Fuel assembly and its lower tube socket

Abstract

The present invention discloses a fuel assembly and a lower tube seat thereof, wherein the lower tube seat comprises a connecting plate, a plurality of supporting legs and a supporting structure; a plurality of the supporting legs are connected at intervals below the connecting plate, and the supporting structure is connected below the connecting plate between the plurality of supporting legs. The present invention arranges a supporting structure on the connecting plate, thereby reducing the stress of the lower tube seat and the fluid pressure loss coefficient in the lower tube seat area, and improving the dimensional stability of the lower tube seat; by reducing the stress level of the lower tube seat connecting plate, space is reserved for improving hydraulic performance, so that the flow field of the fuel rod bundle area above the lower tube seat is more uniform, which is conducive to reducing the flow-induced vibration level of the lower end of the fuel rod.

Description

Technical Field

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

[0002] The existing lower tube seat bears all the loads of the fuel assembly and transfers it to the connecting plate through the guide tube connection, and then to the four supporting legs through the connecting plate, and then to the lower core plate, resulting in large local stress at the connecting plate and high strength requirements.

[0003] In addition, in the existing lower tube seat, after the fluid (coolant) enters the lower tube seat chamber from the four injection holes of the lower core plate, the four fluids converge at the lower part of the lower tube seat and undergo a sudden expansion and contraction process, resulting in a large fluid pressure loss coefficient. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a lower tube seat of a fuel assembly which reduces the stress of the lower tube seat, reduces the fluid pressure loss in the lower tube seat area, and improves the dimensional stability of the lower tube seat, and a fuel assembly having the lower tube seat.

[0005] The technical solution adopted by the present invention to solve the technical problem is: to provide a lower tube seat of a fuel assembly, comprising a connecting plate, a plurality of supporting legs and a supporting structure; a plurality of the supporting legs are connected below the connecting plate at intervals, and the supporting structure is connected below the connecting plate between the plurality of supporting legs;

[0006] The support structure is a continuous cross-shaped structure or a discontinuous cross-shaped structure. The support structure (30) divides the space below the connecting plate (10) into four spaced or connected chambers, and the four chambers respectively correspond to the four inlets of the lower core plate for spraying coolant.

[0007] Preferably, the support structure comprises one or more support members.

[0008] Preferably, the plurality of support members are connected or dispersed at intervals.

[0009] Preferably, the longitudinal cross-sectional shape of the support member is at least one of rectangular, trapezoidal, conical and irregular.

[0010] Preferably, the cross-sectional shape of the support member is at least one of rectangular, cross-shaped, circular and irregular.

[0011] Preferably, the bottom surface of the support structure is flush with the bottom surfaces of the support legs.

[0012] Preferably, the connecting plate is provided with a plurality of through holes penetrating the upper and lower surfaces of the connecting plate; and the supporting structure is arranged below the connecting plate to avoid the through holes.

[0013] Preferably, the supporting structure is located in the middle of the connecting plate and extends toward the periphery of the connecting plate.

[0014] Preferably, the lower tube seat further comprises a skirt; the skirt is connected below the connecting plate and between the adjacent supporting legs.

[0015] The present invention also provides a fuel assembly, comprising the lower tube seat described in any one of the above items.

[0016] The beneficial effects of the present invention are as follows: a support structure is arranged on the connecting plate, which reduces the stress of the lower tube seat and the fluid pressure loss coefficient in the lower tube seat area, while improving the dimensional stability of the lower tube seat; by reducing the stress level of the lower tube seat connecting plate, space is reserved for improving the hydraulic performance, so that the flow field in the fuel rod bundle area above the lower tube seat is more uniform, which is beneficial to reducing the flow-induced vibration level of the lower end of the fuel rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0018] Figure 1 is a schematic structural diagram of a lower tube seat according to a first embodiment of the present invention;

[0019] Figure 2 yes Figure 1 The schematic diagram of the cross-sectional structure of the lower tube seat along the AA line is shown;

[0020] Figure 3 is a schematic structural diagram of a lower tube seat according to a second embodiment of the present invention;

