CN110828000B

CN110828000B - Foreign matter prevention grid, lower pipe seat assembly and fuel assembly

Info

Publication number: CN110828000B
Application number: CN201910995308.7A
Authority: CN
Inventors: 汤阳阳; 庞铮铮; 李伟才; 禹文池; 陈威
Original assignee: China General Nuclear Power Corp; China Nuclear Power Technology Research Institute Co Ltd; CGN Power Co Ltd; Guangdong Nuclear Power Joint Venture Co Ltd
Current assignee: China General Nuclear Power Corp; China Nuclear Power Technology Research Institute Co Ltd; CGN Power Co Ltd; Guangdong Nuclear Power Joint Venture Co Ltd
Priority date: 2019-10-18
Filing date: 2019-10-18
Publication date: 2021-11-09
Anticipated expiration: 2039-10-18
Also published as: CN110828000A

Abstract

The invention discloses a foreign matter prevention grid, a lower pipe seat assembly and a fuel assembly, wherein the foreign matter prevention grid comprises a frame body, a plurality of first grid element sheets arranged in parallel at intervals, a plurality of second grid element sheets arranged in parallel at intervals and a plurality of subdivision blades; the first grid cell sheet and the second grid cell sheet are arranged in a staggered mode, and a plurality of grid cells are separated from the frame body; the subdivision blade is arranged at the joint of the first grid element sheet and the second grid element sheet and is encircled between the first grid element sheet and the second grid element sheet. The foreign matter prevention grid is formed by matching grid element sheets in a staggered mode, blades in a subdivided mode and the like, fluid flowing to the lower pipe seat can be divided, and the foreign matter prevention grid plays a role in preventing foreign matters while ensuring the circulation of the fluid. Meanwhile, the thickness of the grid element is small, the resistance to fluid is low, the pressure drop of the foreign matter preventing plate can be reduced to a large extent, and the hydraulic performance of the lower pipe seat assembly is improved.

Description

Foreign matter prevention grid, lower pipe seat assembly and fuel assembly

Technical Field

The invention relates to the technical field of nuclear fuel assemblies, in particular to a foreign matter prevention grid, a lower pipe seat assembly and a fuel assembly.

Background

In the present anti-foreign body design of the bottom nozzle, there are two types of anti-foreign body modes which are generally adopted: one is assembling foreign matter preventing board, which is adhered to the upper and lower surfaces of the pipe seat and has fine flow holes corresponding to the water flow holes; the other one is that the lower pipe seat connecting plate adopts the design of special-shaped rib plates, is designed into a blade structure with curved surface protrusions, and is formed by combining the pipe seat connecting plate in a transverse and vertical cross mode, and the flow holes form curved flow channels and have the function of preventing foreign matters.

CN203070777U discloses a lower tube seat partition plate, which is composed of two plates, wherein the two plates are provided with flow holes of different shapes, and the positions of the holes are staggered to form division of the holes when the two plates are superposed. The two layers of plates form a lower tube seat connecting plate and play a role in preventing foreign matters. However, the foreign matter prevention structure can reduce the liquid flow area of the lower pipe seat, simultaneously form larger pressure drop and reduce the hydraulic performance of the pipe seat.

Disclosure of Invention

The invention aims to provide a foreign matter prevention grid for reducing pressure drop and improving hydraulic performance of a pipe seat, a lower pipe seat assembly and a fuel assembly with the foreign matter prevention grid.

The technical scheme adopted by the invention for solving the technical problems is as follows: the foreign matter prevention grid comprises a frame body, a plurality of first grid element pieces arranged in parallel at intervals, a plurality of second grid element pieces arranged in parallel at intervals and a plurality of subdivision blades, wherein the first grid element pieces and the second grid element pieces are arranged in parallel at intervals; the first grid cell sheet and the second grid cell sheet are arranged in a staggered mode, and a plurality of grid cells are separated from the frame body;

the subdivision blade is arranged at the joint of the first grid element sheet and the second grid element sheet and is encircled between the first grid element sheet and the second grid element sheet.

Preferably, the plurality of cells comprises a plurality of first cells corresponding to the fuel rods and a plurality of second cells corresponding to the guide tubes and the instrument tubes; the second cells are distributed among the first cells according to the arrangement of the guide tubes and the instrument tubes in the fuel assembly.

Preferably, the first gate cell sheet and the second gate cell sheet are provided with arc parts protruding to the outer side of the second gate cell at positions corresponding to the second gate cell.

