Multi-layer structure lower tube base supporting structure, lower tube base and nuclear fuel assembly

Abstract

The invention relates to the technical field of nuclear fuel assemblies, in particular to a multi-layer structure lower tube base supporting structure, a lower tube base and a nuclear fuel assembly.The multi-layer structure lower tube base supporting structure comprises a dot matrix supporting mechanism, and the dot matrix supporting mechanism comprises a dot matrix connecting layer and hollow grids; the dot matrix connecting layer comprises at least two dot matrix monomers which are connected with each other, the at least two dot matrix monomers are arranged in parallel, and the end parts of the at least two dot matrix monomers are flush with each other; the lattice monomers are of a polyhedral hollowed-out structure, the two ends of each lattice monomer are connected with the corresponding hollowed-out grids, and therefore the requirement for supporting strength can be met, and meanwhile circulation of a cooling medium is facilitated. The lower pipe seat comprises a lower pipe seat body, a pipe barrel and the multi-layer lower pipe seat supporting structure. The nuclear fuel assembly comprises a plurality of fuel elements, a connecting assembly, an upper tube base, a control rod guide tube and a positioning grillwork, and further comprises the multi-layer structure lower tube base supporting structure or the nuclear fuel assembly lower tube base.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear fuel assemblies, and in particular to a multi-layer structured lower tube seat support structure, a lower tube seat and a nuclear fuel assembly. Background Art

[0002] A nuclear fuel assembly refers to a whole group of fuel elements assembled together. It consists of several fuel elements, connection components, upper tube seats, lower tube seats, control rod guide tubes, and positioning grids. Among them, the lower tube seat is located at the bottom of the nuclear fuel assembly and is responsible for bearing the load of the entire nuclear fuel assembly. There are certain requirements for the support strength of the lower tube seat itself. Summary of the invention

[0003] The present invention provides a multi-layer structure lower tube seat support structure, a lower tube seat and a nuclear fuel assembly, which can meet the support strength requirements and facilitate the circulation of cooling medium to dissipate and cool the heat emitted by the upper fuel rods.

[0004] The present invention is achieved through the following technical solutions:

[0005] In the first aspect, the present invention provides a multi-layer structure lower tube seat support structure, including a lattice support mechanism, the lattice support mechanism includes a lattice connection layer and a hollow grid; the lattice connection layer includes at least two connected lattice monomers, at least two of the lattice monomers are arranged in parallel, and the ends of at least two of the lattice monomers are flush; the lattice monomers are polyhedral hollow structures, and both ends of the lattice monomers are connected to the corresponding hollow grids.

[0006] The existing nuclear fuel assembly consists of several fuel elements, connection components, upper tube seats, lower tube seats, control rod guide tubes and positioning grids. The lower tube seat is located at the bottom of the nuclear fuel assembly. The upper part of the lower tube seat needs to be connected to multiple guide tubes and instrument tubes, and fuel rods are placed. The fuel rods will emit a lot of heat during the operation process. The lower tube seat is responsible for the load of the entire fuel assembly. There are certain requirements for the support strength and mechanical properties of the lower tube seat itself. It is also required that the lower tube seat has a certain cooling medium conduction function to facilitate the heat dissipation and cooling of the heat emitted by the upper fuel rods.

[0007] In this regard, the multi-layer structure lower tube seat support structure provided by the present invention includes a lattice support mechanism, the lattice support mechanism includes a lattice connection layer and a hollow grid, the lattice connection layer includes at least two connected lattice monomers, at least two lattice monomers are arranged in parallel, the ends of at least two lattice monomers are flush, the lattice monomers are polyhedral hollow structures, and both ends of the lattice monomers are connected to the corresponding hollow grids. Thus, the normal circulation of the cooling medium is ensured by the hollow structure, and the lattice monomers are arranged in parallel and the ends are flush, and the hollow grids are connected to the two ends of the lattice monomers, which facilitates the connection of the end faces of the lattice support mechanism with the remaining components, so as to have good tensile and compressive properties and meet the strength requirements. Compared with the traditional solid lower tube seat, this patent can use less material to achieve structural compressive performance that meets the strength requirements.

