Heat pipe micro-reactor, fuel assembly positioning structure of heat pipe micro-reactor and fuel assembly mounting method of heat pipe micro-reactor

Abstract

A heat pipe micro-reactor fuel assembly positioning structure comprises a first end plate and a second end plate which are oppositely and fixedly arranged, and a mounting space for a fuel assembly is provided between the first end plate and the second end plate. The first end plate is rigidly connected with the fuel assembly, the second end plate is elastically connected with the fuel assembly through an elastic connecting piece, the elastic connecting piece applies axial pressure to the fuel assembly and allows the fuel assembly to axially move at the second end, and the elastic connecting piece provides circumferential limiting for the fuel assembly. The heat pipe micro-reactor fuel assembly positioning structure can effectively absorb the axial displacement or deformation of the fuel assembly while providing stable support for the fuel assembly, and improves the reliability in the transportation process. The invention further provides a heat pipe micro-reactor fuel assembly mounting method and a heat pipe micro-reactor.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power, and in particular relates to a heat pipe micro-pile and a fuel assembly positioning structure and a fuel assembly installation method thereof. Background Art

[0002] As a new type of reactor, the core structure of the heat pipe micro-reactor is quite different from that of the traditional pressurized water reactor or gas-cooled reactor. The heat pipe micro-reactor adopts a solid core and does not have a primary circuit. Instead, it uses heat pipes to conduct the fission heat generated by the fuel to the outside of the reactor. Due to the omission of the flowing cooling medium and the complex primary circuit, the heat pipe micro-reactor has the advantages of high inherent safety, small size, simple structure, and easy and rapid deployment. Mobile nuclear power devices have also become one of the most promising applications of heat pipe micro-reactors. Since the heat pipe micro-reactor adopts a fully solid core, the fuel assembly in the core cannot be fixed by the positioning structure in the traditional pressurized water reactor. Considering the needs of mobile deployment of the heat pipe micro-reactor, it is also necessary to meet the fuel assembly's ability to withstand adverse conditions such as transportation vibration. Therefore, providing a fuel assembly positioning structure with high reliability has positive significance for improving the safety of the heat pipe micro-reactor. Summary of the invention

[0003] The purpose of the present invention is to provide a heat pipe micro-reactor fuel assembly positioning structure to provide vibration buffering for the fuel assembly. The present invention also provides a heat pipe micro-reactor fuel assembly installation method and a heat pipe micro-reactor.

[0004] According to an embodiment of one aspect of the present invention, there is provided a heat pipe micro-reactor fuel assembly positioning structure, comprising a first end and a second end, wherein the first end comprises a first end plate, the second end comprises a second end plate, and the first end plate and the second end plate are relatively fixedly arranged; an installation space is formed between the first end plate and the second end plate to allow the fuel assembly to extend axially between the first end plate and the second end plate; one end of the fuel assembly is rigidly connected to the first end plate, and the other end is elastically connected to the second end plate via an elastic connection component, the elastic connection component applies axial pressure to the fuel assembly and allows the other end to move axially within a certain range relative to the second end plate, and the elastic connection component provides circumferential limitation for the other end.

[0005] The heat pipe micro-reactor fuel assembly positioning structure can provide a certain degree of axial displacement freedom for the fuel assembly through an elastic connection assembly, thereby providing accommodation space and buffering for the fuel assembly to grow under irradiation or to move during transportation.

[0006] Furthermore, in some embodiments, the elastic connection assembly includes a rigid connection portion and a spring, the rigid connection portion is fixedly connected to the fuel assembly, and the spring is connected between the rigid connection portion and the second end plate.

[0007] Furthermore, in some embodiments, a stepped hole is provided on the second end plate, and the stepped hole includes a first hole segment and a second hole segment, the first hole segment matches the end of the fuel assembly, and the second hole segment matches the rigid connection portion to allow the spring to be compressed by the fuel assembly and the rigid connection portion in the first hole segment.

[0008] Furthermore, in some embodiments, the elastic connection assembly is arranged at the axial position of the fuel assembly, the center of the elastic connection assembly is set as a hollow shaft, and the second end plate is provided with a through hole connected to the hollow shaft to allow the heat pipe of the fuel assembly to pass through.

