Reactor core structure with flattened temperature and heat pipe micro-reactor

Abstract

A flattened temperature reactor core structure comprises a fuel assembly, and the fuel assembly comprises a base body, a fuel rod and a heat pipe. Wherein a plurality of mounting holes extending in the axial direction of the base body are formed in the axial section of the base body, the mounting holes are arranged in multiple parallel columns in the first direction, the mounting holes in the second direction forming a 60-degree included angle with the first direction are also arranged in columns, 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 in the first direction and the second direction; and in the fuel rods arranged along the edge of the base body, one of two adjacent fuel rods is replaced by a vacant position. And the plurality of fuel assemblies are densely laid to form a reactor core structure. According to the reactor core structure, temperature flattening can be effectively achieved, local overheating is avoided, and therefore the efficiency and reliability of the heat pipe micro-reactor are improved. The invention also provides a heat pipe micro-stack.

Description

Technical Field

[0001] The 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 micro-reactors have low power consumption, small size, simplified structure, flexible deployment, and can be prefabricated in factories, transportable devices, and self-adjustable in operation. They can be adapted to special application scenarios such as space, oceans, remote areas, and mobile power supply. Heat pipe micro-reactors usually adopt a passive all-solid core design. The core heat is exported to the thermodynamic / thermoelectric conversion system through heat pipes, and the core structure does not require a complex liquid cooling circuit. However, correspondingly, since the heat pipe micro-reactor adopts a pure solid core and there is no flow heat conduction of the cooling medium, the core temperature distribution is more uneven than that of the pressurized water reactor, and it is easy to form local hot spots with poor heat dissipation in the core, which limits the increase in reactor power and affects the safety of reactor operation. Therefore, providing a core structure with flattened temperature and improving the uniformity of the solid core temperature distribution has a high practical value for improving the safety performance of heat pipe micro-reactors. 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 flattened temperature core structure, comprising a fuel assembly, the fuel assembly comprising a substrate, a fuel rod and a heat pipe; the substrate is provided with a plurality of mounting holes extending axially along the substrate, the mounting holes in the axial cross section of the substrate are arranged in a first direction as a plurality of parallel rows, the mounting holes in adjacent rows are arranged in a staggered manner, one of the mounting holes in the adjacent row is distributed on the mid-vertical line between two adjacent mounting holes in any row, and two adjacent mounting holes in the same row are arranged at 60° relative to the mounting hole in the adjacent row located on the mid-vertical line between the 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 inserted into 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 position; a plurality of the fuel assemblies are closely laid to form the core structure.

[0005] When the matrix is ​​closely packed to form the core structure, the fuel rods in the edge area of ​​each matrix are affected by the fuel rods in the adjacent matrix, which is prone to poor heat dissipation and local overheating. On the one hand, this will cause the temperature difference between the heat pipes to reduce the power generation efficiency, and on the other hand, the uneven local temperature distribution for a long time will cause safety hazards to the long-term temperature operation of the reactor. By replacing the fuel rods in the overheating area with empty spaces, 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 space is set as a measurement channel, and the measurement channel includes a temperature measurement channel or a neutron measurement channel. During the operation of the reactor, the internal temperature needs to be measured in real time. By using the vacant space to arrange the temperature measurement channel, on the one hand, the temperature measurement at the location of the vacant space can accurately reflect the temperature state in the reactor, and on the other hand, the structural characteristics of the core can be fully utilized, making the core structure more compact.

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

[0008] Further, 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] Further, 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 empty spaces; 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 empty spaces 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 another embodiment of the present invention, there is provided a heat pipe micro-rice, comprising a core structure, wherein the core structure adopts the flattening temperature core structure provided in any of the aforementioned embodiments.

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

[0015] Figure 1 A schematic diagram of a cross-sectional structure of a heat pipe micro-stack in one embodiment;

[0016] Figure 2 This is a schematic diagram of the cross-sectional structure of a fuel assembly in one embodiment;

[0017] Figure 3 This is a schematic diagram of the basic unit structure of a fuel rod-heat pipe in a fuel assembly in one embodiment;

[0018] Figure 4 It is a schematic diagram of the structure of the local overheating area in a pair of ratios;

[0019] Figure 5a A pair of proportional temperature distribution cloud diagrams of the fuel assembly cross section;

[0020] Figure 5b A cloud diagram of the temperature distribution of a cross section of a fuel assembly in one embodiment;

[0021] Figure 6 A schematic diagram of a cross-sectional structure of a fuel assembly in another embodiment;

[0022] Figure 7 FIG. 4 is a schematic diagram of the cross-sectional structure of a fuel assembly in another embodiment.

