Reactor fuel irradiation device

Abstract

The present application provides a fuel irradiation device with a reactor, comprising a device section and a test section, wherein the device section is provided with a coolant delivery pipe, and the test section comprises an upper joint, an outer sleeve and a lower joint connected in sequence along a first direction; the upper joint extends into the coolant delivery pipe and is sealed with a gap in the coolant delivery pipe to form an annular gap, and the upper joint is circumferentially provided with a first spacer layer connected to the annular gap, and when conducting a test, the coolant in the annular gap can enter the first spacer layer and be in a static stagnant state, thereby forming a first thermal insulation structure; the outer sleeve is circumferentially provided with a second spacer layer, and one end of the second spacer layer is open, so that the coolant outside the outer sleeve can enter the second spacer layer and be in a static stagnant state, thereby forming a second thermal insulation structure; the lower joint is circumferentially provided with a third spacer layer, and one end of the third spacer layer is open, so that the coolant outside the lower joint can enter the third spacer layer and be in a static stagnant state, thereby forming a third thermal insulation structure.

Description

Technical Field

[0001] The present application belongs to the field of research reactor irradiation technology, and specifically relates to a reactor fuel irradiation device. Background Art

[0002] Fuel performance has a direct impact on reactor safety and economics, and conducting fuel irradiation tests is a critical step in fuel development and design. In these tests, the fuel's measured power is calculated by measuring the coolant inlet and outlet temperature, flow rate, and pressure differential at the test fuel section of the fuel irradiation device. However, since the test fuel section of the fuel irradiation device is typically scaled-down fuel, its in-pile heating value is lower than that of the prototype, resulting in a smaller temperature difference between the coolant inlet and outlet of the irradiation device. In this case, measurement errors in the temperature measuring element can significantly affect the test results, resulting in poor power measurement accuracy. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present application is to provide a fuel irradiation device with a stack, which can increase the temperature rise of the coolant after passing through the test fuel section, thereby reducing the impact of measurement errors on the test results and improving the accuracy of power measurement.

[0004] In order to solve the above problems, the present application provides a fuel irradiation device for a reactor, comprising a device section and a test section, wherein the device section is provided with a coolant delivery pipe, and the test section comprises an upper joint, an outer sleeve, and a lower joint connected in sequence along a first direction;

[0005] The upper joint extends into the coolant delivery pipe and is gap-sealed with the coolant delivery pipe to form an annular gap. The upper joint is circumferentially provided with a first spacer layer communicating with the annular gap. During a test, the coolant in the annular gap can enter the first spacer layer and remain in a stagnant state, thereby forming a first thermal insulation structure.

[0006] The outer sleeve is provided with a second spacer layer along the circumference, and one end of the second spacer layer is open, so that the coolant outside the outer sleeve can enter the second spacer layer and be in the static stagnant state, thereby forming a second thermal insulation structure;

[0007] The lower joint is circumferentially provided with a third spacer layer, one end of which is open, so that the coolant outside the lower joint can enter the third spacer layer and be in the static stagnant state, thereby forming a third thermal insulation structure.

[0008] Optionally, a plurality of annular sealing teeth are provided on the outer peripheral surface of the upper joint at a position relative to the annular gap, the plurality of sealing teeth are arranged at intervals along the axial direction, and the tooth tops of the sealing teeth are in gap sealing fit with the inner wall of the coolant delivery pipe.

[0009] Optionally, a test fuel segment, a resistance plug and a mixer are sequentially arranged in the outer sleeve along the first direction, the test fuel segment is used to carry fuel core blocks, the fuel core blocks are used to exchange heat with the coolant passing through the test fuel segment, the resistance plug is used to apply resistance to the coolant passing through the test fuel segment, and the mixer is used to stir the coolant passing through the resistance plug.

[0010] Optionally, the test fuel segment includes a clamp block, which is a hollow structure to form a positioning cavity for accommodating the fuel core block. The positioning cavity has at least two limiting parts to position at least two of the fuel core blocks. The at least two fuel core blocks are used to divide the limiting cavity into at least three rectangular flow channels, and the at least three rectangular flow channels are used to pass the coolant.

[0011] Optionally, at least three of the rectangular flow channels include an inner flow channel located between two of the fuel core blocks and outer flow channels distributed on both sides of the inner flow channel, and the passage area of ​​the inner flow channel is larger than the passage area of ​​the outer flow channel.

[0012] Optionally, the test fuel section further includes a clamping plate, the clamping block is connected to the clamping plate, the clamping plate protrudes from the outer wall of the clamping block and cooperates with the inner wall of the outer sleeve to form an annular flow channel between the clamping block and the outer sleeve, and the annular flow channel is also used to pass the coolant.

[0013] Optionally, the resistance plug includes a blocking body axially arranged in the outer sleeve, a plurality of upper support columns are circumferentially spaced apart at one end of the blocking body, and a plurality of lower support columns are circumferentially spaced apart at the other end of the blocking body, and portions of the upper support columns and the lower support columns radially protrude from the outer wall of the blocking body and cooperate with the inner wall of the outer sleeve to form a resistance flow channel between the blocking body and the outer sleeve.