[0008] Among them, by setting up a multi-layer hollow structure, there are multiple gaps to facilitate the flow of the cooling medium, and by setting up a hollow grid and a plurality of lattice monomers placed in parallel, it can play a diversion role on the cooling medium flowing through, ensure the uniformity of the flow rate, and also play a certain interception role on impurities and foreign matter in the cooling medium. In the present invention, the lattice monomers are arranged in parallel and the ends are flush, the hollow grid is connected to the two ends of the lattice monomers, and the structure of each layer of the lattice connection layer is the same, and the ends of the lattice monomers of the adjacent two layers are arranged oppositely, so that the wall area of ​​the flow channel formed by the lattice structure is smaller than that of the solid flow channel lower tube seat, and there are no staggered lattice ribs, so the resistance along the coolant flow channel of the present invention is less than that of the traditional solid flow channel lower tube seat, and at the same time, because the material used is less than the solid flow channel lower tube seat, there is more space for the coolant to circulate inside, and the local resistance is less than the multi-layer staggered lattice lower tube seat of the existing patent (publication number: CN115206558), and the present invention is more conducive to the circulation of the coolant. In summary, the multi-layer lower tube seat support structure provided by the present invention can meet the support strength requirements while facilitating the circulation of cooling medium to dissipate and cool the heat emitted by the upper fuel rods, and can also play a certain role in intercepting impurities and foreign matter in the cooling medium.

[0009] In an optional embodiment of the present application, the lattice monomer includes a plurality of upper prisms and a plurality of lower prisms, the upper prisms and the lower prisms are arranged in one-to-one correspondence, the top ends of the plurality of upper prisms are connected to each other, and the top ends of the upper prisms are connected to the hollow grid, the bottom ends of the upper prisms are respectively connected to the top ends of the corresponding lower prisms to form a first reinforcement portion, the bottom ends of the plurality of lower prisms are connected to each other, and the bottom ends of the lower prisms are connected to the corresponding hollow grid, and a prism cavity is formed between the upper prisms and the lower prisms, wherein the top ends of the upper prisms in different lattice monomers are flush, and the bottom ends of the lower prisms in different lattice monomers are flush, so that the lattice monomer presents a polyhedral hollow structure.

[0010] In an optional embodiment of the present application, the lattice monomer also includes a transverse column, which is located in the prism cavity. The two ends of the transverse column are respectively connected to the corresponding first reinforcement parts. On the one hand, it can strengthen the prism structure of the lattice monomer, and the transverse column can block debris. The transverse column divides the prism cavity into a plurality of medium flow channels. The effective cross-sectional area of ​​each medium flow channel is small, which is conducive to the interception and filtration of foreign matter and impurities, thereby filtering the cooling medium. On the other hand, it can divert the cooling medium passing through the prism cavity.

[0011] In an optional embodiment of the present application, the hollow grid includes multiple layers of grid plates, and different schemes can be designed between the multiple grid plates according to the actual coolant flow and resistance conditions, such as aligned arrangement to reduce flow resistance, or staggered arrangement to increase the diversion effect of the coolant.

[0012] In an optional embodiment of the present application, a second reinforcement portion is formed at the connection between the plurality of grid plates, and the second reinforcement portion is connected to both ends of the lattice monomer. The connection with the lattice monomer through the second reinforcement portion helps to increase the connection strength between the hollow grid and the lattice monomer and improve the tensile and compressive properties of the lattice monomer.

[0013] In the second aspect, the present invention provides a lower tube seat of a nuclear fuel assembly, comprising a lower tube seat body, a tube and the above-mentioned multi-layer lower tube seat support structure, the tube is embedded in the lattice connection layer, and the extension direction of the tube is consistent with the arrangement direction of the lattice connection layer, and the tube passes through the hollow grid.

[0014] The lower tube seat of a nuclear fuel assembly provided by the present invention comprises a lattice support mechanism and a tube embedded in a lattice connection layer. The extension direction of the tube is consistent with the arrangement direction of the lattice connection layer, and the tube passes through a hollow grid. The cavity in the tube is used to connect and position a guide tube and an instrument tube. The lattice connection layer and the hollow grid are used to position the tube, so that the lower tube seat has a certain support strength, can conduct a cooling medium, and is convenient for connecting the guide tube and the instrument tube.