[0021] Figure 4 is a schematic structural diagram of a lower tube base according to a third embodiment of the present invention;

[0022] Figure 5 yes Figure 4 The schematic diagram of the cross-sectional structure of the lower tube seat along the BB line is shown;

[0023] Figure 6 2 is a schematic cross-sectional structural diagram of a lower tube seat according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0025] like Figure 1 , 2As shown, the lower tube base of the fuel assembly according to the first embodiment of the present invention may include a connection plate 10, a plurality of support legs 20 and a support structure 30. The plurality of support legs 20 are connected below the connection plate 10 at intervals, and the support structure 30 is connected below the connection plate 10 between the plurality of support legs 20.

[0026] The lower tube seat is provided with a support structure 30 so that the load borne by the lower tube seat can be transmitted to the lower core plate through the support structure 30 in addition to being transmitted through the support legs 20, thereby solving the problem of local stress concentration, reducing the stress level of the lower tube seat connecting plate 10, and improving the overall strength of the lower tube seat.

[0027] The support structure 30 is in a cross shape as a whole and is located in the middle of the connecting plate 10 and extends toward the periphery of the connecting plate 10 .

[0028] Typically, the lower tube seat includes four support legs 20, which are respectively located at four diagonal positions of the connecting plate 10. The support structure 30 is located below the middle of the connecting plate 10 and extends between every two adjacent support legs 20, playing the same supporting role as the support legs 20.

[0029] The bottom surface of the support structure 30 is flush with the bottom surface of the support leg 20 .

[0030] In this embodiment, the support structure 30 is a continuous cross-shaped structure, which divides the space below the connecting plate 10 into four chambers below the connecting plate 10. The four chambers can be directly opposite to the four inlets at the inlet of the lower core plate, and the flow distribution uniformity at the inlet of the lower tube seat can be improved by preventing the ineffective flow distribution of the coolant between the chambers, and the pressure loss coefficient of the lower tube seat can be reduced by preventing the ineffective turbulence of the coolant between the chambers.

[0031] The connecting plate 10 is provided with a plurality of through holes 11 penetrating the upper and lower surfaces of the connecting plate 10. In the fuel assembly, a portion of the through holes 11 is used for inserting and positioning the guide tubes, and a portion is used for longitudinal circulation of fluids such as coolants. The support structure 30 is located below the connecting plate 10 and avoids the through holes 11.

[0032] It can be understood that the support structure 30 in this embodiment may include one or more support members 31. For one support member 31, the whole is in a cross shape (laterally); for multiple support members 31, they are connected to form a cross-shaped structure.

[0033] The longitudinal cross section of the support member 31 can be in various shapes, such as at least one of a rectangle, a trapezoid, a cone and a special shape. The transverse cross section of the support member 31 can also be in various shapes, such as at least one of a rectangle, a cross, a circle and a special shape.

[0034] Another example Figure 1 As shown, in this embodiment, the longitudinal cross-section of the support member 31 is rectangular.

[0035] like Figure 3 As shown, the lower tube base of the fuel assembly according to the second embodiment of the present invention comprises a connecting plate 10, a plurality of supporting legs 20 and a supporting structure 30. The plurality of supporting legs 20 are connected below the connecting plate 10 at intervals, and the supporting structure 30 is connected below the connecting plate 10 between the plurality of supporting legs 20.

[0036] The present embodiment is different from the first embodiment in that the longitudinal cross section of the support member 31 of the support structure 30 is trapezoidal.

[0037] It can be understood that the trapezoid can be Figure 3 The regular trapezoid shown can also be an inverted trapezoid.

[0038] like Figure 4 , 5 As shown, the lower tube base of the fuel assembly according to the third embodiment of the present invention comprises a connecting plate 10, a plurality of supporting legs 20 and a supporting structure 30. The plurality of supporting legs 20 are connected below the connecting plate 10 at intervals, and the supporting structure 30 is connected below the connecting plate 10 between the plurality of supporting legs 20.

[0039] In this embodiment, the support structure 30 is a discontinuous cross-shaped structure.