[0014] Optionally, a plurality of annular blocking teeth are provided on the outer peripheral surface of the blocking body at a position relative to the resistance flow channel, and the plurality of blocking teeth are arranged at equal intervals along the axial direction. The sum of the spacing between two adjacent blocking teeth and the tooth width of a single blocking tooth is 10 mm, the tooth width of a single blocking tooth is 2 mm to 5 mm, and the tooth depth of a single blocking tooth is less than or equal to 3 mm.

[0015] Optionally, the mixer is a disc-shaped structure, the outer wall of the mixer cooperates with the outer sleeve, and the mixer is evenly distributed with several guide holes passing through the mixer. The center lines of several guide holes intersect, and the intersection is located on the first direction side of the mixer.

[0016] Optionally, an inclination angle of a center line of the guide hole relative to a central axis of the flow mixer is less than or equal to 10 degrees.

[0017] Beneficial effects

[0018] The stack-mounted fuel irradiation device provided in the embodiments of the present invention optimizes the heat transfer path by providing a first thermal insulation structure, a second thermal insulation structure, and a third thermal insulation structure, so that the coolant can fully absorb heat when flowing through the test fuel section, reducing the diffusion of heat to the surrounding unrelated areas, and achieving a greater increase in the temperature of the coolant after passing through the test fuel section, thereby reducing the impact of measurement errors on the test results and improving the accuracy of the measured power. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of a reactor fuel irradiation device according to an optional embodiment of the present application;

[0020] Figure 2 This is a schematic structural diagram of an upper joint of an optional embodiment of the present application;

[0021] Figure 3 This is a schematic structural diagram of an outer sleeve of an optional embodiment of the present application;

[0022] Figure 4 This is a schematic structural diagram of a lower joint of an optional embodiment of the present application;

[0023] Figure 5 A cross-sectional view of a test fuel section according to an alternative embodiment of the present application;

[0024] Figure 6 This is a schematic structural diagram of a resistance plug according to an optional embodiment of the present application;

[0025] Figure 7 This is a schematic structural diagram of a blocking body according to an optional embodiment of the present application.

[0026] The reference numerals indicate:

[0027] 1. Upper joint; 11. First spacer; 12. Sealing tooth; 13. Positioning pin; 2. Outer sleeve; 21. Second spacer; 22. Exhaust port; 3. Lower joint; 31. Third spacer; 32. Exhaust hole; 33. Leakage trough; 4. Upper spacer; 5. Test fuel section; 51. Fuel core; 52. Clamp; 53. Clamp; 54. Inner flow channel; 55. Outer flow channel; 56. Annular flow channel; 6. Resistance plug; 61. Blocking body; 62. Upper support column; 63. Lower support column; 64. Flow blocking tooth; 7. Mixer; 71. Guide hole; 8. Coolant delivery pipe; 9. Annular gap; 10. Thermocouple measuring point. DETAILED DESCRIPTION

[0028] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] 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 the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0030] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0031] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0032] See also Figures 1 to 7As shown, according to an embodiment of the present application, a fuel irradiation device is provided, including a device section and a test section. The device section is provided with a coolant delivery pipe 8, and the test section includes an upper joint 1, an outer sleeve 2 and a lower joint 3 connected in sequence along a first direction; the upper joint 1 extends into the coolant delivery pipe 8 and is gap-sealed with the coolant delivery pipe 8 to form an annular gap 9. The upper joint 1 is circumferentially provided with a first spacer layer 11 communicating with the annular gap 9. During a test, the coolant in the annular gap 9 can enter the first spacer layer 11 and be in a static stagnant state, thereby forming a first thermal insulation structure; the outer sleeve 2 is circumferentially provided with a second spacer layer 21, one end of the second spacer layer 21 is open, so that the coolant outside the outer sleeve 2 can enter the second spacer layer 21 and be in a static stagnant state, thereby forming a second thermal insulation structure; the lower joint 3 is circumferentially provided with a third spacer layer 31, one end of the third spacer layer 31 is open, so that the coolant outside the lower joint 3 can enter the third spacer layer 31 and be in a static stagnant state, thereby forming a third thermal insulation structure.

[0033] The provision of a first thermal insulation structure prevents heat from above the test fuel segment 5 from being transferred to other locations, such as the coolant delivery pipe 8. This reduces heat loss above the test fuel segment 5 and allows more heat to be retained in the coolant's flow path, thereby helping to increase the temperature rise of the coolant after it passes through the test fuel segment 5. The provision of a second thermal insulation structure prevents heat from being lost to the environment outside the outer casing 2, allowing more heat generated by the test fuel segment 5 to be absorbed by the coolant, improving the coolant's efficiency in absorbing heat and, in turn, increasing the temperature rise of the coolant after it passes through the test fuel segment 5. The provision of a third thermal insulation structure prevents heat loss below the test fuel segment 5, ensuring that the heat generated by the test fuel segment 5 is primarily carried away by the coolant. This increases the amount of heat absorbed by the coolant and ensures a significant temperature rise of the coolant after it passes through the test fuel segment 5. Furthermore, by setting up the first insulation structure, the second insulation structure and the third insulation structure, the heat transfer path is optimized, so that the coolant can fully absorb heat when flowing through the test fuel segment 5, reducing the diffusion of heat to the surrounding unrelated areas, and achieving a greater increase in the temperature of the coolant after passing through the test fuel segment 5, thereby reducing the impact of measurement errors on the test results and improving the accuracy of the measured power.

[0034] The coolant may be water, liquid metal, etc., which is not limited in this application. In this embodiment, the stacked fuel irradiation device is used for a water-cooled research reactor, and water is used as the coolant for illustration.

