A nuclear fuel rod inner can tube through-pipe cap removing apparatus and method

Abstract

The application provides a nuclear fuel rod inner cladding tube penetrating cap taking device, which comprises a taking guide cap mechanism installed at the end of an outer cladding tube transmission frame, the taking guide cap mechanism has a back-and-forth air cylinder, the back-and-forth air cylinder is connected with a guide sleeve, the guide sleeve has an inner cavity and a guide cap clamp jaw is arranged in the inner cavity to grab a guide cap, a slot is arranged on the guide sleeve, a top block is fixedly installed on the outer cladding tube transmission frame, the end of the top block penetrates through the slot of the guide sleeve and can slide in the guide cap clamp jaw to support the claw of the guide cap clamp jaw. In addition, the application also provides a nuclear fuel rod inner cladding tube penetrating cap taking method. The application can not only complete the guidance of the inner cladding tube penetrating process, but also does not need manual intervention to take the cap, thereby improving the operation continuity.

Description

Technical Field

[0001] This invention relates to the field of nuclear fuel rod manufacturing technology, and in particular to a device and method for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod. Background Technology

[0002] The nuclear fuel rods involved in this invention comprise inner and outer zirconium alloy cladding tubes and annular fuel pellets therein, requiring the assembly of all three. Chinese patent "A Method for Assembling Annular Fuel Elements" (CN201611218765.8) describes a method for inserting the inner cladding tube using a guide head. The assembly method is as follows: first, the annular pellets are inserted one by one into the outer cladding tube; then, the guide head is inserted into one end of the inner cladding tube; next, the end of the inner cladding tube with the guide head is inserted into the annular pellet; the guide head is removed; and finally, upper and lower end plugs are installed to complete the fuel rod welding.

[0003] The guide head of this invention cannot be removed automatically and requires specially assigned personnel to complete the removal operation. Manual removal makes it difficult to ensure the coaxiality of the guide head and the tube during removal, especially when the guide head and the inner shell tube are slightly tight, making removal difficult and potentially applying radial force to the inner wall of the annular core. Summary of the Invention

[0004] The purpose of this invention is to provide a device and method for inserting and removing the guide cap of the inner cladding tube of a nuclear fuel rod, so as to realize the automatic removal of the guide cap after the inner cladding tube is inserted.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A device for removing the cap from the inner cladding tube of a nuclear fuel rod includes a guide cap removal mechanism installed at the end of an outer cladding tube transfer frame. The guide cap removal mechanism has an advance / retreat cylinder connected to a guide sleeve. The guide sleeve has an inner cavity and a guide cap gripper is provided in the inner cavity for gripping the guide cap. The guide sleeve has a slot. A top block is fixedly installed on the outer cladding tube transfer frame. The end of the top block passes through the slot of the guide sleeve and can slide within the guide cap gripper to open the gripper of the guide cap.

[0007] As one possible implementation, the guide sleeve has a square plate structure at one end for connecting the infeed and retractable cylinders, and a shoulder structure at the other end for positioning.

[0008] As one possible implementation, the square plate structure has four through holes for connecting the adapter plate.

[0009] As one possible implementation, rectangular slots are provided on both the top and bottom of the guide sleeve, and the top block is inserted into the middle of the guide sleeve from the rectangular slot on the bottom.

[0010] As one feasible approach, the end of the guide sleeve has a shoulder structure, which is used to block the outer shell tube and the annular core block during the process of inserting the inner shell tube and removing the guide cap.

[0011] As one feasible approach, the inner bore of the guide sleeve is composed of three sections of different diameters: a first inner bore, a second inner bore, and a third inner bore. The first inner bore accommodates the end ring of the guide cap claw and provides axial positioning. The second inner bore accommodates the claw hook portion of the guide cap claw. The third inner bore is used to allow the inner casing tube with the guide cap to pass through. The second inner bore and the third inner bore are transitioned by a small-diameter section.

[0012] As one possible implementation, the diameter of the end ring of the guide cap claw is larger than the diameter of the claw hook portion. The end ring of the guide cap claw is axially positioned within the first inner hole of the guide sleeve.

[0013] As one feasible approach, the guide cap gripper is a two-lobed claw structure, which is made by milling grooves on a hollow ring. The width of the straight groove section in the middle is greater than that of the transition section at the end. Therefore, when the straight groove section in the middle of the guide cap gripper moves along the top block, the claw part will not be opened up. However, when the transition section at the end moves along the top block, the gripper will be opened up by the top block. Each edge of the claw part is blunted and smoothly transitioned, and a claw is machined at the end of each lobe.

