Nuclear fuel assembly CHF test supporting grillwork and fuel rod closing degree adjusting method

Abstract

The invention provides a nuclear fuel assembly CHF test supporting grillwork and a fuel rod closure degree adjusting method, the supporting grillwork comprises a body, the body comprises a first lattice cell, a second lattice cell and a third lattice cell which are adjacent to one another, and the second lattice cell is located in the middle of the body; each first lattice cell comprises two inclined supports which are connected with each other and are arranged at an included angle, so that the fuel rods penetrating through the first lattice cells are eccentrically bent; one ends of the fuel rods in the first lattice cells abut against the inclined supports, and the other ends of the fuel rods in the first lattice cells abut against the guide pipes in the second lattice cells; or the other ends of the fuel rods in the first lattice cells abut against the side walls, deviating from the inclined supporting sides, of the first lattice cells. According to the CHF test supporting grillwork for the nuclear fuel assembly, the two inclined supports with the included angle are arranged in the first lattice cell, the inclined supports are matched with the guide pipe or the side wall, so that a larger contact area can be formed between the inclined supports and the fuel rod, enough rigidity is achieved, the bending position of the fuel rod can be kept unchanged, and the accuracy of test data is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear reactors, and in particular to a nuclear fuel assembly CHF test support grid and a fuel rod closure adjustment method. Background Art

[0002] In the critical heat flux (CHF) test of pressurized water reactor fuel assembly rod bending, in order to maintain the rod bending closure, it is necessary to design and process a special rod bending support grid to support and position the bent rods and maintain the closure of the test piece rod bundle during the test.

[0003] At present, the rod bending and fixing method mostly adopts the grid form. The existing technology mostly adopts the traditional strip form to manufacture the rod bending grid, and ensures the clamping support of the bent rod by punching or welding special support features on the strip. The fuel rod support features (rigid convex or spring) of this support grid are arranged horizontally, which is easy to scratch the fuel rod.

[0004] Moreover, this type of support grid needs to be punched and formed using a mold and assembled and welded. For the punching of special-shaped strips, a new mold needs to be developed, which is expensive and has a long R&D cycle. For example, referring to the prior art, the patent application number: 202211336723.X, named Support Grid for Nuclear Fuel Assembly CHF and Method for Adjusting the Bending Size of Fuel Rods, the support grid is composed of multiple parts. During the test, under the hydraulic action of the fluid, there is a risk of loosening of the connection parts, resulting in the inability to maintain the closure of the rod bundle.

[0005] Based on this, the inventor of the present application proposes a nuclear fuel assembly CHF test support grid and a fuel rod closure adjustment method in order to solve the above technical problems. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of the prior art that the support grid is high in cost and has poor stability in maintaining the closure of the rod bundle, and to provide a nuclear fuel assembly CHF test support grid and a method for adjusting the closure of the fuel rods.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] The present invention provides a nuclear fuel assembly CHF test support grid, which is characterized in that it includes:

[0009] A body, comprising a first grid cell, a second grid cell and a third grid cell adjacent to each other, wherein the second grid cell is located in the middle of the body;

[0010] The first grid cell includes two oblique supports connected to each other and arranged at an angle, so that the fuel rod passing through the first grid cell is eccentrically bent;

[0011] One end of the fuel rod in the first cell abuts against the oblique support, and the other end abuts against the guide tube in the second cell; or the other end of the fuel rod in the first cell abuts against the side wall of the first cell away from the oblique support.

[0012] According to one embodiment of the present invention, a plurality of fourth gate cells are further arranged around the outer periphery of the first gate cell, the second gate cell and the third gate cell;

[0013] The first gate cell, the second gate cell, the third gate cell and the fourth gate cell are arranged in a matrix.

[0014] According to one embodiment of the present invention, the body is designed to be integrated, and the design method is any one of 3D printing, casting and machining.

[0015] According to one embodiment of the present invention, the first gate cell and the second gate cell are arranged diagonally, two third gate cells are arranged on adjacent sides of the first gate cell and the second gate cell, and the two third gate cells are arranged diagonally;

[0016] One end of the two oblique supports facing the second grid element is provided with a support protrusion, and the fuel rod abuts against the support protrusion.

