A four-point positioning fuel assembly skeleton assembly device

Abstract

The present invention belongs to the technical field of skeleton assembly and welding, and specifically relates to a four-point positioning fuel assembly skeleton assembly device. The skeleton assembly device comprises, from right to left, a lower grid plate tube seat clamping frame, a grid A clamping frame, a grid B clamping frame, and an upper grid plate clamping frame. The above frames are all L-shaped, with a horizontal beam and a vertical beam. On the left side of the upper grid plate clamping frame, each beam is provided with a baffle extending to the inner side of the L-shape. The grid clamping frame is used to position the grid for installation and positioning. There are two grid clamping frames in the skeleton assembly device, which respectively fix grid B and grid A. The two grid clamping frames have the same structure. Each grid clamping frame needs to ensure the installation and positioning of the positioning grid of a small square structure with four sides of only 106 mm. The products produced by this device meet the high-precision requirements specified in the technology and drawings.

Description

Technical Field

[0001] The invention belongs to the technical field of skeleton assembly and welding, and in particular relates to a four-point positioning fuel assembly skeleton assembly device. Background Art

[0002] The function of the spacer grid is to fix the fuel rods in the fuel assembly at a certain position and keep the distance between the rods unchanged during the operation of the reactor. The typical spacer grid of a pressurized water reactor is a square honeycomb structure. It consists of two groups of 0.32mm thick strips that are perpendicular to each other. Each group of strips has the same number, is parallel to each other, and is arranged at equal distances. The two groups of strips are connected by a set of narrow slots ( Figure 2 The fuel rods are assembled, meshed and locked together (as shown by the number 44) to form 14×14, 15×15 or 17×17 square holes to accommodate and fix the fuel rods. The frame plates with a thickness of about 0.4 mm located on all sides accommodate and fix the ends of the strips. In the square holes of the grid, 6 contact points are provided for the fuel rods, including two elastic points and 4 rigid points. The elastic points are composed of three-bend springs punched out of the strips, and the rigid points are formed by trapezoidal protrusions punched out of the strips. In order to increase the heating rate of the fuel assembly, most of the grids are provided with mixing wings with a certain number, shape, size and different arrangements. The ideal mixing structure can increase the critical heat flux density by 10% to 20%. A certain number of guide wings are provided above and below the grid frame plate to guide when loading and unloading the fuel assembly.

[0003] The strips and frame plates are made of Inconel 718 alloy. After stamping, cleaning and nickel plating, they are assembled on a special mold, and then BNi-5 or BNi-7 brazing materials are applied to the intersection of the strips and the overlap of the frame plates, and then they are put into a vacuum molybdenum sheet furnace for brazing. After being taken out of the furnace, they are polished to become finished products. The finished grid frame needs to be inspected and adjusted for the size of the grid element; the inspection of the bending angle of the mixing wing; the inspection and correction of the direction and angle of the mixing wing; the strength measurement of the tensile test specimen brazed in the furnace; and visual review.

[0004] Modern PWR spacer grids are mostly made of nickel-based alloys. There are also zirconium alloy grids, which are characterized by a small thermal neutron absorption cross section. In between the first two are bimetallic grids, in which the strips and frame plates are zirconium alloys, and the clamping springs are still made of nickel-based alloys.

[0005] Currently, there are various types of fuel assembly skeleton manufacturing devices publicly available, including AFA3G, TVS-2M, 300MW, etc., but all of them are unable to assemble fuel assembly skeletons with poor stability. In the face of the assembly of fuel assembly skeletons with poor stability, the assembly device needs to be redesigned. Summary of the invention

[0006] The purpose of the present invention is to provide a synchronous rotation device for a nuclear fuel rod end plug ring welding machine in view of the above-mentioned defects in the prior art. The synchronous rotation requirements of the plug and the welding chuck are met, thereby improving the quality of the fuel rods. On the other hand, by designing a plug device matched with the synchronous rotation device, the centering of the tungsten electrode and the weld can be adjusted outside the welding chamber, thereby improving production efficiency.