[0014] As one feasible approach, the tube insertion and cap removal device further includes an outer shell tube transfer frame and an inner shell tube transfer frame. The outer shell tube transfer frame and the inner shell tube transfer frame are installed in a straight line on a horizontal ground. Both are aluminum profile frames. By adjusting the overall height of the frame, the single inner shell tube to be inserted is made concentric with the outer shell tube, which facilitates the insertion of the inner shell tube into the outer shell tube. The cap removal guide mechanism is installed on the outer shell tube transfer frame. Its guide sleeve height is concentric with the outer shell tube, and its axial direction is located on the side where the inner shell tube exits the outer shell tube.

[0015] As one feasible approach, the guide cap includes a fitting part, a guiding part, and a gripping part. The outer diameter of the fitting part matches the inner diameter of the inner casing tube and is chamfered to facilitate insertion into the inner casing tube. The guiding part has a conical transition surface, which serves as a guide and self-aligning element during tube insertion. The gripping part is a T-shaped structure with a guide head, and its diameter is smaller than the outer diameter of the inner casing tube.

[0016] In addition, the present invention also provides a method for removing the cap from the inner cladding tube of a nuclear fuel rod, comprising the following steps:

[0017] Step 1: After the outer shell tube with the ring core block is positioned on the outer shell tube transfer frame, the cylinder piston of the guide cap mechanism extends, so that the guide sleeve head extends into the outer shell tube.

[0018] Step 2: Install the guide cap at the head of the inner shell and start the developed control program to insert the inner shell tube into the outer shell tube;

[0019] Step 3: After the guide cap moves into the guide sleeve, it is hooked onto the guide cap clamp.

[0020] Step 4: The cylinder piston of the guide cap removal mechanism retracts, and the internal top block opens the guide cap clamp, causing the guide cap to fall automatically into the cap receiving container. At the same time, the guide sleeve of the guide cap removal mechanism retracts with the cylinder piston and disengages from the outer casing tube.

[0021] Compared with the prior art, the device and method for removing the cap after inserting the inner cladding tube of a nuclear fuel rod provided by the present invention have the following advantages:

[0022] This invention can guide the process of inserting the inner casing tube without requiring manual intervention in the cap removal action, thus improving the continuity of operation.

[0023] This invention reduces human intervention in the cap removal process, better ensures the cleanliness of the casing surface, and reduces radial stress on the annular core block. Attached Figure Description

[0024] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the technical description will be briefly introduced below.

[0025] Figure 1 A schematic diagram of a fuel rod structure provided for the prior art;

[0026] Figure 2 This is a schematic diagram of the guide cap structure provided by the present invention;

[0027] Figure 3 This is a front view of the guide cap taking mechanism provided by the present invention;

[0028] Figure 4 This is a top view of the guide cap taking mechanism provided by the present invention;

[0029] Figure 5 A top view of the guide sleeve provided by the present invention;

[0030] Figure 6 for Figure 5 A cross-sectional view along plane AA;

[0031] Figure 7 A side view of the guide sleeve provided by the present invention;

[0032] Figure 8 This is a schematic diagram of the structure of the guide cap gripper provided by the present invention;

[0033] Figure 9 A side view of the guide cap gripper provided by the present invention;

[0034] Figure 10 The diagram shows the automatic plug-removing action provided by the present invention, in which both the outer shell tube and the inner shell tube have been fed into place, and the gripping part of the guide cap is stuck in the claw hook of the guide cap clamp. Figure 11 The diagram illustrates the automatic plug-removing action provided by the present invention, in which the piston of the forward and backward cylinder retracts and the guide cap has been removed;

[0035] Figure 12 This is a schematic diagram of the overall layout of the tube insertion and cap removal device provided by the present invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Outer shell tube; 2. Annular core block; 3. Inner shell tube; 4. Advancing / retracting cylinder; 5. Guide sleeve; 6. Guide cap gripper; 7. Top block; 8. Adapter plate; 9. Outer shell tube transmission frame; 10. Inner shell tube transmission frame; 11. Guide cap removal mechanism; 12. Inner shell tube insertion drive mechanism; 13. Advancing / retracting cylinder piston; 14. Guide cap;

[0038] 51. Square plate structure; 52. Shoulder structure; 53. Rectangular groove; 54. First inner hole; 55. Second inner hole; 56. Third inner hole; 57. Small diameter hole section; 58. Assembly part; 59. Guide part; 60. Gripping part; 61. End ring; 62. Claw hook part; 63. Claw; 64. Middle straight groove section; 65. End transition section. Detailed Implementation

[0039] The following detailed description provides further details on specific implementation methods.

