Nuclear fuel assembly lower nozzle limiting fuel rod vibration

Abstract

The application provides a nuclear fuel assembly lower nozzle for limiting fuel rod vibration, comprising a nozzle body, a plurality of assembly column flow channel pipe units and a plurality of main flow channel pipes through which liquid passes, the nozzle body has an upwardly open cavity, the main flow channel pipes and the assembly column flow channel pipe units are arranged side by side in the cavity in the transverse direction; the assembly column flow channel pipe unit comprises a guide pipe assembly column and at least two assembly column side flow channel pipes through which liquid passes, the main flow channel pipes and the assembly column side flow channel pipes both comprise limiting inclined surfaces arranged on the upper end side face, and the limiting inclined surfaces enclose a recess structure into which the end part of an external fuel rod is capable of sinking. The nuclear fuel assembly lower nozzle of the application can realize the limiting effect on the end part of the fuel rod and further reduce the flow-induced vibration of the fuel rod; the longitudinal through structure of the main flow channel pipes and the assembly column side flow channel pipes can be used for the cooling liquid to pass through, the axial flow of the cooling liquid is more uniform, the cross flow between the fuel rod bundles is reduced, and thus the flow-induced vibration of the fuel rod is reduced.

Description

Technical Field

[0001] This invention relates to the field of nuclear fuel assemblies, and more particularly to a lower tube holder for nuclear fuel assemblies that limits the vibration of fuel rods. Background Technology

[0002] A nuclear fuel assembly typically consists of several fuel rods, several guide tubes and positioning grids, as well as an upper and lower tube assembly. The nuclear fuel assembly is located between the upper and lower plates of the reactor core. Coolant enters the fuel rod bundle inside the fuel assembly through pre-drilled holes in the core plates, flows out of the fuel assembly through the lower tube assembly, and carries away the heat generated by the nuclear reaction in the fuel rod bundle.

[0003] As the lower end support of the fuel assembly and the coolant flow inlet, the lower tube seat assembly needs to be able to support the fuel assembly and the forces it transmits, as well as support the fuel rod bundle. In addition to the support function, the performance of the lower tube seat assembly design also depends on how to obtain better hydraulic performance (such as a more uniform coolant flow field) and reduce the erosion of the fuel rods caused by vibration. Vibration may be caused by external forces such as transportation, or it may be caused by the flow of coolant.

[0004] Therefore, designing a lower tube seat that can achieve a more uniform coolant flow field and limit fuel rod vibration has become an urgent problem to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a nuclear fuel assembly lower tube seat that provides uniform flow field and limits the vibration of fuel rods, in order to address the above-mentioned deficiencies in related technologies.

[0006] The technical solution adopted by the present invention to solve its technical problem includes: providing a nuclear fuel assembly lower tube seat for limiting fuel rod vibration, including a seat body, multiple assembly column flow channel tube units and multiple main flow channel tubes for liquid to pass through, wherein the seat body has an upwardly open cavity, and the main flow channel tubes and the assembly column flow channel tube units are arranged side by side in the cavity in the transverse direction.

[0007] The assembly column flow channel unit includes a guide tube assembly column and at least two assembly column side flow channels for liquid passage. The assembly column side flow channels are arranged side by side on the outer periphery of the guide tube assembly column in the transverse direction. The main flow channel and the assembly column side flow channels are both longitudinally continuous. The top of the guide tube assembly column is configured for assembling the end of an external guide tube. The main flow channel and the assembly column side flow channels both include a limiting slope on the upper side. Adjacent main flow channels and the limiting slope of the main flow channel, as well as adjacent main flow channels and the limiting slope of the assembly column side flow channels, form an upwardly open recessed structure for the end of an external fuel rod to be inserted.

[0008] Preferably, the guide tube assembly column is provided with a longitudinally penetrating hole structure for configuration with an external guide tube.

[0009] Preferably, the hole structure includes a countersunk hole at the upper end of the assembly column and a through hole communicating with the countersunk hole and located below the countersunk hole.

[0010] Preferably, the main channel pipe is prismatic in shape, and the limiting inclined surface is located at the edge of the main channel pipe and is inclined relative to the edge.

