gripper includes an outer sleeve and an inner sleeve disposed inside the outer sleeve.

[0007] The lower part of the outer sleeve is provided with an inwardly protruding step, and the step is provided with two symmetrical openings so that the two lifting lugs of the nuclear fuel assembly can enter the outer sleeve through the openings and rest on the step; the diameter between the steps is smaller than the diameter at the lifting lugs of the nuclear fuel assembly.

[0008] The inner cylinder can slide up and down inside the outer cylinder, and the diameter of the inner cylinder is smaller than the diameter of the lifting lug of the nuclear fuel assembly, so as to use the weight of the inner cylinder itself to fix the lifting lug of the nuclear fuel assembly at the step.

[0009] Optional,

[0010] The outer sleeve is provided with a curved groove, and the inner sleeve is fixed with a positioning pulley, which moves up and down within the curved groove;

[0011] When the positioning pulley slides downward along the curved groove, it drives the outer sleeve to rotate relative to the inner cylinder, so that the lifting lug of the nuclear fuel assembly enters the outer sleeve from the opening and falls on the step; when the positioning pulley slides upward along the curved groove, the outer sleeve rotates in the opposite direction relative to the inner cylinder, so that the lifting lug of the nuclear fuel assembly moves from the step to the opening to release the nuclear fuel assembly.

[0012] Optional,

[0013] The positioning pulley is connected to the inner cylinder via a pin, bolt, and washer.

[0014] Optional,

[0015] The upper end of the inner cylinder is provided with a connecting mechanism for connecting the material changer via a drive mechanism cable, so that the inner cylinder slides upward under the tension of the drive mechanism cable.

[0016] Optional,

[0017] A sliding cylinder is fixed to the upper and / or lower part of the inner cylinder body to form a friction pair with the inner wall of the outer cylinder.

[0018] Optional,

[0019] The sliding cylinder is fixedly connected to the inner cylinder by a thread or a first pin.

[0020] Optionally, the lower end of the opening is trumpet-shaped.

[0021] Optionally, the outer sleeve and the inner sleeve are symmetrical about the central axis.

[0022] Optionally, the outer sleeve includes: a bearing sleeve, an inner sleeve, a material changer working rod, and a first thrust bearing for connecting the inner sleeve and the material changer working rod;

[0023] The step is located at the lower part of the bearing sleeve;

[0024] The inner sleeve is fixed inside the bearing sleeve by a second pin;

[0025] The material changer working rod has a hollow structure, and the inner cylinder is arranged inside the material changer working rod;

[0026] A boss is formed between the upper and lower halves of the material changing machine working rod. The diameter of the upper half of the material changing machine working rod is larger than that of the lower half. The lower half of the material changing machine working rod is inserted into the inner sleeve, and the upper half of the material changing machine working rod protrudes from the upper end of the bearing sleeve and the inner sleeve. The boss sits on one thrust washer of the first thrust bearing, and the other thrust washer of the first thrust bearing sits on the upper end face of the inner sleeve.

[0027] The curved groove passes through the bearing sleeve, the inner cylinder, and the material changing machine working rod.

[0028] Optional,

[0029] The upper half of the working rod of the material changer is equipped with a guide key for connecting the material changer.

[0030] Optionally, a first indicating component is provided on the outer wall of the bearing sleeve, and a second indicating component and a third indicating component are provided on the outer wall of the upper half of the material changing machine working rod;

[0031] When the positioning pulley slides upward to the top of the curved groove, the first indicator component and the second indicator component are aligned; when the positioning pulley slides downward to the bottom of the curved groove, the first indicator component and the third indicator component are aligned.

[0032] Optionally, the outer sleeve further includes: a guide cylinder and a second thrust bearing for connecting the guide cylinder and the inner sleeve;

[0033] The outer wall of the guide cylinder is provided with an upwardly extending fixing component, which is used to fix the lower end of the working rod of the material changer by a third pin;

[0034] The lower end face of the inner sleeve rests on one thrust washer of the second thrust bearing, and the other thrust washer of the second thrust bearing rests on the upper end face of the fixed component.

[0035] The lower part of the guide cylinder is an open structure, and the upper part is provided with a sealing plate. The lower end of the inner cylinder rests on the sealing plate; the diameter of the open structure is larger than the diameter of the fuel assembly.

