CN117809864A - Annular fuel assembly and method of manufacture - Google Patents

Abstract

Embodiments of the present application provide an annular fuel assembly comprising: a plurality of annular fuel elements, the inside of which contains fuel pellets, the plurality of annular fuel elements are arranged in an array manner to form a fuel rod bundle in regular polygon arrangement; a plurality of positioning portions, each positioning portion including a support member and a wire wound spirally around the support member; the box body is coated outside the fuel rod bundle; the plurality of positioning parts are respectively arranged in a first space surrounded by the adjacent annular fuel elements, and under the action of the plurality of positioning parts, gaps are formed between the adjacent two annular fuel elements so as to allow the coolant entering between the annular fuel elements from the bottom of the annular fuel assembly to flow along the axial direction of the annular fuel elements through the gaps, and the radial direction mixing can be generated so as to further ensure that the annular fuel elements are sufficiently cooled. Embodiments of the present application also provide a method of manufacturing an annular fuel assembly.

Description

Annular fuel assembly and method of manufacture

Technical Field

At least one embodiment of the present application relates to a fuel assembly, and more particularly to an annular fuel assembly and method of manufacture.

Background

The fuel assembly is a core component of the reactor, the annular fuel is used as a novel fuel, and the annular fuel is provided with an inner coolant channel and an outer coolant channel, so that the temperature of the fuel center can be greatly reduced, and the safety of the reactor can be greatly improved. The annular fuel element has an increased outer diameter compared to existing solid fuel rods, resulting in a fuel assembly with a high water-to-uranium ratio.

To achieve better economy, the arrangement between annular fuel elements is more compact, minimizing the gap between adjacent annular fuel elements. Thus, prior art annular fuel assemblies typically employ spacer grids to position the annular fuel elements. However, the limit value of the gap of the annular fuel rod of the existing annular fuel assembly cannot arrange a mixing wing structure on the spacer grid, so that most of the coolant flowing between the annular fuel elements from the bottom of the annular fuel assembly flows along the axial direction of the annular fuel elements, and the coolant cannot effectively flow along the radial direction of the annular fuel elements, thereby adversely affecting the thermal hydraulic performance under the annular fuel accident condition, and being unfavorable for fully playing the advantages of the annular fuel in terms of safety and economy.

Disclosure of Invention

In view of the above, the present application provides an annular fuel assembly and method of manufacture that overcomes or at least partially addresses the above.

According to a first aspect of embodiments of the present application, there is provided an annular fuel assembly comprising: a plurality of annular fuel elements, wherein the inside of the annular fuel elements contains fuel pellets, and the annular fuel elements are arranged in an array manner to form a fuel rod bundle in regular polygon arrangement; a plurality of positioning parts, each of which comprises a support member and a wire winding spirally wound outside the support member; the box body is coated outside the fuel rod bundle; the positioning parts are respectively arranged in a first space surrounded by the adjacent annular fuel elements, and under the action of the positioning parts, gaps are formed between the adjacent two annular fuel elements so as to allow coolant entering between the annular fuel elements from the bottom of the annular fuel assembly to flow along the axial direction of the annular fuel elements through the gaps and generate mixing along the radial direction of the annular fuel elements.

According to a second aspect of embodiments of the present application, there is provided a method of manufacturing an annular fuel assembly, the method of manufacturing being applied to an annular fuel assembly according to the first aspect of embodiments of the present application, the method of manufacturing comprising: spirally winding a wire around the outside of a support, both ends of the wire being welded to the support to form a positioning portion; the positioning parts are respectively combined with the annular fuel elements, and the annular fuel elements combined with the positioning parts are arranged in an array to form a fuel rod bundle in regular polygon arrangement; and sleeving a box body outside the fuel rod bundle so as to position the edge of the fuel rod bundle.

According to the annular fuel assembly provided by the embodiment of the application, the plurality of positioning parts are respectively arranged in the first space surrounded by the adjacent plurality of annular fuel elements, so that a gap is formed between the adjacent two annular fuel elements, and the coolant entering between the annular fuel elements from the bottom of the annular fuel assembly is allowed to flow along the radial direction of the annular fuel elements through the gap. Therefore, the heat exchange capacity of the annular fuel element can be enhanced, the central temperature of the annular fuel element is further reduced, and the safety of the annular fuel assembly is improved. According to the manufacturing method of the annular fuel assembly, the positioning parts are formed by spirally winding wires on the outer side of the supporting piece, the positioning parts are respectively combined with the annular fuel elements, the annular fuel elements combined with the positioning parts are arranged in an array mode, the annular fuel assembly capable of forming gaps between two adjacent annular fuel elements is manufactured, and the heat exchange capacity of the annular fuel elements is improved.

