Positioning grid for fuel rods and fuel assembly

Abstract

This application relates to the field of nuclear fuel technology, specifically to a positioning grid and fuel assembly suitable for fuel rods, comprising: a frame assembly configured to form multiple receiving spaces; each of multiple clamping assemblies configured to have both ends connected to the frame assembly, configured to be elastically deformable, and configured to have an adjustable distance between its ends. When the fuel rod is inserted into the receiving space, the clamping assemblies exert no force on the fuel rod; after the fuel rod is inserted, by adjusting the distance, the clamping assemblies exert a force on the fuel rod. This application embodiment, by adjusting the distance between the two ends of the clamping assemblies, avoids surface scratches on the fuel rod when it is inserted into the receiving space, reduces the probability of wear on the fuel rod, thereby preventing surface debris from affecting the abrasion of the fuel rod, ensuring the safety of the fuel assembly operation, and achieving relatively stable positioning of the fuel rod after it is inserted into the receiving space.

Description

Technical Field

[0001] The embodiments of this application relate to the field of nuclear fuel technology, specifically to a positioning grid and fuel assembly suitable for fuel rods. Background Technology

[0002] The statements herein are provided merely as background information in connection with this application and do not necessarily constitute prior art.

[0003] Reactor fuel assemblies are crucial components of nuclear reactors, primarily consisting of fuel rods, positioning grids, and other structures. Inside a nuclear power plant reactor, fuel assemblies are loaded into the reactor core, where nuclear fission generates heat energy, which is then converted into electrical energy.

[0004] Positioning grids are structural components used to secure fuel rods. As reactor fuel assembly designs continue to evolve, the requirements for positioning grids also change. Positioning grids include support frames, which are in direct contact with the fuel rods and are key components for determining their position. However, current positioning grids have many shortcomings in positioning the fuel rods. Summary of the Invention

[0005] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0006] In a first aspect, embodiments of this application provide a positioning grid suitable for fuel rods, comprising: a frame assembly configured to form a plurality of receiving spaces and configured for inserting fuel rods; and a plurality of clamping assemblies, each of the plurality of clamping assemblies configured to be movably and fixedly connected to the frame assembly at both ends, configured to be elastically deformable, and configured to be adjustable in distance between its ends. When the fuel rod is inserted into the receiving space, the clamping assemblies exert no force on the fuel rod; after the fuel rod is inserted into the receiving space, by adjusting the distance, the clamping assemblies exert force on the fuel rod to position it.

[0007] The embodiments of this application, by configuring the clamping component to be elastically deformable and the distance between its two ends adjustable, facilitate the adjustment of the degree of elastic deformation of the clamping component by adjusting the distance between its two ends. This allows for the adjustment of the force applied by the clamping component to the fuel rod, ensuring that the clamping component exerts no force on the fuel rod when it is inserted into the receiving space. This avoids scratches on the surface of the fuel rod, reduces the probability of wear, and prevents the impact of fuel rod surface shedding on the abrasion of the fuel rod by debris, thus ensuring the safe operation of the fuel assembly. Furthermore, after the fuel rod is inserted into the receiving space, the clamping component can exert a force on the fuel rod, achieving a relatively stable and effective positioning of the fuel rod.

[0008] Secondly, embodiments of this application also provide a fuel assembly, which includes: a plurality of fuel rods and a positioning grid according to embodiments of this application, wherein the fuel rods are disposed within the positioning grid.

[0009] These and other advantages of this application will become more apparent from the following detailed description of preferred embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0010] To further illustrate the above and other advantages and features of this application, the specific embodiments of this application will be described in more detail below with reference to the accompanying drawings. The drawings, together with the following detailed description, are included in and form a part of this specification. Elements having the same function and structure are indicated by the same reference numerals. It should be understood that these drawings only depict typical examples of this application and should not be considered as limiting the scope of this application.