[0009] Furthermore, in some embodiments, the elastic connection assembly is configured in plurality, and the plurality of elastic connection assemblies are arranged around the axis of the fuel assembly, and the second end plate is provided with a through hole to allow the heat pipe of the fuel assembly to pass through.

[0010] Furthermore, in some embodiments, the first end plate is provided with a boss or a recessed hole matching with the end of the fuel assembly to achieve a rigid connection.

[0011] Furthermore, in some embodiments, fastening bolts are provided on the first end plate, and the fastening bolts connect the first end plate and the fuel assembly.

[0012] Furthermore, in some embodiments, the heat pipe micro-stack fuel assembly positioning structure is manufactured using a combination of one or more of 718 alloy, X-750 alloy, 600 alloy, 625 alloy and 690 alloy.

[0013] According to an embodiment of another aspect of the present invention, there is provided a method for installing a heat pipe micro-reactor fuel assembly, comprising the following steps: providing a positioning structure, wherein the positioning structure adopts the heat pipe micro-reactor fuel assembly positioning structure provided in any of the aforementioned embodiments; providing a fuel assembly substrate, fuel rods, end cover plates and heat pipes; loading the fuel rods into the substrate, and welding the end cover plates at both ends of the substrate; connecting the end cover plates to the first end plate and the second end plate respectively, so that the end cover plates are rigidly connected to the first end plate and elastically connected to the second end plate; inserting the heat pipe into the substrate to complete the installation.

[0014] According to another aspect of the present invention, there is provided a heat pipe micro-stack, comprising a fuel assembly and a fuel assembly positioning structure, wherein the fuel assembly is mounted on the fuel assembly positioning structure, and the fuel assembly positioning structure adopts the heat pipe micro-stack fuel assembly positioning structure provided in any of the aforementioned embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1This is a schematic structural diagram of the heat pipe micro-reactor fuel assembly installation state in one embodiment;

[0016] Figure 2 This is a schematic diagram of the first end installation structure of a fuel assembly in one embodiment;

[0017] Figure 3 This is a schematic diagram of the structure of the first end plate of a fuel assembly in one embodiment;

[0018] Figure 4 This is a schematic diagram of the second end installation structure of a fuel assembly in one embodiment;

[0019] Figure 5 This is a schematic diagram of the structure of the second end plate of a fuel assembly in one embodiment;

[0020] Figure 6 This is a schematic diagram of the matching structure between the rigid connection part and the second hole segment in one embodiment;

[0021] Figure 7 It is a schematic diagram of the installation structure of the first end of the fuel assembly in another embodiment;

[0022] Figure 8 It is a schematic diagram of the second end installation structure of the fuel assembly in another embodiment.

[0023] The purpose of the above drawings is to explain the present invention in detail in conjunction with the drawings so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. For the sake of simplicity, the above drawings only schematically illustrate the structures related to the technical features of the present invention, and do not strictly illustrate the complete structure and all details in accordance with the actual proportion. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0025] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0026] In the description of this article, unless otherwise clearly specified and limited, the technical terms "installed", "connected", "connected" and the like should be understood in a broad sense, which can be a movable connection, a fixed connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0027] In the description of this document, terms indicating orientation or positional relationships, such as "up", "down", "left", "right", "horizontal", "vertical", "height", "length", and "width", are intended to accurately describe the embodiments and simplify the description, but are not intended to limit the parts or structures involved to have a specific orientation, be installed or operate in a specific orientation, and should not be construed as a limitation on the embodiments in this document.

[0028] In the description of this article, the terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating relative importance or limiting the quantity, specific order or primary and secondary relationship of the described technical features. In the description of this article, the meaning of "plurality" is at least two.

[0029] In the field of nuclear power, conventional pressurized water reactors, gas-cooled reactors and other reactor types use flowing cooling media to remove the heat generated by the core fuel assemblies. They have complex structures and high inherent safety requirements. As a new type of reactor, the heat pipe micro-reactor uses a solid core and uses the matrix of the fuel assembly as a heat transfer medium. The heat pipe removes the fission heat generated by the fuel in the core. Since the cooling medium flow channel of the first circuit is eliminated and the main pump and other structures are not required, the heat pipe micro-reactor has better inherent safety. At the same time, it also has the advantages of silent operation, small size and light weight, and has significant advantages in mobile transportation and flexible deployment. Therefore, the fuel assembly of the heat pipe micro-reactor needs to consider the influence of factors such as transportation vibration during the installation and positioning process. The fuel assembly positioning structure used in the traditional pressurized water reactor type cannot meet the needs of the heat pipe micro-reactor.

