Nuclear fuel assembly upper nozzle

Abstract

The application discloses a nuclear fuel assembly upper tube seat, which comprises a seat body, a plurality of quick-release assemblies and a cover plate assembly. Each quick-release assembly comprises a bottom plate spring, a plurality of action plate springs and a quick-release positioning piece, and the cover plate assembly comprises at least two cover plate pieces which are detachably connected. The nuclear fuel assembly upper tube seat can compensate for the deficiency of the pressing force, reduce the initial compression amount of the fuel assembly pressing spring of the whole reactor core, effectively reduce the risk of fuel assembly bending caused by excessive fuel assembly pressing force, and adapt to various types of fuel assemblies by adjusting the thickness of the at least two cover plate pieces to change the overall height of the nuclear fuel assembly upper tube seat and meet the different pressing force requirements of different fuel assemblies.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of reactor nuclear fuel, in particular to a nuclear fuel assembly upper nozzle. BACKGROUND

[0002] In the existing pressurized water reactor, in order to ensure the compaction of the fuel assembly, the initial compression amount of the compaction spring needs to be conservatively considered the compaction of the minimum height fuel assembly (i.e. new fuel assembly), so that the compaction force of the end-of-life fuel assembly is too conservative, which is easy to cause the bending problem of the fuel assembly. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a nuclear fuel assembly upper nozzle.

[0004] The technical scheme adopted by the present application to solve the technical problem is: a nuclear fuel assembly upper nozzle is constructed, which comprises a seat body, a plurality of quick release assemblies and a cover plate assembly;

[0005] Each quick release assembly comprises a bottom plate spring, a plurality of action plate springs and a quick release positioning piece, the plurality of action plate springs are stacked and arranged above the bottom plate spring, the quick release positioning piece is arranged through the bottom plate spring and the plurality of action plate springs, the bottom plate spring is abutted on the upper end surface of the seat body, the lower end of the quick release positioning piece is connected to the bottom plate spring, and the upper end of the quick release positioning piece is connected to the cover plate assembly.

[0006] The cover plate assembly comprises at least two cover plate pieces, and the at least two cover plate pieces are detachably connected.

[0007] In some embodiments, a first through hole is formed in the bottom plate spring, a second through hole corresponding to the first through hole is formed in the action plate spring, and the quick release positioning piece is arranged through the first through hole and the second through hole.

[0008] In some embodiments, a hook portion is arranged at one end of the bottom plate spring away from the first through hole, a communication hole is arranged at one end of the action plate spring away from the second through hole, and the hook portion is arranged through the communication hole.

[0009] In some embodiments, the number of cover plate pieces is two, the two cover plate pieces are divided into a first installation cover plate and a second installation cover plate, and the second installation cover plate is arranged above the first installation cover plate.

[0010] A first connecting hole corresponding to the quick release positioning piece is arranged on the first installation cover plate, and a second connecting hole corresponding to the first connecting hole is arranged on the second installation cover plate.

[0011] In some embodiments, the upper tube support of the nuclear fuel assembly further comprises a limiting piece, the seat body is provided with a first limiting hole, the first mounting cover plate is provided with a second limiting hole corresponding to the first limiting hole, and two ends of the limiting piece are connected to the first limiting hole and the second limiting hole respectively.

[0012] In some embodiments, the seat body is provided with a first docking hole, the first mounting cover plate is provided with a second docking hole corresponding to the first docking hole, and the second mounting cover plate is provided with a third docking hole corresponding to the second docking hole.

[0013] In some embodiments, the distance between the lower end surface of the first mounting cover plate and the upper end surface of the second mounting cover plate is 15mm to 30mm.

[0014] In some embodiments, the number of quick release assemblies is four.

[0015] In some embodiments, the number of action plate springs is three.

[0016] In some embodiments, the bottom plate spring and the plurality of action plate springs are both bent plate-shaped spring pieces.