[0011] Figure 1 This is a schematic diagram of the structure of a positioning grid applicable to fuel rods according to an embodiment of this application;

[0012] Figure 2 yes Figure 1 The top view of the positioning grid shown;

[0013] Figure 3 This is a schematic diagram of the clamping component in the first state according to an embodiment of this application;

[0014] Figure 4 yes Figure 3 A cross-sectional view of the clamping assembly shown;

[0015] Figure 5 This is a schematic diagram of the clamping component in the second state according to an embodiment of this application;

[0016] Figure 6 This is a schematic diagram of the clamping component in the third state according to an embodiment of this application.

[0017] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding.

[0018] Explanation of reference numerals in the attached figures:

[0019] 10. Positioning grid;

[0020] 11. Frame assembly; 111. Accommodating space; 112. First frame component; 1121. Mating part; 113. Second frame component;

[0021] 12. Clamping assembly; 121. Elastic element; 122. Mating part; 1221. Fixing part; 1222. Connecting part. Detailed Implementation

[0022] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.

[0023] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0024] It should be noted that, unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning as understood by a person with ordinary skills in the field to which this application pertains.

[0025] In the description of the embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In related technologies, commonly used positioning grids include strip-type positioning grids, cell-type positioning grids, and wire-wound positioning structures. These positioning grids have many shortcomings. For example, cell-type positioning grids consist of a surrounding plate and multiple cell tubes. When clamping fuel rods, they mainly rely on the frictional force limited by the elastic interference fit between the cells and the fuel rods and the guide tubes to maintain the position of the fuel rods. This method of clamping fuel rods cannot adjust the clamping force. When inserting fuel rods into the cells, the high frictional force easily leads to severe scratches on the surface of the fuel rods. As a result, during the operation of the fuel assembly, the detached debris has an adverse effect on the erosion of the fuel rods.

[0027] To address the aforementioned technical problems, embodiments of this application provide a positioning grid suitable for fuel rods. Figure 1 This is a schematic diagram of the structure of a positioning grid applicable to fuel rods according to an embodiment of this application. Figure 2 yes Figure 1 The top view of the positioning grid shown is as follows: Figure 1 and Figure 2 As shown, the positioning grid 10 includes a frame assembly 11 and a plurality of clamping assemblies 12.

[0028] The frame assembly 11 is configured to form a plurality of receiving spaces 111 and is configured to be inserted by fuel rods.

[0029] Multiple clamping assemblies 12 are provided, each of which is movably and fixedly connected to the frame assembly 11 at both ends, is elastically deformable, and the distance between its two ends is adjustable. When the fuel rod is inserted into the receiving space 111, the clamping assembly 12 exerts no force on the fuel rod. After the fuel rod is inserted into the receiving space 111, by adjusting the distance, the clamping assembly 12 can exert a force on the fuel rod so that the fuel rod can be positioned.

[0030] The embodiments of this application, by configuring the clamping component 12 to be elastically deformable and the distance between its two ends to be adjustable, facilitate the adjustment of the degree of elastic deformation of the clamping component 12 by adjusting the distance between its two ends. This achieves the purpose of adjusting the force applied by the clamping component 12 to the fuel rod, so that when the fuel rod is inserted into the receiving space 111, the clamping component 12 exerts no force on the fuel rod, avoiding scratches on the surface of the fuel rod, reducing the probability of wear on the fuel rod, and thus preventing the impact of fuel rod surface shedding on the abrasion of the fuel rod by residue, ensuring the safety of the fuel assembly operation. Furthermore, after the fuel rod is inserted into the receiving space 111, the clamping component 12 can exert a force on the fuel rod, achieving a relatively stable and effective positioning of the fuel rod.

[0031] In some embodiments, the fact that each clamping component 12 is movably and fixedly connected to the frame component 11 at both ends can be understood as: either end is detachable from the frame component 11, and when connected to the frame component 11, its final connection state is a fixed connection.

[0032] In some embodiments, the clamping component 12 is configured such that one end is fixed to the frame component 11, and the other end is adjustable on the frame component 11 to adjust the distance between the two ends of the clamping component 12, thereby adjusting the degree of its elastic deformation, which is relatively simple to operate.

[0033] In some embodiments, one end of the clamping component 12 is welded to the frame component 11 to fix it in place.