[0036] The side wall of the guide cylinder has two guide grooves that correspond one-to-one with the openings, for inserting the two lifting lugs of the fuel assembly; when the positioning pulley slides upward to the top of the curved groove, the guide groove aligns with the corresponding opening.

[0037] Optional,

[0038] The step has two grooves that correspond one-to-one with the guide groove, which are used to accommodate the two lifting lugs of the fuel assembly; when the positioning pulley slides down to the bottom of the curved groove, the guide groove aligns with the corresponding groove.

[0039] Optional,

[0040] The diameter of the upper half of the inner cylinder is greater than the diameter of the lower half of the inner cylinder and the diameter of the lower half of the material changing machine working rod.

[0041] The lower half of the inner cylinder is inserted into the lower half of the material changer's working rod, and the upper half of the inner cylinder is located inside the upper half of the material changer's working rod.

[0042] The beneficial technical effects of this application are as follows:

[0043] (1) This application provides a gripper for grabbing nuclear fuel assemblies for nuclear power plants. It has no sharp edges or corners, which avoids damaging the surface of the nuclear fuel assembly or affecting the smooth loading and unloading of the nuclear fuel assembly. It has a self-locking function, so that the gripper cannot be separated from the nuclear fuel assembly when it is under load or when the power is off, which can further improve the locking effect during transportation. The gripper has clear position indicators for its switching operation, and the control accuracy of connecting and disconnecting the nuclear fuel assembly is higher and the reliability is better.

[0044] (2) This application provides a gripper for grabbing nuclear fuel assemblies for nuclear power plants. All components are designed to be detachable, which makes maintenance convenient, reduces the time for fault analysis and disassembly and maintenance, and lowers equipment maintenance costs and the nuclear radiation dose to workers.

[0045] (3) This application provides a gripper for grabbing nuclear fuel assemblies for nuclear power plants. The opening and closing action can be completed by the linear movement of the inner cylinder. Two positioning pulleys are set on the inner cylinder to reduce the resistance when the inner cylinder moves up and down. At the same time, two axial thrust bearings are set on the outer cylinder to reduce the resistance of the rotational movement of the outer cylinder. This allows the gripper to connect and disconnect nuclear fuel assemblies more quickly and to easily load and unload nuclear fuel assemblies.

[0046] (4) This application provides a gripper for grabbing nuclear fuel assemblies for nuclear power plants. The switching action does not require additional gas or power sources, but is achieved by the weight of the inner cylinder or by overcoming its own weight. This fundamentally eliminates the risk of the gripper becoming unusable due to the failure of additional power sources, solves the problem of the difficulty in controlling additional power sources, and improves the reliability of the nuclear fuel assembly gripper switch.

[0047] (5) This application provides a gripper for grabbing nuclear fuel assemblies for nuclear power plants. The main outer sleeve and inner cylinder are symmetrical along the central axis, making the force more uniform. Practice has proven that it has stable performance in particularly turbid media and is not affected by impurities in spent pool water, thus improving the safety of nuclear fuel assembly operation. Attached Figure Description

[0048] Figure 1 This application provides a schematic diagram of the structure of a gripper for grasping nuclear fuel assemblies used in nuclear power plants, as shown in the embodiments of the present application.

[0049] Figure 2 A schematic diagram of another gripper for grabbing nuclear fuel assemblies for nuclear power plants provided in this application embodiment;

[0050] Figure 3a and Figure 3b These are side and top views of a nuclear fuel assembly.

[0051] In the picture:

[0052] 1-Outer sleeve; 11-Step; 111-Groove; 12-Opening; 13-Curved groove; 14-Bearing sleeve; 141-First indicating component; 15-Inner sleeve; 16-Material changer working rod; 161-Boss; 162-Guide key; 163-Second indicating component; 164-Third indicating component; 171-First thrust bearing; 172-Second thrust bearing; 18-Second pin; 19-Guide cylinder; 191-Fixing component; 192-Third pin; 193-Opening structure; 194-Sealing plate; 195-Guide groove;

[0053] 2-Inner cylinder; 21-Positioning pulley; 22-Connecting mechanism; 23-Sliding cylinder; 24-First pin;

[0054] 3-Nuclear fuel assembly; 31-Lifting lug. Detailed Implementation

[0055] To enable those skilled in the art to better understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0056] The inventors of this application discovered in their research that some current nuclear fuel assembly grippers have complex structures, many parts, and are sensitive to impurities in the pool; they require disassembly for inspection and maintenance, increasing the radiation dose to workers; they have a high failure rate and are difficult to repair; the connection and disconnection actions require external power, which is difficult to control and results in an unstable grip; and the safety devices that prevent nuclear fuel assembly disengagement may fail, posing a risk that the nuclear fuel assembly may accidentally fall during movement.

