A solid state core fuel assembly and shielding system

Abstract

The application discloses a solid core fuel assembly and shielding system, and belongs to the nuclear power field. The solid core fuel assembly comprises a base body with fuel rod mounting holes, fuel rods are arranged in the fuel rod mounting holes and a sealing section is formed between the fuel rods and the end of the fuel rod mounting hole, a deep hole end plug is arranged in the sealing section to seal the fuel rods in the fuel rod mounting hole, and end cover plates are fixed to the two ends of the base body. The solid core fuel assembly can form multilayer containment for the core radioactive substances, and in the case that the fuel rod cladding is damaged, the deep hole end plug can be used to seal the radioactive substances in the fuel rod mounting hole of the base body, so that the safety and reliability of the solid core are improved. The application further provides a solid core shielding system.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power, specifically relating to a solid reactor core fuel assembly and shielding system. Background Technology

[0002] Solid reactors, as a new type of reactor, do not employ the liquid primary loop of pressurized water reactors. Instead, they dissipate the heat generated by the fuel rods through a solid medium. Because the high-pressure primary loop is omitted, solid reactors have advantages such as simple structure, small size, and inherently good safety. However, solid reactors also lack the safety barrier of the pressurized water reactor's coolant system pressure boundary, thus increasing the risk of leakage should a fuel rod rupture occur.

[0003] Therefore, providing a solid reactor core fuel assembly with higher safety is of positive significance for further improving the safety and reliability performance of solid reactor cores. Summary of the Invention

[0004] The purpose of this invention is to provide a solid reactor core fuel assembly that improves the safety and reliability of solid reactor cores. This invention also provides a solid reactor core shielding system.

[0005] According to one embodiment of the present invention, a solid reactor core fuel assembly is provided, the fuel assembly comprising fuel rods and a substrate, the substrate being provided with fuel rod mounting holes, the fuel rods being disposed within the fuel rod mounting holes of the substrate. The fuel assembly further includes deep-hole end plugs and end caps; wherein,

[0006] A sealing section is provided between each end of the fuel rod and the end of the fuel rod mounting hole;

[0007] The deep hole end plug is installed and fixed in the sealing section to seal the fuel rod in the fuel rod mounting hole;

[0008] The end caps are fixed to both ends of the base.

[0009] By installing deep-hole end plugs, the fuel rods can be sealed within the substrate, preventing radioactive materials from leaking out of the solid reactor core substrate when the fuel rod cladding breaks, thereby improving the safety of the solid reactor core.

[0010] Furthermore, in some embodiments, a groove is provided on the outer periphery of the deep hole end plug, and a sealing ring is provided in the groove.

[0011] Sealing rings can improve the sealing performance of deep hole end plugs. The sealing rings can be made of high-temperature resistant alloy materials or composite materials.

[0012] Furthermore, in some embodiments, a sealant is provided on the outer periphery of the deep hole end plug.

[0013] The sealant can further improve the sealing performance of the deep hole end plug, making the installation of the deep hole end plug more secure.

[0014] Furthermore, in some embodiments, the end cap is provided with an installation tube that matches the fuel rod mounting hole, the installation tube is inserted into the sealing section, and the deep hole end plug is installed and fixed in the installation tube.

[0015] Furthermore, in some embodiments, the deep hole end plug is fixed by welding.

[0016] Furthermore, in some embodiments, the inner wall surface of the sealing section of the fuel rod mounting hole and the outer peripheral side of the deep hole end plug are provided with matching threads, and the deep hole end plug is fixed to the sealing section by threaded connection.

[0017] Furthermore, in some embodiments, a gap is reserved between the deep-hole end plug and the end face of the fuel rod.

[0018] Furthermore, in some embodiments, the gap between the high-burnup fuel rod and the deep-hole end plug is greater than the gap between the low-burnup fuel rod and the deep-hole end plug.

