An apparatus and method for studying the diffusion of radionuclides in barrier materials

Abstract

This invention belongs to the field of high-level radioactive waste treatment technology, specifically relating to an apparatus and method for studying the diffusion of radionuclides in barrier materials. The apparatus includes a sample holding unit, a first fluid circulation unit, a second fluid circulation unit, and a fluid circulation drive unit. The sample holding unit is used to fix the barrier material sample, and its end caps are detachably sealed. The first and second fluid circulation units each include a water tank disposed inside the end caps and connected inlet and outlet holes. The water tank has two interchangeable structural forms: a concave water tank and a spiral channel. The fluid circulation drive unit is used to drive the fluid to circulate independently within the two water tanks to maintain a constant concentration. By changing the water tank structure, this apparatus can use a concave water tank to adapt to rigid monolithic media, or a spiral channel combined with a porous filter membrane to adapt to soft powder media, thereby achieving complete diffusion simulation of various barrier materials in the disposal repository.

Description

Technical Field

[0001] This invention belongs to the field of high-level radioactive waste treatment technology, specifically relating to an apparatus and method for studying the diffusion of radionuclides in barrier materials. Background Technology

[0002] Deep geological disposal of high-level radioactive waste (HDW) is currently the internationally recognized safe disposal method. It relies on a multi-barrier system consisting of engineering barriers (such as concrete and bentonite) and natural barriers (such as granite) to isolate radionuclides in the long term. In this system, groundwater is the main carrier of nuclide migration. Therefore, to assess its long-term safety, it is necessary to accurately simulate the diffusion behavior of nuclides in various barrier materials in the laboratory.

[0003] Currently, existing diffusion experimental devices mainly employ a fixed-volume diffusion cell structure. The sample to be studied is placed inside the diffusion cell, using the sample itself as an isolation structure. A source solution containing radionuclides and a background solution are added to one side of the sample. The diffusion parameters of the barrier material are then inferred by monitoring the change in radionuclide concentration in the receiving solution over time. However, this type of diffusion device can only simulate rigid barrier materials such as rock flakes and compacted clay columns, exhibiting poor compatibility. In particular, it is difficult to adapt to the diffusion of radionuclides in barrier materials such as bentonite, natural clay, and granite powder. The simulation conditions have low consistency with real disposal environments, making it difficult to comprehensively and accurately simulate the diffusion behavior of radionuclides in various barrier materials in high-level waste repositories. This results in a significant discrepancy between the experimental data obtained and the radionuclide migration behavior under real disposal environments, thus limiting the reliability of safety assessments.

[0004] Therefore, there is an urgent need for an experimental device and method that can more realistically, reliably, and comprehensively simulate the diffusion behavior of nuclides in deep geological repositories. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide an apparatus and method for studying the diffusion of radionuclides in barrier materials. This method can comprehensively and accurately simulate the diffusion behavior of radionuclides in various barrier materials in high-level radioactive waste repositories, improving the accuracy between experimental data and nuclide migration behavior under real disposal environments, and providing a reliable basis for the safety assessment of deep geological disposal of high-level radioactive waste.

[0006] The technical solution of this invention is: An apparatus for studying the diffusion of radionuclides in barrier materials, comprising: The sample clamping unit includes a tube for accommodating and fixing a barrier material sample, and a first end cap and a second end cap that are detachably and sealed to both ends of the tube. Porous filter membranes are respectively provided on the side of the first end cap and the second end cap facing the tube. The first end cap and the second end cap are connected to the tube to press the two porous filter membranes together on both sides of the sample while pressing the sample along the axial direction of the tube. The fluid circulation unit includes a first water tank and a second water tank respectively disposed in a first end cap and a second end cap, and the openings of the first water tank and the second water tank both face the pipe body. The first water tank is provided with a first water inlet and a first water outlet, and the second water tank is provided with a second water inlet and a second water outlet. The fluid circulation drive unit has two independent transmission channels. The inlet and outlet of one transmission channel are respectively connected to the first water inlet and the first water outlet, and the inlet and outlet of the other transmission channel are respectively connected to the second water inlet and the second water outlet. It is used to drive the fluid to circulate independently in the first water tank and the second water tank to maintain a constant concentration of radionuclides in the fluid flowing through both sides of the sample. The first and second water tanks are used to inject a background solution and a solution containing a tracer nuclide. The first and second water tanks are used interchangeably with at least two structural forms: a concave water tank or a spiral water channel with a spiral cross-section, to accommodate different barrier material samples.