[0057] Therefore, this application provides an operating gripper for nuclear fuel assemblies used in nuclear power plants. First, the opening and closing action can be completed solely through the linear movement of the inner cylinder. Two positioning pulleys are installed on the inner cylinder to reduce resistance during its vertical movement, and two axial thrust bearings are installed on the outer cylinder to reduce resistance during its rotational movement. This allows the gripper to connect and disconnect nuclear fuel assemblies more quickly, facilitating the loading and unloading of nuclear fuel assemblies. Second, it has no sharp edges or corners, avoiding damage to the surface of the nuclear fuel assembly or hindering its smooth loading and unloading. It has a self-locking function, ensuring that the gripper cannot detach from the nuclear fuel assembly during operation under load or power failure, further improving the locking effect during transportation. The gripper's opening and closing operation has clear position indicators, resulting in higher control precision and better reliability in connecting and disconnecting nuclear fuel assemblies. Third, all components are designed as detachable structures, facilitating maintenance, reducing the time spent on fault analysis and disassembly / repair, lowering equipment maintenance costs, and reducing the radiation dose to personnel. Fourth, the switching action does not require an additional gas or power source; instead, it is achieved through the weight of the inner cylinder itself or by overcoming its own weight. This fundamentally eliminates the risk of the gripper becoming unusable due to a failure of an additional power source, solves the problem of uncontrollable additional power sources, and improves the reliability of the nuclear fuel assembly gripper switch. Fifth, the main outer sleeve and inner cylinder are symmetrical along the central axis, resulting in more even force distribution. Practical experience has proven that it performs stably in particularly turbid media and is not affected by impurities in spent pool water, thus improving the safety of nuclear fuel assembly operation.

[0058] Based on the above, in order to clearly and in detail illustrate the advantages of this application, the specific embodiments of this application will be described below in conjunction with the accompanying drawings.

[0059] See Figure 1 The figure is a schematic diagram of the structure of a gripper for grabbing nuclear fuel assemblies for nuclear power plants, provided in an embodiment of this application.

[0060] This application provides a gripper for grabbing nuclear fuel assemblies for nuclear power plants, comprising: an outer sleeve 1 and an inner sleeve 2 disposed inside the outer sleeve 1;

[0061] The lower part of the outer casing 1 has an inwardly protruding step 11, and two symmetrical openings 12 are provided on the step 11 to allow the two lifting lugs 31 of the nuclear fuel assembly 3 (such as...) Figure 3a and Figure 3b (As shown) It enters the outer casing 1 through the opening 12 and falls on the step 11; the diameter between the steps 11 is smaller than the diameter at the lug 31 of the nuclear fuel assembly 3;

[0062] The inner cylinder 2 can slide up and down inside the outer cylinder 1, and the diameter of the inner cylinder 2 is smaller than the diameter of the lifting lug 31 of the nuclear fuel assembly 3, so as to use the weight of the inner cylinder 2 itself to fix the lifting lug 31 of the nuclear fuel assembly 3 to the step 11.

[0063] It is understandable that when the lifting lug 31 of the nuclear fuel assembly 3 is fixed at the step 11, the nuclear fuel assembly 3 can be moved by lifting the outer sleeve 1, thereby achieving the grasping of the nuclear fuel assembly 3.

[0064] In this embodiment, the gripping does not require additional gas or power sources, but is achieved by the weight of the inner cylinder 2 itself or by overcoming its own weight. This fundamentally eliminates the risk of the gripper becoming unusable due to the failure of an additional power source, solves the problem of the difficulty in controlling an additional power source, and improves the reliability of the nuclear fuel assembly gripper switch.

[0065] In addition, the weight of the inner cylinder 2 itself fixes the lifting lug 31 of the nuclear fuel assembly 3 to the step 11. The inner cylinder 2 cannot overcome its own weight and the force between the nuclear fuel assembly 3 and the outer cylinder 1 to move upward. The gripper always maintains a self-locking state to prevent the nuclear fuel assembly 3 from falling during lifting and transportation. That is, the gripper and the nuclear fuel assembly 3 cannot be separated in an abnormal position, so that the gripper has a self-locking function. When running under load or when power is cut off, the gripper and the nuclear fuel assembly 3 cannot be separated, which can further improve the locking effect during transportation.