[0030] In order to solve the above problems, an embodiment of one aspect of the present invention provides a heat pipe micro-reactor fuel assembly positioning structure.

[0031] like Figure 1 As shown, the fuel assembly 2 of the heat pipe micro-stack is fixed horizontally between the first end plate 1 and the second end plate 3. Figure 3 Each fuel assembly includes a hexagonal matrix, multiple fuel rods and heat pipes are inserted into the matrix along the axial direction, and the fuel rods are arranged around the heat pipes. Multiple fuel assemblies 2 are arranged in parallel to form a solid core of the heat pipe micro-stack. The heat pipe passes through one end of the fuel assembly 2, and the heat released by the core is conducted to an external thermoelectric conversion device through the sodium contained in the heat pipe to generate electricity.

[0032] The first end plate 1 and the second end plate 3 are relatively fixedly arranged, and while providing vertical support for the fuel assembly 2, they also need to provide axial buffering for the fuel assembly so that the fuel assembly can withstand the dimensional changes caused by irradiation growth and the axial vibration during transportation. Among them, the first end plate 1 and the fuel assembly 2 are rigidly connected; the second end plate 3 and the fuel assembly 2 are elastically connected through an elastic connection assembly, which applies axial pressure to the fuel assembly 2 and allows the fuel assembly 2 to move axially within a certain range to absorb the deformation caused by irradiation growth or the axial vibration during transportation. At the same time, the elastic connection assembly provides circumferential limitation for the fuel assembly 2 to prevent the fuel assembly 2 from rolling circumferentially.

[0033] In a preferred embodiment, the structure of the first end plate 1 is as follows Figure 2 As shown, the first end mounting structure of the fuel assembly 2 mounted on the first end plate 1 is as shown in Figure 3 As shown. A first cover plate 21 is provided at the end of the fuel assembly 2. The first cover plate 21 seals the fuel rods and heat pipes inside the hexagonal base of the fuel assembly 2. A spline 22 is protruding from the first cover plate 21. A fastening screw hole 23 is provided at the center of the spline 22. A mounting hole 11 matching the spline 22 is provided on the first end plate 1, so that the spline 22 can be inserted into the mounting hole 11 to be fixed. The mounting hole 11 is set as a through hole to allow a bolt to pass through the through hole and connect to the fastening screw hole 23, thereby fastening the first end plate 1 and the fuel assembly 2 together to achieve a rigid connection.

[0034] The connection method between the fuel assembly 2 and the second end plate 3 is as follows: Figure 4 As shown, the corresponding second end mounting structure of the fuel assembly 2 mounted on the second end plate 3 is as shown in Figure 5 As shown. A second cover plate 24 is provided at the end of the fuel assembly 2, and the second cover plate 24 is welded to the base of the fuel assembly 2 to enclose the fuel rods in the base. A spline 22 is protrudingly provided on the second cover plate 24, and a through hole is provided in the center of the spline 22 for the heat pipe to pass through. A through hole 34 is provided on the second end plate 3 to allow the spline 22 to be installed. In a preferred embodiment, the through hole 34 is arranged as a stepped hole, and the side close to the first end plate 1 is a first hole section, the shape of the first hole section matches the spline 22, and the axial length is longer than the spline 22. The part of the first hole section with an axial length longer than the spline 22 provides an axial movement space for the fuel assembly 2 at the second end plate 3; the side away from the first end plate 1 is a second hole section, and the second hole section allows the heat pipe to pass through. Combined with Figure 6 The fuel assembly 2 is connected to the second end plate 3 through an elastic connection assembly, which includes a spring 31 and a rigid connection member 32. The rigid connection member 32 is connected to the second end plate 3 through a bearing 35 installed in the second hole segment; the spring 31 is arranged between the spline 22 and the rigid connection member 32 and is accommodated in the first hole segment.

