A mosaic sandwich type irradiation test device suitable for fine particle type fuel

Abstract

The application discloses a mosaic sandwich type irradiation test device suitable for fine particle type fuel, which comprises an irradiation device and a plurality of irradiation test pieces, the irradiation device is internally provided with a containing cavity, and the irradiation device is provided with an air inlet pipe and an air outlet pipe which are in communication with the inside of the containing cavity; the plurality of irradiation test pieces are fixedly arranged in the containing cavity through fixing assemblies, and the irradiation test pieces are internally provided with helium cavities, air gaps are arranged between the outer sides of the irradiation test pieces and the inner sides of the containing cavities, particle fuels are placed in the helium cavities, and the irradiation test pieces are provided with gas sampling pipes which are in communication with the helium cavities; the particle fuels are placed in the irradiation test pieces, then mixed gas is introduced into the air gaps between the irradiation test pieces and the irradiation device, the temperature control and adjustment of the fuel particles in the irradiation test pieces are realized by changing the thermal resistance of the air gaps, and therefore the purpose of simultaneously carrying out in-pile tests on a large quantity of different kinds of particle fuels can be achieved.

Description

Technical Field

[0001] This invention relates to the field of reactor irradiation technology, specifically to an embedded sandwich-type irradiation test device suitable for fine particulate fuel. Background Technology

[0002] To simplify fuel manufacturing processes and develop mixed oxide fuels (MOXs) that facilitate the combustion of actinides or plutonium, domestic and international institutions have conducted research on pellet-type ceramic fuels. Pellet-type fuel elements have the same shape as traditional fuel rods, but the fuel cladding contains uniformly filled large-diameter and small-diameter fuel particles, compacted through vibration. This type of fuel allows for simpler, dust-free fuel manufacturing processes, simplifying steps such as pulverization, extrusion, and grinding, thereby effectively reducing dirt and material loss. Furthermore, small-diameter spherical TRISO fuel particles are also widely used in gas-cooled reactors.

[0003] To study the thermal properties, particle cracking, and fission gas release of pellet fuels of different sizes, manufacturing processes, and actinide doping contents at different burnup levels, it is necessary to conduct in-reactor irradiation tests and post-irradiation detection to determine their specific performance.

[0004] In practical research, it is necessary to establish irradiation testing techniques for pellet fuel to realistically simulate the operating environment of pellet fuel prototypes in the reactor core. Simultaneously, it is necessary to address the need for large-scale in-reactor testing of different types of pellet fuel to facilitate process selection and fuel performance studies. Summary of the Invention

[0005] The technical problem to be solved by this invention is the lack of a device for simultaneously testing large quantities of pellet fuel. The purpose is to provide an embedded sandwich-type irradiation test device suitable for fine pellet fuel, thereby achieving the goal of realistically simulating the use environment of the pellet fuel prototype in the reactor core.

[0006] This invention is achieved through the following technical solution:

[0007] An embedded sandwich-type irradiation test apparatus suitable for fine particulate fuels includes:

[0008] An irradiation device having an internal cavity, and an inlet pipe and an outlet pipe communicating with the interior of the cavity.

[0009] Multiple irradiation test specimens are fixedly installed in the accommodating cavity of the irradiation device by a fixing assembly, and a helium cavity is provided inside the irradiation test specimen. An air gap is provided between the outer side of the irradiation test specimen and the inner side of the accommodating cavity. Particle fuel is placed in the helium cavity of the irradiation test specimen, and a gas sampling tube communicating with the helium cavity is provided on the irradiation test specimen.

[0010] Preferably, the air gap thickness between the outer surface of different irradiated test specimens and the inner surface of the accommodating cavity is not equal.

[0011] Specifically, the irradiation device includes:

[0012] Outer tube;

[0013] The upper cap is connected to the upper end of the outer sleeve;

[0014] The lower end cap is connected to the lower end of the outer sleeve;

[0015] The air inlet pipe and the air outlet pipe are connected to the upper end cover or the lower end cover and communicate with the interior of the outer sleeve. The irradiated test specimen is placed inside the outer sleeve.