[0017] According to an embodiment of the present invention, the connection angle between the first gate element and the second gate element is chamfered, so that the connection angles of the two third gate elements are inwardly contracted to form a first supporting surface and a second supporting surface;

[0018] The fuel rod located in the first grid cell abuts against the first supporting surface and the second supporting surface.

[0019] According to one embodiment of the present invention, the first supporting surface and the second supporting surface are symmetrically arranged with the connecting line from the first gate element to the second gate element as an axis;

[0020] The two oblique supports are also symmetrically arranged with the connecting line from the first grid element to the second grid element as an axis.

[0021] According to one embodiment of the present invention, the first gate cell, the second gate cell and the third gate cell are arranged adjacent to each other, and the first gate cell is located between the second gate cell and the third gate cell, and the first gate cell, the second gate cell and the third gate cell are arranged at right angles;

[0022] The first grid cell is opened toward one side of the second grid cell. One end of the fuel rod in the first grid cell abuts against the inclined support, and the other end abuts against the guide tube in the second grid cell.

[0023] According to one embodiment of the present invention, both of the two oblique supports are provided with support protrusions, one end of the fuel rod in the first grid cell abuts against the support protrusion, and the other end abuts against the guide tube in the second grid cell; or,

[0024] The other end is in contact with the side wall of the first gate element away from the inclined support, and a supporting protrusion is also provided on the side wall of the first gate element away from the inclined support.

[0025] According to an embodiment of the present invention, the side plate connecting the first grid cell and the third grid cell is retracted toward the third grid cell.

[0026] The present invention also provides a method for adjusting the closure of a fuel rod, using the nuclear fuel assembly CHF test support grid as described above, the method comprising:

[0027] By adjusting the position of the oblique support and the height of the support protrusion, the closing degree of the fuel rod in the first grid element can meet the requirements.

[0028] The positive and progressive effects of the present invention are:

[0029] The nuclear fuel assembly CHF test support grid of the present invention has two inclined supports with an included angle arranged in the first grid element. The inclined supports cooperate with the guide tube or the side wall to have a larger contact area with the fuel rod and have sufficient rigidity to keep the bending position of the fuel rod unchanged, thereby ensuring the accuracy of the test data. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which:

[0031] Figure 1 It is a structural schematic diagram of an embodiment of a nuclear fuel assembly CHF test support grid of the present invention;

[0032] Figure 2 for Figure 1 axonometric drawing;

[0033] Figure 3 It is a structural schematic diagram of another embodiment of a nuclear fuel assembly CHF test support grid of the present invention;

[0034] Figure 4 It is a structural schematic diagram of another embodiment of a nuclear fuel assembly CHF test support grid of the present invention;

[0035] Figure 5 It is a structural schematic diagram of another embodiment of the nuclear fuel assembly CHF test support grid of the present invention.

[0036] 1. Ontology;

[0037] 2. first gate element; 21. oblique support; 22. support protrusion;

[0038] 3. The second gate element;

[0039] 4. third gate element; 41. first supporting surface; 42. second supporting surface;

[0040] 5. The fourth gate element. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0043] Please refer to Figures 1 to 5 The present invention proposes a nuclear fuel assembly CHF test support grid, including a main body 1, the main body 1 includes a first grid cell 2, a second grid cell 3 and a third grid cell 4 adjacent to each other, the second grid cell 3 is located in the middle of the main body 1; the first grid cell 2 includes two oblique supports 21 connected and set at an angle, so that the fuel rods passing through the first grid cell 2 are eccentrically bent; one end of the fuel rod in the first grid cell 2 abuts against the oblique support 21, and the other end abuts against the guide tube in the second grid cell 3; or, the other end of the fuel rod in the first grid cell 2 abuts against the side wall of the first grid cell 2 away from the oblique support 21.