[0035] In this way, the fuel assembly is rigidly connected to the first end plate 1 and elastically connected to the second end plate 3 in the axial direction. The mounting hole 11 and the through hole 34 cooperate with the spline 22 at the end of the fuel assembly 2, and the spline 22 is used to support and position the fuel assembly 2 in the vertical direction, and to limit the fuel assembly 2 in the circumferential direction to prevent the fuel assembly 2 from rolling in the circumferential direction; the spring 31 is compressed to axially press the fuel assembly 2, and when the fuel assembly 2 undergoes irradiation growth or axial movement, the spring 31 can be further compressed to enable the fuel assembly 2 to move axially in a small range within the range of the first hole section, so as to absorb deformation and buffer, thereby improving the reliability of the fuel assembly during transportation.

[0036] When the fuel assembly positioning structure provided in the above embodiment is adopted, the installation method of the fuel assembly 2 is as follows:

[0037] First, install the fuel rods in the base of the fuel assembly 2, weld the first cover plate 21 and the second cover plate 24 at both ends, and seal the fuel rods in the base; next, insert the spline 22 of the first cover plate 21 into the mounting hole 11 of the first end plate 1; install the elastic connection assembly in the through hole 34 of the second end plate 3, insert the spline 22 of the second cover plate 24 into the through hole 34, compress the spring 31 and tighten the spline 22 in the axial direction; install the bolts in the mounting hole 11 to achieve the rigid connection between the fuel assembly 2 and the first end plate 1; finally, insert the heat pipe from the through hole 34 through the bearing 35, the rigid connector 32, the spring 31 and the spline 22 into the base of the fuel assembly 2 to complete the installation. The assembled fuel assembly should be able to withstand a maximum axial acceleration of 4g under transportation and operating conditions.

[0038] The heat pipe micro-stack using the fuel assembly positioning structure provided in the above embodiment can achieve good positioning and installation of the fuel assembly. While providing stable vertical support, it provides stable positioning through a rigid connection at one end in the axial direction, and effectively absorbs and buffers axial vibrations through an elastic connection at the other end, thereby improving the reliability of the heat pipe micro-stack during transportation.

[0039] In other embodiments, the specific form of the heat pipe micro-stack fuel assembly positioning structure can be adaptively adjusted, for example, the bolts on the first end plate 1 can be replaced by hollow bolts, so that the heat pipe passes through one side of the first end plate 1; the spring 31 can also be replaced by a hydraulic or pneumatic elastic mechanism, etc. In some embodiments, a structural form can also be adopted in which a concave hole is provided on the first cover plate and / or the second cover plate of the fuel assembly 2, and a boss matching the concave hole is provided on the first end plate 1 and / or the second end plate 3 for connection.

[0040] In some embodiments, multiple connection structures may be provided at one or both ends of the fuel assembly 2 to replace a single spline 22 and an elastic connection assembly, so as to achieve the effect of dispersing the load and improving the connection flexibility.

[0041] In another embodiment, the first cover plate 21' of the fuel assembly 2 has a structure as follows: Figure 7 As shown, the spline 22 is replaced by a hexagonal boss 22', and the hexagonal boss 22' is provided with 7 fastening screw holes 23'. Correspondingly, the mounting hole 11 on the first end plate 1 is also replaced by a hexagonal recessed hole matching the hexagonal boss 22', and a through hole corresponding to the fastening screw hole 23' is provided at the bottom of the recessed hole to allow the bolt to pass through and be tightened in the fastening screw hole 23'. The structure of the second cover plate 24' of the fuel assembly 2 is as follows Figure 8 As shown, the number of elastic connection components is changed from one to six, each of which is provided with a small-sized spring 31' and a rigid connection member 32', and the connection structure of the second end plate is also adaptively adjusted accordingly, while the position of the elastic connection components is arranged to avoid the position where the heat pipe passes through. This structure can disperse the fixed load of the fuel assembly 2 and further improve the connection flexibility between the fuel assembly 2 and the first end plate 1 and the second end plate 3.