[0040] To facilitate understanding, a brief introduction to fuel rods will be given first. For example... Figure 1 As shown, a certain fuel rod consists of two layers of zirconium alloy cladding, referred to as the outer cladding tube 1 and the inner cladding tube 3, respectively. The fuel pellet is a ring-shaped structure located between the two cladding tubes, referred to as the ring pellet 2. During assembly, the ring pellet 2 is first inserted into the outer cladding tube 1, and then the inner cladding tube 3 is passed through the inner hole of the ring pellet 2. Due to the long insertion distance and the fact that the path is formed by splicing the inner walls of multiple ring pellets, a specially designed inner cladding tube guide cap is required to ensure smooth insertion, prevent damage to the inner wall of the ring pellet 2 and the opening of the inner cladding tube 3, and reduce personnel intervention.

[0041] like Figures 2 to 12 As shown, the present invention provides a device for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod, comprising a guide cap, a guide cap removal mechanism, an outer cladding tube transfer frame, and an inner cladding tube transfer frame. The guide cap removal mechanism is installed at the tail end of the outer cladding tube transfer frame.

[0042] like Figure 2As shown, the guide cap includes a mounting part 58, a guiding part 59, and a gripping part 60. The mounting part 58 can be inserted into the inner shell tube 3, and after mounting, the outer diameter of the guide cap is the same as the outer diameter of the inner shell 3. The guiding part 59 has a conical transition surface, which plays a guiding and self-aligning role during tube insertion and allows the guide cap to easily enter the guide cap gripper 6. The gripping part is a T-shaped structure with a guide head. Because its diameter is smaller than the outer diameter of the inner shell tube 3, it will not affect the tube insertion process.

[0043] like Figure 3 and Figure 4 As shown, the guide cap taking mechanism includes an advancing / retracting cylinder 4, a guide sleeve 5, a guide cap gripper 6, a top block 7, and a transition plate 8. The cylinder body of the advancing / retracting cylinder 4 and the top block 7 are fixed to the outer casing tube transmission frame 9 and are immovable structures. The guide cap gripper 6 is assembled inside the guide sleeve 5, and the two are connected to the piston rod 13 of the advancing / retracting cylinder 4 through the transition plate 8, and can move back and forth with the piston rod 13. The height of the guide sleeve 5 is made to match the height of the outer casing tube 1 by adjusting the height of the advancing / retracting cylinder 4. The head of the top block 7 passes through the inner cavity of the guide sleeve 5 and the guide cap gripper 6 and can slide within them.

[0044] The guide sleeve 5 provides space to accommodate the guide cap clamp 6 and the top block 7. The guide sleeve 5 is made of stainless steel and the main body is a hollow cylindrical structure.

[0045] like Figures 5 to 7 As shown, one end of the guide sleeve 5 is machined into a square plate structure 51 with four through holes for connection with the adapter plate 8 of the infeed and retractable cylinder. The other end of the guide sleeve 5 has a shoulder structure 52 on the outside. The end of the outer casing tube 1 is blocked by the shoulder structure 52 of the guide sleeve 5, which can prevent the annular core block 2 from being pushed out of the outer casing tube during the insertion of the inner casing tube 3. Rectangular slots 53 are opened at the top and bottom of the guide sleeve 5, and the top block 7 is inserted into the middle of the guide sleeve 5 from the rectangular slot 53 at the bottom.

[0046] like Figure 6 As shown, the inner hole of the guide sleeve 5 is composed of three sections with different inner diameters. The first inner hole 54 near the adapter plate can accommodate the end ring 61 of the guide cap claw 6 and position it axially; the longer second inner hole 55 in the middle can accommodate the claw hook portion 62 of the guide cap claw 6; the third inner hole 56 at the other end is used to allow the inner shell tube 3 with the guide cap to pass through. The second inner hole 55 and the third inner hole 56 are transitioned by a small diameter hole section 57, so that the guide portion 59 of the guide cap stops exactly at the orifice, but the gripping portion 60 of the guide cap can be fully inserted into the guide cap claw 6.

[0047] like Figure 8 and Figure 9As shown, the guide cap chuck 6 has a circular ring structure, with its end ring 61 having a slightly larger diameter than the claw hook portion 62. The end ring 61 can be axially positioned within the inner hole of the guide sleeve 5. The two claw hook portions 62 of the guide cap chuck 6 are formed by milling grooves on a hollow ring. The gap width of the middle straight groove section 64 is greater than the gap width of the end transition section 65. Therefore, when the middle straight groove section 64 moves along the top block 7, it will not cause the claw hook portion 62 to be opened. However, when its transition section moves along the top block 7, the claw hook portion 62 will be opened by the top block 7 through the transition section 65. During milling, each edge of the groove is blunted and smoothly transitioned, and a claw 63 is machined at the end of each edge. When assembling the guide cap chuck 6, the middle straight groove section 64 must be aligned with the rectangular groove 53 of the guide sleeve 5 to facilitate the passage of the top block 7.

