Permeability testing device and testing method

Abstract

The invention provides a permeability testing device and a permeability testing method, and relates to the technical field of permeability testing. The device is characterized in that a trapping liquid is contained in a storage container; the pipe body penetrates through the storage container, the two ends of the pipe body are located outside the storage container and are sealed, and liquid with the permeability to be tested is contained in the pipe body; the first valve is arranged on the top of the storage container. According to the permeability testing device provided by the invention, the permeability of the liquid in the pipeline can be tested, and the permeability testing device provided by the invention is convenient to use and low in production cost.

Description

Technical Field

[0001] The present invention relates to the technical field of permeability testing, and in particular to a permeability testing device and a testing method. Background Art

[0002] Permeability testing is an important method for evaluating the ability of materials to penetrate liquids, and is widely used in many fields such as materials science, chemical engineering, and environmental engineering. Permeability is affected by many factors, including the microstructure and porosity of the material and the physical and chemical properties of the liquid itself. Accurately measuring permeability is crucial for material selection, environmental monitoring, and product performance evaluation, and can help engineers and researchers develop more reasonable design plans and safety measures.

[0003] However, there is a lack of research and relevant data on the permeability of liquids (such as tritiated water) in pipelines, especially the permeability test of tritiated water. As a special fluid, the permeability characteristics of tritiated water are of great significance to environmental safety and engineering design. Therefore, how to effectively measure the permeability of liquids in pipelines has become a scientific problem that needs to be solved urgently. This is not only crucial to ensure the integrity and safety of the pipeline system, but also provides new directions and challenges for further research.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] In order to solve the above problems, the present invention discloses a permeability testing device and a testing method.

[0006] Other features and advantages of the present disclosure will become apparent from the following detailed description, or may be learned in part by the practice of the present disclosure.

[0007] On the one hand, a permeability testing device is provided, comprising:

[0008] A storage container, wherein the storage container is used to hold the captured liquid;

[0009] A tube body, the tube body passes through the storage container, and both ends of the tube body are located outside the storage container, the two ends of the tube body are sealed, and the tube body contains a liquid with a permeability to be tested;

[0010] A first valve is provided on the top of the storage container, and the first valve is used to input the captured liquid;

[0011] A pressure gauge is installed at one end of the tube body outside the storage container, and a second valve is installed at the other end of the tube body outside the storage container. The second valve is used to add the liquid to be tested for permeability into the tube body, and the second valve is also used to connect with an external pressurizing device so that the pressurizing device pressurizes the inner cavity of the tube body;

[0012] Both ends of the pipe body are provided with plugging heads.

[0013] As a preferred technical solution, a support portion is provided on the side of the storage container, and the support portion is distributed at the four corners of the side.

[0014] As a preferred technical solution, the height of the support portion is greater than the length of the extension of the tube body extending out of the storage container, and when the storage container is rotated until the support portion is located below the storage container, the tube body is in a vertical state.

[0015] As a preferred technical solution, the liquid to be tested for permeability is tritiated water, and the capture liquid is ultrapure water.

[0016] As a preferred technical solution, applied to the permeability testing device as described above, the method includes:

[0017] Add the liquid whose permeability is to be tested into the tube body and seal the tube body;

[0018] Adding the capture liquid into the storage container and closing the first valve;

[0019] Opening the first valve at a first time interval to take samples, and testing the radioactivity concentration of the nuclides in the sampled samples to obtain the radioactivity concentration of the nuclides outside the tube body;

[0020] Determine the radioactivity of the nuclide based on the radioactivity concentration of the nuclide outside the tube;

[0021] Under the condition that the radioactivity of the nuclide does not change with time, the diffusion coefficient of the tube to the liquid is obtained.

[0022] As a preferred technical solution, the liquid whose permeability is to be tested is added into the tube body, and the tube body is sealed, including any of the following:

[0023] Add the liquid whose permeability is to be tested into the tube body through a port of the tube body, and seal the tube body;

[0024] Adding the liquid whose permeability is to be tested into the tube body through the second valve, and closing the second valve to seal the tube body;

[0025] The liquid whose permeability is to be tested is added into the tube body through the second valve, and the tube body is pressurized. After pressurization, the second valve is closed to seal the tube body.

[0026] As a preferred technical solution, the ratio of the volume of the capture liquid in the storage container to the volume of the sample is greater than or equal to 80.

[0027] As a preferred technical solution, the first valve is opened every 10 days to take samples, and the radioactivity concentration of the nuclides in the sampled samples is tested to obtain the radioactivity concentration of the nuclides outside the tube body.

