Lower pipe seat of fuel assembly

Abstract

The invention discloses a lower pipe seat of a fuel assembly. The lower pipe seat comprises a seat body and a base, the seat body comprises a tube seat plate and a plurality of supporting legs arranged below the tube seat plate and used for supporting the tube seat plate, the base comprises a base body and a plurality of connecting parts arranged on the base body, the connecting parts and the supporting legs are arranged correspondingly, and each connecting part is provided with a clamping groove corresponding to the corresponding supporting leg. According to the fuel assembly lower pipe base, the base is additionally arranged below the base body to increase the height of the fuel assembly in the free state, the compression amount of a fuel assembly pressing system is increased to compensate for the insufficient pressing force, the height of the fuel assembly in the free state can be adjusted by adjusting the height of the base, and therefore the compression amount of the fuel assembly pressing system is adjusted; and the pressing force requirements of fuel assemblies at different positions in the reactor core can be met. And meanwhile, the initial compression amount of the compression spring of the full-reactor-core fuel assembly is reduced, and the bending risk of the fuel assembly caused by too large pressing force of the fuel assembly can be effectively reduced.

Description

Technical Field

[0001] The invention relates to the field of reactor nuclear fuel, in particular to a lower tube seat of a fuel assembly. Background Art

[0002] In existing pressurized water reactors, in order to ensure the compression of fuel assemblies under different irradiation growth conditions, the initial compression of the compression spring needs to be conservative to consider the compression of the fuel assembly with the smallest height (i.e., the new fuel assembly). Therefore, the compression force on the fuel assembly at the end of its life is too conservative, which easily leads to the problem of fuel assembly bending. The current solution cannot adjust the compression of the fuel assembly compression system. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a lower tube seat of a fuel assembly.

[0004] The technical solution adopted by the present invention to solve the technical problem is: constructing a lower tube seat of a fuel assembly, which includes a seat body and a base;

[0005] The seat body comprises a tube seat plate and a plurality of legs arranged below the tube seat plate and used for supporting the tube seat plate;

[0006] The base includes a base body and a plurality of connecting parts arranged on the base body, the connecting parts are arranged corresponding to the supporting legs, and each of the connecting parts is provided with a clamping groove corresponding to the supporting leg.

[0007] In some embodiments, the number of the legs is four, and the four legs are separately located at the four corners of the seat body;

[0008] The number of the connecting parts is four, and the four connecting parts are separately located at four corners of the base.

[0009] In some embodiments, two connecting parts at diagonal positions of the base are provided with first positioning holes, and two supporting legs at diagonal positions of the base are provided with second positioning holes corresponding to the first positioning holes.

[0010] In some embodiments, the depth of the positioning groove is 1 mm to 2 mm.

[0011] In some embodiments, the tube seat plate and the support leg are an integral structure; or the tube seat plate and the support leg are welded and connected.

[0012] In some embodiments, the base and the connecting portion are an integral structure; or the base and the connecting portion are welded and connected.

[0013] In some embodiments, the length of the base is consistent with the length of the tube base plate, and the width of the base is consistent with the width of the tube base plate.

[0014] In some embodiments, the tube base plate is provided with a plurality of water flow holes.

[0015] In some embodiments, the legs are provided with chamfered structures.

[0016] In some embodiments, the base is made of stainless steel.

[0017] The implementation of the present invention has the following beneficial effects: the lower tube seat of the fuel assembly increases the height of the fuel assembly in the free state by adding a base under the seat body, increases the compression of the fuel assembly clamping system to compensate for the lack of clamping force, and can adjust the height of the fuel assembly in the free state by adjusting the height of the base, thereby adjusting the compression of the fuel assembly clamping system to meet the clamping force requirements of the fuel assemblies at different positions inside the core. At the same time, the initial compression of the clamping spring of the fuel assembly of the entire core is reduced, which can effectively reduce the risk of fuel assembly bending caused by excessive fuel assembly clamping force. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show 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 be obtained based on these drawings without creative work. In the drawings:

[0019] Figure 1 It is a schematic diagram of the three-dimensional structure of the lower tube seat of the fuel assembly in some embodiments of the present invention;

[0020] Figure 2 is a schematic diagram of a three-dimensional structure of a base in some embodiments of the present invention;

[0021] Figure 3 A top view of the structure of a base in some embodiments of the present invention;

[0022] Figure 4 It is a schematic diagram of the three-dimensional structure of the seat body in some embodiments of the present invention;

[0023] Figure 5 This is a schematic diagram of the application of the lower tube seat of the fuel assembly in some embodiments of the present invention in the fuel assembly. DETAILED DESCRIPTION

[0024] 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. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the device or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0025] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; 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. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. can explicitly or implicitly include one or more of the features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0026] See also Figures 1 to 5 , is a fuel assembly lower tube seat in some embodiments of the present invention, which includes a seat body 1 and a base 2. The seat body 1 includes a tube seat plate 11 and a plurality of legs 12 arranged below the tube seat plate 11 and used to support the tube seat plate 11, and the base 2 includes a base 21 and a plurality of connecting parts 22 arranged on the base 21, and the connecting parts 22 are arranged corresponding to the supporting legs 12, and each connecting part 22 is provided with a clamping groove 221 corresponding to the supporting leg 12.