[0007] Preferably, the pipe body has internal threads at both ends, and the first end cap and the second end cap each include a cover plate and an external threaded post fixed to the cover plate. The external threaded post has a hollow structure and is adapted to the internal threads on the pipe body. The first water tank and the second water tank are respectively disposed in the corresponding external threaded post, and the first end cap and the second end cap are provided with a sealing assembly between them and the pipe body to achieve sealing between the first end cap and the pipe body after the first end cap and the second end cap are screwed together.

[0008] Preferably, the sealing assembly includes at least one O-ring made of elastic material, which is fitted onto the external threaded post.

[0009] Preferably, the sealing assembly further includes one or more gaskets made of elastic material, the gaskets being placed on the side of the external threaded cylinder facing the tube body. After the first end cap and the second end cap are screwed onto the tube body, they are used to compress the sample while forming a secondary seal with the tube body by squeezing the gaskets at both ends.

[0010] Preferably, the tube body, the first end cap, and the second end cap are all made of transparent material.

[0011] Preferably, the first water tank and the second water tank are the same size and structure.

[0012] Preferably, the fluid circulation drive unit includes at least one dual-channel peristaltic pump. The dual-channel peristaltic pump has two transmission channels. The inlet end of one transmission channel is connected to the first outlet via a fluid pipe, and the outlet end is connected to the first inlet via a fluid pipe. The inlet end of the other transmission channel is connected to the second outlet via a fluid pipe, and the outlet end is connected to the second inlet via a fluid pipe. This allows it to form independent circulation loops with the first water tank and the second water tank, respectively.

[0013] Preferably, a method for studying the diffusion of radionuclides in barrier materials, implemented using any of the above-described experimental apparatus, includes the following steps: S1: Place the rigid barrier material sample inside the tube; S2: Select a first water tank and a second water tank with a concave water tank or a spiral water channel structure, place the first water tank on the first end cap, place the second water tank on the second end cap, and seal the first end cap and the second end cap on both sides of the tube body to press the sample in the tube body along the axial direction of the tube body. S3: Connect the fluid circulation drive unit to the first water inlet, the first water outlet, the second water inlet, and the second water outlet respectively, so that the first water tank and the second water tank form independent circulation loops respectively; S4: Inject a solution containing a tracer nuclide into the first water tank, and inject a background solution into the second water tank; S5: Start the fluid circulation drive unit to make the solution circulate independently in the first water tank and the second water tank respectively; S6: During the experimental period, samples are periodically taken from the second water tank, and the concentration changes of the tracer nuclides are detected to study the diffusion behavior of the radionuclides in the rigid barrier material.

[0014] Preferably, a method for studying the diffusion of radionuclides in barrier materials, implemented using any of the above-described experimental apparatus, includes the following steps: S1: Place the soft barrier material sample inside the tube, and attach one or more porous filter membranes to both sides of the sample. S2: Select the first water tank and the second water tank with the structure of spiral water channel, set the first water tank on the first end cap, set the second water tank on the second end cap, and seal the first end cap and the second end cap on both sides of the tube body. Through the connection of the first end cap and the second end cap, the porous filter membrane on both sides is squeezed and adhered to both sides of the sample and the sample is pressed along the axial direction of the tube body. S3: Connect the fluid circulation drive unit to the first water inlet, the first water outlet, the second water inlet, and the second water outlet respectively, so that the first water tank and the second water tank form independent circulation loops respectively; S4: Inject a solution containing tracer nuclides into the first water tank of the spiral water channel structure, and inject a background solution into the second water tank of the spiral water channel structure; S5: Start the fluid circulation drive unit to make the solution circulate independently in the first water tank and the second water tank respectively; S6: During the experimental period, samples are periodically taken from the spiral channel of the second end cap, and the concentration change data of the tracer nuclide therein are detected to study the diffusion behavior of the radionuclide in the soft powder barrier material.

