Dispersion type fuel element surface foaming simulation measurement system and method

Abstract

The invention relates to the technical field of reactor thermal hydraulic power and safety, in particular to a dispersion type fuel element surface foaming simulation measurement system and method. The measuring system comprises a heated plate, a heat insulation base, a cover body, a medium leading-in piece, a medium leading-out piece, a conductive piece, first measuring equipment and second measuring equipment, the heated plate is provided with a vacuum bubble-shaped part; the heated plate is connected to the heat insulation base which is provided with a measuring window. The cover body is provided with a circulation groove and connected with the heat insulation base to form a narrow slit channel, and the light transmittance of the cover body is not smaller than 98%. The medium leading-in piece is communicated with one end of the narrow slit channel; the medium leading-out piece is communicated with the other end of the narrow slit channel; the two conductive pieces are connected to the two ends of the heated plate respectively; the first measuring equipment is positioned on one side of the heat-insulating base; the second measuring device is located on one side of the cover body. The thermal-hydraulic parameters of the heated plate and the medium can be conveniently measured based on the simulation system, and a reliable basis can be provided for actual thermal-hydraulic research of the dispersion type fuel element.

Description

Technical Field

[0001] The present application relates to the field of reactor thermal hydraulics and safety technology, and in particular to a system and method for simulating and measuring bubbling on the surface of a dispersed fuel element. Background Art

[0002] The fission gas generated inside the dispersed fuel element under high burnup will cause plastic deformation of the fuel in a localized concentration, resulting in blistering on the surface of the element. As the number of blisters increases, the flow resistance will inevitably increase. At the same time, the fission gas will also increase the local thermal resistance in the fuel element, resulting in deterioration of heat transfer, which in turn affects the integrity of the cladding. At present, there are few studies on the heat transfer performance of dispersed fuel elements under blistering conditions, and most of them are numerical simulation studies. Therefore, it is necessary to design a real-time simulation system for heat transfer under multiple blisters in dispersed fuel elements and its synchronous measurement method, which can be used to carry out experimental research on the coolability of fuel elements after blistering, obtain basic experimental data on the flow heat transfer of fuel elements under blistering conditions, and master the influence law and mechanism of blistering conditions. Summary of the invention

[0003] In view of the problems in the background technology, the present application provides a system and method for simulating and measuring bubbling on the surface of a dispersed fuel element.

[0004] This application is implemented through the following technical solutions:

[0005] In a first aspect, the present application provides a dispersed fuel element surface bubbling simulation measurement system, comprising:

[0006] A heated plate capable of electrical conduction, wherein one surface of the heated plate has a vacuum bubble-like portion;

[0007] An insulating base, the heated plate is connected to a working surface of the insulating base, and the insulating base has a measuring window corresponding to the position of the vacuum bubble and penetrating the insulating base;

[0008] A cover body, wherein the cover body has a flow slot, the cover body is connected to the heat-insulating base so that the heat-insulating base seals the flow slot to form a narrow slit channel, the heated plate is located in the narrow slit channel, and the light transmittance of the cover body is configured to be not less than 98%;

[0009] A medium introduction member, the medium introduction member being in communication with one end of the narrow slit channel;

[0010] A medium outlet member, the medium outlet member being in communication with the other end of the narrow slit channel;

[0011] Conductive members, two of which are connected to two ends of the heated plate respectively;

[0012] a first measuring device, the first measuring device being located at one side of the thermal insulation base to measure the heated plate through the measuring window;

[0013] The second measuring device is located at one side of the cover body to measure the medium in the cover body, and the second measuring device is configured with a laser.

[0014] In some optional embodiments, the first measuring device is configured as an infrared thermal imager.

[0015] In some optional embodiments, the second measuring device is configured as a high-speed camera or a cross-frame camera.

[0016] In some optional embodiments, a synchronizer is further included, and the first measuring device and the second measuring device are respectively connected to the synchronizer.

[0017] In some optional embodiments, the cover body is sealed to the insulation base via a static sealing ring, wherein the static sealing ring is arranged around the flow groove.

[0018] In some optional embodiments, a mounting sink is constructed on the working surface of the thermal insulation base, the heated plate is connected to the mounting sink and one of the plate surfaces is flush with the working surface.

[0019] In some optional embodiments, the heated plate is connected to the inner wall of the mounting sink by filling with sealant.

[0020] In some optional embodiments, the cover is configured as optical quartz glass.

[0021] In some optional embodiments, the insulating base is configured as an insulator.

[0022] In some optional embodiments, the insulating base is configured as a resin body.

[0023] In some optional embodiments, the conductive member is connected to the heated plate by silver brazing.

[0024] In some optional embodiments, an elastic sealing cavity is provided in the insulating base, and the elastic sealing cavity is filled with insulating powder. A temperature measuring hole is also provided on the insulating base so that the thermocouple can pierce the elastic sealing cavity through the temperature measuring hole and contact the heated plate.

[0025] In some optional embodiments, a pressure measuring tube is further included, and the pressure measuring tube is connected to the narrow slit channel.

[0026] In some optional embodiments, the medium inlet and / or medium outlet is equipped with a temperature measuring tube.