[0015] In an optional embodiment of the present application, the lower tube seat body also includes a frame, which is arranged outside the lattice connection layer. By setting the frame, it is used to limit the outer edge of the lattice connection layer, and can also increase the compressive resistance of the lattice connection layer to prevent the lattice monomer from being deformed under pressure.

[0016] In an optional embodiment of the present application, the top surface of the frame is flush with the top surface of the topmost hollow grid, which helps to connect the remaining components above the lower tube seat.

[0017] In an optional embodiment of the present application, the frame is provided with supporting feet, and the supporting feet are provided with pin holes so as to play a supporting role through the supporting feet, and the provision of the pin holes helps to improve the positioning accuracy of the lower tube seat and the lower component.

[0018] In a third aspect, the present invention provides a nuclear fuel assembly, comprising a plurality of fuel elements, a connection assembly, an upper tube seat, a control rod guide tube and a positioning grid, and also comprising the above-mentioned multi-layer structure lower tube seat support structure or the above-mentioned nuclear fuel assembly lower tube seat.

[0019] That is to say, the nuclear fuel assembly provided by the present invention includes a plurality of fuel elements, a connection assembly, an upper tube seat, a control rod guide tube and a positioning grid, the above-mentioned multi-layer structure lower tube seat support structure or the above-mentioned nuclear fuel assembly lower tube seat, which can ensure that it has sufficient strength and facilitates the uniform circulation of the cooling medium.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] 1. The multi-layer lower tube seat support structure provided by the present invention includes a lattice support mechanism, which includes a lattice connection layer and a hollow grid. The lattice connection layer includes at least two connected lattice monomers, at least two lattice monomers are arranged in parallel, and the ends of at least two lattice monomers are flush. The lattice monomers are polyhedral hollow structures, and both ends of the lattice monomers are connected to the corresponding hollow grids. Therefore, the normal circulation of the cooling medium is ensured by the hollow structure, and the lattice monomers are arranged in parallel and the ends are flush. The hollow grids are connected to the two ends of the lattice monomers, which facilitates the connection of the end faces of the lattice support mechanism with the remaining components, so that it has good tensile and compressive properties and meets the strength requirements.

[0022] 2. The multi-layer lower tube seat support structure provided by the present invention is provided with a multi-layer hollow structure. The lattice monomers are arranged in parallel and the ends are flush. The hollow grids are connected to the two ends of the lattice monomers, and the structures of the lattice connection layers of each layer are the same. The ends of the lattice monomers of two adjacent layers are arranged facing each other, which further reduces the along-the-way resistance and local resistance during the circulation of the coolant and facilitates the circulation of the coolant.

[0023] 3. The multi-layer lower tube seat support structure provided by the present invention is provided with a hollow grid and a plurality of lattice monomers placed in parallel, which can divert the cooling medium flowing through, ensure the uniformity of the flow rate, and also have a certain interception effect on impurities and foreign matter in the cooling medium.

[0024] 4. The lower tube seat provided by the present invention includes a lattice support mechanism and a tube embedded in the lattice connection layer. The extension direction of the tube is consistent with the arrangement direction of the lattice connection layer, and the tube passes through the hollow grid. The cavity in the tube is used to connect and position the guide tube and the instrument tube. The lattice connection layer and the hollow grid play a positioning role for the tube, so that the lower tube seat has a certain supporting strength, can conduct cooling medium, and is convenient for connecting the guide tube and the instrument tube.

[0025] 5. The nuclear fuel assembly provided by the present invention includes a plurality of fuel elements, a connection assembly, an upper tube seat, a control rod guide tube and a positioning grid, and also includes the above-mentioned multi-layer structure lower tube seat support structure or the above-mentioned nuclear fuel assembly lower tube seat, which can ensure that it has sufficient strength and facilitates the uniform circulation of the cooling medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can also be obtained based on these drawings without creative work.