Drawings

FIG. 1 is a top view of an annular fuel assembly made up of square-arrayed fuel bundles according to an exemplary embodiment of the present application;

FIG. 2 is a top view of an annular fuel assembly made up of fuel bundles in a regular hexagonal arrangement according to another exemplary embodiment of the present application;

FIG. 3 is a schematic illustration of an assembly between four adjacent annular fuel elements in two adjacent rows and two adjacent columns and a first locating portion of the annular fuel assembly shown in FIG. 1;

FIG. 4 is a schematic illustration of an assembly of three adjacent annular fuel elements with a second locating portion of the annular fuel assembly of FIG. 2;

FIG. 5 is a top view of a first positioning portion of the annular fuel assembly of the present application;

FIG. 6 is a cross-sectional view of a thin-walled circular tube of a first positioning portion of an annular fuel assembly of the present application;

FIG. 7 is a top view of a second detent of the annular fuel assembly of the present application; and

fig. 8 is a schematic perspective view of a second positioning portion of the annular fuel assembly of the present application.

In the figure:

1. an annular fuel element; 11. a fuel bundle;

2. a positioning part;

21. a support; 211. a thin-walled circular tube; 212. opening holes; 213. a solid round bar;

22. winding wires;

23. a first positioning portion;

24. a second positioning portion;

3. a case body;

4. a first space;

5. a second space;

6. a guide tube;

7. and a third space.

Detailed Description

For the purposes, technical solutions and advantages of the present application, the technical solutions of the present application will be clearly and completely described below with reference to the drawings of the embodiments of the present application. It will be apparent that the described embodiments are one embodiment of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without the benefit of the present disclosure, are intended to be within the scope of the present application based on the described embodiments.

It is to be noted that unless otherwise defined, technical or scientific terms used herein should be taken in a general sense as understood by one of ordinary skill in the art to which this application belongs. If, throughout, reference is made to "first," "second," etc., the description of "first," "second," etc., is used merely for distinguishing between similar objects and not for understanding as indicating or implying a relative importance, order, or implicitly indicating the number of technical features indicated, it being understood that the data of "first," "second," etc., may be interchanged where appropriate. If "and/or" is present throughout, it is meant to include three side-by-side schemes, for example, "A and/or B" including the A scheme, or the B scheme, or the scheme where A and B are satisfied simultaneously.

According to an inventive concept of one aspect of the present application, there is provided an annular fuel assembly comprising: a plurality of annular fuel elements, the inside of which contains fuel pellets, the plurality of annular fuel elements are arranged in an array manner to form a fuel rod bundle in regular polygon arrangement; a plurality of positioning portions, each positioning portion including a support member and a wire wound spirally around the support member; the box body is coated outside the fuel rod bundle; the positioning parts are respectively arranged in a first space surrounded by the adjacent annular fuel elements, and under the action of the positioning parts, gaps are formed between the adjacent two annular fuel elements so as to allow the coolant entering between the annular fuel elements from the bottom of the annular fuel assembly to flow along the axial direction of the annular fuel elements through the gaps and generate stirring along the radial direction of the annular fuel elements.

FIG. 1 is a top view of an annular fuel assembly made up of square-arrayed fuel bundles according to an exemplary embodiment of the present application; FIG. 2 is a top view of an annular fuel assembly made up of fuel bundles in a regular hexagonal arrangement according to another exemplary embodiment of the present application; FIG. 3 is a schematic illustration of an assembly between four adjacent annular fuel elements in two adjacent rows and two adjacent columns and a first locating portion of the annular fuel assembly shown in FIG. 1; FIG. 4 is a schematic illustration of an assembly of three adjacent annular fuel elements with a second locating portion of the annular fuel assembly of FIG. 2.

Referring to fig. 1-4, an annular fuel assembly is provided according to an exemplary embodiment of the present application, including a plurality of annular fuel elements 1, a plurality of positioning portions 2, and a cartridge 3. The plurality of annular fuel elements 1 internally contain fuel pellets, and the plurality of annular fuel elements 1 are arranged in an array to form a fuel bundle 11 in a regular polygon arrangement. Each positioning portion 2 comprises a support 21 and a wire 22 helically wound around the outside of the support 21. The cartridge 3 is wrapped around the outside of the fuel bundle 11. Wherein the plurality of positioning portions 2 are respectively provided inside the first space 4 surrounded by the adjacent plurality of annular fuel elements 1, and a gap is formed between the adjacent two annular fuel elements 1 by the plurality of positioning portions 2 to allow the coolant entering between the annular fuel elements 1 from the bottom of the annular fuel assembly to flow in the axial direction of the annular fuel elements 1 through the gap and to generate a stirring in the radial direction of the annular fuel elements 1.

