Title - STORAGE AND TRANSPORT CONTAINER FOR SPENT FUEL

Abstract

A container for storing and transporting spent fuel is presented, characterized in that the container includes a casing, a tank, and a protective cover, wherein the tank is located inside the casing, fuel compartments for storing the spent fuel are placed within the tank, the tank is provided with a heat-conducting structure to conduct heat away from the fuel compartments, and the protective cover is arranged at both ends of the casing to seal it. The container for storing and transporting spent fuel has good heat conduction performance.

Description

The present invention relates to the technical field of the nuclear industry, in particular to a container for the storage and transport of spent fuel. Background of the technique Spent fuel from a nuclear power plant must be kept safe during storage and transport. It must be ensured that all spent fuel is contained within the containment vessel, both under normal conditions and in the event of an accident, and that the containment, shielding, and subcritical functions of the vessel are maintained and guaranteed. Therefore, when designing the containment vessel, to ensure the safety of all spent fuel contained within it in the event of an impact, fall, or fire, a suitable container structure must be considered and selected. With existing technology, the device for storing spent fuel capable of safe transport has a low performance of i 1745369 of 27 heat conduction and also presents complex processing and manufacturing problems, low critical performance and high costs, among others. Summary The technical problem to be solved by the present invention is to provide a storage and transport container for spent fuel, which has good heat conduction performance, to address the deficiencies already mentioned in the prior art. To solve the problem, the present invention is characterized by the following technical scheme: A container for storing and transporting spent fuel, comprising a housing, a tank, and a protective cover, characterized in that the tank is located within the housing, the fuel compartments for storing the spent fuel are placed in the tank, the tank is provided with a heat-conducting structure to conduct heat away from the fuel compartments, and the protective cover is located at two ends of the housing to seal it. Preferably, the tank includes a plurality of modules located parallel to each other at intervals and connected via a connecting rod; the modules include a circular support ring and an annular side wall arranged 1745369 of 27 around a support plate, the heat-conducting structure is located within the modules. The heat-conducting structure is a grid structure formed by a plurality of heat-transfer plates, where the grid structure is formed by inserting and splicing horizontally arranged heat-transfer plates and vertically arranged heat-transfer plates together. The fuel compartments are located in parallel, and each fuel compartment is inserted through a respective cell into the grid structure. Preferably, the horizontally arranged heat transfer plates and the vertically arranged heat transfer plates are both provided with grooves so that the horizontally arranged heat transfer plates and the vertically arranged heat transfer plates can be inserted and joined together. Preferably, the modules also include a criticality control structure. Preferably, the criticality control structure is a neutron absorber that coats the heat transfer plates. Preferably, the side wall is formed by splicing together a plurality of aluminum blocks. Preferably, the tank comprises a plurality of support plates and a plurality of heat-conducting plates, the plates being arranged 1745369 of 27 support and the heat-conducting plates parallel at intervals and connected in series through the connecting rod. Preferably, the support plates have a plurality of first through-holes, and the heat-conducting plates have a corresponding plurality of second through-holes. The plurality of fuel compartments are arranged in parallel, each fuel compartment being inserted through a respective first and second through-hole. The fuel compartment consists of a neutron absorber, and the neutron absorber is lined with a layer of stainless steel. Preferably, the protective cover comprises an upper end protective cover and a lower end protective cover, and the upper end protective cover and the lower end protective cover cover the housing at two ends, respectively. Preferably, the upper end protective cover includes a first outer cover, a first inner cover, and a first protective plug stacked from the outside in, with the first protective plug in contact with the top of the tank, and the lower end protective cover includes a second outer cover, a second protective plug, and a second inner cover stacked from the outside in, with the second inner cover in contact with the 1745369 of 27 deposit fund. Preferably, the spent fuel storage and transport container also includes vent and siphon ports. The vent and siphon ports include a drain pipe, a vent hole, and a drain hole located in the casing. The drain pipe extends to the bottom of the casing, quick-connect fittings are mounted on the vent and drain ports respectively, and the drain port is connected to the drain pipe. Preferably, the spent fuel storage and transport container also includes a limiting block mounted inside the housing to prevent rotation of the tank with respect to the housing during transport. Preferably, a support ring is located inside an upper end of the housing, the support ring being connected to the housing to support the protective cover of the upper end, and a lug is located on an inner side of the support ring. Preferably, the spent fuel storage and transport container also includes a gripping ring located on an outer surface of the second outer cover for pushing and pulling the casing in a horizontal direction. 