[0028] As a preferred technical solution, a curve of permeation flux changing with time is drawn. When the permeation curve shows that the permeation reaches a steady state, that is, when the radioactivity does not change with time, the test ends.

[0029] As a preferred technical solution, when the radioactivity does not change with time, at the end of the test, the tested tube is taken out, the tube is crushed, a sample is prepared, and the tritium activity concentration in the tube is measured.

[0030] The beneficial technical effects of the present invention are:

[0031] 1. The permeability testing device of the present invention can be used to test the permeability of the liquid in the pipeline, and the permeability testing device provided by the present invention is easy to use and has low production cost.

[0032] 2. Both ends of the tube body are located outside the storage container, which can prevent the liquid in the tube body from leaking into the storage container and affecting the test results.

[0033] 3. A support portion is provided to facilitate adding liquid into the tube body.

[0034] 4. Pressurize the inner cavity of the tube so that the permeability of the liquid in the tube can be tested in a short period of time.

[0035] 5. Add enough capture liquid to the storage container to ensure that at least 80 samples are collected to ensure the accuracy of the test results.

[0036] 6. A test method is provided for testing the tritiated water permeability of pipes. The test is simple and the production cost of the test device is low.

[0037] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0039] Figure 1 A schematic diagram of the structure of a permeability testing device in one embodiment of the present disclosure is shown;

[0040] Figure 2 A schematic structural diagram of a permeability testing device in another embodiment of the present disclosure is shown;

[0041] Figure 3 A schematic structural diagram of a permeability testing device in another embodiment of the present disclosure is shown;

[0042] Figure 4 A schematic structural diagram of a permeability testing device in another embodiment of the present disclosure is shown;

[0043] Figure 5 A permeability testing method in an embodiment of the present disclosure is shown;

[0044] Figure 6 A partial cross-sectional schematic diagram of a tube body in an embodiment of the present disclosure is shown.

[0045] Description of the accompanying drawings: storage container 1; tube body 2; first valve 3; support part 4; voltmeter 5; second valve 6. DETAILED DESCRIPTION

[0046] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the disclosure will be more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0047] In addition, the accompanying drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0048] It should be understood that the various steps described in the method embodiments of the present disclosure may be performed in different orders and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present disclosure is not limited in this respect.

[0049] It should be noted that the concepts such as "first" and "second" mentioned in the present disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0050] It should be noted that the modifications of "one" and "plurality" mentioned in the present disclosure are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0051] Figure 1 A schematic diagram of the structure of a permeability testing device in one embodiment of the present disclosure is shown. Figure 1 As shown, a permeability testing device may include: a storage container 1, in which a capture liquid is contained; a tube body 2, which passes through the storage container 1, and both ends of the tube body 2 are located outside the storage container 1, the two ends of the tube body 2 are sealed, and the tube body 2 contains a liquid whose permeability is to be tested; and a first valve 3, which is arranged on the top of the storage container 1.

[0052] In the disclosed embodiment, the capture liquid is a capture liquid used to test the permeability of the liquid in the tube body 2, and the liquid in the tube body 2 can diffuse into the capture liquid through the tube body 2. The disclosed embodiment does not limit what kind of capture liquid the capture liquid is. For example, the capture liquid is ultrapure water. For another example, the capture liquid is multiply distilled water. For example, the capture liquid is double distilled water or triple distilled water. It should be noted that the capture liquid is added to the storage container 1 through the first valve 3.

[0053] In the disclosed embodiment, the liquid to be tested for permeability may be an inorganic compound solution carrying radioactive nuclides. For example, the liquid to be tested for permeability may be tritiated water. For example, the liquid to be tested for permeability may be a salt-containing tritiated water sample.

[0054] In the embodiment of the present disclosure, the tube body 2 is sealed and connected to the storage container 1 at the penetration point. The embodiment of the present disclosure does not limit how to achieve the seal. For example, the seal is achieved by an O-ring. For another example, the tube body 2 and the storage container 1 are integrally injection molded / cast. For another example, the tube body 2 and the storage container 1 are threaded and detachably connected.

[0055] In the embodiment of the present disclosure, there is no limitation on the shapes of the tube body 2 and the storage container 1. For example, the cross section of the tube body 2 may be circular, elliptical, or rectangular. The storage container 1 may be cuboid, spherical, cubic, or truncated cone-shaped. For example, the tube body 2 is cylindrical, and the storage container 1 is cuboid.