[0016] Specifically, multiple irradiated test specimens are axially stacked within the accommodating cavity;

[0017] The fixing component includes:

[0018] The upper support member has its lower end in contact with the irradiated test specimen, and its upper end is connected to the lower side of the upper end cover.

[0019] The lower support member has its upper end in contact with the irradiated test specimen, and the lower end of the upper support member is connected to the upper side of the lower end cover.

[0020] Furthermore, an annular heat insulation element is provided between two adjacent irradiation test specimens; the fixing assembly also includes:

[0021] An upper heat insulation plate is disposed between the irradiated test specimen and the lower end of the upper support member;

[0022] The lower heat insulation plate is disposed between the upper end of the irradiated test specimen and the lower support member.

[0023] Specifically, the irradiated test specimen includes:

[0024] An outer tube is coaxially disposed inside the outer sleeve, and the outer diameter of the outer tube is smaller than the inner diameter of the outer sleeve;

[0025] An inner tube is coaxially disposed inside the outer tube, and the cavity between the inner side of the outer tube and the outer side of the inner tube is configured as the helium cavity.

[0026] An annular upper cover plate, wherein the inner ring of the upper cover plate is connected to the upper end of the inner tube, and the outer ring of the upper cover plate is connected to the upper end of the outer tube;

[0027] A ring-shaped lower cover plate, wherein the inner ring of the lower cover plate is connected to the lower end of the inner tube, and the outer ring of the lower cover plate is connected to the lower end of the outer tube;

[0028] A fuel fixing component is disposed within the helium cavity, and the fuel fixing component has a placement cavity, within which the particulate fuel is fixed.

[0029] The placement cavity is connected to the helium cavity, and the helium cavity is connected to the gas sampling tube.

[0030] Specifically, the fuel fixing member includes:

[0031] The lower plate is annular, with its lower side tightly fitted to the lower cover plate. The outer side of the lower plate is fitted to the inner side of the outer tube. The upper side of the lower plate is provided with an annular groove, and the inner side of the lower plate is provided with a ventilation opening connecting the annular groove and the helium cavity.

[0032] The upper plate is annular, with its lower side surface fitting against the upper side surface of the lower plate, and the outer side surface of the upper plate fitting against the inner side surface of the outer tube.

[0033] A soft metal layer is laid flat within the annular groove, and the particulate fuel is embedded within the soft metal layer.

[0034] Specifically, the depth of the annular groove is greater than the diameter of the particulate fuel, the thickness of the soft metal layer is less than the diameter of the particulate fuel, and when the particulate fuel is embedded in the soft metal layer, the particulate fuel is tangent to the lower side of the upper plate.

[0035] A gap is provided between the inner side of the lower plate and the inner side of the upper plate and the outer side of the inner tube.

[0036] Furthermore, the irradiation test specimen also includes an inner thermocouple and an outer thermocouple. Both the inner thermocouple and the outer thermocouple are used to measure the temperature of the lower plate, and the distance between the measuring point of the inner thermocouple and the inner surface of the lower plate is less than the distance between the measuring point of the outer thermocouple and the inner surface of the lower plate.

[0037] Optionally, the outer sleeve, the outer tube, the inner tube, and the air intake tube are all coaxially arranged;

[0038] The gas sampling tube is disposed inside the inner tube and passes through the inner tube to communicate with the helium cavity;

[0039] The signal leads of the outer thermocouple, the signal leads of the inner thermocouple, and the gas sampling tube all pass through the inner tube and the gas inlet tube and are located outside the irradiation test device.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] This invention sets up multiple irradiation test pieces inside an irradiation device, places particulate fuel inside the irradiation test pieces, and then introduces a mixed gas into the air gap between the irradiation test pieces and the irradiation device. By changing the thermal resistance of the air gap, the temperature of the fuel particles inside the irradiation test pieces can be controlled and regulated, thereby achieving the purpose of simultaneous in-pile testing of large quantities of different types of particulate fuels. Attached Figure Description

[0042] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0043] Figure 1 This is a schematic diagram of the structure of an embedded sandwich-type irradiation test apparatus suitable for fine particulate fuels according to the present invention.