[0044] The closure is the distance between the fuel rods. When the two fuel rods are in contact, the closure is zero, i.e. 100% closure. If the theoretical gap between the fuel rods is a, when the fuel rods are bent to a gap of 0.2a, the closure is 80%.

[0045] When the fuel rods in the first cell 2 are bent toward the first cell 2 or the third cell 4 under the action of the oblique support 21 , the closing degree between the fuel rods in the first cell 2 and the fuel rods in the third cell 4 is adjusted.

[0046] Two oblique supports 21 set at an angle are arranged in the first grid cell 2, so that the fuel rod passing through the first grid cell 2 is eccentrically bent, one end of the fuel rod forms an effective abutment with the two oblique supports 21 respectively, and the other end of the fuel rod forms an abutment with the guide tube in the second grid cell 3 or the side wall of the first grid cell 2.

[0047] Therefore, under the effective contact between the oblique support 21 and the side wall, the fuel rod can maintain its complete position unchanged, thereby ensuring the accuracy of the test data.

[0048] It can be seen that the two inclined supports 21 and the side walls of the first grid element 2 are both part of the structure of the first grid element 2 itself. On the one hand, the contact area between the inclined supports 21 and the side walls and the fuel rods is larger; on the other hand, the first grid element 2 has sufficient rigidity in supporting the fuel rods. The stronger the support stability, the more accurate the test data can be ensured.

[0049] A plurality of fourth gate cells 5 are disposed around the outer periphery of the first gate cell 2 , the second gate cell 3 and the third gate cell 4 ; the first gate cell 2 , the second gate cell 3 , the third gate cell 4 and the fourth gate cell 5 are arranged in a matrix.

[0050] It can be seen that the first grid cell 2, the second grid cell 3, the third grid cell 4 and the fourth grid cell 5 are all connected adjacently and share a side plate. For example, the adjacent first grid cell 2 and the adjacent second grid cell 3 share a side plate.

[0051] With such arrangement, the supporting grid is easier to process and the overall structural strength is higher.

[0052] In one embodiment, the body 1 is designed as an integrated molding, and the design method is any one of 3D printing, casting and machining.

[0053] In this way, the support grid proposed by the present invention does not have parts and connection structures, the overall structure has higher reliability, and can maintain the geometric structure under the hydraulic action of high-speed fluid.

[0054] Please refer to Figure 1 , Figure 2 , Figure 3 and Figure 5 The first grid cell 2 and the second grid cell 3 are arranged diagonally, and two third grid cells 4 are arranged on adjacent sides of the first grid cell 2 and the second grid cell 3, and the two third grid cells 4 are arranged diagonally; two inclined supports 21 are provided with support protrusions 22 at one end facing the second grid cell 3, and the fuel rods are in contact with the support protrusions 22.

[0055] A support protrusion 22 is provided on the oblique support 21 , so that the fuel rod abuts against the support protrusion 22 instead of the support grid.

[0056] The support protrusions 22 can provide a more stable support for the fuel rods and can simulate the radial positioning of the fuel rods to keep the fuel rods straight.

[0057] The closing degree of the fuel rod can be adjusted by adjusting the height of the support protrusions 22; and by adjusting different numbers of support protrusions 22, it can be ensured that the support protrusions 22 cooperate with the guide tube or the side wall to form an effective abutment against the fuel rod.

[0058] Optionally, the connecting corners of the first grid cell 2 and the second grid cell 3 are chamfered, and the connecting corners of the two third grid cells 4 are retracted to form a first supporting surface 41 and a second supporting surface 42; the fuel rod located in the first grid cell 2 is in contact with the first supporting surface 41 and the second supporting surface 42.

[0059] That is, one end of the fuel rod in the first grid cell 2 abuts against the two inclined supports 21, and the other end abuts against the fuel rod through two inclined surfaces, thereby improving the positioning effect of the fuel rod.

[0060] The two inclined surfaces correspond to the first supporting surface 41 and the second supporting surface 42 mentioned above.