Preferably, the plurality of subdivided vanes comprises a plurality of first subdivided vanes having a closed annular shape in cross section and a plurality of second subdivided vanes having an open annular shape in cross section;

at the joint of the first grid cell sheet and the second grid cell sheet, the first subdivision blade is divided into four blade sections which are respectively positioned in the four connected first grid cells; the opening of the second subdivided blade faces one of the second cells, and the second subdivided blade is divided into three blade segments and is respectively positioned in the three first cells connected with the second cells.

Preferably, the plurality of first subdivided blades are one or more of cylindrical subdivided blades and square cylindrical subdivided blades.

Preferably, one end of the subdivided blade is provided with a plurality of first slots which are uniformly distributed at intervals along the circumferential direction and axially extend, and the corresponding positions of the first grid element sheet and the second grid element sheet are also respectively provided with a second slot; the subdivided vanes are adjoined between the first and second cell pieces at the interface with the first and second slots interfacing.

Preferably, the foreign matter prevention grid further comprises a plurality of connecting sheets provided with central through holes; the connecting pieces are arranged below the second grid cells one by one.

Preferably, the periphery of the connecting piece is also provided with a plurality of connecting lugs which are distributed at intervals; the connecting lug is bent upwards and connected on the first grid element sheet and the second grid element sheet in a matched mode.

The invention also provides a lower pipe seat assembly, which comprises a lower pipe seat and the foreign matter prevention grid arranged on the lower pipe seat; and the subdivision blades of the foreign matter prevention grid are correspondingly arranged above the water flowing holes of the lower pipe seat.

Preferably, the lower tube base is provided with a plurality of protrusions arranged according to the arrangement position of the fuel rods; the protrusions penetrate into the first cells of the foreign matter prevention grid one by one.

The invention also provides a fuel assembly which comprises the lower pipe seat assembly.

The foreign matter prevention grid is formed by matching grid element sheets in a staggered mode, blades in a subdivided mode and the like, fluid flowing to the lower pipe seat can be divided, and the foreign matter prevention grid plays a role in preventing foreign matters while ensuring the circulation of the fluid. Meanwhile, the thickness of the grid element is small, the resistance to fluid is low, the pressure drop of the foreign matter preventing plate can be reduced to a large extent, and the hydraulic performance of the lower pipe seat assembly is improved.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic view of a foreign matter prevention grid according to an embodiment of the present invention;

fig. 2 is an enlarged view illustrating a portion of the structure of the foreign matter prevention grill of fig. 1;

FIG. 3 is a schematic view showing a structure of a first subdivided blade in the foreign matter prevention grid according to the embodiment of the present invention;

FIG. 4 is another schematic view of the first subdivided blades of the foreign matter prevention grid according to the embodiment of the present invention;

fig. 5 is a partial structural view of a first grid element sheet or a second grid element sheet in the foreign matter prevention grid according to an embodiment of the invention;

FIG. 6 is a schematic structural view of a connecting sheet in the foreign matter prevention grid according to an embodiment of the present invention;

FIG. 7 is a schematic structural view of a lower seat assembly in accordance with one embodiment of the present invention;

FIG. 8 is a schematic view of the lower nozzle assembly according to one embodiment of the present invention;

fig. 9 is a schematic structural view of a lower header assembly according to another embodiment of the present invention.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

As shown in fig. 1 and 2, the foreign matter prevention grid 1 according to an embodiment of the present invention is used for a bottom nozzle of a fuel assembly, and the foreign matter prevention grid 1 may include a frame 30, a plurality of first grid elements 10 arranged in parallel at intervals in the frame 30, a plurality of second grid elements 20 arranged in parallel at intervals, and a plurality of fine-divided blades 40.

The frame 30 is shaped to correspond to the outer periphery of the lower pipe seat, and may have a square, rectangular, regular pentagonal, or regular hexagonal shape. The first and

second cell sheets

10 and 20 are arranged in a staggered manner, and a plurality of cells 50 are partitioned in the frame 30. The two end portions of the first grid element piece 10 and the second grid element piece 20 may be fixedly connected to the inner wall of the frame 30 by welding or the like. The first grid element sheet 10 and the second grid element sheet 20 can be arranged in the frame 30 in a manner of being inserted in a horizontal and vertical manner and fixed in a welding manner.