[0056] In the embodiment of the present disclosure, the present disclosure does not limit how to achieve sealing at both ends of the tube body 2. For example, when the material of the tube body 2 is thermoplastic, the two ends of the tube body 2 are sealed with a first plug, and the first plug is connected to the two ends of the tube body 2 by hot melt, wherein the material of the first plug is the same as that of the tube body 2. It should be noted that when the first plug is made of the same material as that of the tube body 2, it is beneficial for the first plug to be connected to the two ends of the tube body 2 by hot melt, and there is a first plug at each end of the tube body 2. The material of the tube body 2 can be one of polypropylene, polyvinyl chloride and polyethylene. Exemplarily, the material of the tube body 2 can be polyethylene.

[0057] For another example, when the tube body 2 is made of metal material, the two ends of the tube body 2 are blocked with a second plug, the second plug is threadedly connected to the tube body 2, and the material of the second plug is the same as that of the tube body 2. It should be noted that when the material of the second plug is the same as that of the tube body 2, it is beneficial for the second plug to be connected to the two ends of the tube body 2 through threaded sealing. There is a second plug at each end of the tube body 2. The material of the tube body 2 can be one of stainless steel, carbon steel, alloy steel, titanium alloy, aluminum alloy and copper alloy. Exemplarily, the material of the tube body 2 is stainless steel.

[0058] In the disclosed embodiment, both ends of the tube body 2 are located outside the storage container 1, which can prevent the liquid in the tube body 2 from leaking into the storage container 1 and affecting the test results.

[0059] In the embodiment of the present disclosure, the embodiment of the present disclosure does not limit how to add liquid into the tube body 2. For example, when the tube body 2 is detachably connected to the storage container 1, first seal one end of the tube body 2, add liquid into the tube body 2, and then seal the other end of the tube body 2. After that, the tube body 2 containing the permeability liquid to be tested is installed on the storage container 1. For another example, when the tube body 2 is fixedly connected to the storage container 1, first seal one end of the tube body 2, add liquid into the tube body 2, and then seal the other end of the tube body 2. In order to facilitate the addition of liquid into the tube body 2, the tube body 2 can be placed vertically first. For example, Figure 2 As shown, a support portion 4 is installed on one side of the storage container 1. When the storage container 1 is rotated to the point where the support portion 4 is located below the storage container 1, the tube body 2 is in a vertical state. The support portion 4 is used to support the storage container 1 so that the tube body 2 is in a vertical state, which is convenient for adding liquid into the tube body 2. The specific structure of the support portion 4 is not limited in the embodiments of the present disclosure. For example, the support portion 4 includes a plurality of support rods. The height of the support portion 4 is greater than the length of the extension portion of the tube body 2 extending out of the storage container 1. When the storage container is rotated to the point where the support portion 4 is located below the storage container 1, the tube body 2 is in a vertical state. For another example, the support portion 4 is a retractable support frame, which is extended when in use and retracted when no liquid needs to be added.

[0060] The permeability testing device provided by the present disclosure can be used to test the permeability of liquid in a pipeline, and the permeability testing device provided by the present disclosure is easy to use and has low production cost.

[0061] The above permeability test device can test the permeability of the liquid to be tested (such as tritiated water) in the pipe body at normal pressure. When the pipe body is a hard and high-density material, it may not be possible to obtain more data in a short-term test. If the measurement results are all lower than the detection limit (about 1Bq / L (becquerel per liter)), the specific permeability value cannot be obtained, and the following permeability test device is used to increase the pressure for further testing. If the permeability value can be obtained, continue to test pipes of different specifications.

[0062] Figure 3 A schematic diagram of the structure of a permeability testing device in another embodiment of the present disclosure is shown. Figure 3 As shown, a permeability testing device may include: a storage container 1, in which a capture liquid is contained; a tube body 2, which penetrates the storage container 1, and both ends of the tube body 2 are located outside the storage container 1, the two ends of the tube body 2 are sealed, and the tube body 2 contains a liquid to be tested for permeability; and a first valve 3, which is arranged on the top of the storage container 1. A pressure gauge 5 is installed at one end of the tube body 2 located outside the storage container 1, and a second valve 6 is installed at the other end of the tube body 2 located outside the storage container 1. Both the voltmeter 5 and the second valve 6 are located outside the storage container 1. The second valve 6 is used to add the liquid to be tested for permeability into the tube body 2, and the second valve 6 is also used to connect with an external pressurizing device so that the pressurizing device pressurizes the inner cavity of the tube body 2, so that the permeability of the liquid in the tube body 2 can be tested in a short time. Exemplarily, the liquid to be tested for permeability (such as a tritiated water standard solution) is added into the tube body 2 through the second valve 6, and then nitrogen is added into the tube body 2 through the second valve 6 to a pressure of 0.5 MPa (megapascal) and then the second valve 6 is closed.

