Irradiation device

Abstract

This application discloses an irradiation device, relating to the field of research reactor fuel irradiation technology. Its main purpose is to create a neutron energy spectrum environment similar to that of a fast reactor within a thermal reactor, simulating the operating environment of fast reactor fuel elements in an actual reactor for irradiation experiments. The main technical solution of this application is as follows: The irradiation device includes: a positioning flange installed on the fixed structure at the top of the research reactor; a fuel rod assembly fixed relative to the positioning flange; a neutron screen assembly disposed outside the fuel rod assembly, with an axial hollow channel inside the neutron screen assembly, and the fuel rod assembly located within the hollow channel; and a driving assembly connected to the neutron screen assembly, used to drive the neutron screen assembly to rotate circumferentially and / or move axially relative to the fuel rod assembly.

Description

Technical Field

[0001] This application belongs to the field of research reactor fuel irradiation technology, specifically relating to an irradiation device. Background Technology

[0002] In recent years, nuclear energy development has received increasing attention, and fast neutron reactors (Fast Reactors), as the core component of fourth-generation advanced nuclear energy systems, are considered an important direction for future nuclear energy development due to their superior resource utilization and ability to reduce nuclear waste. To ensure the stable and safe operation of Fast Reactors, irradiation testing of their fuel elements is a crucial step.

[0003] The operating environment of fast reactor fuel elements in a real reactor is a special neutron energy spectrum environment. To simulate this environment and conduct irradiation tests on fuel elements, a research reactor with a similar neutron energy spectrum is usually required. However, due to the high cost of building and operating fast neutron research reactors, such research reactors are extremely scarce both domestically and internationally, resulting in a severe shortage of resources for fast reactor fuel element irradiation tests.

[0004] Traditional thermal spectroscopy research reactors cannot be directly used for irradiation tests of fast reactor fuel elements because their neutron energy spectra differ significantly from those of fast reactors. Summary of the Invention

[0005] In view of this, this application provides an irradiation device, the main purpose of which is to create a neutron energy spectrum environment similar to that of a fast reactor within a thermal reactor, so as to simulate the operating environment of fast reactor fuel elements in an actual reactor and to conduct irradiation tests.

[0006] To achieve the above objectives, this application mainly provides the following technical solutions:

[0007] This application provides an irradiation device, comprising:

[0008] A positioning flange, which is installed on the top fixing structure of the research stack;

[0009] A fuel rod assembly, which is fixed relative to the positioning flange;

[0010] A neutron screen assembly is disposed outside the fuel rod assembly, and an axial hollow channel is provided inside the neutron screen assembly, with the fuel rod assembly located inside the hollow channel;

[0011] A drive assembly connected to the neutron screen assembly, the drive assembly being used to drive the neutron screen assembly to rotate circumferentially and / or move axially relative to the fuel rod assembly.

[0012] Optionally, the fuel rod assembly includes:

[0013] Internal target tube and multiple fuel rods;

[0014] The inner target tube is provided with an upper cover at one end near the positioning flange, and the upper cover has an air outlet for connecting to an air outlet pipe. The inner target tube is provided with a lower cover at one end away from the positioning flange, and the lower cover has an air inlet for connecting to an air inlet pipe.

[0015] Multiple fuel rods are disposed inside the inner target tube. Positioning blocks are provided at both ends of the multiple fuel rods, and connecting blocks are provided between adjacent fuel rods. A through hole is provided at the center of each positioning block and the connecting block, and the through hole is used to allow gas to pass through.

[0016] Optionally, the inner target tube is a variable diameter tube, and the inner diameter of the inner target tube changes in a stepped manner along the first direction.

[0017] Optionally, at least two air inlets are provided, each air inlet is connected to an air inlet pipe, and different air inlets are used to pass through different types of gases.

[0018] Optionally, the neutron screen component includes:

[0019] Inner sleeve, outer sleeve and multi-segment neutron screen;

[0020] The inner sleeve is disposed inside the outer sleeve, and the two ends of the outer sleeve and the inner sleeve are sealed and connected by cover plates. The outer side of the inner sleeve, the inner side of the outer sleeve and the two cover plates constitute a sealed cavity, and multiple neutron screens are arranged sequentially along the axial direction in the sealed cavity.

[0021] Optionally, the neutron screens in each segment are made of different materials and have different thicknesses.

[0022] Optionally, the driving component includes:

[0023] Drive unit, transmission unit, and connecting unit;

[0024] The first end of the connecting part is connected to the transmission part, and the second end of the connecting part is connected to the neutron screen assembly. The transmission part is also connected to the driving part. The driving part is used to drive the transmission part to move, so as to drive the neutron screen assembly to rotate circumferentially and / or move axially through the connecting part.

[0025] Optionally, the driving part includes a first driving unit, and the transmission part includes a first cylindrical gear, a second cylindrical gear, a guide rod, and a guide tube;

[0026] The drive end of the first drive unit is connected to the first cylindrical gear, the second cylindrical gear meshes with the first cylindrical gear, and the guide rod is connected to the second cylindrical gear;

[0027] The first driving unit is used to drive the first cylindrical gear to rotate, and then drive the guide rod to rotate around the axis of the second cylindrical gear as the rotation center through the second cylindrical gear;

[0028] At least a portion of the guide rod is movably disposed within the guide tube, and the guide tube is connected to the connecting part, thereby driving the connecting part to rotate synchronously.

[0029] Optionally, the drive unit further includes a second drive unit, and the transmission unit further includes a bevel gear set, a lead screw shaft, and a driven shaft;

[0030] The driving end of the second driving unit is connected to the input end of the bevel gear set, and the output end of the bevel gear set is connected to the lead screw shaft. The lead screw shaft is engaged with the driven shaft through a pipe thread.

[0031] The second drive unit is used to drive the bevel gear set to rotate, so that the lead screw shaft drives the driven shaft to move axially. The driven shaft is connected to the connecting part to drive the connecting part to move axially.

