Fuel short rod in-pile high-temperature irradiation test device and manufacturing method thereof

Abstract

The invention provides a fuel stub in-pile high-temperature irradiation test device and a manufacturing method thereof, and belongs to the technical field of high-temperature irradiation tests.The fuel stub in-pile high-temperature irradiation test device provided by the embodiment of the invention comprises a protection pipe, a test piece assembly and a first thermal resistance layer, and the first thermal resistance layer is additionally arranged outside a fuel stub; the first thermal resistance layer is arranged to increase the temperature gradient between the fuel stub and the inner cavity coolant, so that the high temperature of the stub cladding can be smoothly transited to the inner cavity coolant through the first thermal resistance layer, the fuel stub high-temperature irradiation test can be carried out in the low-temperature coolant, and the temperature upper limit of the irradiation test in the fuel stub pile can be improved.

Description

Technical Field

[0001] This application belongs to the field of high-temperature irradiation testing technology, specifically relating to a high-temperature irradiation testing device for fuel short rod reactors and its manufacturing method. Background Technology

[0002] To achieve higher thermal efficiency, a more compact layout, smaller size, and easier assembly / disassembly, the "new mass reactor" places higher demands on the processing performance of nuclear fuel, resulting in significant differences from existing fuels in key materials, design technologies, manufacturing, and testing processes. A major challenge in the development of new mass reactor fuel is conducting high-temperature irradiation tests within the research reactor. Existing high-temperature irradiation test facilities have relatively small temperature differences between the fuel core and coolant during high-temperature irradiation tests. To prevent leakage of high-temperature fission products, the upper limit of the test temperature cannot be too high, thus limiting irradiation testing. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] Therefore, a first aspect of the present invention provides a high-temperature irradiation test apparatus for fuel short rod reactors.

[0005] A second aspect of the present invention provides a method for manufacturing a high-temperature irradiation test apparatus for fuel short rod reactors.

[0006] In view of this, a high-temperature irradiation test apparatus for fuel short rod reactors is provided according to a first aspect of the embodiments of this application, comprising:

[0007] Protective tube, which includes an insulating casing;

[0008] The test component assembly is arranged within the receiving cavity enclosed by the heat insulation shell. The test component assembly includes several fuel rods, which are arranged parallel to the axis of the heat insulation shell.

[0009] The first thermal resistance layer is disposed along the circumference of the fuel rod and is located between the fuel rod and the thermal insulation shell.

[0010] In one feasible implementation, the first thermal resistance layer includes:

[0011] A heat insulation layer is disposed on the outside of the fuel short rod along the circumference of the fuel short rod. The heat insulation layer is sealed to the fuel short rod, and there is a first gap between the inner wall of the heat insulation layer and the outer wall of the fuel short rod.

[0012] A first filling layer is disposed within a first gap, and the first filling layer is bonded to the heat insulation layer and the fuel short rod;

[0013] The outer shell is arranged circumferentially on the outside of the insulation layer along the fuel rod. The outer shell is sealed to the insulation layer. There is a second gap between the inner wall of the outer shell and the outer wall of the insulation layer.

[0014] The second filling layer is disposed within the second gap and is bonded to the outer shell and the insulation layer.

[0015] In one feasible implementation, the high-temperature irradiation test apparatus for fuel short rod reactors further includes:

[0016] The first mounting slot is evenly arranged on the inner wall of the insulation layer along the circumference of the insulation layer. The first mounting slot is used to install the temperature monitoring device.

[0017] The second mounting slot is evenly arranged on the outer side wall of the insulation layer along the circumference of the insulation layer. The second mounting slot is used to install the temperature monitoring device. The second mounting slot is staggered from the first mounting slot.

[0018] In one feasible implementation, the protective tube further includes an upper connector and a lower connector, the upper connector being disposed at the first end of the heat insulation shell and the lower connector being disposed at the second end of the heat insulation shell.

[0019] The cavity contains at least two test component assemblies, which are arranged along the axial direction of the protective tube. The thickness of the first filling layer of the fuel short rod in the upper test component assembly is greater than that in the middle test component assembly. The thickness of the first filling layer of the fuel short rod in the upper test component assembly is greater than that in the lower test component assembly.

[0020] In one feasible implementation, several test specimen assemblies are arranged at equal intervals along the axial direction of the protective tube within the receiving cavity;

[0021] The fuel rods are evenly arranged in the containment cavity along the circumference of the protection tube.