[0023] The purpose of the above drawings is to explain the present invention in detail 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 follow the actual scale to draw the complete structure and all details. 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 order to solve the problem of uneven heat distribution in the core of a heat pipe micro-reactor and eliminate local hot spots in the reactor core, an embodiment of the present invention provides a core structure for flattening the temperature. The core structure is applied to Figure 1 In the heat pipe micro-reactor shown. The heat pipe micro-reactor includes a core structure composed of multiple fuel assemblies 1, a drum 2 and a reflective layer 3 are arranged circumferentially on the outer periphery of the core structure, and a shell structure 4 is closed at the outermost layer. At the same time, a hole for inserting a shutdown control rod 5 is reserved in the center of the core structure. The shutdown control rod 5 is movably installed in the reactor. When the shutdown control rod 5 is inserted into the core along the axial direction of the heat pipe micro-reactor, it can absorb neutrons to stop the reactor. In different embodiments, the shutdown control rod 5 can be set to one or more, and the shutdown control rod 5 and the drum 2 jointly perform power adjustment and emergency shutdown control on the reactor.

[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 substrate 6, a fuel rod 7 and a heat pipe 8, wherein the substrate 6 supports and fixes the fuel rod 7 and the heat pipe 8, and is in a regular hexagon as a whole. A plurality of mounting holes are arranged on the axial section of the substrate 6, and the mounting holes extend along the axial direction of the substrate 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°), and one mounting hole in the adjacent column is distributed on the perpendicular midline of two adjacent mounting holes in any column, as shown in FIG. Figure 2As shown, on the perpendicular midline of the centers of the mounting holes 7a and 7b in the same horizontal row, there is a mounting hole 7c in an adjacent horizontal row, and the mounting holes 7a and 7b form an angle of 60° 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 distances between the centers and edges of the mounting holes arranged along the edges of the hexagon are the same. The fuel rods 7 and the heat pipes 8 are inserted into the mounting holes along the length direction. Along the arrangement direction (i.e., any direction shown by arrow a, 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 hexagonal shape as shown in FIG. Figure 3 In the structural unit shown, three heat pipes 8 are adjacently arranged around each fuel rod 7 to take away the heat generated by the fuel rod 7 .

[0031] However, if Figure 4 As shown in FIG. 1 , under such an arrangement, when the fuel assemblies 1 are closely laid, there is only one heat pipe 8 around the fuel rods 7 in the vertex 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 FIG. Figure 5a As shown, the temperature of the fuel rods 7 and the matrix 6 in the visible area 10 is significantly higher than that in other areas, resulting in an obvious uneven temperature distribution. This will not only cause the temperature of the heat pipes 8 in the adjacent area 10 to be higher than that of other heat pipes 8, affecting the power generation efficiency, but also long-term local overheating will cause the core structure to bear additional temperature stress. Once the heat pipes 8 in the adjacent area 10 leak or fail, resulting in a decrease in cooling capacity, temperature runaway is likely to occur in the area 10, which may induce an accident in severe cases. In other embodiments, when there are two continuous fuel rods 7 in the middle of the edge of the matrix 6, a clustering area of ​​the fuel rods 7 arranged in 2×2 will also be formed, resulting in poor local heat dissipation. Replacing two of the fuel rods 7 with vacancies 9 can effectively solve the problem of local overheating.

[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 vacancy 9 is set as a measurement channel. In different embodiments, the measurement channel can be configured as a measurement channel for measuring the temperature or neutrons in 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 the reactor power in real time. Through this setting, the simulation results of the temperature distribution cloud map in the cross section of the fuel assembly 1 are as follows: Figure 5bAs shown, it can be seen that the temperature distributions of the heat pipes 8 and the matrix 6 are uniform, eliminating the phenomenon of local overheating. Further, since temperature measurement channels are required to be arranged in the core itself to monitor the temperature during the continuous operation of the reactor, setting the vacant positions 9 as temperature measurement channels can make full use of the existing structure of the core, avoiding the additional setting of separate temperature measurement structures, making the overall core structure more compact, and avoiding affecting the working efficiency of the reactor on the basis of accurately measuring the core temperature.