[0032] Optionally, the connecting part includes a connecting flange and a connecting pipe. The connecting flange is used to fix the guide pipe, the driven shaft and the connecting pipe. The end of the connecting pipe away from the connecting flange is connected to the neutron screen assembly.

[0033] By employing the above technical solution, this application has at least the following beneficial effects:

[0034] The irradiation apparatus provided in the embodiments of this application, by setting up a neutron screen assembly, can create a locally approximate fast reactor neutron energy spectrum environment within a thermal spectral research reactor. This fully utilizes existing thermal spectral research reactor resources, reduces the cost of fast reactor fuel element irradiation tests, promotes the research, verification, and engineering application of fast reactor fuel technology, and further strengthens the development process of fast reactor fuel. Simultaneously, by setting up a driving assembly, the neutron screen assembly can be driven to rotate circumferentially and / or move axially relative to the fuel rod assembly, thereby changing the neutron flux distribution. This makes the neutron energy spectrum at the location of the fuel rod assembly closer to the neutron energy spectrum of a fast reactor, thus making the irradiation of the fuel element in the thermal spectral research reactor more closely resemble the actual situation in a fast reactor. This helps to more realistically study the performance changes of fast reactor fuel elements during irradiation, avoiding the problem of large deviations between experimental data and actual fast reactor operation due to excessive differences in neutron energy spectra, and providing more reliable data support for fast reactor fuel development. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of an irradiation device according to an optional embodiment of this application;

[0036] Figure 2 This is a schematic diagram of the structure of a fuel rod assembly according to an optional embodiment of this application;

[0037] Figure 3 This is a schematic diagram of the structure of a neutron screen component according to an optional embodiment of this application;

[0038] Figure 4 This is a schematic diagram of the structure of a driving component in an optional embodiment of this application.

[0039] The reference numerals in the attached figures are as follows:

[0040] 1. Positioning flange; 2. Fuel rod assembly; 21. Inner target tube; 22. Fuel rod; 23. Top cover; 231. Exhaust port; 24. Bottom cover; 241. Inlet port; 25. Positioning block; 26. Connecting block; 3. Neutron screen assembly; 31. Inner sleeve; 32. Outer sleeve; 33. Neutron screen; 34. Cover plate; 4. Drive assembly; 41. Drive unit; 411. First drive unit; 412. Second drive unit; 42. Transmission unit; 421. First cylindrical gear; 422. Second cylindrical gear; 423. Guide rod; 424. Guide tube; 425. Bevel gear set; 426. Lead screw shaft; 427. Driven shaft; 43. Connecting part; 431. Connecting flange; 432. Connecting tube. Detailed Implementation

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] See also Figures 1 to 4 As shown, according to an embodiment of this application, an irradiation device is provided, comprising: a positioning flange 1, which is installed on a fixed structure at the top of a research reactor; a fuel rod assembly 2, which is fixed relative to the positioning flange 1; a neutron screen assembly 3, which is disposed outside the fuel rod assembly 2 and has an axial hollow channel inside, with the fuel rod assembly 2 located within the hollow channel; and a drive assembly 4, which is connected to the neutron screen assembly 3 and is used to drive the neutron screen assembly 3 to rotate circumferentially and / or move axially relative to the fuel rod assembly 2.

[0046] In this embodiment, by setting up the neutron screen assembly 3, a local neutron energy spectrum environment approximating that of a fast reactor can be created within the thermal spectral research reactor. This fully utilizes existing thermal spectral research reactor resources, reduces the cost of fast reactor fuel element irradiation tests, promotes the research, verification, and engineering application of fast reactor fuel technology, and further strengthens the development process of fast reactor fuel. Simultaneously, by setting up the drive assembly 4, the neutron screen assembly 3 can be driven to rotate circumferentially and / or move axially relative to the fuel rod assembly 2, thereby changing the neutron flux distribution. This makes the neutron energy spectrum at the location of the fuel rod assembly 2 closer to the neutron energy spectrum of a fast reactor, thus making the irradiation of the fuel elements in the thermal spectral research reactor more closely resemble the actual situation in a fast reactor. This helps to more realistically study the performance changes of fast reactor fuel elements during irradiation, avoiding the problem of large deviations between experimental data and actual fast reactor operation due to excessive differences in neutron energy spectra, and providing more reliable data support for fast reactor fuel development.

[0047] The positioning flange 1 is a key component connecting the irradiation device to the research reactor. Its main function is to fix the irradiation device to the fixed structure on top of the research reactor, ensuring that the irradiation device remains stable during irradiation. In addition, an opening is designed in the middle of the positioning flange 1, which is mainly used to introduce the gas inlet pipe and the gas outlet pipe.

[0048] The fuel rod assembly 2 is the core component of the irradiation system, containing the fuel used for the irradiation test. In this embodiment, the relative fixation of the fuel rod assembly 2 and the positioning flange 1 is achieved by the traction effect of the inlet and outlet pipes. Specifically, the inlet and outlet pipes, passing through the positioning flange 1, can be connected to corresponding parts of the fuel rod assembly 2. By rationally designing the installation position, direction, and connection method of the inlet and outlet pipes, and utilizing their traction function, the fuel rod assembly 2 maintains a stable position relative to the positioning flange 1. This ensures that the fuel rod assembly 2 will not shift during the operation of the entire irradiation device, guaranteeing the accuracy and stability of the irradiation test.

[0049] The neutron screen assembly 3 is located outside the fuel rod assembly 2. Inside the neutron screen assembly 3 is an axially oriented hollow channel, within which the fuel rod assembly 2 is situated. The primary function of the neutron screen assembly 3 is to regulate the neutron flux and energy spectrum. It should be noted that the neutron screen assembly 3 acts like a "neutron filter." The neutron energy spectrum in a thermal spectroscopy research reactor differs from that in a fast reactor. The neutron screen assembly 3 can block some unwanted neutrons, allowing neutrons that better match the energy spectrum characteristics of a fast reactor to pass through. This creates a localized neutron energy spectrum environment within the hollow channel, approximating that of a fast reactor, enabling the fuel rod assembly 2 to be irradiated in this filtered neutron environment.