The subdividing vanes 40 are arranged at the junctions of the first grid element pieces 10 and the second grid element pieces 20 and are enclosed between the first grid element pieces 10 and the second grid element pieces 20, so that subdivided water flow holes (four subdividing water flow holes enclosed by the crisscross shape of the subdividing vanes 40 at the junctions in fig. 1) are defined between the subdividing vanes 40 and the junctions.

On the lower tube seat, the joint of the first grid element sheet 10 and the second grid element sheet 20 corresponds to the upper part of the water flow hole of the lower tube seat, and the water flow hole of the lower tube seat is divided by the arrangement of the subdivision blades 40 at the joint, so that the liquid circulation is ensured and the effect of preventing foreign matters is achieved. The first grid element sheet 10 and the second grid element sheet 20 are both strip-shaped sheets, are small in thickness and low in fluid resistance, can reduce the pressure drop of the foreign matter prevention grid 1 to a large extent, and improve the hydraulic performance of the lower pipe seat.

The cells 50 are arranged in multiple rows and columns in the frame 30, and further include a plurality of first cells 51 corresponding to the fuel rods, and a plurality of second cells 52 corresponding to the guide tubes and instrumentation tubes. A plurality of second cells 51 are dispersed between the first cells 52 in the arrangement of the pilot and instrumentation tubes in the fuel assembly.

As shown in fig. 2, in order to fit the end plugs of the guide tube and the instrument tube, the first grid piece 10 and the second grid piece 20 are respectively provided with

arc portions

11 and 21 protruding to the outside of the second grid 52 at positions corresponding to the second grid 52, that is, the

arc portions

11 and 21 are provided on the four walls of the second grid 52. The provision of the

circular arcs

11, 21 is such that the space in the second cell 52 will be slightly larger than the space in the first cell 51, facilitating the end-plug fit therein.

The plurality of subdivided vanes 40 may include a plurality of first subdivided vanes 41 having a closed annular shape in cross section and a plurality of second subdivided vanes 42 having an open annular shape in cross section, corresponding to the cells 50.

At the joint of the first grid element sheet 10 and the second grid element sheet 20, the first subdivision blade 41 is divided into four blade segments which are connected in the circumferential direction and are respectively positioned in four first grid elements 51 which are connected; the second subdivision vanes 42 open toward a second cell 52, and the second subdivision vanes 42 are divided into three circumferentially adjacent vane segments and are located in three first cells 51 adjacent to the second cell 52, respectively.

The first subdivided blades 41 have a cylindrical structure as a whole. In an alternative embodiment, the first subdivided vanes 41 may be cylindrical subdivided vanes as shown in FIG. 3; in another alternative embodiment, the first sub-divided blade 41 may be a square cylinder type sub-divided blade as shown in fig. 4. In the foreign matter prevention grille, the plurality of first subdividing blades 41 may also include a cylindrical subdividing blade and a square cylindrical subdividing blade.

Similarly, the second subdivision vanes 42 may be one or more of cylindrical subdivision vanes with one side open and square cylindrical subdivision vanes with one side open.

In order to facilitate the installation and connection of the subdividing blades 40 at the junctions of the first cell piece 10 and the second cell piece 20, the subdividing blades 40 may be interposed between the first cell piece 10 and the second cell piece 20 in a plugging manner. For example, a plurality of first slits 401 are provided at intervals in the subdividing blade 40, a second slit 402 is provided at a position corresponding to the first grid element piece 10 and the second grid element piece 20, and the subdividing blade 40 is enclosed between the first grid element piece 10 and the second grid element piece 20 with the first slit 401 abutting against the second slit 402.

The opening of the first slot 401 and/or the second slot 402 may further be provided with a guide opening (flared shape) for guiding the butt joint of the two slots.

As shown in fig. 3 to 5, the first subdividing blade 41 is provided with a first slit 401 at a position corresponding to the first grid element piece 10 and the second grid element piece 20, and the first slit 402 is also provided at a position corresponding to the first grid element piece 10 and the second grid element piece 20. When the first sub-divided vane 41 is installed, the first slit 401 is inserted into the second slit 402, and the first slit 401 is fitted to the opposite surfaces of the first grid element sheet 10 (the second grid element sheet 20) through the second slit 402, so that the whole first sub-divided vane 41 is inserted at the intersection of the first grid element sheet 10 and the second grid element sheet 20, and the top is flush with or lower than the top of the first grid element sheet 10 and the second grid element sheet 20.

