A fuel assembly irradiation device for fuel pins

Abstract

The application discloses a kind of suitable for fuel short stick's with stack fuel irradiation device, including device section and test section;The device section includes sequentially connected from top to bottom flange, water inlet pipe and guide pipe, flange closes the upper end of water inlet pipe, the lateral wall of water inlet pipe is opened with water inlet, flow regulating assembly is equipped in water inlet pipe, the flow regulating assembly is used to adjust water inlet opening degree;The test section includes sequentially connected upper joint, outer sleeve and lower joint, the upper joint is movably sleeved in guide pipe and forms sealed connection with it, the outer sleeve is sequentially loaded with test section, throttle plug and mixer from top to bottom in it, the throttle plug is used to produce throttling effect when cooling water passes, the mixer is used to produce stirring effect to cooling water after passing throttle plug.The application can be used in water-cooled research reactor to carry out with stack fuel irradiation test for shortened fuel rod, with the advantages of low cost, test mode flexible, meet the needs of multiple batches large quantities of sample test.

Description

Technical Field

[0001] This invention relates to the field of research reactor irradiation testing technology, specifically to a reactor fuel irradiation device suitable for water-cooled research reactors and fuel stubs. Background Technology

[0002] Because the development cycle of new nuclear fuels is very long, different types of off-pile and in-pile irradiation tests are required for performance studies and process screening for nuclear fuels with different technology maturity levels. For nuclear fuels that have passed proof-of-concept testing, a large number of in-pile irradiation tests and post-irradiation verifications are needed before formally conducting irradiation tests in a prototype reactor environment to obtain fuel performance parameters after irradiation and to screen and verify fuel element manufacturing processes. At this point, conducting in-pile fuel irradiation tests using a research reactor becomes a reasonable choice. In-pile irradiation tests are generally used to study the effects of fuel burnup and irradiation test temperature on test fuel elements. Directly introducing the research reactor's cooling water to cool the irradiated test specimen containing the test fuel elements has the advantages of low cost, flexible testing methods, and meeting the needs of multiple batches of large-scale sample testing. It is the conventional method for conducting nuclear fuel irradiation tests in water-cooled research reactors.

[0003] Because the water temperature in the water-cooled research reactor is relatively low, the core cooling water pressure differential varies in different furnace sections. The in-reactor fuel irradiation device needs to meet the cooling flow requirements of the test fuel elements within the range of core pressure differential variations, and also possess flexible cooling water flow adjustment capabilities. Considering the need for underwater transfer of the test fuel elements at the end of the irradiation test, the in-reactor fuel irradiation device needs to adopt a design that facilitates the separation of the fuel-containing test section, ensures a good dynamic seal between the test section and the device section, and ensures uniform mixing of the cooling water at the outlet of the test section. Summary of the Invention

[0004] The purpose of this invention is to provide a reactor-in-reactor fuel irradiation device suitable for short fuel rods in conducting reactor-in-reactor fuel irradiation tests on shortened fuel rods in a water-cooled research reactor. This device achieves a test section design that can accommodate short fuel rods, enables effective regulation of cooling water flow within the device, ensures good dynamic sealing between the test section and the device section, and has good ability to mix the cooling water in the test section, thereby helping to improve the test quality of reactor-in-reactor fuel irradiation tests.

[0005] This invention is achieved through the following technical solution:

[0006] The present invention provides a reactor fuel irradiation device suitable for fuel short rods, comprising a device section and a test section; the device section includes a flange, a water inlet pipe and a guide pipe connected sequentially from top to bottom, the flange closes the upper end of the water inlet pipe, the side wall of the water inlet pipe has a water inlet, and a flow regulating component is provided in the water inlet pipe for adjusting the opening degree of the water inlet.

[0007] The test section includes an upper connector, an outer sleeve, and a lower connector connected in sequence. The upper connector is movably fitted inside the guide tube and forms a sealed connection with it. The outer sleeve contains, from top to bottom, a test section, a throttling plug, and a mixer. The throttling plug is used to throttle the cooling water as it passes through, and the mixer is used to mix the cooling water after it passes through the throttling plug.