[0050] The driving component 4 is connected to the neutron screen component 3. The function of the driving component 4 is to drive the neutron screen component 3 to rotate circumferentially and / or move axially relative to the fuel rod assembly 2. In this embodiment, the driving component 4 can drive the neutron screen component 3 to rotate circumferentially relative to the fuel rod assembly 2; conversely, the driving component 4 can drive the neutron screen component 3 to move axially relative to the fuel rod assembly 2. Furthermore, the driving component 4 can simultaneously drive the neutron screen component 3 to rotate circumferentially and move axially relative to the fuel rod assembly 2. It should be noted that when the driving component 4 drives the neutron screen component 3 to rotate circumferentially, the neutron screen component 3 acts like a rotating sieve, changing the angle at which neutrons enter the hollow channel. For example, different rotation angles may cause neutrons to enter the hollow channel at different incident angles, thereby changing the neutron flux distribution around the fuel rod assembly 2. When the driving component 4 drives the neutron screen component 3 to move axially, it can change the position of the fuel rod assembly 2 within the hollow channel. This means that the neutron environment experienced by the fuel rod assembly 2 inside the neutron screen component 3 can be dynamically changed. For example, moving the fuel rod assembly 2 to different positions in the hollow channel may cause changes in the neutron flux and energy spectrum at the location of the fuel rod assembly 2 due to structural differences in the neutron screen assembly 3 in the axial direction (such as changes in the material thickness and composition of the neutron screen 33), thus providing researchers with a flexible means to adjust the irradiation conditions.

[0051] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 2 As shown, the fuel rod assembly 2 includes: an inner target tube 21 and multiple fuel rods 22; an upper cover 23 is provided at one end of the inner target tube 21 near the positioning flange 1, and the upper cover 23 has an outlet hole 231 for connecting to an outlet pipe; a lower cover 24 is provided at the other end of the inner target tube 21 away from the positioning flange 1, and the lower cover 24 has an inlet hole 241 for connecting to an inlet pipe; multiple fuel rods 22 are disposed inside the inner target tube 21, and positioning blocks 25 are provided at both ends of the multiple fuel rods 22, and a connecting block 26 is provided between two adjacent fuel rods 22; a through hole is provided at the center of both the positioning block 25 and the connecting block 26 for gas to pass through.

[0052] In this embodiment, an inlet port 241 and an outlet port 231 are respectively provided on the upper and lower covers 24 of the inner target tube 21, and the inlet and outlet pipes are connected to form a stable gas circulation channel. During irradiation, the fuel rod assembly 2 generates heat, and the gas can circulate through this channel to carry away the heat, thereby effectively preventing the fuel rod assembly 2 from being damaged due to overheating. For example, a large amount of heat is generated in some nuclear reactions, and this gas circulation system acts like a radiator, maintaining the fuel rod assembly 2 within a suitable temperature range.

[0053] The inner target tube 21 provides a relatively enclosed space for the fuel rod 22, which serves to protect and limit the position of the fuel rod 22.

[0054] Specifically, an upper cover 23 is provided at the end of the inner target tube 21 near the positioning flange 1. This upper cover 23 is a closed component of the inner target tube 21 near the positioning flange 1. The upper cover 23 has a vent 231, which is used to connect to the vent pipe. When the entire irradiation device is running, gas may need to be discharged from the inner target tube 21 due to various situations (such as some gaseous substances produced by the reaction of the fuel rod 22 or gas introduced for heat dissipation, etc.). At this time, the vent 231 can serve as a channel for gas discharge, guiding the gas to other parts of the device for subsequent processing through connection with the vent pipe. At the same time, a lower cover 24 is provided at the end of the inner target tube 21 away from the positioning flange 1. This lower cover 24 also serves to seal the inner target tube 21. The lower cover 24 has an inlet 241, which is used to connect to the inlet pipe. During irradiation, in order to achieve certain functions (such as introducing cooling gas for heat dissipation, or maintaining a certain gas environment inside the inner target tube 21), it is necessary to supply gas from the outside into the inner target tube 21. The air inlet 241 can serve as an air inlet channel. By connecting with the air inlet pipe, external gas can smoothly enter the interior of the inner target tube 21.

[0055] The fuel rod 22 is the core component involved in the nuclear reaction and related processes during the entire irradiation process. Specifically, the fuel rod 22 undergoes a series of reactions under conditions such as neutron irradiation, and the status of these reactions is a key focus of research and monitoring. In this embodiment, multiple fuel rods 22 are arranged sequentially along the axial direction within the inner target tube 21 to ensure that each fuel rod 22 receives uniform and effective radiation.

[0056] In this configuration, a positioning block 25 is provided between the fuel rod 22 closest to the upper cover 23 and the upper cover 23, and a positioning block 25 is also provided between the fuel rod 22 closest to the lower cover 24 and the lower cover 24. It is understood that by providing the positioning blocks 25, the accurate axial position of the fuel rod 22 within the inner target tube 21 can be ensured, preventing axial movement of the fuel rod 22 during irradiation. Simultaneously, the positioning blocks 25 also ensure the accurate radial position of the fuel rod 22 within the inner target tube 21, preventing radial movement of the fuel rod 22 during irradiation and thus preventing it from obstructing the gas passage.

[0057] In this design, a connecting block 26 is provided between adjacent fuel rods 22. The connecting block 26 divides the area within the inner target tube 21 into different fuel rod 22 cavities. Each fuel rod 22 cavity provides a relatively independent and stable operating environment for its contained fuel rod, facilitating more precise monitoring of the irradiation status of each fuel rod 22. Understandably, researchers can obtain detailed data on the irradiation process of each fuel rod 22, such as neutron flux and fission product formation, by placing corresponding sensors in different cavities. This is beneficial for in-depth analysis of the performance of individual fuel rods 22 and avoids the impact of mutual interference between adjacent fuel rods 22 on data accuracy.

