Device and method for long-term corrosion test of high-level waste geological disposal packaging container material

Abstract

The invention relates to the field of metal corrosion behavior monitoring and characterization, in particular to a long-term corrosion test device and method for a high-level radioactive waste geological disposal packaging container material. The test device comprises an open container, a sealing material, a temperature-resistant plastic sealing tank, a buffer material, a temperature control component, a packaging container candidate material test sample, a wire and silicone rubber, the sealing material is arranged in the open container, the temperature-resistant plastic sealing tank is embedded in the sealing material, the buffer material is filled in the temperature-resistant plastic sealing tank, and the temperature control component is arranged in the temperature-resistant plastic sealing tank. A sensor for electrochemical impedance spectroscopy measurement, a corrosion weightlessness sample and a corrosion product characterization sample are embedded in the buffer material; the wire penetrates through a sealing tank top cover of the temperature-resistant plastic sealing tank, and the temperature control component is inserted into the sealing tank top cover of the temperature-resistant plastic sealing tank. The device is suitable for long-term corrosion research and evaluation of a packaging container candidate material in a high-level radioactive waste geological disposal buffer material environment, and has the characteristics of multiple functions, high operability, good sealing performance, high stability and real-time measurement.

Description

Technical Field

[0001] The present invention relates to the field of metal corrosion behavior monitoring and characterization, in particular to a device and method for long-term corrosion testing of high-level radioactive waste geological disposal packaging container materials. Background Art

[0002] High-level radioactive waste (HLW) primarily refers to high-level liquid waste and its solidified form produced by spent fuel reprocessing. HLW is a special type of waste that poses a potentially significant threat to the environment. The radionuclides contained in HLW are highly radioactive, toxic, have long half-lives, and generate heat. Once introduced into the human environment, they pose a significant threat and are difficult to eliminate. Therefore, the safe disposal of HLW has become a major issue affecting the sustainable development of nuclear energy, environmental protection, and the well-being of future generations, as well as a significant scientific, technological, and engineering challenge.

[0003] Currently, the internationally recognized method for the safe disposal of high-level radioactive waste is deep geological disposal, which involves burying the waste in stable geological structures approximately 400 to 1000 meters below the surface, effectively isolating it from the biosphere. High-level radioactive waste repositories utilize a "multi-barrier system" design, storing the waste in a container surrounded by a buffer material and a top layer of surrounding rock. The container is typically constructed of metal, and its primary safety function is to contain the waste and prevent groundwater intrusion for at least 1000 years. Therefore, research on the corrosion evolution of container materials in a geological repository environment is essential.

[0004] In order to better study the corrosion behavior and evolution characteristics of packaging container materials in a simulated geological repository environment in the laboratory, it is necessary to develop and design test equipment and methods that can effectively isolate the test system from the surrounding atmospheric environment. Summary of the Invention

[0005] In response to the needs of high-level radioactive waste geological disposal projects, the purpose of the present invention is to provide a device and method for long-term corrosion testing of packaging container materials for high-level radioactive waste geological disposal. The test device has a simple structure, low cost, and diverse design methods; the test method has a stable isolation effect, strong operability, and good long-term stability, and is suitable for long-term corrosion testing of packaging container materials for high-level radioactive waste geological disposal.

[0006] The technical solution of the present invention is:

[0007] A device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste includes an open container, sealing material, a heat-resistant plastic sealed can, buffer material, a temperature control component, test samples of candidate packaging container materials, wires, and silicone rubber. The test samples of candidate packaging container materials include a sensor for electrochemical impedance spectroscopy measurement, a corrosion weight loss sample, and a sample for corrosion product characterization. The specific structure is as follows:

[0008] The open container is filled with sealing material, a heat-resistant plastic sealed can is buried in the sealing material, the heat-resistant plastic sealed can is filled with buffer material, a sensor for electrochemical impedance spectroscopy measurement, a corrosion weight loss sample, and a sample for corrosion product characterization are buried in the buffer material; the wire is passed through the sealed can top cover of the heat-resistant plastic sealed can, the lower end of the wire is connected to the sensor for electrochemical impedance spectroscopy measurement, and the upper end is led out of the open container; the temperature control component is inserted into the sealed can top cover of the heat-resistant plastic sealed can, the lower end of the wire extends into the buffer material, and the upper end of the wire is led out of the open container; the sealed can top cover and the heat-resistant plastic sealed can are sealed by silicone rubber, and the wire, the temperature control component and the sealed can top cover are sealed by silicone rubber.