[0035] Specifically, the in-core fuel irradiation device includes a device section and a test section. 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 part of the test section is inserted into the lower grid partition of the core, and the test fuel section 5 in the test section is located in the active area of ​​the core.

[0036] The lower portion of the device section and the test section are both immersed in research reactor cooling water. Specifically, cooling water first flows into the device through an inlet located on the side of the lower portion. It then flows into the test section, where it performs a cooling function. After completing its cooling task, the water finally flows out. Throughout this process, the cooling water continuously circulates, ensuring stable temperature operation of the device and providing reliable cooling for the smooth progress of the test.

[0037] The lower portion of the device section is provided with a coolant delivery pipe 8. During operation of this embodiment, the cooling water in the research reactor acts as a coolant, first reaching the lower portion of the device section and then entering the test section through the coolant delivery pipe 8.

[0038] Among them, the test section is composed of multiple parts, including an upper joint 1, an outer sleeve 2 and a lower joint 3 connected in sequence along the first direction. When the cooling water flows in the device, its path is to enter the test section through the coolant delivery pipe 8. First, the cooling water reaches the upper joint 1, and then flows from the upper joint 1 into the outer sleeve 2. In the outer sleeve 2, the cooling water performs heat exchange and other functions with the relevant components in the test fuel section 5. After completing the process in the outer sleeve 2, the cooling water then flows to the lower joint 3, and finally flows out of the test section through the lower joint 3, and continues to circulate in the cooling system of the entire device. It should be noted that the first direction can be the direction from the device section to the test section or the flow direction of the cooling water in the test section.

[0039] The upper joint 1 is circumferentially provided with a first spacer layer 11. This first spacer layer 11 is a central sandwich structure provided on the outer wall of the upper joint 1. During testing, the first spacer layer 11 automatically fills with cooling water. Once the cooling water fills the first spacer layer 11, since only one end of the first spacer layer 11 is open, the cooling water within the first spacer layer 11 remains relatively stagnant, forming a dead water insulation zone.

[0040] Specifically, the upper joint 1 can be inserted into the coolant delivery pipe 8. A clearance fit is adopted between the outer wall of the upper joint 1 and the inner wall of the coolant delivery pipe 8 to form an annular gap 9 between the outer wall of the upper joint 1 and the inner wall of the coolant delivery pipe 8. In the first spacer layer 11, an annular groove is radially opened at the position corresponding to the annular gap 9, and the annular groove faces the annular gap 9, so that the first spacer layer 11 can communicate with the annular gap 9. When the test is carried out, part of the cooling water inside the coolant delivery pipe 8 will flow into the outer sleeve 2 through the upper joint 1, and the other part will enter the annular gap 9. Since the first spacer layer 11 is connected to the annular gap 9 through the annular groove, the cooling water in the annular gap 9 can enter the first spacer layer 11 through the annular groove. When the cooling water in the annular gap 9 enters the first spacer layer 11 through the annular groove, since the first spacer layer 11 is only open at the annular groove, the cooling water cannot form an effective circulation flow in the first spacer layer 11 and can only be in a relatively static and stagnant state, thereby effectively preventing the heat above the test fuel section 5 in the test section from being transferred to other parts such as the coolant delivery pipe 8.

[0041] The outer surface of the upper connector 1 is provided with a positioning pin 13, which can be a bump protruding from the outer wall of the upper connector 1. When the upper connector 1 is inserted into the coolant delivery pipe 8, the positioning pin 13 can limit the movement range of the upper connector 1, ensuring that the upper connector 1 and the coolant delivery pipe 8 are accurately positioned during assembly and maintain a stable connection.

[0042] The test fuel section 5 is located inside the outer sleeve 2 .

[0043] The outer sleeve 2 is circumferentially provided with a second spacer layer 21, a central sandwich structure formed within the outer sleeve 2's wall. During testing, cooling water outside the outer sleeve 2 automatically enters the second spacer layer 21. Because the second spacer layer 21 is open at only one end, the cooling water entering the second spacer layer 21 cannot effectively circulate and remains relatively stagnant, forming another dead-water insulation zone.

[0044] Specifically, the second spacer layer 21 is open at the end closest to the upper connector 1 and closed at the end further away from the upper connector 1. In other words, the upper end of the second spacer layer 21 is open, while the lower end is closed. An annular exhaust port 22 is formed at the open end of the second spacer layer 21, facing in the opposite direction to the first direction. It should be noted that the cooling water flowing outside the outer sleeve 2 also flows in the opposite direction to the first direction.

[0045] When cooling water flows in the reverse direction outside the outer casing 2 (i.e., in the opposite direction to the first direction), the upper end of the second spacer layer 21 is open and the annular exhaust port 22 is also oriented in the opposite direction to the first direction. On the one hand, the cooling water can enter the second spacer layer 21 more smoothly. On the other hand, because the lower end of the second spacer layer 21 is closed, the cooling water in the second spacer layer 21 cannot form an effective circulation flow and can only remain relatively stagnant, thus forming a stable dead water insulation zone, effectively preventing heat from dissipating to the environment outside the outer casing 2. This allows more heat generated by the test fuel section 5 to be absorbed by the cooling water, improving the efficiency of the cooling water's heat absorption and increasing the temperature rise of the cooling water after passing through the test fuel section 5. On the other hand, the provision of the annular exhaust port 22 can discharge any gas that may be present in the second spacer layer 21 during the cooling water's entry process, ensuring that the second spacer layer 21 is fully filled with cooling water, thereby better performing its thermal insulation function, further optimizing the heat transfer performance of the entire fuel irradiation device, and providing reliable guarantees for the accurate conduct of the test.