[0034] In some embodiments, the clamping component 12 is configured such that both ends of it can be adjusted on the frame component 11 to adjust the distance between the two ends of the clamping component 12, thereby adjusting the degree of its elastic deformation, which is relatively simple to operate.

[0035] In some embodiments, Figure 3 This is a schematic diagram of the clamping component in the first state according to an embodiment of this application. Figure 4 yes Figure 3 The cross-sectional view of the clamping assembly shown is as follows: Figure 3 and Figure 4 As shown, the clamping assembly 12 includes an elastic element 121 and a mating element 122. Both ends of the elastic element 121 are fixedly connected to the mating element 122. Multiple mating portions 1121 are formed in the frame assembly 11. A mating member 122 is configured to mate with the mating portions 1121 and is configured to move from one mating portion 1121 to another under the action of an external force. When the mating member 122 is within the mating portion 1121, the mating portion 1121 and the mating member 122 are fixedly connected, so that the mating member 122 is fixedly connected to the frame assembly 11. When the mating member 122 moves from one mating portion 1121 to another mating portion 1121, the distance between the two mating members 122 changes, so that the elastic member 121 changes from an extended state to a bent state, so that the elastic member 121 has no force on the fuel rod when the fuel rod is inserted into the receiving space 111. After the fuel rod is inserted into the receiving space 111, by adjusting the distance, the elastic member 121 can exert a force on the fuel rod so that the fuel rod can be positioned.

[0036] The embodiments of this application provide multiple mating parts 1121 on the frame assembly 11, and configure the mating parts 122 to move from one mating part 1121 to another mating part 1121 under the action of external force, so as to change the distance between the two mating parts 122, thereby changing the degree of elastic deformation of the elastic member 121, so as to change it from a stretched state to a bent state. The operation is relatively simple, and the force applied to the fuel rod by the elastic member 121 in the bent state ensures that the fuel rod is stably positioned.

[0037] Figure 5 This is a schematic diagram of the clamping component in the second state according to an embodiment of this application. Figure 6 This is a structural diagram of the clamping component in the third state according to an embodiment of this application, as shown below. Figure 3 , Figure 5 as well as Figure 6 As shown, when the clamping assembly 12 is in the first state, the two mating parts 122 engage with the two mating portions 1121 that are far apart. At this time, the elastic member 121 is in an extended state, and the mating parts 122 and the mating portions 1121 are fixedly connected. During the process of inserting the fuel rod into the receiving space 111, the elastic member 121 exerts no force on the fuel rod, that is, the elastic member 121 will not scratch the surface of the fuel rod. When the clamping assembly 12 is in the second state, the two mating parts 122 are separated from the mating portions 1121. At this time, the clamping assembly 12 and the frame assembly 11 are in a disassembled state. When the clamping assembly 12 is in the third state, the two mating parts 122 engage with the two mating portions 1121 that are close together. At this time, the fuel rod has been inserted into the receiving space 111, the elastic member 121 is in a bent state, and the mating parts 122 and the mating portions 1121 are fixedly connected. The elastic member 121 can apply a supporting force to the fuel rod, so that the fuel rod can be positioned.

[0038] In such an embodiment, such as Figure 3 As shown, the two mating parts 1121 that are closer together are the two mating parts 1121 that are other than the two mating parts 1121 that are furthest apart among the multiple mating parts 1121.

[0039] In such an embodiment, the first state is an extended state and the third state is a bent state.

[0040] In some embodiments, after the elastic member 121 changes from a stretched state to a bent state, the elastic member 121 protrudes toward the center of the receiving space 111.

[0041] In some embodiments, the elastic element 121 is a spring structure, and the material of the elastic element 121 is a deformable shape memory alloy.

[0042] In such an embodiment, the elastic element 121 is a double-sided triple-bend spring structure.

[0043] In some embodiments, after the fuel rod is inserted into the receiving space 111 and the mating member 122 is moved from one mating part 1121 to another mating part 1121, that is, after the elastic member 121 changes from a stretched state to a bent state, the entire location of the positioning grid 10 is heat-treated in a heating furnace to solidify the shape of the elastic member 121 and eliminate the stress generated during assembly.