[0008] In the above technical solution, since the inlet pipe of the device section is equipped with a flow regulating component, the opening of the inlet can be adjusted, thereby flexibly regulating the flow rate of cooling water entering the device; since the upper joint of the test section extends into the guide pipe of the device section and the two form a gap seal connection, it is convenient to separate the test section and ensure a good dynamic seal between the test section and the device section; by setting a throttle plug and a mixer in the outer sleeve of the test section, the throttle plug can adjust the flow resistance coefficient of the cooling water, and the mixer can make the cooling water at the outlet of the test section more uniformly mixed, which can improve the test quality of the reactor fuel irradiation test.

[0009] As a preferred embodiment of the present invention, the flow regulating assembly includes a slider and a control rod. The slider is sleeved inside the water inlet pipe, and the outer wall of the slider cooperates with the inner wall of the water inlet pipe. The control rod passes through the flange and is connected to the slider. The control rod is used to drive the slider to move axially so as to change the amount of obstruction of the slider to the water inlet.

[0010] In the above technical solution, the slider can be dragged along the water inlet pipe by the control rod, thereby blocking the actual water inlet area, changing the flow resistance of the water inlet, and thus adjusting the flow rate of cooling water entering the device.

[0011] As a preferred embodiment of the present invention, there are multiple water inlets evenly distributed along the circumference on the water inlet pipe. The water inlets are square stepped holes that are larger at the top and smaller at the bottom, or inverted triangular holes, or the boundaries of the water inlets are parabolic.

[0012] As a preferred embodiment of the present invention, the outer wall of the upper connector is provided with annular sealing teeth, and the sealing teeth are in clearance sealing fit with the inner wall of the guide tube; or the inner wall of the guide tube is provided with annular sealing teeth, and the sealing teeth are in clearance sealing fit with the outer wall of the upper connector.

[0013] In the above technical solution, multiple annular sealing teeth are arranged at intervals along the axial direction to form a multi-tooth labyrinth structure. The tooth tip of the sealing tooth is in clearance fit with the wall surface of the corresponding component, so as to realize the movable connection between the device section and the test section, and at the same time, the gap between the two can be sealed. The structure of the sealing teeth mainly increases the resistance to cooling water flow, so as to prevent the cooling water in the device from flowing out through the gap between the upper connector and the guide pipe, or the cooling water outside the device from entering the device.

[0014] As a preferred embodiment of the present invention, the tooth shape of the sealing tooth is one of rectangle, triangle, trapezoid, and rhombus.

[0015] As a preferred embodiment of the present invention, the throttle plug is a cylindrical structure with a hole in the middle, the upper end of the throttle plug is a conical structure, the lower end is a concave conical structure, three legs are provided at both ends of the throttle plug, and multiple rectangular teeth are provided on the outer wall of the throttle plug along the circumference, with the top of the rectangular teeth having a clearance fit with the inner wall of the outer sleeve.

[0016] In the above technical solution, the multi-tooth labyrinth structure composed of multiple annular rectangular teeth arranged at intervals along the axial direction of the throttle plug is the main flow resistance component of the throttle plug. By modifying the axial spacing of the rectangular teeth, the gap between the top of the rectangular teeth and the inner wall of the outer sleeve, and the number of rectangular teeth, the flow resistance coefficient of the throttle plug can be significantly adjusted, thereby matching the cooling water flow requirements of different test sections. At the same time, because the cone at the upper end of the throttle plug can guide the cooling water towards the side wall, it will not form eddies between the test section and the upper end of the throttle plug, reducing the impact force of the cooling water on the throttle plug. When the cooling water flows between the throttle plug and the mixer, the presence of the conical cavity at the lower part of the throttle plug increases the cavity before the cooling water enters the mixer, avoiding direct impact of the cooling water on the upper end of the mixer.

[0017] As a preferred embodiment of the present invention, the throttle plug has 3 to 6 rectangular teeth, the cone angles of the convex and concave cones at the upper and lower ends are 30° to 48°, and the top of the rectangular teeth has a gap of 0.1 mm to 0.2 mm with the inner wall of the outer sleeve.

[0018] As a preferred embodiment of the present invention, the mixer includes a tube body, a top plate and an impeller. The outer wall of the tube body and the inner wall of the outer sleeve are clearance-fitted. The top plate is welded to both ends of the tube body. The top plate has through holes. A hollow tube is welded between the top plates. The impeller is rotatably mounted on the hollow tube.

[0019] In the above technical solution, since the impeller can rotate around the hollow tube welded between the top plates, it can better mix the cooling water, making the cooling water more thoroughly mixed.