[0058] Both the positioning block 25 and the connecting block 26 have through holes at their centers, allowing gas to smoothly enter the multiple fuel rod 22 chambers, thus effectively protecting and ensuring the stable operation of the fuel rods 22. When cooling gas enters the inner target tube 21 through the inlet 241, it flows between the chambers of each fuel rod 22. Due to the obstruction of the connecting block 26, the gas flow path in each chamber is relatively independent, allowing for more efficient removal of heat generated by the fuel rods 22. This ensures that each fuel rod 22 operates at a suitable temperature, reducing potential risks caused by localized overheating.

[0059] In the above embodiment, the inner target tube 21 is a variable diameter tube, and the inner diameter of the inner target tube 21 changes in a stepped manner along the first direction.

[0060] In this embodiment, when gas enters the inner target tube 21 through the inlet 241, its flow rate and direction change as it passes through regions with varying inner diameters. For example, in regions with smaller diameters, the gas flow rate increases, which helps enhance convective heat transfer between the gas and the fuel rods 22. The increased gas flow rate can more efficiently remove the heat generated by the fuel rods 22, improving heat dissipation efficiency and preventing the fuel rods 22 from being overheated and affecting their performance or causing damage. Moreover, this structure with varying inner diameters can guide the gas to form specific flow paths in different diameter regions, making the gas distribution around the fuel rods 22 more uniform. When the gas passes through regions with stepped changes in inner diameter, it creates a turbulence-like effect, prompting the gas to better contact all parts of the fuel rods 22, avoiding "dead zones" in gas flow, further optimizing the heat exchange process, and ensuring that each fuel rod 22 can be irradiated under favorable temperature conditions.

[0061] The inner diameter of the inner target tube 21 is not a fixed value, but varies along a specific direction (defined as the first direction). This variation is not an arbitrary, continuous change, but rather a step-like change.

[0062] Specifically, the first direction can be any direction along the axial direction of the inner target tube 21. When observing the inner target tube 21 along the first direction, it will be observed that the inner diameter of the inner target tube 21 will suddenly increase or decrease, forming a step-like shape. For example, in a certain section of the inner target tube 21, the inner diameter may be a small fixed value, and then after passing through a transition region, the inner diameter suddenly increases to another fixed value, and then may maintain this larger inner diameter for a period of time, after which the inner diameter will decrease again. This step-like change in inner diameter can be regular or determined according to the specific design requirements of the irradiation device; this embodiment does not limit this.

[0063] In the above embodiments, see Figure 2 As shown, at least two air inlets 241 are provided, and each air inlet 241 is connected to an air inlet pipe, and different air inlets are used to pass through different types of gases.

[0064] In this embodiment, at least two air inlets 241 are provided, and each air inlet 241 is connected to an air inlet pipe for introducing different types of gases. This allows for the introduction of various gases into the fuel rod assembly 2. During nuclear irradiation, different gas environments may be required depending on the experimental purpose or the performance requirements of the fuel rod 22. For example, sometimes helium is needed for heat dissipation because helium has good thermal conductivity; sometimes inert gases such as neon may be needed to adjust the gas pressure inside the inner target tube 21 or change the neutron energy spectrum. Multiple air inlets 241 and multiple air inlet pipes allow for flexible selection and control of the introduced gas types. Simultaneously, specific gas environments can be precisely created. Different fuel rods 22 may have different requirements for gas composition during irradiation. This implementation can provide suitable gases based on the location of the fuel rod 22 (e.g., fuel rods 22 in different diameter regions of the inner target tube 21) or the type of fuel rod 22 (e.g., novel fuel rods 22 and conventional fuel rods 22). For example, for some fuel rods 22 that are more sensitive to oxidation, an inert gas can be continuously introduced through one intake pipe to prevent oxidation, while a small amount of gas for auxiliary heat dissipation can be introduced through another intake pipe, thereby precisely meeting the special gas environment requirements of the fuel rod 22.

[0065] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 3 As shown, the neutron screen assembly 3 includes: an inner sleeve 31, an outer sleeve 32, and multiple neutron screens 33. The inner sleeve 31 is disposed inside the outer sleeve 32, and the two ends of the outer sleeve 32 and the inner sleeve 31 are sealed together by cover plates 34. The outer side of the inner sleeve 31, the inner side of the outer sleeve 32, and the two cover plates 34 form a sealed cavity. The multiple neutron screens 33 are arranged sequentially in the sealed cavity along the axial direction.

[0066] In this embodiment, the neutron screen assembly 3 effectively shields and filters neutrons. The neutron energy spectrum in a thermal spectroscopy research reactor differs from that in a fast reactor. The neutron screen 33 can block some unwanted neutrons, allowing neutrons with energy spectrum characteristics more consistent with a fast reactor to pass through, thereby creating a locally approximate fast reactor neutron energy spectrum environment for the fuel rod assembly 2 internally. Furthermore, the sealed cavity, composed of the outer surface of the inner sleeve 31, the inner surface of the outer sleeve 32, and two cover plates 34, provides a stable installation environment for the neutron screen 33, preventing external factors from interfering with it and ensuring that its performance remains unaffected. Simultaneously, the sealed cavity also helps control the reflection and scattering paths of neutrons internally, reducing neutron leakage, improving neutron utilization efficiency, and further optimizing the neutron energy spectrum modulation effect.

[0067] The neutron screen component 3 can be a nested structure. Specifically, the inner sleeve 31 is located at the innermost layer, and the outer sleeve 32 wraps around the inner sleeve 31, forming a double-layer tube structure, while the multiple neutron screens 33 are placed in the space between these two layers of tubes.

[0068] The outer sleeve 32 and the inner sleeve 31 are sealed together at both ends by a cover plate 34. The cover plate 34 seals the openings at both ends, creating a relatively independent space between the inner sleeve 31 and the outer sleeve 32. This ensures the integrity of the internal structure and prevents external substances (such as dust and impurities) from entering the space between the inner sleeve 31 and the outer sleeve 32, while also preventing the leakage of internal gases or neutrons.