In the present embodiment, by disposing the plurality of positioning portions 2 inside the first space 4 surrounded by the adjacent plurality of annular fuel elements 1, respectively, a gap is formed between the adjacent two annular fuel elements 1 by the action of the plurality of positioning portions 2. At the same time, by providing the positioning portion 2 comprising the support 21 and the wires 22 spirally wound on the outside of the support 21, the coolant entering between the annular fuel elements 1 from the bottom of the annular fuel assembly can flow along the wires 22 spirally to allow the coolant entering between the annular fuel elements 1 from the bottom of the annular fuel assembly to flow in the axial direction of the annular fuel elements 1 through the gap and to generate a mixing in the radial direction of the annular fuel elements 1. In this way, the heat exchange capacity of the annular fuel element 1 can be enhanced, the central temperature of the annular fuel element 1 can be further reduced, and the safety of the annular fuel assembly can be improved.

Further, the above arrangement improves the ability of the annular fuel assembly to mix the coolant therein. The existing annular fuel assembly adopts a positioning grid to position the annular fuel elements, the strips in the positioning grid and the supporting frame structure are in a sheet shape, and the radial mixing of the coolant between the annular fuel elements cannot be enhanced in a mixing wing mode due to the small space. Compared with the existing annular fuel assembly, the annular fuel assembly of this embodiment can continuously generate the coolant flow direction along the same direction as the winding direction of the wires 22 in the axial direction of the annular fuel element 1 by arranging the positioning part 2 comprising the supporting member 21 and the wires 22 spirally wound outside the supporting member 21, and the coolant can generate different axial and radial flow ratios according to different winding angles of the wires 22, so that the heat exchange capacity of the annular fuel element 1 is enhanced, the central temperature of the annular fuel element 1 is further reduced, and the safety of the annular fuel element 1 is improved.

In addition, the existing annular fuel assembly adopts a positioning grid to position the annular fuel element, the positioning grid consists of a lamellar strip and a supporting frame, the annular fuel element is radially limited by utilizing a rigid protrusion of the supporting frame, and the rigid protrusion structure is in a vibration condition for a long time and is easy to generate fatigue failure. And the strip and the support frame are mutually connected and fixed by spot welding, so that the number of the welding spots is large, and the failure probability is high. When the rigid convex structure and the welding spot fail, tiny foreign matters are easy to generate in a reactor coolant loop, so that the safety of the reactor is influenced. Compared with the existing annular fuel assembly, the annular fuel assembly is simple in structure, low in probability of mixing fine foreign matters in the coolant, few in welding spots and greatly reduced in welding seam failure probability.

In some exemplary embodiments, referring to fig. 1-2, a second space 5 is formed between two adjacent annular fuel elements 1 and the cartridge body 3, the second space 5 being provided with a positioning portion 2 inside.

By the arrangement, the annular fuel assembly of the present embodiment can improve the physical and thermal properties of the annular fuel element 1. In the existing annular fuel assembly, the structural cavities of the annular fuel elements are large, the water-uranium ratio is high, and the advantages of the safety performance and the economic performance of the annular fuel elements cannot be fully exerted. Compared with the existing annular fuel assembly, the positioning portion 2 disposed in the first space 4 and the second space 5 of the present embodiment structurally occupies a part of the cavity volume inside the annular fuel assembly, so as to indirectly increase the flow velocity of the coolant between the annular fuel elements 1, reduce the water-to-uranium ratio of the annular fuel assembly, and improve the physical performance and thermal performance of the annular fuel assembly.

In some exemplary embodiments, referring to fig. 1-2, the annular fuel assembly further includes a plurality of pilot tubes 6. Each guide tube 6 replaces one annular fuel element 1, and a plurality of guide tubes 6 are arranged in an array with a plurality of annular fuel elements 1 to form a fuel bundle 11 in a regular polygonal arrangement to allow control rod assemblies or other stationary related components to be inserted into the guide tubes 6 for easy connection of the control rod assemblies or other stationary related components to the annular fuel assemblies.

In this embodiment, the safety of the annular fuel assembly is enhanced by providing a plurality of guide tubes 6 in the annular fuel assembly that allow for the insertion of control rod assemblies or other stationary related assemblies to facilitate the integration of the control rod assemblies or other stationary related assemblies with the annular fuel assembly, thereby facilitating the control of the reactivity or bypass fraction of the annular fuel in the core.

In this embodiment, the stationary related components include a choke plug assembly, a burnable poison assembly, and a neutron source assembly.