[0044] In some embodiments, the clamping assembly 12 includes an elastic element 121 and a mating element 122. One end of the elastic member 121 is fixedly connected to the mating member 122, and the other end of the elastic member 121 is fixedly connected to the frame assembly 11. Multiple mating portions 1121 are formed in the frame assembly 11. The mating member 122 is configured to mate with the mating portions 1121 and is configured to move from one mating portion 1121 to another under the action of an external force. When the mating member 122 is within a mating portion 1121, the mating portion 1121 and the mating member 122 are fixedly connected, so that the mating member 122 is fixedly connected to the frame assembly 11. When the mating member 122 moves from one mating portion 1121 to another, the distance between the two ends of the elastic member 121 changes, causing the elastic member 121 to change from an extended state to a bent state. This ensures that when the fuel rod is inserted into the receiving space 111, the elastic member 121 exerts no force on the fuel rod. After the fuel rod is inserted into the receiving space 111, by adjusting the distance, the elastic member 121 can exert a force on the fuel rod, so that the fuel rod can be positioned.

[0045] The embodiments of this application provide multiple mating parts 1121 on the frame assembly 11, and configure the mating parts 122 in the clamping assembly 12 to move from one mating part 1121 to another mating part 1121 under the action of external force, so as to change the distance between the two mating parts 122, thereby changing the degree of elastic deformation of the elastic member 121, so that it changes from a stretched state to a bent state. The operation is relatively simple, and the force applied to the fuel rod by the elastic member 121 in the bent state ensures that the fuel rod is stably positioned.

[0046] In some embodiments, the mating member 122 forms a fixing portion 1221 and a connecting portion 1222. The fixing portion 1221 is formed at both ends of the connecting portion 1222, and the mating portion 1121 is formed in a shape that mates with the fixing portion 1221 so that the fixing portion 1221 can be fixed to the mating portion 1121; wherein, one end of the elastic member 121 is fixedly connected to the connecting portion 1222.

[0047] The embodiments of this application utilize the cooperation between the fixing part 1221 and the cooperating part 1121 of the cooperating part 122 to fix the elastic member 121 connected to the connecting part 1222 onto the frame assembly 11, thereby ensuring the stability of the connection between the elastic member 121 and the frame assembly 11.

[0048] In some embodiments, the mating member 122 is configured as an "I" shape, the mating part 1121 is configured as an "I" shaped hole, and the fixing part 1221 engages with the mating part 1121 to prevent the fixing part 1221 from shaking, thereby further improving the stability of the connection between the elastic member 121 and the frame assembly 11.

[0049] In some embodiments, the fixing part 1221 is the "-" part in the "I" structure, and the connecting part 1222 is the "|" part in the "I" type structure.

[0050] In some embodiments, a plurality of I-shaped holes are arranged adjacent to each other that mate with the same fixing part 1221, so as to improve the convenience of moving the mating part 122 from one mating part 1121 to another mating part 1121.

[0051] In some embodiments, if one end of the elastic member 121 is fixedly connected to the mating member 122 and the other end is fixedly connected to the frame assembly 11, then the I-shaped holes of the plurality of I-shaped holes that respectively mate with the same fixing part 1221 are configured to have a predetermined spacing.

[0052] In some embodiments, the frame assembly 11 includes a first frame member 112 and a second frame member 113. A plurality of first frame members 112 are configured to cooperate with each other to form a plurality of receiving spaces 111. The first frame members 112 are fixedly connected to the second frame members 113. The second frame members 113 are disposed outside the first frame members 112. A plurality of clamping assemblies 12 are fixedly connected to the plurality of first frame members 112.

[0053] The embodiments of this application form multiple accommodating spaces 111 through the cooperation between the first frame member 112 and the second frame member 113, so as to accommodate multiple fuel rods respectively using the multiple accommodating spaces 111, which facilitates flexible adjustment of the number of fuel rods accommodated and has a wide range of applications.