[0007] The technical solution of the present invention is as follows:

[0008] A four-point positioning fuel assembly skeleton assembly device, the skeleton assembly device is composed of a lower grid plate tube seat clamping frame, a grid A clamping frame, a grid B clamping frame and an upper grid plate clamping frame from right to left. The above frames are all L-shaped, with a horizontal beam and a vertical beam. On the left side of the upper grid plate clamping frame, each beam is provided with a baffle extending to the inner side of the L shape. The grid clamping frame is used to position the grid for installation and positioning. There are two grid clamping frames in the skeleton assembly device, which respectively fix the grid B and the grid A. The two grid clamping frames have the same structure. Each grid clamping frame needs to ensure the installation and positioning of the positioning grid of a small square structure with a four-side size of only 106mm.

[0009] The grid clamping frame is a quadrilateral structure, and the grid clamping frame includes two pressing blocks, four positioning plates, an upper pressing frame, a side pressing frame, and a fixing frame;

[0010] The grid clamping frame base is fixed on the working platform by means of screws, fixing plates and adjusting plates, and positioning pins are used to ensure that the grid clamping frame position remains unchanged;

[0011] It is fixed in the frame and does not move. A pad is installed on two mutually perpendicular surfaces inside the fixed frame. The grooved side of the pad is the reference surface of the positioning grid.

[0012] The upper clamping frame is connected to the L-shaped fixing frame through a connecting pin, and the side clamping frame is connected to the L-shaped fixing frame through a connecting pin. The opening and closing of the upper clamping frame and the side clamping frame are realized by tightening the screw, the gasket and the rotating sleeve;

[0013] The pressing block is connected to the upper pressing frame through an anti-rotation pin to prevent the pressing block from rotating. The pressing block is connected to the screw rod through the anti-rotation pin II. The screw rod is fixed on the upper pressing frame. The screw rod is tightened to realize the pressing block pressing the grid.

[0014] The pressure block contacts the outer plate of the positioning grid in the clamped state to ensure the clamping of the positioning grid. The positioning plates are symmetrically distributed along the vertical center line. The two symmetrically distributed positioning plates on the top are of the same height, and the two symmetrically distributed positioning plates on the bottom are of the same height. The four positioning plates are distributed on the fixed frame II and the side clamping frame of the positioning grid clamping frame to ensure the four-point positioning of the grid. The positioning plates contact the lower end surface of the positioning grid to ensure that the positioning grid is perpendicular to the axis of the skeleton.

[0015] This device mainly ensures the installation and positioning of the frame, ensuring that the center distance between the two layers of positioning grids is 270mm, the upper end surface of the lower grid plate tube seat is 855mm away from the center of the first layer of positioning grids, and the upper plane of the lower grid plate tube seat is 855mm away from the lower end surface of the upper grid plate.

[0016] The fixing frame is "L" shaped.

[0017] The upper pressing plate and the side pressing plates are connected together by a rotating sleeve, so that the positioning grid can be installed and positioned. The upper pressing plate and the side pressing plates are opened to transport the skeleton.

[0018] The grid A clamping frame has the same structure as the grid B clamping frame.

[0019] The fixed frame, the upper clamping frame and the side clamping frame are connected together by connecting pins; the upper clamping frame and the side clamping frame are connected together by rotating sleeves, and the rotating sleeves are taken out. The upper clamping frame can rotate around the connecting pins at an angle, and the side clamping frame can rotate around the connecting pins at a certain angle. When the positioning frame is in an open state, the positioning grid can be placed on the pressure plate on the fixed frame, the upper clamping frame and the side clamping frame can be closed, and the tightening screws can be tightened with a torque wrench.

[0020] The beneficial effects of the present invention are:

[0021] A total of 44 sets of frames were produced using the new assembly device. The product appearance dimensions, including the distance between the upper plane of the lower grid plate tube seat and the lower plane of the upper grid plate; the distance between the centers of the two-layer positioning grids; the distance between the upper plane of the lower grid plate tube seat and the center of the first-layer positioning grid; and the parallelism indicators of the upper grid plate and the two-layer positioning grids relative to the upper plane of the lower grid plate tube seat, all meet the high-precision requirements specified in the technology and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the assembly device of the present invention;

[0023] Figure 2 Schematic diagram of the spacer grid clamping frame structure.