[0027] In the attached picture:

[0028] Figure 1 It is a structural schematic diagram of a lattice support mechanism provided in an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of the structure of a lattice monomer provided in an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of the structure of a hollow grid provided in an embodiment of the present invention;

[0031] Figure 4 Another schematic diagram of the structure of a lattice monomer provided in an embodiment of the present invention;

[0032] Figure 5 It is a schematic diagram of the top surface structure of the lower tube seat provided in an embodiment of the present invention;

[0033] Figure 6 It is a schematic diagram of the bottom surface structure of the lower tube seat provided in an embodiment of the present invention.

[0034] Reference numerals and corresponding component names in the accompanying drawings:

[0035] 10-lower tube seat body; 100-lattice support mechanism; 110-lattice connection layer; 111-lattice monomer; 111a-upper prism; 111b-lower prism; 111c-first reinforcement part; 111d-cross column; 112-prism cavity; 120-hollow grid; 121-grid plate; 122-grid hole; 123-second reinforcement part; 200-tube; 300-frame; 310-support foot; 311-pin hole. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0038] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0039] In the description of the embodiments of the present application, the indicated orientation or position relationship is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is conventionally placed when in use, or is the orientation or position relationship conventionally understood by those skilled in the art. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0040] In the description of this application, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0042] It should be noted that a nuclear fuel assembly refers to a whole group of fuel elements assembled together, which consists of several fuel elements, connection components, upper tube seats, lower tube seats, control rod guide tubes, and positioning grids. The lower tube seat is located at the bottom of the nuclear fuel assembly. The upper part of the lower tube seat needs to be connected to multiple guide tubes and instrument tubes, and fuel rods are placed. The fuel rods will emit a lot of heat during the operation process. The lower tube seat is responsible for the load of the entire fuel assembly. There are certain requirements for the support strength and mechanical properties of the lower tube seat itself. It is also required that the lower tube seat has a certain cooling medium conduction function to facilitate the heat dissipation and cooling of the heat emitted by the upper fuel rods.

[0043] In this regard, the inventor innovatively designed the following technical solution, and the specific implementation solution of this application will be described in detail below with reference to the accompanying drawings.

[0044] Example 1

[0045] Combination Figure 1 The present embodiment provides a multi-layer structure lower tube seat support structure, including a lattice support mechanism 100, the lattice support mechanism 100 includes a lattice connection layer 110 and a hollow grid 120; the lattice connection layer 110 includes at least two connected lattice monomers 111, at least two of the lattice monomers 111 are arranged in parallel, and the ends of at least two of the lattice monomers 111 are flush; the lattice monomers 111 are polyhedral hollow structures, and both ends of the lattice monomers 111 are connected to the corresponding hollow grids 120.

[0046] Specifically, the lattice support mechanism 100 provided in this embodiment includes a lattice connection layer 110 and a hollow grid 120; the number of the lattice connection layers 110 is three, and both ends of each lattice connection layer 110 are connected to a hollow grid 120, and adjacent lattice connection layers 110 are connected to a hollow grid 120. The lattice connection layer 110 includes at least two lattice monomers 111, which are hollow structures, are arranged in parallel and have flush ends, and the hollow grid 120 is connected to both ends of the lattice monomer 111.

[0047] It is understandable that the structure of the lattice monomer 111 is not unique. The structure of the lattice monomer 111 in the first lattice connection layer 110 is consistent with the structure of the lattice monomer 111 in the third lattice connection layer 110, and both are different from the structure of the lattice monomer 111 in the second lattice connection layer 110. Similarly, the structure of the lattice monomer 111 in the same lattice connection layer 110 can be different according to actual use requirements. In practical applications, the number of lattice connection layers 110 can also be one, two, four, etc.

[0048] The specific structure of the lattice monomer 111 is usually a polyhedron, such as a hexagonal prism, an octagonal prism, a dodecahedron, etc. In the present embodiment, the lattice monomer 111 is an octagonal structure, and the lattice monomer 111 is a vertically symmetrical structure.