[0027] In some optional embodiments, it further includes a first pressure block and a second pressure block arranged at intervals, the first pressure block is connected to the second pressure block, wherein the first pressure block abuts against the base, and the second pressure block abuts against the cover body.

[0028] In some optional embodiments, the heated plate comprises:

[0029] A foaming plate, wherein the foaming plate is formed with a groove by a casting process;

[0030] A heating plate, wherein the heating plate and the bubbling plate are arranged in parallel and spaced apart from each other;

[0031] An insulating layer is located between the blister plate and the heating plate, the insulating layer is connected to the heating plate, and the insulating layer and the blister plate are connected by vacuum diffusion welding to enclose a vacuum bubble portion with the groove on the blister plate.

[0032] In a second aspect, the present application provides a method for simulating and measuring the bubbling on the surface of a dispersed fuel element, which is implemented based on the system for simulating and measuring the bubbling on the surface of a dispersed fuel element described in the first aspect, and includes the following contents:

[0033] Providing a medium so that the medium circulates in the narrow slit channel;

[0034] Providing power to make the heated plate electrically conductive;

[0035] adding tracer particles to the medium;

[0036] Adjust the laser so that the emission direction of the laser coincides with the flow direction of the medium;

[0037] The first measuring device and the second measuring device are started to measure the heated plate and the medium.

[0038] Compared with the prior art, this application has the following advantages and beneficial effects:

[0039] The present application provides a system and method for simulating and measuring bubbling on the surface of a dispersed fuel element. The vacuum bubble-like portion on the heated plate can simulate the structural state of the dispersed fuel element under bubbling, and a narrow channel is formed by connecting the cover body and the insulating base. The medium is allowed to flow in the narrow channel by using a medium inlet member and a medium outlet member, and the heated plate is heated by using a conductive member. At the same time, the heated plate realizes unilateral diffusion of heat into the narrow channel under the insulating effect of the insulating base, and can obtain the same heating conditions and heat transfer conditions as those when the dispersed fuel element is bubbling, and provide a coolant thermal boundary consistent with that when the dispersed fuel element is bubbling, thereby realizing accurate simulation of the heating boundary of the dispersed fuel element and the geometric boundary of the flow channel, and then the temperature parameters of the heated plate can be automatically measured through the measuring window by using the first measuring device, and the medium parameters in the narrow channel can be automatically measured by using the second measuring device. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0041] Figure 1 A simplified structural diagram of a system for simulating and measuring the bubbling on the surface of a dispersed fuel element provided in an embodiment of the present application;

[0042] Figure 2 A schematic diagram of a simulated structure of the bubble state on the surface of a dispersed fuel element provided in an embodiment of the present application;

[0043] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure at AA in the middle;

[0044] Figure 4 A schematic diagram of a cross-sectional structure of a heat-insulating base portion provided in an embodiment of the present application;

[0045] Figure 5 This is a schematic diagram of the heated plate structure provided in an embodiment of the present application.

[0046] Marks and corresponding parts names in the attached drawings:

[0047] 1-medium inlet, 2-medium outlet, 3-second pressure-bearing block, 4-cover, 5-heating plate, 51-foaming plate, 52-heating plate, 53-insulating layer, 6-insulating base, 61-elastic sealing cavity, 62-insulating powder, 7-narrow slit channel, 8-conductive member, 9-first pressure-bearing block, 10-temperature measuring hole, 11-temperature measuring pipe, 12-pressure measuring pipe, 13-first measuring device, 14-second measuring device, 15-laser, 16-synchronizer. DETAILED DESCRIPTION

[0048] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with examples and drawings. The illustrative implementation scheme of the present application and its description are only used to explain the present application and are not intended to limit the present application.

[0049] In the first aspect, the present application provides a system for simulating and measuring the foaming on the surface of a dispersed fuel element, which can be referred to in conjunction with Figure 1 to Figure 4 The dispersion type fuel element surface bubbling simulation measurement system includes a heated plate 5, an insulating base 6, a cover body 4, a medium inlet 1, a medium outlet 2, a conductive member 8, a first measuring device 13 and a second measuring device 14.

[0050] The heated plate 5 can be configured as an electrically conductive material plate. When the heated plate 5 is electrically conductive, the heated plate generates heat by current doing work to simulate the heat release of a diffuse fuel element. For example, the heated plate 5 can be configured as copper, aluminum, iron, nickel-chromium alloy, silicon, germanium, silicon carbide, gallium arsenide, carbon fiber, graphite, carbon nanotubes, ceramic fibers, carbon-based composite plates, etc. One of the surfaces of the heated plate 5 has a vacuum bubble portion, which is manifested as a hollow protrusion on one of the surfaces of the heated plate 5. The vacuum bubble portion can be formed by casting or by connecting two components to each other, and the hollow protrusion contains a vacuum cavity; the number of vacuum bubble portions can be one or more. When the number of vacuum bubble portions is multiple, the multiple vacuum bubble portions can be arranged adjacent to each other, that is, the edges of the vacuum bubble portions are connected, or they can be arranged at intervals, that is, there is a spacing between any two vacuum bubble portions.