[0024] 101-upper grid clamping frame; 201-grid B clamping frame; 301-grid clamping A clamping frame; 401-lower grid pipe seat clamping frame; 1-fixed plate; 2-screw M10×35; 3-base; 4-screw M12×25; 5-locating pin; 6-screw M6×20; 7-locating plate; 8-pad; 9-connecting pin; 10-upper clamping frame; 11-anti-rotation pin; 12-anti-rotation pin II; 13-screw; 14-pressing block; 15-tightening screw; 16-gasket; 17-swivel sleeve; 18-fixed frame; 19-adjusting plate; 20-side clamping frame. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] A four-point positioning fuel assembly skeleton assembly device, the fuel assembly skeleton consists of 2 water rods, 2 positioning grids, 8 grid clamps, 1 lower grid plate tube seat, 1 upper grid plate, 2 spring washers and 2 hexagonal nuts. This type of skeleton has poor stability and it is not easy to ensure the skeleton assembly quality.

[0027] In order to ensure the assembly quality of the skeleton with poor stability, a four-point positioning fuel assembly skeleton assembly device is designed. The skeleton assembly device is shown in the figure. Figure 1 The device is composed of the lower grid plate pipe seat clamping frame 401, the grid A clamping frame 301, the grid B clamping frame 201 and the upper grid plate clamping frame 101 from right to left. The above frames are all L-shaped, with a horizontal beam and a vertical beam. On the left side of the upper grid plate clamping frame 101, each beam is provided with a baffle extending to the inner side of the L shape.

[0028] This device mainly ensures the installation and positioning of the frame, ensuring that the center distance between the two layers of positioning grids is 270mm, the upper end surface of the lower grid plate tube seat is 855mm away from the center of the first layer of positioning grids, and the upper plane of the lower grid plate tube seat is 855mm away from the lower end surface of the upper grid plate.

[0029] The grid clamping frame is used to install and position the grid. There are two grid clamping frames in the skeleton assembly device, which fix grid B and grid A respectively. The two grid clamping frames have the same structure. Each grid clamping frame needs to ensure the installation and positioning of the positioning grid with a small square structure with a four-side size of only 106mm.

[0030] The grid clamping frame is a quadrilateral structure, and is mainly composed of two pressing blocks 14, four positioning plates 7, an upper pressing frame 10, a side pressing frame 20, a fixing frame 18 and other components.

[0031] The grid clamping frame base 3 is installed and fixed on the working platform by means of the screw rod 2, the fixing plate 1 and the adjusting plate 19, and the positioning pin 5 is used to ensure that the position of the grid clamping frame remains unchanged.

[0032] The fixing frame 18 is "L"-shaped and is fixed in the frame. A cushion block 8 is respectively installed on two mutually perpendicular surfaces inside the fixing frame 18, and a grooved surface of the cushion block is a reference surface for positioning the grid.

[0033] The upper clamping frame 10 is connected to the "L"-shaped fixing frame through the connecting pin 9, and the side clamping frame 20 is connected to the "L"-shaped fixing frame through the connecting pin 9. The opening and closing of the upper clamping frame 10 and the side clamping frame 20 are achieved by tightening the screw 15, the gasket 16 and the rotating sleeve 17.

[0034] The pressing block 14 is connected to the upper pressing frame 10 through the anti-rotation pin 11 to prevent the pressing block from rotating. The pressing block 14 is connected to the screw 13 through the anti-rotation pin II12. The screw 13 is fixed on the upper pressing frame 10. The screw 10 is tightened to achieve the pressing block 14 to press the grid. The pressing block 14 is connected to the side pressing frame 20 through the anti-rotation pin 11 to prevent the pressing block from rotating. The pressing block 14 is connected to the screw 13 through the anti-rotation pin II12. The screw 13 is fixed on the side pressing frame 20. The screw 10 is tightened to achieve the pressing block 14 to press the grid.

[0035] The pressure block contacts the outer plate of the positioning grid in the clamped state to ensure the clamping of the positioning grid. The positioning plates 7 are symmetrically distributed along the vertical center line. The two positioning plates 7 symmetrically distributed above are of the same height, and the two positioning plates 7 symmetrically distributed below are of the same height. The four positioning plates are distributed on the fixed frame II and the side clamping frame of the positioning grid clamping frame to ensure the four-point positioning of the grid. The positioning plate contacts the lower end surface of the positioning grid to ensure that the positioning grid is perpendicular to the axis of the skeleton. The upper pressure plate and the side pressure plate are connected together by a rotary sleeve to install and position the positioning grid. The upper pressure plate and the side pressure plate are opened to transport the skeleton.