[0049] Combination Figure 2 In this embodiment, the lattice monomer 111 includes a plurality of upper prisms 111a and a plurality of lower prisms 111b. The top ends of the plurality of upper prisms 111a are connected to each other, and there are gaps between the bottom ends of the plurality of upper prisms 111a, so that the plurality of upper prisms 111a form a divergent structure that is small at the top and large at the bottom. The bottom ends of the plurality of lower prisms 111b are connected to each other, and there are gaps between the bottom ends of the plurality of lower prisms 111b, so that the plurality of lower prisms 111b form a divergent structure that is small at the bottom and large at the top. In addition, the bottom end of the upper prism 111a is connected to the top end of the lower prism 111b, and one upper prism 111a is connected to one lower prism 111b. At the same time, a first reinforcing portion 111c is formed at the connection between the two, so that a prism cavity 112 is formed between the upper prism 111a and the lower prism 111b. That is, the cooling medium can flow through the prism cavity 112 , and each prism in each lattice monomer 111 can play a certain role in diverting the cooling medium, thereby ensuring the flow uniformity of the cooling medium.

[0050] Since the number of lattice monomers 111 is at least two, and the top ends of the upper prisms 111a in different lattice monomers 111 are flush, and the bottom ends of the lower prisms 111b in different lattice monomers 111 are flush, the lattice monomers 111 formed by each prism structure enable the lattice connection layer 110 and the lattice support mechanism 100 to have good strength and tensile and compressive properties.

[0051] In addition, the adjacently arranged lattice monomers 111 may be connected to each other through the first reinforcing portion 111 c , thereby increasing the connection stability between the lattice monomers 111 in the same lattice connection layer 110 .

[0052] Recombination Figure 2, the dot matrix monomer 111 further includes a cross column 111d. The end of the cross column 111d is connected to the first reinforcing portion 111c. The cross column 111d is in a cross shape and is located in the edge cavity 112, which is used to increase the self-strength and connection stability of the dot matrix monomer 111, and improve the tensile and compressive properties of the dot matrix monomer 111. It can be understood that the cross column 111d located in the edge cavity 112 can also play a certain role in intercepting and filtering foreign impurities in the flowing cooling medium.

[0053] Combined with Figure 3 , the cross column 111d can be located at the edge of the edge cavity 112 and is used to connect two adjacent first reinforcing portions 111c. The cross column 111d located at the edge of the edge cavity 112 can also increase the self-strength and connection stability of the dot matrix monomer 111, improve the tensile and compressive properties of the dot matrix monomer 111, and can also play a certain role in intercepting and filtering foreign impurities in the flowing cooling medium.

[0054] Combined with Figure 4 , the hollow grid 120 includes a plurality of grid plates 121, and the grid plates 121 are arranged staggeredly, so that the hollow grid 120 presents a structure of multiple superimposed "field" characters. Grid holes 122 are formed between the plurality of grid plates 121. By setting the grid holes 122, it is convenient for the cooling medium to pass through, avoiding the hindrance to the flow of the cooling medium, and also playing a certain role in dividing the flow of the cooling medium.

[0055] A second reinforcing portion 123 is formed at the connection of the grid plates 121. The second reinforcing portion 123 is connected to the top end of the upper prism 111a or the bottom end of the lower prism 111b, so that the hollow grid 120 is tightly connected to both ends of the dot matrix connection layer 110, increasing the structural strength of both ends of each dot matrix monomer 111. In addition, the second reinforcing portion 123 can also play a role in limiting both ends of the dot matrix monomer 111, enabling the dot matrix monomer 111 to have better tensile and compressive properties.

[0056] In summary, the multi-layer structure lower pipe seat support structure provided in this embodiment includes a dot matrix support mechanism 100. The dot matrix support mechanism 100 includes a dot matrix connection layer 110 and a hollow grid 120. The dot matrix connection layer 110 includes at least two connected dot matrix monomers 111. At least two dot matrix monomers 111 are arranged in parallel, and the ends of at least two dot matrix monomers 111 are flush. The dot matrix monomer 111 has a polyhedral hollow structure, and both ends of the dot matrix monomer 111 are connected to the corresponding hollow grid 120. Its working principle is as follows:

[0057] The multi-layer structure of the lower pipe seat support structure includes a lattice connection layer 110 and a hollow grid 120. The lattice connection layer 110 includes at least two lattice monomers 111 in a polyhedral hollow structure, and the hollow structure ensures the normal circulation of the cooling medium. The lattice monomers 111 are arranged in parallel and the ends are flush. The hollow grid 120 is connected to the two ends of the lattice monomers 111, which facilitates the connection of the end face of the lattice support mechanism 100 with the other components, so as to have good tensile and compressive resistance and meet the strength requirements.