[0051] The heated plate 5 is connected to the working surface of the insulating base 6. The specific shape of the insulating base 6 is not limited, and it can be constructed as a rectangular parallelepiped, a triangular prism, a quadrangular prism, a polygonal prism, a sphere or other special shapes; the working surface on the insulating base 6 can be a plane to facilitate the connection with other components, as in the embodiment of the present application, when the heated plate 5 is heated, its plate surface has a large heat diffusion area, and the plate surface of the heated plate 5 can be fitted with the working surface of the insulating base 6 to reduce heat dissipation and realize the unilateral diffusion of heat of the heated plate 5, wherein the vacuum bubble portion is located on the plate surface of the heated plate 5 away from the insulating base 6; the working surface can be obtained by processing, or it can be a plane of the insulating base 6 itself. For example, when the insulating base 6 is constructed as a sphere, a working surface can be obtained on the insulating base 6 by turning, milling, planing and other processing methods. For example, when the insulating base 6 is constructed as a rectangular parallelepiped, one of the side surfaces of the insulating base 6 can be used as the working surface. In actual experimental operations, the insulating base 6 usually needs to be fixed or clamped by other components, so the insulating base 6 can be constructed as a rectangular parallelepiped to facilitate the experimenter to perform necessary operations. At this time, the contour shape of the working surface is a rectangle. Of course, the specific shape of the working surface is not limited. In other embodiments, even if the insulating base 6 is constructed as a rectangular parallelepiped, the contour shape of a triangle, a pentagon, a hexagon or the like can be processed on one of the side surfaces of the insulating base 6. A working surface in a polygonal, star-shaped or other special-shaped shape; the insulating base 6 has a measuring window corresponding to the position of the vacuum bubble and passing through the insulating base 6, the measuring window can be configured as a rectangular through hole, the size of the rectangular through hole can be adaptively designed, and its specific size is configured so that when the heated plate 5 is heated to the expected maximum value, the bending deformation of the portion of the heated plate 5 corresponding to the position of the measuring window is within an allowable range; an elastic sealing cavity 61 is provided in the insulating base 6, the elastic sealing cavity 61 can be made of rubber or silicone material, and the elastic sealing cavity 61 is filled with insulating powder 62. In actual implementation, the insulating powder 62 can be configured as glass fiber powder, and the insulating base 6 is also provided with The thermocouple can pierce the elastic sealing cavity 61 through the temperature measuring hole 10 and contact the heated plate 5. In actual implementation, a puncture hole with a diameter much smaller than that of the thermocouple can be opened on the elastic sealing cavity 61. Due to the material properties of the elastic sealing cavity 61 itself, after the thermocouple pierces the elastic sealing cavity 61, the hole wall of the puncture hole can be tightly attached to the thermocouple due to its own elastic deformation. At the same time, the thermal insulation powder 62 in the elastic sealing cavity 61 is more compact under the pressure of the thermocouple, which means that the thermal insulation powder 62 can also be tightly attached to the thermocouple. Of course, since the thermal insulation powder 62 is compressed, the cavity wall of the elastic sealing cavity 61 will also be compressed by the thermal insulation powder 62 to undergo a certain elastic deformation.After the temperature measurement is completed, the thermocouple is taken out, and the puncture hole of the elastic sealing cavity 61 returns to its original shape under the action of elastic deformation, and the internal thermal insulation powder 62 is compressed under the elastic action of the cavity wall of the elastic sealing cavity 61, causing the thermal insulation powder 62 to flow into the hole formed by the thermocouple, which means that under the elastic action of the elastic sealing cavity 61, the thermal insulation powder 62 can be self-filled, thereby providing better thermal insulation for the heated plate 5, avoiding heat loss of the heated plate 5, and ensuring that the thermal boundary of the coolant in the narrow slit channel 7 is basically consistent with the actual working condition. In the normal viewing angle of the plate surface of the heated plate 5, a plurality of temperature measuring holes 10 are arranged at intervals to perform multi-point temperature measurement of the heated plate 5, which is conducive to analyzing the temperature distribution of the heated plate 5 under the working state. Among them, the extension direction of the temperature measuring hole 10 can be unlimited, such as a straight line, a broken line, a curve or a combination of any two / three of the foregoing. In order to reduce the temperature measuring hole 10 is the length of the temperature measuring hole 10 in its extension direction. The extension direction of the temperature measuring hole 10 can be a straight line, wherein the extension direction of the temperature measuring hole 10 can be perpendicular to the plate surface of the heated plate 5 or form an angle. In actual implementation, it is preferred to set the extension direction of the temperature measuring hole 10 to be perpendicular to the plate surface of the heated plate 5, so as to ensure that the length of the temperature measuring hole 10 in the extension direction is short enough, so that the temperature measurement of the heated plate 5 can be conveniently performed in the temperature measuring hole 10. When the temperature measuring hole 10 is not working, it can be isolated. The shorter temperature measuring hole 10 can ensure that there is less heat exchange medium inside in the isolated state, such as air, so as to reduce its influence on the local temperature of the heated plate 5 during the test; the cross-sectional shape of the temperature measuring hole 10 can be unlimited, such as triangle, rectangle, square, circle, heart, star or other special shapes. In actual implementation, the temperature measuring hole 10 can be set as a circular straight hole. ;