[0063] In the disclosed embodiment, the capture liquid is a capture liquid used to test the permeability of the liquid in the tube body 2, and the liquid in the tube body 2 can diffuse into the capture liquid through the tube body 2. The disclosed embodiment does not limit what kind of capture liquid the capture liquid is. For example, the capture liquid is ultrapure water. For another example, the capture liquid is multiply distilled water. For example, the capture liquid is double distilled water or triple distilled water. It should be noted that the capture liquid is added to the storage container 1 through the first valve 3. The tube body 2 located in the storage container 1 is immersed in the capture liquid.

[0064] In the disclosed embodiment, the liquid to be tested for permeability may be an inorganic compound solution carrying radioactive nuclides. For example, the liquid to be tested for permeability is tritiated water. For example, the liquid to be tested for permeability is a salt-containing tritiated water sample.

[0065] In the embodiment of the present disclosure, the tube body 2 is sealed and connected to the storage container 1 at the penetration point. The embodiment of the present disclosure does not limit how to achieve the seal. For example, the seal is achieved by an O-ring. For another example, the tube body 2 and the storage container 1 are integrally injection molded / cast. For another example, the tube body 2 and the storage container 1 are threaded and detachably connected.

[0066] In the embodiment of the present disclosure, there is no limitation on the shapes of the tube body 2 and the storage container 1. For example, the cross section of the tube body 2 may be circular, elliptical or rectangular. The storage container 1 may be cuboid, spherical, cube or truncated cone.

[0067] The following describes the installation positions of the voltmeter and the second valve.

[0068] As a preferred technical solution, Figure 3 As shown, the voltmeter 5 can be installed at one end of the pipe body 2, and the second valve 6 can be installed at the other end of the pipe body 2.

[0069] In another embodiment, if Figure 4 As shown, the voltmeter 5 and the second valve 6 are installed on the pipe body 2. The voltmeter 5 and the second valve 6 are both sealed and connected to the pipe body 2. When the voltmeter 5 and the second valve 6 are installed on the pipe body 2, the embodiment of the present disclosure does not limit how the two ends of the pipe body 2 are sealed. For example, when the material of the pipe body 2 is thermoplastic plastic, the two ends of the pipe body 2 are blocked with a first plug, and the first plug is connected to the two ends of the pipe body 2 by hot melting, wherein the material of the first plug is the same as the material of the pipe body 2. It should be noted that when the first plug is the same as the material of the pipe body 2, it is conducive to the first plug being connected to the two ends of the pipe body 2 by hot melting, and there is a first plug at each end of the pipe body 2. The material of the pipe body 2 can be one of polypropylene, polyvinyl chloride and polyethylene. Exemplarily, the material of the pipe body 2 can be polyethylene. For another example, when the pipe body 2 is a metal material, the two ends of the pipe body 2 are blocked with a second plug, and the second plug is threadedly connected to the pipe body 2, and the material of the second plug is the same as the material of the pipe body 2. It should be noted that when the material of the second plug is the same as that of the tube body 2, it is advantageous for the second plug to be connected to both ends of the tube body 2 through threaded sealing. There is a second plug at each end of the tube body 2. The material of the tube body 2 can be one of stainless steel, carbon steel, alloy steel, titanium alloy, aluminum alloy and copper alloy. Exemplarily, the material of the tube body 2 is stainless steel.

[0070] The embodiment of the present disclosure applies pressure to the tube body through the second valve, so that the permeability of the liquid in the tube body can be tested in a short period of time, thereby improving the test efficiency.

[0071] Based on the same inventive concept, the present disclosure also provides a permeability testing method, as described in the following embodiments. Since the principle of solving the problem in the method embodiment is similar to that in the above-mentioned device embodiment, the implementation of the method embodiment can refer to the implementation of the above-mentioned device embodiment, and the repeated parts will not be repeated.

[0072] Figure 5 A permeability test method in an embodiment of the present disclosure is shown. Figure 5 As shown, the permeability testing device applied to the above embodiment may include the following S501 to S505.

[0073] S501, adding liquid whose permeability is to be tested into the tube body, and sealing the tube body.

[0074] In the disclosed embodiment, the activity of the nuclides contained in the liquid to be tested for permeability is a known quantity. How to seal the tube body has been described in the above embodiment and will not be repeated here.

[0075] How to add the liquid to be tested for permeability into the pipe body can be determined for normal pressure testing or pressure testing.

[0076] As a preferred technical solution, the permeability test is a normal pressure test, and the liquid with the permeability to be tested is added into the tube body, and the tube body is sealed, including any one of the following: adding the liquid with the permeability to be tested into the tube body through a port of the tube body, and sealing the tube body; adding the liquid with the permeability to be tested into the tube body through a second valve, and closing the second valve to seal the tube body.