[0066] Understandably, the smooth outer surface of the outer sleeve 1 has no sharp edges or corners, which avoids damaging the surface of the nuclear fuel assembly 3 or affecting the smooth loading and unloading of the nuclear fuel assembly 3.

[0067] In one example, the lower end of the opening 12 is funnel-shaped to facilitate the insertion of the nuclear fuel assembly 3.

[0068] In another example, the outer sleeve 1 and the inner sleeve 2 are symmetrical along the central axis, making the stress distribution more uniform. Practical experience has shown that it operates stably in particularly turbid media and is not affected by impurities in spent fuel pool water, thus improving the safety of nuclear fuel assembly 3 operation.

[0069] In order to guide the rotation of the outer sleeve 1 to facilitate the fixing of the lifting lug 31 of the nuclear fuel assembly 3 to the step 11, in some possible implementations of the embodiments of this application, the outer sleeve 1 is provided with a curved groove 13, and the inner cylinder 2 is fixed with a positioning pulley 21, which moves up and down in the curved groove 13.

[0070] When the positioning pulley 21 slides downward along the curved groove 13, it drives the outer sleeve 1 to rotate relative to the inner cylinder 2, so that the lifting lug 31 of the nuclear fuel assembly 3 enters the outer sleeve 1 from the opening 12 and falls on the step 11; when the positioning pulley 21 slides upward along the curved groove 13, the outer sleeve 1 rotates in the opposite direction relative to the inner cylinder 2, so that the lifting lug 31 of the nuclear fuel assembly 3 moves from the step to the opening 11 to release the nuclear fuel assembly 3.

[0071] It should be noted that the inner cylinder 2 is guided to move up and down inside the outer cylinder 1 by the curved groove 13 and the positioning pulley 21, which drives the outer cylinder 1 to rotate, thereby realizing the opening and closing action of the gripper. That is, the connection and disconnection operation between the gripper and the nuclear fuel assembly 3 can be completed by the linear movement of the inner cylinder 1. This allows the gripper to connect and disconnect the nuclear fuel assembly 3 more quickly, and makes it easier to load and unload the nuclear fuel assembly 3.

[0072] As an example, the positioning pulley 21 is connected to the inner cylinder 2 by a pin and bolt washer (not shown in the figure).

[0073] To facilitate the unloading of nuclear fuel assembly 3, in one example, the upper end of the inner cylinder 2 is provided with a connecting mechanism 22 for connecting the refueling machine via a drive mechanism cable, so that the inner cylinder 2 slides upward by the tension of the drive mechanism cable.

[0074] In another example, in order to reduce the resistance when the inner cylinder 2 moves up and down, a sliding cylinder 23 is fixed to the upper and / or lower part of the inner cylinder 2 to form a friction pair with the inner wall of the outer cylinder 1.

[0075] In practice, the sliding cylinder 23 can be fixedly connected to the inner cylinder 2 by threads or the first pin 24.

[0076] In some possible implementations of the embodiments of this application, see also... Figure 1 The outer sleeve 1 may specifically include: a bearing sleeve 14, an inner sleeve 15, a material changer working rod 16, and a first thrust bearing 171 for connecting the inner sleeve 15 and the material changer working rod 16;

[0077] Step 11 is provided at the lower part of the bearing sleeve 14;

[0078] The inner sleeve 15 is fixed inside the bearing sleeve 14 by the second pin 18;

[0079] The working rod 16 of the material changer has a hollow structure, and the inner cylinder 2 is installed inside the working rod 16 of the material changer.

[0080] A boss 161 is formed between the upper and lower halves of the material changing machine working rod 16. The diameter of the upper half of the material changing machine working rod 16 is larger than that of the lower half. The lower half of the material changing machine working rod 16 is inserted into the inner sleeve 15, and the upper half of the material changing machine working rod 16 protrudes from the upper end of the bearing sleeve 14 and the inner sleeve 15. The boss 161 sits on one thrust washer of the first thrust bearing 171, and the other thrust washer of the first thrust bearing sits on the upper end face of the inner sleeve 15.

[0081] The curved groove 13 passes through the bearing sleeve 14, the inner cylinder 15, and the material changing machine working rod 16.