[0009] In the device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste, the test sample of candidate packaging container materials and the temperature control component have no direct contact with each other and are buried in a buffer material and sealed together in a heat-resistant plastic sealed can; the sealed heat-resistant plastic sealed can is placed in an open container and the heat-resistant plastic sealed can is submerged with sealing material.

[0010] The device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste, wherein the sensor for electrochemical impedance spectroscopy measurement is composed of a first electrode and a second electrode made of the same material, wherein the first electrode and the second electrode each have three or more comb teeth so that the first electrode and the second electrode are interlaced and form a comb shape, and there is a gap between adjacent comb teeth, and the gap is no more than 0.3mm. The test surface area of ​​the first electrode and the second electrode is 1cm 2 .

[0011] In the device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste, a first electrode and a second electrode are fixed between and on the outside by filling with high-temperature resistant insulating resin. The upper end surface of the sensor for electrochemical impedance spectroscopy measurement serves as a test surface. The upper surfaces of the first electrode and the second electrode are exposed and flush with the test surface. A wire is led out from the non-exposed side of each of the first and second electrodes, through a reserved notch on the top cover of the heat-resistant plastic sealed can, for electrochemical impedance spectroscopy data collection. The remaining space in the reserved notch after the wires are led out is sealed with silicone rubber.

[0012] In the device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste, the temperature control component is located in the buffer material and is led out through a reserved notch on the top cover of the heat-resistant plastic sealed tank and connected to a power supply. After the temperature control component is led out, the remaining gap is sealed with silicone rubber.

[0013] In the device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste, after the heat-resistant plastic sealed tank is sealed, silicone rubber is used to seal the sealing circumference of the heat-resistant plastic sealed tank and the sealed tank top cover.

[0014] The apparatus for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste has at least three parallel corrosion weight loss samples, and the sample size is no less than 20 mm × 10 mm × 3 mm; the number of samples for corrosion product characterization is no less than three, and the sample size is no less than 10 mm × 10 mm × 2 mm.

[0015] The device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste has a sealing material of glycerin or liquid paraffin and a buffer material of bentonite.

[0016] A long-term corrosion test method for packaging container materials for geological disposal of high-level radioactive waste, characterized by comprising the following steps:

[0017] (1) Prepare the buffer material bentonite. According to the test requirements, mechanically mix the groundwater and the buffer material bentonite and set aside. The weight of the groundwater should not exceed 70%. At the same time, prepare an open container and sealing materials such as glycerin or liquid paraffin.

[0018] (2) Using wire cutting equipment, the metal sheet of the candidate material of the packaging container is precisely processed into the first electrode and the second electrode of the sensor for electrochemical impedance spectroscopy measurement, the corrosion weight loss sample, and the sample for corrosion product characterization according to the designed size;

[0019] (3) Welding a wire to the non-exposed side of the first electrode and the second electrode respectively; interlacing the first electrode and the second electrode into a comb shape, with gaps between adjacent comb teeth, and fixing them in a mold; then filling the space between the first electrode and the second electrode and the outside with a high-temperature resistant insulating resin, placing them in an oven for constant temperature curing and fixing, and obtaining a sensor for electrochemical impedance spectroscopy measurement; mechanically grinding the test surface of the sensor for electrochemical impedance spectroscopy measurement to 2000# silicon carbide sandpaper, drying it with cold air, and drying it in a dryer for 24 hours before use;

[0020] (4) The corrosion weight loss samples were mechanically water-grinded to 2000# silicon carbide sandpaper, dried with cold air, degreased with anhydrous ethanol, and placed in a desiccator for 24 h. The length, width, and thickness of each sample were then recorded with a vernier caliper. The surface area S of each sample was calculated, and the initial mass W0 of each sample was recorded.