[0069] In this embodiment, multiple neutron screens 33 are sequentially arranged along the axial direction within the sealed cavity, which can be the length direction of the inner sleeve 31 and the outer sleeve 32. In this embodiment, the neutron screens 33 are divided into multiple segments and arranged sequentially, allowing for layered adjustment of neutrons according to different needs. Each segment of the neutron screen 33 can have different materials, thicknesses, or structures. Thus, during the propagation of neutrons from the outer layer to the internal space of the fuel rod assembly 2, different segments of the neutron screens 33 can sequentially absorb, scatter, or slow down the neutrons, thereby more precisely adjusting the neutron energy spectrum and flux, ultimately ensuring that the neutron energy spectrum reaching the fuel rod assembly 2 through the neutron screen assembly 3 better meets experimental requirements.

[0070] In the above embodiments, each sub-screen 33 is made of different materials and has a different thickness.

[0071] In this embodiment, each segment of the neutron screen 33 is made of a different material, enabling the neutron screen assembly 3 to perform multi-dimensional screening and adjustment of neutrons. Different materials have different interaction characteristics with neutrons. For example, some materials have a strong moderation effect on fast neutrons, reducing their energy to be closer to the neutron energy level in a fast reactor; while other materials may have a good absorption effect on neutrons in a specific energy range, reducing unwanted neutron components. By combining these materials with different neutron adjustment characteristics into multiple segments of neutron screen 33, the neutron energy spectrum passing through the neutron screen assembly 3 can be precisely adjusted according to design requirements, making it more consistent with the actual neutron energy spectrum in a fast reactor. Simultaneously, the different thicknesses of each segment of the neutron screen 33 further enhance the precision of neutron energy spectrum adjustment. Thicker neutron screens 33 can more effectively absorb or scatter neutrons, suitable for situations requiring a significant reduction in certain energy neutrons. Thinner neutron screens 33 can be used for fine-tuning the neutron energy spectrum or for moderately moderifying higher-energy neutrons. For example, for a neutron flux with high energy and high flux, its flux is first reduced by a thicker neutron screen 33 with absorption function, and then its energy is finely adjusted by a thinner neutron screen 33 made of moderation material. In this way, the neutron energy spectrum can be gradually shaped with high precision, so that the neutron environment in which the fuel rod assembly 2 is located is closer to the fast reactor environment.

[0072] The combination of neutron screens 33 made of different materials allows for the coordinated regulation of neutrons. For example, one section of the neutron screen 33 might be made of boron, which has a strong absorption capacity for thermal neutrons. When a stream of thermal neutrons passes through this section of the neutron screen 33, most of the thermal neutrons are absorbed. Then, the next section of the neutron screen 33 might be made of graphite, which is mainly used to moderate neutrons. In this way, by arranging the neutron screens 33 of different materials in sequence, unwanted neutron components can be absorbed first, and the remaining neutrons can be moderated, thereby precisely shaping a neutron energy spectrum that meets the requirements.

[0073] The thickness of each neutron screen 33 varies. Understandably, the thickness directly affects the neutron shielding effectiveness of the neutron screen 33. A thicker neutron screen 33 provides stronger shielding capabilities. For example, if the primary function of a neutron screen 33 is to absorb neutrons within a specific energy range, increasing its thickness allows more of these neutrons to be absorbed. Just as a thick wall blocks light more effectively than a thin wall, a thicker neutron-absorbing screen can more effectively reduce the number of unwanted neutrons. Simultaneously, different thicknesses are also used for fine-tuning the neutron energy spectrum and flux. Thinner neutron screens 33 cause relatively smaller changes to the neutron energy spectrum, making them suitable for situations requiring minor adjustments to the neutron energy spectrum. For example, after passing through a thicker screen primarily used for neutron absorption, only a small adjustment to the energy of the remaining neutrons may be needed; in this case, a thinner moderation neutron screen 33 can be effective.

[0074] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 1 and Figure 4 As shown, the drive assembly 4 includes a drive part 41, a transmission part 42, and a connecting part 43; the first end of the connecting part 43 is connected to the transmission part 42, the second end of the connecting part 43 is connected to the neutron screen assembly 3, the transmission part 42 is also connected to the drive part 41, and the drive part 41 is used to drive the transmission part 42 to move, so as to drive the neutron screen assembly 3 to rotate circumferentially and / or move axially through the connecting part 43.

[0075] In this embodiment, the drive unit 41 drives the neutron screen assembly 3 to rotate circumferentially via the transmission unit 42 and the connecting unit 43, thereby changing the angle at which neutrons enter the fuel rod assembly 2 and thus altering the neutron flux in a local area, optimizing the irradiation uniformity of each part of the fuel rod 22. Simultaneously, the drive unit 41, through the transmission unit 42 and the connecting unit 43, can also drive the neutron screen assembly 3 to move axially, changing the relative position of the fuel rod assembly 2 within the neutron screen assembly 3. This allows the fuel rod assembly 2 to be placed in different neutron environments, providing more suitable irradiation conditions for the fuel rod 22. Furthermore, axial movement can also be used to simulate the irradiation conditions of the fuel rod 22 at different locations in the fast reactor, increasing the diversity and practicality of irradiation experiments.

[0076] The connecting part 43 acts as a bridge, with its first end connected to the transmission part 42 and its second end connected to the neutron screen assembly 3. This transmits the motion of the transmission part 42 to the neutron screen assembly 3. The transmission part 42 is connected to the drive part 41, which serves as a power source. The power generated by the drive part 41 is transmitted through the transmission part 42 and the connecting part 43, ultimately acting on the neutron screen assembly 3. In practical applications, the connecting part 43 can be directly connected to the neutron screen assembly 3 to transmit the power from the transmission part 42 to the neutron screen assembly 3, enabling the neutron screen assembly 3 to rotate circumferentially and / or move axially.