[0082] In this embodiment, a first thrust bearing 171 is provided on the outer sleeve 1 to reduce the resistance of the rotational movement of the outer sleeve 1, which allows the gripper to connect and disconnect the nuclear fuel assembly 3 more quickly and facilitates the loading and unloading of the nuclear fuel assembly 3. The upper half of the refueling machine working rod 16 protrudes from the upper end of the bearing sleeve 14 and the inner sleeve 15 to facilitate the connection of the refueling machine.

[0083] As an example, the upper half of the working rod 16 of the material changer is provided with a guide key 162 for connecting the material changer.

[0084] In some possible implementations of the embodiments of this application, such as Figure 2 As shown, a first indicating component 141 is provided on the outer wall of the bearing sleeve 14, and a second indicating component 163 and a third indicating component 164 are provided on the outer wall of the upper half of the material changing machine working rod 16.

[0085] When the positioning pulley 21 slides upward to the top of the curved groove 13, the first indicator component 141 and the second indicator component 163 are aligned; when the positioning pulley 21 slides downward to the bottom of the curved groove 13, the first indicator component 141 and the third indicator component 164 are aligned.

[0086] It is understandable that by using the first indicator component 141, the second indicator component 163 and the third indicator component 164, the opening and closing operation of the gripper can be clearly indicated, and the control precision for connecting and disconnecting the nuclear fuel assembly 3 is higher and the reliability is better.

[0087] In some possible implementations of the embodiments of this application, in order to facilitate the connection of nuclear fuel assembly 3 and outer sleeve 1, a guide cylinder 19 and a second thrust bearing 172 for connecting the guide cylinder 19 and inner sleeve 15 are also included.

[0088] The outer wall of the guide cylinder 19 is provided with an upwardly extending fixing component 191, which is used to fix it to the lower end of the material changer working rod 16 by a third pin 192;

[0089] The lower end face of the inner sleeve 15 rests on one thrust washer of the second thrust bearing 172, and the other thrust washer of the second thrust bearing 172 rests on the upper end face of the fixed component 191.

[0090] The lower part of the guide tube 19 is an open structure 193, and the upper part is provided with a sealing plate 194. The lower end of the inner tube 2 rests on the sealing plate 194. The diameter of the open structure 193 is larger than the diameter of the nuclear fuel assembly 3.

[0091] The side wall of the guide tube 19 has two guide grooves 195 that correspond one-to-one with the opening 12, for inserting the two lifting lugs 31 of the nuclear fuel assembly 3; when the positioning pulley 21 slides upward to the top of the curved groove 13, the guide groove 195 is aligned with the corresponding opening 12.

[0092] In this embodiment of the application, a second thrust bearing 172 is provided on the outer sleeve 1, which can reduce the resistance of the rotational movement of the outer sleeve 1, enabling the gripper to connect and disconnect the nuclear fuel assembly 3 more quickly, and making it easier to load and unload the nuclear fuel assembly 3.

[0093] Understandably, when the positioning pulley 21 slides upward to the top of the curved groove 13, the guide groove 195 aligns with the corresponding opening 12, and the two lifting lugs 31 of the nuclear fuel assembly 3 are inserted into the guide groove 195. As the outer sleeve 1 rotates, the guide groove 195 drives the two lifting lugs 31 of the nuclear fuel assembly 3 to rotate, causing them to fall onto the step 11. The inner sleeve 2 falls onto the sealing plate 194, so that the guide cylinder 19 fixes the two lifting lugs 31 of the nuclear fuel assembly 3 onto the step 11, preventing them from falling off.

[0094] In one example, to improve the fixing effect of the lug 31, two grooves 111 corresponding to the guide groove 195 are provided on the step 11 to accommodate the two lugs 31 of the nuclear fuel assembly 3; when the positioning pulley 21 slides down to the bottom of the curved groove 13, the guide groove 195 aligns with the corresponding groove 111, so that the lower end of the lug 31 is stuck in the groove 111.

[0095] In another example, to improve the fixing effect of the lifting lug 31, the diameter of the upper half of the inner cylinder 2 is larger than the diameter of the lower half of the inner cylinder 2 and the diameter of the lower half of the material changer working rod 16; the lower half of the inner cylinder 2 is inserted into the lower half of the material changer working rod 16, and the upper half of the inner cylinder 2 is set inside the upper half of the material changer working rod 16. This also facilitates the connection between the material changer and the inner cylinder 2.