[0077] In another embodiment, the permeability test is a pressure test, and the liquid whose permeability is to be tested is added into the tube body, and the tube body is sealed, which may include: adding the liquid whose permeability is to be tested into the tube body through the second valve, and pressurizing the tube body, and closing the second valve after pressurization to seal the tube body. Exemplarily, a tritiated water standard solution is filled into the tube body, and nitrogen is added to the pressure of 0.5 MPa before closing the second valve.

[0078] S502, adding the capture liquid into the storage container and closing the first valve.

[0079] In the embodiment of the present disclosure, the amount of the capture liquid added can be determined according to the test requirements. Exemplarily, the ratio of the volume of the capture liquid in the storage container to the volume of the sampled sample is greater than or equal to 80. For example, the ratio of the volume of the capture liquid in the storage container to the volume of the sampled sample is any value between 80 and 200. The embodiment of the present disclosure ensures that the test can collect enough samples to ensure the accuracy of the test results by adding capture liquid that satisfies at least 80 samplings to the storage container.

[0080] S503, opening the first valve at a first time interval to take samples, and testing the radioactivity concentration of the nuclides in the sampled samples to obtain the radioactivity concentration of the nuclides outside the tube body.

[0081] In the disclosed embodiment, the first time length is determined according to the properties of the liquid whose permeability is to be tested and the material of the tube body. For a liquid with a high permeability and a tube body with a low density, the value of the first time length can be determined as a small value. For a liquid with a low permeability and a tube body with a high density, the value of the first time length can be determined as a large value. Exemplarily, the value range of the first time length can be 8-30 days. For a liquid with a high permeability and a tube body with a low density, the value of the first time length can be determined as 8 days. For a liquid with a low permeability and a tube body with a high density, the value of the first time length can be determined as 30 days.

[0082] Exemplarily, when the liquid is standard tritiated water and the material of the tube is stainless steel, the first period is 10 days.

[0083] In the embodiments of the present disclosure, the present disclosure does not limit the use of equipment to test the radioactivity concentration of the nuclides in the sampled sample. For example, the radioactivity concentration of the nuclides in the sampled sample is tested by a liquid scintillation spectrometer.

[0084] S504, determining the radioactivity of the nuclide according to the radioactivity concentration of the nuclide outside the tube body.

[0085] In the disclosed embodiment, the radioactivity of the nuclide is the activity of the nuclide that seeps out of the tube wall within time t, where t is the time from the start of the test to the sampling test. The radioactivity of the nuclide can be calculated based on the radioactivity concentration of the nuclide outside the tube body and the volume of the remaining capture liquid in the storage container.

[0086] S505, obtaining the diffusion coefficient of the tube body to the liquid when the radioactivity of the nuclide does not change with time.

[0087] In the embodiment of the present disclosure, when the cross-section of the tube is a circular ring, the diffusion coefficient of the sample can be solved by the Fick's law expression in the cylindrical coordinate system.

[0088] It should be noted that, in the whole process of the nuclide in the liquid penetrating into the material, if the time required for the surface process is much shorter than the time for the nuclide to diffuse inside the material matrix, the penetration rate of the nuclide is mainly determined by the diffusion process, that is, the diffusion behavior of the nuclide becomes the controlling factor of the nuclide penetration speed, and the diffusion coefficient obtained by the test can be equivalent to the permeability of the liquid.

[0089] It should be noted that when testing each pipe body, a separate permeability testing device is used to avoid cross contamination between pipe bodies.

[0090] The disclosed embodiment uses a normal pressure permeability test device to test the permeability of the tube body on a solution containing nuclides. The test can evaluate the protection capability of the tube body material against radioactive nuclides and ensure its safe application in nuclear energy or radioactive waste treatment. It helps monitor and analyze potential radioactive contamination and supports environmental protection and safety management. The normal pressure permeability test device has a simple structure and low production cost.

[0091] The disclosed embodiment uses a pressurized permeability testing device to test the permeability of the tube body on the solution contained therein. The pressurized environment can more effectively simulate actual use conditions, obtain more realistic permeability data, and ensure that the tube body can still effectively isolate radioactive nuclides under high pressure conditions to ensure safety. It can also more comprehensively evaluate the performance of various materials under different pressures, providing a basis for selecting suitable materials. In addition, by applying pressure, the penetration rate of the solution through the tube body can be accelerated, thereby shortening the experimental time. The pressurized permeability testing device is relatively simple in structure and has a low production cost.

[0092] The following description will be made by taking tritiated water as an example of the liquid to be tested for permeability.