[0011] Preferably, the main channel pipe is a quadrangular prism, and the number of limiting inclined surfaces is at least four, respectively disposed at the four edges of the main channel pipe.

[0012] Preferably, the seat includes a frame that defines the cavity. The upper inner side of the frame has a recess that opens upward and inward into the frame. The position of the limiting slope of part of the main flow channel or the assembly column side flow channel corresponds to the recess. The inner wall of the recess is inclined and the inclination direction is opposite to the limiting slope. The limiting slope and the recess together define the recessed structure.

[0013] Preferably, the recessed structure is inverted conical; and / or the limiting inclined surface is a recessed arc surface.

[0014] Preferably, the assembly column side flow channel includes a matching side that matches the outer side of the guide tube assembly column, and the matching side abuts against the outer side of the guide tube assembly column.

[0015] Preferably, the guide tube assembly column is cylindrical in shape, and the mating side is a concave arc surface.

[0016] Preferably, the assembly column-side flow channel includes multiple outer longitudinal planes, adjacent longitudinal planes intersect to form an edge, and the limiting inclined surface is provided at the edge and inclined relative to the edge.

[0017] Preferably, the lower tube seat includes a transversely arranged anti-foreign object plate disposed in the cavity of the seat body. The assembly column flow channel unit and the main flow channel are disposed on the upper side of the anti-foreign object plate. The anti-foreign object plate is provided with a plurality of longitudinally penetrating filter holes for liquid to pass through and corresponding longitudinally penetrating holes below the guide tube assembly column. Some of the filter holes are disposed on the lower side of the main flow channel and communicate with the cavity of the main flow channel. Some of the filter holes are disposed on the lower side of the assembly column side flow channel and communicate with the cavity of the assembly column side flow channel.

[0018] The technical solution of the present invention has at least the following beneficial effects: the lower tube seat of the nuclear fuel assembly of the present invention can realize the limiting effect on the end of the fuel rod, further reducing the flow-induced vibration of the fuel rod; the longitudinal through structure of the main flow channel and the side flow channel of the assembly column allows the coolant to pass through, making the axial flow of the coolant more uniform, reducing the cross flow between the fuel rod bundles, thereby reducing the flow-induced vibration of the fuel rod. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a perspective view of a nuclear fuel assembly lower tube seat that provides uniform flow field and restricts fuel rod vibration according to one embodiment of the present invention.

[0021] Figure 2 yes Figure 1 A magnified view of part A in the middle.

[0022] Figure 3 yes Figure 1 A three-dimensional view of the lower tube seat.

[0023] Figure 4 yes Figure 3 A magnified view of part B in the middle.

[0024] Figure 5 yes Figure 1 A three-dimensional view of the anti-foreign object plate of the lower pipe seat.

[0025] Figure 6 yes Figure 5 A magnified view of part C in the middle.

[0026] Figure 7 yes Figure 1 A three-dimensional view of the lower tube seat body and the foreign object protection plate.

[0027] Figure 8 yes Figure 1 A three-dimensional view of the main channel pipe of the lower pipe seat.

[0028] Figure 9 yes Figure 1 A three-dimensional view of the guide tube assembly column of the lower tube seat.

[0029] Figure 10 yes Figure 9 The front view of the guide tube assembly column.

[0030] Figure 11 yes Figure 9 A cross-sectional view of position AA.

[0031] Figure 12 yes Figure 1 A three-dimensional view of the assembly column-side flow channel pipe of the lower pipe seat.

[0032] Figure 13 yes Figure 12 Top view of the assembly column-side flow channel pipe.

[0033] Figure 14 yes Figure 1 A schematic diagram showing the assembly status of the two main flow channels of the lower pipe seat and the bottom of the fuel rod (only the bottom of the fuel rod is shown).