[0048] like Figure 10 and Figure 11 As shown, in the initial stage, the piston rod 13 of the forward / reverse cylinder 4 extends, the top block 7 is located in the middle straight groove section 64 of the guide cap clamp 6, and the claw hook portion 62 of the guide cap clamp 6 is in a natural state. After the inner casing tube 3 is assembled with the guide cap 14, it moves towards the guide cap clamp 6 under the action of the inner casing tube drive mechanism 12. When the gripping portion 60 of the guide cap 14 slides into the claw 63 of the guide cap clamp 6, it is hooked by the claw 63. At this time, under the control of the program, the piston rod 13 of the forward and backward cylinder 4 returns, driving the guide sleeve 5 and the guide cap pawl 6 to return, thereby pulling the guide cap 14 off the inner shell tube 3, and the entire mechanism and the guide cap 14 are separated from the inner shell tube 3; at the same time, during the return process, the guide sleeve 5 and the guide cap pawl 6 always move along the top block 7. When the end transition section 65 of the guide cap pawl 6 meets the top block 7, the claw hook part 62 is opened, and the claw 63 releases the guide cap 14. In the instant of continuing to retreat, the guide cap 14 automatically falls to the bottom.

[0049] Preferably, the guide cap gripper 6 is made of spring steel, which has the advantage of good elasticity.

[0050] like Figure 12 As shown, the guide cap retrieval mechanism 11 is part of the tube insertion and cap retrieval device, installed at the end of the outer casing tube transfer frame 9. The entire tube insertion and cap retrieval device also includes two parts: the outer casing tube transfer frame 9 and the inner casing tube transfer frame 10. The outer casing tube transfer frame is used to store, transfer, and position the outer casing tube, and the guide cap retrieval mechanism is installed at its tail end. The inner casing tube transfer frame is used to store and transfer the inner casing tube, and an inner casing tube insertion drive mechanism is installed on it. The outer casing tube transfer frame 9 and the inner casing tube transfer frame 10 are installed in a straight line on a horizontal ground, both being aluminum profile frames. By adjusting the overall height of the frames, the single inner and outer casing tubes to be inserted are made concentric, facilitating the insertion of the inner casing tube into the outer casing tube. The guide cap retrieval mechanism is installed on the outer casing tube transfer frame, and its guide sleeve height is the same as that of the outer casing tube, with its axial direction at the tube insertion position.

[0051] The outer casing tube 1 is fed individually to the insertion station by the tube-picking mechanism of the outer casing tube transfer frame 9 and axially positioned. Then, it is positioned on the outer casing tube transfer frame 9. The guide sleeve 5 of the guide cap removal mechanism 11 enters the outer casing 1 under cylinder drive, without close contact, serving only as a guide and blocking element. The inner casing 3 is also fed individually to the insertion station opposite the outer casing on the inner casing tube transfer frame 10. After the guide cap 14 is assembled, it is inserted into the outer casing tube 1 via the inner casing insertion drive mechanism 12. After insertion, the guide cap is automatically removed by the guide cap removal mechanism 11 described in this patent. The outer casing tube transfer frame 9 then transfers the outer casing 1 inserted into the inner casing tube to the next station, simultaneously feeding the next outer casing tube 1 to be inserted into the inner casing tube 3 to the insertion station. The inner casing tube transfer frame 10 also automatically feeds the inner casing tube. The entire process is automatically controlled by the developed control program.

[0052] In addition, the present invention also provides a method for removing the cap from the inner cladding tube of a nuclear fuel rod, comprising the following steps:

[0053] Step 1: After the outer shell tube with the ring core block is positioned on the outer shell tube transfer frame, the cylinder piston of the guide cap mechanism extends, so that the guide sleeve head extends into the outer shell tube.

[0054] Step 2: Install the guide cap on the head of the inner shell and start the developed control program to insert the inner shell tube;

[0055] Step 4: After the guide cap moves into the guide sleeve, it is hooked onto the claw hook of the guide cap clamp.

[0056] Step 5: The cylinder piston of the guide cap removal mechanism retracts, the internal top block opens the guide cap clamp, and at the same time the guide sleeve of the guide cap removal mechanism separates from the outer shell tube, and the guide cap automatically falls into the cap receiving container.