[0077] The drive unit 41 is the power core of the entire drive assembly 4. Specifically, the drive unit 41 generates power to drive the transmission unit 42. This power can be mechanical force, such as the rotational force generated by an electric motor; or it can be other forms of force, such as hydraulic or pneumatic force. Understandably, the power output of the drive unit 41 is controlled according to experimental requirements, such as by setting parameters like its rotational speed, direction, or axial thrust through a control system.

[0078] The transmission unit 42 is primarily responsible for transmitting the power generated by the drive unit 41 to the connecting unit 43. The transmission unit 42 acts like an energy "conveyor belt," ensuring efficient power transfer from the drive unit 41 to the connecting unit 43, and may perform necessary conversions or adjustments during the transmission process. For example, if the drive unit 41 generates high-speed rotational power, while the connecting unit 43 requires lower speed but higher torque power to drive the neutron screen assembly 3, the transmission unit 42 can perform speed reduction and torque increase operations through gear sets or similar mechanisms. Furthermore, besides transmitting power, the transmission unit 42 may also perform motion conversion. For instance, if the drive unit 41 is a power source generating circumferential rotational motion, while the neutron screen assembly 3 requires axial linear motion, the transmission unit 42 can convert the rotational motion into linear motion through a screw-nut mechanism or a worm gear mechanism, thereby meeting the motion requirements of the neutron screen assembly 3.

[0079] In the above embodiments, see Figure 1 and Figure 4 As shown, the drive unit 41 includes a first drive unit 411, and the transmission unit 42 includes a first cylindrical gear 421, a second cylindrical gear 422, a guide rod 423, and a guide tube 424. The drive end of the first drive unit 411 is connected to the first cylindrical gear 421, the second cylindrical gear 422 meshes with the first cylindrical gear 421, and the guide rod 423 is connected to the second cylindrical gear 422. The first drive unit 411 is used to drive the first cylindrical gear 421 to rotate, and then drive the guide rod 423 to rotate around the axis of the second cylindrical gear 422 through the second cylindrical gear 422. At least a portion of the guide rod 423 is movably disposed in the guide tube 424, and the guide tube 424 is connected to the connecting part 43, thereby driving the connecting part 43 to rotate synchronously.

[0080] In this embodiment, the first drive unit 411 of the drive unit 41 drives the guide rod 423 to rotate via a cylindrical gear transmission. This cylindrical gear transmission method (with the first cylindrical gear 421 and the second cylindrical gear 422 meshing) has high transmission accuracy. The meshing between the gear teeth can accurately transmit power, ensuring the accuracy of the rotational motion.

[0081] The first drive unit 411 of the drive unit 41 is the power source for the circumferential rotation of the neutron screen assembly 3. The drive end of the first drive unit 411 is connected to the first cylindrical gear 421, meaning that the power generated by the first drive unit 411 can directly act on the first cylindrical gear 421, causing the first cylindrical gear 421 to rotate. For example, the first drive unit 411 may be a motor, and the output shaft of the motor is fixed to the first cylindrical gear 421 by means of a key connection or other means. When the motor starts, the rotation of the motor shaft will drive the first cylindrical gear 421 to rotate synchronously.

[0082] In this embodiment, the second cylindrical gear 422 meshes with the first cylindrical gear 421. When the first cylindrical gear 421 starts to rotate under the drive of the first drive unit 411, the second cylindrical gear 422 will rotate accordingly due to the interaction between the teeth of the gears. In this embodiment, the guide rod 423 is connected to the second cylindrical gear 422, and the number of teeth of the second cylindrical gear 422 is greater than the number of teeth of the first cylindrical gear 421. When the first drive unit 411 drives the first cylindrical gear 421 to rotate, the power is transmitted to the second cylindrical gear 422 through gear meshing. Since the second cylindrical gear 422 has more teeth, according to the gear transmission principle, a torque amplification effect will occur. This means that the torque output to the guide rod 423 increases during the transmission process. For loads that need to drive the neutron screen assembly 3, which may have a large moment of rotational inertia, a larger torque can ensure its stable rotation and overcome the resistance caused by factors such as friction, air resistance, and the weight of the assembly itself. At the same time, the gear ratio also makes the rotational speed of the second cylindrical gear 422 lower than that of the first cylindrical gear 421, which helps to achieve more precise angle control.

[0083] At least two guide rods 423 are provided, and the at least two guide rods 423 are evenly arranged along the circumferential direction of the second cylindrical gear 422. When the second cylindrical gear 422 rotates, the at least two guide rods 423 can rotate around the axis of the second cylindrical gear 422. In this embodiment, the guide rods 423 can be fixed to the side of the second cylindrical gear 422 near the neutron screen assembly 3 by welding or bolting, ensuring the synchronous movement of the guide rods 423 and the second cylindrical gear 422.

[0084] Each guide rod 423 is inserted into a corresponding guide tube 424, and the guide tube 424 is fixed relative to the connecting part 43. When the guide rod 423 rotates under the drive of the second cylindrical gear 422, it can drive the guide tube 424 to rotate around the axis of the second cylindrical gear 422.

[0085] In this configuration, the centerlines of the neutron screen assembly 3, the connecting part 43, and the second cylindrical gear 422 coincide. When the guide tube 424 rotates around the centerline of the second cylindrical gear 422, the connecting part 43 can drive the neutron screen assembly 3 to rotate circumferentially, thereby achieving precise control over the circumferential rotation angle of the neutron screen assembly 3.