1745369 of 27 The spent fuel storage and transport container according to the present invention has good heat conduction performance and, when the module includes a criticality control structure, the criticality performance is also good, so that the heat generated during the storage of the spent fuel can be efficiently conducted outwards, the neutrons generated during the storage of the spent fuel can be absorbed, the structure is stable and the operation is easy during storage and transport. The used fuel storage and transport container also features a simple structure, convenient processing, lower costs, among other characteristics. Brief description of the figures Fig. 1 is a schematic view of a spent fuel storage and transport container according to the example of Embodiment 1 of the present invention; Fig. 2 is a schematic perspective view of a tank according to the example of Embodiment 1 of the present invention; Fig. 3 is a side view of the tank according to the example of Embodiment 1 of the present invention; 1745369 of 27 Fig. 4 is a schematic view illustrating a positional relationship between the fuel compartments, a neutron absorber, and a heat transfer plate according to the example of Embodiment 1 of the present invention; Fig. 5 is a top view of a single module of the tank according to the example of Embodiment 1 of the present invention; Fig. 6 is a schematic perspective view of a single module of the tank according to the example of Embodiment 1 of the present invention; Fig. 7 is a top view of a grid mechanism inside a tank module according to the example of Embodiment 1 of the present invention; Fig. 8 is a schematic perspective view of a grid mechanism inside a tank module according to the example of Embodiment 1 of the present invention; Fig. 9 is a schematic structural view of a spent fuel storage and transport container according to the example of Embodiment 3 of the present invention; Fig. 10 is a schematic structural view of a tank according to the example of Embodiment 3 of the present invention; Fig. 11 is a schematic structural view of a support ring 1745369 of 27 according to the example of Implementation 3 of the present invention; Fig. 12 is a schematic structural view of an external support-type gripping ring according to the example of Embodiment 3 of the present invention; Fig. 13 is a schematic structural diagram of an internal buckling type gripping ring according to the example of Embodiment 3 of the present invention. References: 1 - casing, 2 - connecting rod, 3 - support plate, 4 - side wall, 5 - heat transfer plate, 6 - neutron absorber, 7 - groove, 8 - first outer cover, 9 - first inner cover, 10 - first protective plug, 11 - second outer cover, 12 - second protective plug, 13 - second inner cover, 14 - vent holes and siphon, 15 - support ring, 16 - lug, 17 - grip ring, 18 - fuel compartment, 19 - support plate, 20 - heat conductive plate, 21 - nut, 22 - damper block, 23 - positioning block, 24 - upper plate component, and 25 - lower plate component. Detailed description of the achievements The technical solutions of the present invention will be clearly and completely described with reference to the accompanying figures. It should be understood that the described embodiments are not exhaustive but only some examples. 1745369 of 27 of the present invention. Any other embodiment, which a person skilled in the art can derive from the examples of embodiment provided herein without any creative effort, will be within the scope of the present invention. In the description of the present invention, it should be noted that the indication of orientation or positional relation, as above or similar, is based on the orientation or positional relation shown in the figures, and is only for convenience and simplicity of description, and does not indicate or imply that the device or element referred to must be located in a specific orientation or constructed and operated in a specific orientation and, therefore, should not be interpreted as a limitation of the present invention. In the description of the present invention, the terms first and second are used for descriptive purposes only and are not intended to indicate or imply relative importance. In describing the present invention, it should be noted that, unless explicitly specified or limited otherwise, the terms connected, located, mounted, fixed, and the like should be interpreted broadly, for example, a fixed connection, a detachable connection, an integral connection, a direct connection, an indirect connection through an intermediary, or a connection between two elements. The specific meanings of the foregoing terms in the present invention may be determined by those skilled in the art, in accordance with specific situations. 