[0020] As a preferred embodiment of the present invention, the test section includes a fixing plate, clamping blocks and a test piece, two clamping blocks are installed between the two fixing plates, the two ends of the clamping blocks are inserted into the through holes of the fixing plates, the test piece is installed between the two clamping blocks, and the outer wall of the test piece and the clamping blocks form an annular cooling water flow channel.

[0021] As a preferred embodiment of the present invention, the flange is provided with pressure tap A and pressure tap B; pressure tap A passes through the entire test section and passes through the throttle plug and mixer in sequence, with its outlet located inside the lower connector; the outlet of pressure tap B is located at the upper end of the upper connector.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] 1. The fuel irradiation device of the present invention is equipped with a toothed upper connector and a throttling plug, which can solve the leakage problem of the device on the one hand, and the throttling plug has a wide range of resistance parameters to meet different test requirements on the other hand.

[0024] 2. The in-reactor fuel irradiation device of the present invention has the ability to meet the cooling flow requirements of the test fuel element within the range of core pressure difference variation, and has flexible cooling water flow adjustment capability.

[0025] 3. The in-reactor fuel irradiation device of the present invention has the advantages of low cost, flexible testing methods, meeting the needs of multiple batches and large-volume sample testing, and conducting in-reactor fuel irradiation tests on shortened fuel rods;

[0026] 4. The reactor fuel irradiation device of the present invention has a good ability to mix the cooling water in the test section, which can improve the test quality of the reactor fuel irradiation test. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0028] Figure 1 This is a schematic diagram of the structure of the in-pile fuel irradiation device in this invention;

[0029] Figure 2 This is a schematic diagram of the upper connector structure in this invention;

[0030] Figure 3 This is a schematic diagram of the water inlet pipe structure in this invention;

[0031] Figure 4This is a schematic diagram of the throttle plug structure in this invention;

[0032] Figure 5 This is a schematic cross-sectional view of the throttle plug in this invention;

[0033] Figure 6 This is a schematic diagram of the mixer end structure in this invention;

[0034] Figure 7 For the present invention Figure 6 A schematic diagram of the AA cross-sectional structure in the diagram;

[0035] Figure 8 This is a schematic diagram of the impeller structure in this invention;

[0036] Figure 9 This is a schematic diagram of another guide tube structure in the present invention;

[0037] Figure 10 For the present invention Figure 1 A schematic diagram of the device section.

[0038] The attached diagram shows the markings and corresponding component names:

[0039] 1-Flange; 2-Flow regulating assembly; 21-Slider; 22-Control rod; 3-Inlet pipe; 31-Inlet; 4-Guide pipe; 41-Sealing tooth; 5-Upper connector; 51-Sealing tooth; 6-Outer sleeve; 7-Test piece; 8-Fixing plate; 9-Clamping block; 10-Throttle plug; 101-Support leg; 102-Rectangular tooth; 11-Mixer; 111-Pipe body; 112-Top plate; 113-Hollow pipe; 12-Impeller; 13-Lower connector; 14-Pressure tap A; 15-Pressure tap B. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0042] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0043] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0044] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0045] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0046] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0047] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to 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 the embodiments of this application.

[0048] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0049] Because the water temperature in the water-cooled research reactor is relatively low, the core cooling water pressure differential varies in different furnace sections. The in-reactor fuel irradiation device needs to meet the cooling flow requirements of the test fuel elements within the range of core pressure differential variations, and also possess flexible cooling water flow adjustment capabilities. Considering the need for underwater transfer of the test fuel elements at the end of the irradiation test, the in-reactor fuel irradiation device needs to adopt a design that facilitates the separation of the fuel-containing test section, ensures a good dynamic seal between the test section and the device section, and ensures uniform mixing of the cooling water at the outlet of the test section.

[0050] Based on this, the applicant, through in-depth research, invented a reactor fuel irradiation device suitable for short fuel rods. It can be used to conduct reactor fuel irradiation tests on shortened fuel rods in water-cooled research reactors. It achieves a test section design that can accommodate short fuel rods, enables effective regulation of cooling water flow within the device, ensures good dynamic sealing between the test section and the device, and has good ability to mix the cooling water in the test section, thereby helping to improve the test quality of reactor fuel irradiation tests.