[0034] The labels in the diagram represent: lower tube seat 1, seat body 11, frame body 111, recess 1111, cavity 1112, assembly column flow channel unit 12, guide tube assembly column 121, hole structure 1211, countersunk hole 12111, through hole 12112, assembly column side flow channel 122, matching side 1221, longitudinal plane 1222, main flow channel 13, limiting slope 14, recessed structure 15, foreign object protection plate 16, filter hole 161, corresponding hole 162, fuel rod 21, transverse 31, longitudinal 32. Detailed Implementation

[0035] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described in detail with reference to the accompanying drawings. It should be understood that if terms such as "upper," "lower," "longitudinal," "horizontal," "top," or "bottom" appear in the text, indicating orientation or positional relationships based on the orientation or positional relationships shown in the drawings, or indicating construction and operation in a specific orientation, they are merely for the convenience of describing the technical solution and do not indicate that the device or element referred to must have a specific orientation; therefore, they should not be construed as limitations on this invention. It should also be noted that unless otherwise explicitly specified and limited, terms such as "install," "connect," "join," "fix," or "set" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or integration; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two elements or the interaction between two elements. When an element is referred to as being "above" or "below" another element, the element can be located "directly" or "indirectly" on top of the other element, or there may be one or more intermediary elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0037] Please see Figures 1 to 3 The nuclear fuel assembly lower tube seat 1 with uniform flow field and limited fuel rod vibration in one embodiment of the present invention includes a seat body 11, a plurality of assembly column flow channel tube units 12 and a plurality of main flow channel tubes 13 for liquid to pass through. The seat body 11 has an upwardly open cavity 1112. The main flow channel tubes 13 and the assembly column flow channel tube units 12 are arranged side by side in the cavity 1112 in the transverse direction 31.

[0038] The assembly column flow channel unit 12 includes a guide tube assembly column 121 and at least two assembly column side flow channels 122 for liquid passage. The assembly column side flow channels 122 are arranged side by side around the guide tube assembly column 121 in the transverse direction 31. The main flow channel 13 and the assembly column side flow channels 122 are both longitudinally continuous. The top end of the guide tube assembly column 121 is configured to assemble and support the end of the external guide tube. The main flow channel 13 and the assembly column side flow channels 122 both include a limiting slope 14 on the upper side. Adjacent main flow channels 13 and their limiting slopes 14, and adjacent main flow channels 13 and their limiting slopes 14, form an upwardly open recessed structure 15 for the end of the external fuel rod 21 to be recessed, which is used to limit the vibration of the fuel rod 21. Here, "external guide tube" and "external fuel rod 21" mean that the guide tube and the fuel rod 21 are external relative to the lower tube seat.

[0039] Nuclear fuel assemblies typically include several fuel rods 21 and guide tubes. In use, the lower tube seat 1 of the nuclear fuel assembly of the present invention has the fuel rods 21 and guide tubes arranged longitudinally 32. The bottom end of the guide tube is assembled with the top end of the guide tube assembly column 121, which supports the guide tube. The recessed structure 15 is similar to the outer contour of the end structure of the fuel rod 21. All or part of the bottom end of the fuel rod 21 is embedded in the recessed structure 15, which realizes the limiting effect of the lower tube seat 1 on the end of the fuel rod 21, further reducing the flow-induced vibration of the fuel rod 21, especially the vibration of the lower section of the fuel rod 21. At the same time, it realizes the protection effect of the lower tube seat 1 on the end of the fuel rod 21, avoiding the erosion between the end of the fuel rod 21 and the lower tube seat 1 caused by flow-induced vibration. The longitudinally 32 through structure of the main flow channel 13 and the side flow channel 122 of the assembly column allows coolant to pass through, making the axial flow of coolant more uniform, reducing the crossflow between the fuel rods 21 bundle, thereby reducing the flow-induced vibration of the fuel rods 21.

[0040] See Figure 9-11 Preferably, the guide tube assembly post 121 is provided with a longitudinally penetrating hole structure 1211 for configuration with an external guide tube. The hole structure 1211 allows fasteners such as screws to pass through, enabling assembly with the guide tube. The hole structure 1211 includes a countersunk hole 12111 at the upper end of the assembly post and a through hole 12112 communicating with the countersunk hole 12111 and located below the countersunk hole 12111.

