Core structure with flattened temperature and heat pipe microstack

Abstract

The application discloses a core structure of temperature flattening, which comprises fuel assemblies, the fuel assemblies comprising a base body, fuel rods and heat pipes. The axial section of the base body is provided with a plurality of mounting holes extending along the axial direction of the base body, the mounting holes are arranged into parallel columns along a first direction, the mounting holes are also arranged into columns along a second direction at an angle of 60 degrees with the first direction, and the mounting holes arranged along the edge of the base body have the same minimum distance with the edge. Two fuel rods are arranged between every two heat pipes along the first direction and the second direction; among the fuel rods arranged along the edge of the base body, one of the two adjacent fuel rods is replaced by a vacancy. A plurality of fuel assemblies are densely arranged to form the core structure. The core structure can effectively realize temperature flattening and avoid local overheating, thereby improving the efficiency and reliability of the heat pipe micro reactor. The application further provides a heat pipe micro reactor.

Description

Technical Field

[0001] The present invention belongs to the field of nuclear power, and in particular relates to a flattened temperature core structure and a heat pipe micro-reactor. Background Art

[0002] Heat pipe microreactors offer low power consumption, a small size, a simplified structure, and flexible deployment. They can be prefabricated in factories, transported, and self-regulate during operation, making them suitable for specialized applications such as space, oceans, remote areas, and mobile power supply. Heat pipe microreactors typically utilize a passive, all-solid-state core design. Core heat is transferred to a thermodynamic / thermoelectric conversion system via heat pipes, eliminating the need for complex liquid cooling circuits. However, since heat pipe microreactors utilize a purely solid-state core and lack the flow of a coolant, the core temperature distribution is more uneven than in pressurized water reactors (PWRs). This can easily lead to the formation of localized hot spots within the core, limiting reactor power increases and compromising reactor safety. Therefore, providing a flattened core structure to improve the uniformity of solid-state core temperature distribution is of great practical value in enhancing the safety performance of heat pipe microreactors. Summary of the Invention

[0003] The purpose of the present invention is to provide a core structure with flattened temperature to improve the temperature uniformity of the reactor core. The present invention also provides a heat pipe micro-reactor.

[0004] According to an embodiment of one aspect of the present invention, there is provided a flattening temperature core structure, comprising a fuel assembly, the fuel assembly comprising a substrate, fuel rods and heat pipes; the substrate is provided with a plurality of mounting holes extending axially along the substrate, the mounting holes in an axial cross-section of the substrate are arranged in a first direction into a plurality of parallel rows, the mounting holes in adjacent rows are staggered, one mounting hole in an adjacent row is distributed on a perpendicular midline between two adjacent mounting holes in any row, and two adjacent mounting holes in the same row are at an angle of 60° relative to a mounting hole in an adjacent row located on a perpendicular midline between two mounting holes. Angle, so that the multiple mounting holes are also arranged into multiple parallel rows in a second direction that is 60° angled with the first direction; the centers of the mounting holes arranged along the edge of the substrate have the same minimum distance from the edge of the substrate; the fuel rods and the heat pipes are passed through the mounting holes, and the heat pipes are arranged at intervals between the fuel rods; two fuel rods are arranged between every two adjacent heat pipes along the first direction and the second direction, and among the fuel rods arranged along the edge of the substrate, one of the two adjacent fuel rods is replaced by an empty space; a plurality of fuel assemblies are closely laid to form the core structure.

[0005] When the core structure is formed by closely packed substrates, the fuel rods at the edge of each substrate are affected by the fuel rods in adjacent substrates, which can lead to poor heat dissipation and local overheating. This, on the one hand, causes temperature differences between heat pipes, reducing power generation efficiency, and on the other hand, the uneven temperature distribution in these areas over a long period of time can pose a safety hazard to the long-term temperature operation of the reactor. By replacing the fuel rods in the overheating area with vacant spaces, the local overheating can be eliminated, the temperature can be effectively flattened, and the accident tolerance of the core can be improved.