[0058] Therefore, it can be seen that the multi-layer lower tube seat support structure provided in this embodiment has at least the following advantages:

[0059] (1) By setting up a prismatic structure, the strength requirements are met while having good tensile and compressive properties;

[0060] (2) By providing a multi-layer hollow structure, there are multiple gaps to facilitate the flow of cooling medium;

[0061] (3) The arrangement of the prisms and the crossbar 111d facilitates the interception of impurities and foreign matter in the cooling medium, thereby preventing them from contacting the fuel rods above and causing scratches on the fuel rods;

[0062] (4) By providing the hollow grid 120 and the plurality of lattice monomers 111 placed in parallel, the cooling medium flowing through can be diverted to ensure the uniformity of the flow rate.

[0063] In addition, it should be noted that the flow channel of the conventional lower tube seat is a long flow channel with large resistance along the way, and the staggered local resistance of the lattice of the multi-layer staggered tube seat is large. In this embodiment, the lattice monomers are arranged in parallel and the ends are flush, the hollow grids are connected to the two ends of the lattice monomers, and the structure of each layer of the lattice connection layer is the same ( Figure 1 ), the ends of the two adjacent layers of lattice monomers are arranged opposite to each other, so that the wall area of ​​the flow channel formed by the lattice structure is smaller than the lower tube seat of the solid flow channel, and there are no staggered lattice ribs, so that the flow channel resistance and local resistance formed by the lattice monomers are significantly reduced, which is more conducive to the circulation of coolant and ensures the structural strength.

[0064] Example 2

[0065] Combination Figure 5 The present embodiment provides a lower tube seat of a nuclear fuel assembly, comprising a lower tube seat body 10, a tube tube 200 and the multi-layer lower tube seat support structure described in Example 1, wherein the tube tube 200 is embedded in the lattice connection layer 110, and the extension direction of the tube tube 200 is consistent with the arrangement direction of the lattice connection layer 110, and the tube tube 200 passes through the hollow grid 120.

[0066] It can be understood that the socket support structure under the multi-layer structure includes a lattice support mechanism 100, and the lattice support mechanism 100 includes a lattice connection layer 110 and a hollow grid 120; the lattice connection layer 110 includes at least two connected lattice monomers 111, at least two of the lattice monomers 111 are arranged in parallel, and the ends of at least two of the lattice monomers 111 are flush; the lattice monomer 111 has a polyhedral hollow structure, and both ends of the lattice monomer 111 are connected to the corresponding hollow grid 120.

[0067] Among them, the lattice monomer 111 includes a plurality of upper prisms 111a and a plurality of lower prisms 111b. The tops of the plurality of upper prisms 111a are connected to each other, and there are gaps between the bottoms of the plurality of upper prisms 111a, so that the plurality of upper prisms 111a form a divergent structure with a smaller top and a larger bottom. The bottoms of the plurality of lower prisms 111b are connected to each other, and there are gaps between the bottoms of the plurality of lower prisms 111b, so that the plurality of lower prisms 111b form a divergent structure with a smaller bottom and a larger top. Moreover, the bottom end of the upper prism 111a is connected to the top end of the lower prism 111b, one upper prism 111a is correspondingly connected to one lower prism 111b, and at the same time, a first strengthening part 111c is formed at the connection part therebetween, so that a rib cavity 112 is formed between the upper prism 111a and the lower prism 111b. That is, the cooling medium can flow through the rib cavity 112, and each prism in each lattice monomer 111 can play a certain role in diverting the cooling medium, thereby ensuring the flow uniformity of the cooling medium.

[0068] At the same time, the lattice monomer 111 further includes a cross column 111d. The end of the cross column 111d is connected to the first strengthening part 111c, and the cross column 111d is in a cross shape and is located in the rib cavity 112, which is used to increase the self-strength and connection stability of the lattice monomer 111 and improve the tensile and compressive properties of the lattice monomer 111. It can be understood that the cross column 111d located in the rib cavity 112 can also play a certain role in intercepting and filtering impurities and foreign matters in the flowing cooling medium.