[0044] Figure 2 This is a schematic diagram of the structure of the irradiation test specimen according to the present invention.

[0045] Reference numerals: 1-Inlet pipe; 2-Upper end cap; 3-Outer sleeve; 4-Upper support component; 5-Upper heat insulation plate; 6-Air gap; 7-Irradiation test specimen; 8-Lower heat insulation plate; 9-Lower support component; 10-Lower end cap; 11-Annular heat insulation component; 12-Outlet pipe; 13-Signal lead wire;

[0046] 101-Outer tube; 102-Upper cover plate; 103-Gas sampling tube; 104-Inner tube; 105-Lower cover plate; 106-Inner thermocouple; 107-Outer thermocouple; 108-Lower plate; 109-Soft metal layer; 110-Particle fuel; 111-Upper plate; 112-Ventilation notch; 113-Helium cavity. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0048] It should also be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0049] Where there is no conflict, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0050] Example 1

[0051] like Figure 1 As shown, in order to conduct irradiation tests on large quantities of different types of particulate fuel 110, this embodiment provides an embedded sandwich type irradiation test device suitable for fine particulate fuel, including an irradiation device and multiple irradiation test pieces 7.

[0052] The irradiation device has an internal cavity. The irradiation device is equipped with an inlet pipe 1 and an outlet pipe 12 that communicate with the inside of the cavity. Multiple irradiation test pieces 7 are fixedly installed in the cavity of the irradiation device by a fixing assembly. An air gap 6 is provided between the outer side of the irradiation test piece 7 and the inner side of the cavity.

[0053] The irradiation device is placed in the irradiation environment, and a mixed gas is introduced into the cavity through the gas inlet pipe 1. By adjusting the composition of the mixed gas, the thermal resistance of the gas gap 6 can be changed, thereby achieving the purpose of changing the temperature of the irradiated test piece 7, such as changing the volume fraction of argon in the argon / argon gas mixture.

[0054] A helium cavity 113 is provided inside the irradiation test piece 7. Particle fuel 110 is placed inside the helium cavity 113 of the irradiation test piece 7. A gas sampling tube 103 connected to the helium cavity 113 is provided on the irradiation test piece 7.

[0055] The test environment of the particulate fuel 110 is controlled by changing the purpose of the irradiation test piece 7, and the reaction gas in multiple irradiation test pieces 7 is taken out through the gas sampling tube 103. Each irradiation test piece 7 is tested on the particulate fuel 110 through an independent gas sampling tube 103.

[0056] By placing different types of particulate fuel 110 into different irradiation test specimens 7, the purpose of conducting irradiation tests on large quantities of different types of particulate fuel 110 can be achieved.

[0057] Due to the significant differences in axial neutron flux rates within the reactor, the fission power of the particulate fuel 110 within the irradiation test specimen 7 varies considerably at different locations within the irradiation facility. By designing different outer diameters of the irradiation test specimen 7 to alter the thickness of the air gap 6 at corresponding locations, and matching different loading masses of particulate fuel 110, the irradiation test temperatures of the particulate fuel 110 at different axial locations can be flattened.

[0058] Therefore, the thickness of the air gap 6 between the outer surface of the irradiated test piece 7 and the inner surface of the cavity is not equal depending on the requirements.

[0059] Example 2

[0060] This embodiment describes the structure of the irradiation device and the irradiation test specimen 7.

[0061] like Figure 1 As shown, the irradiation device includes an outer tube 3, an upper end cover 2, and a lower end cover 10.