1745369 of 27 matter. The present invention provides a container for storing and transporting spent fuel, comprising a housing, a tank, and a protective cover. The tank is located within the housing, the fuel compartments for storing the spent fuel are located within the tank, the tank is provided with a heat-conducting structure to conduct heat away from the fuel compartments, and the protective cover is located at both ends of the housing to seal it. Example implementation 1 The present embodiment presents a container for storing and transporting spent fuel, comprising a housing 1, a tank, and a protective cover. The housing 1 is a cylindrical container with an internal cavity and openings at both ends. The tank is located inside the housing 1; fuel compartments 18 for storing spent fuel are located within the tank, and the tank is provided with a heat-conducting structure to conduct heat away from the fuel compartments 18. The protective cover is located at both ends of the housing 1 to seal it. As shown in Figs. 2 and 3, the deposit includes a plurality of 1745369 of 27 modules located parallel at intervals and connected via connecting rod(s) 2. The modules include a circular support ring 15 and an annular side wall 4 arranged around a support plate 3. The support ring 15 and the side wall 4 together form a tank frame structure. As shown in Figures 5 and 6, the heat-conducting structure is located within the modules. This structure is a grid formed by a plurality of heat transfer plates 5. The grid is created by splicing horizontally arranged and vertically arranged heat transfer plates 5 together, creating a plurality of cells for housing the fuel compartments 18 within each module. The fuel compartments 18 are arranged in parallel, each inserted through a respective cell in the grid structure. In each module, adequate space is reserved between the grid structure formed by a plurality of heat transfer plates 5 and the side wall 4 of the support plate 3 to provide space for thermal expansion and cold contraction of the heat transfer plates 5, so as to prevent the tank from being damaged due to too small a space between the heat transfer plates 5 and the side wall 4. 1745369 of 27 As shown in Figs. 7 and 8, the horizontally arranged heat transfer plates 5 and the vertically arranged heat transfer plates 5 are both provided with slots 7 for insertion and interlocking. Specifically, the slots 7 are located on the upper portions of the horizontally arranged heat transfer plates 5 and on the lower portions of the vertically arranged heat transfer plates 5. The slots 7 on the lower portions of the vertically arranged heat transfer plates 5 interlock with the slots 7 on the upper portions of the horizontally arranged heat transfer plates 5 to form a grid mechanism.Two adjacent heat transfer plates 5 arranged horizontally and two adjacent heat transfer plates 5 arranged vertically enclose a cell, and the cell has a size and dimension that matches the size and dimension of the fuel compartment 18. In this implementation example, the modules also include a criticality control structure. As shown in Fig. 4, the criticality control structure is a neutron absorber 6 that coats the heat transfer plates. The neutron absorber 6 is located on two lateral surfaces of the plate. 1745369 of 27 heat transfer 5 and forms a composite plate structure together with the heat transfer plate 5. The neutron absorber 6 of the composite plate directly contacts the fuel compartment 18 in the spent fuel storage process. The heat transfer plate 5 can effectively absorb the neutrons generated by the spent fuel and conduct out the heat generated by the spent fuel, thus protecting the safety of the entire storage container. In this embodiment, side wall 4 is formed by splicing together a plurality of aluminum blocks. As shown in Fig. 1, the protective cover includes a top end protective cover and a bottom end protective cover located at two ends of housing 1, respectively, to seal the two ends of housing 1. Specifically, the upper end protective cover includes a first outer cover 8, a first inner cover 9, and a first protective plug 10 stacked from the outside in, with the first protective plug 10 in contact with the top of the tank, and the lower end protective cover includes a second outer cover 11, a second protective plug 12, and a second inner cover 13 stacked from the outside in, with the second inner cover 13 1745369 of 27 in contact with the bottom of the deposit. In this embodiment, the spent fuel storage and transport container further includes vent and siphon holes 14. The vent and siphon holes include a drain pipe, a vent hole, and a drain hole located in housing 1. The drain pipe extends to the bottom of housing 1. Quick-connect fittings are mounted on the vent port and the drain port respectively, and the drain port is connected to the drain pipe to perform air filling and water drainage operations within housing 1. Optionally, the spent fuel storage and transport container also includes a limiting block. The limiting block is mounted inside housing 1 to prevent the tank from rotating relative to housing 1 during transport. As shown in Fig. 11, a support ring 15 is located inside one upper end of the housing 1. The support ring 15 is connected to the housing 1 to support the protective cover of the upper end. A lug is located on one inner side of the support ring 15 for lifting and mounting the spent fuel storage and transport container. 