[0006] Furthermore, in some embodiments, the vacant spaces are configured as measurement channels, including temperature measurement channels or neutron measurement channels. During reactor operation, real-time internal temperature measurement is required. Using vacant spaces to arrange temperature measurement channels not only accurately reflects the temperature state within the reactor, but also fully utilizes the core's structural features, making the core structure more compact.

[0007] Furthermore, in some embodiments, the fuel rods and the heat pipes have the same diameter, and the mounting holes are arranged at equal intervals.

[0008] Furthermore, in some embodiments, the base is configured as a regular hexagon, and the distance between a pair of parallel opposite sides of the base is Wherein N is the number of the mounting holes in a row at the edge of the substrate closest to any side, and D is the diameter of the fuel rod and the heat pipe.

[0009] Furthermore, in some embodiments, the ratio of the diameter D1 of the heat pipe to the diameter D2 of the fuel rod satisfies 1 <D 1: D2≤2, the mounting holes with the same aperture are arranged at equal intervals.

[0010] Furthermore, in some embodiments, the base is configured as a regular hexagon, and the distance between a pair of parallel opposite sides of the base is Wherein N is the number of the mounting holes in a row at the edge of the base closest to any side.

[0011] Furthermore, in some embodiments, the substrate is configured as a regular hexagon, and for the number N of the mounting holes in a row closest to the edge of one side of the substrate, when N is an odd number, the mounting holes in the substrate close to the vertices of the hexagon are set as vacancies; when N is an even number, the mounting holes in the substrate close to the vertices of the hexagon are set as fuel rods, and the vacancies are arranged in a centrally symmetrical manner.

[0012] Furthermore, in some embodiments, the number of mounting holes of the base is 61 holes or 91 holes.

[0013] According to an embodiment of the aspect of the application, a heat pipe micro reactor is provided, comprising a core structure, wherein the core structure is a flattened temperature core structure as provided in any of the preceding embodiments.

[0014] Further, in some embodiments, at least one shutdown control rod is movably arranged in the core structure. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Schematic view of a cross section of a heat pipe micro reactor according to an embodiment;

[0016] Figure 2 Schematic view of a cross section of a fuel assembly according to an embodiment;

[0017] Figure 3 Schematic view of a fuel rod - heat pipe basic unit structure in a fuel assembly according to an embodiment;

[0018] Figure 4 Schematic view of a local hot spot structure in a comparative example;

[0019] Figure 5a Cross section temperature distribution map of a fuel assembly in a comparative example;

[0020] Figure 5b Cross section temperature distribution map of a fuel assembly according to an embodiment;

[0021] Figure 6 Schematic view of a cross section of a fuel assembly according to another embodiment;

[0022] Figure 7 Schematic view of a cross section of a fuel assembly according to yet another embodiment.

[0023] The above-described drawings serve to provide a detailed description of the present application in order for those skilled in the art to be able to understand the technical idea of the present application, and are not intended to limit the present application. For the sake of brevity, the above-described drawings only schematically depict structures related to the technical features of the present application, and do not depict complete structures and all details in strict accordance with actual proportions. DETAILED DESCRIPTION

[0024] The present application will be further described by way of specific embodiments with reference to the accompanying drawings.

[0025] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of one another. Those skilled in the art will recognize that the embodiments of the present application can be combined with other embodiments in order to provide yet other embodiments.

[0026] In the description herein, unless otherwise specified or limited, the technical terms "installed," "connected," and "connected" should be understood broadly, and may refer to movable connections, fixed connections, or integration. Those skilled in the art will understand the specific meanings of these terms in the embodiments of this application based on 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 having a specific orientation, being installed or operated in a specific orientation, and should not be understood as limiting the embodiments in this document.

[0028] In the description herein, terms such as "first" and "second" are used only to distinguish different objects and should not be understood to indicate relative importance or to limit the quantity, specific order, or primary and secondary relationship of the described technical features. In the description herein, "plurality" means at least two.