In the present embodiment, 8 guide tubes 6 are provided. The plurality of annular fuel elements 1 are arranged in line to form a square arrangement of fuel bundles 11, and 4 adjacent annular fuel elements 1 in adjacent two rows and adjacent two columns are arranged in a square, each guide tube 6 replacing one of the 4 adjacent annular fuel elements 1. Alternatively, a plurality of annular fuel elements 1 are arranged in a staggered manner to form a fuel bundle 11 in a regular hexagonal arrangement, and every two adjacent 3 annular fuel elements 1 are arranged in a regular triangle, and each guide tube 6 replaces one of every two adjacent 3 annular fuel elements 1.

Fig. 5 is a top view of a first positioning portion of the annular fuel assembly of the present application.

In some exemplary embodiments, referring to fig. 1, 3 and 5, a plurality of annular fuel elements 1 are arranged in line to form a square arrangement of fuel bundles 11, and the positioning portions 2 disposed inside the first space 4 and inside the second space 5 are each a first positioning portion 23 using a thin-walled circular tube 211 as a support 21. The diameter of the thin-walled circular tube 211 of the first positioning portion 23 arranged in the first space 4 is larger than the diameter of the thin-walled circular tube 211 of the first positioning portion 23 arranged in the second space 5.

In this embodiment, an example is shown in which a plurality of annular fuel elements 1 are formed into a fuel bundle 11 in a square arrangement of 13 rows and 13 columns.

FIG. 6 is a cross-sectional view of a thin walled circular tube of a first positioning portion of an annular fuel assembly of the present application.

In some exemplary embodiments, referring to fig. 6, at least one opening 212 is provided in the sidewall of the thin-walled circular tube 211, which may be distributed at different locations on the sidewall of the thin-walled circular tube 211 as desired. The top of the thin-walled circular tube 211 is closed or provided with micro holes, and the size of the micro holes is far smaller than that of the openings 212 on the side wall of the thin-walled circular tube 211, so that the coolant flowing into the thin-walled circular tube 211 from the bottom of the thin-walled circular tube 211 flows out through the openings 212, and the radial flow of the coolant in the fuel assembly is further promoted, so that the heat exchange effect of the annular fuel element 1 is enhanced.

Fig. 7 is a top view of a second detent of the annular fuel assembly of the present application.

In some exemplary embodiments, referring to fig. 1 and 7, a second positioning portion 24 having a solid round bar 213 as a support 21 is provided inside the third space 7 formed between the corner of the cartridge body 3 and the annular fuel element 1.

In this embodiment, the second positioning portion 24 disposed in the third space 7 structurally occupies a part of the cavity volume inside the annular fuel assembly, so as to indirectly increase the flow velocity of the coolant between the annular fuel elements 1, reduce the water-uranium ratio of the annular fuel assembly, and improve the physical performance and thermal performance of the annular fuel assembly.

In the present embodiment, the sizes and forms of the positioning portions 2 provided in the first space 4, the second space 5, and the third space 7 are different based on the difference in the sizes of the first space 4, the second space 5, and the third space 7 formed inside the annular fuel assembly. The positioning portion 2 is divided into a first positioning portion 23 and a second positioning portion 24 according to different structures.

In some exemplary embodiments, referring to fig. 1, 3 and 5, 4 adjacent annular fuel elements 1 in two adjacent rows and two adjacent columns are arranged in a square. Among the 4 adjacent annular fuel elements 1, the outer diameter D of the annular fuel element 1, the distance P between the centers of the adjacent two annular fuel elements 1, the outer diameter D2 of the thin-walled circular tube 211 of the first positioning portion 23 provided inside the first space 4, and the outer diameter dw of the wire winding 22 satisfy:

so that the first positioning portion 23 provided inside the first space 4 is in contact with or has a gap with the adjacent annular fuel element 1.

By the arrangement, the first positioning portion 23 arranged in the first space 4 is in contact with or has a gap with the adjacent annular fuel elements 1 to ensure that a gap is formed between the adjacent two annular fuel elements 1, and a certain interval is reserved for the assembly between the first positioning portion 23 and the adjacent 4 annular fuel elements 1 and the thermal expansion and irradiation swelling of the annular fuel elements 1 in the case that the first positioning portion 23 in the first space 4 has a gap with the adjacent annular fuel elements 1.

In the present embodiment, inIn this case, the first positioning portions 23 located inside the first space 4 are in contact with the adjacent 4 annular fuel elements 1, respectively, and a gap may still be formed between the adjacent two annular fuel elements 1.

In some exemplary embodiments, referring to fig. 2, 4 and 7, the plurality of annular fuel elements 1 are arranged in a staggered manner to form the fuel bundles 11 arranged in a regular hexagon, and the positioning portions 2 disposed inside the first space 4 and inside the second space 5 are the second positioning portions 24 using the solid round bars 213 as the supporting members 21.