[0093] In the related technology, there are tritium gas and tritiated water permeability tests for flat materials (tritiated water is rare), but there is no tritiated water permeability test method for cylindrical pipes (tube bodies). Tritiated water is an inorganic compound composed of one hydrogen, one tritium and one oxygen, with the chemical formula HTO. When tritiated water exists in the pipe, the permeation effect of tritium needs to be considered.

[0094] The quantitative evaluation parameters of tritium's diffusion and penetration behavior in solid materials include permeability, diffusion coefficient and solubility coefficient. For the whole process of tritium's penetration in the material, if the time required for the surface process is much shorter than the time for tritium to diffuse inside the material matrix, the penetration rate of tritium is mainly determined by the diffusion process, that is, the diffusion behavior of tritium becomes the controlling factor of tritium penetration speed, and the diffusion coefficient obtained by the test can be equivalent to the permeability of the liquid.

[0095] There is very little research and data on the permeability of tritiated water in pipes. Therefore, in experimental work, the diffusion and permeability parameters (permeability) of tritium in materials are often measured experimentally according to the task requirements.

[0096] Normal pressure test is as follows: Figure 1 As shown, a tritiated water standard solution (liquid to be tested for permeability) with known activity is filled into the tube body 2, and both ends are sealed and fixed in the storage container 1. The storage container 1 is filled with double distilled water (capture liquid), which can completely immerse the tube body 2. Double distilled water is taken regularly and continuously to measure the tritium activity concentration in the double distilled water. The tritium activity is determined based on the tritium activity concentration in the double distilled water. When the tritium activity does not change with time, the diffusion coefficient of the tube body to the tritiated water standard solution is obtained.

[0097] The experiment was conducted using tube 2 at room temperature and pressure in the laboratory. The water in storage container 1 was collected at different times and the activity concentration of tritium therein was determined using a low-level liquid scintillation spectrometer. The design information of the tritiated water penetration experimental device of tube 2 is as follows:

[0098] (1) Basic functions: Fill the tube body 2 with a tritiated water standard solution, and seal the two ends of the tube body 2. Open the valve, fill the storage container 1 with a quantitative capture solution, and close the first valve 3. After standing for a predetermined time (first time length), open the first valve, and quantitatively sample and prepare the sample for measurement. After sampling, close the first valve and let it stand.

[0099] (2) Sealing of storage container 1: In order to avoid interference and contamination from the external environment, storage container 1 adopts a fully sealed structure. In order to meet the needs of regular sampling and monitoring, a switchable first valve is connected to the upper end of storage container 1. Under the conditions of achieving sample addition and sampling, the area of ​​contact between the material in storage container 1 and the outside world during the sampling process is minimized.

[0100] (3) Tube body sealing: After the two ends of the tube body 2 are sealed, they pass through the storage container 1, so that the outer sealed port is outside the storage container 1, avoiding the problem of misjudgment of the results caused by possible leakage of the port. When the tube body 2 is a polyethylene tube body, the two ends of the polyethylene tube body are sealed with plugs of the same material through hot melt welding. When the tube body 2 is a stainless steel tube body, the two ends of the stainless steel tube body are sealed with plugs of the same material through threads.

[0101] (4) Prevent cross contamination: ① Each tube body 2 uses a set of tube body tritiated water permeation test device (permeability test device) to avoid cross contamination between tube bodies 2. ② The tube body tritiated water permeation test device is sealed with the first valve. The first valve is opened for about 2 minutes each time sampling is performed to minimize excessive contact and contamination with the outside world. ③ Place an open water sample outside the tube body 2 tritiated water permeation test device placed in the same place as an environmental blank, and regularly monitor the tritium in the environmental water to prevent external contamination.

[0102] The pressure test is as follows: a stainless steel rectangular box (referred to as storage container 1) sealed by a first valve 3 is used as the storage container, and a test tube body 2 is embedded with symmetrical holes at the bottom. The tube body 2 is filled with a tritiated water standard solution with a known tritium activity (liquid whose permeability is to be tested). The tube body 2 is sealed and connected to the storage container 1. A pressure gauge 5 is connected to one end of the tube body 2, and a pressure or liquid adding valve (second valve 6) is provided at the other end. A first valve 3 for water injection and water extraction is provided above the storage container 1. The tritiated water permeability test device of the tube body 2 is shown in FIG. Figure 3 shown.