1745369 of 27 In this embodiment, the spent fuel storage and transport container further includes a gripping ring 17 located on an outer surface of the second outer cover 11 for pushing and pulling the housing 1 in a horizontal direction. Specifically, the gripping ring 17 can have two forms: one is the form shown in Fig. 12 for use in conjunction with an external support-type clamp, and the other is the form shown in Fig. 13 for use in conjunction with an internal buckling-type clamp, for pulling the spent fuel storage and transport container in the horizontal direction. The spent fuel storage and transport container in this embodiment has good heat conduction performance and good neutron absorption performance, which can be used effectively as a container for storing and transporting spent fuel, with the advantages of a simple structure, low cost and a firm structure, and can reduce the danger of a critical state of spent fuel. Implementation Example 2 The present embodiment describes a spent fuel storage and transport container that adopts a modular tank, which includes a tank located within a sealed housing 1 (the 1745369 of 27 casing 1 is made of 304 stainless steel sheet materials). One upper end of casing 1 is sealed with a protective top end cover, and one lower end of casing 1 is sealed with a protective bottom end cover. Fuel compartments 18 for storing spent fuel are located inside the tank, which is composed of a plurality of modules. Also located in the module are a criticality control structure and a heat conduction structure to conduct heat (the heat comes from the spent fuel loaded into the container) out of the fuel compartments 18. The tank is formed by stacking a plurality of modules connected in series via connecting rod(s) 2. Each module includes a circular support plate 3 and an annular side wall 4 surrounding a lateral surface of the support plate 3. The side wall 4 is formed by splicing together a plurality of aluminum blocks, and fuel compartments 18 are inserted through the support plate. 3. The heat-conducting structure is a grid structure of heat-transfer plates 5 located on the support plate 3, with a space reserved between each of the two ends of the heat-transfer plate 5 and the side wall 4. The criticality control structure is a neutron absorber 6 located on two sides of the heat-transfer plate 5. The fuel compartments 18 are inserted through a grid formed by the heat-transfer plate 5 and the 1745369 of 27 neutron absorber 6, so that critical control and heat export from fuel compartments 18 are achieved. In the processes of underwater operations of loading, unloading, drying, sealing, transfer and storage, the geometric structure of the tank and the neutron absorber 6 are intended to absorb neutrons to ensure the critical safety of the spent fuel assembly. As shown in Figs. 7 and 8, the heat transfer plate 5 and neutron absorber 6 are provided with slots 7, and the heat transfer plate 5 and neutron absorber 6 are inserted and spliced ​​into a grid structure through the slots 7. As shown in Fig. 4, a plurality of fuel compartments 18 are arranged in parallel and each fuel compartment 18 is inserted through each grid constructed by the heat transfer plate 5 and the neutron absorber 6. The upper and lower ends of the tank are positioned as open structures, and an axial load from fuel compartment 18, used to store spent fuel, is applied directly to the protective cover at the upper and lower ends of the container, rather than acting on the tank itself. The spent fuel is supported laterally by fuel compartment 18, while fuel compartment 18 is itself supported laterally by the plate. 1745369 of 27 support 3, the heat transfer plate 5 and the housing 1 (i.e., the container housing). The upper end protective cover includes a first outer cover 8 (made of 304 stainless steel sheet materials), a first inner cover 9 (made of 304 stainless steel sheet materials), and a first protective plug 10 (made of 304 stainless steel forgings) that are stacked sequentially, with a gap between the lower surface of the first protective plug 10 and the top of the tank. The lower end protective cover includes a second outer cover 11 (made of 304 stainless steel sheet materials), a second protective plug 12 (made of 304 stainless steel forgings), and a second inner cover 13 (made of 304 stainless steel sheet materials) that are stacked sequentially. The second inner cover 13 is in contact with the bottom of the tank. The vent and siphon ports 14 are located within the upper end of the housing 1 to perform air drainage and filling operations within the housing 1 while providing a protective effect. The vent and siphon ports 14 include a vent port and a drain port intended for air drainage and filling operations. Normally closed quick-connect fittings are located in the vent port and the drain port; the lower end of the drain port is connected to a drain pipe that is 1745369 of 27 extends to the bottom of housing 1. A limiting block is welded to an inner side of housing 1 to prevent the tank from rotating with respect to housing 1 during a horizontal transfer or transport process. A support ring 15 is welded inside the upper end of housing 1, and the support ring 15 is connected to housing 1 to support the upper end protective cover. A plurality of lugs 16 are located on housing 1 and support ring 15 (some of the lugs 16 are welded to housing 1 and some are welded to support ring 15) for lifting and mounting the container. A gripping ring 17 is welded to an outer surface of the second outer cover 11 of the lower end protective cover for pushing and pulling housing 1 horizontally, and the structure of the gripping ring 17 can accommodate an external support-type clamp. The spent fuel storage and transport container in this embodiment has the advantages of low cost, simple manufacturing process, robust structure, maintenance-free operation, and good heat conduction. The arrangement of the heat transfer plates and neutron absorber effectively dissipates heat from the spent fuel within the container, reducing the risk of the spent fuel assembly reaching a critical state. 