[0029] In order to solve the problem of uneven heat distribution in the heat pipe micro-reactor core and eliminate local hot spots in the reactor core, an embodiment of the present invention provides a core structure with flattened temperature, which is applied to Figure 1 The heat pipe micro-reactor shown in FIG. includes a core structure composed of multiple fuel assemblies 1. A rotating drum 2 and a reflector layer 3 are circumferentially arranged around the core structure. A shell structure 4 forms a closed outer layer. A central hole for a shutdown control rod 5 is reserved. This control rod 5 is movably mounted within the reactor. When inserted axially into the core, it absorbs neutrons and shuts down the reactor. In various embodiments, one or more shutdown control rods 5 can be provided. Together with the rotating drum 2, these rods 5 control the reactor power and perform emergency shutdown control.

[0030] The core structure is formed by a plurality of hexagonal fuel assemblies 1 arranged closely together. In one embodiment, the structure of the fuel assembly 1 is as follows: Figure 2 As shown, it includes a base 6, fuel rods 7 and heat pipes 8, wherein the base 6 supports and fixes the fuel rods 7 and the heat pipes 8, and is in the shape of a regular hexagon as a whole. A plurality of mounting holes are provided on the axial section of the base 6. These mounting holes extend along the axial direction of the base 6. The mounting holes are arranged in an array with equal intervals (i.e., the distances between the centers of adjacent mounting holes are equal) along the direction parallel to the side length of the hexagon (as shown by arrows a, b, and c, wherein arrow a and arrow b, and arrow b and arrow c form an angle of 60°). In any row, a mounting hole in the adjacent row is distributed on the perpendicular bisector between two adjacent mounting holes. Figure 2As shown, there is a mounting hole 7c in an adjacent horizontal row on the perpendicular midline of the center of the mounting holes 7a and 7b in the same horizontal row, and the mounting holes 7a and 7b form a 60° angle relative to the mounting hole 7c. That is, the center lines of the mounting holes distributed in the form of 7a, 7b, and 7c form an equilateral triangle. The minimum distance between the center and edge of the mounting holes arranged along each edge of the hexagon is the same. The fuel rods 7 and the heat pipes 8 are passed through the mounting holes along the length direction. Along the arrangement direction (i.e., any direction shown by arrow a or arrow b or arrow c), two fuel rods 7 are arranged between every two heat pipes 8, which makes the fuel rods 7 and the heat pipes 8 form a equilateral triangle. Figure 3 In the structural unit shown, three heat pipes 8 are adjacently arranged around each fuel rod 7 to remove the heat generated by the fuel rod 7 .

[0031] However, if Figure 4 As shown in Figure 1, under such an arrangement, when the fuel assemblies 1 are densely packed, there is only one heat pipe 8 around the fuel rods 7 in the top corner area, and the adjacent positions of other fuel assemblies 1 are all fuel rods 7, which leads to poor heat dissipation of the fuel rods in area 10. The temperature distribution cloud diagram obtained by heat transfer analysis simulation in the cross section of the fuel assembly 1 is shown in Figure 1. Figure 5a As shown, the temperature of the fuel rods 7 and the matrix 6 in the visible region 10 is significantly higher than that in other regions, resulting in a significant uneven temperature distribution. This will not only cause the temperature of the heat pipes 8 in the adjacent region 10 to be higher than that of other heat pipes 8, affecting the power generation efficiency, but long-term local overheating will also cause the core structure to bear additional temperature stress. Once the heat pipes 8 in the adjacent region 10 leak or fail, resulting in a decrease in cooling capacity, temperature runaway is likely to occur in the region 10, which may induce an accident in severe cases. In other embodiments, when there are two consecutive fuel rods 7 in the middle of the edge of the matrix 6, a clustered area of ​​fuel rods 7 arranged in a 2×2 pattern will also be formed, resulting in poor local heat dissipation. Replacing two of the fuel rods 7 with vacancies 9 can effectively solve the local overheating problem.