[0051] Please refer to Figures 1 to 10 This application provides a reactor fuel irradiation device suitable for fuel short rods, comprising a device section and a test section; the device section includes a flange 1, a water inlet pipe 3 and a guide pipe 4 connected sequentially from top to bottom, the flange 1 closes the upper end of the water inlet pipe 3, the side wall of the water inlet pipe 3 has a water inlet 31, and the water inlet pipe 3 is provided with a flow regulating component 2, which is used to regulate the opening degree of the water inlet 31;

[0052] The test section includes an upper connector 5, an outer sleeve 6, and a lower connector 13 connected in sequence. The upper connector 5 is movably fitted inside the guide tube 4 and forms a sealed connection with it. The outer sleeve 6 contains, from top to bottom, a test section, a throttling plug 10, and a mixer 11. The throttling plug 10 is used to throttle the cooling water as it passes through, and the mixer 11 is used to mix the cooling water after it passes through the throttling plug 10.

[0053] In this embodiment, flanges 1 and guide pipes 4 are welded to the upper and lower ends of the inlet pipe 3, respectively. The upper connector 5 and lower connector 13 are welded to the upper and lower ends of the outer sleeve 6, respectively, forming a cavity inside the outer sleeve 6. The test section, throttle plug 10, and mixer 11 are installed sequentially from top to bottom in the cavity of the outer sleeve 6, with the mixer 11 arranged next to the lower connector 13. In this embodiment, the test section and the device section are detachably connected, specifically by inserting the upper connector 5 at the upper end of the test section into the guide pipe 4 at the lower end of the device section, and the two can form a dynamic sealing effect.

[0054] The flange 1 of the device section is fixed to the upper part of the research reactor pressure vessel. The lower part of the device section is connected to the test section. The lower connector 13 of the test section is inserted into the lower grid diaphragm of the reactor core. The test section within the test section is located in the active zone of the reactor core. During the reactor-on-reactor irradiation test, all structures of the device except flange 1 are immersed in the main cooling water of the research reactor. The cooling water of the research reactor flows in from the inlet 31 on the side of the inlet pipe 3 of the device section, flows through the guide pipe 4, the upper connector 5, the test section, the throttle plug 10, the mixer 11, and finally flows out of the device through the lower connector 13.

[0055] Because the inlet pipe 3 of the device section is equipped with a flow regulating component 2, the opening of the inlet 31 can be adjusted, thereby flexibly regulating the flow rate of cooling water entering the device; because the upper connector 5 of the test section extends into the guide pipe 4 of the device section and the two form a gap seal connection, it is convenient to separate the test section and ensure a good dynamic seal between the test section and the device section; by setting a throttle plug 10 and a mixer 11 in the outer sleeve 6 of the test section, the throttle plug 10 can adjust the flow resistance coefficient of the cooling water, and the mixer 11 can make the cooling water at the outlet of the test section more uniformly mixed, which can improve the test quality of the reactor fuel irradiation test.

[0056] According to some embodiments of this application, the flow regulating component 2 includes a slider 21 and a control rod 22. The slider 21 is sleeved inside the water inlet pipe 3, and the outer wall of the slider 21 cooperates with the inner wall of the water inlet pipe 3. The control rod 22 passes through the flange 1 and is connected to the slider 21. The control rod 22 is used to drive the slider 21 to move axially so as to change the blocking area of ​​the slider 21 on the water inlet 31.

[0057] Specifically, the flow regulating component 2 is installed inside the water inlet pipe 3. The control rod 22 passes through the flange 1 and is connected to the slider 21. The slider 21 has a cylindrical structure. The outer wall of the slider 21 is clearance-fitted with the inner wall of the water inlet pipe 3. The flow regulating component 2 can move axially inside the water inlet pipe 3. When an external force is applied to the control rod 22, it can drive the slider 21 to move axially. The slider 21 adjusts the flow rate of cooling water by blocking part of the water inlet 31, thereby changing the actual water inlet area.

[0058] According to some embodiments of this application, there are multiple water inlets 31 evenly distributed circumferentially on the water inlet pipe 3. The water inlets 31 are square stepped holes with a larger top and a smaller bottom, or inverted triangular holes, or the boundaries of the water inlets are parabolic. In this embodiment, four water inlets 31 are opened circumferentially on the side wall of the water inlet pipe 3, and the water inlets 31 are connected to the outside of the device. Cooling water enters the inside of the device through the water inlets 31 and flows sequentially through the test section, the throttling plug 10 and the mixer 11.

