Lower tube base of nuclear fuel assembly with restrained foreign body protection plate

Abstract

The present invention provides a lower tube seat of a nuclear fuel assembly containing a constrained anti-foreign matter plate, comprising a seat body and an anti-foreign matter plate, wherein the anti-foreign matter plate is transversely arranged on the upper side of the seat body, and comprises a plurality of baffles, wherein the plurality of baffles intersect to define a plurality of through holes, wherein the through holes longitudinally penetrate the anti-foreign matter plate, and the anti-foreign matter plate is also provided with a plurality of constrained holes matching the bottom ends of external fuel rods for the bottom ends of external fuel rods to sink into, wherein the inner walls of the constrained holes are inclined, and the apertures of the constrained holes gradually decrease from top to bottom. The constrained holes play a role in constraining the vibration of the fuel rods, reducing the flow-induced vibration of the fuel rods or the vibration of the fuel assembly caused by external forces, especially the vibration of the lower section of the fuel rods, and at the same time realizing the protective effect of the lower tube seat on the ends of the fuel rods, and avoiding the abrasion between the ends of the fuel rods and the lower tube seat caused by the flow-induced vibration. Since the anti-foreign matter plate is arranged on the upper side of the seat body, the anti-foreign matter plate can match seat bodies of various structures.

Description

Technical Field

[0001] The invention relates to the field of nuclear fuel assemblies, in particular to a lower tube seat of a nuclear fuel assembly containing a restrained foreign matter prevention plate. Background Art

[0002] A nuclear fuel assembly usually includes a number of fuel rods, a number of guide tubes and spacer grids, and an upper and lower tube base assemblies. The nuclear fuel assembly is located between the upper and lower plates of the reactor core. The coolant passes through the reserved plate holes in the core plate, enters the fuel rod bundle inside the fuel assembly from the lower tube base assembly, and flows out of the fuel assembly through the upper tube base assembly, taking away the heat generated by the nuclear reaction of the fuel rod bundle.

[0003] The lower tube base assembly serves as the lower end support of the fuel assembly and the coolant flow inlet. It needs to be able to support the fuel assembly and the force it transmits, as well as the fuel rod bundle. In addition to the supporting function, the performance of the lower tube base assembly design also lies in how to reduce the abrasion of the fuel rods caused by vibration, where the vibration may be caused by external forces such as transportation, or by the flow of coolant.

[0004] Therefore, how to design a lower tube seat that can limit the vibration of the fuel rod becomes 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 lower tube seat of a nuclear fuel assembly containing a constrained foreign matter prevention plate in view of the above-mentioned defects in the related technology.

[0006] The technical solution adopted by the present invention to solve its technical problems includes: providing a lower tube seat of a nuclear fuel assembly containing a constrained anti-foreign matter plate, including a seat body and an anti-foreign matter plate, wherein the anti-foreign matter plate is transversely arranged on the upper side of the seat body, and includes multiple partitions, and the multiple partitions intersect to define a plurality of through holes, and the through holes longitudinally penetrate the anti-foreign matter plate, and the anti-foreign matter plate is also provided with a plurality of constraint holes matching the bottom ends of external fuel rods for the bottom ends of external fuel rods to sink into, the inner walls of the constraint holes are inclined, and the apertures of the constraint holes gradually decrease from top to bottom.

[0007] Preferably, the constraining hole is in an inverted cone shape.

[0008] Preferably, the inclination of the inner wall of the constraint hole is consistent with the inclination of the bottom end of the external fuel rod.

[0009] Preferably, the upper opening diameter of the constraining hole is larger than the diameter of the conical end of the external fuel rod end plug.

[0010] Preferably, the foreign matter protection plate is provided with a plurality of guide tube assembly holes for assembly with the end of the external guide tube, and the guide tube assembly holes penetrate the foreign matter protection plate longitudinally.

[0011] Preferably, the partition includes a first plate body extending along a first direction and a second plate body extending along a second direction, the first direction intersects with the second direction, and the intersection of the first plate body and the second plate body defines a plurality of the through holes.

[0012] Preferably, the seat body comprises a first side wall and a second side wall connected to each other, the first direction is the same as an extension direction of the first side wall, and the second direction is the same as an extension direction of the second side wall; or

[0013] An angle is formed between the first direction and the extending direction of the first side wall, and an angle is formed between the second direction and the extending direction of the second side wall.

[0014] Preferably, the first direction is perpendicular to the second direction; and / or

[0015] The through holes are evenly distributed.