[0041] See Figure 8 and 14 Preferably, the main channel pipe 13 is prismatic in shape, and the limiting inclined surface 14 is provided at the edge of the main channel pipe 13 and inclined relative to the edge and relative to the side of the main channel pipe 13. The main channel pipe 13 is a quadrangular prism, and the number of limiting inclined surfaces 14 is at least four, respectively provided at the four edges of the main channel pipe 13. See Figure 3-4 The seat 11 includes a frame 111, which defines a cavity 1112. The upper inner side of the frame 111 is provided with a recess 1111, which is open upward and inward to the frame 111. The position of the limiting slope 14 of part of the main channel pipe 13 or the assembly column side channel pipe 122 corresponds to the recess 1111. The inner wall of the recess 1111 is inclined and the inclination direction is opposite to the limiting slope 14. The limiting slope 14 and the recess 1111 together define a recessed structure 15.

[0042] See Figure 2 , 8 Preferably, the recessed structure 15 is inverted conical in shape. The limiting slope 14 is a recessed arc surface, so as to better fit the end shape of the fuel rod 21.

[0043] See Figure 12-13 Preferably, the assembly column-side flow channel 122 includes a matching side surface 1221 that matches the outer side surface of the guide tube assembly column 121. The matching side surface 1221 abuts against the outer side surface of the guide tube assembly column 121, thereby making the matching side surface 1221 fit more closely to the side surface of the guide tube assembly column 121. The guide tube assembly column 121 is cylindrical in shape, and the matching side surface 1221 of the assembly column-side flow channel 122 is a concave arc surface. The assembly column-side flow channel 122 includes multiple outer longitudinal planes 1222, and adjacent longitudinal planes 1222 intersect to form an edge. A limiting inclined surface 14 is provided at the edge and is inclined relative to the edge.

[0044] See Figure 5-7Preferably, the lower tube seat 1 includes a transversely arranged anti-foreign object plate 16 disposed in the cavity 1112 of the seat body 11. The assembly column flow channel unit 12 and the main flow channel 13 are disposed on the upper side of the anti-foreign object plate 16. The anti-foreign object plate 16 is provided with a plurality of longitudinally 32 through filter holes 161 for liquid to pass through, and corresponding longitudinally 32 through holes 162 below the guide tube assembly column 121. Some filter holes 161 are disposed on the lower side of the main flow channel 13 and communicate with the hollow cavity 1112 of the main flow channel 13. Some filter holes 161 are disposed on the lower side of the assembly column side flow channel 122 and communicate with the hollow cavity 1112 of the assembly column side flow channel 122. When the nuclear fuel assembly of the present invention is in use, the coolant enters the fuel assembly through the filter holes 161 of the foreign object protection plate 16, the hollow channel of the main flow channel 13, and the hollow channel of the assembly column side flow channel 122. The foreign object protection plate 16 plays the role of filtering and blocking foreign objects in the coolant water flow, thereby reducing the risk of foreign objects getting stuck in the nuclear fuel assembly and causing foreign object abrasion and damage.

[0045] In summary, the lower tube seat 1 of the nuclear fuel assembly of the present invention can distribute coolant into the fuel assembly. The coolant liquid passes through the hollow channels of the main flow channel 13 and the side flow channel 122 of the assembly column, making the axial flow of the coolant more uniform and reducing the crossflow between the fuel rods 21, thereby reducing the flow-induced vibration of the fuel rods 21. It can also limit the vibration of the fuel rods 21 by the recessed structure 15, and at the same time realize the protection of the ends of the fuel rods 21 by the lower tube seat 1, avoiding the erosion between the ends of the fuel rods 21 and the lower tube seat 1 caused by flow-induced vibration. The guide tube assembly column 121 supports the guide tube and can withstand the loads under operation, hoisting and accident conditions. The foreign object protection plate 16 can prevent foreign objects in the coolant from entering the reactor core.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can have various modifications, combinations, and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A nuclear fuel assembly lower tube holder (1) for limiting fuel rod vibration, characterized in that, It includes a base (11), multiple assembly column flow channel units (12) and multiple main flow channels (13) for liquid to pass through. The base (11) has an upwardly open cavity (1112). Each of the main flow channels (13) and each of the assembly column flow channel units (12) are separate components and are arranged side by side in the cavity (1112) in the transverse direction (31). The assembly column flow channel unit (12) includes a guide tube assembly column (121) and at least two assembly column side flow channels (122) for liquid passage. The assembly column side flow channels (122) are arranged side by side on the periphery of the guide tube assembly column (121) in the transverse direction (31). The guide tube assembly column (121) and each of the assembly column side flow channels (122) are separate components. The main flow channel (13) and the assembly column side flow channels (122) are both longitudinally connected. The guide tube assembly column (121) The top end of 121) is configured for assembling the end of the external guide tube; both the main flow channel (13) and the assembly column side flow channel (122) include a limiting slope (14) provided on the upper side. The adjacent main flow channel (13) and the limiting slope (14) of the main flow channel (13), and the adjacent main flow channel (13) and the limiting slope (14) of the assembly column side flow channel (122) form an upwardly open recessed structure (15) for the end of the external fuel rod (21) to be inserted.