[0019] Furthermore, in some embodiments, the deep hole end plug is manufactured using one or more combinations of nickel-based alloys, stainless steel, zirconium alloys, and SiC composite materials.

[0020] According to another aspect of the present invention, a solid-state reactor core shielding system is provided, the system comprising a fuel assembly and a solid-state reactor core containment, wherein the fuel assembly is a solid-state reactor core fuel assembly provided in any of the foregoing embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the solid core fuel assembly structure in one embodiment;

[0022] Figure 2 This is an exploded view of a solid reactor core fuel assembly in one embodiment;

[0023] Figure 3 This is a schematic diagram of a deep-hole end plug structure in one embodiment;

[0024] Figure 4 This is a schematic diagram of a deep-hole end plug structure in another embodiment;

[0025] Figure 5 for Figure 4 Schematic diagram of the assembly of the end plug for medium-deep holes;

[0026] Figure 6 This is a schematic diagram of the assembly of the deep hole end plug and end cap in another embodiment.

[0027] Meaning of the reference numerals in the attached figures:

[0028] 1-End cover plate; 2-Deep hole end plug; 3-Base; 4-Fuel rod mounting hole; 5-Thread; 6-Sealing ring; 7-Mounting tube; 8-Slot.

[0029] The purpose of the above-described drawings is to provide a detailed description of the present invention so that those skilled in the art can understand the technical concept of the invention, and is not intended to limit the invention. For the sake of brevity, the above-described drawings only schematically depict the structures related to the technical features of the present invention, and do not depict the complete structure and all details strictly according to actual scale. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0031] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment herein. The phrase appearing in various places 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 will understand that the embodiments herein can be combined with other embodiments without causing structural conflicts.

[0032] In this description, unless otherwise explicitly specified and limited, the technical terms "installation," "connection," "joining," etc., should be interpreted broadly, for example, referring to movable connections, fixed connections, or integration. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0033] In this description, terms such as "upper," "lower," "left," "right," "lateral," "longitudinal," "height," "length," and "width," which indicate orientation or positional relationships, are intended to accurately describe the embodiments and simplify the description, rather than limiting the parts or structures involved to have a specific orientation, or to be installed or operated in a specific orientation, and should not be construed as limiting the embodiments in this document.

[0034] In this description, terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating relative importance or limiting the number, specific order, or primary / secondary relationship of the described technical features. In this description, "multiple" means at least two.

[0035] A solid-fuel reactor is a type of nuclear reactor that uses the fuel assembly itself as a heat transfer medium, combined with the characteristics of heat transfer equipment, to remove the heat released from the nuclear fuel. This solid-fuel reactor structure differs significantly from traditional pressurized water reactors or gas-cooled reactors. It eliminates the complex flow channels for the flowing cooling medium, requires no coolant loop or main pump, and has no risk of loss of flow. It possesses inherent technical characteristics such as safety, quiet operation, reliability, and simplification.

[0036] Because the flowing cooling medium and complex primary loop are omitted, all-solid reactor cores lack the pressure boundary safety barrier of pressurized water reactor coolant systems, increasing the probability and risk of radioactive material leakage into the environment and failing to meet the safety barrier design requirements of nuclear power regulations. Therefore, embodiments of the present invention provide a multi-layered safety barrier solid reactor core fuel assembly design to meet nuclear power regulations, reduce the risk of radioactive material leakage, and improve the safety of solid reactor cores.

[0037] One embodiment of the present invention provides a solid reactor core fuel assembly. The structure of the fuel assembly is as follows: Figure 1 and Figure 2 As shown, the reactor includes fuel rods (not shown) and a substrate 3. The substrate 3 has multiple fuel rod mounting holes 4 through which the fuel rods pass. Heat pipes are spaced apart within the array of fuel rods to dissipate the heat generated in the fuel rods. Multiple such fuel assemblies are stacked together to form a solid-state heat transfer structure for the solid reactor core, which is then enclosed by a containment vessel located on the outer side.