In some exemplary embodiments, referring to fig. 2, 4 and 7, two adjacent 3 annular fuel elements 1 are arranged in a regular triangle. Among the adjacent 3 annular fuel elements 1, the outer diameter D of the annular fuel element 1, the distance P between the centers of the adjacent two annular fuel elements 1, the outer diameter D3 of the solid round bar 213 of the second positioning portion 24 provided in the first space 4, and the outer diameter dw of the wire winding 22 satisfy:

so that the second positioning portion 24 provided inside the first space 4 is in contact with or has a void with the adjacent annular fuel element 1.

By the above arrangement, the second positioning portion 24 provided inside the first space 4 is brought into contact with or has a clearance with the adjacent annular fuel elements 1 to ensure that a clearance is formed between the adjacent two annular fuel elements 1, and in the case where the second positioning portion 24 inside the first space 4 has a clearance with the adjacent annular fuel elements 1, a certain distance is left for the assembly between the second positioning portion 24 and the adjacent 3 annular fuel elements 1 and the thermal expansion and irradiation swelling of the annular fuel elements 1.

In the present embodiment, inThe second positioning portions 24 located inside the first space 4 are in contact with the adjacent 3 annular fuel elements 1, respectively, at which time a gap may still be formed between the adjacent two annular fuel elements 1.

In some exemplary embodiments, the wire 22 is a solid wire, and the wire 22 is helically wound on the support 21 at a constant pitch.

Fig. 8 is a schematic perspective view of a second positioning portion of the annular fuel assembly of the present application.

In some exemplary embodiments, referring to fig. 8, the wire 22 is a solid wire, and the wire 22 is helically wound on the support 21 at a pitch that decreases progressively in a direction from bottom to top of the support 21 to further enhance radial mixing of the coolant near the coolant outlet of the annular fuel assembly.

By the above arrangement, the pitch of the wire 22 near the top of the support 21 is made smaller than the pitch of the wire 22 near the bottom of the support 21, as shown in FIG. 8, H1> H2, to further enhance radial mixing of the coolant near the coolant outlet of the annular fuel assembly.

1-4, a method of manufacturing an annular fuel assembly is provided, the method being applied to an annular fuel assembly as described in any of the above embodiments, the method comprising: a wire 22 is spirally wound on the outside of the support 21, and both ends of the wire 22 are welded to the support 21 to form the positioning portion 2. The plurality of positioning portions 2 are respectively combined with the plurality of annular fuel elements 1, and the plurality of annular fuel elements 1 combined with the positioning portions 2 are arranged in an array to form a fuel rod bundle 11 in a regular polygon arrangement. The cartridge 3 is sleeved outside the fuel bundle 11 to locate the edges of the fuel bundle 11.

In the present embodiment, by spirally winding the wire 22 on the outer side of the support 21 to form the positioning portions 2, combining the plurality of positioning portions 2 with the plurality of annular fuel elements 1, respectively, and arranging the plurality of annular fuel elements 1 combined with the positioning portions 2 in an array, an annular fuel assembly capable of forming a gap between adjacent two annular fuel elements 1 is produced, enhancing the heat exchanging capability of the annular fuel elements 1.

Further, by manufacturing the annular fuel assembly by the above manufacturing method, the annular fuel assembly manufacturing economy can be improved. Existing annular fuel assembly manufacturing methods typically employ spacer grids to achieve radial positioning and axial displacement limiting of the fuel bundles. The positioning grid consists of very narrow strips, the strip structure is complex, corresponding punching grinding tools are required to be specially designed and manufactured, deformation is very easy to generate during assembly of the positioning grid, and scrapping is easy to generate. Compared with the manufacturing method of the annular fuel assembly in the prior art, the manufacturing method of the annular fuel assembly is convenient and quick to manufacture, and can greatly reduce the manufacturing cost of the annular fuel assembly, improve the manufacturing efficiency and shorten the development period.

In some exemplary embodiments, referring to fig. 1-2, a plurality of pilot tubes 6 are employed in place of a plurality of annular fuel elements 1. Wherein each guide tube 6 replaces one annular fuel element 1, so that a plurality of guide tubes 6 and a plurality of annular fuel elements 1 are arranged in an array to form a fuel rod bundle 11 in a regular polygon arrangement.