[0022] In one feasible implementation, the thermal insulation shell includes a shell body;

[0023] The second thermal resistance layer is disposed on the outer side of the casing body along the circumference of the casing body.

[0024] In one feasible implementation, the second thermal resistance layer includes:

[0025] The outer sleeve is arranged circumferentially on the outside of the shell body. The outer sleeve is sealed to the shell body, and there is a third gap between the inner wall of the outer sleeve and the outer wall of the shell body.

[0026] The third filling layer is located within the third gap and is attached to the outer tube and the shell body.

[0027] In one feasible implementation, the high-temperature irradiation test apparatus for fuel short rod reactors further includes:

[0028] An open ring plug, which includes a filling port, is disposed circumferentially at the first end of the outer tube along the outer shell body, and a closed ring plug is sealed to the outer shell body and the outer tube.

[0029] A sealing ring plug is disposed at the second end of the outer sleeve along the circumference of the casing body, and the sealing ring plug is sealed to the casing body and the outer sleeve.

[0030] According to a second aspect of the embodiments of this application, a method for manufacturing a high-temperature irradiation test device for a fuel short rod reactor is provided, for manufacturing a high-temperature irradiation test device for a fuel short rod reactor as described in any of the above technical solutions, the method comprising:

[0031] Based on fuel phase volume and U 235 Enrichment is used to design the core loading and control the neutron flux level and line power density of the fuel rods;

[0032] Based on the core loading design values, calculate the accurate fuel heat release rate and line power, design the size of the fuel stubs, and design the size of the first thermal resistance layer;

[0033] An experiment was conducted using an electric heating tube with the same line power density instead of a fuel rod to measure the temperature gradient inside and outside the first thermal resistance layer under the designed line power.

[0034] Remove the electric heating tube, install fuel rods, and seal the irradiation device.

[0035] In one feasible implementation, the inner and outer diameters of the insulation layer are designed according to the axial position of the fuel rod in the inner coolant cavity.

[0036] The high-temperature irradiation test device and its manufacturing method for fuel short rod reactors disclosed in this application have the following advantages compared with the prior art:

[0037] The high-temperature irradiation test apparatus for fuel short rods provided in this application includes a protective tube, a test piece assembly, and a first thermal resistance layer. By adding a first thermal resistance layer outside the fuel short rod, the temperature gradient between the fuel short rod and the inner cavity coolant is increased, allowing the high temperature of the short rod cladding to smoothly transition to the inner cavity coolant through the first thermal resistance layer. This enables high-temperature irradiation tests of fuel short rods to be carried out in a low-temperature coolant, which is beneficial for increasing the upper limit of the irradiation test temperature for fuel short rods in the reactor. Attached Figure Description

[0038] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0039] Figure 1 A schematic structural diagram of the first angle of a high-temperature irradiation test apparatus for a fuel short rod reactor according to an embodiment of this application;

[0040] Figure 2 A schematic structural diagram of the first thermal resistance layer of a high-temperature irradiation test apparatus for a fuel short rod reactor according to an embodiment of this application;

[0041] Figure 3 A schematic structural diagram of the fuel rods in a high-temperature irradiation test apparatus for fuel rods in a reactor according to an embodiment of this application;

[0042] Figure 4 A schematic structural diagram of the three-grip positioning structure of a high-temperature irradiation test device for fuel short rods in a reactor, provided in this application;

[0043] Figure 5 A schematic structural diagram of the first and second mounting slots of a high-temperature irradiation test apparatus for a fuel short rod reactor according to an embodiment of this application;

[0044] Figure 6 A schematic diagram showing the location of temperature monitoring points on the fuel rods in a high-temperature irradiation test apparatus for fuel rods in a fuel rod pile, according to an embodiment of this application.

[0045] Figure 7 A schematic structural diagram of a high-temperature irradiation test apparatus for a fuel short rod reactor according to an embodiment of this application, taken from a second angle.