[0096] It should also be noted that the gripper provided in this application for grabbing nuclear fuel assemblies for nuclear power plants has all its components designed as detachable structures, which facilitates maintenance, reduces the time for fault analysis and disassembly and maintenance, and lowers equipment maintenance costs and the nuclear radiation dose to workers.

[0097] In actual use, after the opening 11 at the bottom of the outer sleeve 1 is guided and positioned with the lifting lug 31 at the head of the nuclear fuel assembly 3, when the inner cylinder 2 moves downward by its own weight, the positioning pulley 21 rolls downward in the curved groove 13, and the outer sleeve 1 rotates counterclockwise. When the first indicator component 141 on the bearing sleeve 14 reaches the closed position (i.e., aligned with the third indicator component 164), the nuclear fuel assembly gripper closes and connects with the nuclear fuel assembly 3, and the lifting lug 31 of the nuclear fuel assembly 3 enters the groove 111 of the step 11 at the bottom of the outer sleeve 1; when the inner cylinder 2 moves upward by the tension of the upper steel cable, the positioning pulley 21 rolls upward in the curved groove 13, and the outer sleeve 1 rotates clockwise. When the first indicator component 141 on the bearing sleeve 14 reaches the open position (i.e., aligned with the second indicator component 163), the nuclear fuel assembly gripper opens and disengages from the nuclear fuel assembly 3, and the lifting lug 31 of the nuclear fuel assembly 3 enters the opening 12 of the step 11.

[0098] The following example illustrates in detail the specific working process of a gripper for grabbing nuclear fuel assemblies used in nuclear power plants, as provided in the embodiments of this application.

[0099] The application provides an embodiment of a gripper for grabbing nuclear fuel assemblies used in nuclear power plants. The installation steps mainly consist of the following stages:

[0100] 1) Assemble and install the inner cylinder 2, outer cylinder 1, positioning pulley 21, first thrust bearing 171 and second thrust bearing 172;

[0101] 2) Install the assembled components onto the working rod 16 of the material changer and connect the drive mechanism steel cable;

[0102] 3) The stability of the gripper was tested by gripping a simulated fuel assembly after the refueling machine was powered on;

[0103] 4) When grabbing the fuel assembly 3, after the guide cylinder 19 at the bottom of the outer sleeve 1 is guided and positioned by the lifting lug 31 at the head of the nuclear fuel assembly 3, the inner cylinder 2 moves downward by its own weight, driving the positioning pulley 21 to roll downward in the curved groove 13. The outer sleeve 1 rotates counterclockwise. When the positioning pulley 21 reaches the bottom of the curved groove 13, the nuclear grabber is connected to the nuclear fuel assembly and the lifting lug 31 of the nuclear fuel assembly 3 enters the groove 111 of the bottom step 11 of the outer sleeve 1.

[0104] 5) When the fuel assembly is released, the inner cylinder 2 moves upward by the tension of the drive mechanism cable, the positioning pulley 21 rolls upward in the curved groove 13, and the outer sleeve 1 rotates clockwise. When the positioning pulley 21 reaches the top of the curved groove 13, the gripper opens and disengages from the nuclear fuel assembly 3, and the lifting lug 31 of the nuclear fuel assembly 3 enters the opening 12 of the step 11.

[0105] 6) After checking that the simulated components are correct, move the refueling machine to the nuclear fuel assembly storage location to retrieve the nuclear fuel assembly.

[0106] The present application has been described in detail above with reference to the accompanying drawings and embodiments. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present application. All content not described in detail in this application can be derived from existing technology.