[0062] by Figure 1 The left side is the upper end, and the right side is the lower end. The upper end cover 2 is connected to the upper end of the outer tube 3, and the lower end cover 10 is connected to the lower end of the outer tube 3. The air inlet pipe 1 and the air outlet pipe 12 are connected to the upper end cover 2 or the lower end cover 10 and communicate with the inside of the outer tube 3. The irradiation test piece 7 is placed inside the outer tube 3.

[0063] The outer surfaces of the intake pipe 1 and the exhaust pipe 12 need to be sealed to the upper end cap 2 or the lower end cap 10, so that the mixed gas can only enter from the intake pipe 1 and exit from the exhaust pipe 12. Furthermore, the upper end cap 2 and the lower end cap 10 also need to be sealed after being installed onto the outer casing 3.

[0064] Multiple irradiated test specimens 7 are stacked axially in the accommodating cavity and fixed by a fixing assembly, which includes an upper support 4 and a lower support 9.

[0065] The lower end of the upper support 4 is in contact with the irradiated test specimen 7, and the upper end of the upper support 4 is connected to the lower side of the upper end cover 2; the upper end of the lower support 9 is in contact with the irradiated test specimen 7, and the lower end of the upper support 4 is connected to the upper side of the lower end cover 10.

[0066] The upper support 4 and the lower support 9 exert a clamping force on the irradiated test specimen 7, so that the irradiated test specimen 7 can be fixed inside the outer sleeve 3 and an air gap 6 is maintained between it and the inner wall of the outer sleeve 3.

[0067] In addition, to prevent heat conduction between adjacent irradiated test specimens 7, upper support 4 and lower support 9, an annular heat insulation component 11 is provided between two adjacent irradiated test specimens 7; at the same time, an upper heat insulation plate 5 and a lower heat insulation plate 8 are added. The upper heat insulation plate 5 is located between the lower end of the irradiated test specimen 7 and the upper support 4; the lower heat insulation plate 8 is located between the upper end of the irradiated test specimen 7 and the lower support 9.

[0068] For stability, the upper heat insulation plate 5 can be fixedly connected to the upper support member 4, and the lower heat insulation plate 8 can be fixedly connected to the lower support member 9.

[0069] like Figure 2 As shown, the irradiation test specimen 7 includes an outer tube 101, an inner tube 104, an upper cover plate 102, a lower cover plate 105, and a fuel fixing component, and is arranged in a manner consistent with... Figure 2 The upper side is the top end, and the lower side is the bottom end.

[0070] The outer tube 101 is coaxially arranged inside the outer sleeve 3, and the outer diameter of the outer tube 101 is smaller than the inner diameter of the outer sleeve 3. There is an air gap 6 between the outer surface of the outer tube 101 and the inner surface of the outer sleeve 3.

[0071] The inner tube 104 is coaxially arranged inside the outer tube 101. The cavity between the inner side of the outer tube 101 and the outer side of the inner tube 104 is set as a helium cavity 113. The helium cavity 113 is filled with atmospheric pressure helium. The inner tubes 104 of multiple irradiation test pieces 7 are coaxially installed to form an intermediate channel. The lower end of the inlet pipe 1 is connected to the upper part of this intermediate channel.

[0072] The inner ring of the annular upper cover plate 102 is connected to the upper end of the inner tube 104, and the outer ring of the upper cover plate 102 is connected to the upper end of the outer tube 101; the inner ring of the annular lower cover plate 105 is connected to the lower end of the inner tube 104, and the outer ring of the lower cover plate 105 is connected to the lower end of the outer tube 101.

[0073] After the fuel pellets are installed, the outer tube 101, inner tube 104, upper cover plate 102 and lower cover plate 105 can be fixedly connected by welding.

[0074] The fuel fixing component is located inside the helium cavity 113, and the fuel fixing component has a placement cavity, in which the particulate fuel 110 is fixed; the placement cavity is connected to the helium cavity 113, and the helium cavity 113 is connected to the gas sampling tube 103.