[0046] Specifically, the cooling water outside the outer sleeve 2 is at a higher pressure than the gas inside the second spacer layer 21. When the cooling water enters the second spacer layer 21, the pressure differential causes the gas inside to be quickly expelled and discharged into the external environment through the annular exhaust port 22. This not only ensures that the second spacer layer 21 is quickly filled with cooling water, forming a stable dead water insulation zone, but also prevents gas accumulation in the second spacer layer 21, which could affect the insulation effect.

[0047] The lower joint 3 is circumferentially provided with a third spacer layer 31, a central sandwich structure formed on the outer wall of the lower joint 3. During testing, cooling water outside the lower joint 3 automatically enters the third spacer layer 31. Because the third spacer layer 31 is open at only one end, the cooling water entering the third spacer layer 31 cannot form an effective circulation flow and can only remain relatively stagnant, forming another dead water insulation zone.

[0048] Specifically, the third spacer layer 31 is open at one end away from the outer sleeve 2, and is formed with a water inlet, which faces the first direction. At the same time, the third spacer layer 31 is radially provided with an exhaust hole 32 at one end close to the outer sleeve 2. When the cooling water flows outside the lower joint 3, the flow direction of the cooling water is opposite to the first direction. During the test, when the cooling water flows in the reverse direction (i.e., flows in the opposite direction of the first direction) through the lower joint 3, since the water inlet of the third spacer layer 31 faces the first direction, under the action of pressure, the cooling water can smoothly enter the third spacer layer 31 from the water inlet. In the process of the cooling water entering the third spacer layer 31, the exhaust hole 32 opened at one end of the third spacer layer 31 close to the outer sleeve 2 can timely discharge the gas in the third spacer layer 31, ensuring that the third spacer layer 31 can be fully filled with cooling water to form an effective thermal insulation structure. This is beneficial for the cooling water to enter the third spacer layer 31 to play an insulating role, prevent the heat loss under the test fuel segment 5, ensure that the heat generated by the test fuel segment 5 is mainly taken away by the cooling water, increase the heat absorption of the cooling water, and provide a guarantee for the significant increase in the temperature of the cooling water after passing through the test fuel segment 5; it can also discharge the gas in time to avoid gas accumulation affecting the insulation effect, further optimize the heat transfer performance of the stack fuel irradiation device, and improve the accuracy of the test results.

[0049] The lower joint 3 is further provided with a drainage groove 33 along the circumferential direction. The drainage groove 33 can be a rectangular groove or an arc groove provided on the outer circumferential surface of the lower joint 3, and this application does not limit this.

[0050] Specifically, the discharge groove 33 is located on the outer peripheral surface of the lower joint 3 at a position relative to the lower grid partition of the core to ensure that the cooling water can flow smoothly through the discharge groove 33, and at the same time play a role in draining and reducing pressure, guiding the flow direction of the cooling water, etc. when necessary.

[0051] In some possible embodiments disclosed in this application, Figure 2 As shown, several annular sealing teeth 12 are provided on the outer circumferential surface of the upper joint 1 relative to the annular gap 9. These teeth 12 are spaced axially apart, and their tips form a gap-sealed fit with the inner wall of the coolant delivery pipe 8. This creates a multi-seal structure, increasing viscous resistance and effectively preventing cooling water leakage from the annular gap 9. This reduces the deviation between the actual flow rate and the designed flow rate, effectively ensuring the accuracy of the test results.

[0052] The annular gap 9 is a space formed by the upper connector 1 extending into the coolant delivery pipe 8 and being gap-sealedly connected to the coolant delivery pipe 8 .

[0053] Specifically, the length of the annular gap 9 is greater than 100 mm, thereby extending the leakage path and increasing the difficulty of leakage.

[0054] A plurality of sealing teeth 12 are arranged at intervals in the annular gap 9 along the central axis of the annular gap 9. When cooling water flows in the annular gap 9, the plurality of sealing teeth 12 can effectively prevent the cooling water from leaking out of the annular gap 9.

[0055] Specifically, as one embodiment, several sealing teeth 12 are arranged at equal intervals, so that each sealing tooth 12 bears relatively uniform sealing pressure, ensuring that the sealing effect of the entire annular gap 9 is relatively consistent; as another embodiment, several sealing teeth 12 are arranged at gradual intervals, which can adapt to the changes in pressure and flow rate of cooling water in the annular gap 9, so that the sealing effect is more stable within the entire annular gap 9.

[0056] In some possible embodiments disclosed in this application, Figure 1 As shown, a test fuel segment 5, a resistance plug 6 and a mixer 7 are sequentially arranged in the outer sleeve 2 along the first direction. The test fuel segment 5 is used to carry fuel pellets 51, and the fuel pellets 51 are used to exchange heat with the cooling water passing through the test fuel segment 5. The resistance plug 6 is used to apply resistance to the cooling water passing through the test fuel segment 5, and the mixer 7 is used to stir the cooling water passing through the resistance plug 6.