[0021] (5) The samples for corrosion product characterization were mechanically water-grinded to 2000# silicon carbide sandpaper, dried with cold air, degreased with anhydrous ethanol, and placed in a desiccator for 24 hours before use;

[0022] (6) Place the electrochemical impedance spectroscopy sensor, the corrosion weight loss sample, and the corrosion product characterization sample into a heat-resistant plastic sealed can, then fill it with bentonite as a buffer material, insert a temperature control component, and compact it according to the test requirements so that the bentonite fills the entire sealed can and then cover the sealed can top cover; seal the remaining gap on the sealed can top cover with silicone rubber, and seal the sealing ring of the heat-resistant plastic sealed can and the sealed can top cover with silicone rubber;

[0023] (7) Place the sealed heat-resistant plastic can into an open container and fill it with sealing material until the liquid level of the sealing material is at least 15 mm above the top of the heat-resistant plastic can;

[0024] (8) The sensor for electrochemical impedance spectroscopy measurement is connected to the electrochemical workstation through a wire, and the temperature control component is connected to the power supply. When the temperature control component indicates that the temperature of the buffer material reaches the test set value, the evolution of the electrochemical impedance spectrum of the sensor over time is regularly measured and recorded;

[0025] (9) After the test, take out the corrosion weight loss sample, remove the corrosion products and weigh the mass of each parallel sample, record it as W1, and calculate its corrosion rate V according to the corrosion weight loss ΔW, density ρ, corrosion time T and surface area S of the sample; take out the sample for corrosion product characterization, dry it in an oxygen-free environment, and characterize the corrosion product morphology, corrosion morphology, corrosion product composition and corrosion type.

[0026] The design concept of the present invention is:

[0027] (1) The present invention utilizes the fluidity of glycerol or liquid paraffin and the characteristics of not reacting with water and silicone rubber. Using it as a sealing material can effectively isolate the isolated heat-resistant plastic sealed can with a lid from the air environment.

[0028] (2) Glycerin or liquid paraffin has a high ignition point and is non-toxic. It can provide long-term and stable isolation for heat-resistant plastic sealed cans with lids that are isolated at temperatures below 130°C.

[0029] (3) While measuring the electrochemical impedance spectrum of electrodes made of candidate materials for high-level radioactive waste geological disposal packaging containers, the corrosion weight loss sample and the corrosion product characterization sample are placed in the buffer material system. This allows for simultaneous monitoring of the corrosion rate of the candidate packaging container material and detection of corrosion parameters such as the morphology, phase composition, and corrosion type of the corrosion product. Therefore, the present invention is suitable for long-term corrosion research and evaluation of candidate packaging container materials in a buffer material environment for high-level radioactive waste geological disposal, and has the characteristics of multifunctionality, strong operability, good sealing, strong stability, and real-time measurement.

[0030] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0031] (1) The sealing material used in the present invention is a viscous liquid with good fluidity. The material is easily available, non-toxic, and not easily volatile. It can effectively isolate the air environment of the heat-resistant plastic sealed can with a lid, effectively avoiding the disadvantages of other sealing methods such as poor reliability and durability.

[0032] (2) The long-term corrosion test method for packaging container materials for geological disposal of high-level radioactive waste provided by the present invention has a simple process, is environmentally friendly and pollution-free, has a stable isolation effect, and has a simple device structure, diverse design methods, and strong operability. It is suitable for long-term corrosion test research on packaging container materials for geological disposal of high-level radioactive waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of an apparatus for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste according to an embodiment of the present invention;

[0034] Figure 2 for Figure 1 Side view of the structure of the sensor used for electrochemical impedance spectroscopy measurement.