1745369 of 27 Example of implementation 3 As shown in Fig. 9, the present embodiment features a spent fuel storage and transport container, comprising a housing 1, a tank, and a protective cover. The tank is located within the housing 1, which is a cylindrical container with two open ends. Fuel compartments 18 for storing spent fuel are located within the tank, which is provided with a heat-conducting structure to conduct heat away from the fuel compartments 18. The protective cover is located at two ends of the housing 1 to seal it. As shown in Fig. 10, the tank includes a plurality of support plates 19 and a plurality of heat-conducting plates 20. The plurality of support plates 19 and the plurality of heat-conducting plates 20 are arranged parallel to each other at intervals and are connected in series by the connecting rod(s) 2. The upper part of the connecting rod 2 is fixed to a nut 21 by an upper assembly, and the lower part of the connecting rod 2 is fixed to a damping block 22 by a lower assembly. In this embodiment, the support plate 19 and the heat-conducting plate 20 are separated by a positioning block 23. 1745369 of 27 positioning block 23 has a circular ring structure. A circular hole in the center of the positioning block 23 is sleeved in the connecting rod 2. Specifically, the heat-conducting plate 20 in this embodiment only needs to be located in a position corresponding to a middle section of the housing 1. This is because such an arrangement can already satisfy the amount of heat conduction during the storage of spent fuel. Of course, the heat-conducting plate 20 can also be arranged so that it is distributed along the entire length of the housing 1 or it can be arranged only in two side sections of the housing 1 (the housing includes a central section and two side sections apart from the central section). In this embodiment, a plurality of first through-holes are opened in the support plate 19, and a plurality of second through-holes are correspondingly opened in the heat-conducting plate 20. The plurality of fuel compartments 18 are arranged in parallel, each fuel compartment 18 being inserted through a respective first through-hole and a second through-hole. The fuel compartment 18 comprises a neutron absorber, and the neutron absorber is lined with a layer of stainless steel. During the spent fuel storage process, the generated neutrons are absorbed by the neutron absorber, and the heat is dissipated. 1745369 of 27 generated is conducted out of housing 1 through the stainless steel layer. In this embodiment, the support plate 19 and the heat-conducting plate 20 are stacked at intervals so that the heat generated during spent fuel storage is efficiently conducted. The fuel compartments 18 are made of a neutron-absorbing material so that the neutrons generated by the spent fuel can be effectively absorbed, thus improving safety. The other structures in this implementation example are the same as those in Implementation 1, so their description is omitted. Example of implementation 4 The present embodiment describes a spent fuel storage and transport container incorporating an integral tank, which includes a tank located within a sealed housing 1 (made of 304 stainless steel sheet material). An upper end of the housing 1 is sealed with a protective top cover, and a lower end of the housing 1 is sealed with a protective bottom cover. Fuel compartments 18 are for storing 1745369 of 27 spent fuel are placed inside the tank and the tank is provided with a heat-conducting structure to conduct heat away from the fuel compartments 18. The tank consists of stacked support plates 19 and heat-conducting plates 20. The support plates 19 and the heat-conducting plates 20 are positioned parallel to each other at intervals and are connected in series by the connecting rod(s) 2. The upper part of the connecting rod 2 is fixed to a nut 21 by means of a component of the upper plate 24, and the lower part of the connecting rod 2 is fixed to a damping block 22 by means of a component of the lower plate 25. The support plates 19 and the heat conductive plates 20 are separated by a positioning block 23. The fuel compartments 18 are arranged in parallel, and the fuel compartments 18 are inserted through the support plates 19 and the heat-conducting plates 20; the fuel compartments 18 are in contact with the heat-conducting plates 20, and the heat-conducting plates 20 are in contact with the housing 1. The body of fuel compartment 18 is composed of a neutron absorber. One outer surface of the absorber is coated with a layer of stainless steel. In underwater operations 1745369 of 27 of loading, unloading, drying, sealing, transfer and storage, the geometric structure of the tank and the neutron absorber are intended to absorb neutrons to ensure the critical safety of the spent fuel assembly. The upper and lower ends of the tank are both in open structures. An axial load from the fuel compartment 18, used to store spent fuel, is applied directly to the protective cover at the upper end and the protective cover at the lower end of the container, rather than acting on the tank itself. The spent fuel is supported laterally by the fuel compartment 18, while the fuel compartment 18 is itself supported laterally by the support plate 19, the heat-conducting plate 20, and the