[0057] The first direction is the flow direction of the cooling water in the outer casing 2 .

[0058] Among them, a test fuel section 5 is provided in the outer sleeve 2. The test fuel section 5 provides a fixed position and space for the fuel pellets 51, so that the cooling water passing through the test fuel section 5 can fully contact the fuel pellets 51, efficiently absorb the heat released by the fuel pellets 51, thereby improving the heat exchange efficiency.

[0059] Among them, a resistance plug 6 is provided on the downstream side of the test fuel segment 5 along the flow direction. The resistance plug 6 can apply resistance to the cooling water passing through the test fuel segment 5, so that the flow rate of the cooling water in the test fuel segment 5 is reduced, the contact time between the cooling water and the fuel core block 51 is increased, the adequacy of heat exchange is improved, and the cooling water can absorb more heat.

[0060] Among them, a mixer 7 is provided on the downstream side of the resistance plug 6 along the flow direction. The mixer 7 can stir the cooling water passing through the resistance plug 6, so that the cooling water can be quickly mixed and evenly mixed after flowing out of the test fuel section 5, avoiding the situation where the local temperature is too high or too low, and improving the accuracy of the test results.

[0061] The outer casing 2 is also provided with an upper spacer 4, which is positioned upstream of the test fuel section 5 along the flow path. It should be noted that the provision of the upper spacer 4 not only protects the device from various forces due to the flow of cooling water, temperature fluctuations, and the external environment, thereby enhancing structural stability; it also blocks the path for heat to be conducted upward from the test fuel section 5, reducing heat loss, increasing the temperature rise of the cooling water after passing through the test fuel section 5, and improving the cooling water's efficiency in absorbing heat.

[0062] In some possible embodiments disclosed in this application, Figure 5 As shown, the test fuel segment 5 includes a clamp block 52, which is a hollow structure to form a positioning cavity for accommodating the fuel pellets 51. The positioning cavity has at least two limiting portions to position at least two fuel pellets 51. The at least two fuel pellets 51 are used to divide the limiting cavity into at least three rectangular flow channels, and the at least three rectangular flow channels are used to pass cooling water.

[0063] Among them, the clamp block 52 is axially arranged inside the outer sleeve 2. As an embodiment, the clamp block 52 is a split structure, and the clamp block 52 includes a first clamp body and a second clamp body. When installing the fuel pellet 51, the fuel pellet 51 can be placed on the first clamp body first, and then the second clamp body is connected to the first clamp body, so as to fix the fuel pellet 51 in the positioning cavity; as another embodiment, the clamp block 52 is an integral structure, and the clamp block 52 is made of one piece. When installing the fuel pellet 51, the fuel pellet 51 is placed in the positioning cavity of the clamp block 52, and it is ensured that the fuel pellet 51 is accurately in contact with the limiting part in the positioning cavity to achieve precise positioning. In this embodiment, the clamp block 52 is a split structure.

[0064] The positioning cavity may be a cylindrical cavity or an elongated cavity that passes through the clamping block 52 , and may be capable of placing the fuel pellets 51 and allowing cooling water to pass through. This application does not impose any limitation on this.

[0065] The limiting features are located on the sidewalls of the positioning cavity and specifically consist of two recesses. When a fuel pellet 51 is placed in the positioning cavity, portions of its surface come into contact with the two recesses. These recesses work together to limit the movement of the fuel pellet 51 within the cavity, ensuring that the fuel pellet 51 is accurately positioned in the intended location and preventing unnecessary displacement during operation of the fuel irradiation device.

[0066] In some specific examples, the fuel pellet 51 is cylindrical, and the two depressions on the side wall of the positioning cavity are two arc-shaped grooves, which fit the side surfaces of the fuel pellet 51 and restrict the horizontal movement of the fuel pellet 51 from different positions.

[0067] In other specific examples, the fuel pellet 51 is long and narrow, and the two depressions on the side wall of the positioning cavity are two rectangular grooves. The two rectangular grooves can fit tightly against the sides of the fuel pellet 51, limiting the fuel pellet 51 from multiple directions and effectively restricting the movement of the fuel pellet 51 in the positioning cavity.

[0068] Specifically, in this embodiment, the fuel pellet 51 is in the shape of an elongated strip, and the limiting portions are two rectangular grooves on the side wall of the positioning cavity.

[0069] At least two positioning members are provided within the positioning cavity of the clamp block 52. The two rectangular grooves in each positioning member can closely fit the sides of a long, rectangular fuel pellet 51, limiting the position of the fuel pellet 51 from multiple directions and ensuring the stability of the fuel pellet 51 within the positioning cavity. The at least two positioning members work together to position at least two fuel pellets 51, allowing them to be arranged in an orderly manner within the positioning cavity and preventing unnecessary displacement during operation of the fuel irradiation device. When cooling water flows through the positioning cavity, it fully contacts each fuel pellet 51, enabling efficient heat exchange.

[0070] Specifically, taking two retaining members as an example, two elongated fuel pellets 51 are positioned within the positioning cavity of the clamping block 52. Due to their elongated shape, the two fuel pellets 51 and the inner wall of the positioning cavity together define three rectangular flow channels. As the cooling water flows through these three rectangular flow channels, it can fully exchange heat with the fuel pellets 51.