[0046] Figure 8 A schematic structural diagram of the second thermal resistance layer of a high-temperature irradiation test apparatus in a fuel short rod reactor according to an embodiment of this application;

[0047] Figure 9 A schematic flowchart illustrating the steps of a method for fabricating a high-temperature irradiation test apparatus for a fuel short rod reactor according to an embodiment of this application;

[0048] Figure 10 A design structural diagram of a high-temperature irradiation test apparatus for a fuel short rod reactor, provided in this application;

[0049] in, Figures 1 to 10 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0050] 1. Protective tube; 2. Test specimen assembly; 3. First thermal resistance layer; 4. Three-claw positioning structure; 5. First mounting groove; 6. Second mounting groove; 7. Second thermal resistance layer; 8. Open ring plug; 9. Closed ring plug;

[0051] 11. Thermal insulation casing; 12. Upper connector; 13. Lower connector; 14. Flow blocking component; 15. Throttling plug;

[0052] 111. Sheath body; 112. Upper sleeve; 113. Lower sleeve;

[0053] 20. Fuel rod; 21. Fuel core; 22. Rod sheath; 23. Elastic element; 24. Mounting base; 25. First sealing plug; 26. Second sealing plug; 27. Heat dissipation cavity;

[0054] 31. Insulation layer; 32. First filling layer; 33. Outer shell; 34. Second filling layer;

[0055] 71. Outer tube; 72. Third filler layer. Detailed Implementation

[0056] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0057] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0058] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0059] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0060] like Figure 1 and Figure 2 As shown, according to a first aspect of the embodiments of this application, a high-temperature irradiation test device for fuel short rods in a reactor is provided, comprising: a protective tube 1, a test component assembly 2, and a first thermal resistance layer 3; the protective tube 1 includes a heat-insulating shell 11; the test component assembly 2 is arranged in a receiving cavity enclosed by the heat-insulating shell 11, the test component assembly 2 includes a plurality of fuel short rods 20, the fuel short rods 20 being arranged parallel to the axis of the heat-insulating shell 11; the first thermal resistance layer 3 is arranged along the circumference of the fuel short rods 20, the first thermal resistance layer 3 being located between the fuel short rods 20 and the heat-insulating shell 11, the first thermal resistance layer 3 and the heat-insulating shell 11 enclosing an inner coolant cavity.

[0061] The fuel short rod in-reactor high-temperature irradiation test apparatus provided in this application includes a protective tube 1, a test piece assembly 2, and a first thermal resistance layer 3. By adding a first thermal resistance layer 3 outside the fuel short rod 20, the temperature gradient between the fuel short rod 20 and the inner cavity coolant is increased, so that the high temperature of the short rod cladding 22 can be smoothly transferred to the inner cavity coolant through the first thermal resistance layer 3, thereby realizing the high-temperature irradiation test of the fuel short rod 20 in the low-temperature coolant, which is beneficial to improving the upper limit of the in-reactor irradiation test temperature of the fuel short rod 20.

[0062] Furthermore, such as Figure 1 The protective tube 1 also includes an upper connector 12, a lower connector 13, a flow blocking element 14, and a throttling plug 15. The upper connector 12 is located at the first end of the heat insulation shell 11, and the lower connector 13 is located at the second end of the heat insulation shell 11. The flow blocking element 14 is located inside the inner coolant cavity and is used to simulate the blockage of the coolant flow channel under extreme conditions, and to study and evaluate the blockage that the fuel rod 20 may encounter in actual reactor operation. The throttling plug 15 is located inside the heat insulation shell 11 near the lower connector 13. The throttling plug 15 is provided with an adjustment port. By adjusting the size of the opening of the adjustment port of the throttling plug 15, the flow rate of coolant flowing through the fuel rod is controlled so as to maintain the operation of the fuel rod 20 at a specific power level.

[0063] Furthermore, such as Figure 3 The fuel rod 20 includes a fuel core 21, a short rod shell 22, an elastic element 23, a mounting base 24, a first sealing plug 25, and a second sealing plug 26. The fuel core 21 is provided with a heat dissipation cavity 27. The short rod shell 22 is wrapped around the outside of the fuel core 21. The first sealing plug 25 and the second sealing plug 26 seal the fuel core 21 inside the short rod shell 22 at both ends. The fuel core 21 is supported by the elastic element 23 to provide an expandable space for the fuel core 21.