[0061] In order to avoid setting up additional supporting parts in the first grid cell 2 and the second grid cell 3, the connecting angle position of the first grid cell 2 and the second grid cell 3 is opened, and at the same time, the two side plates of the first grid cell 2 are retracted toward the third grid cell 4. On the one hand, the accommodating space of the first grid cell 2 is expanded to accommodate the fuel rods; on the other hand, the first supporting surface 41 and the second supporting surface 42 formed after the retraction can form an effective abutment against the fuel rods.

[0062] That is, the two opposite ends of the fuel rod in the first cell 2 are respectively clamped by the two supporting protrusions 22 and the two supporting surfaces, so as to ensure that the bending position of the fuel rod will not change and ensure the accuracy of the test data.

[0063] Furthermore, the first support surface 41 and the second support surface 42 are symmetrically arranged with the connecting line from the first grid cell 2 to the second grid cell 3 as the axis; the two oblique supports 21 are also symmetrically arranged with the connecting line from the first grid cell 2 to the second grid cell 3 as the axis.

[0064] It can be seen that, with the diagonal line connecting the first gate element 2 and the second gate element 3 as a reference, the support protrusions 22 on the two oblique supports 21 are symmetrically arranged with the first support surface 41 and the second support surface 42 .

[0065] In this way, the fuel card can be set at the corner of the first grid cell 2 close to the second grid cell 3, and the distance from the two third grid cells 4 is consistent, so that the closure test can be carried out with the fuel rods of the two third grid cells 4 at the same time, improving the test efficiency.

[0066] Please refer to Figure 4The first grid cell 2, the second grid cell 3 and the third grid cell 4 are arranged adjacent to each other, and the first grid cell 2 is located between the second grid cell 3 and the third grid cell 4, and the first grid cell 2, the second grid cell 3 and the third grid cell 4 are arranged at right angles; the first grid cell 2 is opened toward one side of the second grid cell 3, and one end of the fuel rod in the first grid cell 2 abuts against the inclined support 21, and the other end abuts against the guide tube in the second grid cell 3.

[0067] In some other embodiments, the other end of the fuel rod in the first cell 2 may also abut against the inner wall of the first cell 2 . Specifically, different schemes may be selected according to the inclination angle of the inclined support 21 and the space occupied by the fuel rod in the first cell 2 .

[0068] Specifically, an opening may be provided between the first cell 2 and the third cell 4 to support the fuel rod in the first cell 2 with a guide tube, or a non-opening may be provided between the first cell 2 and the third cell 4 so that the inner wall of the first cell 2 abuts against the fuel rod in the first cell 2.

[0069] That is, the fuel rods in the first cell 2 are positioned by the inclined supports 21 and the guide tubes in the second cell 3 .

[0070] In order to improve the limiting effect of the fuel rod, a supporting protrusion 22 is also provided on the inclined support 21 .

[0071] Furthermore, the side plate connecting the first grid cell 2 and the third grid cell 4 is retracted toward the third grid cell 4 .

[0072] With such arrangement, the center position of the fuel rod in the first cell 2 can be adjusted so that the fuel rod bends toward the third cell 4 to adjust the degree of closure between the fuel rod in the first cell 2 and the fuel rod in the third cell 4 .

[0073] It should be noted that the second grid cell 3, the third grid cell 4 and the fourth grid cell 5 can be provided with a support protrusion 22, and the support protrusion 22 is a semicircular or chamfered arc structure, thereby preventing the fuel rod from being scratched during the fuel rod threading process.

[0074] By optimizing the structure of the supporting grid, sharp and fine features in the grid can be avoided, and the discharge effect between the grid and the fuel rods in the live test can be effectively reduced.

[0075] In summary, in the CHF test support grid of the nuclear fuel assembly of the present invention, two inclined supports 21 with an angle are arranged in the first grid element 2. The inclined supports 21 cooperate with the guide tube or the side wall to have a larger contact area with the fuel rod and have sufficient rigidity to keep the bending position of the fuel rod unchanged, thereby ensuring the accuracy of the test data.