[0069] Correspondingly, the hollow grid 120 includes a plurality of grid plates 121, and the grid plates 121 are arranged in a staggered manner, so that the hollow grid 120 has a structure of a plurality of superimposed "field" characters. Grid holes 122 are formed between the plurality of grid plates 121. By providing the grid holes 122, it is convenient for the cooling medium to pass through, avoiding an obstructive effect on the flow of the cooling medium, and also playing a certain role in diverting the cooling medium.

[0070] It can be understood that the tube 200 is embedded in the lattice connection layer 110, and the extending direction of the tube 200 is the same as the overlapping arrangement direction of the lattice connection layer 110. The tube 200 also penetrates through the hollow grid 120, that is, both ends of the tube 200 connect the top side and the bottom side of the lattice support mechanism 100.

[0071] It should be understood that there are multiple tubes 200, which are used to place guide tubes and instrument tubes respectively. The number of tubes 200 for placing instrument tubes is one, and it is located at the center of the lattice support mechanism 100. The number of tubes 200 for placing guide tubes is twenty-four, which are arranged in two layers in an annular manner around the tubes 200 for placing instrument tubes, wherein the first layer has nine tubes 200, and the connection lines between the nine tubes 200 are rectangular; the second layer has fifteen tubes 200, and the connection lines between the fifteen tubes 200 are circular.

[0072] On this basis, the lower tube holder of the nuclear fuel assembly provided in this embodiment further includes a frame 300, which is sleeved on the outer side of the lattice connection layer 110 to limit the edge of the lattice connection layer 110. The top surface of the frame 300 is flush with the top surface of the topmost hollow grid 120, so that the upper components can be connected or placed.

[0073] Combination Figure 6 Specifically, the frame 300 is provided with four legs 310 around it, and each leg 310 is pentagonal, wherein two sides are connected to the four corners of the frame 300, so that the two sides are perpendicular to each other, which is beneficial to increase the surface area of ​​the legs 310 and the supporting strength for the frame 300.

[0074] In this embodiment, a pin hole 311 is provided on the support leg 310. There are two pin holes 311. The two pin holes 311 are respectively provided on the support legs 310 which are arranged diagonally. The positioning accuracy with the lower component can be increased by the cooperation between the positioning pin and the pin hole 311.

[0075] In summary, the present embodiment provides a lower tube socket of a nuclear fuel assembly, comprising a lower tube socket body 10, a tube 200, and a multi-layer lower tube socket support structure described in Example 1, wherein the tube 200 is embedded in the lattice connection layer 110, and the extension direction of the tube 200 is consistent with the arrangement direction of the lattice connection layer 110, and the tube 200 passes through the hollow grid 120, wherein the lattice monomer 111 and the hollow grid 120 are both structures described in Example 1. Therefore, the working principle of the lower tube socket of the nuclear fuel assembly provided in the present embodiment is as follows:

[0076] The lower tube seat of the nuclear fuel assembly includes a lattice support mechanism 100 and a tube 200 embedded in a lattice connection layer 110. The extension direction of the tube 200 is consistent with the arrangement direction of the lattice connection layer 110, and the tube 200 passes through the hollow grid 120. The cavity in the tube 200 is used to connect and position the guide tube and the instrument tube. The lattice connection layer 110 and the hollow grid 120 play a positioning role for the tube 200, so that the overall structure has a certain support strength, can conduct cooling medium, and is convenient for connecting the guide tube and the instrument tube.

[0077] Similarly, the lower tube seat of a nuclear fuel assembly provided by this embodiment has at least the following advantages: it meets the strength requirements while having good tensile and compressive properties; there are multiple gaps to facilitate the flow of the cooling medium; it is convenient to intercept impurities and foreign matter in the cooling medium to prevent them from contacting the fuel rods above and causing scratches on the fuel rods; it can divert the cooling medium flowing through to ensure the uniformity of the flow rate, so that the corresponding accessories of the nuclear fuel assembly can be fully and evenly cooled.

[0078] Example 3

[0079] This embodiment provides a nuclear fuel assembly, including a plurality of fuel elements, a connection assembly, an upper tube seat, a control rod guide tube and a positioning grid, and also includes the multi-layer structure lower tube seat support structure recorded in Example 1 or the nuclear fuel assembly lower tube seat of Example 2.