[0103] The tritiated water permeability test device of the tube body 2 has the basic function of testing the permeability of tritium in the liquid in the tube body 2 to the outside of the tube body 2. Fill the tube body 2 with a tritiated water standard solution, add nitrogen to the pressure of 0.5MPa, and then close the second valve 6. Open the first valve 3, fill the storage container 1 with a quantitative capture liquid, and close the first valve 3. After standing for a predetermined time, open the first valve 3, and quantitatively take samples for measurement. After sampling, close the first valve 3 and let it stand. Take the capture liquid regularly and continuously, and measure the tritium activity concentration in the capture liquid. Determine the tritium activity based on the tritium activity concentration in the capture liquid, and obtain the diffusion coefficient of the tube body to the tritiated water standard solution when the tritium activity does not change with time.

[0104] In order to avoid interference and contamination from the external environment, the storage container 1 adopts a fully sealed structure. In order to meet the needs of regular sampling and monitoring, the upper end of the storage container 1 is connected to a switchable first valve, and under the conditions of achieving sample addition and sampling, the area of ​​contact between the material in the storage container 1 and the outside world during the sampling process is minimized.

[0105] The sealing of the tube body 2 is ensured by the device design and connection process disclosed in the present invention. The two ends of the tube body 2 are composed of a second valve 6 and a pressure gauge 4. The tube body 2 passes through the storage container 1, so that the port sealed on the outside is outside the storage container 1, avoiding the problem of misjudgment of the result caused by possible leakage of the port. When the tube body 2 is a polyethylene tube body, the two ends of the polyethylene tube body are sealed by hot-melt welding with plugs of the same material. When the tube body 2 is a stainless steel tube body, the two ends of the stainless steel tube body are threadedly sealed with plugs of the same material.

[0106] In order to effectively prevent possible cross contamination during the test, the experiment uses independent devices, standardized operations, and blank monitoring to avoid cross contamination. ① Each tube body 2 uses a set of permeability test devices to avoid cross contamination between tube bodies 2. ② The permeability test device uses the first valve seal, and the valve is open for about 2 minutes each time the sample is taken to minimize excessive contact and contamination with the outside world. ③ Place an open water sample outside the permeability test device in the same place as an environmental blank, and regularly monitor the tritium in the environmental water to prevent external contamination.

[0107] Exemplarily, the permeability testing device of the present disclosure is used to perform a permeability test of a liquid in a pipe body, and the permeability testing method includes the following steps A1 to A5.

[0108] Step A1, sealing the sample: fill the tube body 2 with a tritium-spiked water sample of known activity. Close the second valve 6. It should be noted that when the tube body 2 is a polyethylene tube body, the second valve 6 and the pressure gauge 5 are welded by hot-melt welding with the same material at both ends of the polyethylene tube body. When the tube body 2 is a stainless steel tube body, the second valve 6 and the pressure gauge 5 are connected by threads of the same material at both ends of the stainless steel tube body.

[0109] Step A2, adding water: open the first valve 3 on the top of the storage container 1, add double distilled water into the storage container 1 in a quantitative manner, and close the first valve 3. The amount of water added should be enough to test at least 80 sampling samples.

[0110] Step A3, regular testing: Take water regularly and continuously, and use liquid scintillation spectrometer to measure the tritium activity concentration in the water after sample preparation. The sampling test frequency is initially set at about once every 10 days.

[0111] Step A4, curve drawing: For each test scheme, the permeation flux of the tube body 2 to tritiated water is calculated, that is, the radioactivity of tritium in the test sample is measured. A curve of the permeation flux changing with time is drawn. When the permeation curve observes that the permeation reaches a steady state, that is, when the radioactivity does not change with time, the test ends.

[0112] Step A5, testing and verifying the tritium concentration of the tube body 2: Taking a certain test scheme as an example, when the tritium penetration reaches a steady state, the tested tube body 2 is taken out, the tube body 2 is crushed, and after the sample is prepared, the tritium activity concentration in the tube body 2 is measured.

[0113] It should be noted that, based on the permeability test device disclosed in the present invention, the tritium activity concentration outside the tube body 2 can be obtained after a certain period of time. Under initial conditions, the tritium activity concentration inside the tube body 2 is 4-5 orders of magnitude higher than the tritium activity concentration outside the tube body 2. Assuming that the tritium that seeps out is mainly a diffusion process of steady-state flow, that is, the driving force of tritium penetration is the concentration gradient caused by the uneven distribution of tritium in the material, then by solving the steady-state diffusion equation of the cylindrical tube and substituting the experimental test data, the diffusion coefficient of the tube body 2 for tritiated water can be obtained. The diffusion equation obtained in steady state is shown in the following formula 1.