2. The lower tube seat (1) according to claim 1, characterized in that, The guide tube assembly column (121) is provided with a longitudinal (32) through hole structure (1211) for configuration with an external guide tube; the hole structure (1211) includes a countersunk hole (12111) at the upper end of the assembly column and a through hole (12112) connecting the countersunk hole (12111) and located below the countersunk hole (12111).

3. The lower tube seat (1) according to claim 1, characterized in that, The main channel pipe (13) is prismatic in shape, and the limiting inclined surface (14) is located at the edge of the main channel pipe (13) and is inclined relative to the edge.

4. The lower tube seat (1) according to claim 3, characterized in that, The main channel pipe (13) is a quadrangular prism, and the number of limiting inclined surfaces (14) is at least four, which are respectively located at the four edges of the main channel pipe (13).

5. The lower tube seat (1) according to claim 3, characterized in that, The seat (11) includes a frame (111) that defines the cavity (1112). The upper inner side of the frame (111) is provided with a recess (1111) that is open upward and inward to the frame (111). The position of the limiting slope (14) of part of the main channel pipe (13) or the assembly column side channel pipe (122) corresponds to the recess (1111). The inner wall of the recess (1111) is inclined and the inclination direction is opposite to the limiting slope (14). The limiting slope (14) and the recess (1111) together define the recessed structure (15).

6. The lower tube seat (1) according to claim 1, characterized in that, The recessed structure (15) is inverted conical in shape; and / or The limiting inclined surface (14) is a concave arc surface.

7. The lower tube seat (1) according to claim 1, characterized in that, The assembly column side flow channel (122) includes a matching side (1221) that matches the outer side of the guide tube assembly column (121), and the matching side (1221) abuts against the outer side of the guide tube assembly column (121).

8. The lower tube seat (1) according to claim 7, characterized in that, The guide tube assembly column (121) is cylindrical in shape, and the matching side (1221) is a concave arc surface.

9. The lower tube seat (1) according to claim 8, characterized in that, The assembly column-side flow channel (122) includes a plurality of outer longitudinal planes (1222), adjacent longitudinal planes (1222) intersect to form an edge, and the limiting inclined surface (14) is provided at the edge and inclined relative to the edge.

10. The lower tube seat (1) according to claim 1, characterized in that, The lower tube seat (1) includes a foreign object prevention plate (16) arranged laterally (31) in the cavity (1112) of the seat body (11). The assembly column flow channel unit (12) and the main flow channel (13) are arranged on the upper side of the foreign object prevention plate (16). The foreign object prevention plate (16) is provided with a plurality of longitudinally (32) through filter holes (161) for liquid to pass through and corresponding holes (162) that are longitudinally (32) through below the guide tube assembly column (121). Some of the filter holes (161) are arranged on the lower side of the main flow channel (13) and communicate with the cavity (1112) of the main flow channel (13). Some of the filter holes (161) are arranged on the lower side of the assembly column side flow channel (122) and communicate with the cavity (1112) of the assembly column side flow channel (122).

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