[0015] Compared with the prior art, the apparatus and method of the present invention for studying the diffusion of radionuclides in barrier materials have the following advantages: This invention effectively simulates the real environment in deep geological treatment reservoirs where groundwater can infiltrate from both sides of a barrier material by setting up a sample clamping unit and two independently circulating first and second fluid circulation units located on both sides of the sample. Specifically, by designing the first and second water tanks to include at least two interchangeable structural forms—a concave water tank and a spiral waterway—the same device can be compatible with diffusion experiments on both rigid and soft powder media. The spiral waterway, in conjunction with a porous filter membrane, prevents the soft media from swelling, clogging, or dissolving, thus solving the problems of poor compatibility and inability to comprehensively simulate multiple media in existing technologies. The system addresses the issues of heavy-barrier systems. Simultaneously, by utilizing a fluid circulation drive unit to independently and continuously circulate the solutions in the two side tanks, it maintains relative stability of the solution concentrations at the diffusion source and receiving end during the experiment. This better suits the actual conditions of large volume and high nuclide concentration in high-level radioactive waste repositories, overcoming the concentration drop problem caused by limited solution in traditional static diffusion pools. It comprehensively and accurately simulates the diffusion behavior of radionuclides in various barrier materials within high-level radioactive waste repositories, improving the accuracy between experimental data and nuclide migration behavior under real disposal conditions, and providing a reliable basis for the safety assessment of deep geological disposal of high-level radioactive waste. Attached Figure Description

[0016] Figure 1 This is an assembly diagram of the overall structure of the device in an embodiment of the present invention; Figure 2 This is a schematic diagram of the overall structure of the device in an embodiment of the present invention; Figure 3 This is an exploded view of the structural assembly of the soft barrier material in an embodiment of the present invention; Figure 4This is an exploded view of the partial structural assembly of the rigid barrier material in an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Tube body; 2. First end cap; 3. Second end cap; 4. Porous filter membrane; 5. First water tank; 6. Second water tank; 7. Cover plate; 8. External threaded post; 9. O-ring seal; 10. Washer; 11. Barrier material; 12. Internal thread; 13. Peristaltic pump. Detailed Implementation

[0018] 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 merely illustrative and not intended to limit the invention.

[0019] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0020] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0021] See Figures 1 to 4 As shown, in order to comprehensively and accurately simulate the diffusion behavior of radionuclides in various barrier materials 11 in high-level radioactive waste repositories, improve the accuracy between experimental data and nuclide migration behavior under real disposal environments, and provide a reliable basis for the safety assessment of deep geological disposal of high-level radioactive waste, this embodiment provides an apparatus for studying the diffusion of radionuclides in barrier materials, including: a sample clamping unit, a fluid circulation unit, and a fluid circulation drive unit.

[0022] Among them, see Figure 1 and Figure 3As shown, the sample clamping unit includes a tube 1 for accommodating and fixing the barrier material 11 sample, and a first end cap 2 and a second end cap 3 detachably and sealingly connected to both ends of the tube 1. The tube 1, the first end cap 2, and the second end cap 3 are all made of transparent material. Porous filter membranes 4 are respectively provided on the side of the first end cap 2 and the second end cap 3 facing the tube 1. The first end cap 2 and the second end cap 3 are connected to the tube 1 by threads, so that the two porous filter membranes 4 are pressed and adhered to both sides of the sample while simultaneously pressing the sample along the axial direction of the tube 1. Specifically, internal threads 12 are provided at both ends of the tube 1, and the first end cap 2 and the second end cap 3 are each composed of a cover plate 7 and an externally threaded post 8 fixed to the cover plate 7. The cover plate 7 and the externally threaded post 8 are fixed by bolts. The externally threaded post 8 has a hollow structure and is adapted to the internal threads 12 on the tube 1. A sealing assembly is provided between the first end cap 2 and the second end cap 3 and the tube 1 to achieve a seal between the first end cap 2 and the second end cap 3 and the tube 1 after screwing them together. In order to ensure the sealing of the experiment, the porous filter membrane 4 is generally made of rigid materials, such as polyethersulfone (PES), mixed cellulose ester, polytetrafluoroethylene, etc.

[0023] See Figure 2 and Figure 4 As shown, the fluid circulation unit includes a first water tank 5 and a second water tank 6 respectively disposed within the first end cap 2 and the second end cap 3, with the openings of both the first water tank 5 and the second water tank 6 facing the pipe body 1. The first water tank 5 is provided with a first water inlet and a first water outlet, and the second water tank 6 is provided with a second water inlet and a second water outlet. Specifically, the first water tank 5 and the second water tank 6 are respectively disposed within corresponding externally threaded columns 8, and the first water tank 5 and the second water tank 6 are the same in size and structure. The first water tank 5 and the second water tank 6 can be used interchangeably with at least two structural forms: a concave water tank or a spiral water channel with a spiral cross-section, to adapt to the testing of different barrier material 11 samples. When the first water tank 5 and the second water tank 6 are concave water tank structures, they can be directly formed within the hollow cavity of the externally threaded column 8, or a tank body adapted to the hollow cavity of the externally threaded column 8 can be provided. When the first water tank 5 and the second water tank 6 adopt a spiral water channel structure with a spiral cross-section, the spiral water channel abuts against the porous filter membrane 4 during installation, forming a unidirectional flow channel, with one end being the inlet and the other end being the outlet. In the experiment, one of the first water tank 5 and the second water tank 6 is used to inject the background solution (groundwater), and the other is used to inject the solution containing the tracer nuclide.