In some exemplary embodiments, referring to fig. 1, 3 and 5, the support 21 is made of a thin-walled circular tube 211, a wire 22 is spirally wound outside the thin-walled circular tube 211, both ends of the wire 22 are welded to both ends of the thin-walled circular tube 211, a first positioning portion 23 using the thin-walled circular tube 211 as the support 21 is formed, the plurality of first positioning portions 23 are respectively combined with the plurality of annular fuel elements 1, and the plurality of annular fuel elements 1 combined with the first positioning portions 23 are arranged in line to form the square-arrangement fuel bundle 11.

In some exemplary embodiments, referring to fig. 6, at least one opening is opened in the sidewall of the thin-walled tube 211 and the top is closed.

In addition, the top of the thin-walled tube 211 may also be perforated with micro-holes having a size that is substantially smaller than the size of the openings 212 in the side walls of the thin-walled tube 211.

In some exemplary embodiments, referring to fig. 1 and 7, the support 21 is made of a solid round bar 213, a wire 22 is spirally wound on the outer side of the solid round bar 213, both ends of the wire 22 are welded to both ends of the solid round bar 213, a second positioning portion 24 using the solid round bar 213 as the support 21 is formed, and the second positioning portion 24 is provided at the corner of the case 3 to be combined with the annular fuel element 1 near the corner of the case 3.

In some exemplary embodiments, referring to fig. 1, 3 and 5, 4 adjacent annular fuel elements 1 in two adjacent rows and two adjacent columns are arranged in a square. Among the 4 adjacent annular fuel elements 1, the outer diameter D of the annular fuel element 1, the distance P between the centers of the adjacent two annular fuel elements 1, the outer diameter D2 of the thin-walled circular tube 211 of the first positioning portion 23 located inside the first space 4 surrounded by the plurality of annular fuel elements 1, and the outer diameter dw of the wire winding 22 satisfy:

in some exemplary embodiments, referring to fig. 2, 4 and 7, the support 21 is made of a solid round bar 213, a wire 22 is spirally wound on the outer side of the solid round bar 213, both ends of the wire 22 are welded to both ends of the solid round bar 213, a second positioning portion 24 using the solid round bar 213 as the support 21 is formed, the plurality of second positioning portions 24 are combined with the plurality of annular fuel elements 1, respectively, and the plurality of annular fuel elements 1 combined with the second positioning portions 24 are arranged in a staggered manner to form the fuel bundle 11 in a regular hexagonal arrangement.

In some exemplary embodiments, referring to fig. 2, 4 and 7, two adjacent 3 annular fuel elements 1 are arranged in a regular triangle. Among the adjacent 3 annular fuel elements 1, the outer diameter D of the annular fuel element 1, the distance P between the centers of the adjacent two annular fuel elements 1, the outer diameter D3 of the solid round rod 213 of the second positioning portion 24 located inside the first space 4 surrounded by the plurality of annular fuel elements 1, and the outer diameter dw of the wire winding 22 satisfy:

in some exemplary embodiments, the wire 22 is a solid wire, with a helical winding of wire 22 of equal pitch on the support 21.

In some exemplary embodiments, referring to fig. 8, the wire 22 is a solid wire, the wire 22 is spirally wound on the support 21 at a pitch gradually decreasing in a direction from the bottom to the top of the support 21, and a plurality of welding spots are provided at contact positions of the wire 22 with the support 21 in an axial direction of the support 21.

In this embodiment, a plurality of welding points are disposed at the contact position between the wire 22 and the support member 21, or welding is performed by using a laser welding method or the like, so as to ensure that the pitch of each wire 22 spirally wound on the outside of the support member 21 is unchanged.

The fuel assembly is the core component of the reactor and generally consists of fuel elements, components connected to the core, and positioning components between the fuel elements. According to the different applicable pile types, the structural forms of the positioning components among the fuel elements are different, for example, the fuel elements in a commercial pressurized water pile are arranged in a square shape, the positioning of the fuel bundles is realized by adopting a positioning grid, the positioning components are arranged at intervals along the axial direction of the fuel assembly, the positioning components consist of strips, the radial clamping of the fuel elements is realized, and the radial and axial positioning of the fuel elements are realized, but the defects of high research and development cost and long manufacturing period are overcome. In sodium-cooled fast reactors, the fuel elements are arranged in a triangle, a wire is generally wound on the surface of the fuel element, the wire is designed to have a fixed pitch, and a plurality of contact points are formed between the fuel element and other surrounding fuel elements, so that the positioning of the fuel element is realized. And part of the research stacks adopt plate-shaped fuel elements, and the two sides of the plate-shaped fuel elements are limited by corresponding grooves, so that the fixation of the plate-shaped fuel elements is realized. It follows that the fuel assembly structure is not identical in different reactor types. Also, the positioning member structure between the fuel elements varies depending on the use requirements. Thus, the structural design of the fuel assembly should comprehensively consider the influence on the clamping capability of the fuel element, the physical and thermal hydraulic performance of the fuel element, the manufacturing period and the cost. The annular fuel assembly and the manufacturing method of the present application are provided with the above-mentioned influencing factors fully considered.