[0071] In the above embodiment, the at least three rectangular flow channels include an inner flow channel 54 located between two fuel pellets 51 and outer flow channels 55 distributed on both sides of the inner flow channel 54 . The passage area of ​​the inner flow channel 54 is larger than that of the outer flow channel 55 .

[0072] Specifically, the inner flow channel 54 is located directly between the two fuel pellets 51. Its larger flow area means more cooling water can flow directly into this area. Since the cooling water's primary function is to absorb heat released by the fuel pellets 51, the larger flow area of ​​the inner flow channel 54 allows more cooling water to fully contact the opposing sides of the two fuel pellets 51. This allows the cooling water in the inner flow channel 54 to absorb more heat in the same amount of time, improving heat exchange efficiency. On the other hand, a larger flow area also affects the flow rate of the cooling water in the inner flow channel 54. According to the principles of fluid mechanics, for a constant flow rate, the larger the flow area, the lower the flow rate. Therefore, the flow rate of the cooling water in the inner flow channel 54 is relatively slow. This increases the contact time between the cooling water and the fuel pellets 51, allowing heat to be transferred more efficiently from the fuel pellets 51 to the cooling water. Despite their smaller flow area, the outer flow channels 55 also play an important role in the overall heat exchange process. Distributed on both sides of the inner flow channel 54, the outer flow channels 55 serve to divert the cooling water flow. After the cooling water flows into the positioning cavity, some of it enters the outer flow channel 55, thus preventing localized overheating or undercooling caused by the concentration of all the cooling water in the inner flow channel 54. The cooling water in the outer flow channel 55 cools the sides of the fuel pellets 51, and together with the inner flow channel 54, achieves all-around cooling of the fuel pellets 51.

[0073] In some possible embodiments disclosed in this application, Figure 1 and Figure 5 As shown, the test fuel section 5 also includes a clamping plate 53, and the clamping block 52 is connected to the clamping plate 53. The clamping plate 53 protrudes from the outer wall of the clamping block 52 and cooperates with the inner wall of the outer sleeve 2 to form an annular flow channel 56 between the clamping block 52 and the outer sleeve 2. The annular flow channel 56 is also used to pass cooling water.

[0074] Among them, taking the clamp block 52 as a split structure as an example, the clamp plate 53 is an annular structure, and at least two clamp plates 53 are provided. At least two clamp plates 53 are respectively mounted on both ends of the clamp block 52 to lock the first clamp body, the second clamp body and the fuel pellet 51, thereby ensuring that the fuel pellet 51 is firmly wrapped in the positioning cavity of the clamp block 52 to prevent the fuel pellet 51 from displacement.

[0075] Specifically, the clamping plate 53 is mounted on the clamping block 52 and is loosely fitted with the inner wall of the outer sleeve 2. Because the clamping plate 53 protrudes from the outer wall of the clamping block 52, a certain gap exists between the clamping block 52 and the inner wall of the outer sleeve 2, thereby forming an annular flow channel 56. This provides a new flow path for the cooling water, increasing the contact area between the cooling water and the test fuel segment 5. This allows the cooling water to flow not only in the rectangular flow channels defined by the fuel pellets 51 for heat exchange, but also in the annular flow channel 56, contacting the surfaces of the clamping block 52, clamping plate 53, and other components, thereby absorbing heat from these components and reducing heat loss to the environment outside the outer sleeve 2.

[0076] In some possible embodiments disclosed in this application, Figure 6 As shown, the resistance plug 6 includes a blocking body 61 axially arranged in the outer sleeve 2, a plurality of upper support columns 62 are circumferentially spaced apart at one end of the blocking body 61, and a plurality of lower support columns 63 are circumferentially spaced apart at the other end of the blocking body 61. Parts of the upper support columns 62 and the lower support columns 63 radially protrude from the outer wall of the blocking body 61 and cooperate with the inner wall of the outer sleeve 2 to form a resistance flow channel between the blocking body 61 and the outer sleeve 2.

[0077] The provision of upper and lower support columns 62, 63 secures the blocking body 61 within the outer sleeve 2, providing support and preventing displacement or deformation under the impact of the cooling water. By occupying space within the outer sleeve 2, the blocking body 61 exerts resistance on the cooling water flowing out of the test fuel section 5, reducing the cooling water's velocity as it flows through the test fuel section 5. This prolongs the cooling water's contact time with the fuel pellets 51, allowing it more time to fully absorb the heat released by the fuel pellets 51 and thereby improving heat exchange efficiency.

[0078] In some specific examples, the blocking member 61 is a cylindrical structure, specifically a smooth cylindrical body. It mates closely with the upper support column 62 and the lower support column 63, allowing it to be stably positioned within the outer sleeve 2 and provide reliable resistance to the flow of cooling water. The cylindrical blocking member 61 has a sufficient axial length to fully occupy the space within the outer sleeve 2, ensuring that the cooling water encounters effective resistance as it flows through, thereby reducing the flow rate and increasing the heat exchange time.

[0079] In other specific examples, the blocking body 61 is barrel-shaped, similar to an open barrel. The barrel-shaped blocking body 61 opens toward the test fuel section 5, thereby forming a mixing chamber. When the cooling water enters the mixing chamber and contacts the bottom of the barrel, it generates an upward backflow effect, thereby agitating the cooling water and improving the measurement accuracy of the average cooling water outlet temperature of the test section.