[0016] Preferably, the seat body includes a top plate arranged on the top, and a plurality of longitudinally penetrating water holes are arranged on the top, and the foreign body prevention plate is arranged on the upper side of the top plate.

[0017] Preferably, the through hole is communicated with the water flow hole, and the diameter of the water flow hole is larger than the diameter of the through hole.

[0018] The implementation of the technical solution of the present invention has at least the following beneficial effects: the constraint hole of the lower tube seat of the nuclear fuel assembly containing the constraint type anti-foreign matter plate of the present invention plays a role in constraining the vibration of the fuel rod, reducing the flow-induced vibration of the fuel rod or the vibration of the fuel assembly caused by external force, especially the vibration of the lower section of the fuel rod, and at the same time realizing the protective effect of the lower tube seat on the end of the fuel rod, avoiding the abrasion between the end of the fuel rod and the lower tube seat caused by the flow-induced vibration. Since the anti-foreign matter plate is arranged on the upper side of the seat body, the anti-foreign matter plate can match the seat bodies of various structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 It is a three-dimensional view of a lower tube seat of a nuclear fuel assembly containing a constrained foreign matter protection plate according to an embodiment of the present invention.

[0021] Figure 2 yes Figure 1 A partial enlarged view of the P site.

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

[0023] Figure 4 It is a stereoscopic view of a first embodiment of the foreign matter protection plate of the lower tube seat of the present invention.

[0024] Figure 5 yes Figure 4 Top view of the foreign body protection plate.

[0025] Figure 6 yes Figure 4 A partial three-dimensional view of the anti-foreign body plate.

[0026] Figure 7 yes Figure 4 A partial top view of the anti-foreign object plate.

[0027] Figure 8 yes Figure 7 Cross-sectional view at the AA position.

[0028] Fig. 9 yes Figure 4 Schematic diagram of the coordination between the foreign object protection plate and the lower end of the fuel rod (only a portion of the foreign object protection plate is shown).

[0029] Fig.10 yes Fig. 9 Cross-sectional view of the foreign body protection plate and the lower end of the fuel rod (the section position is Figure 7 AA position).

[0030] Fig.11 It is a top view of a second embodiment of the foreign matter protection plate of the lower tube seat of the present invention.

[0031] Fig.12 yes Fig.11 A partial enlarged view of the middle Q area.

[0032] The numbers in the figure indicate: lower tube seat 1, seat body 11, top plate 111, water flow hole 112, foreign matter protection plate 12, partition 121, first plate body 1211, second plate body 1212, through hole 122, constraint hole 123, guide tube assembly hole 124, fuel rod 21, first direction 31, second direction 32. DETAILED DESCRIPTION

[0033] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. It should be understood that if the orientation or position relationship indicated by "front", "rear", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail" and the like in the text is based on the orientation or position relationship shown in the drawings, constructed and operated in a specific orientation, it is only for the convenience of describing the present technical solution, and does not indicate that the device or element referred to must have a specific orientation, so it cannot be understood as a limitation of the present invention. It should also be noted that unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed", "set" and the like appear in the text, they should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intermediate elements. If the terms "first", "second", "third", etc. appear in the text, they are only for the convenience of describing the technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of the features. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0035] See also Figure 1-10 In one embodiment of the present invention, a lower tube seat 1 of a nuclear fuel assembly containing a constrained anti-foreign matter plate comprises a seat body 11 and an anti-foreign matter plate 12. The anti-foreign matter plate 12 is laterally fitted on the upper side of the seat body 11 and comprises a plurality of baffles 121. The plurality of baffles 121 intersect to define a plurality of through holes 122. The through holes 122 longitudinally penetrate the anti-foreign matter plate 12. The anti-foreign matter plate 12 is also provided with a plurality of constrained holes 123 that match the bottom ends of the external fuel rods 21 and are provided for the bottom ends of the external fuel rods 21 to sink into. The inner walls of the constrained holes 123 are inclined, and the aperture of the constrained holes 123 gradually decreases from top to bottom. Here, the external fuel rods 21 mean that the fuel rods 21 are external relative to the lower tube seat 1.