[0038] The axial length of the fuel rod is shorter than the axial length of the fuel rod mounting hole 4. When the fuel rod is inserted into the fuel rod mounting hole 4, a distance is reserved between both ends of the fuel rod and the end of the fuel rod mounting hole 4 as a sealing section. Deep hole end plugs 2 are installed and fixed in the sealing sections at both ends of the fuel rod mounting hole 4. The deep hole end plugs 2 seal the fuel rod inside the fuel rod mounting hole 4, forming a closed structure outside the fuel rod cladding. In this way, when the fuel rod cladding ruptures due to irradiation or melts down, the deep hole end plugs 2 can continue to seal the radioactive material released from the fuel rod cladding within the fuel rod mounting hole, thereby improving the safety of the solid reactor core.

[0039] At both ends of the substrate 3, end caps 1 are fixed, and the end caps 1 serve as a fixing structure to fix the fuel assembly inside the solid reactor core.

[0040] In some embodiments, the end cap 1 itself has a sealing function and can seal the fuel rod mounting hole 4.

[0041] In some embodiments, such as Figure 3As shown, the outer circumference of the deep hole end plug 2 is provided with a thread 5, and the sealing section of the fuel rod mounting hole 4 is correspondingly provided with a thread structure that matches the thread 5, so that the deep hole end plug 2 can be fixedly installed in the sealing section of the fuel rod mounting hole 4 by the thread 5.

[0042] In a further preferred embodiment, the thread 5 may be provided with sealant to make the deep hole end plug 2 more securely installed in the sealing section of the fuel rod mounting hole 4.

[0043] In a preferred embodiment, the deep hole end plug 2 is provided with a groove 8 on the side facing the outside of the base 3 so that the deep hole end plug can be screwed into the sealing section of the fuel rod mounting hole 4 using an assembly tool.

[0044] In a preferred embodiment, such as Figure 4 As shown, a groove is provided on the outer circumference of the deep hole end plug 2, and a sealing ring 6 is placed in the groove. During installation, as... Figure 5 As shown, the sealing ring 6 can be squeezed and deformed to seal the circumferential gap between the deep hole end plug 2 and the fuel rod mounting hole 4.

[0045] The deep-hole end plug 2, equipped with a sealing ring 6, can be snapped into the fuel rod mounting hole 4, or it can be fixedly connected to the inner wall of the fuel rod mounting hole 4 by welding. Alternatively, a support structure, such as a support rod or support tube, can be provided on the end cover plate 1 extending into the fuel rod mounting hole 4 to press the deep-hole end plug 2 tightly along the axial direction.

[0046] In other embodiments, such as Figure 6 As shown, the end cover plate 1 is provided with an installation tube 7, the position of which corresponds to each fuel rod mounting hole 4. When the end cover plate 1 is installed at both ends of the base 3, the installation tube 7 is inserted into the sealing section of the fuel rod mounting hole 4, and the outer wall of the installation tube 7 is press-fitted with the inner wall of the fuel rod mounting hole 4 to form a seal. The deep hole end plug 2 is installed and fixed in the installation tube 7 to achieve the seal of the fuel rod mounting hole 4.

[0047] In a further preferred embodiment, the deep-hole end plug 2 can be welded and fixed to the inner wall of the mounting tube 7. The deep-hole end plug 2 can be pre-welded and fixed to the mounting tube 7 before the fuel assembly is assembled, so as to save assembly time on site; or it can be welded and installed one by one during the overall assembly of the fuel assembly.

[0048] In a preferred embodiment, a gap is reserved between the deep hole end plug 2 and the end of the fuel rod to accommodate the fission gas generated by the combustion of the fuel rod and to accommodate the axial thermal deformation and irradiation growth of the entire fuel rod.

[0049] In a further preferred embodiment, based on the distribution of fuel rods throughout the solid core, fuel rods at different locations have different burn-out depths. For high burn-out fuel rods, the gap between their ends and the deep hole end plug 2 is larger than the gap between low burn-out fuel rods and the deep hole end plug 2, in order to avoid excessive fission gas pressure generated by high burn-out fuel rods in the later stages.