The foregoing embodiments have been provided for the purpose of illustrating the general principles of the present application and are not meant to limit the scope of the invention, but to limit the scope of the invention.

Claims (21)

1. An annular fuel assembly comprising:

a plurality of annular fuel elements (1) internally provided with fuel pellets, and a plurality of annular fuel elements (1) are arranged in an array to form a fuel rod bundle (11) in regular polygon arrangement;

a plurality of positioning portions (2), each positioning portion (2) including a support member (21) and a wire winding (22) spirally wound outside the support member (21); and

a case (3) which is wrapped outside the fuel bundle (11);

the positioning parts (2) are respectively arranged in a first space (4) surrounded by a plurality of adjacent annular fuel elements (1), and under the action of the positioning parts (2), gaps are formed between two adjacent annular fuel elements (1) so as to allow coolant entering between the annular fuel elements (1) from the bottom of the annular fuel assembly to flow along the axial direction of the annular fuel elements (1) through the gaps and generate mixing along the radial direction of the annular fuel elements (1).

2. Annular fuel assembly according to claim 1, wherein a second space (5) is formed between two adjacent annular fuel elements (1) and the cartridge body (3), the second space (5) being internally provided with a positioning portion (2).

3. The annular fuel assembly of claim 2, further comprising:

a plurality of guide tubes (6), each guide tube (6) replaces one annular fuel element (1), a plurality of guide tubes (6) are arranged with a plurality of annular fuel elements (1) in an array to form a fuel rod bundle (11) in a regular polygon arrangement, so as to allow a control rod assembly to be inserted into the guide tubes (6), and the control rod assembly or a fixed related assembly is conveniently combined with the annular fuel assembly.

4. The annular fuel assembly according to claim 2, wherein a plurality of the annular fuel elements (1) are arranged in line to form a square arrangement of fuel bundles (11), and the positioning portions (2) provided inside the first space (4) and inside the second space (5) are first positioning portions (23) with thin-walled circular tubes (211) as the supporting pieces (21);

wherein the diameter of the thin-walled circular tube (211) of the first positioning part (23) arranged in the first space (4) is larger than the diameter of the thin-walled circular tube (211) of the first positioning part (23) arranged in the second space (5).

5. The annular fuel assembly according to claim 4, wherein the side wall of the thin walled circular tube (211) is provided with at least one opening (212) and closed at the top such that coolant flowing from the bottom of the thin walled circular tube (211) into the interior of the thin walled circular tube (211) flows out through the opening (212) to form coolant flowing in a radial direction.

6. Annular fuel assembly according to claim 4, wherein a second positioning portion (24) with solid round bars (213) as the support (21) is provided inside a third space (7) formed between a corner of the cartridge (3) and the annular fuel element (1).

7. Annular fuel assembly according to claim 4, wherein 4 adjacent annular fuel elements (1) in adjacent two rows and adjacent two columns are arranged in a square,

among the 4 adjacent annular fuel elements (1), the outer diameter D of the annular fuel element (1), the distance P between the centers of the adjacent two annular fuel elements (1), the outer diameter D2 of the thin-walled circular tube (211) of the first positioning portion (23) provided inside the first space (4), and the outer diameter dw of the wire winding (22) satisfy:

such that the first positioning portion (23) arranged inside the first space (4) is in contact with or void of an adjacent annular fuel element (1).

8. Annular fuel assembly according to claim 2, wherein a plurality of said annular fuel elements (1) are arranged in staggered form forming a bundle of fuel rods (11) in regular hexagonal arrangement, said positioning portions (2) provided inside said first space (4) and inside said second space (5) being second positioning portions (24) with solid round rods (213) as said support (21).

9. Annular fuel assembly according to claim 8, wherein every two adjacent 3 annular fuel elements (1) are arranged in a regular triangle,

among the two adjacent 3 annular fuel elements (1), the outer diameter D of the annular fuel elements (1), the distance P between the centers of the adjacent two annular fuel elements (1), the outer diameter D3 of the solid round rod (213) of the second positioning portion (24) provided in the first space (4), and the outer diameter dw of the wire winding (22) satisfy:

such that the second positioning portion (24) arranged inside the first space (4) is in contact with or void of the adjacent annular fuel element (1).

10. Annular fuel assembly according to claim 1, wherein the wire winding (22) is a solid wire, the wire winding (22) being helically wound with a constant pitch on the support (21).