[0035] Description of reference numerals:

[0036] 10. Apparatus for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste; 100. Open container; 200. Sealing material; 300. Heat-resistant plastic sealed can; 310. Sealed can top cover; 400. Cushioning material; 500. Temperature control component; 610. Sensor for electrochemical impedance spectroscopy measurement; 611. First electrode; 612. Second electrode; 613. Conductor; 614. High-temperature-resistant insulating resin; 620. Corrosion weight loss sample; 630. Sample for corrosion product characterization; 700. Silicone rubber. DETAILED DESCRIPTION

[0037] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0038] It should be noted that when an element is referred to as being “fixed to” another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or there may be an intermediate element.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] See also Figure 1 As shown, this embodiment relates to an apparatus 10 for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste. The apparatus 10 includes an open container 100, a sealing material 200, a temperature-resistant plastic sealed can 300, a buffer material 400, a temperature control component 500, a test sample of candidate packaging container materials, a wire 613, and silicone rubber 700. The test sample of candidate packaging container materials includes a sensor for electrochemical impedance spectroscopy measurement 610, a corrosion weight loss sample 620, and a sample for corrosion product characterization 630. The specific structure is as follows:

[0041] The open container 100 is filled with a sealing material 200, a heat-resistant plastic sealed can 300 is embedded in the sealing material 200, a buffer material 400 is filled in the heat-resistant plastic sealed can 300, and a sensor 610 for measuring electrochemical impedance spectroscopy, a corrosion weight loss sample 620, and a sample 630 for characterizing corrosion products are embedded in the buffer material 400; a wire 613 is passed through the sealed can top cover 310 of the heat-resistant plastic sealed can 300, and its lower end is connected to the electrochemical impedance spectroscopy sensor. The measuring sensor 610 is connected, and its upper end is led out of the open container 100; the temperature control component 500 is inserted into the sealed tank top cover 310 of the heat-resistant plastic sealed tank 300, and its lower end extends into the buffer material 400, and its upper end is led out of the open container 100; the sealed tank top cover 310 and the heat-resistant plastic sealed tank 300 are sealed by silicone rubber 700, and the wire 613, the temperature control component 500 and the sealed tank top cover 310 are sealed by silicone rubber 700.

[0042] The packaging container candidate material test sample and the temperature control component 500 have no direct contact with each other and are buried in the buffer material 400 and sealed together in the temperature-resistant plastic sealed can 300 .

[0043] The sealed heat-resistant plastic can 300 is placed in the open container 100 and is submerged in the sealing material 200 to isolate the test unit from the infiltration of ambient air.

[0044] See also Figure 2As shown, the electrochemical impedance spectroscopy sensor 610 is composed of a first electrode 611 and a second electrode 612 made of the same material; the first electrode 611 and the second electrode 612 each have three or more comb teeth, so that the first electrode 611 and the second electrode 612 are interlaced with each other in a comb shape, and there is a gap between adjacent comb teeth, and the gap is no more than 0.3mm. The test surface area of ​​the first electrode 611 and the second electrode 612 is 1cm 2 .

[0045] See also Figure 2 As shown, the first electrode 611 and the second electrode 612 are fixed between and on the outside by filling with a high-temperature resistant insulating resin 614. The upper end surface of the sensor 610 for electrochemical impedance spectroscopy measurement is the test surface. The upper surfaces of the first electrode 611 and the second electrode 612 are exposed and flush with the test surface. A probe copper wire 613 is led out from the non-exposed side of the first electrode 611 and the second electrode 612 respectively, and then led out through a reserved notch on the sealing tank top cover 310 of the heat-resistant plastic sealing tank 300 for electrochemical impedance spectroscopy data collection. After the copper wire 613 is led out, the remaining gap in the reserved notch is sealed with silicone rubber 700.

[0046] See also Figure 1 As shown, the temperature control component 500 is located in the buffer material 400 and is led out through a reserved notch on the sealed tank top cover 310 of the heat-resistant plastic sealed tank 300 and connected to a power supply; after the temperature control component 500 is led out, the remaining gap is sealed with silicone rubber 700.