[0017] The present application has the following beneficial effects: the upper tube support of the nuclear fuel assembly compensates for the lack of compression force by setting the quick release assembly and the cover plate assembly, reduces the initial compression amount of the fuel assembly compression spring of the whole core, and effectively reduces the risk of fuel assembly bending caused by excessive fuel assembly compression force. At least two cover plate pieces are provided and detachably connected between the at least two cover plate pieces. By adjusting the thickness of the at least two cover plate pieces, the overall height of the upper tube support of the nuclear fuel assembly changes, thereby meeting the different compression force requirements of different fuel assemblies to adapt to various types of fuel assemblies. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the present application, the present application will be further described below in combination with the drawings and embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor. In the drawings:

[0019] Figure 1 is an application schematic diagram of the upper tube support of the nuclear fuel assembly in some embodiments of the present application;

[0020] Figure 2 is a structural schematic diagram of the cover plate assembly in some embodiments of the present application;

[0021] Figure 3is a component exploded view of the upper nozzle of the nuclear fuel assembly in some embodiments of the present application;

[0022] Figure 4 is a general structure view of the upper nozzle of the nuclear fuel assembly in some embodiments of the present application;

[0023] Figure 5 is a structure view of the quick release assembly in some embodiments of the present application;

[0024] Figure 6 is a structure view of the bottom plate spring in some embodiments of the present application;

[0025] Figure 7 is a structure view of the action plate spring in some embodiments of the present application. DETAILED DESCRIPTION

[0026] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "upper", "lower", "left", "right", "vertical", "horizontal", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail" and the like are based on the directions or positional relationships shown in the drawings, constructed and operated in a particular direction, and are only for the convenience of describing the technical solutions, and should not be understood as indicating that the devices or elements referred to must have a particular direction, and therefore should not be understood as limiting the present application.

[0027] It should also be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing", "setting" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements. When an element is referred to as "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there can be one or more intervening elements. The terms "first", "second", "third" and the like are only for the convenience of describing the technical solutions, and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features with "first", "second", "third" and the like can explicitly or implicitly include one or more of the features. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0028] Reference Figures 1 to 7The upper fuel assembly nozzle is one of the nuclear fuel assembly nozzles in some embodiments of the application, which comprises a seat body 1, a plurality of quick-release assemblies 2 and a cover plate assembly 3. Each quick-release assembly 2 comprises a bottom plate spring 21, a plurality of action plate springs 22 and a quick-release positioning piece 23. The plurality of action plate springs 22 are stacked and arranged above the bottom plate spring 21. The quick-release positioning piece 23 is arranged through the bottom plate spring 21 and the plurality of action plate springs 22. The bottom plate spring 21 is abutted on the upper end surface of the seat body 1. The lower end of the quick-release positioning piece 23 is clamped below the bottom plate spring 21. The upper end of the quick-release positioning piece 23 is connected to the cover plate assembly 3. The cover plate assembly 3 comprises at least two cover plate pieces which are detachably connected. Preferably, the number of the quick-release assemblies 2 is four.

[0029] It can be understood that in a pressurized water reactor, the lower fuel assembly nozzle is seated on the lower core plate, and the upper core plate is pressed on the fuel assembly compression system. During operation, due to the different neutron fluxes in different regions, the skeleton growth of fuel assemblies at different positions is different, thereby causing the compression amount of the compression system to be different, resulting in a large difference in compression force. Since the growth amount of the irradiated fuel assembly is greater than that of the newly entered fuel assembly, by installing the quick-release assembly 2 and the cover plate assembly 3 on the seat body 1 of the upper fuel assembly nozzle, the deficiency of the compression force is compensated, and at the same time, the initial compression amount of the fuel assembly compression spring in the whole core is reduced, which can effectively reduce the risk of fuel assembly bending caused by excessive fuel assembly compression force. At the same time, at least two cover plate pieces are arranged, and the at least two cover plate pieces are detachably connected. By adjusting the thickness of the at least two cover plate pieces, the overall height of the upper fuel assembly nozzle can be changed, thereby meeting the different compression force requirements of different fuel assemblies to adapt to various types of fuel assemblies.