[0076] The present invention provides a method for adjusting the closure of a fuel rod, using the above nuclear fuel assembly CHF test support grid, the method for adjusting the closure of the fuel rod comprises:

[0077] By adjusting the position of the oblique support 21 and the height of the support protrusion 22, the closing degree of the fuel rods in the first grid cell 2 can meet the requirements.

[0078] That is, by adjusting the position of the oblique support 21 and the height of the support protrusion 22 , the bending of various closing sizes between the fuel rod in the first cell 2 and the adjacent fuel rods can be achieved.

[0079] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "install", "connect", "connect", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can also be a mechanical connection. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0080] The present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or multiple times in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0081] Although the present invention is disclosed as above with reference to the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention.

[0082] Therefore, any modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A nuclear fuel assembly CHF test support grid, characterized in that: include: A body, comprising a first grid cell, a second grid cell and a third grid cell adjacent to each other, wherein the second grid cell is located in the middle of the body; The first grid cell includes two oblique supports connected to each other and arranged at an angle, so that the fuel rod passing through the first grid cell is eccentrically bent; One end of the fuel rod in the first cell abuts against the oblique support, and the other end abuts against the guide tube in the second cell; or the other end of the fuel rod in the first cell abuts against the side wall of the first cell away from the oblique support.

2. The nuclear fuel assembly CHF test support grid according to claim 1, characterized in that: A plurality of fourth gate cells are disposed around the outer periphery of the first gate cell, the second gate cell and the third gate cell; The first gate cell, the second gate cell, the third gate cell and the fourth gate cell are arranged in a matrix.

3. The nuclear fuel assembly CHF test support grid according to claim 1, characterized in that: The body is designed to be integrated, and the design method is any one of 3D printing, casting and machining.

4. The nuclear fuel assembly CHF test support grid according to claim 1, characterized in that: The first gate element and the second gate element are arranged diagonally, two third gate elements are arranged on adjacent sides of the first gate element and the second gate element, and the two third gate elements are arranged diagonally; One end of the two oblique supports facing the second grid element is provided with a support protrusion, and the fuel rod abuts against the support protrusion.

5. The nuclear fuel assembly CHF test support grid according to claim 4, characterized in that: The connecting angle between the first grid element and the second grid element is chamfered, so that the connecting angles of the two third grid elements are inwardly contracted to form a first supporting surface and a second supporting surface; The fuel rod located in the first grid cell abuts against the first supporting surface and the second supporting surface.

6. The nuclear fuel assembly CHF test support grid according to claim 5, characterized in that: The first supporting surface and the second supporting surface are symmetrically arranged with the connecting line from the first gate element to the second gate element as an axis; The two oblique supports are also symmetrically arranged with the connecting line from the first grid element to the second grid element as an axis.

7. The nuclear fuel assembly CHF test support grid according to claim 1, characterized in that: The first gate cell, the second gate cell and the third gate cell are arranged adjacent to each other, and the first gate cell is located between the second gate cell and the third gate cell, and the first gate cell, the second gate cell and the third gate cell are arranged at right angles; The first grid cell is opened toward one side of the second grid cell, one end of the fuel rod in the first grid cell abuts against the inclined support, and the other end abuts against the guide tube in the second grid cell; Alternatively, the other end abuts against a side wall of the first gate element facing away from the oblique support.

8. The nuclear fuel assembly CHF test support grid according to claim 7, characterized in that: The two inclined supports are each provided with a supporting protrusion, one end of the fuel rod in the first grid element abuts against the supporting protrusion, and the other end abuts against the guide tube in the second grid element; or, The other end is in contact with the side wall of the first gate element away from the inclined support, and a supporting protrusion is also provided on the side wall of the first gate element away from the inclined support.

9. The nuclear fuel assembly CHF test support grid according to claim 8, characterized in that: The side plate connecting the first grid cell and the third grid cell is retracted toward the third grid cell.

10. A method for adjusting the closure of a fuel rod, characterized in that: Using the nuclear fuel assembly CHF test support grid as described in any one of claims 1 to 9, the method comprises: By adjusting the position of the oblique support and the height of the support protrusion, the closing degree of the fuel rod in the first grid element can meet the requirements.

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