[0027] It can be understood that in a pressurized water reactor, the lower tube seat of the fuel assembly is located on the lower core plate, and the upper core plate is pressed on the fuel assembly clamping system. Since the height of the fuel assembly in the free state is greater than the height of the core cavity, the clamping system is always in a compressed state. During operation, due to different neutron injections in different areas, the skeleton growth of fuel assemblies at different positions is different, resulting in differences in the compression of the clamping system, resulting in large differences in the clamping force. Since the growth of the fuel assembly after irradiation is greater than that of the newly added fuel assembly, the height of the fuel assembly in the free state is increased by adding a base 2 under the seat body 1, and the compression of the fuel assembly clamping system is increased to compensate for the lack of clamping force. The height of the fuel assembly in the free state can be adjusted by adjusting the height of the base 2, thereby adjusting the compression of the fuel assembly clamping system, which can meet the clamping force requirements of fuel assemblies at different positions inside the core. At the same time, reducing the initial compression of the full core fuel assembly clamping spring can effectively reduce the risk of fuel assembly bending caused by excessive fuel assembly clamping force. It can be applied to the existing reactor refueling, taking into account the positions of new fuel assemblies in different refueling cycles, and running a certain cycle, and then removing the base 2.

[0028] like Figures 2 to 4 As shown, there are four legs 12, which are separately located at the four corners of the base 1. There are four connecting parts 22, which are separately located at the four corners of the base 21. The legs 12 and the connecting parts 22 are arranged correspondingly and in the same number, and the four legs 12 are symmetrically arranged, and the four connecting parts 22 are also symmetrically arranged.

[0029] like Figure 3 and Figure 4 As shown, two connecting parts 22 at diagonal positions of the base 2 are provided with first positioning holes 222, and two legs 12 at diagonal positions of the base body 1 are provided with second positioning holes 121 corresponding to the first positioning holes 222. Positioning pins can be installed in the first positioning holes 222 and the second positioning holes 121 to achieve radial positioning between the base body 1 and the base 2 and the lower core plate.

[0030] In addition, the depth of the positioning groove 221 is 1mm to 2mm to ensure the stability of the connection between the leg 12 and the connecting portion 22. The positioning groove 221 can guide and protect the leg 12 to a certain extent. The leg 12 is provided with a chamfered structure 122 to facilitate the leg 12 to slide into the positioning groove 221 to achieve positioning and fixing.

[0031] The base plate 11 and the legs 12 are an integral structure; or the base plate 11 and the legs 12 are welded to increase the connection strength between the two. The base 21 and the connecting portion 22 are an integral structure; or the base 21 and the connecting portion 22 are welded to increase the connection strength between the two.

[0032] The length of the base 21 is consistent with the length of the tube seat plate 11, and the width of the base 21 is consistent with the width of the tube seat plate 11. That is, the dimensions of the base 1 and the base 2 are kept consistent to ensure the stability of the cooperation between the two. In addition, by adjusting the overall height of the base 2, the overall clamping force of the clamping system can be reduced by 250N to 500N. The tube seat plate 11 is also provided with a plurality of water holes 111, which can allow coolant to pass through.

[0033] Preferably, the base 2 is made of stainless steel, which has good rigidity and hardness, good corrosion resistance, and can ensure the stability of the base 2 in use.

[0034] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the scope covered by the claims of the present invention.

Claims

1. A fuel assembly lower tube socket, characterized in that: It comprises a seat body (1) and a base (2); The seat body (1) comprises a tube seat plate (11) and a plurality of legs (12) arranged below the tube seat plate (11) and used for supporting the tube seat plate (11); The base (2) comprises a base (21) and a plurality of connecting parts (22) arranged on the base (21); the connecting parts (22) are arranged corresponding to the supporting legs (12), and each of the connecting parts (22) is provided with a locking groove (221) corresponding to the supporting leg (12).

2. The fuel assembly lower tube socket according to claim 1, characterized in that: The number of the supporting legs (12) is four, and the four supporting legs (12) are separately located at the four corners of the seat body (1); The number of the connecting parts (22) is four, and the four connecting parts (22) are separately located at the four corners of the base (21).

3. The fuel assembly lower tube socket according to claim 1, characterized in that: Two connecting parts (22) at diagonal positions of the base (2) are provided with first positioning holes (222), and two supporting legs (12) at diagonal positions of the base body (1) are provided with second positioning holes (121) corresponding to the first positioning holes (222).

4. The fuel assembly lower tube socket according to claim 1, characterized in that: The depth of the locking groove (221) is 1 mm to 2 mm.

5. The fuel assembly lower tube socket according to claim 1, characterized in that: The tube seat plate (11) and the support leg (12) are an integral structure; or the tube seat plate (11) and the support leg (12) are connected by welding.

6. The fuel assembly lower tube socket according to claim 1, characterized in that: The base (21) and the connecting portion (22) are an integral structure; or the base (21) and the connecting portion (22) are connected by welding.

7. The fuel assembly lower tube socket according to claim 1, characterized in that: The length of the base (21) is consistent with the length of the tube base plate (11), and the width of the base (21) is consistent with the width of the tube base plate (11).

8. The fuel assembly lower tube socket according to claim 1, characterized in that: The tube seat plate (11) is provided with a plurality of water flow holes (111).

9. The fuel assembly lower tube socket according to claim 1, characterized in that: The supporting leg (12) is provided with a chamfered structure (122).

10. The fuel assembly lower tube socket according to claim 1, characterized in that: The base (2) is made of stainless steel.

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