[0047] See also Figure 1 As shown, after the heat-resistant plastic sealed can 300 is sealed, the silicone rubber 700 is used to seal the sealing circumference of the heat-resistant plastic sealed can 300 and the sealed can top cover 310 .

[0048] See also Figure 1 As shown, the buffer material 400 is bentonite, which should have a certain compaction degree of 1.2 to 1.85 g / cm according to the test parameter requirements. 3 , and contains a certain proportion of groundwater.

[0049] See also Figure 1 As shown, the number of the corrosion weight loss samples 620 set in parallel is not less than 3, which are used to measure the corrosion rate of the candidate material of the packaging container, and the sample size is not less than 20mm×10mm×3mm; the number of the corrosion product characterization samples 630 is not less than 3, which are used to characterize the corrosion morphology, corrosion product composition and corrosion type of the candidate material of the packaging container, and the sample size is not less than 10mm×10mm×2mm.

[0050] See also Figure 1As shown, the sealing material 200 is glycerin or liquid paraffin, which has good fluidity, is difficult to volatilize, has a flash point of not less than 130° C., and does not react with the silicone rubber 700 and the heat-resistant plastic sealing can 300 .

[0051] See also Figures 1 and 2 As shown, in this embodiment, the device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste, when used for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste, involves a long-term corrosion testing method for packaging container materials for geological disposal of high-level radioactive waste, including the following steps:

[0052] (1) Prepare 400 ml of bentonite as a buffer material. According to the test requirements, mechanically mix the groundwater and the 400 ml of bentonite as a buffer material and set aside, wherein the weight proportion of the groundwater does not exceed 70%; at the same time, prepare an open container 100 and a sealing material 200 ml of glycerin or liquid paraffin;

[0053] (2) using a wire cutting device to precisely process the metal sheet material of the candidate packaging container material into a first electrode 611 and a second electrode 612 of a sensor 610 for electrochemical impedance spectroscopy measurement, a corrosion weight loss sample 620, and a sample 630 for corrosion product characterization according to the designed dimensions;

[0054] (3) Manufacturing a sensor 610 for electrochemical impedance spectroscopy measurement. Weld a probe copper wire 613 to the non-exposed side of the first electrode 611 and the second electrode 612 respectively, and interlace the first electrode 611 and the second electrode 612 in a comb shape, with gaps between adjacent comb teeth and fixed in a mold. Then fill the space between the first electrode 611 and the second electrode 612 and the outside with high-temperature resistant insulating resin 614, place them in an oven for constant temperature curing and then fix them; mechanically grind the test surface of the prepared sensor 610 for electrochemical impedance spectroscopy measurement to 2000# silicon carbide sandpaper, blow dry with cold air, and dry in a dryer for 24 hours before use;

[0055] (4) The corrosion weight loss sample 620 was mechanically water-grinded to 2000# silicon carbide sandpaper, dried with cold air, degreased with anhydrous ethanol, and placed in a desiccator for 24 h. The length, width, and thickness of each sample were then recorded with a vernier caliper to calculate the surface area S of each sample and record the initial mass W0 of each sample.

[0056] (5) The corrosion product characterization sample 630 was mechanically water-grinded to 2000# silicon carbide sandpaper, dried with cold air, degreased with anhydrous ethanol, and placed in a desiccator for 24 hours before use;

[0057] (6) Place the electrochemical impedance spectroscopy sensor 610, the corrosion weight loss sample 620, and the corrosion product characterization sample 630 into the heat-resistant plastic sealed can 300, then fill it with the prepared buffer material 400 bentonite, insert the temperature control component 500, and perform a certain degree of compaction according to the test requirements so that the bentonite fills the entire heat-resistant plastic sealed can 300 and then cover the sealed can top cover 310; seal the remaining gap in the sealed can top cover 310 with silicone rubber 700, and also seal the sealing ring between the heat-resistant plastic sealed can 300 and the sealed can top cover 310 with silicone rubber 700;

[0058] (7) Place the sealed heat-resistant plastic can 300 into the open container 100, and fill it with the sealing material 200 so that the liquid level of the sealing material 200 is at least 15 mm higher than the top of the heat-resistant plastic can 300;