[0057] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A device for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod, characterized in that, Includes a guide cap taking mechanism (11) installed at the end of the outer shell tube transmission frame (9), the guide cap taking mechanism (11) has an advance and retreat cylinder (4), the advance and retreat cylinder (4) is connected to a guide sleeve (5), the guide sleeve (5) has an inner cavity and a guide cap gripper (6) is provided in the inner cavity to grab the guide cap (14). The guide sleeve (5) has a rectangular groove (53), and the top block (7) is fixedly installed on the outer shell tube transmission frame (9). The end of the top block (7) passes through the rectangular groove (53) of the guide sleeve (5) and can slide in the guide cap claw (6) to open the claw (63) of the guide cap claw (6). The guide cap chuck (6) is a two-lobed claw hook structure, which is made by milling grooves on a hollow ring. The width of the straight groove section (64) in the middle is greater than that of the transition section (65) at the end, so that when the straight groove section (64) in the middle of the guide cap chuck (6) moves along the top block (7), the claw hook part (62) cannot be opened, but when the transition section (65) at the end moves along the top block (7), the claw hook part (62) can be opened by the top block (7); each edge of the claw hook part (62) is blunted and smoothly transitioned, and the claw (63) is machined at the end of each lobe.

2. The device for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod according to claim 1, characterized in that, The guide sleeve (5) has a square plate structure (51) at one end for connecting the inlet and outlet cylinder (4), and a shoulder structure (52) at the other end for positioning.

3. The device for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod according to claim 2, characterized in that, The square plate structure (51) has 4 through holes for connecting the adapter plate (8).

4. The device for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod according to claim 1, characterized in that, The guide sleeve (5) has rectangular grooves (53) on both the top and bottom. The top block (7) is inserted into the middle of the guide sleeve (5) from the rectangular groove (53) on the bottom.

5. The device for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod according to claim 1, characterized in that, The inner hole of the guide sleeve (5) is composed of three sections of different diameters: a first inner hole (54), a second inner hole (55), and a third inner hole (56). The first inner hole (54) accommodates the end ring (61) of the guide cap claw (6) and performs axial positioning. The second inner hole (55) accommodates the claw hook portion (62) of the guide cap claw (6). The third inner hole (56) is used to allow the inner shell tube (3) with the guide cap (14) to pass through. The second inner hole (55) and the third inner hole (56) are transitioned by a small diameter hole section (57).

6. The device for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod according to claim 5, characterized in that, The diameter of the end ring (61) of the guide cap claw (6) is larger than the diameter of the claw hook portion (62), and the end ring (61) is axially positioned within the first inner hole (54).

7. The device for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod according to claim 1, characterized in that, The tube insertion and cap removal device also includes an inner shell tube transmission frame (10). The inner shell tube transmission frame (10) and the outer shell tube transmission frame (9) are aligned and installed on a horizontal ground. By adjusting the overall height of the frame, the single inner shell tube (3) to be inserted is made concentric with the outer shell tube (1), which facilitates the insertion of the inner shell tube (3) into the outer shell tube (1). The cap removal guide mechanism (11) is installed on the outer shell tube transmission frame (9). The guide sleeve (5) is concentric with the height of the outer shell tube (1) and is axially located on the side where the inner shell tube (3) passes through the outer shell tube (1).

8. The device for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod according to claim 1, characterized in that, The guide cap (14) includes a fitting part (58), a guide part (59) and a gripping part (60). The outer diameter of the fitting part (58) matches the inner diameter of the inner shell tube (3) and is chamfered to facilitate insertion into the inner shell tube (3). The guide part (59) is a conical transition surface, which plays a guiding and self-aligning role when inserting the tube. The gripping part (60) is a T-shaped structure with a guide at the head, and its diameter is smaller than the outer diameter of the inner shell tube (3).

9. A method for inserting and removing the cap from the inner cladding tube of a nuclear fuel rod, characterized in that, Includes the following steps: Step 1: After the outer shell tube with the ring core block is positioned on the outer shell tube transfer frame, the cylinder piston of the guide cap mechanism extends, so that the guide sleeve head extends into the outer shell tube. Step 2: Install the guide cap at the head of the inner shell and start the developed control program to insert the inner shell tube into the outer shell tube; Step 3: After the guide cap moves into the guide sleeve, it is hooked onto the guide cap clamp. Step 4: The cylinder piston of the guide cap removal mechanism retracts, and the internal top block opens the guide cap clamp, causing the guide cap to fall automatically into the cap receiving container. At the same time, the guide sleeve of the guide cap removal mechanism retracts with the cylinder piston and disengages from the outer casing tube.

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