[0086] Specifically, in this embodiment, the drive unit 41 is located on the side of the positioning flange 1 away from the neutron screen assembly 3, providing a stable foundation for the drive function while avoiding interference with the surrounding space of the neutron screen assembly 3. The connecting unit 43 is located on the side of the positioning flange 1 closer to the neutron screen assembly 3, allowing the connecting unit 43 to be easily connected to the neutron screen assembly 3, thereby effectively transmitting the power from the transmission unit 42 to the neutron screen assembly 3 and controlling its movement. In this structure, the transmission unit 42 is located between the drive unit 41 and the connecting unit 43, playing a crucial role in connecting the two. It should be noted that the transmission unit 42 spatially penetrates the positioning flange 1. More specifically, the guide rod 423 in the transmission section 42 passes through the opening in the middle of the positioning flange 1, ensuring the continuity and stability of the power transmission from the drive section 41 through the transmission section 42 to the connection section 43. This allows the entire power transmission path to be realized smoothly, providing reliable power support for the circumferential rotation and axial movement of the neutron screen assembly 3. This ensures the accuracy and effectiveness of the motion control of the neutron screen assembly 3 during the operation of the irradiation device, and further ensures that the irradiation experiment can be carried out under the expected conditions.

[0087] In the above embodiments, see Figure 1 and Figure 4 As shown, the drive unit 41 further includes a second drive unit 412, and the transmission unit 42 further includes a bevel gear set 425, a lead screw shaft 426, and a driven shaft 427. The drive end of the second drive unit 412 is connected to the input end of the bevel gear set 425, and the output end of the bevel gear set 425 is connected to the lead screw shaft 426. The lead screw shaft 426 is engaged with the driven shaft 427 through a pipe thread. The second drive unit 412 is used to drive the bevel gear set 425 to rotate, so that the lead screw shaft 426 drives the driven shaft 427 to move axially. The driven shaft 427 is connected to the connecting part 43 to drive the connecting part 43 to move axially.

[0088] In this embodiment, the second drive unit 412 drives the lead screw shaft 426 via a bevel gear set 425, which can change the direction of power transmission. In this structure, the bevel gear set 425 can convert the power output direction of the second drive unit 412 into a direction suitable for the circumferential rotation of the lead screw shaft 426, ensuring that the lead screw shaft 426 can rotate stably in the expected direction, providing precise power for the axial movement of the driven shaft 427.

[0089] The second drive unit 412 of the drive unit 41 provides the power source for the axial movement of the neutron screen assembly 3. The drive end of the second drive unit 412 is connected to the input end of the bevel gear set 425, meaning that the power generated by the second drive unit 412 can be directly transmitted to the bevel gear set 425. For example, the second drive unit 412 can be a motor, and the output shaft of the motor is fixed to the input shaft of the bevel gear set 425 through a coupling or key connection. When the motor starts and rotates, it will drive the input end of the bevel gear set 425 to rotate synchronously.

[0090] In this transmission unit 422, the bevel gear set 425 serves to change the direction of power transmission. Specifically, the bevel gear set 425 can convert the direction of power output from the second drive unit 412 (usually horizontal or other directions) into a direction suitable for the circumferential rotation of the lead screw shaft 426. It can be understood that the working principle of the bevel gear set 425 is based on the meshing between two bevel gears. When the input bevel gear rotates under the drive of the second drive unit 412, the meshing output bevel gear rotates in a different direction, thereby transmitting power to the lead screw shaft 426, enabling the lead screw shaft 426 to rotate in the desired circumferential direction.

[0091] The lead screw shaft 426 has threads on its outer surface, and the driven shaft 427 has matching internal threads (pipe threads). When the lead screw shaft 426 rotates under the drive of the bevel gear set 425, due to the helix angle of the threads and the friction between the threads, the rotational motion of the lead screw shaft 426 is converted into the axial movement of the driven shaft 427, thereby driving the driven shaft 427 to move forward or backward along the axial direction of the lead screw shaft 426.

[0092] The driven shaft 427 can be connected to the connecting part 43 by welding, bolting, or spline connection, so that the axial movement of the driven shaft 427 can be transmitted to the connecting part 43. It is understood that as a component directly connected to the neutron screen assembly 3, changes in the motion state of the connecting part 43 will directly affect the position of the neutron screen assembly 3. In practical applications, when the second drive unit 412 drives the bevel gear set 425 to rotate, thereby causing the lead screw shaft 426 to drive the driven shaft 427 to move axially, the connecting part 43 will move axially synchronously under the drive of the driven shaft 427. This achieves control over the axial position of the neutron screen assembly 3, enabling precise adjustment of the axial position of the neutron screen assembly 3 relative to the fuel rod assembly 2 in the irradiation device. This changes the neutron energy spectrum and flux distribution around the fuel rod 22, meeting different irradiation experimental requirements, such as simulating the irradiation conditions of the fuel rod 22 at different axial positions or optimizing the irradiation uniformity of different parts of the fuel rod 22.

[0093] Specifically, in this embodiment, the centerlines of the output end of the bevel gear set 425, the lead screw shaft 426, the driven shaft 427, and the connecting part 43 coincide, avoiding vibration or oscillation that may be caused by shaft center deviation. It should be noted that the aforementioned coincident centerlines are also the rotation centers of the guide rod 423 and the guide tube 424. In practical applications, the output end of the bevel gear set 425 is rotatably connected to the lead screw shaft 426 through an opening in the center of the positioning flange 1.

[0094] In the above embodiments, see Figure 1 As shown, the connecting part 43 includes a connecting flange 431 and a connecting pipe 432. The connecting flange 431 is used to fix the guide pipe 424, the driven shaft 427 and the connecting pipe 432. The end of the connecting pipe 432 away from the connecting flange 431 is connected to the neutron screen assembly 3.

[0095] In this embodiment, the connecting flange 431 securely connects the guide tube 424, the driven shaft 427, and the connecting tube 432 together, so that when the guide tube 424 drives the connecting flange 431 to rotate circumferentially, the driven shaft 427 and the connecting tube 432 can move synchronously with it. This can effectively transmit the rotational force of the guide tube 424 to the connecting tube 432, thereby driving the neutron screen assembly 3 to rotate circumferentially. At the same time, when the driven shaft 427 moves axially, the connecting flange 431 can also ensure that the connecting tube 432 moves axially accordingly, realizing the effective transmission of the two motion modes.

[0096] Among them, the guide tube 424 and the driven shaft 427 can be fixed to the connecting flange 431 by means of bolt connection or interference fit; the connecting tube 432 may also be connected to the connecting flange 431 by means of welding, flange connection or groove connection.