[0059] Specifically, the inlet 31 can be a square stepped hole with a larger top and a smaller bottom. The stepped inlet 31 is composed of two rectangular segments of different widths in the axial direction, which makes the cooling water flow rate in the device change significantly. The opening degree of the inlet 31 and the cooling water flow rate curve have a large range of variation.

[0060] The inlet 31 on the inlet pipe 3 can also be an inverted triangle, or the inlet boundary can be parabolic. The control rod 22 and the slider 21 of the flow regulating component 2 are welded together. The axial position of the control rod 22 is changed by an external mechanism, thereby changing the axial position of the slider 21 to regulate the flow rate of cooling water into the device.

[0061] According to some embodiments of this application, the outer wall of the upper connector 5 is provided with annular sealing teeth 51, and the sealing teeth 51 are in clearance sealing fit with the inner wall of the guide tube 4; or the inner wall of the guide tube 4 is provided with annular sealing teeth 41, and the sealing teeth 41 are in clearance sealing fit with the outer wall of the upper connector 5.

[0062] In this embodiment, multiple annular sealing teeth 51 or 41 are arranged at intervals along the axial direction to form a multi-tooth labyrinth structure. The tooth tips of the sealing teeth 51 or 41 are clearance-fitted with the wall surface of the corresponding component, thereby effectively preventing core cooling water from leaking into the test section through the movable connection while realizing the movable connection between the device section and the test section.

[0063] In this embodiment, the upper connector 5 is a hollow reducing pipe. It should be noted that the upper connector 5 is also a lifting head. Annular rectangular sealing teeth 51 are machined on the outer wall of the straight section of the upper connector 5, and the rectangular sealing teeth 51 are clearance-fitted with the inner wall of the guide pipe 4. Alternatively, rectangular sealing teeth 41 can be machined on the inner wall of the guide pipe 4. The outer wall of the upper connector 5 is smooth. The entire irradiation device is divided into two parts: the upper connector 5 and below constitute the testing section, and the upper connector 5 and above constitute the device section. The testing section and the device section are connected by a dynamic seal between the guide pipe 4 and the upper connector 5.

[0064] According to some embodiments of this application, the sealing teeth 51 or 41 have a tooth shape that is rectangular, triangular, trapezoidal, or rhomboid. The sealing teeth 51 or 41 on the upper connector 5 or guide pipe 4 can adopt any of the above-mentioned tooth shapes, but the gap between the sealing teeth 51 or 41 and the wall surface needs to be carefully controlled. The structure of the sealing teeth 51 or 41 is mainly to increase the resistance to cooling water flow, preventing cooling water inside the device from flowing out through the gap between the upper connector 5 and the guide pipe 4, or preventing cooling water from outside the device from entering the device.

[0065] According to some embodiments of this application, the flange 1 is provided with a pressure tap A14 and a pressure tap B15; the pressure tap A14 passes through the entire test section and passes through the throttle plug 10 and the mixer 11 in sequence, and the outlet is located inside the lower connector 13; the outlet of the pressure tap B15 is located at the upper end of the upper connector 5.

[0066] In this embodiment, one end of pressure tapping tube A14 and pressure tapping tube B15 are both connected to the pressure measuring system, and the other end enters the device from the guide tube 4. Since the outlets of pressure tapping tube A14 and pressure tapping tube B15 are located in different sections within the device, the pressure at those points can be measured. Based on theoretical calculations and by measuring the pressure difference between pressure tapping tube A14 and pressure tapping tube B15, the design rationality of the irradiation device is verified.

[0067] According to some embodiments of this application, the throttle plug 10 is a cylindrical structure with an axial through hole in the middle. The pressure tap A14 is inserted into the through hole on the throttle plug 10. The upper end of the throttle plug 10 is a convex conical structure, and the lower end is a concave conical structure. The two ends of the throttle plug 10 are respectively provided with three legs 101. The outer wall of the throttle plug 10 is provided with a plurality of rectangular teeth 102 along the circumferential direction. The top of the rectangular teeth 102 is in clearance fit with the inner wall of the outer sleeve 6.