[0042] In different embodiments, the heat pipe micro-reactor fuel assembly positioning structure can be manufactured using a combination of one or more of 718 alloy, X-750 alloy, 600 alloy, 625 alloy and 690 alloy. For example, the entire structure can be manufactured using the same alloy material; or, according to the design and manufacturing requirements of different parts, a part of the structure can be manufactured using one alloy, and other structures can be manufactured using one or more other grades of alloys. When using multiple alloys for manufacturing, parts with independent structures can be manufactured using one alloy, or different grades of alloys can be used to manufacture different parts of the parts and then combined together by welding or the like.

[0043] The purpose of the above embodiments is to further explain the present invention in detail in conjunction with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, the optimization or equivalent replacement of the part structure or method steps involved, and the combination of implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

Claims

1. A heat pipe micro-reactor fuel assembly positioning structure, characterized in that: It includes a first end and a second end, the first end includes a first end plate, the second end includes a second end plate, and the first end plate and the second end plate are relatively fixedly arranged; an installation space is formed between the first end plate and the second end plate to allow the fuel assembly to extend axially between the first end plate and the second end plate; one end of the fuel assembly is rigidly connected to the first end plate, and the other end is elastically connected to the second end plate through an elastic connection component, the elastic connection component applies axial pressure to the fuel assembly and allows the other end to move axially within a certain range relative to the second end plate, and the elastic connection component provides circumferential limitation for the other end.

2. The heat pipe micro-reactor fuel assembly positioning structure according to claim 1, characterized in that: The elastic connection assembly includes a rigid connection part and a spring. The rigid connection part is fixedly connected to the fuel assembly, and the spring is connected between the rigid connection part and the second end plate.

3. The heat pipe micro-reactor fuel assembly positioning structure according to claim 2, characterized in that: A stepped hole is provided on the second end plate, and the stepped hole includes a first hole segment and a second hole segment, wherein the first hole segment matches the end of the fuel assembly, and the second hole segment matches the rigid connection portion to allow the spring to be compressed by the fuel assembly and the rigid connection portion in the first hole segment.

4. The heat pipe micro-reactor fuel assembly positioning structure according to claim 2 or 3, characterized in that: The elastic connection assembly is arranged at the axial center position of the fuel assembly, the center of the elastic connection assembly is arranged as a hollow shaft, and the second end plate is arranged with a through hole communicating with the hollow shaft to allow the heat pipe of the fuel assembly to pass through.

5. The heat pipe micro-reactor fuel assembly positioning structure according to claim 2 or 3, characterized in that: The elastic connection components are configured in multiple numbers, and the multiple elastic connection components are arranged around the axis of the fuel assembly. The second end plate is provided with a through hole to allow the heat pipe of the fuel assembly to pass through.

6. The heat pipe micro-reactor fuel assembly positioning structure according to claim 1, characterized in that: The first end plate is provided with a boss or a recessed hole matching with the end of the fuel assembly to achieve a rigid connection.

7. The heat pipe micro-reactor fuel assembly positioning structure according to claim 1 or 6, characterized in that: The first end plate is provided with fastening bolts, and the fastening bolts connect the first end plate and the fuel assembly.

8. The heat pipe micro-reactor fuel assembly positioning structure according to claim 1, 2 or 3, characterized in that: The heat pipe micro-stack fuel assembly positioning structure is manufactured by using a combination of one or more of 718 alloy, X-750 alloy, 600 alloy, 625 alloy and 690 alloy.

9. A method for installing a heat pipe micro-reactor fuel assembly, characterized in that: The following steps are involved: Providing a positioning structure, wherein the positioning structure adopts the heat pipe micro-reactor fuel assembly positioning structure as described in any one of claims 1 to 8; providing a fuel assembly matrix, a fuel rod, an end cover plate and a heat pipe; Installing the fuel rods into the substrate and welding the end covers at both ends of the substrate; Connecting the end cover plate to the first end plate and the second end plate respectively, so that the end cover plate is rigidly connected to the first end plate and elastically connected to the second end plate; The heat pipe is inserted into the base to complete the installation.

10. A heat pipe micro-reactor, comprising a fuel assembly, characterized in that: The heat pipe micro-stack further comprises a fuel assembly positioning structure, the fuel assembly is mounted on the fuel assembly positioning structure, and the fuel assembly positioning structure adopts the heat pipe micro-stack fuel assembly positioning structure as described in any one of claims 1 to 8.

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