[0052] The cover body 4 has a circulation groove, and the cover body 4 is connected to the insulating base 6 so that the insulating base 6 seals the circulation groove to form a narrow slit channel 7, and the heated plate 5 is located in the narrow slit channel 7, that is, for the cover body 4 and the heated plate 5, the heated plate 5 can be placed in the circulation groove; the specific form of the circulation groove is not limited, it can be a closed groove body on the cover body 4, that is, there is only one groove, or it can be an open groove body, that is, the circulation groove can penetrate the cover body 4 to form two / three grooves; in actual implementation, the circulation groove can be set as a closed groove body, so that after the cover body 4 is connected to the insulating base 6, the insulating base 6 can easily seal the circulation groove through the working surface to form a narrow slit channel 7. Of course, in other embodiments, if the circulation groove is set as an open groove body, then after the cover body 4 is connected to the insulating base 6, other grooves can be sealed separately or other grooves can be connected to it. The other components are sealed and connected; the specific shape of the circulation groove may not be limited, such as triangle, rectangle, square, circle or other special shapes; since a narrow slit channel 7 for the medium to flow will be formed between the circulation groove and the insulating base 6, it is preferred to set the circulation groove to a trough shape with a certain length, such as a rectangular trough body, a square trough body, a prismatic trough body, preferably, the circulation groove is set to a rectangular trough body or a square trough body, that is, from the perspective of the length direction of the circulation groove, the contour shape of the circulation groove is square or rectangular, wherein, when the circulation groove is set to a rectangular trough body or a square trough body, its extension direction can be a straight line or a curve, in actual implementation, the extension direction of the circulation groove can be set to a straight line to ensure that the medium has a stable flow state in the narrow slit channel 7, and in other embodiments, as needed, the extension direction of the circulation groove can also be set to a curve or a combination of a curve and a straight line. When the circulation slot is set as a rectangular slot body or a square slot body, the heated plate 5 can be set as a rectangular plate body, that is, the thickness of the heated plate 5 is uniform except for the position of the vacuum bubble portion. At this time, the overall shape of the narrow slit channel 7 formed by the circulation slot and the insulating base 6 is a rectangular parallelepiped, which is conducive to the centering of the heated plate 5 in the narrow slit channel 7, ensuring that the heat can be evenly diffused in the narrow slit channel 7 and ensuring that the medium is evenly heated in the flow direction; the light transmittance of the heated plate 5 is configured to be not less than 98%, that is, the medium in the narrow slit channel 7 can be visualized from the outside of the cover body 4.

[0053] The medium introduction member 1 is connected to one end of the narrow slit channel 7; when the circulation slot is set as a closed slot body, the medium introduction member 1 can pass through the insulation base 6 to communicate with the narrow slit channel 7, and the medium introduction member 1 is sealed and connected to the insulation base 6; when the circulation slot is set as an open slot body, the medium introduction member 1 can be directly sealed and connected to the unclosed slot in the circulation slot. The medium introduction member 1 is usually used for injecting coolant.

[0054] The medium outlet component 2 is connected to the other end of the narrow slit channel 7; when the circulation slot is set as a closed slot body, the medium outlet component 2 can pass through the insulating base 6 to be connected to the narrow slit channel 7, and the medium outlet component 2 is sealed to the insulating base 6; when the circulation slot is set as an open slot body, the medium outlet component 2 can be directly sealed to the unclosed slot in the circulation slot.

[0055] The two conductive members 8 are respectively connected to the two ends of the heated plate 5. The conductive members 8 can be configured as copper bars, aluminum bars, stainless steel bars, zinc alloy bars, copper alloy bars, plastic conductive bars, etc. In actual implementation, the two conductive members 8 can be the same or different. Preferably, the two conductive members 8 can be configured as copper bars. Copper bars have excellent electrical conductivity, can reduce heat loss, and have good mechanical strength, corrosion resistance, high flexibility and good welding performance; the vacuum bubble portion is located between the two conductive members 8, that is, when the heated plate 5 is set as a rectangular plate body, the two conductive members 8 can be connected at both ends of the heated plate 5 in the length direction, and in the length direction of the heated plate 5, the vacuum bubble portion can be located in the middle position of the two conductive members 8. Of course, in other embodiments, the vacuum bubble portion can also be located at other positions between the two conductive members 8.

[0056] The first measuring device 13 is located on one side of the insulating base 6 to facilitate the measurement of the heated plate 5. Specifically, the first measuring device 13 can measure the temperature of the corresponding position of the vacuum bubble portion on the heated plate 5 through the measuring window. The first measuring device 13 can be a contact measurement or a non-contact measurement. In actual implementation, the first measuring device 13 can be configured as an infrared thermal imager.

[0057] The second measuring device 14 is located on one side of the cover body 4 to facilitate the measurement of the medium in the narrow slit channel 7. The second measuring device 14 is a non-contact measurement. The second measuring device 14 is configured with a laser 15, and the laser 15 can be used to emit laser into the narrow slit channel 7, so that the second measuring device 14 can measure the medium. In actual implementation, the second measuring device 14 can be configured as a high-speed camera or a cross-frame camera, and the laser 15 is used to inject a sheet of light into the narrow slit channel 7 so that the second measuring device 14 can perform visual observation of the medium in the narrow slit channel 7.

