Fuel assembly and reactor

Abstract

The embodiment of the invention relates to a reactor fuel element and an assembly thereof, in particular to a fuel assembly and a reactor. The fuel assembly comprises a shell and at least one plate type fuel set. The shell forms an accommodating space for allowing a coolant to flow; and each plate-type fuel group is arranged in the accommodating space. Each plate-type fuel set comprises a plurality of plate-type fuels and a plurality of first heat exchange plates. The plurality of plate-type fuels are arranged in parallel; each first heat exchange plate is arranged between two adjacent plate-type fuels, and each first heat exchange plate and each adjacent plate-type fuel jointly form a plurality of flow channels for a coolant to flow. According to the embodiment of the invention, the first heat exchange plate is arranged, so that a plurality of runners are formed between the first heat exchange plate and each corresponding plate-type fuel, and the cooling effect of the coolant on the plate-type fuel is improved. And moreover, the first heat exchange plates can prevent two adjacent plate-type fuels from expanding, so that a cooling flow channel between the two adjacent plate-type fuels is narrowed, and the cooling effect on the plate-type fuels is influenced.

Description

Technical Field

[0001] Embodiments of this application relate to reactor fuel elements and their assembly, and particularly to a fuel assembly and reactor. Background Technology

[0002] This section provides background information relevant to this application only and does not necessarily constitute prior art.

[0003] Micro research reactors are typically low-power reactors used for research purposes, and a small number of micro research reactors have already been built in China.

[0004] However, current micro research reactors still have many limitations. Summary of the Invention

[0005] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0006] In a first aspect, embodiments of this application provide a fuel assembly comprising: a housing and at least one set of plate fuel assemblies; the housing forming a receiving space for coolant flow; each set of plate fuel assemblies being disposed within the receiving space. Each set of plate fuel assemblies includes a plurality of plate fuels and a plurality of first heat exchange plates. The plurality of plate fuels are arranged parallel to each other; each first heat exchange plate is disposed between two adjacent plate fuels, and each first heat exchange plate is configured to, together with each adjacent plate fuel, form a plurality of flow channels for coolant flow.

[0007] The embodiments of this application, by placing a first heat exchange plate between two adjacent plate fuels, create multiple flow channels between the first heat exchange plate and each plate fuel. This allows some of the heat generated by the plate fuels to be carried away by the coolant flowing over the surface of the plate fuels in each flow channel, while the remaining heat is transferred to the first heat exchange plate and then carried away by the coolant flowing over its surface, thereby improving the cooling effect of the coolant on the plate fuels. Furthermore, the placement of the first heat exchange plate between two adjacent plate fuels enhances the stability of the flow channel structure, preventing expansion of adjacent plate fuels or deformation due to coolant flow, structural stress, or other factors. This prevents the cross-section of the cooling flow channel between adjacent plate fuels from narrowing, which would negatively impact the cooling effect. This stable flow channel structure also helps to further increase the coolant flow rate, thus contributing to an increase in the reactor's power density.

[0008] In a second aspect, embodiments of this application provide a reactor comprising: a reactor core as provided in the first aspect of this application, a radial reflector layer, a plurality of control drums, and a neutron beam device; the radial reflector layer is disposed on the radially outer side of the reactor core, and the radially inner surface of the radial reflector layer matches the radially outer surface of the reactor core; the plurality of control drums are disposed in the radial reflector layer; the neutron beam device is disposed in the radial reflector layer for reducing neutron reflection in that direction; wherein the radial reflector layer and the reactor core each form at least one irradiation channel.

[0009] These and other advantages of this application will become more apparent from the following detailed description of preferred embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0010] To further illustrate the above and other advantages and features of this application, the specific embodiments of this application will be described in more detail below with reference to the accompanying drawings. The drawings, together with the following detailed description, are included in and form a part of this specification. Elements having the same function and structure are indicated by the same reference numerals. It should be understood that these drawings only depict typical examples of this application and should not be considered as limiting the scope of this application.

[0011] Figure 1 This is a schematic diagram of the structure of a fuel assembly according to an embodiment of this application; Figure 2 This is a partially exploded view of a fuel assembly according to an embodiment of this application; Figure 3 This is a schematic diagram of the structure of a reactor according to an embodiment of this application.

[0012] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding.