[0054] In some embodiments, the second frame member 113 is a polygonal strip structure, such as a quadrilateral strip structure or a hexagonal strip structure. The first frame member 112 is a combination structure composed of strips that cooperate with each other.

[0055] In such an embodiment, each strip in the first frame member 112 and the second frame member 113 is provided with a slot, through which multiple strips can be connected and welded together to form a frame assembly 11.

[0056] exist Figure 1 and Figure 2 In the embodiment shown, the first frame member 112 and the second frame member 113 together form a square grid space (accommodation space 111).

[0057] In some embodiments, the frame assembly 11 includes a first frame member 112 and a second frame member 113. A plurality of first frame members 112 are configured to cooperate with each other to form a plurality of receiving spaces 111. The first frame members 112 are fixedly connected to the second frame members 113. The second frame members 113 are disposed outside the first frame members 112. A plurality of clamping assemblies 12 are fixedly connected to the plurality of first frame members 112.

[0058] The embodiments of this application form multiple accommodating spaces 111 through the cooperation between the first frame member 112 and the second frame member 113, so as to accommodate multiple fuel rods respectively using the multiple accommodating spaces 111, which facilitates flexible adjustment of the number of fuel rods accommodated and has a wide range of applications.

[0059] In some embodiments, the mating portion 1121 is formed in the first frame member 112 to securely position the fuel rod located within the receiving space 111.

[0060] In some embodiments, for any accommodating space 111, a plurality of clamping components 12 are fixedly connected to the corresponding portion of the first frame member 112, and the inner walls of the accommodating space 111 where the plurality of clamping components 12 are located are not the same.

[0061] Embodiments of this application also provide a method for assembling fuel rods and positioning grid 10, the assembly method including steps S1 to S4.

[0062] S1. Fix the two mating parts 122 in the clamping assembly 12 to the two mating parts 1121 on the first frame part 112 that are far apart, so that the elastic member 121 is in the first state.

[0063] S2. Insert the fuel rod into the receiving space 111 of the frame assembly 11.

[0064] S3. Apply a first external force to the clamping assembly 12 to separate the two mating parts 122 of the clamping assembly 12 from the two mating parts 1121 on the first frame member 112 that are far apart, thereby putting the elastic member 121 in the second state.

[0065] S4. Continue to apply a second external force to the clamping assembly 12, so that the two mating parts 122 of the clamping assembly 12 are fixedly connected to the two mating parts 1121 that are close to each other on the first frame member 112, thereby putting the elastic member 121 in the third state, so as to use the elastic member 121 to clamp the fuel rod.

[0066] The method provided in the embodiments of this application adjusts the connection state between the mating part 122 in the clamping assembly 12 and the different mating parts 1121 in the frame assembly 11 to adjust the force applied by the clamping assembly 12 to the fuel rod. This ensures that the clamping assembly 12 exerts no force on the fuel rod when it is inserted into the receiving space 111, thus avoiding scratches on the surface of the fuel rod, reducing the probability of wear, and preventing the impact of fuel rod surface shedding on the abrasion of the fuel rod by debris. This ensures the safety of the fuel assembly operation. Furthermore, after the fuel rod is inserted into the receiving space 111, the clamping assembly 12 can exert a strong force on the fuel rod, achieving a relatively stable and effective positioning of the fuel rod.

[0067] An embodiment of this application also provides a fuel assembly, which includes: a plurality of fuel rods and a positioning grid 10 according to an embodiment of this application, wherein the fuel rods are disposed within the positioning grid 10.

[0068] The embodiments of this application, by placing the fuel rods within the positioning grid 10, can prevent surface scratches on the fuel rods, reduce the probability of wear on the fuel rods, thereby preventing the impact of fuel rod surface shedding on the abrasion of the fuel rods by debris, ensuring the safety of the fuel assembly operation, and ensuring the stability of the fuel rod positioning.