[0058] The embodiment of the present application provides a dispersion type fuel element surface bubbling simulation measurement system, the vacuum bubble portion on the heated plate 5 can simulate the structural state of the dispersion type fuel element under bubbling conditions, after the two conductive parts 8 are connected to the power supply and the medium inlet 1 and the medium outlet 2 are connected to the medium circulation system, the heated plate 5 is electrically conducted to generate heat, thereby achieving a temperature increase, due to the insulation effect of the insulation base 6, most of the heat of the heated plate 5 is dissipated to the narrow slit channel 7 on one side to heat the medium in the narrow slit channel 7, thereby simulating the working state of the fluid in the dispersion type fuel element, and the first measuring device 13 can measure the temperature of the corresponding position of the vacuum bubble portion on the heated plate 5 through the measuring window. The temperature field at the corresponding position of the vacuum bubble on the heated plate 5 can be obtained by measuring at the same time, and the heated plate 5 can be measured at multiple points through the temperature measuring hole 10 as needed to obtain the approximate temperature field distribution on the heated plate 5. The measurement values ​​between the temperature measuring hole 10 and the first measuring device 13 are also calibrated with each other. The second measuring device 14 can clearly visualize the fluid in the narrow slit channel 7 with the assistance of the laser 15. For example, by adding tracer particles to the fluid, the tracer particles will reflect the laser under the irradiation of the laser, and the particle displacement image can be taken by a cross-frame camera or a high-speed camera, so as to obtain parameters such as the medium velocity field, thereby providing technical support for the precise formulation of thermal hydraulic design and safety criteria of dispersed fuel elements.

[0059] Compared with the existing three-dimensional numerical simulation method, the dispersed fuel element surface bubble simulation measurement system provided in the embodiment of the present application can perform direct measurement, has relatively less calculation amount, is relatively more convenient to implement, the data is more intuitive and easier to obtain, and the measurement results are quite credible.

[0060] In some optional embodiments, the dispersed fuel element surface bubble simulation measurement system can also be configured with a synchronizer 16, and the first measuring device 13 and the second measuring device 14 are respectively connected to the synchronizer 16, so that the measurement frequency, measurement period, etc. of the first measuring device 13 and the second measuring device 14 can be controlled by the synchronizer 16.

[0061] There are various ways of sealing the connection between the cover body 4 and the insulating base 6, for example, adhesive sealing, welding sealing, magnetic sealing, and threaded sealing can be used. Considering the maintainability of the entire device, in some optional embodiments, the cover body 4 is sealed and connected to the insulating base 6 through a static sealing ring. The static sealing ring can be configured as a rubber sealing ring, a metal sealing ring, a polytetrafluoroethylene sealing ring, a graphite sealing ring, etc. In actual implementation, a suitable static sealing ring can be selected according to the thermal conductivity of the cover body 4. For example, if the thermal conductivity of the cover body 4 is low, a static sealing ring with average heat resistance, such as a rubber sealing ring, can be selected. When the thermal conductivity of the cover body 4 is high, a static sealing ring with high heat resistance, such as a graphite sealing ring, can be selected. In actual implementation, it is usually expected that the thermal conductivity of the cover body 4 is low. In order to avoid a large amount of heat loss in the narrow slit channel 7, that is, in the working state, the temperature of the cover body 4 will not be too high, and the static sealing ring can be configured as a low-cost static sealing ring such as a rubber sealing ring; wherein, the static sealing ring is arranged around the circulation groove, and the shape of the static sealing ring can be not limited. For example, the static sealing ring can be such as rectangular, circular, triangular, diamond, etc., and can be specifically designed according to the adaptability of the notch of the circulation groove to avoid a large slit space after the cover body 4 is connected to the insulating base 6; for example, when the circulation groove is a rectangular groove body, its notch is rectangular, and the static sealing ring can be configured as a rectangle. Of course, in other embodiments, according to needs, such as different installation conditions and different processing accuracy, the shape of the static sealing ring can also be other special shapes.

[0062] After the heated plate 5 is connected to the insulating base 6, we prefer that the heated plate 5 has a single heat dissipation area to facilitate the control of the heat dissipation direction of the heated plate 5, for example, one of the plate surfaces of the heated plate 5 is in the narrow slit channel 7, while the other surfaces are relatively isolated from the narrow slit channel 7, so that the heat of the heated plate 5 can be basically dissipated from one of the plate surfaces of the heated plate 5 to the narrow slit channel 7. Therefore, in some optional embodiments, a mounting sink is constructed on the working surface of the insulating base 6, and the heated plate 5 is connected to the mounting sink and one of the plate surfaces is flush with the working surface. As a result, the other surfaces of the heated plate 5 are in contact with the insulating base 6, and the heat dissipation area of ​​the heated plate 5 in the narrow slit channel 7 is reduced, that is, the plate surface of the vacuum bubble portion is used as the heat dissipation surface. In this way, the heat dissipation direction of the heated plate 5 is certain, which is conducive to the analysis of the heat dissipation characteristics of the heated plate 5, and to the prediction of the heat distribution in the narrow slit channel 7, and can provide a certain theoretical basis for the experimental results.