Similarly, the second sub-divided vane 42 is inserted into the intersection of the first grid element 10 and the second grid element 20 through a first slot 401 (refer to the slot shown in fig. 3). In contrast, the first subdividing blade 41 is provided with four first slits 401, which are divided into four blade segments and located in the four first cells 51 that are connected after passing through the junction of the first cell sheet 10 and the second cell sheet 20. The second sub-divided vane 42 is provided with three first slits 401, and after passing through the junction of the first grid element sheet 10 and the second grid element sheet 20, the second sub-divided vane 42 is divided into three vane segments and respectively located in the three connected first grid elements 51, and the opening side of the second sub-divided vane 42 faces the second grid element 52 and does not extend into the second grid element 52.

Further, the foreign matter prevention grill 1 of the present invention may further include a plurality of connection pieces 60 provided with a central through hole 61. A plurality of connecting pads 60 are disposed one below each of the plurality of second cells 52.

The connecting piece 60 may be of circular configuration as shown in figure 6. The periphery of the connecting piece 60 is further provided with a plurality of connecting lugs 62 distributed at intervals, and the connecting lugs 62 are connected to the first grid element piece 10 and the second grid element piece 20 in an upward bending and matching manner.

Specifically, as shown in fig. 2 and 6, the connecting lugs 62 of the connecting pieces 60 are respectively fitted and fixed by spot welding or the like to the side faces of the first cell piece 10 and the second cell piece 20 alternately formed into the second cell 52, which is the side face facing away from the second cell 52, below the second cell 52, so that the connecting lugs 62 do not fall into the second cell 52 but into the first cell 51 adjacent to the second cell 52. More specifically, the engaging lug 62 is fixed to the side of the

circular arc portion

11, 21 away from the second cell 52.

The connecting piece 60 is helpful to fix the foreign-matter-preventing grid 1 on the lower tube seat through the matching of the end plugs and the screws, and the welding problem of dissimilar metals can be overcome. In the foreign matter prevention grid without the connecting pieces 60, the foreign matter prevention grid 1 may be fixed to the bottom base by soldering the bottom surfaces of the first grid element pieces 10 and the second grid element pieces 20 to the bottom base. Therefore, the foreign matter prevention grid 1 of the present invention may be fixed to the lower socket by mechanical fixing or soldering.

As shown in fig. 7 and 8, the lower socket assembly according to an embodiment of the present invention includes the above-mentioned foreign matter prevention grid 1 and the lower socket 2. The foreign matter prevention grid 1 is arranged on the lower pipe seat 2 and plays a certain role in blocking foreign matters in fluid flowing to the lower pipe seat 2.

In this embodiment, the upper surface of the lower pipe base 2 is a plane, the lower pipe base 2 is provided with a plurality of water flow holes 201 which are arranged in an array and run through the upper surface and the lower surface of the lower pipe base 2, the subdividing blades 40 of the foreign matter prevention grid 1 are in one-to-one correspondence with the water flow holes 201, and the inlet ends of the water flow holes 201 are subdivided to play a role of preventing foreign matters.

Referring to fig. 1, 2 and 7, the method for assembling the foreign matter prevention grid 1 to the bottom nozzle 2 is as follows: the foreign matter prevention grid 1 is placed on the lower pipe seat 2, the second grid cell 52 corresponds to the guide pipe installation position 202 of the lower pipe seat 2, an end plug (guide pipe end plug) 203 is matched into the second grid cell 52 and placed on the connecting sheet 60, a screw 204 penetrates through the connecting sheet 60 and the end plug 203 from the lower part of the lower pipe seat 2, the external thread of the screw 204 is matched with the internal thread of the end plug 203 to enable the external thread and the internal thread to be fastened into a whole, so that the connecting sheet 60 is fixed on the lower pipe seat 2, and the foreign matter prevention grid 1 is fixed on the lower pipe seat 2.

As shown in fig. 9, a lower nozzle assembly according to another embodiment of the present invention includes the above-mentioned foreign matter prevention grill 1 and the lower nozzle 3. The foreign matter prevention grid 1 is arranged on the lower pipe seat 3 and plays a certain role in blocking foreign matters in fluid flowing to the lower pipe seat 3.