[0080] That is to say, the nuclear fuel assembly provided by the present invention includes a plurality of fuel elements, a connection assembly, an upper tube seat, a control rod guide tube and a positioning grid, a multi-layer structure lower tube seat support structure recorded in Example 1 or a nuclear fuel assembly lower tube seat recorded in Example 2 and other corresponding accessories. Therefore, the nuclear fuel assembly recorded in this embodiment has the beneficial technical effects recorded in Example 1, can ensure that it has sufficient strength, and is also convenient for the uniform circulation of the cooling medium.

[0081] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-layer lower pipe seat support structure, characterized in that: It comprises a dot matrix support mechanism (100), wherein the dot matrix support mechanism (100) comprises a dot matrix connection layer (110) and a hollow grid (120); The lattice connection layer (110) comprises at least two connected lattice monomers (111), the at least two lattice monomers (111) are arranged in parallel, and the ends of the at least two lattice monomers (111) are flush; The lattice monomer (111) is a polyhedral hollow structure, and both ends of the lattice monomer (111) are connected to the corresponding hollow grid (120).

2. A multi-layer lower pipe seat support structure according to claim 1, characterized in that: The lattice monomer (111) comprises a plurality of upper prisms (111a) and a plurality of lower prisms (111b), wherein the upper prisms (111a) and the lower prisms (111b) are arranged in a one-to-one correspondence; The top ends of the plurality of upper prisms (111a) are connected to each other, and the top ends of the upper prisms (111a) are connected to the hollow grid (120), and the bottom ends of the upper prisms (111a) are respectively connected to the top ends of the corresponding lower prisms (111b) to form a first reinforcement portion (111c); The bottom ends of the plurality of lower prisms (111b) are connected to each other, and the bottom ends of the lower prisms (111b) are connected to the corresponding hollow grid (120), and a prism cavity (112) is formed between the upper prism (111a) and the lower prism (111b); The top ends of the upper prisms (111a) in different lattice monomers (111) are flush with each other, and the bottom ends of the lower prisms (111b) in different lattice monomers (111) are flush with each other.

3. A multi-layer lower pipe seat support structure according to claim 2, characterized in that: The lattice monomer (111) further comprises a transverse column (111d), wherein the transverse column (111d) is located in the prism cavity (112), and both ends of the transverse column (111d) are respectively connected to corresponding first reinforcing portions (111c).

4. The multi-layer lower pipe seat support structure according to claim 1, characterized in that: The hollow grid (120) comprises a plurality of grid plates (121) arranged in a staggered manner, and grid holes (122) are formed between the plurality of grid plates (121).

5. The multi-layer lower pipe seat support structure according to claim 4, characterized in that: A second reinforcement part (123) is formed at the connection of the plurality of grid plates (121), and the second reinforcement part (123) is connected to both ends of the lattice monomer (111).

6. A lower tube socket of a nuclear fuel assembly, characterized in that: It comprises a lower tube seat body (10), a tube (200) and a multi-layer lower tube seat support structure as described in any one of claims 1 to 5, wherein the tube (200) is embedded in the lattice connection layer (110), and the extension direction of the tube (200) is consistent with the arrangement direction of the lattice connection layer (110), and the tube (200) passes through the hollow grid (120).

7. A lower tube socket for a nuclear fuel assembly according to claim 6, characterized in that: The lower tube seat body (10) further comprises a frame (300), wherein the frame (300) is sleeved outside the lattice connection layer (110).

8. The lower tube socket of a nuclear fuel assembly according to claim 7, characterized in that: The top surface of the frame (300) is flush with the top surface of the topmost hollow grid (120).

9. A lower tube socket for a nuclear fuel assembly according to claim 8, characterized in that: The frame (300) is provided with a support foot (310), and a pin hole (311) is provided on the support foot (310).

10. A nuclear fuel assembly, comprising a plurality of fuel elements, a connection assembly, an upper tube seat, a control rod guide tube and a spacer grid, characterized in that: It also includes the multi-layer structure lower tube seat support structure as described in any one of claims 1 to 5 or the nuclear fuel assembly lower tube seat as described in any one of claims 6 to 9.

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