[0075] The particulate fuel 110 is fixed in the placement cavity. The gas produced by the fission of the particulate fuel 110 flows to the helium cavity 113 and is taken out for testing through the gas sampling tube 103, thus achieving the purpose of the irradiation test.

[0076] To secure the particulate fuel 110, the fuel securing component includes a lower plate 108, an upper plate 111, and a soft metal layer 109.

[0077] The lower side of the annular lower plate 108 is tightly fitted to the lower cover plate 105, the outer side of the lower plate 108 is fitted to the inner side of the outer tube 101, the upper side of the lower plate 108 is provided with an annular groove, and the inner side of the lower plate 108 is provided with a ventilation notch 112 connecting the annular groove and the helium cavity 113; the lower side of the annular upper plate 111 is fitted to the upper side of the lower plate 108, and the outer side of the upper plate 111 is fitted to the inner side of the outer tube 101; a gap is provided between the inner side of the lower plate 108 and the inner side of the upper plate 111 and the outer side of the inner tube 104.

[0078] The ventilation opening 112 facilitates the introduction of fission gas released from the particulate fuel 110 into the helium cavity 113 of the irradiated test specimen 7.

[0079] The annular groove and the upper plate 111 form a placement cavity. In order to fix the particulate fuel 110, the soft metal layer 109 is laid flat in the annular groove, and the particulate fuel 110 is embedded in the soft metal layer 109.

[0080] In this embodiment, the lower plate 108 can be integrally formed with the outer tube 101, so there is no contact gap between the outer tube 101 and the outer side wall of the lower plate 108.

[0081] By utilizing the tight fit between the upper plate 111 and the lower plate 108, a portion of the fuel particles is squeezed and embedded into the soft metal layer 109, thereby ensuring a tight fit between the lower part of the fuel particles 110 and the soft metal layer 109.

[0082] In order to achieve a uniform distribution of multiple fuel pellets 110, the depth of the annular groove is greater than the diameter of the fuel pellets 110, the thickness of the soft metal layer 109 is less than the diameter of the fuel pellets 110, and when the fuel pellets 110 are embedded in the soft metal layer 109, the fuel pellets 110 are tangent to the lower side of the upper plate 111.

[0083] In practice, based on the average diameter and deviation range of the pellet fuel 110, the depth of the annular groove and the thickness of the soft metal layer 109 are precisely designed. Simultaneously, the number of pellet fuel 110 particles on the soft metal layer 109 is accurately controlled, thus ensuring that there is only a single layer of pellet fuel 110 between the upper plate 111 and the lower plate 108, and that all pellet fuel 110 particles are partially embedded in the thin metal layer. The fission heat generated by the pellet fuel 110 during the irradiation test is conducted out through the contact heat conduction between the pellet fuel 110 and the soft metal layer 109, and then sequentially through the soft metal layer 109, the lower plate 108, the outer tube 101, the air gap 6, and the outer jacket 3, finally being carried away by the cooling water outside the irradiation device.

[0084] In order to indirectly detect the temperature of the particulate fuel 110, the irradiation test piece 7 also includes an inner thermocouple 106 and an outer thermocouple 107. Both the inner thermocouple 106 and the outer thermocouple 107 are used to measure the temperature of the lower plate 108, and the distance between the measuring point of the inner thermocouple 106 and the inner surface of the lower plate 108 is smaller than the distance between the measuring point of the outer thermocouple 107 and the inner surface of the lower plate 108.

[0085] The probes of an outer thermocouple 107 and an inner thermocouple 106 are respectively installed on the radially outer and radially inner sides of the lower surface of the lower plate 108. The temperature of the particulate fuel 110 can be indirectly monitored through the inner thermocouple 106 to prevent the particulate fuel 110 from melting due to overheating during the test. At the same time, by measuring the radial temperature difference of the lower plate 108 through the outer thermocouple 107 and the inner thermocouple 106, it can be used to indirectly measure the fission heat release power of the particulate fuel 110 in the irradiated test specimen 7.