[0059] (8) The electrochemical impedance spectroscopy sensor 610 is connected to the electrochemical workstation via a wire 613 and the temperature control component 500 is connected to a power supply. When the temperature control component 500 indicates that the temperature of the buffer material 400 has reached the test set value, the evolution of the electrochemical impedance spectrum of the electrochemical impedance spectroscopy sensor 610 over time is regularly measured and recorded;

[0060] (9) After the test is completed, the corrosion weight loss sample 620 is taken out, and the mass of each parallel sample is weighed after removing the corrosion products, recorded as W1, and its corrosion rate V is calculated based on the corrosion weight loss ΔW, density ρ, corrosion time T and surface area S of the sample; the corrosion product characterization sample 630 is taken out, dried in an oxygen-free environment, and the corrosion product morphology, corrosion morphology, corrosion product composition and corrosion type are characterized.

[0061] The results of the examples demonstrate that the long-term corrosion testing method for high-level radioactive waste geological disposal container materials of the present invention can effectively simulate the long-term corrosion behavior of container materials in a high-level radioactive waste geological disposal repository environment. Furthermore, through periodic measurements using an electrochemical impedance spectroscopy sensor and characterization of corrosion weight loss samples and corrosion product characterization samples, the corrosion rate, corrosion product morphology, corrosion morphology, corrosion product composition, and corrosion type of candidate high-level radioactive waste geological disposal container materials can be characterized in a high-level radioactive waste geological disposal repository environment. This demonstrates that the long-term corrosion testing method for high-level radioactive waste geological disposal container materials of the present invention is versatile, highly operable, well-sealed, highly stable, and provides real-time measurement capabilities.

[0062] The technical features of the above embodiments can be combined in any manner. To simplify the description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction between the combinations of these technical features, they should be considered to be within the scope of this specification.

[0063] The above-described embodiment merely represents one embodiment of the present invention, and its description is relatively specific and detailed, but it should not be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the appended claims.

Claims

1. A device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste, characterized in that: It includes open containers, sealing materials, heat-resistant plastic sealed cans, buffer materials, temperature control components, test samples of candidate packaging container materials, wires and silicone rubber. The test samples of candidate packaging container materials include sensors for electrochemical impedance spectroscopy measurement, corrosion weight loss samples, and samples for corrosion product characterization. The specific structure is as follows: The open container is filled with sealing material, a heat-resistant plastic sealed can is buried in the sealing material, the heat-resistant plastic sealed can is filled with buffer material, a sensor for electrochemical impedance spectroscopy measurement, a corrosion weight loss sample, and a sample for corrosion product characterization are buried in the buffer material; the wire is passed through the sealed can top cover of the heat-resistant plastic sealed can, the lower end of the wire is connected to the sensor for electrochemical impedance spectroscopy measurement, and the upper end is led out of the open container; the temperature control component is inserted into the sealed can top cover of the heat-resistant plastic sealed can, the lower end of the wire extends into the buffer material, and the upper end of the wire is led out of the open container; the sealed can top cover and the heat-resistant plastic sealed can are sealed by silicone rubber, and the wire, the temperature control component and the sealed can top cover are sealed by silicone rubber.

2. The device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste according to claim 1 is characterized in that: The test sample of the candidate material for the packaging container has no direct contact with the temperature control component and is buried in the cushioning material and sealed together in a temperature-resistant plastic sealed can; the sealed temperature-resistant plastic sealed can is placed in an open container and the temperature-resistant plastic sealed can is submerged with sealing material.

3. The device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste according to claim 1 is characterized in that: The sensor for electrochemical impedance spectroscopy measurement consists of a first electrode and a second electrode made of the same material. The first electrode and the second electrode each have three or more comb teeth, so that the first electrode and the second electrode are interlaced and form a comb shape. There is a gap between adjacent comb teeth, and the gap is no more than 0.3mm. The test surface area of ​​the first electrode and the second electrode is 1cm 2 .