[0068] In this embodiment, the multi-tooth labyrinth structure composed of multiple annular rectangular teeth 102 arranged at intervals along the axial direction of the throttle plug 10 is the main flow resistance part of the throttle plug 10. By changing the axial spacing of the rectangular teeth 102, the size of the gap between the top of the rectangular teeth 102 and the inner wall of the outer sleeve 6, and the number of rectangular teeth 102, the flow resistance coefficient of the throttle plug 10 can be greatly adjusted, thereby matching the cooling water flow requirements of different test sections.

[0069] According to some embodiments of this application, the throttle plug 10 has 3 to 6 rectangular teeth 102, the cone angles of the convex and concave cones at the upper and lower ends are 30° to 48°, and the top of the rectangular teeth 102 has a gap of 0.1 mm to 0.2 mm between it and the inner wall of the outer sleeve 6.

[0070] During the test, cooling water flows through the throttle plug 10. Because the cone-shaped upper part of the throttle plug 10 guides the cooling water towards the sidewall, vortices are not formed between the test section and the upper part of the throttle plug 10, reducing the impact force of the cooling water on the throttle plug 10. When the cooling water flows between the throttle plug 10 and the mixer 11, the presence of the cone-shaped cavity at the lower part of the throttle plug 10 increases the cavity before the cooling water enters the mixer 11, preventing the cooling water from directly impacting the upper part of the mixer 11. By rationally designing the throttle plug 10 and the test section, the drag of the test section can be matched with the core drag.

[0071] According to some embodiments of this application, the mixer 11 includes a tube body 111, a top plate 112, and an impeller 12. The outer wall of the tube body 111 is clearance-fitted with the inner wall of the outer sleeve 6. The top plate 112 is welded to both ends of the tube body 111. Water passage holes are opened on the top plate 112 to allow cooling water to pass through. A hollow tube 113 is welded between the two top plates 112. The impeller 12 is rotatably mounted on the hollow tube 113.

[0072] Specifically, the outer wall of the mixer 11 and the inner wall of the outer sleeve 6 are fitted with a clearance. The impeller 12 is mounted on a hollow tube 113 inside the tube body 111 of the mixer 11, and the pressure tapping tube A14 can pass through the hollow tube 113. It should be noted that a hole for the pressure tapping tube A14 to pass through is also made on the top plate 112. When cooling water flows through the mixer 11, the impeller 12 can rotate around the hollow tube 113 welded between the top plates 112, which provides better mixing of the cooling water and makes the cooling water more thoroughly mixed.

[0073] According to some embodiments of this application, the test section includes a fixing plate 8, a clamping block 9, and a test piece 7. Two clamping blocks 9 are installed between the two fixing plates 8. The two ends of the clamping blocks 9 are inserted into the through holes of the fixing plates 8. The test piece 7 is installed between the two clamping blocks 9. The outer wall of the test piece 7 and the clamping blocks 9 form an annular cooling water flow channel.

[0074] In this embodiment, the test section can consist of one or more layers, with pressure tap A passing through all the test sections. The test sections are mainly for fixing the test piece 7 and providing a reasonable cooling water channel for the test piece 7.

[0075] In this example, the in-reactor fuel irradiation device is divided into two parts: the upper connector 5 and below constitute the test section, while the upper connector 5 and above constitute the device section. The test section and the device section are connected by guide pipe 4 and upper connector 5. A specific fuel rod test method is provided below, with the test steps as follows:

[0076] 1. Complete the assembly of the irradiation device and install it inside the test reactor;

[0077] 2. The cooling water in the test reactor enters the device through the inlet 31 on the inlet pipe 3, flows into the test section along the inlet pipe 3 and the guide pipe 4, and passes through the test section, the throttle plug 10 and the mixer 11, and finally flows out from the lower connector 13.

[0078] 3. The design rationality of the irradiation device was verified by theoretical calculations and by measuring the pressure difference between pressure tube A14 and pressure tube B15.

[0079] 4. Based on the test requirements for cooling water, the opening of the inlet 31 on the inlet pipe 3 can be adjusted by adjusting the flow rate adjustment component 2, thereby adjusting the cooling water flow rate.

[0080] 5. After the cooling water is adjusted to a reasonable flow rate, the flow rate adjustment component 2 is mechanically locked to make the flow rate of cooling water entering the irradiation device a constant value.