[0013] Explanation of reference numerals in the attached figures: 1. Fuel assembly; 10. Plate fuel assembly; 11. Shell; 110. Retaining space; 12. Plate fuel; 121. Fuel core; 122. Cladding; 13. First heat exchange plate; 130. Arc groove; 1301. Flow channel; 131. First surface; 132. Second surface; 14. Second heat exchange plate; 140. Arc groove; 1401. Flow channel; 141. Fourth surface; 142. Third surface; 2. Core; 20. In-core irradiation channel; 3. Radial reflector layer; 30. Reflector layer irradiation channel; 4. Control drum; 5. Neutron beam device. Detailed Implementation

[0014] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.

[0015] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0016] It should be noted that, unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning as understood by a person with ordinary skills in the field to which this application pertains.

[0017] In the description of the embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0018] Currently, the heat flux of ordinary research reactors can only reach... The current level of heat flux in research reactors is insufficient to meet the flux requirements for applications such as BNCT and isotope production. To increase the heat flux of research reactors, it is necessary to increase the core power density, which essentially means improving the core's cooling capacity, i.e., the cooling capacity of the fuel assemblies. Therefore, improving the cooling capacity of the fuel assemblies has become an urgent problem to be solved in research reactors.

[0019] Based on this, embodiments of this application provide a fuel assembly to improve the cooling capacity of the fuel assembly.

[0020] In some embodiments, see Figure 1 , Figure 1 This is a schematic diagram of a fuel assembly according to an embodiment of this application. The fuel assembly 1 of this embodiment may include: a housing 11 and at least one set of plate fuel assemblies 10; the housing 11 forms a receiving space 110 for coolant flow; each set of plate fuel assemblies 10 is disposed in the receiving space 110. Each set of plate fuel assemblies 10 includes a plurality of plate fuels 12 and a plurality of first heat exchange plates 13. The plurality of plate fuels 12 are arranged parallel to each other; each first heat exchange plate 13 is disposed between two adjacent plate fuels 12, and each first heat exchange plate 13 is configured to, together with each adjacent plate fuel 12, form a plurality of flow channels 1301 for coolant flow.

[0021] The embodiments of this application, by setting a first heat exchange plate 13 between two adjacent plate fuels 12, form multiple flow channels 1301 between the first heat exchange plate 13 and each plate fuel 12. This allows some of the heat generated by the plate fuels 12 to be carried away by the coolant flowing over the surface of the plate fuels 12 in each flow channel 1301, while the remaining heat is transferred to the first heat exchange plate 13 and then carried away by the coolant flowing over its surface. This improves the cooling effect of the coolant on the plate fuels 12 and enhances the cooling capacity of the fuel assembly 1. Furthermore, the placement of the first heat exchange plate 13 between two adjacent plate fuels 12 improves the stability of the flow channel structure, preventing expansion of adjacent plate fuels 12 or deformation of the plate fuels 12 due to coolant flow, structural stress, or other factors. This prevents the cross-section of the cooling flow channel between adjacent plate fuels 12 from narrowing, which would affect the cooling effect. This stable flow channel structure also helps to further increase the coolant flow rate, thereby contributing to an increase in the reactor's power density.

[0022] Because the fuel assembly 1 in the embodiments of this application has a high cooling capacity, it is beneficial to improve the core cooling capacity, increase the core power density, and increase the neutron flux of the reactor.

[0023] In some embodiments, each plate fuel pack 10 may further include two second heat exchange plates 14; each second heat exchange plate 14 is disposed on the outermost side of each plate fuel pack 10 to form multiple flow channels 1401 for coolant flow together with the outermost plate fuel 12. In such an embodiment, for the outermost plate fuel 12, the second heat exchange plate 14 is also provided to form multiple flow channels 1401, thereby forming multiple flow channels on both sides of each plate fuel 12, improving the cooling effect of the coolant on the plate fuel 12, and preventing the cross-section of the cooling flow channels from narrowing due to the expansion of the plate fuel 12, which would affect the cooling effect on the plate fuel 12.

[0024] The second heat exchange plate 14 can face the inner wall of the shell 11 or another set of plate fuel 10. The second heat exchange plate 14 mainly relies on the flow channel 1401 formed between it and the plate fuel 12 for heat exchange. In order to improve the heat exchange effect of the second heat exchange plate 14, the cross-sectional area of ​​the flow channel 1401 can be made larger than the cross-sectional area of ​​the flow channel 1301 of the first heat exchange plate 13.