[0086] The structural materials of the irradiation device and the irradiation test specimen 7 are both made of aluminum alloy. The soft metal layer 109 is made of gold. The annular heat insulation component 11, the upper heat insulation plate 5, and the lower heat insulation plate 8 are made of ceramic material.

[0087] To facilitate the exit of the gas sampling tube 103 and the signal lead 13, the outer tube 3, outer tube 101, inner tube 104 and inlet tube 1 are all coaxially arranged; the gas sampling tube 103 is located inside the inner tube 104 and passes through the inner tube 104 to communicate with the helium cavity 113; the signal lead 13 of the outer thermocouple 107, the signal lead 13 of the inner thermocouple 106 and the gas sampling tube 103 are all located outside the irradiation test device through the inner tube 104 and the inlet tube 1.

[0088] This embodiment uses an embedded sandwich scheme to encapsulate the pellet fuel 110. Through the reliable embedding and good contact between the single-layer pellet fuel 110 and the soft metal layer 109, the heat transfer between the soft metal with high thermal conductivity and the pellet fuel 110 is utilized to efficiently extract the fission heat release of the fuel, thereby ensuring the test safety of the pellet fuel 110.

[0089] By designing different outer diameters of the irradiation test specimen 7 and matching them with different loading masses of particulate fuel 110, the temperature distribution of particulate fuel 110 at different axial positions can be flattened, and the temperature of particulate fuel 110 during the irradiation test can be adjusted and controlled by the gas composition orifice of the air gap 6.

[0090] By setting temperature measuring points of thermocouples for each irradiated test piece 7, the temperature of the particulate fuel 110 is indirectly monitored to prevent the particulate fuel 110 from melting due to overheating during the test; by measuring the radial temperature difference of the lower plate 108 of the irradiated test piece 7, the fission heat release power of the particulate fuel 110 in the irradiated test piece 7 can be calculated.

[0091] A gas sampling tube 103 is designed for each irradiated test specimen 7, thereby establishing an online gas sampling channel for each irradiated test specimen 7.

[0092] Example 3

[0093] This embodiment provides a specific example.

[0094] For particulate fuel 110 with a particle size of 0.14±0.02mm, the upper part of the lower plate 108 is provided with an annular groove with a depth of 0.2mm, and a soft metal layer 109 with a thickness of 0.1mm is placed in the annular groove.

[0095] Fuel pellets are evenly spread on a soft gold foil and pressed down by an upper plate 111, causing the fuel pellets 110 to embed into the soft gold foil. Fuel pellets 110 of different sizes are tangential to the surface of the upper plate 111 and are embedded into the gold foil at different depths.

[0096] Since the particulate fuel 110 is in point contact with the upper plate 111, and there is a gap between the lower plate 108 and the upper plate 111, as well as gaps between each fuel particle, the release of the fuel's own fission gas is not hindered.

[0097] The lower part of the fuel pellets is in close contact with the soft metal layer 109, and its temperature is reduced through heat conduction between the soft metal layer 109 and the lower plate 108. The heat released by the pellet fuel 110 is transferred to the outer tube 101 of the irradiation test specimen 7 through radial heat conduction, and then to the core cooling water through the air gap 6 and the outer sleeve 3. The temperature of the outer tube 101 of the irradiation test specimen 7 can be adjusted by the temperature control principle of the air gap 6, thereby indirectly achieving temperature control of the pellet fuel 110.

[0098] Since the heat conduction between the pellet fuel 110 and the upper clamping plate can be ignored, the heat release of the pellet fuel 110 is input into a uniform heat flux density on the annular surface of the lower plate 108 projected onto it. This heat flux density can then be approximated as the internal heat source of this annular structure. Therefore, an annular heat conduction model with an internal heat source is used to solve for the temperature difference between the inner and outer sides of this annular structure, and finally, the temperature difference range of the pellet fuel 110 at different radial positions is estimated.

