Location grid with long direction eddy generator

[0030] Refer to figure 1 (a) and figure 1 As shown in (b), the fuel assembly 10 is composed of a lower structure or lower tube holder 12, a control rod guide tube 14, a positioning grid 16, a fuel rod 18, a representative tube 20, and an upper structure or upper tube holder 22. The lower tube holder 12 is used to support the components seated on the lower core plate (not shown) of the core (not shown); the control rod guide tube 14 extends upward from the lower tube holder 12; the horizontal positioning grid The rack 16 is used to provide lateral support for the fuel rods arranged in a certain manner, and the upper tube base 22 is connected to the upper end of the guide tube 14 to form a complete assembly that can perform conventional operations without damaging the fuel assembly components. Both the lower tube socket 12 and the upper tube socket 22 have a connecting plate, and a hole on the plate allows liquid coolant (for example, water) to flow therethrough. A set of rod bundle control components 28 are in place in the box defined by the enclosure plate of the upper tube base 22. As is well known, in order to make the control rod 32 move vertically in the control rod guide tube 14, the rod bundle control assembly 28 is provided with an anchor hook 30 arranged radially extending and connected to the top end of the control rod 32. When assembling the fuel assembly 10, the positioning grid 16 and the guide sleeve 14 are connected at a predetermined axial position, the fuel rods 18 are inserted in place through respective grid elements formed by the interconnected strips, and the lower tube holder 12 fits It is connected with the lower end of the guide sleeve 14, and the upper tube base 22 is connected with the upper end of the guide sleeve 14. A more detailed description of the general parts of the fuel assembly 10 can be found in US Patent 4,061,536. Conventional positioning grids, for example, the positioning grids shown and described in U.S. Patent Nos. 3,379,619 and 4,061,536, are made of strips that are mated with each other into an egg basket to provide a grid for receiving fuel rods. Each grid element supports the fuel rod by means of springs and rigid protrusions, and the springs and rigid protrusions of each grid element are generally frictionally engaged with the fuel rod at 6 points. Also, it is well known that in order to promote the mixing of coolant fluids, the positioning grid may include mixing wings.

[0031] See figure 2 (a) and figure 2 As shown in (b), the positioning grid 16 is formed by interweaving inner strips 24 to form a grid element 34 through which the corresponding fuel rod 18 extends. The positioning grid 16 also includes an outer strip 36. The outer strip 36 is connected by lap joints at its ends so as to surround the cell structure formed by the inner strip 24. At the same time, the end of the inner strip 24 should be connected to the outer strip 36. connection. As by figure 2 (a) and figure 2 (b) As you can see, each outer strip 36 or inner strip 24 consists of a main body 40 and two upper and lower sets of first triangular longitudinal vortex generators 42 that open in different directions (in the same cell). And the second triangular longitudinal vortex generator 44 or the first rectangular longitudinal vortex generator 43 and the second rectangular longitudinal vortex generator 45. The first triangular longitudinal vortex generator 42 and the second triangular longitudinal vortex generator 44 or the first rectangular longitudinal vortex generator 43 and the second rectangular longitudinal vortex generator 45 are not installed, but on the outer strip 36 and the inner strip. The belt 24 is formed by stamping and folding. The advantage of this is that it greatly simplifies the manufacturing process of the positioning grid and reduces the manufacturing cost of the grid. In addition, due to the small volume of the triangular (rectangular) longitudinal vortex generator, the resistance of the grid to the coolant flowing through is greatly reduced. At the same time, the vortex generator can also mix the fluid, causing the fluid to produce longitudinal vortex, thereby enhancing the heat exchange capacity.

[0032] See image 3 (a) and image 3 (b), Figure 4 (a) and Figure 4 (b), Figure 5 , Figure 6 As shown, the triangular (or rectangular) longitudinal vortex generator in the positioning grid of the present invention will be described in detail. As pointed out above, the first triangular longitudinal vortex generator 42 and the second triangular longitudinal vortex generator 44 or the first rectangular longitudinal vortex generator 43 and the second rectangular longitudinal vortex generator 45 of the present invention are respectively inner strips 24 and As an integral part of the outer strip 36, each triangular (or rectangular) longitudinal vortex generator is punched out by punching a narrow groove along the longitudinal edge of the vortex generator with the corresponding inner strip 24 and outer strip 36.

[0033] The triangular longitudinal vortex generators are arranged vertically on the inner strip 24 and the outer strip 36. Each cell channel such as 34 contains 2 sets of 4 pairs of 8 triangular longitudinal vortex generators. These two sets of longitudinal vortex generators are parallel to each other. It does not appear on the same strip, but on the four walls of each cell. Among them, the two pairs of triangular longitudinal vortex generators appearing on the two adjacent walls of the upper part of the cell are the first triangular longitudinal vortex generators 42, and the two pairs of triangular longitudinal vortex generators appearing on the lower part of the other two adjacent walls are the first. Two triangular longitudinal vortex generators 44, respectively called the first triangular longitudinal vortex generator 42 and the second triangular longitudinal vortex generator 44 (see figure 2 ), the first triangular longitudinal vortex generator 42 and the second triangular longitudinal vortex generator 44 are symmetrically arranged in each cell channel to simplify processing and make the fuel rod 18 evenly stressed. The first triangular longitudinal vortex generator 42 It cooperates with the second triangular longitudinal vortex generator 44 to clamp the fuel rod 18 up and down to complete the lateral holding function.

[0034] The first rectangular longitudinal vortex generator 43 and the second rectangular longitudinal vortex generator 45 are vertically arranged on the inner strip 24 and the outer strip 36, and each cell channel (such as 34) contains 2 groups, 2 pairs, and 4 in total. The rectangular vortex generator is arranged symmetrically in each cell channel to simplify processing and make the fuel rod 18 evenly stressed. The first rectangular longitudinal vortex generator 43 and the second rectangular longitudinal vortex generator 45 are not on the same strip, but are distributed on the four walls of each cell, and each wall contains a vortex generator. . Among them, the first rectangular longitudinal vortex generator 43 is located next to two adjacent wall surfaces on the upper part; the second rectangular longitudinal vortex generator 45 is located at the lower part.

[0035] The angle α between the first triangular longitudinal vortex generator 42 (42a, 42b, 42c, 42d) and the second triangular longitudinal vortex generator 44 (44a, 44b, 44c, 44d) and the main flow direction is between 15°-60°, Among them, the effect is best at 30°, and the length of its adjacent vertical short side is half of the long side, that is, W/H is equal to 0.5, such as Figure 5 Shown.

[0036] The angle α between the first rectangular longitudinal vortex generator 43 (43a, 43b) and the second rectangular longitudinal vortex generator 45 (45a, 45b) and the main flow direction is between 15° and 75°, where the included angle of 45° is optimal. The aspect ratio is about 2:1, that is, C/B≈2:1, and the rectangular center of the first rectangular longitudinal vortex generator 43 is 1/11 away from the top of the positioning grid, that is, H/HC=1/11; Similarly, the rectangular center of the second rectangular longitudinal vortex generator 45 is 1/11 from the bottom of the positioning grid. The sheet bend angle β of the first rectangular longitudinal vortex generator 43 and the second rectangular longitudinal vortex generator 45 is 90°, that is, the sheet bends are cut perpendicular to the strip.