[0025] In some embodiments, see Figure 2 , Figure 2This is a partially exploded view of a fuel assembly 1 according to an embodiment of this application. The first heat exchange plate 13 may include a first surface 131 and a second surface 132 disposed opposite to each other. The first surface 131 and the second surface 132 respectively form a plurality of arcuate grooves 130, and each arcuate groove 130 forms a flow channel 1301 with a corresponding plate fuel 12. In this embodiment, the shape of the first heat exchange plate 13 is advantageous in increasing its heat exchange area with the coolant, while shortening the heat transfer path between the first heat exchange plate 13 and the plate fuel 12, thereby improving cooling capacity.

[0026] In some embodiments, the plurality of arc-shaped grooves 130 may be arranged at equal intervals to facilitate uniform heat exchange of the plate fuel 12.

[0027] In some embodiments, see Figure 2 The arc groove 130 formed on the first surface 131 and the arc groove 130 formed on the second surface 132 can be staggered, thereby reducing the thickness of the first heat exchange plate 13, improving the heat exchange efficiency, and reducing the space occupied by the first heat exchange plate 13, thereby increasing the amount of plate fuel 12.

[0028] In some embodiments, see Figure 2 The second heat exchange plate 14 may include a third surface 142 and a fourth surface 141 disposed opposite to each other. The third surface 142 forms a plurality of arc-shaped grooves 140 and faces the plate fuel 12; the fourth surface 141 is planar. In such an embodiment, the third surface 142 forming a plurality of arc-shaped grooves 140 can cooperate with the plate fuel 12 to form a flow channel 1401 for coolant water to flow through, and the planar fourth surface 141 facilitates the arrangement of each group of plate fuel 10 within the receiving space 110.

[0029] The above-mentioned structural design of the first heat exchange plate 13 and the second heat exchange plate 14 can ensure improved heat exchange efficiency while also having strong mechanical strength and structural stability. On the other hand, through the efficient heat conduction of the first heat exchange plate 13 and the second heat exchange plate 14 themselves and the design of the arc groove, the heat transfer path is shortened, thereby achieving enhanced heat exchange.

[0030] Furthermore, when fuel assembly 1 is applied to a reactor with water as the coolant, the first heat exchange plate 13 and the second heat exchange plate 14 occupy part of the water space, which makes the reactor core in a sub-slowed state, which is beneficial for realizing neutron applications with a wide energy spectrum, such as BNCT, which requires ultrathermal neutrons.

[0031] In some embodiments, see Figure 2 The cross-sections of the arc grooves 130 and 140 can be semi-circular, which can maximize the cross-sectional area of ​​the flow channels 1301 and 1401 while ensuring the stability of the structure.

[0032] In some embodiments, the thickness of the plate fuel 12 can be 1-3 mm.

[0033] In some embodiments, the radius of the semicircle can be 0.5-2 mm, which is more conducive to ensuring the stability of the structure while maximizing the cross-sectional area of ​​the flow channel 1301 and the flow channel 1401, and avoiding excessive flow resistance.

[0034] In some embodiments, the size of the arcuate groove 140 of the second heat exchange plate 14 is larger than the size of the arcuate groove 130 of the first heat exchange plate 13. Since no coolant flows over the fourth surface 141 of the second heat exchange plate 14, by making the size of the arcuate groove 140 of the second heat exchange plate 14 larger, it is beneficial to use the coolant flowing through the arcuate groove 140 to cool the entire second heat exchange plate 14, thereby improving the overall heat exchange efficiency of the fuel assembly 1.

[0035] In some embodiments, the first heat exchange plate 13 and the second heat exchange plate 14 can contact the plate fuel 12 without being fixedly connected, so as to facilitate the assembly of the fuel assembly 1.

[0036] The flow channels 1301 formed by the first surface 131 and the plate fuel 12 of the first heat exchange plate 13 and the second surface 132 formed by the plate fuel 12 are not interconnected; the flow channels 1301 formed by the same surface of the first heat exchange plate 13 in contact with the same plate fuel 12 are basically not interconnected; the flow channels 1401 formed by the same surface of the second heat exchange plate 14 in contact with the same plate fuel 12 are basically not interconnected. An inlet and an outlet are respectively provided at both ends of the axial direction of the fuel assembly 1. The coolant enters each flow channel through the lower inlet of the fuel assembly 1, flows through the plate fuel 12, and then flows out of the fuel assembly 1 through the upper outlet.