[0099] If the outer and inner radii of the soft metal layer 109 are 25 mm and 7 mm respectively, then the area of ​​the annular thin layer is 1810 mm². 2 The sparseness of the particulate fuel 110 on the gold foil is represented by a coefficient C, where C is the proportion of the total projected area of ​​all particulate fuel 110 outlines to the total area of ​​the gold foil. If the average gap between particles is 40% of the particle diameter, then C is 54.5% for all particle sizes. Taking the gamma heat release rate of the aluminum alloy as 4.5 W / g, the internal heat source of the lower clamping ring structure projected by the particulate fuel 110 region is 1.03E+8 W / m.3 The temperature difference between the inner and outer sides of the annular structure is 64.2℃. This means that the temperature difference between different particulate fuels 110 within the annular region is also approximately equal to this value, indicating that the irradiation temperature uniformity of the particulate fuels 110 is relatively good.

[0100] The temperature inside the lower plate 108 is measured in real time using the thermocouple 106 on the inner side of the lower plate 108; the temperature difference data between the pellet fuel 110 and the corresponding position of the lower plate 108 is used to indirectly monitor the irradiation temperature of the pellet fuel 110, preventing the fuel from melting due to excessive temperature; the fission heat release power of the pellet fuel 110 inside the irradiation test piece 7 is calculated by measuring the radial temperature difference of the lower plate 108 of the irradiation test piece 7.

[0101] The fission gas released by the pellet fuel 110 can enter the helium cavity 113 of the irradiated test piece 7 through the ventilation opening 112 on the inner side of the lower plate 108. The gas sampling tube 103 of the irradiated test piece 7 can be used to realize online monitoring and measurement of the gas inside the test piece.

[0102] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0103] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0104] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. An irradiation test device of the mosaic sandwich type suitable for use with fine particle fuel, characterized in that, The utility model relates to a kind of irradiation device and irradiation test piece, including: Radiation device, which is internally provided with accommodating cavity, the radiation device is provided with gas inlet pipe (1) and gas outlet pipe (12) that communicate with the inside of the accommodating cavity; A plurality of irradiation test pieces (7) are fixedly arranged in the accommodating cavity of the radiation device by a fixing assembly, and the irradiation test piece (7) is internally provided with a helium cavity (113). An air gap (6) is provided between the outer side of the irradiation test piece (7) and the inner side of the accommodating cavity. The helium cavity (113) of the irradiation test piece (7) is placed with a granular fuel (110). The irradiation test piece (7) is provided with a gas sampling pipe (103) that communicates with the helium cavity (113). Each of the irradiation test pieces (7) includes: A fuel fixing member is arranged in the helium cavity (113) for fixing the granular fuel (110). The fuel fixing member includes: An annular lower plate (108) having an annular groove on its upper side; A soft metal layer (109) laid in the annular groove; An annular upper plate (111) having a lower side that is attached to the upper side of the lower plate (108) to inlay and fix the granular fuel (110) into the soft metal layer (109).

2. The mosaic sandwich type irradiation test device for fine particle type fuel according to claim 1, characterized by The thickness of the air gap (6) between the outer side of different irradiation test pieces (7) and the inner side of the accommodating cavity is not equal.

3. The mosaic sandwich type irradiation test device for fine particle type fuel according to claim 2, characterized by The radiation device includes: An outer sleeve (3); An upper end cover (2) connected to the upper end of the outer sleeve (3); A lower end cover (10) connected to the lower end of the outer sleeve (3); The gas inlet pipe (1) and the gas outlet pipe (12) are connected to the upper end cover (2) or the lower end cover (10) and communicate with the inside of the outer sleeve (3). The irradiation test pieces (7) are arranged in the outer sleeve (3).