[0032] Therefore, if Figure 2 As shown, among the heat pipes 8 arranged along the hexagonal edge of the base 6, one of the two adjacent heat pipes is replaced by a vacancy 9 (i.e. Figure 2 The vacant space 9 is configured as a measurement channel. In different embodiments, the measurement channel can be configured to measure the temperature or neutrons within the core, and is used to arrange temperature sensors or neutron measurement sensors to monitor the temperature state of the heat pipe micro-reactor core or reactor power in real time. With this configuration, the simulation results of the temperature distribution cloud map within the cross section of the fuel assembly 1 are as follows: Figure 5bAs shown, the temperature distribution of each heat pipe 8 and the base 6 is uniform, eliminating local overheating. Furthermore, since the core itself requires a temperature measurement channel to monitor the temperature during continuous operation of the reactor, setting up the vacant space 9 as a temperature measurement channel can fully utilize the existing structure of the core, avoiding the need for an additional separate temperature measurement structure, making the core structure more compact, and avoiding any impact on reactor efficiency while accurately measuring the core temperature.

[0033] In different embodiments, depending on the reactor size and the structural design of the fuel assembly 1, the mounting holes in a single fuel assembly 1 may have different numbers and arrangements, such as Figure 2 As shown, there are 5 mounting holes arranged along the edge of the hexagon, and a single fuel assembly 1 is provided with 61 holes. In another embodiment, as shown in FIG. Figure 6 As shown, there are 6 mounting holes arranged along the edge of the hexagon, and a single fuel assembly 1 is provided with a total of 91 holes. Depending on the number of mounting holes in the matrix 6, the vacancies 9 can be set at different positions. In a preferred embodiment, when the number N of mounting holes arranged along the edge of the hexagon is an odd number, the mounting holes close to the top corners of the hexagon are set as vacancies 9, and then the other fuel rods 7 arranged along the edge are arranged according to the principle of replacing one of the two adjacent fuel rods 7 with a vacancies 9. In other embodiments, when N is an even number, the mounting holes close to the top corners of the hexagon in the matrix are set as fuel rods 7, and then the other fuel rods 7 arranged along the edge are arranged according to the principle of replacing one of the two adjacent fuel rods 7 with a vacancies 9, and the setting positions of the vacancies 9 are distributed symmetrically relative to the center of the hexagon, so that when the fuel assembly 1 is densely laid, the positions of the fuel rods 7 and the vacancies 9 can be staggered with each other, further flattening the temperature, as shown in FIG. Figure 6 shown.

[0034] In a preferred embodiment, in order to ensure the overall efficiency of the fuel assembly 1, the size of the matrix 6 and the diameter D of the fuel rod 7 and the heat pipe 8 should satisfy the following requirements: the distance between a pair of parallel opposite sides of the hexagon is between.

[0035] In other embodiments, the fuel rods 7 and the heat pipes 8 may also be configured to have different diameters, such as Figure 7 As shown, the diameter D1 of the heat pipe 8 and the diameter D2 of the fuel rod 7 should satisfy 1 <D1:D2≤2。在这样的堆芯结构中,单个燃料组件1中的燃料棒7与热管8同样满足每条燃料棒7周围相邻设置有3条热管8所形成的结构单元。具有相同孔径的安装孔以等间距排布(即具有相同孔径的相邻安装孔间圆心距离相等)。同样的,在该结构中,空位9的设置与前述燃料棒7与热管8具有相同直径的实施例具有相同的设置方式。在如 Figure 7 In the fuel assembly 1 shown in which five mounting holes are arranged along the edges of the hexagon, the position of the top corner of the hexagon is provided with an empty position, and the middle one of the five mounting holes arranged along the edges of the hexagon is provided with the heat pipe 8. The scheme of using the large heat pipe 8 and the small fuel rod 7 can increase the heat transfer area and reduce the local heat transfer thermal resistance, and in particular, when the local heat pipe 8 fails, the core temperature can be further flattened.

[0036] In the preferred embodiment, in order to ensure the overall efficiency of the fuel assembly 1, the size of the base body 6 should meet: the distance between the parallel opposite sides of the hexagon is between 0.5D and 1.5D.