[0063] The dispersed fuel element surface bubbling simulation measurement system provided in the embodiment of the present application realizes the external placement of the temperature measuring element (i.e., thermocouple). Compared with the existing concept of placing the temperature measuring element inside, the temperature measuring element in the present application does not need to be in a high-temperature working environment for a long time, which is beneficial to ensure the service life and measurement accuracy of the temperature measuring element; and the present application can conveniently use temperature measuring elements of different precisions to measure the heated plate 5 to meet various test requirements during the test, and has relatively good applicability; after the measurement is completed, the elastic sealing cavity 61 can restore its original state under the action of its own elasticity, and under the elastic action of the elastic sealing cavity 61, the internal insulation powder 62 completes self-filling at the same time, which can prevent the heat loss of the heated plate 5 in a non-measurement environment, ensure that the thermal boundary of the coolant in the narrow slit channel 7 is basically consistent with the actual working condition, and thus ensure the accuracy of the test results.

[0064] The connection between the heated plate 5 and the insulating base 6 may not be limited, as long as it is ensured that the heated plate 5 can be fitted with the insulating base 6 surface to achieve a good insulation effect. However, due to the influence of processing accuracy, there may be a certain gap between the heated plate 5 and the insulating base 6 surface to surface. If the gap is a slit connected to the narrow slit channel 7, it may have a certain impact on the temperature of the local medium in the narrow slit channel 7, which will be detrimental to the detailed study of the heat transfer characteristics of the local medium in the narrow slit channel 7. Therefore, in some optional embodiments, the heated plate 5 and the inner wall of the mounting sink are connected by filling with sealant. The sealant can be a relatively heat-resistant sealant to prevent deformation due to excessive temperature and affect the sealing effect between the heated plate 5 and the sealant. It can be configured as silicone sealant, polyurethane sealant, fluororubber sealant, polytetrafluoroethylene sealant, high-temperature silicate sealant, etc.

[0065] In some optional embodiments, the cover body 4 is configured as optical quartz glass. The optical quartz glass has a relatively low thermal conductivity in addition to having a relatively good light transmittance performance, which can reduce the heat loss of the medium in the narrow slit channel 7 .

[0066] In the process of the heated plate 5 being electrically turned on, we hope that the current has a better effective power, that is, the current basically only does work on the heated plate 5. Therefore, in some optional embodiments, the insulating base 6 is configured as an insulator, so as to greatly reduce power loss and ensure the safety of electricity use during the test. Preferably, the insulating base 6 can be configured as a resin body. In other embodiments, the material used for the insulating base 6 can also be configured as a ceramic material, a fiber-reinforced ceramic-based material, a graphene material, etc. as needed.

[0067] The conductive member 8 is usually connected to other devices with conductive requirements by welding. The heated plate 5 in the embodiment of the present application has a relatively high temperature in the working state, so the welding between the conductive member 8 and the heated plate 5 should have a certain heat resistance. Therefore, in some optional embodiments, the conductive member 8 is connected to the heated plate 5 by silver brazing. The thermal expansion coefficient of silver is smaller than that of copper, which means that when the temperature changes, the thermal stress generated by the silver brazing connection point is relatively small, which helps to reduce the risk of loose connection, and silver has good corrosion resistance, especially in high temperature environment, which helps to extend the service life of the welding part and ensure the conductive performance of the conductive member 8 and the heated plate 5.

[0068] In some optional embodiments, the dispersion type fuel element surface bubbling simulation measurement system further includes a pressure measuring pipe 12, and the pressure measuring pipe 12 is connected to the narrow slit channel 7. In actual implementation, the pressure measuring pipe 12 passes through the insulation base 6 and is connected to the narrow slit channel 7. The number of the pressure measuring pipes 12 can be configured as two. In the flow direction of the medium, the two pressure measuring pipes 12 are respectively located on both sides of the vacuum bubble. Preferably, the two pressure measuring pipes 12 are respectively arranged close to the medium inlet 1 and the medium outlet 2. Through the arrangement of the pressure measuring pipe 12, the medium pressure in the narrow slit channel 7 can be measured, and the change characteristics of the medium pressure on both sides of the vacuum bubble can be obtained, which is conducive to the study of the influence of the vacuum bubble on the medium pressure under the heat generation state.

[0069] In some optional embodiments, the medium inlet 1 and / or the medium outlet 2 are provided with a temperature measuring pipe 11. In actual implementation, the temperature measuring pipe 11 can be provided on both the medium inlet 1 and the medium outlet 2. The temperature measuring pipe 11 can be conveniently provided to measure / monitor the medium temperature before the medium enters the narrow slit channel 7 and after the medium flows out of the narrow slit channel 7, which can bring convenience to the measurement process and facilitate the acquisition of the dynamic change characteristics of the medium temperature under long-term operation.

[0070] In some optional embodiments, the dispersed fuel element surface bubble simulation measurement system also includes a first pressure block 9 and a second pressure block 3 arranged at intervals, and the first pressure block 9 is connected to the second pressure block 3, wherein the first pressure block 9 abuts against the base, and the second pressure block 3 abuts against the cover body 4.