[0036] The fixing frame 18, the upper pressing frame 10 and the side pressing frame 20 are connected together by the connecting pin 9. The upper pressing frame and the side pressing frame are connected together by the rotating sleeve 17. The rotating sleeve is removed, and the upper pressing frame 10 can rotate around the connecting pin 19 at a certain angle, and the side pressing frame can rotate around the connecting pin at a certain angle at the same time. When the positioning frame is in an open state, the positioning grid can be placed on the pressure plate on the fixing frame, the upper pressing frame 10 and the side pressing frame 20 are closed, and the tightening screws are tightened with a torque wrench.

Claims

1. A four-point positioning fuel assembly skeleton assembly device, the skeleton assembly device comprises, from right to left, a lower grid plate tube seat clamping frame, a grid A clamping frame, a grid B clamping frame and an upper grid plate clamping frame, all of the above frames are L-shaped, with a horizontal beam and a vertical beam, and on the left side of the upper grid plate clamping frame, each beam is provided with a baffle extending to the inner side of the L-shape, characterized in that: The grid clamping frame is used for the installation and positioning of the positioning grid. There are two grid clamping frames in the skeleton assembly device, which fix the grid B and the grid A respectively. The two grid clamping frames have the same structure. Each grid clamping frame needs to ensure the installation and positioning of the positioning grid of a small square structure with a four-side size of only 106mm. The grid clamping frame includes two pressing blocks, four positioning plates, an upper pressing frame, a side pressing frame, and a fixing frame; The grid clamping frame base is fixed on the working platform by means of screws, fixing plates and adjusting plates, and positioning pins are used to ensure that the grid clamping frame position remains unchanged; It is fixed in the frame and does not move. A pad is installed on two mutually perpendicular surfaces inside the fixed frame. The grooved side of the pad is the reference surface of the positioning grid. The upper clamping frame is connected to the L-shaped fixing frame through a connecting pin, and the side clamping frame is connected to the L-shaped fixing frame through a connecting pin. The opening and closing of the upper clamping frame and the side clamping frame are realized by tightening the screw, the gasket and the rotating sleeve; The pressing block is connected to the upper pressing frame through an anti-rotation pin to prevent the pressing block from rotating. The pressing block is connected to the screw rod through the anti-rotation pin II. The screw rod is fixed on the upper pressing frame. The screw rod is tightened to realize the pressing block pressing the grid. The pressure block contacts the outer plate of the positioning grid in the clamped state to ensure the clamping of the positioning grid. The positioning plates are symmetrically distributed along the vertical center line. The two symmetrically distributed positioning plates on the top are of the same height, and the two symmetrically distributed positioning plates on the bottom are of the same height. The four positioning plates are distributed on the fixed frame II and the side clamping frame of the positioning grid clamping frame to ensure the four-point positioning of the grid. The positioning plates contact the lower end surface of the positioning grid to ensure that the positioning grid is perpendicular to the axis of the skeleton.

2. A four-point positioning fuel assembly skeleton assembly device as claimed in claim 1, characterized in that: This device mainly ensures the installation and positioning of the frame, ensuring that the center distance between the two layers of positioning grids is 270mm, the upper end surface of the lower grid plate tube seat is 855mm away from the center of the first layer of positioning grids, and the upper plane of the lower grid plate tube seat is 855mm away from the lower end surface of the upper grid plate.

3. A four-point positioning fuel assembly skeleton assembly device as claimed in claim 1, characterized in that: The fixing frame is "L" shaped.

4. A four-point positioning fuel assembly skeleton assembly device as claimed in claim 1, characterized in that: The upper pressing plate and the side pressing plates are connected together by a rotating sleeve, and the positioning grid can be installed and positioned. The upper pressing plate and the side pressing plates are opened to transport the skeleton.

5. A four-point positioning fuel assembly skeleton assembly device as claimed in claim 1, characterized in that: The fixed frame, the upper clamping frame and the side clamping frame are connected together by connecting pins; the upper clamping frame and the side clamping frame are connected together by rotating sleeves, and the rotating sleeves are taken out. The upper clamping frame can rotate around the connecting pins at an angle, and the side clamping frame can rotate around the connecting pins at a certain angle. When the positioning frame is in an open state, the positioning grid can be placed on the pressure plate on the fixed frame, the upper clamping frame and the side clamping frame can be closed, and the tightening screws can be tightened with a torque wrench.

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