[0080] There may be three upper support columns 62 and three lower support columns 63 , and the three upper support columns 62 and the three lower support columns 63 are evenly arranged along the circumferential direction of the blocking body 61 .

[0081] Specifically, the upper support column 62 and the lower support column 63 both extend in the radial direction, and portions of the upper support column 62 and the lower support column 63 both protrude radially from the outer wall of the blocking body 61 and cooperate with the inner wall of the outer sleeve 2, so that there is a certain gap between the outer wall of the blocking body 61 and the inner wall of the outer sleeve 2, thereby forming a resistance flow channel.

[0082] In the above embodiment, a plurality of annular blocking teeth 64 are provided on the outer peripheral surface of the blocking body 61 at a position relative to the resistance flow channel. The plurality of blocking teeth 64 are arranged at equal intervals along the axial direction. The sum of the spacing between two adjacent blocking teeth 64 and the tooth width of a single blocking tooth 64 is 10 mm. The tooth width of a single blocking tooth 64 is 2 mm to 5 mm, and the tooth depth of a single blocking tooth 64 is less than or equal to 3 mm.

[0083] The provision of the blocking teeth 64 in the resistance flow channel further increases the flow resistance to the cooling water. As the cooling water flows through the resistance flow channel, it not only has to overcome the resistance created by the blocking body 61 but also has to flow around the blocking teeth 64. This multiple resistance effect further reduces the flow rate of the cooling water, thereby increasing the contact time between the cooling water and the fuel pellets 51 and the blocking body 61 itself, thereby improving heat exchange efficiency.

[0084] The number of the baffle teeth 64 can be three, four or five, etc., which is not limited in this application.

[0085] The flow blocking teeth 64 are generally annular in shape and are arranged perpendicular to the outer peripheral surface of the blocking body 61 to form a stable resistance effect in the resistance flow channel.

[0086] Specifically, in this embodiment, the spacing between two adjacent blocking teeth 64 is preferably 7 mm, the tooth width of a single blocking tooth 64 is preferably 3 mm, and the tooth depth of a single blocking tooth 64 is preferably 2.7 mm.

[0087] In some possible embodiments disclosed in this application, Figure 7 As shown, the mixer 7 is a disc-shaped structure, the outer wall of the mixer 7 cooperates with the outer sleeve 2, and a number of guide holes 71 are evenly distributed on the mixer 7 and pass through the mixer 7. The center lines of the several guide holes 71 intersect, and the intersection is located on the first direction side of the mixer 7.

[0088] The flow mixer 7 changes the direction of the cooling water flow, promoting mixing of cooling water from different areas and improving the uniformity of heat exchange. Furthermore, the uniformly mixed cooling water ensures that the water temperature at the cooling water outlet of the test section more accurately reflects the effectiveness of the entire heat exchange process. This avoids measurement errors caused by local temperature differences, thereby improving the accuracy of the test results.

[0089] Among them, the outer diameter of the mixer 7 is adapted to the inner diameter of the outer sleeve 2, which can achieve a tight fit or a clearance fit, preventing the cooling water from flowing directly through the gap between the mixer 7 and the outer sleeve 2 without being stirred, thereby ensuring that the mixer 7 effectively treats the cooling water.

[0090] Among them, a plurality of guide holes 71 are evenly distributed on the plane of the flow mixer 7, so that the cooling water can enter the guide holes 71 from different positions, thereby achieving a more uniform stirring effect.

[0091] The guide hole 71 penetrates the flow mixer 7 so that the cooling water can flow from one side of the flow mixer 7 to the other side through the guide hole 71. When the cooling water passes through the guide hole 71, its flow direction will change due to the special arrangement of the guide hole 71.

[0092] Specifically, the centerlines of several guide holes 71 intersect, with the intersection located on the first direction side of the mixer 7. The first direction is the flow direction of the cooling water in the outer casing 2. This causes the cooling water flowing out of different guide holes 71 to converge near the intersection, resulting in a strong mixing effect. After passing through the resistance plug 6, the cooling water's flow rate and temperature may be uneven. Through the guidance and convergence of the guide holes 71, the cooling water can be quickly and evenly mixed, avoiding localized over-temperature conditions. This improves the uniformity and stability of heat exchange, thereby enhancing the performance of the entire in-combustion fuel irradiation device and the accuracy of the test results.

[0093] It should be noted that a thermocouple measuring point 10 is provided on the first direction side of the flow mixer 7 , and the thermocouple measuring point 10 is located inside the lower joint 3 .

[0094] In the above embodiment, the inclination angle of the center line of the guide hole 71 relative to the central axis of the mixer 7 is less than or equal to 10 degrees. In this way, it can be ensured that the change in the flow direction of the cooling water is relatively gentle when passing through the guide hole 71. This can avoid excessive turbulence of the water flow due to an excessively large inclination angle, reduce the instability of the water flow, and enable the cooling water to mix and flow in a relatively stable state. For example, the inclination angle of the center line of the guide hole 71 relative to the central axis of the mixer 7 is 2 degrees, or 4 degrees, or 6 degrees, or 8 degrees, or 10 degrees. It can be understood that the inclination angle of the center line of the guide hole 71 relative to the central axis of the mixer 7 can also be other values ​​other than the above values, as long as the inclination angle of the center line of the guide hole 71 relative to the central axis of the mixer 7 is less than or equal to 10 degrees.