[0033] In different embodiments, according to the reactor size and the structural design of the fuel assembly 1, the number and arrangement form of the mounting holes in a single fuel assembly 1 can be different. For example, Figure 2 as shown, there are 5 mounting holes arranged along the hexagon edge, and a total of 61 holes are provided in a single fuel assembly 1. In another embodiment, for example, Figure 6 as shown, there are 6 mounting holes arranged along the hexagon edge, and a total of 91 holes are provided in a single fuel assembly 1. According to the different numbers of mounting holes in the matrix 6, the vacant positions 9 can be set at different positions. In the preferred embodiment, when the number N of the mounting holes arranged along the hexagon edge is odd, the mounting holes near the hexagon vertex positions are set as the vacant positions 9, and then the other fuel rods 7 arranged along the edge are set according to the principle that one of the adjacent two fuel rods 7 is replaced by the vacant position 9. In some other embodiments, when N is even, the mounting holes near the hexagon vertex positions in the matrix are set as the fuel rods 7, and then the other fuel rods 7 arranged along the edge are arranged according to the principle that one of the adjacent two fuel rods 7 is replaced by the vacant position 9, and the set positions of the vacant positions 9 are centrosymmetric with respect to the center of the hexagon, so that the positions of the fuel rods 7 and the vacant positions 9 on the edge can be staggered from each other when the fuel assemblies 1 are arranged in a close-packed manner, further flattening the temperature, as Figure 6 shown.

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

[0035] In some other embodiments, the fuel rods 7 and the heat pipes 8 can also be set to have different diameters. For example, Figure 7 as shown, where the diameter D1 of the heat pipe 8 and the diameter D2 of the fuel rod 7 should satisfy 1 < D1:D2 ≤ 2. In such a core structure, the fuel rods 7 and the heat pipes 8 in a single fuel assembly 1 also satisfy the structural unit formed by 3 heat pipes 8 arranged adjacent to each fuel rod 7. The mounting holes with the same aperture are arranged at equal intervals (that is, the center distance between adjacent mounting holes with the same aperture is equal). Similarly, in this structure, the setting of the vacant positions 9 is the same as that in the embodiment where the fuel rods 7 and the heat pipes 8 have the same diameter described above. In such as Figure 7 In the fuel assembly 1 shown with 5 mounting holes arranged along the edge of the hexagon, the hexagonal vertex position is set as an empty position, and the middle one of the 5 mounting holes arranged along the edge of the hexagon is set as a heat pipe 8. The solution of using large heat pipes 8 and small fuel rods 7 can increase the heat transfer area and reduce the local heat transfer thermal resistance, especially when the local heat pipe 8 fails, the core temperature can be further flattened.

[0036] In a preferred embodiment, in order to ensure the overall efficiency of the fuel assembly 1, the size of the matrix 6 should satisfy the following requirements: the distance between a pair of parallel opposite sides of the hexagon is between.

[0037] In some embodiments, the base 6 may also be configured as other shapes, such as an equilateral triangle.

[0038] The above-mentioned embodiments can effectively realize the temperature flattening inside the core of the heat pipe micro-reactor, can reduce the thermal stress on the core due to uneven temperature distribution, and is conducive to increasing the operating temperature of the reactor and thus improving the power generation efficiency. It can also further improve the accident resistance of the heat pipe micro-reactor in the event 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 explain the present invention in detail through specific embodiments in combination with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope disclosed by the present invention, the optimization or equivalent replacement of the part structure involved, and the combination of the implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

Claims

1. A flattening temperature core structure, characterized in that: comprising a fuel assembly, the fuel assembly comprising a matrix, a fuel rod and a heat pipe; The substrate is provided with a plurality of mounting holes extending along the axial direction of the substrate. The mounting holes are arranged into a plurality of parallel rows in the axial section of the substrate along the first direction. The mounting holes in adjacent rows are arranged in a staggered manner. One mounting hole in the adjacent row is distributed on the mid-perpendicular line between two adjacent mounting holes in any row. Two adjacent mounting holes in the same row form an angle of 60° with respect to the mounting holes located on the mid-perpendicular line of the two mounting holes in the adjacent row, so that the plurality of mounting holes are also arranged into a plurality of parallel rows in the second direction forming an angle of 60° 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, and the heat pipes are arranged between the fuel rods at intervals. Two fuel rods are arranged between every two adjacent heat pipes along 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 an empty position. A plurality of the fuel assemblies are closely laid out to form the core structure.

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

3. The flattened temperature core structure according to claim 1 or 2, characterized in that: The fuel rod and the heat pipe 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 substrate closest to any side.

7. The flattened temperature core structure according to claim 1 or 2, characterized in that: The substrate 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 substrate, when N is an odd number, the mounting holes in the substrate close to the vertices of the hexagon are set as empty spaces; 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 empty spaces 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 arranged in the heat pipe micro-rice.

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