Support grid for nuclear fuel assembly chf and method of adjusting fuel rod bend size

Abstract

This invention discloses a support grid for a nuclear fuel assembly (CHF) and a method for adjusting the bending dimensions of fuel rods. The method includes a support grid body, a support structure providing support for the fuel rods, and a support member that contacts the fuel rods and provides a bending fulcrum. The support grid body has an mounting structure; a portion of the mounting structure extends beyond the end face of the support grid body; the support structure is connected to the mounting structure, and a portion of the support structure also extends beyond the end face of the support grid body; the support member is located at one end of the support structure and beyond the end face of the support grid body. This invention's support grid for the CHF nuclear fuel assembly ensures that the bending point of the fuel rods is outside the end face of the support grid body, avoiding the influence of the support grid on the flow channel area and fluid velocity, thus making the experimental results of the nuclear fuel assembly critical heat flux density test more reliable.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor technology, and in particular to a support grid for a nuclear fuel assembly (CHF) and a method for adjusting the bending dimensions of fuel rods. Background Technology

[0002] In the rod bending critical heat flux density (CHF) test simulating the thermal hydraulic conditions of a pressurized water reactor, a 5×5 rod bundle is generally used, and in some conditions, the fuel rods need to be bent.

[0003] Currently, bending of fuel rods can be achieved using a rod bending support grid. Existing rod bending support grids are based on a 5×5 support grid, adding a support structure at the bending point to provide lateral force to the fuel rod, thus causing it to bend. This support structure is located inside the support grid and has rigid protrusions punched into it. Therefore, this support structure places the maximum bending point of the fuel rod inside the support grid, causing the support grid to affect the fluid state. Furthermore, this support structure is a planar support structure with low stiffness. Additionally, there is no specific connection point between the support structure and the support grid, making accurate positioning difficult to guarantee. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address at least one defect of the related technologies mentioned in the background art: the support structure causes the maximum bending position of the fuel rod to be located inside the support grid, so that the support grid will affect the fluid state, and to provide a support grid for nuclear fuel assembly CHF.

[0005] Another technical problem to be solved by the present invention is to provide a method for adjusting the bending size of fuel rods.

[0006] The technical solution adopted by the present invention to solve its technical problem is: to construct a support grid for a nuclear fuel assembly (CHF), including a support grid body, a support structure that provides support for the fuel rods, and a support member that contacts the fuel rods and provides a bending fulcrum;

[0007] The supporting grid body is provided with an installation structure; a portion of the installation structure extends beyond the end face of the supporting grid body.

[0008] The supporting structure is connected to the mounting structure, and a portion of the supporting structure extends beyond the end face of the supporting grid body;

[0009] The support member is located at one end of the support structure and outside the end face of the support grid body.

[0010] Preferably, in the support grid of the nuclear fuel assembly CHF according to the present invention, the support grid further includes a support plate, one end of which is connected to the mounting structure, and the other end of which is connected to the support structure and provides support for the support structure.

[0011] Preferably, in the support grid of the nuclear fuel assembly CHF according to the present invention, the mounting structure is provided with two first mortises; the two ends of the support structure are respectively provided with first tenons; the first tenons are inserted into and connected to the first mortises.

[0012] Preferably, in the support grid of the nuclear fuel assembly CHF according to the present invention, the mounting structure is further provided with a second tenon; the end of the support piece away from the support structure is provided with a second tenon; the second tenon is inserted into and connected to the second tenon.

[0013] Preferably, in the support grid of the nuclear fuel assembly CHF of the present invention, the support structure is further provided with a third tenon in the middle; the support piece is further provided with a third tenon at one end near the support structure; the third tenon is inserted into and connected to the third tenon.

[0014] Preferably, in the support grid of the nuclear fuel assembly CHF according to the present invention, the third tenon is provided above the support member, and the third tenon is correspondingly provided at the position of the support piece relative to the third tenon.

[0015] Preferably, in the support grid of the nuclear fuel assembly CHF according to the present invention, the support piece is further provided with a connecting part; the connecting part is located below the third tenon and protrudes from the third tenon; the connecting part is connected to the inner side of the support member.

[0016] Preferably, in the support grid of the nuclear fuel assembly CHF according to the present invention, the support structure is an arched structure; the support member is a bridge-shaped rigid protrusion punched in the middle of the lower part of the support structure.

[0017] Preferably, in the support grid of the nuclear fuel assembly CHF according to the present invention, the support structure has an end of the support member that is flush with the end of the mounting structure.