[0036] When the lower tube holder 1 of the nuclear fuel assembly containing the constrained foreign body anti-material plate 12 of the present invention is in use, the fuel rod 21 and the guide tube are arranged on the upper side of the lower tube holder 1, the lower tube holder 1 supports the guide tube and the fuel rod 21, the lower end of the fuel rod 21 is sunk into the constrained hole 123, the coolant passes through the through hole 122 of the foreign body anti-material plate 12, and the foreign body anti-material plate 12 plays the role of filtering and blocking foreign matter in the coolant water flow, thereby reducing the risk of foreign matter being caught in the nuclear fuel assembly and causing foreign matter abrasion and damage. The constrained hole 123 plays the role of constraining the vibration of the fuel rod 21, reducing the flow-induced vibration of the fuel rod 21 or the vibration of the fuel assembly caused by external force, especially the vibration of the lower section of the fuel rod 21, and at the same time realizing the protective effect of the lower tube holder 1 on the end of the fuel rod 21, avoiding the abrasion between the end of the fuel rod 21 and the lower tube holder 1 caused by the flow-induced vibration. Since the foreign matter prevention plate 12 is disposed on the upper side of the seat body 11 , the foreign matter prevention plate 12 can match the seat body 11 of various structures, such as a large flow hole tube seat or an array of small square hole tube seats.

[0037] See also Figure 6-8 Preferably, the constraint hole 123 is in an inverted cone shape, so as to better match the shape of the end of the fuel rod 21. Figure 9-10 The aperture of the upper opening of the constraint hole 123 is larger than the diameter of the tapered end of the end plug of the external fuel rod 21, and the aperture of the lower opening of the constraint hole 123 is smaller than the diameter of the tapered end of the end plug of the external fuel rod 21. The inclination of the inner wall of the constraint hole 123 is consistent with the inclination of the bottom end of the external fuel rod 21. The aperture of the upper opening of the constraint hole 123 is larger than the aperture of the through hole 122. The aperture of the lower opening of the constraint hole 123 is smaller than the aperture of the through hole 122.

[0038] See also Figure 4-5 Preferably, the foreign body protection plate 12 is provided with a plurality of guide tube assembly holes 124 for assembly with the ends of the external guide tubes, and the guide tube assembly holes 124 longitudinally penetrate the foreign body protection plate 12. Here, the external guide tube means that the guide tube is external relative to the lower tube seat. The aperture of the guide tube assembly hole 124 is larger than the aperture of the constraint hole 123.

[0039] See also Figure 6-7 Preferably, the partition 121 includes a first plate body 1211 extending along the first direction 31 and a second plate body 1212 extending along the second direction 32 , the first direction 31 is not parallel to the second direction 32 , and the first plate body 1211 and the second plate body 1212 intersect to define a plurality of through holes 122 .

[0040] Further preferably, the seat body 11 includes a first side wall 113 and a second side wall 114 connected to each other, the first direction 31 is the same as the extension direction of the first side wall 113, and the second direction 32 is the same as the extension direction of the second side wall 114; or, there is an angle between the first direction 31 and the extension direction of the first side wall 113, and there is an angle between the second direction 32 and the extension direction of the second side wall 114. Specifically, the seat body 11 includes a first side wall 113 and a second side wall 114 connected to each other. In some embodiments, see Figure 4-7 , the first direction 31 is the same as the extension direction of the first side wall 113, and the second direction 32 is the same as the extension direction of the second side wall 114, so that the first plate 1211 is parallel to the first side wall 113, and the second plate 1212 is parallel to the second side wall 114; in other embodiments, see Fig.11 and 12 There is an angle between the first direction 31 and the extension direction of the first side wall 113 , and there is an angle between the second direction 32 and the extension direction of the second side wall 114 , so that the first plate body 1211 is inclined relative to the first side wall 113 , and the second plate body 1212 is inclined relative to the second side wall 114 .

[0041] More preferably, see Figure 7 , the first direction 31 is perpendicular to the second direction 32, the first plate 1211 is perpendicular to the second plate 1212, the defined through hole 122 is a square hole, and the multiple through holes have the same shape. Alternatively, the first direction 31 may not be perpendicular to the second direction 32, the first plate 1211 is not perpendicular to the second plate 1212, and the defined multiple through holes have different shapes. It should be understood that the shapes of the multiple through holes may be the same or different, without limitation.

[0042] See also Figure 4-7 Preferably, the through holes 122 are evenly distributed, so that the flow field of the coolant is more uniform and the flow-induced vibration of the fuel rod 21 is gradually reduced.

[0043] See also Figure 1 and 3 Preferably, the seat body 11 includes a top plate 111 disposed on the top, and a plurality of longitudinally penetrating water flow holes 112 are disposed on the top, and the foreign matter prevention plate 12 is disposed on the upper side of the top plate 111. The through hole 122 is connected to the water flow hole 112, and the aperture of the water flow hole 112 is larger than the aperture of the through hole 122.