[0064] like Figure 2 As shown, in one feasible embodiment, the first thermal resistance layer 3 includes: a heat insulation layer 31, a first filling layer 32, an outer shell 33, and a second filling layer 34; the heat insulation layer 31 is disposed on the outer side of the fuel rod 20 along the circumference of the fuel rod 20, and the heat insulation layer 31 is sealed to the fuel rod 20, with a first gap between the inner wall of the heat insulation layer 31 and the outer wall of the fuel rod 20; the first filling layer 32 is disposed within the first gap, and the first filling layer 32 is bonded to the heat insulation layer 31 and the fuel rod 20; the outer shell 33 is disposed on the outer side of the heat insulation layer 31 along the circumference of the fuel rod 20, and the outer shell 33 is sealed to the heat insulation layer 31, with a second gap between the inner wall of the outer shell 33 and the outer wall of the heat insulation layer 31; the second filling layer 34 is disposed within the second gap, and the second filling layer 34 is bonded to the outer shell 33 and the heat insulation layer 31.

[0065] In this technical solution, the first filling layer 32, the heat insulation layer 31, the second filling layer 34, and the outer shell 33 are sequentially arranged from the inside to the outside of the short rod shell 22. By setting the heat insulation layer 31, a large temperature gradient is established between the fuel short rod 20 and the inner cavity coolant. The outer shell 33 serves as the second boundary of the fuel short rod 20, further reducing the risk of leakage of radioactive materials inside the short rod shell 22 and improving the safety of the fuel short rod 20 during the test. The first filling layer 32 isolates the heat insulation layer 31 from the physical contact with the short rod shell 22, and the second filling layer 34 isolates the heat insulation layer 31 from the physical contact with the outer shell 33, reducing the uncertainty brought by the contact thermal resistance between the short rod shell 22, the heat insulation layer 31, and the outer shell 33 to the establishment of the test temperature field. At the same time, the first filling layer 32 and the second filling layer 34 also have a certain heat insulation effect, which is conducive to maintaining the temperature gradient between the fuel short rod 20 and the inner cavity coolant.

[0066] Furthermore, the heat insulation layer 31 is made of ceramic material for heat insulation, and the outer shell 33 is made of stainless steel to protect the internal structure. The first filling layer 32 between the heat insulation layer 31 and the short rod shell 22 is formed by filling with helium, and the second filling layer 34 between the heat insulation layer 31 and the outer shell 33 is formed by filling with helium. The first filling layer 32 and the second filling layer 34 further insulate and retain heat, avoiding the influence of contact thermal resistance on the accuracy of temperature field establishment. Specifically, when the wall thickness of the heat insulation layer 31 is 4 mm, a temperature difference of approximately 550°C can be established between the fuel short rod 20 and the internal coolant.

[0067] In some examples, such as Figure 4The first filling layer 32 is formed by using a three-claw positioning structure 4 to support and position the heat insulation layer 31 at both ends of the fuel short rod 20 to form a cavity, and then performing helium purging and sealing welding inside the heat insulation layer 31; the second filling layer 34 is formed by using a three-claw positioning structure 4 to support and position the outer shell 33 at both ends of the heat insulation layer 31 to form a cavity, and then performing helium purging and sealing welding inside the outer shell 33.

[0068] In some examples, the three-claw positioning structure 4 has three positioning surfaces: the inner wall of the claw head filling block contacts the short rod shell 22, the outer wall of the claw head filling block contacts and supports the inner wall of the heat insulation layer 31, forming a stable and reliable first gap on the side of the heat insulation layer 31 close to the short rod shell 22; the outer wall of the claw head positioning rib contacts and supports the inner wall of the outer shell 33, forming a stable and reliable second gap on the side of the heat insulation layer 31 away from the short rod shell 22.

[0069] As a preferred option, the thickness of the first gap and the second gap are set according to the heat release rate. For example, the gap needs to be larger in the upper test piece to reduce the heat dissipation of the fuel rod 20, while the gap needs to be smaller in the middle and lower test pieces to increase the heat dissipation of the fuel rod 20. As a preferred option, the first gap is ≤0.2mm. The temperature gradient outside the first thermal resistance layer 3 is small, and changing the thickness of the second filling layer 34 has little impact on the temperature. As a preferred option, the second gap is 0.015~0.025mm.

[0070] like Figure 5 As shown, in one feasible embodiment, the high-temperature irradiation test device for fuel short rod reactors further includes: a first mounting slot 5 and a second mounting slot 6; the first mounting slot 5 is evenly arranged along the circumference of the insulation layer 31 on the inner sidewall of the insulation layer 31, and the first mounting slot 5 is used to install a temperature monitoring device; the second mounting slot 6 is evenly arranged along the circumference of the insulation layer 31 on the outer sidewall of the insulation layer 31, and the second mounting slot 6 is used to install a temperature monitoring device, and the second mounting slot 6 is staggered from the first mounting slot 5.