[0018] The present invention also provides a method for adjusting the bending dimensions of fuel rods, using the support grid of the nuclear fuel assembly (CHF) as described in any of the preceding claims; adjusting the relative position and relative angle between the support structure and the mounting structure.

[0019] By implementing this invention, the following beneficial effects are achieved:

[0020] The support grid of the nuclear fuel assembly CHF of the present invention enables the maximum bending position of the fuel rods to be achieved outside the grid, reducing the influence of the support grid on the flow channel area and fluid velocity, so that CHF occurs at the maximum bending position as much as possible, and thus obtaining more accurate experimental results. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0022] Figure 1 This is a top view of the support grid of the nuclear fuel assembly CHF of the present invention;

[0023] Figure 2 This is a front view of the support grid of the nuclear fuel assembly CHF of the present invention;

[0024] Figure 3 This is a partial structural schematic diagram of the support grid of the nuclear fuel assembly CHF of the present invention;

[0025] Figure 4 This is the present invention. Figure 3 An explosion diagram;

[0026] Figure 5 This is the present invention. Figure 3 A schematic diagram of the supporting structure;

[0027] Figure 6 This is the present invention. Figure 3 A schematic diagram of the support sheet structure;

[0028] Figure 7 This is a schematic diagram of the method for adjusting the bending size of fuel rod 4 according to the present invention. Detailed Implementation

[0029] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0031] In the description of the invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of the invention, unless otherwise stated, "a plurality of" means two or more.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or a chemical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] See Figures 1 to 6 An embodiment of the present invention discloses a support grid for a nuclear fuel assembly (CHF), including a support grid body 1, a support structure 2 that provides support for fuel rods 4, and a support member 5 that contacts the fuel rods 4 and provides a bending fulcrum.

[0034] The supporting grid body 1 is provided with an installation structure 11; a portion of the installation structure 11 extends beyond the end face of the supporting grid body 1; a supporting structure 2 is connected to the installation structure 11, and a portion of the supporting structure 2 extends beyond the end face of the supporting grid body 1; a supporting member 5 is provided at one end of the supporting structure 2 and is located beyond the end face of the supporting grid body 1. The supporting member 5 can be an independent structure connected and fixed to the supporting structure 2. The connection and fixing methods can be welding, tenon and mortise connection, fastener fixing, etc.; the supporting member 5 can also be directly stamped on the supporting structure 2. Preferably, the end of the supporting structure 2 where the supporting member 5 is located is flush with the end of the installation structure 11.

[0035] The support member 5 on the support structure 2 is located outside the end face of the support grid body 1, which can make the maximum bending position of the fuel rod 4 located outside the support grid of the nuclear fuel assembly CHF, reducing the impact of the support grid body on the flow channel area and fluid flow velocity.

[0036] Specifically:

[0037] To enhance the strength of the support structure 2, a support plate 3 is also included. One end of the support plate 3 is connected to the mounting structure 11, and the other end of the support plate 3 is connected to the support structure 2 and provides support for the support structure 2.

[0038] To accurately locate the connection position of support structure 2 on the support grid of the nuclear fuel assembly CHF, such as Figure 4 and Figure 5 As shown, the mounting structure 11 has two first mortises 111; the support structure 2 has first tenons 22 at both ends; the first tenons 22 are inserted into the first mortises 111, and the first mortises 111 and the first tenons 22 are welded together for fixation. The support structure 2 and the mounting structure 11 are positioned and connected by mortises and tenons, which can ensure the installation position accuracy of the support structure 2, and thus ensure the accuracy of the closure dimension between the bent fuel rod 4 and the adjacent fuel rod 4.

[0039] To accurately locate the connection position of support piece 3 on the support grid of the nuclear fuel assembly CHF, such as Figure 4 and Figure 6 As shown, the mounting structure 11 is also provided with a second mortise 112; the support piece 3 is provided with a second tenon 31 at one end away from the support structure 2; the second tenon 31 is inserted into and connected to the second mortise 112, and the second mortise 112 and the second tenon 31 are welded and fixed.

[0040] In order to connect the support plate 3 to the support structure 2 and provide effective support to the support structure 2, such as Figures 4 to 6 As shown, the support structure 2 is also provided with a third mortise 23 in the middle; the support piece 3 is also provided with a third tenon 32 at one end near the support structure 2; the third tenon 32 is inserted into and connected to the third mortise 23.