[0030] As shown in Figures 5 to 7 The bottom plate spring 21 is provided with a first through hole 211, the action plate spring 22 is provided with a second through hole 221 corresponding to the first through hole 211, and the quick-release positioning piece 23 is arranged through the first through hole 211 and the second through hole 221. The quick-release positioning piece 23 can be a bolt piece, which provides positioning function for the bottom plate spring 21 and the action plate spring 22. In addition, one end of the bottom plate spring 21 away from the first through hole 211 is provided with a hook portion 212, one end of the action plate spring 22 away from the second through hole 221 is provided with a communication hole 222, and the hook portion 212 is arranged through the communication hole 222. The communication hole 222 is specifically in the shape of a rectangle. When the bottom plate spring 21 and the plurality of action plate springs 22 are compressed, the hook portion 212 can move in the communication hole 222. The arrangement of the hook portion 212 and the communication hole 222 also provides positioning function for the bottom plate spring 21 and the action plate spring 22. The bottom plate spring 21 and the plurality of action plate springs 22 are both spring pieces with bent plates, and the number of the action plate springs 22 is preferably three.

[0031] In this embodiment, as Figures 2 to 4 As shown, there are two cover plates: a first mounting cover plate 31 and a second mounting cover plate 32. The second mounting cover plate 32 is located above the first mounting cover plate 31. The first mounting cover plate 31 has a first connecting hole 311 corresponding to the quick-release positioning piece 23, and the second mounting cover plate 32 has a second connecting hole 321 corresponding to the first connecting hole 311. Both the first connecting hole 311 and the second connecting hole 321 can be bolt holes. The quick-release positioning piece 23 is threadedly connected to the first connecting hole 311 and the second connecting hole 321 to connect the bottom leaf spring 21 and the actuating leaf spring 22 to the cover plate assembly 3.

[0032] like Figure 3 and Figure 4 As shown, the upper tube seat of the nuclear fuel assembly also includes a limiting member 4. The seat body 1 is provided with a first limiting hole 11, and the first mounting cover plate 31 is provided with a second limiting hole 312 corresponding to the first limiting hole 11. The two ends of the limiting member 4 are respectively connected to the first limiting hole 11 and the second limiting hole 312. The limiting member 4 is preferably a limiting pin, which is used to connect the seat body 1 and the first mounting cover plate 31.

[0033] The base 1 has a first mating hole 12, the first mounting cover 31 has a second mating hole 313 corresponding to the first mating hole 12, and the second mounting cover 32 has a third mating hole 323 corresponding to the second mating hole 313. Positioning pins can be installed into the first mating hole 12, the second mating hole 313, and the third mating hole 323 to complete the relative positioning between the base 1, the first mounting cover 31, and the second mounting cover 32. There are two of each of the first mating hole 12, the second mating hole 313, and the third mating hole 323, and the two first mating holes 12, the second mating hole 313, and the third mating hole 323 are arranged diagonally.

[0034] Preferably, the distance between the lower end face of the first mounting cover plate 31 and the upper end face of the second mounting cover plate 32 is 15mm to 30mm. This distance is the thickness of the cover plate assembly 3, which can be determined as follows: Considering the hydraulic forces, buoyancy, gravity, and design margins experienced by the fuel assembly during reactor operation, the required clamping force to prevent the fuel assembly from jumping during operation is calculated. Considering the irradiation relaxation of the clamping springs and the irradiation growth of the fuel assembly, the design thickness of the cover plate assembly 3 can be determined based on the clamping spring force-deformation curve, the clamping force requirement, the distance between the upper and lower core plates, and the height of the fuel assembly excluding the cover plates. The number of cover plates in the cover plate assembly 3 can be adjusted according to actual conditions, and can be two or more.