[0071] In this technical solution, the first mounting groove 5 is arranged on the side wall of the insulation layer 31 near the fuel rod 20. A temperature monitoring device is installed in the first mounting groove 5 to detect the temperature of the inner side of the insulation layer 31. The second mounting groove 6 is arranged on the side wall of the fuel rod 20 near the outer shell 33. A temperature monitoring device is installed in the second mounting groove 6 to detect the temperature of the outer side of the insulation layer 31. The first mounting groove 5 and the second mounting groove 6 are staggered to monitor the temperature of the fuel rod 20 from different angles, so as to obtain more comprehensive thermal performance data, ensure that the fuel rod 20 is within a safe operating temperature range, prevent the fuel rod 20 from being damaged due to overheating, and conduct subsequent data analysis and research on the first thermal resistance layer 3 based on the monitored data to verify and improve the thermodynamic model of the fuel rod, optimize the design of the fuel rod 20, and improve the performance and reliability of the fuel rod 20 in practical applications.

[0072] In some examples, the first mounting groove 5 and the second mounting groove 6 are grooves, and the included angle between two adjacent first mounting grooves 5 on the circumferential direction of the inner wall surface of the insulation layer 31 is 120°; the included angle between two adjacent second mounting grooves 6 on the circumferential direction of the outer wall surface of the insulation layer 31 is 120°; the first mounting grooves 5 and the second mounting grooves 6 are distributed at a 60° intersection on the insulation layer 31, such as... Figure 6 It can meet the representativeness of the measurement points and facilitate the installation and sealing of the measurement point leads.

[0073] In one feasible embodiment, the protective tube 1 further includes an upper connector 12 and a lower connector 13. The upper connector 12 is disposed at the first end of the heat insulation shell 11, and the lower connector 13 is disposed at the second end of the heat insulation shell 11. At least two test component assemblies 2 are disposed in the receiving cavity, and the test component assemblies 2 are disposed along the axial direction of the protective tube 1. The thickness of the first filling layer 32 of the fuel short rod 20 in the upper test component assembly 2 is greater than the thickness of the first filling layer 32 of the fuel short rod 20 in the middle test component assembly 2. The thickness of the first filling layer 32 of the fuel short rod 20 in the upper test component assembly 2 is greater than the thickness of the first filling layer 32 of the fuel short rod 20 in the lower test component assembly 2.

[0074] In this technical solution, the thickness of the first thermal resistance layer 3 outside the fuel short rod 20 is set according to the axial position of the test component assembly 2 where the fuel short rod 20 is located. The upper test component assembly 2 is located in the containment cavity near the upper connector 12, and is located at the top of the reactor, with a lower heat release rate. The middle test component assembly 2 is located in the middle of the containment cavity, and is located at the middle of the reactor, the hottest position in the core, with a higher heat release rate. The lower test component assembly 2 is located in the containment cavity near the lower connector 13, and is located at the bottom of the reactor core. The lower part of the reactor, which is closer to the core, has a higher heat release rate. By making the first filling layer 32 of the fuel short rods 20 in the upper test component assembly 2 thicker, and the first filling layer 32 of the fuel short rods 20 in the middle and lower test component assemblies 2 thinner, the overall heat transfer characteristics of the test device can be controlled. This ensures that the fuel short rods 20 in each position reach similar operating temperatures under different heat release rates, which is beneficial for precise temperature control of the test device. In turn, it helps to accurately evaluate the behavior of materials in different thermal environments and optimize the design and operation of the nuclear reactor.

[0075] like Figure 1 and Figure 7 As shown, in one feasible embodiment, several test component assemblies 2 are arranged at equal intervals along the axial direction of the protective tube 1 in the receiving cavity; fuel short rods 20 are evenly arranged along the circumference of the protective tube 1 in the receiving cavity.

[0076] In this technical solution, multiple test component assemblies 2 are arranged axially inside the protection tube 1, with equal spacing between adjacent test component assemblies 2, to detect the temperature at different axial positions when the test device is working. This ensures the uniformity of power distribution within the reactor core, avoids local overheating or power peaks, and thus improves the thermal performance and fuel utilization of the fuel core 21. Each test component assembly 2 is equipped with multiple fuel short rods 20, which are used to detect the temperature at different circumferential positions when the test device is working. This helps to accurately control the neutron flux, achieve fine control of the reaction, and help evaluate the performance of the reactor core and optimize the reactor core design.