4. The mosaic sandwich type irradiation test device for fine particle type fuel according to claim 3, characterized by A plurality of irradiation test pieces (7) are axially stacked in the accommodating cavity. The fixing assembly includes: An upper support (4) having a lower end in contact with the irradiation test piece (7) and an upper end connected to the lower side of the upper end cover (2); A lower support (9) having an upper end in contact with the irradiation test piece (7) and a lower end connected to the upper side of the lower end cover (10).

5. The mosaic sandwich type irradiation test device for fine particle type fuel according to claim 4, characterized by An annular heat insulating member (11) is arranged between two adjacent irradiation test pieces (7). The fixing assembly further includes: An upper heat insulating plate (5) arranged between the irradiation test piece (7) and the lower end of the upper support (4); A lower heat insulating plate (8) arranged between the irradiation test piece (7) and the upper end of the lower support (9).

6. A mosaic sandwich type irradiation test device suitable for use with fine particle type fuel according to claim 3, 4 or 5, characterized in that, The irradiation test piece (7) includes: An outer tube (101) coaxially arranged in the outer sleeve (3), and the outer diameter of the outer tube (101) is smaller than the inner diameter of the outer sleeve (3); An inner tube (104) coaxially arranged inside the outer tube (101). The cavity between the inner side of the outer tube (101) and the outer side of the inner tube (104) is arranged as the helium cavity (113). An annular upper cover plate (102) is connected with the upper end of the inner tube (104) at its inner ring and connected with the upper end of the outer tube (101) at its outer ring; An annular lower cover plate (105) is connected with the lower end of the inner tube (104) at its inner ring and connected with the lower end of the outer tube (101) at its outer ring; The fuel fixing member is provided with a placing cavity, and the granular fuel (110) is fixed in the placing cavity; The placing cavity is communicated with the helium cavity (113), and the helium cavity (113) is communicated with the gas sampling tube (103).

7. The mosaic sandwich type irradiation test device for fine particle type fuel according to claim 6, characterized by The lower side of the lower plate (108) is tightly attached to the lower cover plate (105), the outer side of the lower plate (108) is attached to the inner side of the outer tube (101), the inner side of the lower plate (108) is provided with a ventilation gap (112) which communicates the annular groove and the helium cavity (113), the outer side of the upper plate (111) is attached to the inner side of the outer tube (101), and the granular fuel (110) is inlaid into the soft metal layer (109).

8. The mosaic sandwich type irradiation test device for fine particle type fuel according to claim 7, characterized by The depth of the annular groove is greater than the diameter of the granular fuel (110), the thickness of the soft metal layer (109) is less than the diameter of the granular fuel (110), and the granular fuel (110) is tangent to the lower side of the upper plate (111); The inner side of the lower plate (108) and the inner side of the upper plate (111) are provided with a gap between the outer side of the inner tube (104).

9. The mosaic sandwich type irradiation test device for fine particulate fuel according to claim 7, wherein The irradiation test piece (7) further comprises an inner side thermocouple (106) and an outer side thermocouple (107), both of which are used for measuring the temperature of the lower plate (108), and the distance between the measuring point of the inner side thermocouple (106) and the inner side of the lower plate (108) is less than the distance between the measuring point of the outer side thermocouple (107) and the inner side of the lower plate (108).

10. The mosaic sandwich type irradiation test device for fine particulate fuel according to claim 9, wherein The outer sleeve (3), the outer tube (101), the inner tube (104) and the gas inlet tube (1) are coaxially arranged; The gas sampling tube (103) is arranged in the inner tube (104) and communicated with the helium cavity (113) through the inner tube (104); The signal lead wire (13) of the outer side thermocouple (107), the signal lead wire (13) of the inner side thermocouple (106) and the gas sampling tube (103) are all arranged outside the irradiation test device through the inner tube (104) and the gas inlet tube (1).

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