Referring to fig. 1 and 9, in the present embodiment, the lower pipe base 3 is provided with a plurality of water flow holes (not shown) arranged in an array and penetrating through the upper and lower surfaces of the lower pipe base 3 and a plurality of protrusions 301, the fine-divided blades 40 of the foreign matter prevention grid 1 are in one-to-one correspondence with the water flow holes, and the inlet ends of the water flow holes are fine-divided to play a role of preventing foreign matters.

The plurality of protrusions 301 are arranged in the fuel rod array position and between the water flow holes. The protrusions 301 penetrate one by one into the first cells 51 of the foreign matter prevention grid 1. In the fuel assembly, the central axis of each fuel rod coincides with the central axis of the protrusion 301.

The lower tube base 3 in this embodiment is a protruded lower tube base, and the specific structure can refer to CN 108010590A.

The lower pipe seat assembly has better hydraulic performance by matching the foreign matter preventing grid with the lower pipe seat, can reduce pressure drop and increase the uniformity of a flow field at an outlet position.

The fuel assembly of the invention comprises the lower pipe seat assembly of any one of the embodiments.

The fuel assembly also comprises an upper pipe seat, a plurality of location grids, a plurality of guide pipes, a plurality of fuel rods and the like. The upper pipe seat and the lower pipe seat assembly are arranged oppositely, the plurality of positioning grillworks are arranged between the upper pipe seat and the lower pipe seat assembly at intervals along the axial direction of the fuel assembly, the guide pipe penetrates through the positioning grillworks and is arranged between the upper pipe seat and the lower pipe seat assembly, and the fuel rod penetrates through and is clamped between the positioning grillworks.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. The foreign matter prevention grid is used on a lower tube seat of a fuel assembly and comprises a frame body, a plurality of first grid element pieces which are arranged in parallel at intervals, a plurality of second grid element pieces which are arranged in parallel at intervals and a plurality of subdivision blades; the first grid cell sheet and the second grid cell sheet are arranged in a staggered mode, and a plurality of grid cells are separated from the frame body;

the subdivision blade is arranged at the joint of the first grid element sheet and the second grid element sheet, and the slot is embedded between the first grid element sheet and the second grid element sheet; the junction of the first grid element sheet and the second grid element sheet corresponds to the upper part of the water flow hole of the lower pipe seat, and a plurality of subdivided water flow holes are defined between the subdivided blades and the junction.

2. The foreign matter prevention grid according to claim 1, wherein the plurality of cells includes a plurality of first cells corresponding to fuel rods, and a plurality of second cells corresponding to guide tubes and instrumentation tubes; the second cells are distributed among the first cells according to the arrangement of the guide tubes and the instrument tubes in the fuel assembly.

3. The foreign matter prevention grid according to claim 2, wherein the first cell piece and the second cell piece are provided with a circular arc portion protruding to the outside of the second cell at a position corresponding to the second cell.

4. The foreign matter prevention grid according to claim 2, wherein the plurality of divided blades includes a plurality of first divided blades having a closed ring shape in cross section and a plurality of second divided blades having an open ring shape in cross section;

5. The foreign-substance-preventing grid according to claim 4, wherein the plurality of first subdivided blades are one or more of cylindrical subdivided blades and square-cylindrical subdivided blades.

6. The foreign matter prevention grid according to claim 2, wherein one end of the subdivided blade is provided with a plurality of first slits which are uniformly distributed at intervals along the circumferential direction and axially extend, and the corresponding positions of the first grid element sheet and the second grid element sheet are also respectively provided with second slits; the subdivided vanes are adjoined between the first and second cell pieces at the interface with the first and second slots interfacing.

7. The foreign matter prevention grid according to any one of claims 2 to 6, further comprising a plurality of connecting pieces provided with a central through hole; the connecting pieces are arranged below the second grid cells one by one.

8. The foreign matter prevention grid according to claim 7, wherein the connecting sheet is further provided with a plurality of connecting lugs at intervals on the periphery; the connecting lug is bent upwards and connected on the first grid element sheet and the second grid element sheet in a matched mode.

9. A lower nozzle assembly comprising a lower nozzle and the foreign matter prevention grid of any one of claims 1 to 8 provided on the lower nozzle; and the subdivision blades of the foreign matter prevention grid are correspondingly arranged above the water flowing holes of the lower pipe seat.

10. The bottom nozzle assembly of claim 9, wherein the bottom nozzle includes a plurality of protrusions arranged in the fuel rod array; the protrusions penetrate into the first cells of the foreign matter prevention grid one by one.

11. A fuel assembly comprising the lower header assembly of claim 9 or 10.