[0077] like Figure 8 As shown, in one feasible embodiment, the heat insulation shell 11 includes a shell body 111; the second thermal resistance layer 7 is disposed on the outer side of the shell body 111 along the circumferential direction of the shell body 111.

[0078] In this technical solution, a second thermal resistance layer 7 is added outside the casing body 111 to establish an approximately insulating layer between the coolant inside the protective tube 1 and the external coolant, so that the temperature gradient between the coolant inside the tube and the external coolant is maintained.

[0079] Furthermore, such as Figure 8 The heat insulation shell 11 also includes an upper sleeve 112 and a lower sleeve 113. The upper sleeve 112 and the lower sleeve 113 are located at both ends of the shell body 111. The upper sleeve 112 connects to the upper connector 12 at one end of the shell body 111, and the lower sleeve 113 connects the other end of the shell body 111 to the lower connector 13.

[0080] like Figure 8 As shown, in one feasible embodiment, the second thermal resistance layer 7 includes: an outer sleeve 71 and a third filling layer 72; the outer sleeve 71 is disposed circumferentially on the outside of the casing body 111, the outer sleeve 71 is sealed to the casing body 111, and a third gap exists between the inner wall of the outer sleeve 71 and the outer wall of the casing body 111; the third filling layer 72 is disposed in the third gap, and the third filling layer 72 is attached to the outer sleeve 71 and the casing body 111.

[0081] In this technical solution, the third filling layer 72 and the outer sleeve 71 are arranged sequentially from the inside to the outside of the shell body 111. By setting the third filling layer 72, a large temperature gradient is established between the inner cavity coolant and the outer coolant. At the same time, the third filling layer 72 isolates the physical contact between the outer sleeve 71 and the shell body 111, so that the inner cavity coolant water temperature and the outer coolant water temperature maintain a gradient difference.

[0082] Furthermore, the outer casing 111 is made of stainless steel to protect the internal structure, and the outer casing 33 is made of stainless steel as the second boundary seal for the third filling layer 72 and as the second boundary for protecting the internal structure of the tube 1. The third filling layer 72 between the outer casing 71 and the outer casing 111 is formed by filling with graphite. The third filling layer 72 further insulates and maintains the temperature, avoiding the influence of contact thermal resistance on the accuracy of the overall temperature field establishment of the test device.

[0083] like Figure 8 As shown, in one feasible embodiment, the high-temperature irradiation test device inside the fuel short rod reactor further includes: an open annulus plug 8 and a closed annulus plug 9; the open annulus plug 8 includes a filling port, the open annulus plug 8 is disposed circumferentially along the outer casing body 111 at the first end of the outer casing tube 71, and the closed annulus plug 9 is sealed to the outer casing body 111 and the outer casing tube 71; the closed annulus plug 9 is disposed circumferentially along the outer casing body 111 at the second end of the outer casing tube 71, and the closed annulus plug 9 is sealed to the outer casing body 111 and the outer casing tube 71.

[0084] In this technical solution, the closed ring plug 9, the open ring plug 8, the shell body 111, and the outer tube 71 form a cavity with an annular cross-section. Filling material is injected into the cavity through the opening on the open ring plug 8, and then the opening of the open ring plug 8 is sealed to form a third filling layer 72 between the shell body 111 and the outer tube 71, which isolates the shell body 111 and the outer tube 71 and helps to increase the temperature gradient difference between the inner cavity coolant and the outer coolant.

[0085] As a preferred option, flexible graphite is selected. After being injected into the annular cavity as the material of the third filling layer 72, the gap between the flexible graphite and the shell body 111 and the outer tube 71 is eliminated by mechanical extrusion to maintain close contact.

[0086] like Figure 9 As shown, according to a second aspect of this application, a method for manufacturing a high-temperature irradiation test device for a fuel short rod reactor is provided, for manufacturing a high-temperature irradiation test device for a fuel short rod reactor as described in any of the above technical solutions. The manufacturing method includes:

[0087] Based on fuel phase volume and U 235 Enrichment is used to design the core loading and control the neutron flux level and line power density of fuel rod 20;

[0088] Based on the core loading design values, calculate the accurate fuel heat release rate and line power, design the dimensions of the fuel short rod 20, and design the dimensions of the first thermal resistance layer 3;

[0089] An experiment was conducted using an electric heating tube with the same line power density instead of the fuel rod 20, and the temperature gradient inside and outside the first thermal resistance layer 3 was measured under the designed line power.