[0041] Furthermore, such as Figures 4 to 6 As shown, the third mortise 23 is located above the support member 5, and the third tenon 32 is correspondingly located on the support piece 3 opposite to the third mortise 23. Preferably, the support piece 3 also has a connecting portion 33; the connecting portion 33 is located below the third tenon 32 and protrudes from the third tenon 32; the connecting portion 33 connects to the inner side of the support member 5. The connecting portion 33 protrudes from the third tenon 32, can contact and abut against the inner side of the support member 5, and enhance the strength of the support member 5.

[0042] To enhance the rigidity of the support structure 2, the support structure 2 is an arched structure; the support member 5 is a bridge-shaped rigid protrusion punched in the middle of the lower part of the support structure 2.

[0043] See Figure 7One embodiment of the present invention discloses a method for adjusting the bending dimension of fuel rod 4, using the support grid of the nuclear fuel assembly CHF described in any of the above embodiments; adjusting the relative position and relative angle between the support structure 2 and the mounting structure 11. By adjusting the relative position and relative angle A between the support structure 2 and the mounting structure 11, various degrees of closure between the bent rods in the fuel rod 4 and adjacent fuel rods can be achieved as needed.

[0044] By implementing this invention, the following beneficial effects are achieved:

[0045] The support grid of the nuclear fuel assembly CHF of the present invention enables the maximum bending point of the fuel rod to occur outside the grid, reducing the influence of the support grid on the flow channel area and fluid velocity, so that CHF occurs as close as possible to the maximum bending point, thereby obtaining more accurate experimental results.

[0046] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that for those skilled in the art, the above embodiments or technical features can be freely combined, and several modifications and improvements can be made without departing from the concept of the present invention. These all fall within the protection scope of the present invention. That is, the embodiments described "in some embodiments" can be freely combined with any of the embodiments above and below. Therefore, all equivalent transformations and modifications made within the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A support grid for a nuclear fuel assembly (CHF), characterized in that, It includes a support grid body (1), a support structure (2) that provides support for the fuel rods (4), and a support member (5) that contacts the fuel rods (4) and provides a bending fulcrum. The supporting grid body (1) is provided with an installation structure (11); a portion of the installation structure (11) extends beyond the end face of the supporting grid body (1); The support structure (2) is connected to the mounting structure (11), and a portion of the support structure (2) extends beyond the end face of the support grid body (1); The support member (5) is located at one end of the support structure (2) and outside the end face of the support grid body (1).

2. The support grid for the nuclear fuel assembly (CHF) according to claim 1, characterized in that, The support grid also includes a support plate (3), one end of which is connected to the mounting structure (11), and the other end of which is connected to the support structure (2) and provides support for the support structure (2).

3. The support grid for the nuclear fuel assembly (CHF) according to claim 1, characterized in that, The mounting structure (11) is provided with two first mortises (111); the two ends of the support structure (2) are respectively provided with first tenons (22); the first tenons (22) are inserted into and connected to the first mortises (111).

4. The support grid for the nuclear fuel assembly (CHF) according to claim 2, characterized in that, The mounting structure (11) is also provided with a second mortise (112); the support piece (3) is provided with a second tenon (31) at one end away from the support structure (2); the second tenon (31) is inserted into and connected to the second mortise (112).

5. The support grid for the nuclear fuel assembly (CHF) according to claim 2, characterized in that, The support structure (2) is also provided with a third mortise (23) in the middle; the support piece (3) is also provided with a third tenon (32) at one end near the support structure (2); the third tenon (32) is inserted into and connected to the third mortise (23).

6. The support grid for the nuclear fuel assembly (CHF) according to claim 5, characterized in that, The third mortise (23) is located above the support member (5), and the third tenon (32) is located on the support piece (3) relative to the third mortise (23).

7. The support grid for the nuclear fuel assembly CHF according to claim 5, characterized in that, The support piece (3) is also provided with a connecting part (33); the connecting part (33) is located below the third tenon (32) and protrudes from the third tenon (32); the connecting part (33) is connected to the inner side of the support member (5).

8. The support grid for the nuclear fuel assembly (CHF) according to claim 1, characterized in that, The support structure (2) is an arched structure; the support member (5) is a bridge-shaped rigid protrusion punched in the middle of the lower part of the support structure (2).

9. The support grid for the nuclear fuel assembly CHF according to any one of claims 1-8, characterized in that, The support structure (2) has an end of the support member (5) flush with the end of the mounting structure (11).

10. A method for adjusting the bending dimensions of a fuel rod (4), characterized in that, Use the support grid of the nuclear fuel assembly CHF according to any one of claims 1-9; adjust the relative position and relative angle of the support structure (2) and the mounting structure (11).

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