[0037] In some embodiments, the base body 6 can also be provided in other shapes, such as a regular triangle.

[0038] The above embodiments can effectively realize the temperature flattening inside the heat pipe micro reactor core, can reduce the thermal stress of the core due to uneven temperature distribution, and is also conducive to improving the working temperature of the reactor to improve the power generation efficiency, and can further improve the anti-accident ability of the heat pipe micro reactor in the case of partial heat pipe failure, and improve the overall reliability of the heat pipe micro reactor.

[0039] The purpose of the above embodiments is to further illustrate the present application through specific embodiments combined with the drawings, so that those skilled in the art can understand the technical concept of the present application. Within the scope disclosed in the present application, the structures of the parts involved are optimized or equivalently replaced, and the embodiments in different embodiments are combined without structural and principle conflicts, which all fall within the protection scope of the present application.​

Claims

1. A flattening temperature core structure, characterized in that: comprising a fuel assembly, said fuel assembly comprising a matrix, a fuel rod, and a heat pipe; The substrate is provided with a plurality of mounting holes extending axially along the substrate. In an axial cross-section of the substrate, the mounting holes are arranged in a plurality of parallel rows along a first direction. The mounting holes in adjacent rows are staggered. One mounting hole in the adjacent row is located on a perpendicular midline between two adjacent mounting holes in any row. Two adjacent mounting holes in the same row form a 60° angle with respect to the mounting holes located on a perpendicular midline between two mounting holes in the adjacent row, so that the plurality of mounting holes are also arranged in a plurality of parallel rows in a second direction forming a 60° angle with the first direction. The centers of the mounting holes arranged along the edge of the substrate have the same minimum distance from the edge of the substrate. The fuel rods and the heat pipes are inserted into the mounting holes, with the heat pipes spaced between the fuel rods. Two fuel rods are disposed between every two adjacent heat pipes in the first direction and the second direction. Among the fuel rods arranged along the edge of the substrate, one of the two adjacent fuel rods is replaced by a vacant position. A plurality of the fuel assemblies are closely arranged to form the core structure.

2. The flattening temperature core structure according to claim 1, characterized in that: The vacancy is configured as a measurement channel, and the measurement channel includes a temperature measurement channel or a neutron measurement channel.

3. The flattening temperature core structure according to claim 1 or 2, characterized in that: The fuel rods and the heat pipes have the same diameter, and the mounting holes are arranged at equal intervals.

4. The flattened temperature core structure according to claim 3, characterized in that: The base is configured as a regular hexagon, and the distance between a pair of parallel opposite sides of the base is Wherein, N is the number of the mounting holes in a row closest to any edge of the substrate, and D is the diameter of the fuel rod and the heat pipe.

5. The flattened temperature core structure according to claim 1 or 2, characterized in that: The ratio of the diameter D1 of the heat pipe to the diameter D2 of the fuel rod satisfies 1 <D 1: D2≤2, the mounting holes with the same aperture are arranged at equal intervals.

6. The flattened temperature core structure according to claim 5, characterized in that: The base is configured as a regular hexagon, and the distance between a pair of parallel opposite sides of the base is Wherein N is the number of the mounting holes in a row at the edge of the base closest to any side.

7. The flattened temperature core structure according to claim 1 or 2, characterized in that: The base is configured as a regular hexagon. For the number N of the mounting holes in a row closest to the edge of one side of the base, when N is an odd number, the mounting holes in the base near the vertices of the hexagon are set as vacancies; when N is an even number, the mounting holes in the base near the vertices of the hexagon are set as fuel rods, and the vacancies are arranged in a centrally symmetrical manner.

8. The flattened temperature core structure according to claim 7, characterized in that: The number of mounting holes of the base is 61 holes or 91 holes.

9. A heat pipe micro-reactor, comprising a core structure, characterized in that: The core structure adopts the flattening temperature core structure as claimed in any one of claims 1 to 8.

10. The heat pipe micro-stack according to claim 9, characterized in that: At least one shutdown control rod is movably provided in the heat pipe micro-stack.

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