11. Annular fuel assembly according to claim 1, wherein the wire winding (22) is a solid wire, the wire winding (22) being helically wound on the support (21) with a pitch decreasing in a bottom-to-top direction of the support (21) to enhance radial mixing of coolant near the outlet of coolant of the annular fuel assembly.

12. A manufacturing method of an annular fuel assembly, wherein the manufacturing method is applied to the annular fuel assembly of any one of claims 1 to 11, the manufacturing method comprising:

spirally winding a wire (22) on the outer side of a support (21), both ends of the wire (22) being welded to the support (21) to form a positioning portion (2);

the positioning parts (2) are respectively combined with the annular fuel elements (1), and the annular fuel elements (1) combined with the positioning parts (2) are arrayed to form a regular polygon-arranged fuel rod bundle (11); and

a cartridge (3) is sleeved outside the fuel rod bundle (11) so as to position the edge of the fuel rod bundle (11).

13. The method of manufacturing an annular fuel assembly according to claim 12, wherein a plurality of guide tubes (6) are used instead of a plurality of the annular fuel elements (1), wherein each guide tube (6) is used instead of one of the annular fuel elements (1), such that a plurality of the guide tubes (6) are arranged in an array with a plurality of the annular fuel elements (1) to form a fuel bundle (11) in a regular polygon arrangement.

14. The manufacturing method of the annular fuel assembly according to claim 12, wherein the support member (21) is made of a thin-walled circular tube (211), a wire (22) is spirally wound outside the thin-walled circular tube (211), both ends of the wire (22) are welded to both ends of the thin-walled circular tube (211), a first positioning portion (23) using the thin-walled circular tube (211) as the support member (21) is formed, a plurality of the first positioning portions (23) are respectively combined with a plurality of the annular fuel elements (1), and a plurality of the annular fuel elements (1) combined with the first positioning portions (23) are arranged in line to form a square-arranged fuel bundle (11).

15. The method of manufacturing an annular fuel assembly according to claim 14, wherein at least one aperture is cut in a side wall of the thin walled tube (211) and top sealed.

16. The manufacturing method of the annular fuel assembly according to claim 14, wherein the support member (21) is made of a solid round rod (213), a wire winding (22) is spirally wound on the outer side of the solid round rod (213), both ends of the wire winding (22) are welded to both ends of the solid round rod (213), a second positioning portion (24) taking the solid round rod (213) as the support member (21) is formed, and the second positioning portion (24) is provided at a corner portion of the case body (3) to be combined with the annular fuel element (1) near the corner portion of the case body (3).

17. Method of manufacturing an annular fuel assembly according to claim 14, wherein 4 adjacent annular fuel elements (1) in adjacent two rows and adjacent two columns are arranged in a square,

among the 4 adjacent annular fuel elements (1), an outer diameter D of the annular fuel element (1), a distance P between centers of two adjacent annular fuel elements (1), an outer diameter D2 of the thin-walled circular tube (211) of the first positioning portion (23) located inside a first space (4) surrounded by a plurality of the annular fuel elements (1), and an outer diameter dw of the wire winding (22) satisfy:

18. the manufacturing method of the annular fuel assembly according to claim 12, wherein the support member (21) is made of a solid round rod (213), a wire winding (22) is spirally wound on the outer side of the solid round rod (213), both ends of the wire winding (22) are welded on both ends of the solid round rod (213), a second positioning portion (24) taking the solid round rod (213) as the support member (21) is formed, a plurality of the second positioning portions (24) are respectively combined with a plurality of the annular fuel elements (1), and a plurality of the annular fuel elements (1) combined with the second positioning portions (24) are arranged in a staggered manner to form a fuel bundle (11) in a regular hexagonal arrangement.

19. Method of manufacturing an annular fuel assembly according to claim 18, wherein two adjacent 3 annular fuel elements (1) are arranged in a regular triangle,

among the two adjacent 3 annular fuel elements (1), an outer diameter D of the annular fuel elements (1), a distance P between centers of the adjacent two annular fuel elements (1), an outer diameter D3 of the solid round rod (213) of the second positioning portion (24) located inside the first space (4) surrounded by the plurality of annular fuel elements (1), and an outer diameter dw of the wire winding (22) satisfy:

20. the method of manufacturing an annular fuel assembly according to claim 12, wherein the wire winding (22) is a solid wire, the wire winding (22) being helically wound with a uniform pitch on the support (21).

21. The manufacturing method of an annular fuel assembly according to claim 12, wherein the wire (22) is a solid wire, the wire (22) is spirally wound on the support (21) at a pitch gradually decreasing in a direction from bottom to top of the support (21), and a plurality of welding spots are provided at contact positions of the wire (22) and the support (21) in an axial direction of the support (21).