[0024] See Figure 1 and Figure 2As shown, the fluid circulation drive unit has two independent transmission channels. The inlet and outlet of one transmission channel are connected to the first inlet and the first outlet, respectively, while the inlet and outlet of the other transmission channel are connected to the second inlet and the second outlet, respectively. This drives the fluid to circulate independently within the first water tank 5 and the second water tank 6, maintaining a constant concentration of radionuclides in the fluid flowing across both sides of the sample. Preferably, the fluid circulation drive unit includes at least one dual-channel peristaltic pump 13. The dual-channel peristaltic pump 13 has two independent transmission channels. The inlet of one transmission channel is connected to the first outlet via a fluid pipe, and the outlet is connected to the first inlet via a fluid pipe. The inlet of the other transmission channel is connected to the second outlet via a fluid pipe, and the outlet is connected to the second inlet via a fluid pipe. This forms independent circulation loops with the first water tank 5 and the second water tank 6, respectively. Alternatively, the fluid circulation drive unit can consist of two independent single-channel peristaltic pumps 13, each corresponding to one of the first water tank 5 and the second water tank 6, for independent circulation of the solutions within the first water tank 5 and the second water tank 6.

[0025] See Figure 3 and Figure 4 As shown, furthermore, the sealing assembly includes at least one O-ring 9 made of elastic material, which is fitted onto the externally threaded post 8. To improve the sealing performance of the experiment and ensure more accurate experimental data, the sealing assembly also includes one or more gaskets 10 made of elastic material. The gaskets 10 are placed on the side of the externally threaded post 8 facing the tube body 1. After the first end cap 2 and the second end cap 3 are screwed onto the tube body 1, they are used to compress the sample through the gaskets 10 at both ends, while simultaneously forming a secondary seal between the sample and the tube body 1. Preferably, both the O-ring 9 and the gaskets 10 are made of rubber or silicone.

[0026] Based on the structural design of the above-mentioned device, the present invention includes at least the following two experimental methods to accurately simulate the diffusion behavior of radionuclides in various barrier materials 11 in high-level radioactive waste disposal repositories, thereby improving the accuracy between experimental data and nuclide migration behavior under real disposal conditions.

[0027] Method 1: A method for studying the diffusion of radionuclides in a rigid barrier material 11 includes the following steps: S1: Place the rigid barrier material 11 sample inside the tube 1, and select a porous filter membrane 4 based on the shape of the rigid barrier material 11 sample. Specifically, when the rigid barrier material 11 sample is a regular column that fits the tube 1, such as a compacted clay column or a drilled rock column, a porous filter membrane 4 is not required; when the rigid barrier material 11 sample has an irregular structure, such as a rock block, at least one porous filter membrane 4 is recommended.

[0028] S2: Select a first water tank 5 and a second water tank 6 with a concave water tank or a spiral water channel structure. Place the first water tank 5 on the first end cap 2 and the second water tank 6 on the second end cap 3. Seal the first end cap 2 and the second end cap 3 on both sides of the tube body 1 through a sealing assembly. Press the sample in the tube body 1 along the axial direction of the tube body 1.

[0029] S3: Connect the fluid circulation drive unit to the first water inlet, the first water outlet, the second water inlet and the second water outlet respectively, so that the first water tank 5 and the second water tank 6 form independent circulation loops respectively; S4: Inject a solution containing tracer nuclides into the first water tank 5, and inject a background solution into the second water tank 6. The background solution is groundwater. S5: Start the fluid circulation drive unit to make the solution circulate independently in the first water tank 5 and the second water tank 6 respectively; S6: Set an experimental period (more than 5 days), and take samples from the second water tank 6 periodically during the experimental period to detect the concentration change data of the tracer nuclides in order to study the diffusion behavior of radionuclides in the rigid barrier material 11.