[0097] Specifically, in practical applications, when the guide tube 424 rotates, since the guide tube 424 and the connecting flange 431 are fixedly connected, the rotational force of the guide tube 424 will be transmitted to the connecting flange 431. At the same time, the axial movement of the driven shaft 427 will also be transmitted through the connecting flange 431.

[0098] The end of the connecting pipe 432 away from the connecting flange 431 is connected to the neutron screen assembly 3, making the connecting pipe 432 a bridge between the connecting flange 431 and the neutron screen assembly 3, and transmitting the movement of the connecting flange 431 to the neutron screen assembly 3.

[0099] Specifically, in terms of circumferential rotation, when the connecting flange 431 rotates under the drive of the guide tube 424, the connecting tube 432 rotates together with the connecting flange 431, thereby transmitting the rotational motion to the neutron screen assembly 3. In terms of axial movement, when the connecting flange 431 moves axially under the drive of the driven shaft 427, the connecting tube 432 also moves axially, thereby driving the neutron screen assembly 3 to perform axial displacement.

[0100] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0101] 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. An irradiation device, characterized in that, include: Positioning flange (1), said positioning flange (1) is installed on the top fixing structure of the research stack; Fuel rod assembly (2), which is fixed relative to the positioning flange (1); Neutron screen (33) assembly (3), the neutron screen assembly (3) is disposed outside the fuel rod assembly (2), the neutron screen assembly (3) is provided with an axial hollow channel inside, and the fuel rod assembly (2) is located inside the hollow channel; A drive assembly (4) is connected to the neutron screen assembly (3) and is used to drive the neutron screen assembly (3) to rotate circumferentially and / or move axially relative to the fuel rod assembly (2).

2. The irradiation apparatus according to claim 1, characterized in that, The fuel rod assembly (2) includes: The inner target tube (21) and multiple fuel rods (22); The inner target tube (21) is provided with an upper cover (23) at one end near the positioning flange (1). The upper cover (23) has an air outlet (231) for connecting to an air outlet pipe. The inner target tube (21) is provided with a lower cover (24) at one end away from the positioning flange (1). The lower cover (24) has an air inlet (241) for connecting to an air inlet pipe. Multiple fuel rods (22) are disposed inside the inner target tube (21). Positioning blocks (25) are respectively provided at both ends of the multiple fuel rods (22), and connecting blocks (26) are provided between two adjacent fuel rods (22). A through hole is provided at the center of the positioning block (25) and the connecting block (26), and the through hole is used to allow gas to pass through.

3. The irradiation apparatus according to claim 2, characterized in that, The inner target tube (21) is a variable diameter tube, and the inner diameter of the inner target tube (21) changes in a stepped manner along the first direction.

4. The irradiation apparatus according to claim 2, characterized in that, At least two air inlets (241) are provided, and each air inlet (241) is connected to an air inlet pipe in a one-to-one correspondence, and different air inlets are used to pass through different types of gases.

5. The irradiation apparatus according to claim 1, characterized in that, The neutron screen component (3) includes: Inner sleeve (31), outer sleeve (32) and multi-segment neutron screen (33); The inner sleeve (31) is disposed inside the outer sleeve (32). The two ends of the outer sleeve (32) and the inner sleeve (31) are sealed together by cover plates (34). The outer side of the inner sleeve (31), the inner side of the outer sleeve (32) and the two cover plates (34) constitute a sealed cavity. Multiple neutron screens (33) are arranged sequentially along the axial direction in the sealed cavity.

6. The irradiation apparatus according to claim 5, characterized in that, The neutron screens (33) in each segment are made of different materials and have different thicknesses.

7. The irradiation apparatus according to claim 1, characterized in that, The driving component (4) includes: Drive unit (41), transmission unit (42), and connecting unit (43); The first end of the connecting part (43) is connected to the transmission part (42), and the second end of the connecting part (43) is connected to the neutron screen assembly (3). The transmission part (42) is also connected to the driving part (41). The driving part (41) is used to drive the transmission part (42) to move so as to drive the neutron screen assembly (3) to rotate circumferentially and / or move axially through the connecting part (43).

8. The irradiation apparatus according to claim 7, characterized in that, The drive unit (41) includes a first drive unit (411), and the transmission unit (42) includes a first cylindrical gear (421), a second cylindrical gear (422), a guide rod (423), and a guide tube (424); The driving end of the first driving unit (411) is connected to the first cylindrical gear (421), the second cylindrical gear (422) meshes with the first cylindrical gear (421), and the guide rod (423) is connected to the second cylindrical gear (422). The first driving unit (411) is used to drive the first cylindrical gear (421) to rotate, and then drive the guide rod (423) to rotate around the axis of the second cylindrical gear (422) through the second cylindrical gear (422); At least a portion of the guide rod (423) is movably disposed within the guide tube (424), which is connected to the connecting part (43), thereby driving the connecting part (43) to rotate synchronously.

9. The irradiation apparatus according to claim 8, characterized in that, The drive unit (41) further includes a second drive unit (412), and the transmission unit (42) further includes a bevel gear set (425), a lead screw shaft (426), and a driven shaft (427); The driving end of the second driving unit (412) is connected to the input end of the bevel gear set (425), and the output end of the bevel gear set (425) is connected to the lead screw shaft (426). The lead screw shaft (426) is engaged with the driven shaft (427) through a pipe thread. The second drive unit (412) is used to drive the bevel gear set (425) to rotate, so that the lead screw shaft (426) drives the driven shaft (427) to move axially. The driven shaft (427) is connected to the connecting part (43) to drive the connecting part (43) to move axially.

10. The irradiation apparatus according to claim 9, characterized in that, The connecting part (43) includes a connecting flange (431) and a connecting pipe (432). The connecting flange (431) is used to fix the guide pipe (424), the driven shaft (427) and the connecting pipe (432). The end of the connecting pipe (432) away from the connecting flange (431) is connected to the neutron screen assembly (3).

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