[0090] Remove the electric heating tube, install fuel short rod 20, and seal the irradiation device.

[0091] The method for fabricating a high-temperature irradiation test device for fuel short rod reactors provided in this application firstly determines the fuel phase volume and U... 235 The enrichment level is used to design the core loading, and the neutron flux level of the fuel rod 20 is controlled to ensure that the linear power density of the fuel rod 20 is not less than 15 kW / m. Then, based on the core loading results, the accurate fuel heat release rate and linear power are calculated, and a high-temperature irradiation test device for the fuel rod in the reactor is designed, including the inner and outer diameters of the first thermal resistance layer 3. For the design scheme, an electric heating tube with the same power density is selected as a substitute for the fuel rod 20, and a temperature sensor is implanted to measure whether the temperature gradient inside and outside the ceramic layer under the designed linear power is consistent with the design value. After removing the temperature sensor and the electric heating tube, the fuel rod 20 is installed and the test piece is sealed, and the high-temperature irradiation test of the fuel rod 20 in the reactor can be carried out.

[0092] In one feasible implementation, the inner and outer diameters of the heat insulation layer 31 are designed according to the axial position of the fuel rod 20 in the inner coolant cavity.

[0093] In this technical solution, the inner and outer diameters of the insulation layer 31 are designed in sections according to the upper test component 2, the middle test component 2, and the lower test position, so as to reduce the temperature difference caused by uneven axial power.

[0094] It is understood that the method for manufacturing the high-temperature irradiation test device in a fuel short rod reactor provided in this application embodiment, since it is applied to the high-temperature irradiation test device in a fuel short rod reactor as described in any of the above technical solutions, therefore the method for manufacturing the high-temperature irradiation test device in a fuel short rod reactor possesses all the beneficial effects of the high-temperature irradiation test device in a fuel short rod reactor as described in the above technical solutions.

[0095] Example:

[0096] The experimental apparatus is designed according to the manufacturing method, such as... Figure 10As shown, the protective tube contains four test component assemblies, each consisting of three fuel rods. The total length of the fuel rods is L2 = 160 mm, the radius of the fuel core is r1 = 2.425 mm, and helium is filled between the fuel core and the rod sheath. The inner diameter of the rod sheath is r2 = 3 mm. A ceramic insulation layer is installed outside the rod sheath, with an inner diameter r3 = 3.015 mm and an outer diameter r4 = 4.515 mm. Helium is filled between the ceramic insulation layer and the rod sheath. A stainless steel outer sheath is installed outside the ceramic insulation layer, with an inner diameter r5 = 4.53 mm and an outer diameter r6 = 5.53 mm. Five detection points were set at the same axial position every L1 = 35 mm on the fuel rod to detect the temperature of the inner wall of the fuel rod cladding, the inner and outer walls of the ceramic insulation layer, and the inner and outer walls of the stainless steel outer cladding. The measured inner wall temperature of the fuel rod cladding with the first thermal resistance layer was about 73% higher than that of the fuel rod without the first thermal resistance layer, and the average temperature of the external coolant was about 60% lower. This increased the upper limit of the irradiation test temperature of the fuel rod in the reactor, and enabled the successful conduct of high-temperature irradiation tests of fuel rods in low-temperature coolant.

[0097] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0098] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A fuel short rod in-pile high temperature irradiation test device, characterized in that: The fuel short rod in-pile high temperature irradiation test device comprises: A protective tube, the protective tube comprising a thermal insulation shell; A test piece assembly, the test piece assembly is arranged in a containing cavity surrounded by the thermal insulation cladding, the test piece assembly includes a plurality of fuel short rods, and the fuel short rods are arranged parallel to the axis of the thermal insulation cladding; A first thermal resistance layer is provided along the circumference of the fuel short rod, and the first thermal resistance layer is located between the fuel short rod and the thermal insulation cladding.