[0030] Method 2: A method for studying the diffusion of radionuclides in a soft barrier material 11, implemented using an experimental setup, includes the following steps: S1: Place the soft barrier material 11 sample (such as bentonite, natural clay and granite powder) inside the tube 1, and attach one or more porous filter membranes 4 to both sides of the sample. The number of porous filter membranes 4 is selected according to the experimental requirements of the soft barrier material 11 sample to ensure that the soft barrier material 11 sample will not dissolve in large quantities during the test, and will not block the flow of the solution or dissolve into the corresponding solution.

[0031] S2: Select the first water tank 5 and the second water tank 6 with the structure of spiral water channel, set the first water tank 5 on the first end cap 2, set the second water tank 6 on the second end cap 3, and seal the first end cap 2 and the second end cap 3 on both sides of the tube body 1. Through the connection of the first end cap 2 and the second end cap 3, the porous filter membrane 4 on both sides is squeezed and adhered to both sides of the sample and the sample is pressed along the axial direction of the tube body 1.

[0032] S3: Connect the fluid circulation drive unit to the first water inlet, the first water outlet, the second water inlet and the second water outlet respectively, so that the first water tank 5 and the second water tank 6 form independent circulation loops respectively; S4: Inject a solution containing tracer nuclides into the first water tank 5 of the spiral water channel structure, and inject a background solution into the second water tank 6 of the spiral water channel structure.

[0033] S5: Start the fluid circulation drive unit to make the solution circulate independently in the first water tank 5 and the second water tank 6 respectively; S6: Set an experimental period (more than 5 days), and during the experimental period, periodically take samples from the spiral channel of the second end cap 3 to detect the concentration change data of the tracer nuclide in order to study the diffusion behavior of radionuclides in the soft powder barrier material 11.

[0034] In summary, the device of this invention, by setting up a sample clamping unit and a first fluid circulation unit and a second fluid circulation unit located on both sides of the sample and circulating independently, effectively simulates the real environment in which groundwater can seep into the barrier material 11 from both sides in a deep geological treatment reservoir. In particular, by designing the first water tank 5 and the second water tank 6 to include at least two interchangeable structural forms, namely a "concave water tank" and a "spiral waterway," the same device can be compatible with diffusion experiments of hard media (such as intact granite, concrete, or compacted clay columns) and soft powder media (such as bentonite and natural clay). The spiral waterway, in conjunction with the porous filter membrane 4, can prevent the soft media from swelling, clogging, or dissolving, thereby solving the problems of poor compatibility and inability to comprehensively address the limitations of existing devices. This system simulates the problems of multi-barrier systems. Simultaneously, by using a fluid circulation drive unit (such as a dual-channel peristaltic pump 13) to drive the solution in both side tanks to circulate independently and continuously, it can maintain a relatively stable solution concentration at the diffusion source and receiving end during the experiment. This better suits the actual conditions of a large high-level radioactive waste repository with high nuclide concentrations, overcoming the concentration drop problem caused by the limited solution in traditional static diffusion tanks. Furthermore, the use of threaded connections and sealing components (such as O-rings 9 and gaskets 10) for compression sealing replaces the traditional multi-screw flange fixing. This not only simplifies the structure, reduces weight, and facilitates operation, but also effectively solves the problem of poor sealing and leakage caused by uneven torque of multiple screws, improving the reliability of long-term diffusion experiments.

[0035] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An apparatus for studying the diffusion of radionuclides in barrier materials, characterized in that, include: The sample clamping unit includes a tube for accommodating and fixing a barrier material sample, and a first end cap and a second end cap that are detachably and sealed to both ends of the tube. Porous filter membranes are respectively provided on the side of the first end cap and the second end cap facing the tube. The first end cap and the second end cap are connected to the tube to press the two porous filter membranes together on both sides of the sample while pressing the sample along the axial direction of the tube. The fluid circulation unit includes a first water tank and a second water tank respectively disposed in a first end cap and a second end cap, and the openings of the first water tank and the second water tank both face the pipe body. The first water tank is provided with a first water inlet and a first water outlet, and the second water tank is provided with a second water inlet and a second water outlet. The fluid circulation drive unit has two independent transmission channels. The inlet and outlet of one transmission channel are respectively connected to the first water inlet and the first water outlet, and the inlet and outlet of the other transmission channel are respectively connected to the second water inlet and the second water outlet. It is used to drive the fluid to circulate independently in the first water tank and the second water tank to maintain a constant concentration of radionuclides in the fluid flowing through both sides of the sample. The first and second water tanks are used to inject a background solution and a solution containing a tracer nuclide. The first and second water tanks are used interchangeably with at least two structural forms: a concave water tank or a spiral water channel with a spiral cross-section, to accommodate experiments with different barrier material samples.