[0095] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0096] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application. The above are merely preferred embodiments of the present application. It should be noted that those skilled in the art may make various improvements and variations without departing from the technical principles of the present application, and such improvements and variations shall also be considered within the scope of protection of the present application.

Claims

1. A fuel irradiation device, characterized in that: It comprises a device section and a test section, wherein the device section is provided with a coolant delivery pipe (8), and the test section comprises an upper joint (1), an outer sleeve (2), and a lower joint (3) connected in sequence along a first direction; The upper joint (1) extends into the coolant delivery pipe (8) and is gap-sealed with the coolant delivery pipe (8) to form an annular gap (9). The upper joint (1) is provided with a first spacer layer (11) in the circumferential direction and connected to the annular gap (9). When the test is carried out, the coolant in the annular gap (9) can enter the first spacer layer (11) and be in a static stagnant state, thereby forming a first thermal insulation structure. The outer sleeve (2) is provided with a second spacer layer (21) along the circumference, and one end of the second spacer layer (21) is open, so that the coolant outside the outer sleeve (2) can enter the second spacer layer (21) and be in the static stagnant state, thereby forming a second thermal insulation structure; The lower joint (3) is provided with a third spacer layer (31) along the circumference, and one end of the third spacer layer (31) is open, so that the coolant outside the lower joint (3) can enter the third spacer layer (31) and be in the static stagnant state, thereby forming a third thermal insulation structure.

2. The stacked fuel irradiation device according to claim 1, characterized in that: A plurality of annular sealing teeth (12) are provided on the outer peripheral surface of the upper joint (1) at a position relative to the annular gap (9), the plurality of sealing teeth (12) are arranged at intervals along the axial direction, and the tooth tops of the sealing teeth (12) are in gap sealing fit with the inner wall of the coolant delivery pipe (8).

3. The reactor-mounted fuel irradiation device according to claim 1, characterized in that: A test fuel section (5), a resistance plug (6) and a mixer (7) are sequentially arranged in the outer sleeve (2) along the first direction. The test fuel section (5) is used to carry fuel pellets (51), and the fuel pellets (51) are used to exchange heat with the coolant passing through the test fuel section (5). The resistance plug (6) is used to apply resistance to the coolant passing through the test fuel section (5), and the mixer (7) is used to stir the coolant passing through the resistance plug (6).

4. The reactor-mounted fuel irradiation device according to claim 3, characterized in that: The test fuel section (5) includes a clamping block (52), the clamping block (52) is a hollow structure to form a positioning cavity for accommodating the fuel pellets (51), the positioning cavity has at least two limiting parts to position at least two fuel pellets (51), and the at least two fuel pellets (51) are used to divide the positioning cavity into at least three rectangular flow channels, and the at least three rectangular flow channels are used to pass the coolant.

5. The stacked fuel irradiation device according to claim 4, characterized in that: At least three of the rectangular flow channels include an inner flow channel (54) located between two of the fuel core blocks (51) and outer flow channels (55) distributed on both sides of the inner flow channel (54), and the passage area of ​​the inner flow channel (54) is larger than the passage area of ​​the outer flow channel (55).

6. The stack-mounted fuel irradiation device according to claim 4, characterized in that: The test fuel section (5) further comprises a clamping plate (53), the clamping block (52) being connected to the clamping plate (53), the clamping plate (53) protruding from the outer wall of the clamping block (52) and cooperating with the inner wall of the outer sleeve (2) so as to form an annular flow channel (56) between the clamping block (52) and the outer sleeve (2), and the annular flow channel (56) is also used for passing the coolant.

7. The reactor-mounted fuel irradiation device according to claim 3, characterized in that: The resistance plug (6) comprises a blocking body (61) axially arranged in the outer sleeve (2), one end of the blocking body (61) is provided with a plurality of upper support columns (62) at intervals along the circumferential direction, and the other end of the blocking body (61) is provided with a plurality of lower support columns (63) at intervals along the circumferential direction, and both the upper support columns (62) and the lower support columns (63) partially protrude from the outer wall of the blocking body (61) in the radial direction and cooperate with the inner wall of the outer sleeve (2) to form a resistance flow channel between the blocking body (61) and the outer sleeve (2).

8. The stack-mounted fuel irradiation device according to claim 7, characterized in that: A plurality of annular flow-blocking teeth (64) are provided on the outer peripheral surface of the blocking body (61) at a position relative to the resistance flow channel. The plurality of flow-blocking teeth (64) are arranged at equal intervals along the axial direction. The sum of the spacing between two adjacent flow-blocking teeth (64) and the tooth width of a single flow-blocking tooth (64) is 10 mm. The tooth width of a single flow-blocking tooth (64) is 2 mm to 5 mm, and the tooth depth of a single flow-blocking tooth (64) is less than or equal to 3 mm.

9. The reactor-mounted fuel irradiation device according to claim 3, characterized in that: The mixer (7) is a disc-shaped structure. The outer wall of the mixer (7) cooperates with the outer sleeve (2). The mixer (7) is evenly distributed with a plurality of guide holes (71) passing through the mixer (7). The center lines of the plurality of guide holes (71) intersect, and the intersection point is located on the first direction side of the mixer (7).

10. The reactor-mounted fuel irradiation device according to claim 9, characterized in that: The inclination angle of the center line of the guide hole (71) relative to the center axis of the flow mixer (7) is less than or equal to 10 degrees.

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