[0037] In some embodiments, see Figure 2 The first heat exchange plate 13 and the second heat exchange plate 14 can be made of aluminum. Because the aluminum substrate has a certain strength, the heat exchange plates made of aluminum are not easily deformed after fuel expansion, preventing narrowing of the flow channels and thus ensuring that the thermal conductivity is not affected. This ensures that the coolant water can flow smoothly through the channels to carry away the heat from the plate fuel 12. At the same time, the aluminum substrate itself has highly efficient thermal conductivity, which helps to enhance the cooling capacity of the heat exchange plates. Furthermore, because the aluminum substrate occupies some of the space occupied by the water, it allows the reactor core to be in a less slowed-down state, which is beneficial for achieving a broad-spectrum neutron application.

[0038] In some embodiments, both the first heat exchange plate 13 and the second heat exchange plate 14 can be manufactured by chemical etching.

[0039] In some embodiments, the plate fuel 12 may be composed of a casing 122 and a fuel core 121 disposed within the casing 122.

[0040] In some embodiments, the casing 122 may be made of stainless steel to contain the radioactivity of the fuel.

[0041] In some embodiments, the fuel core 121 can be made of uranium-zirconium hydrogen. By using uranium-zirconium hydrogen as the fuel core 121, the power load following characteristics are better, while the risk of supercriticality is eliminated, greatly reducing safety review and regulatory costs.

[0042] Uranium-zirconium hydrogen alloy can be obtained by hydrogen percolation into a uranium-zirconium alloy under certain temperature and pressure. Its composition is UZrHx, where U is low-enriched uranium and x = 1.6-1.8.

[0043] In some embodiments, the housing 11 may be in the shape of a hexagonal prism.

[0044] In some embodiments, see Figure 1 and Figure 2 The cross-section of the accommodating space 110 can be a regular hexagon composed of three rhomboid regions. The fuel assembly 1 includes three sets of plate fuel groups 10, each set of plate fuel groups 10 being disposed in one of the rhomboid regions. In this embodiment, it is advantageous to assemble multiple fuel assemblies 1 into a core active region with near-circular boundaries, thereby reducing neutron leakage. Since the three sets of plate fuel groups 10 are disposed in one rhomboid region, it is beneficial to achieve uniform fuel distribution within the core active region.

[0045] In such an embodiment, for each plate fuel pack 10, the plate fuel 12 and the first heat exchange plate 13 are stacked alternately, and two second heat exchange plates 14 are respectively set at both ends of the diamond-shaped area along the stacking direction, which can increase the heat exchange area and improve the cooling capacity while ensuring the stability of the structure.

[0046] In some embodiments, see Figure 1 The plate fuel 12 in two adjacent rhomboid regions can form an angle of 120°, which is beneficial to the uniform distribution of fuel in the core active region.

[0047] In some embodiments, the three plate fuel packs 10 are assembled into a hexagon after being rotated by 0°, 120° and 240° respectively, thereby being integrally assembled with the housing 11 to form a single fuel assembly 1.

[0048] Embodiments of this application also provide a reactor. See [link to related document]. Figure 3 , Figure 3This is a schematic diagram of a reactor according to an embodiment of this application. The reactor may include: a reactor core 2, a radial reflector layer 3, multiple control drums 4, and a neutron beam device 5. The reactor core 2 may be composed of fuel assemblies 1 provided in any embodiment of this application; the radial reflector layer 3 is disposed on the radially outer side of the reactor core 2, and the radially inner surface of the radial reflector layer 3 matches the radially outer surface of the reactor core 2; multiple control drums 4 are disposed in the radial reflector layer 3; the neutron beam device 5 is disposed in the radial reflector layer 3 to reduce neutron reflection in this direction; wherein the radial reflector layer 3 and the reactor core 2 each form at least one irradiation channel.

[0049] The reactor provided in the embodiments of this application uses fuel assembly 1 provided in any embodiment of this application to form the reactor core 2. Since the fuel assembly 1 has a high cooling capacity, it is beneficial to increase the reactor core power density, thereby increasing the neutron flux of the reactor.

[0050] Furthermore, the embodiments of this application, by setting multiple control drums 4 within the reflective layer, can avoid the absorption of neutrons within the reactor core caused by setting control rods within the reactor core; by setting a radial reflective layer 3, leakage outside the reactor core can be reduced, thereby concentrating the neutron flux in the reactor core 2 region by simultaneously reducing absorption within the reactor core and leakage outside the reactor core, which is beneficial to improving the neutron flux level inside the reactor core 2; by setting a neutron beam device 5 in the radial direction of the reflective layer, neutron reflection in this direction can be reduced, neutron leakage can be increased, and a horizontal neutron beam can be extracted, thereby providing an interface for neutron applications such as BNCT; by forming irradiation channels 30 in the reflective layer and irradiation channels 20 within the reactor core, it can be used to produce isotopes.