2. The apparatus for studying the diffusion of radionuclides in barrier materials according to claim 1, characterized in that, The tube body has internal threads at both ends. The first end cap and the second end cap each include a cover plate and an external threaded post fixed to the cover plate. The external threaded post is a hollow structure and is adapted to the internal threads on the tube body. The first water tank and the second water tank are respectively disposed in the corresponding external threaded post. Furthermore, the first end cap and the second end cap are provided with a sealing assembly between themselves and the tube body to achieve a seal between themselves and the tube body after the first end cap and the second end cap are screwed together.

3. The apparatus for studying the diffusion of radionuclides in barrier materials according to claim 2, characterized in that, The sealing assembly includes at least one O-ring made of elastic material, which is fitted onto the externally threaded post.

4. The apparatus for studying the diffusion of radionuclides in barrier materials according to claim 3, characterized in that, The sealing assembly also includes one or more gaskets made of elastic material. The gaskets are placed on the side of the external threaded cylinder facing the tube body. After the first end cap and the second end cap are screwed onto the tube body, they are used to compress the sample and form a secondary seal with the tube body by squeezing the gaskets at both ends.

5. The apparatus for studying the diffusion of radionuclides in barrier materials according to claim 1, characterized in that, The tube body, the first end cap, and the second end cap are all made of transparent material.

6. The apparatus for studying the diffusion of radionuclides in barrier materials according to claim 1, characterized in that, The first water tank and the second water tank are the same size and structure.

7. The apparatus for studying the diffusion of radionuclides in barrier materials according to claim 1, characterized in that, The fluid circulation drive unit includes at least one dual-channel peristaltic pump. The dual-channel peristaltic pump has two transmission channels. The inlet end of one transmission channel is connected to the first outlet through a fluid pipe, and the outlet end is connected to the first inlet through a fluid pipe. The inlet end of the other transmission channel is connected to the second outlet through a fluid pipe, and the outlet end is connected to the second inlet through a fluid pipe. This is used to form independent circulation loops with the first water tank and the second water tank, respectively.

8. A method for studying the diffusion of radionuclides in barrier materials, implemented using the apparatus described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Place the rigid barrier material sample inside the tube, and select and set a porous filter membrane based on the shape of the rigid barrier material sample; S2: Select a first water tank and a second water tank with a concave water tank or a spiral water channel structure, place the first water tank on the first end cap, place the second water tank on the second end cap, and seal the first end cap and the second end cap on both sides of the tube body to press the sample in the tube body along the axial direction of the tube body. S3: Connect the fluid circulation drive unit to the first water inlet, the first water outlet, the second water inlet, and the second water outlet respectively, so that the first water tank and the second water tank form independent circulation loops respectively; S4: Inject a solution containing a tracer nuclide into the first water tank, and inject a background solution into the second water tank; S5: Start the fluid circulation drive unit to make the solution circulate independently in the first water tank and the second water tank respectively; S6: During the experimental period, samples are periodically taken from the second water tank, and the concentration changes of the tracer nuclides are detected to study the diffusion behavior of the radionuclides in the rigid barrier material.

9. A method for studying the diffusion of radionuclides in barrier materials, implemented using the apparatus described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Place the soft barrier material sample inside the tube, and attach one or more porous filter membranes to both sides of the sample. S2: Select the first water tank and the second water tank with the structure of spiral water channel, set the first water tank on the first end cap, set the second water tank on the second end cap, and seal the first end cap and the second end cap on both sides of the tube body. Through the connection of the first end cap and the second end cap, the porous filter membrane on both sides is squeezed and adhered to both sides of the sample and the sample is pressed along the axial direction of the tube body. S3: Connect the fluid circulation drive unit to the first water inlet, the first water outlet, the second water inlet, and the second water outlet respectively, so that the first water tank and the second water tank form independent circulation loops respectively; S4: Inject a solution containing tracer nuclides into the first water tank of the spiral water channel structure, and inject a background solution into the second water tank of the spiral water channel structure; S5: Start the fluid circulation drive unit to make the solution circulate independently in the first water tank and the second water tank respectively; S6: During the experimental period, samples are periodically taken from the spiral channel of the second end cap, and the concentration change data of the tracer nuclide therein are detected to study the diffusion behavior of the radionuclide in the soft powder barrier material.

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