[0050] In a preferred embodiment, the deep hole end plug 2 can be made of heat-resistant alloy materials such as nickel-based alloys, zirconium alloys, and stainless steel, or it can be made of composite materials such as SiC composite materials that have good resistance to neutron irradiation, or it can be made of a combination of the above materials. For example, the main body of the deep hole end plug 2 is made of SiC composite material, and the outer periphery is provided with an outer wall made of metal material to facilitate welding and fixing.

[0051] The solid reactor core using the solid fuel assembly provided in the above embodiments has a three-layer composite shielding system from the inside out. Specifically, the fuel rod cladding encloses the fuel pellets, serving as the first layer of safety shielding; the deep-hole end plugs 2 enclose the fuel rods within the fuel rod mounting holes 4 of the substrate 3, preventing radioactive material leakage in the event of fuel rod cladding damage, forming the second layer of safety shielding; and the solid core containment shell encloses all the fuel assemblies, isolating them from the external environment, forming the third layer of safety shielding.

[0052] This solid-state reactor core safety shielding system can form multiple layers of shielding for the active regions within the solid-state reactor core, effectively maintaining the long-term containment of radioactive materials in the core under accident conditions, thereby improving the safety and reliability of the solid-state reactor core.

[0053] The purpose of the above embodiments is to provide a further detailed description of the present invention in conjunction with the accompanying drawings, so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, optimization or equivalent replacement of the involved part structures, as well as combination of implementation methods in different embodiments without causing structural and principle conflicts, all fall within the protection scope of the present invention.

Claims

1. A solid reactor core fuel assembly, comprising fuel rods and a substrate, wherein the substrate is provided with fuel rod mounting holes, and the fuel rods pass through the fuel rod mounting holes in the substrate, characterized in that, It also includes deep-hole end plugs and end caps; among which, A sealing section is provided between each end of the fuel rod and the end of the fuel rod mounting hole; The deep hole end plug is installed and fixed in the sealing section to seal the fuel rod in the fuel rod mounting hole; The end caps are fixed to both ends of the base.

2. The solid reactor core fuel assembly according to claim 1, characterized in that, A groove is provided on the outer periphery of the deep hole end plug, and a sealing ring is provided in the groove.

3. The solid reactor core fuel assembly according to claim 1, characterized in that, The outer periphery of the deep hole end plug is provided with sealant.

4. The solid reactor core fuel assembly according to claim 1, characterized in that, The end cap plate is provided with an installation tube that matches the fuel rod mounting hole. The installation tube is inserted into the sealing section, and the deep hole end plug is installed and fixed inside the installation tube.

5. The solid core fuel assembly according to any one of claims 1 to 4, characterized in that, The deep hole end plug is fixed by welding.

6. The solid reactor core fuel assembly according to any one of claims 1 to 3, characterized in that, The inner wall of the sealing section of the fuel rod mounting hole and the outer peripheral side of the deep hole end plug are provided with matching threads, and the deep hole end plug is fixed to the sealing section by threaded connection.

7. The solid core fuel assembly according to any one of claims 1 to 4, characterized in that, A gap is reserved between the deep hole end plug and the end face of the fuel rod.

8. The solid reactor core fuel assembly according to claim 7, characterized in that, The gap between the high-burnup fuel rod and the deep-hole end plug is greater than the gap between the low-burnup fuel rod and the deep-hole end plug.

9. The solid reactor core fuel assembly according to any one of claims 1 to 4, characterized in that, The deep hole end plug is manufactured using one or more of the following materials: nickel-based alloy, stainless steel, zirconium alloy, and SiC composite material.

10. A solid-state reactor core shielding system, characterized in that, include Fuel assemblies and solid core containment, among which, The fuel assembly is a solid core fuel assembly as described in any one of claims 1 to 9.

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