[0114]

[0115] Where, D is the diffusion coefficient, in cm2 / s; m is the tritium activity that seeps out of the tube wall within time t, in Bq; t is the time from the start of the test to the water collection measurement, in s; r1 is the inner radius of the tube, in mm; r2 is the outer radius of the tube, in mm; L is the length of the tube (the length inside the permeation box), in mm; C1 is the tritium activity concentration inside the tube, in Bq / L. C2 is the tritium activity concentration outside the tube, in Bq / L.

[0116] The diffusion coefficient is solved according to the above formula 1, and the equation of the diffusion coefficient is obtained as shown in the following formula 2.

[0117]

[0118] Where, D is the diffusion coefficient, in cm2 / s; m is the tritium activity that seeps out of the tube wall within time t, in Bq; t is the time from the start of the test to the water collection measurement, in s; r1 is the inner radius of the tube, in mm; r2 is the outer radius of the tube, in mm; L is the length of the tube (the length inside the storage container), in mm; C1 is the tritium activity concentration inside the tube, in Bq / L. C2 is the tritium activity concentration outside the tube, in Bq / L.

[0119] It should be noted that the lengths indicated by r1 and r2 are as follows Figure 6 As shown, C1 is the tritium activity concentration inside the tube, C1, r1 and r2 are all known quantities, and C2 is the tritium activity concentration in the sample measured by liquid scintillation spectrometer. m can be calculated based on C2 and the volume of water in the storage container 1, that is, m is the product of C2 and the volume of water in the storage container 1.

[0120] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A permeability testing device, characterized in that: include: A storage container, wherein the storage container is used to hold the captured liquid; A tube body, wherein the tube body passes through the storage container, and both ends of the tube body are located outside the storage container, the two ends of the tube body are sealed, and the liquid whose permeability is to be tested is contained in the tube body; A first valve is provided on the top of the storage container, and the first valve is used to input the captured liquid; A pressure gauge is installed at one end of the tube body located outside the storage container, and a second valve is installed at the other end of the tube body located outside the storage container. The second valve is used to add the liquid to be tested for permeability into the tube body, and the second valve is also used to connect with an external pressurizing device so that the pressurizing device pressurizes the inner cavity of the tube body; Both ends of the tube body are provided with plugging heads.

2. A permeability testing device according to claim 1, characterized in that: A supporting portion is provided on the side surface of the storage container, and the supporting portion is distributed at the four corners of the side surface.

3. A permeability testing device according to claim 2, characterized in that: The height of the support portion is greater than the length of the extension portion of the tube extending out of the storage container. When the storage container is rotated until the support portion is located below the storage container, the tube body is in a vertical state.

4. A permeability testing device according to claim 1, characterized in that: The liquid to be tested for permeability is tritiated water, and the capture liquid is ultrapure water.

5. A permeability testing method, characterized in that: Applied to the permeability testing device according to any one of claims 1 to 4, the method comprises: Adding a liquid whose permeability is to be tested into the tube body, and sealing the tube body; Adding the capture liquid into the storage container and closing the first valve; Opening the first valve at a first time interval to take samples, and testing the radioactivity concentration of the nuclides in the sampled samples to obtain the radioactivity concentration of the nuclides outside the tube body; Determining the radioactivity of the nuclide according to the radioactivity concentration of the nuclide outside the tube body; Under the condition that the radioactivity of the nuclide does not change with time, the diffusion coefficient of the tube body to the liquid is obtained.

6. A permeability testing method according to claim 5, characterized in that: The step of adding the liquid to be tested for permeability into the tube body and sealing the tube body comprises any one of the following: Adding a liquid whose permeability is to be tested into the tube body through a port of the tube body, and sealing the tube body; Adding a liquid whose permeability is to be tested into the tube body through a second valve, and closing the second valve to seal the tube body; The liquid whose permeability is to be tested is added into the tube body through the second valve, and the tube body is pressurized. After pressurization, the second valve is closed to seal the tube body.

7. A permeability testing method according to claim 6, characterized in that: The ratio of the volume of the capture liquid in the storage container to the volume of the sample is greater than or equal to 80.

8. A permeability testing method according to claim 5, characterized in that: The first valve is opened for sampling every 10 days, and the radioactivity concentration of the nuclides in the sampled samples is tested to obtain the radioactivity concentration of the nuclides outside the tube body.

9. A permeability testing method according to claim 8, characterized in that: The permeation flux is plotted as a function of time, and the test is terminated when the permeation curve observes that the permeation reaches a steady state, that is, when the radioactivity does not change with time.

10. A permeability testing method according to claim 9, characterized in that: When the radioactivity does not change with time, the test is finished, the tube body to be tested is taken out, the tube body is crushed, a sample is prepared, and the tritium activity concentration in the tube body is measured.

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