[0069] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0070] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A positioning grid suitable for fuel rods, characterized in that, It includes: A frame assembly configured to form a plurality of receiving spaces and configured to be into which fuel rods are inserted; A plurality of clamping assemblies, each of the plurality of clamping assemblies being configured such that both ends of the clamping assembly are movably and fixedly connected to the frame assembly, configured to be elastically deformable, and configured such that the distance between the ends of the clamping assembly is adjustable, wherein the clamping assembly exerts no force on the fuel rod when the fuel rod is inserted into the receiving space, and after the fuel rod is inserted into the receiving space, the clamping assembly exerts a force on the fuel rod by adjusting the distance to position the fuel rod.

2. The positioning grid according to claim 1, characterized in that, The clamping component is configured such that one end is fixed to the frame component, and the other end is adjustable in position on the frame component.

3. The positioning grid according to claim 1, characterized in that, The clamping assembly is configured such that both ends of it can be adjusted in position on the frame assembly.

4. The positioning grid according to claim 3, characterized in that, The clamping assembly includes an elastic element and a mating element, with both ends of the elastic element fixedly connected to the mating element. The frame assembly forms multiple mating parts, and the mating member is configured to mate with the mating parts and to be able to move from one mating part to another under the action of an external force. When the mating member is in the mating part, the mating part is fixedly connected to the mating member so that the mating member is fixedly connected to the frame assembly. When the mating member moves from one mating part to another, the distance between the two mating members changes, causing the elastic member to change from a stretched state to a bent state. This results in the elastic member exerting no force on the fuel rod when it is inserted into the receiving space. After the fuel rod is inserted into the receiving space, by adjusting the distance, the elastic member can exert a force on the fuel rod to position it.

5. The positioning grid according to claim 2, characterized in that, The clamping assembly includes an elastic element and a mating element. One end of the elastic element is fixedly connected to the mating element, and the other end of the elastic element is fixedly connected to the frame assembly. The frame assembly forms multiple mating parts, and the mating member is configured to mate with the mating parts and to be able to move from one mating part to another under the action of an external force. When the mating member is in the mating part, the mating part is fixedly connected to the mating member so that the mating member is fixedly connected to the frame assembly. When the mating member moves from one mating part to another, the distance between the two ends of the elastic member changes, causing the elastic member to change from a stretched state to a bent state. This prevents the elastic member from exerting any force on the fuel rod when it is inserted into the receiving space. After the fuel rod is inserted into the receiving space, by adjusting the distance, the elastic member can exert a force on the fuel rod to position it.

6. The positioning grid according to claim 4 or 5, characterized in that, The mating part forms a fixing part and a connecting part. The fixing part is formed at both ends of the connecting part, and the mating part is formed in a shape that mates with the fixing part so that the fixing part can be fixed to the mating part. One end of the elastic element is fixedly connected to the connecting part.

7. The positioning grid according to claim 6, characterized in that, The mating part is configured to be "I" shaped, the mating portion is configured to be "I" shaped hole, and the fixing portion mates with the mating portion.

8. The positioning grid according to claim 7, characterized in that, The plurality of "I"-shaped holes are arranged adjacent to each other, each of which mates with the same fixing part.

9. The positioning grid according to claim 1, characterized in that, The frame assembly includes a first frame member and a second frame member, wherein multiple first frame members are configured to cooperate with each other to form multiple accommodating spaces. The first frame member is configured to be fixedly connected to the second frame member, and the second frame member is located on the outside of the first frame member. The plurality of clamping components are configured to be fixedly connected to the plurality of the first frame members.

10. The positioning grid according to any one of claims 5, 7 and 8, characterized in that, The frame assembly includes a first frame member and a second frame member, wherein multiple first frame members are configured to cooperate with each other to form multiple accommodating spaces. The first frame member is configured to be fixedly connected to the second frame member, and the second frame member is located on the outside of the first frame member. The plurality of clamping components are configured to be fixedly connected to the plurality of the first frame members.

11. The positioning grid according to claim 10, characterized in that, The mating part is configured to be formed on the first frame member.

12. A fuel assembly, characterized in that, It includes: Multiple fuel rods and the positioning grid as described in any one of claims 1-11, The fuel rods are disposed within the positioning grid.

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