2. A fuel short rod in-pile high temperature irradiation test device according to claim 1, characterized in that: The first thermal resistance layer comprises: A heat insulation layer, wherein the heat insulation layer is arranged on the outside of the fuel short rod along the circumference of the fuel short rod, the heat insulation layer is sealed and connected to the fuel short rod, and a first gap exists between the inner side wall of the heat insulation layer and the outer side wall of the fuel short rod; a first filling layer, the first filling layer being arranged in the first gap, the first filling layer being in contact with the thermal insulation layer and the fuel short rods; An outer cladding, wherein the outer cladding is arranged on the outer side of the thermal insulation layer along the circumference of the fuel short rod, the outer cladding is sealed and connected to the thermal insulation layer, and a second gap exists between the inner side wall of the outer cladding and the outer side wall of the thermal insulation layer; A second filling layer, wherein the second filling layer is arranged in the second gap, and the second filling layer is in contact with the outer shell and the heat insulation layer.

3. The fuel short rod in-pile high temperature irradiation test device according to claim 2, characterized in that: The fuel short rod in-pile high temperature irradiation test device also includes: A first mounting groove, the first mounting groove is evenly arranged on the inner side wall of the thermal insulation layer along the circumference of the thermal insulation layer, and the first mounting groove is used to install a temperature monitoring device; The second mounting groove is evenly arranged on the outer wall of the thermal insulation layer along the circumference of the thermal insulation layer, the second mounting groove is used to install a temperature monitoring device, and the second mounting groove is staggered with the first mounting groove.

4. The fuel short rod in-pile high temperature irradiation test device according to claim 2, characterized in that: The protection tube further comprises an upper joint and a lower joint, wherein the upper joint is arranged at the first end of the thermal insulation shell, and the lower joint is arranged at the second end of the thermal insulation shell; At least two test piece assemblies are arranged in the accommodating cavity, and the test piece assemblies are arranged along the axial direction of the protective tube; the thickness of the first filling layer of the fuel short rods in the upper test piece assembly is greater than the thickness of the first filling layer of the fuel short rods in the middle test piece assembly; the thickness of the first filling layer of the fuel short rods in the upper test piece assembly is greater than the thickness of the first filling layer of the fuel short rods in the lower test piece assembly.

5. The fuel short rod in-pile high temperature irradiation test device according to claim 1, characterized in that: A plurality of the test piece assemblies are arranged in the accommodating cavity at equal intervals along the axial direction of the protection tube; The fuel short rods are evenly arranged in the accommodating cavity along the circumference of the protection tube.

6. The fuel short rod in-pile high temperature irradiation test device according to claim 1, characterized in that: The thermal insulation cladding comprises a cladding body; A second thermal resistance layer is arranged on the outer side of the cladding body along the circumference of the cladding body.

7. The fuel short rod in-pile high temperature irradiation test device according to claim 6, characterized in that: The second thermal resistance layer comprises: An outer sleeve, wherein the outer sleeve is arranged outside the cladding body along the circumferential direction of the cladding body, the outer sleeve is sealed and connected to the cladding body, and a third gap exists between the inner side wall of the outer sleeve and the outer side wall of the cladding body; A third filling layer is disposed in the third gap, and the third filling layer is in contact with the outer sleeve and the cladding body.

8. The fuel short rod in-pile high temperature irradiation test device according to claim 7, characterized in that: The fuel short rod in-pile high temperature irradiation test device also includes: An open ring plug, the open ring plug comprising a filling port, the open ring plug being arranged at a first end of the outer sleeve along the circumference of the cladding body, the closed ring plug being sealingly connected to the cladding body and the outer sleeve; A closed ring plug is arranged at the second end of the outer sleeve along the circumference of the cladding body, and the closed ring plug is sealed and connected to the cladding body and the outer sleeve.

9. A method for manufacturing a fuel short rod in-pile high temperature irradiation test device, characterized in that: Used to manufacture a fuel short rod in-pile high temperature irradiation test device as claimed in any one of claims 1 to 8, the manufacturing method comprising: According to the fuel phase volume and U 235 The core loading is designed based on the enrichment level to control the neutron flux level and linear power density of the fuel short rods; According to the core loading design value, calculate the accurate fuel heat release rate and linear power, design the size of the fuel short rods, and design the size of the first thermal resistance layer; The test was carried out by replacing the fuel short rod with an electric heating tube of the same linear power density, and measuring the temperature gradient inside and outside the first thermal resistance layer under the designed linear power; Remove the electric heating tubes, install the fuel rods, and package the irradiation device.

10. The method for manufacturing a fuel short rod in-pile high temperature irradiation test device according to claim 9, characterized in that: The inner diameter and outer diameter of the thermal insulation layer are designed according to the axial position of the fuel short rod in the inner coolant cavity.

Images