[0071] In the embodiment of the present application, by setting the first pressure-bearing block 9 and the second pressure-bearing block 3, the cover body 4 and the insulating base 6 can be pressed together, so as to ensure the stability of the sealing performance between the cover body 4 and the insulating base 6. The first pressure-bearing block 9 and the second pressure-bearing block 3 can both be constructed as a cuboid, the first pressure-bearing block 9 can form a covering on the insulating base 6, the second pressure-bearing block 3 can form a covering on the cover body 4, and an observation window can be provided on the second pressure-bearing block 3 so that the second measuring device 14 can visually measure the medium in the narrow slit channel 7. In the normal direction of the plate surface of the heated plate 5, the vacuum bubble portion is located within the range encompassed by the observation window, and the first pressure-bearing block 9 and the second pressure-bearing block 3 can be fastened and connected by bolts. Among them, the temperature measuring pipe 11, the conductive part 8, the pressure measuring pipe 12, the medium inlet 1 and the medium outlet 2 can all pass through the first pressure-bearing block 9 and the insulating base 6 in sequence to communicate with the narrow slit channel 7 or connect with the heated plate 5.

[0072] In some optional embodiments, see Figure 5 The heated plate includes a blister plate 51, a heating plate 52 and an insulating layer 53; the blister plate 51 is formed with a groove through a casting process; the heating plate 52 and the blister plate 51 are arranged in parallel and spaced apart; the insulating layer 53 is located between the blister plate 51 and the heating plate 52, the insulating layer 53 is connected to the heating plate 52, and the insulating layer 53 is connected to the blister plate 51 through vacuum diffusion welding to enclose a vacuum bubble portion with the groove on the blister plate 51.

[0073] When the heated plate provided in the present application is used in an experimental device for simulating the heat transfer characteristics under the condition of bubbling on the surface of a diffuse fuel element, since the heating plate 52 relies on power to generate heat to simulate the heating of the diffuse fuel element, through the setting of the insulating layer 53, the current only passes through the heating plate 52 and does not pass through the bubbling plate 51, thereby truly simulating the distribution of heat sources in the prototype fuel element. It can avoid the situation where the self-heating of the bubbling plate 51 affects the temperature field near the vacuum bubble portion, that is, reduces the influencing factors of the temperature field near the vacuum bubble portion, facilitates subsequent theoretical analysis, and ensures the accuracy and credibility of the experimental results; and the insulating layer 53 is connected to the bubbling plate 51 by vacuum diffusion welding, and the connecting part has the characteristic of high temperature resistance, which is suitable for the bubbling temperature environment on the surface of the diffuse fuel element.

[0074] In actual implementation, the bubble plate 51 is configured as an Inconel625 plate, so that the thermal conductivity of the bubble plate 51 can be close to the parameters of the zirconium alloy cladding in the dispersed fuel element, and the thickness of the bubble plate 51 is configured to be no more than 1 / 10 of the thickness of the heating plate 52; the portion of the heating plate 52 used for conduction is configured as an S32168 plate to ensure better resistance to intergranular corrosion and high temperature strength, wherein the heating plate 52 as a whole can be configured as an S32168 plate; the insulating layer 53 can be formed by coating an aluminum nitride ceramic layer on the surface of the heating plate 52 using a PVD process, and the insulating layer 53 can be formed by coating an aluminum nitride ceramic layer on the surface of the heating plate 52 using a PVD process. The thickness of layer 53 is 30 to 50 μm to meet the requirement of not exceeding 1 / 10 of the thickness of the blister plate 51, so as to achieve effective insulation under the operating conditions of the maximum voltage of 50V in the experiment; the resistivity of the blister plate is much higher than that of the heating plate. In this way, if cracks appear in the insulating layer 53 during the diffusion welding process or during use, the heat generated by the blister plate 51 will not exceed 5% of the total heat generated by electrical conduction. The heat generated by the blister plate 51 affects the temperature field of the vacuum bubble part within an acceptable range, so that the experimental device has a certain ability to resist abnormalities, thereby ensuring the success rate of the experiment.

[0075] In a second aspect, an embodiment of the present application provides a method for simulating and measuring the bubbling on the surface of a dispersed fuel element, which is implemented based on the system for simulating and measuring the bubbling on the surface of a dispersed fuel element described in the first aspect, and includes the following contents:

[0076] S1. Provide a medium so that the medium circulates in the narrow slit channel 7.

[0077] During actual implementation, the medium inlet 1 and the medium outlet 2 are respectively connected to the medium circulation system.

[0078] S2. Provide power to make the heated plate 5 electrically conductive.

[0079] That is, the two conductive members 8 are respectively connected to the power source / electric power system.

[0080] S3. Add tracer particles to the medium.

[0081] S4. Adjust the laser 15 so that the emission direction of the laser 15 coincides with the flow direction of the medium.

[0082] The tracer particles in the medium can reflect light and output visual signals under the irradiation of laser.

[0083] S5, start the first measuring device 13 and the second measuring device 14 to measure the heated plate 5 and the medium.

[0084] Among them, the first measuring device 13 can be configured as an infrared thermal imager, and the second measuring device 14 can be configured as a high-speed camera or a cross-frame camera; before starting the second measuring device 14, the second measuring device 14 is first adjusted so that its shooting direction is perpendicular to the surface of the heated plate 5 to avoid unnecessary measurement errors caused by refraction of the light path.

[0085] During actual implementation, a data acquisition system can also be provided. The data acquisition system can be configured as a computer, an industrial computer, etc. The data acquisition system is used to collect parameters measured by the first measuring device 13 and the second measuring device 14. The data acquisition system is also used to collect temperature parameters and pressure parameters of the medium at the temperature measuring connection pipe 11 and the pressure measuring connection pipe 12.