Claims

1. A gripper for gripping a nuclear fuel assembly for nuclear power plants, characterized in that, The grabber comprises an outer sleeve and an inner sleeve body arranged inside the outer sleeve; The lower part of the outer sleeve is provided with a ring of steps protruding inwardly, and two symmetrical openings are arranged on the steps to allow two lugs of a nuclear fuel assembly to enter the outer sleeve from the openings and fall on the steps; the diameter between the steps is smaller than the diameter of the lugs of the nuclear fuel assembly; The inner sleeve body is slidable up and down in the outer sleeve, and the diameter of the inner sleeve body is smaller than the diameter of the lugs of the nuclear fuel assembly, so as to fix the lugs of the nuclear fuel assembly at the steps by using the gravity of the inner sleeve body itself; A curved groove is formed on the outer sleeve, and a positioning pulley is fixed on the inner sleeve body and moves up and down in the curved groove; When the positioning pulley slides downward along the curved groove, the outer sleeve rotates relative to the inner sleeve body, so that the lugs of the nuclear fuel assembly fall on the steps after entering the outer sleeve from the openings; when the positioning pulley slides upward along the curved groove, the outer sleeve rotates in the opposite direction relative to the inner sleeve body, so that the lugs of the nuclear fuel assembly move from the steps to the openings to release the nuclear fuel assembly; The positioning pulley is connected to the inner sleeve body by a pin shaft and a bolt gasket; A sliding cylinder is fixed to the upper part and / or lower part of the inner sleeve body to form a friction pair with the inner wall of the outer sleeve; The sliding cylinder is fixedly connected to the inner sleeve body by threads or a first pin; The lower end of the opening is in the shape of a horn; The outer sleeve and the inner sleeve body are symmetrical along a central axis.

2. The gripper for gripping a nuclear fuel assembly for nuclear power plants according to claim 1, characterized in that, The outer sleeve comprises a bearing sleeve, an inner sleeve, a refueling machine working rod, and a first thrust bearing for connecting the inner sleeve and the refueling machine working rod; The steps are arranged on the lower part of the bearing sleeve; The inner sleeve is fixed in the bearing sleeve by a second pin; The refueling machine working rod is a hollow structure, and the inner sleeve is arranged in the refueling machine working rod; A boss is formed between the upper half and the lower half of the refueling machine working rod, and the diameter of the upper half of the refueling machine working rod is greater than that of the lower half; the lower half of the refueling machine working rod is inserted into the inner sleeve, and the upper half of the refueling machine working rod protrudes from the upper end of the bearing sleeve and the inner sleeve; the boss is seated on one thrust washer of the first thrust bearing, and the other thrust washer of the first thrust bearing is seated on the upper end surface of the inner sleeve; The curved groove penetrates through the bearing sleeve, the inner sleeve, and the refueling machine working rod.

3. The grabber for grabbing a nuclear fuel assembly for a nuclear power plant according to claim 2, wherein The upper half of the refueling machine working rod is provided with a guide key for connecting a refueling machine.

4. The gripper for gripping a nuclear fuel assembly for nuclear power plants according to claim 2, characterized in that, A first indicating component is arranged on the outer wall of the bearing sleeve, and a second indicating component and a third indicating component are arranged on the outer wall of the upper half of the refueling machine working rod. When the positioning pulley slides up to the top end of the curve slot, the first indicating component and the second indicating component are aligned; when the positioning pulley slides down to the bottom end of the curve slot, the first indicating component and the third indicating component are aligned.

5. The gripper for gripping a nuclear fuel assembly for nuclear power plants according to claim 2, characterized in that, The outer sleeve further comprises a guide cylinder and a second thrust bearing for connecting the guide cylinder and the inner sleeve; An outer wall of the guide cylinder is provided with a fixed component extending upward, for being fixed to the lower end of the refueling machine working rod by a third pin; A lower end surface of the inner sleeve is seated on one thrust washer of the second thrust bearing, and another thrust washer of the second thrust bearing is seated on an upper end surface of the fixed component; A lower part of the guide cylinder is of an open structure, and an upper part is provided with a sealing plate, and a lower end of the inner cylinder body falls on the sealing plate; a diameter of the open structure is greater than a diameter of the nuclear fuel assembly; A side wall of the guide cylinder is provided with two guide slots corresponding to the openings, for inserting two lugs of the nuclear fuel assembly; when the positioning pulley slides up to the top end of the curve slot, the guide slots are aligned with the corresponding openings.

6. The grab for grabbing the nuclear fuel assembly for nuclear power plants according to claim 5, characterized in that, Two grooves corresponding to the guide slots are formed on the step, for accommodating the two lugs of the nuclear fuel assembly; when the positioning pulley slides down to the bottom end of the curve slot, the guide slots are aligned with the corresponding grooves.

7. The grab for grabbing the nuclear fuel assembly for nuclear power plants according to claim 2, characterized in that, A diameter of the upper half of the inner cylinder body is greater than a diameter of the lower half of the inner cylinder body and a diameter of the lower half of the refueling machine working rod; The lower half of the inner cylinder body is inserted into the lower half of the refueling machine working rod, and the upper half of the inner cylinder body is arranged in the upper half of the refueling machine working rod.

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