[0044] In summary, when the lower tube holder 1 of the nuclear fuel assembly containing the constrained anti-foreign matter plate 12 of the present invention is in use, the fuel rod 21 and the guide tube are arranged on the upper side of the lower tube holder 1, the lower tube holder 1 supports the guide tube and the fuel rod 21, the lower end of the fuel rod 21 is sunk into the constrained hole 123, the coolant passes through the through hole 122 of the anti-foreign matter plate 12, and the anti-foreign matter plate 12 plays the role of filtering and blocking foreign matter in the coolant water flow, thereby reducing the risk of foreign matter being caught in the nuclear fuel assembly and causing foreign matter abrasion and damage. The constrained hole 123 plays the role of constraining the vibration of the fuel rod 21, reducing the flow-induced vibration of the fuel rod 21 or the vibration of the fuel assembly caused by external force, especially the vibration of the lower section of the fuel rod 21, and at the same time realizing the protective effect of the lower tube holder 1 on the end of the fuel rod 21, avoiding the abrasion between the end of the fuel rod 21 and the lower tube holder 1 caused by the flow-induced vibration. Since the foreign object protection plate 12 is disposed on the upper side of the seat body 11, the foreign object protection plate 12 can match the seat body 11 of various structures, such as a large flow hole tube seat or an array of small square hole tube seats. The through holes 122 are evenly distributed, so that the flow field of the coolant is more uniform, and the flow-induced vibration of the fuel rod 21 is gradually reduced.

[0045] The above description is only the preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications, combinations and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A lower tube seat (1) of a nuclear fuel assembly having a constrained foreign matter prevention plate, characterized in that: The invention comprises a seat body (11) and a foreign matter prevention plate (12), wherein the foreign matter prevention plate (12) is transversely arranged on the upper side of the seat body (11) and comprises a plurality of baffles (121), wherein the plurality of baffles (121) intersect to define a plurality of through holes (122), wherein the through holes (122) longitudinally penetrate the foreign matter prevention plate (12), and the foreign matter prevention plate (12) is further provided with a plurality of restraining holes (123) matching with the bottom ends of the external fuel rods (21) and allowing the bottom ends of the external fuel rods (21) to sink into. The inner wall of the hole (123) is inclined, the aperture of the constraint hole (123) gradually decreases from top to bottom, the inclination of the inner wall of the constraint hole (123) is consistent with the inclination of the bottom end of the external fuel rod (21), the upper opening aperture of the constraint hole (123) is larger than the diameter of the tapered end of the end plug of the external fuel rod (21), and the lower opening aperture of the constraint hole (123) is smaller than the diameter of the tapered end of the end plug of the external fuel rod (21), so that the lower end of the fuel rod (21) is sunk into the constraint hole (123).

2. The lower tube seat (1) according to claim 1, characterized in that: The restraining hole (123) is in an inverted cone shape.

3. The lower tube seat (1) according to claim 1, characterized in that: The foreign matter prevention plate (12) is provided with a plurality of guide tube assembly holes (124) for assembly with the ends of external guide tubes, and the guide tube assembly holes (124) penetrate the foreign matter prevention plate (12) longitudinally.

4. The lower tube seat (1) according to any one of claims 1 to 3, characterized in that: The partition (121) comprises a first plate body (1211) extending along a first direction (31) and a second plate body (1212) extending along a second direction (32), the first direction (31) intersects with the second direction (32), and the first plate body (1211) and the second plate body (1212) intersect to define a plurality of through holes (122).

5. The lower tube seat (1) according to claim 4, characterized in that: The seat body (11) comprises a first side wall (113) and a second side wall (114) connected to each other, the first direction (31) is the same as an extension direction of the first side wall (113), and the second direction (32) is the same as an extension direction of the second side wall (114); or There is an angle between the first direction (31) and the extension direction of the first side wall (113), and there is an angle between the second direction (32) and the extension direction of the second side wall (114).

6. The lower tube seat (1) according to claim 4, characterized in that: The first direction (31) is perpendicular to the second direction (32); and / or The through holes (122) are evenly distributed.

7. The lower tube seat (1) according to any one of claims 1 to 3, characterized in that: The seat body (11) comprises a top plate (111) arranged at the top, and a plurality of longitudinally penetrating water flow holes (112) are provided on the top, and the foreign matter prevention plate (12) is arranged on the upper side of the top plate (111).

8. The lower tube seat (1) according to claim 7, characterized in that: The through hole (122) is in communication with the water flow hole (112), and the diameter of the water flow hole (112) is larger than the diameter of the through hole (122).

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