[0040] Specifically, the support structure 30 includes a plurality of support members 31, which are dispersedly arranged along a cross below the connecting plate 10. At least one support member 31 is connected to the middle of the connecting plate 10, and other support members 31 can be connected to the periphery of the connecting plate 10 between the support legs 20.

[0041] In this embodiment, the support member 31 in the middle of the connecting plate 10 has a cross-shaped transverse cross section, and the other support members 31 are not limited in shape and are located in the extension direction of the cross-shaped support member 31 to form a larger discontinuous cross-shaped structure therewith.

[0042] like Figure 6 As shown, the support structure 30 of the lower tube base of the fuel assembly according to the fourth embodiment of the present invention is a discontinuous cross-shaped structure.

[0043] The support structure 30 includes a plurality of support members 31, which are dispersedly arranged along a cross below the connecting plate 10. At least one support member 31 is connected to the middle of the connecting plate 10, and other support members 31 can be connected to the periphery of the connecting plate 10 between the support legs 20.

[0044] The difference from the third embodiment is that the support member 31 in the middle of the connecting plate 10 has a circular cross section, and the other support members 31 have any shape and are located in four extending directions of the circular support member 31 to form a larger discontinuous cross structure.

[0045] Furthermore, if Figure 1 , 3 As shown in FIG. 4 , the lower tube seat of the present invention further includes a skirt 40 . The skirt 40 is connected below the connecting plate 10 and between the adjacent supporting legs 20 .

[0046] The lower end of the skirt 40 facing away from the support structure 30 and the lower end of the support leg 20 facing away from the support structure 30 are respectively provided with chamfers.

[0047] In addition, in the lower tube seat of the present invention, the support structure 30 and the support legs 20 can be formed integrally on the connecting plate 10, or can be provided separately and then connected as one.

[0048] The fuel assembly of the present invention comprises any one of the lower tube seats in the first to fourth embodiments, and also comprises a plurality of fuel rods, a spacer grid, a guide tube, an upper tube seat, etc., which can all be realized by using existing technologies.

[0049] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A lower tube base of a fuel assembly, characterized in that: It comprises a connecting plate (10), a plurality of supporting legs (20) and a supporting structure (30); the plurality of supporting legs (20) are connected at intervals below the connecting plate (10), and the supporting structure (30) is connected between the plurality of supporting legs (20) below the connecting plate (10); The support structure (30) is a continuous cross-shaped structure, and the support structure (30) divides the space below the connecting plate (10) into four spaced chambers, wherein the four chambers respectively correspond to four inlets of the lower core plate for spraying coolant; The bottom surface of the support structure (30) is flush with the bottom surface of the support leg (20).

2. The lower tube socket of the fuel assembly according to claim 1, characterized in that: The support structure (30) comprises one or more support members (31).

3. The lower tube socket of the fuel assembly according to claim 2, characterized in that: A plurality of the support members (31) are connected.

4. The lower tube socket of the fuel assembly according to claim 2, characterized in that: The longitudinal cross-sectional shape of the support member (31) is at least one of a rectangular shape, a trapezoidal shape, a conical shape, a streamline shape and a special shape; The cross-sectional shape of the support member (31) is at least one of a rectangular shape, a cross shape, a circular shape and a special shape.

5. The lower tube socket of the fuel assembly according to claim 1, characterized in that: The connection plate (10) is provided with a plurality of through holes (11) penetrating the upper and lower surfaces of the connection plate (10); the support structure (30) is located below the connection plate (10) and avoids the through holes (11).

6. The lower tube socket of the fuel assembly according to claim 1, characterized in that: The supporting structure (30) is located in the middle of the connecting plate (10) and extends towards the periphery of the connecting plate (10).

7. The lower tube socket of the fuel assembly according to any one of claims 1 to 6, characterized in that: The lower tube seat further comprises a skirt (40); the skirt (40) is connected below the connecting plate (10) and between the adjacent supporting legs (20).

8. A fuel assembly, characterized in that: It comprises the lower tube seat as described in any one of claims 1 to 7.

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