[0035] It can be understood that the above embodiments only express the preferred embodiments of the present application, which are described more specifically and in detail, but cannot be understood as a limitation to the patent scope of the present application; it should be pointed out that the above technical features can be freely combined without departing from the concept of the present application for those skilled in the art, and several modifications and improvements can be made, which all belong to the protection scope of the present application; therefore, any equivalent transformation and modification made to the patent claim scope of the present application shall belong to the coverage of the patent claim of the present application.

Claims

1. A nuclear fuel assembly upper nozzle, characterized by, The nuclear fuel assembly upper tube seat comprises a seat body (1), a plurality of quick release assemblies (2), and a cover plate assembly (3). Each quick release assembly (2) comprises a bottom plate spring (21), a plurality of action plate springs (22), and a quick release positioning piece (23). The plurality of action plate springs (22) are stacked and arranged above the bottom plate spring (21). The quick release positioning piece (23) is arranged through the bottom plate spring (21) and the plurality of action plate springs (22). The bottom plate spring (21) is abutted on the upper end surface of the seat body (1). The lower end of the quick release positioning piece (23) is clamped below the bottom plate spring (21). The upper end of the quick release positioning piece (23) is connected to the cover plate assembly (3). The cover plate assembly (3) comprises at least two cover plate pieces, and the at least two cover plate pieces are detachably connected. The distance between the at least two cover plate pieces is adjusted, so that the overall height of the nuclear fuel assembly upper tube seat is changed.

2. The nuclear fuel assembly upper nozzle according to claim 1, wherein The bottom plate spring (21) is provided with a first through hole (211). The action plate spring (22) is provided with a second through hole (221) corresponding to the first through hole (211). The quick release positioning piece (23) is arranged through the first through hole (211) and the second through hole (221).

3. The nuclear fuel assembly upper nozzle according to claim 2, wherein, The bottom plate spring (21) is provided with a hook portion (212) at one end away from the first through hole (211). The action plate spring (22) is provided with a communication hole (222) at one end away from the second through hole (221). The hook portion (212) is arranged through the communication hole (222).

4. The nuclear fuel assembly upper nozzle according to claim 1, wherein The number of cover plate pieces is two. The two cover plate pieces are a first mounting cover plate (31) and a second mounting cover plate (32). The second mounting cover plate (32) is arranged above the first mounting cover plate (31). The first mounting cover plate (31) is provided with a first connecting hole (311) corresponding to the quick release positioning piece (23). The second mounting cover plate (32) is provided with a second connecting hole (321) corresponding to the first connecting hole (311).

5. The nuclear fuel assembly upper nozzle of Claim 4 wherein, The seat body (1) is provided with a first limiting hole (11). The first mounting cover plate (31) is provided with a second limiting hole (312) corresponding to the first limiting hole (11). The two ends of the limiting piece (4) are respectively connected to the first limiting hole (11) and the second limiting hole (312).

6. The nuclear fuel assembly upper nozzle of Claim 4 wherein, The seat body (1) is provided with a first butt joint hole (12). The first mounting cover plate (31) is provided with a second butt joint hole (313) corresponding to the first butt joint hole (12). The second mounting cover plate (32) is provided with a third butt joint hole (323) corresponding to the second butt joint hole (313).

7. The nuclear fuel assembly upper nozzle of Claim 4 wherein, The distance between the lower end surface of the first mounting cover plate (31) and the upper end surface of the second mounting cover plate (32) is 15mm to 30mm.

8. The nuclear fuel assembly upper nozzle of Claim 1 wherein, The number of quick release assemblies (2) is four.

9. The nuclear fuel assembly upper nozzle of Claim 1 wherein, The number of action plate springs (22) is three.

10. The nuclear fuel assembly upper nozzle according to claim 1, wherein The bottom plate spring (21) and the plurality of action plate springs (22) are each a bent plate-shaped spring piece.

Images