[0051] The increased neutron flux of the reactor in this application not only expands the applications of the reactor device but also improves the efficiency of its use.

[0052] In some embodiments, the in-pile irradiation channel 20 may hold an irradiation target for the production of isotopes.

[0053] In some embodiments, the shape of the in-pile irradiation channel 20 is the same as the shape of the fuel assembly 1.

[0054] In some embodiments, the radial reflective layer 3 may include a container and diamond microparticles filled within the container. In related technologies, the material of the radial reflective layer 3 is typically graphite, beryllium oxide, stainless steel, water, etc. The embodiments of this application, by filling the container with diamond microparticles to form a diamond reflective layer, achieve a superior reflective effect compared to related materials in the prior art, thereby improving the neutron reflection performance of the reflective layer.

[0055] In some embodiments, diamond microparticles can be filled using a vibration compaction method.

[0056] In some embodiments, the coolant operating temperature range within the reactor can be 40°C-50°C, using a forced circulation method.

[0057] In some embodiments, the power of core 2 is 500kW-1MW, and the undisturbed heat flux of the irradiation channels is up to [amount missing]. This is higher than existing microfluidic levels. Currently, the related technologies can achieve this. Research reactors with higher flux typically have power levels in the range of ten megawatts to hundreds of megawatts, resulting in high overall costs and making them difficult to widely adopt. The embodiments in this application have lower power and lower fuel and construction costs.

[0058] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0059] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A fuel assembly characterized by, It comprises: a shell and at least one set of plate fuel assemblies; the shell forms a containing space for coolant to flow; each set of the plate fuel assemblies is arranged in the containing space, and each set of the plate fuel assemblies comprises a plurality of plate fuels and a plurality of first heat exchange plates; the plurality of plate fuels are arranged in parallel with each other; each first heat exchange plate is arranged between two adjacent plate fuels, and each first heat exchange plate is arranged to form a plurality of flow channels for coolant to flow together with each plate fuel adjacent thereto.

2. The fuel assembly of claim 1, wherein, The first heat exchange plate comprises a first surface and a second surface arranged oppositely, and the first surface and the second surface form a plurality of arc-shaped grooves respectively, and each arc-shaped groove forms a flow channel with the corresponding plate fuel.

3. The fuel assembly of claim 2, wherein, The arc-shaped grooves formed by the first surface and the arc-shaped grooves formed by the second surface are staggered with each other.

4. The fuel assembly of claim 1, wherein, Each set of the plate fuel assemblies further comprises two second heat exchange plates; each second heat exchange plate is arranged at the outermost side of each set of the plate fuel assemblies to form a plurality of flow channels for coolant to flow together with the plate fuel at the outermost side.

5. The fuel assembly of claim 4, wherein, The second heat exchange plate comprises a third surface and a fourth surface arranged oppositely, the third surface forms a plurality of arc-shaped grooves, and the third surface faces the plate fuel; the fourth surface is a plane.

6. The fuel assembly according to claim 2 or 5, characterized in that The cross section of the arc-shaped groove is semicircular.

7. The fuel assembly according to any one of claims 1-6, wherein, The cross section of the containing space is a regular hexagon composed of three rhombic regions, the fuel assembly comprises three sets of plate fuel assemblies, and each set of the plate fuel assemblies is arranged in one rhombic region.

8. The fuel assembly according to claim 7, characterized in that The plate fuels in two adjacent rhombic regions form an included angle of 120°.

9. The fuel assembly according to claim 4, wherein The first heat exchange plate and the second heat exchange plate are aluminum-based.

10. A reactor characterized by, It comprises: a core composed of a plurality of fuel assemblies according to any one of claims 1-9; a radial reflection layer arranged radially outside the core, and a radially inner surface of the radial reflection layer matches a radially outer surface of the core; a plurality of control drums arranged in the radial reflection layer; a neutron beam device arranged in the radial reflection layer for reducing the reflection of neutrons in this direction; wherein the radial reflection layer and the core form at least one irradiation channel respectively.

11. The reactor of claim 10, wherein, The radial reflection layer comprises a container and diamond microparticles filled in the container.

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