[0086] The above specific embodiments illustrate the implementation methods of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Although the description of the present application will be introduced in conjunction with some embodiments, this does not mean that the features of this application are limited to the implementation methods. On the contrary, the purpose of introducing the application in conjunction with the implementation methods is to cover other options or modifications that may be extended based on the claims of the present application. In order to provide an in-depth understanding of the present application, the above description contains many specific details. The present application can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present application, some specific details will be omitted in the description. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0087] It should be noted that in this specification, similar numbers and letters represent similar items in the above drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of this application, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0088] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A dispersion type fuel element surface bubbling simulation measurement system, characterized in that: include: A heated plate (5) capable of electrical conduction, wherein one plate surface of the heated plate (5) has a vacuum bubble portion; an insulating base (6), the heated plate (5) being connected to a working surface of the insulating base (6), the insulating base (6) having a measuring window corresponding to the position of the vacuum bubble portion and penetrating the insulating base (6); A cover body (4), the cover body (4) having a flow slot, the cover body (4) being connected to the heat-insulating base (6) so that the heat-insulating base (6) seals the flow slot to form a narrow slit channel (7), the heated plate (5) being located in the narrow slit channel (7), and the light transmittance of the cover body (4) being configured to be not less than 98%; A medium introduction member (1), the medium introduction member (1) being in communication with one end of the narrow slit channel (7); A medium outlet (2), the medium outlet (2) being in communication with the other end of the narrow slit channel (7); Conductive members (8), two of the conductive members (8) being respectively connected to two ends of the heated plate (5); A first measuring device (13), the first measuring device (13) being located on one side of the heat-insulating base (6) for measuring the heated plate (5) through the measuring window; A second measuring device (14), the second measuring device (14) is located on one side of the cover body (4) to measure the medium in the cover body (4), and the second measuring device (14) is equipped with a laser (15).

2. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: The first measuring device (13) is configured as an infrared thermal imager.

3. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: The second measuring device (14) is configured as a high-speed camera or a cross-frame camera.

4. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: It also includes a synchronizer (16), and the first measuring device (13) and the second measuring device (14) are respectively connected to the synchronizer (16).

5. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: The cover body (4) is sealedly connected to the thermal insulation base (6) via a static sealing ring, wherein the static sealing ring is arranged around the flow groove.

6. The dispersed fuel element surface bubbling simulation measurement system according to claim 1 or 5, characterized in that: A mounting sink is constructed on the working surface of the heat-insulating base (6), the heated plate (5) is connected to the mounting sink and one of the plate surfaces is flush with the working surface.

7. The dispersed fuel element surface bubbling simulation measurement system according to claim 6, characterized in that: The heated plate (5) is connected to the inner wall of the mounting sink by filling with sealant.

8. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: The cover body (4) is configured as optical quartz glass.

9. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: The insulating base (6) is configured as an insulator.

10. The dispersed fuel element surface bubbling simulation measurement system according to claim 9, characterized in that: The heat insulating base (6) is configured as a resin body.

11. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: The conductive member (8) is connected to the heated plate (5) by silver brazing.

12. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: An elastic sealing cavity (61) is arranged in the insulating base (6), and the elastic sealing cavity (61) is filled with insulating powder (62). A temperature measuring hole (10) is also provided on the insulating base (6), so that a thermocouple can pierce the elastic sealing cavity (61) through the temperature measuring hole (10) and contact the heated plate (5).

13. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: It also comprises a pressure measuring pipe (12), wherein the pressure measuring pipe (12) is in communication with the narrow slit channel (7).

14. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: The medium inlet (1) and / or the medium outlet (2) are provided with a temperature measuring connection pipe (11).

15. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: It also comprises a first pressure-bearing block (9) and a second pressure-bearing block (3) arranged at intervals, wherein the first pressure-bearing block (9) is connected to the second pressure-bearing block (3), wherein the first pressure-bearing block (9) abuts against the base, and the second pressure-bearing block (3) abuts against the cover body (4), and an observation window is provided on the second pressure-bearing block (3).

16. The dispersed fuel element surface bubbling simulation measurement system according to claim 1, characterized in that: The heated plate (5) comprises: A blister plate (51), wherein the blister plate (51) is formed with a groove through a casting process; A heating plate (52), the heating plate (52) and the bubbling plate (51) are arranged in parallel and at intervals; An insulating layer (53), the insulating layer (53) is located between the blister plate (51) and the heating plate (52), the insulating layer (53) is connected to the heating plate (52), and the insulating layer (53) is connected to the blister plate (51) by vacuum diffusion welding so as to enclose a vacuum bubble portion with the groove on the blister plate (51).

17. A method for simulating and measuring the bubbling on the surface of a dispersed fuel element, implemented based on the system for simulating and measuring the bubbling on the surface of a dispersed fuel element according to claims 1 to 16, characterized in that: Includes the following: Providing a medium so that the medium circulates in the narrow slit channel (7); Providing power to make the heated plate (5) electrically conductive; adding tracer particles to the medium; Adjusting the laser (15) so that the emission direction of the laser (15) coincides with the flow direction of the medium; The first measuring device (13) and the second measuring device (14) are activated to measure the heated plate (5) and the medium.

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