[0081] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A reactor fuel irradiation device suitable for fuel short rods, characterized in that, It includes a device section and a test section; the device section includes a flange (1), an inlet pipe (3) and a guide pipe connected from top to bottom. The flange (1) closes the upper end of the inlet pipe (3). The side wall of the inlet pipe (3) has an inlet (31). The inlet pipe (3) is provided with a flow regulating component (2). The flow regulating component (2) is used to regulate the opening degree of the inlet (31). The test section includes an upper connector (5), an outer sleeve (6), and a lower connector (13) connected in sequence. The upper connector (5) is movably fitted inside the guide tube (4) and forms a sealed connection with it. The outer sleeve (6) contains, from top to bottom, a test section, a throttle plug (10), and a mixer (11). The throttle plug (10) is used to throttle the cooling water as it passes through, and the mixer (11) is used to stir the cooling water after it passes through the throttle plug (10). The throttle plug (10) is a cylindrical structure with a hole in the middle. The upper end of the throttle plug (10) is a conical structure, and the lower end is a concave conical structure. The two ends of the throttle plug (10) are respectively provided with three legs (101). The outer wall of the throttle plug (10) is provided with multiple rectangular teeth (102) along the circumferential direction. The top of the rectangular teeth (102) is in clearance fit with the inner wall of the outer sleeve (6).

2. The in-reactor fuel irradiation device for fuel short rods according to claim 1, characterized in that, The flow regulating component (2) includes a slider (21) and a control rod (22). The slider (21) is fitted inside the water inlet pipe (3). The outer wall of the slider (21) is matched with the inner wall of the water inlet pipe (3). The control rod (22) passes through the flange (1) and is connected to the slider (21). The control rod (22) is used to drive the slider (21) to move axially so as to change the amount of obstruction of the slider (21) to the water inlet (31).

3. The in-reactor fuel irradiation device for fuel short rods according to claim 1, characterized in that, The inlet (31) has multiple inlets and is evenly distributed along the circumference on the inlet pipe (3). The inlet (31) is a square stepped hole with a larger top and a smaller bottom, or an inverted triangular hole, or the boundary of the inlet (31) is parabolic.

4. The in-reactor fuel irradiation device for fuel short rods according to claim 1, characterized in that, The outer wall of the upper connector (5) is provided with an annular sealing tooth (51), and the sealing tooth (51) and the inner wall of the guide tube (4) are in a gap-sealed fit; or the inner wall of the guide tube (4) is provided with an annular sealing tooth (41), and the sealing tooth (41) and the outer wall of the upper connector (5) are in a gap-sealed fit.

5. The in-reactor fuel irradiation device for fuel short rods according to claim 4, characterized in that, The sealing teeth have a shape that is one of rectangle, triangle, trapezoid, or rhombus.

6. The in-reactor fuel irradiation device for fuel short rods according to claim 1, characterized in that, The throttle plug (10) has 3 to 6 rectangular teeth (102), and the cone angles of the convex and concave cones at the upper and lower ends are 30° to 48°. The top of the rectangular teeth (102) has a gap of 0.1 mm to 0.2 mm between it and the inner wall of the outer sleeve (6).

7. The in-reactor fuel irradiation device for fuel short rods according to claim 1, characterized in that, The mixer (11) includes a tube body (111), a top plate (112), and an impeller (12). The outer wall of the tube body (111) and the inner wall of the outer sleeve (6) are in clearance fit. The top plate (112) is welded to both ends of the tube body (111). The top plate (112) has through holes. A hollow tube (113) is welded between the top plates (112). The impeller (12) is rotatably mounted on the hollow tube (113).

8. The in-reactor fuel irradiation device for fuel short rods according to claim 1, characterized in that, The test section includes a fixed plate (8), a clamping block (9) and a test piece (7). Two clamping blocks (9) are installed between the two fixed plates (8). The two ends of the clamping blocks (9) are inserted into the through holes of the fixed plates (8). The test piece (7) is installed between the two clamping blocks (9). The outer wall of the test piece (7) and the clamping blocks (9) form an annular cooling water flow channel.

9. The in-reactor fuel irradiation device for fuel short rods according to claim 1, characterized in that, The flange (1) is provided with pressure tap A (14) and pressure tap B (15); the pressure tap A (14) passes through the entire test section and passes through the throttle plug (10) and mixer (11) in sequence, and the outlet is located inside the lower connector (13); the outlet of the pressure tap B (15) is located at the upper end of the upper connector (5).

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