casing 1 (i.e., the container shell). The upper-end protective cover includes a first outer cover 8 (made of 304 stainless steel sheet materials), a first inner cover 9 (made of 304 stainless steel sheet materials), and a first protective plug 10 (made of 304 stainless steel forgings) that are stacked sequentially, with the first protective plug 10 in contact with the top of the tank. The lower-end protective cover includes a second outer cover 11 (made of 304 stainless steel sheet materials), a second protective plug 12 (made of 304 stainless steel forgings), and a second inner cover 13 (made of 1745369 of 27 stainless steel sheet materials (304) that are stacked sequentially. The second inner cover 13 is in contact with the bottom of the tank. The vent and siphon ports 14 are located within the upper end of the housing 1 to perform air drainage and filling operations within the housing 1 while providing a protective effect. The vent and siphon ports 14 include a vent port and a drain port intended for air drainage and filling operations. Normally closed quick-connect fittings are located in the vent port and the drain port; the lower end of the drain port is connected to a drain pipe that extends to the bottom of the housing 1. A limiting block is welded to an inner side of housing 1 to prevent the tank from rotating with respect to housing 1 during a horizontal transfer or transport process. A support ring 15 is located inside the upper end of housing 1, and the support ring 15 is connected to housing 1 to support the upper end protective cover. A lug 16 is located above the support ring 15 for lifting the container. A gripping ring 17 is welded to an outer surface of the second outer cover 11 of the lower end protective cover for pushing and pulling housing 1 in a horizontal direction, and the structure of the gripping ring 17 can be adapted to an external support-type clamp or an internal buckling-type clamp. 1745369 of 27 The spent fuel storage and transport container in this embodiment offers the advantages of low cost, simple manufacturing process, robust structure, maintenance-free operation, and good heat conduction. The arrangement of the heat transfer plates and neutron absorber plates effectively dissipates heat from the spent fuel within the container, reducing the risk of the spent fuel assembly reaching a critical state. It should be understood that the preceding embodiments are merely examples to illustrate the principle of this invention. However, the present invention is not limited to them. A person skilled in the art may make various modifications and variations without departing from the scope of the present invention. These modifications and variations should be considered within the scope of protection of the present invention.

Claims

1. A container for storing and transporting spent fuel, comprising a housing (1), a tank, and a protective cover, characterized in that the tank is located within the housing (1), the fuel compartments (18) for storing the spent fuel are located within the tank, the tank is provided with a heat-conducting structure for conducting heat away from the fuel compartments (18), and the protective cover is located at two ends of the housing (1) to seal said housing (1); wherein the tank comprises a plurality of modules arranged parallel to each other and connected by a connecting rod (2) substantially without gaps, each module comprising a circular support ring (15) and an annular side wall (4) arranged around a support plate (3) and formed by joining a plurality of aluminum blocks, the heat-conducting structure being located within the modules,the heat-conducting structure being a grid structure formed by a plurality of heat-transfer plates (5) extending in a plane perpendicular to the support plate (3), wherein the grid structure is formed by inserting and splicing together the horizontally arranged heat-transfer plates (5) and the vertically arranged heat-transfer plates (5), the plurality of fuel compartments (18) being arranged in parallel, and the plurality of fuel compartments (18) being each inserted through a respective cell of the grid structure; wherein the heat-transfer plate (5) of the heat-conducting structure provided in one of the plurality of modules is supported, substantially without gaps, against the heat-transfer plate (5) of the heat-conducting structure provided in another of the plurality of modules that is adjacent to the one of the plurality of modules,so that a heat transfer path is formed that is continuous within the plane perpendicular to the support plate (3), wherein the grid structure formed by the plurality of heat transfer plates (5) is detachably provided with gaps in the side wall (4) of the support plate (3); wherein the horizontally arranged heat transfer plates (5) and the vertically arranged heat transfer plates (5) are provided with slots (7) so that the horizontally arranged heat transfer plates (5) and the vertically arranged heat transfer plates (5) are inserted and spliced ​​together; wherein two layers of neutron absorber (6) are provided on both sides of each heat transfer plate (5),Each layer of the neutron absorber (6) is an individual flat-plate structure and is provided with corresponding slots (7) to form a corresponding grid structure by inserting and splicing the neutron absorber (6) to form a complete and closed neutron absorber structure. The corresponding grid structure is consistent with the grid structure formed by the heat transfer plates (5). Six claims follow.