4. The device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste according to claim 3 is characterized in that: The first electrode and the second electrode are fixed together by filling a high-temperature resistant insulating resin between and outside the electrode. The upper end surface of the sensor for measuring electrochemical impedance spectroscopy is a test surface. The upper surfaces of the first electrode and the second electrode are exposed and flush with the test surface. A wire is led out from the non-exposed side of the first electrode and the second electrode respectively, and then led out through a reserved notch on the top cover of the sealing tank of the heat-resistant plastic sealing tank for collecting electrochemical impedance spectroscopy data. The remaining gap in the reserved notch after the wire is led out is sealed with silicone rubber.

5. The device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste according to claim 1 is characterized in that: The temperature control component is located in the buffer material and is led out through a reserved notch on the top cover of the heat-resistant plastic sealed can and is connected to a power supply. After the temperature control component is led out, the remaining gap is sealed with silicone rubber.

6. The device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste according to claim 1 is characterized in that: After the heat-resistant plastic sealed can is sealed, silicone rubber is used to seal the sealing circumference of the heat-resistant plastic sealed can and the top cover of the sealed can.

7. The device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste according to claim 1 is characterized in that: The number of parallel samples for corrosion weight loss samples shall be no less than 3, and the sample size shall be no less than 20mm×10mm×3mm; the number of samples for corrosion product characterization shall be no less than 3, and the sample size shall be no less than 10mm×10mm×2mm.

8. The device for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste according to claim 1 is characterized in that: The sealing material is glycerin or liquid paraffin, and the buffer material is bentonite.

9. A method for long-term corrosion testing of packaging container materials for geological disposal of high-level radioactive waste using the apparatus according to any one of claims 1 to 8, characterized in that: The steps include: (1) Prepare the buffer material bentonite. According to the test requirements, mechanically mix the groundwater and the buffer material bentonite and set aside. The weight of the groundwater should not exceed 70%. At the same time, prepare an open container and sealing materials such as glycerin or liquid paraffin. (2) Using wire cutting equipment, the metal sheet of the candidate material of the packaging container is precisely processed into the first electrode and the second electrode of the sensor for electrochemical impedance spectroscopy measurement, the corrosion weight loss sample, and the sample for corrosion product characterization according to the designed size; (3) Welding a wire to the non-exposed side of the first electrode and the second electrode respectively; interlacing the first electrode and the second electrode into a comb shape, with gaps between adjacent comb teeth, and fixing them in a mold; then filling the space between the first electrode and the second electrode and the outside with a high-temperature resistant insulating resin, placing them in an oven for constant temperature curing and fixing, and obtaining a sensor for electrochemical impedance spectroscopy measurement; mechanically grinding the test surface of the sensor for electrochemical impedance spectroscopy measurement to 2000# silicon carbide sandpaper, drying it with cold air, and drying it in a dryer for 24 hours before use; (4) The corrosion weight loss samples were mechanically water-grinded to 2000# silicon carbide sandpaper, dried with cold air, degreased with anhydrous ethanol, and placed in a desiccator for 24 h. The length, width, and thickness of each sample were then recorded with a vernier caliper. The surface area S of each sample was calculated, and the initial mass W0 of each sample was recorded. (5) The samples for corrosion product characterization were mechanically water-grinded to 2000# silicon carbide sandpaper, dried with cold air, degreased with anhydrous ethanol, and placed in a desiccator for 24 hours before use; (6) Place the electrochemical impedance spectroscopy sensor, the corrosion weight loss sample, and the corrosion product characterization sample into a heat-resistant plastic sealed can, then fill it with bentonite as a buffer material, insert a temperature control component, and compact it according to the test requirements so that the bentonite fills the entire sealed can and then cover the sealed can top cover; seal the remaining gap on the sealed can top cover with silicone rubber, and seal the sealing ring of the heat-resistant plastic sealed can and the sealed can top cover with silicone rubber; (7) Place the sealed heat-resistant plastic can into an open container and fill it with sealing material until the liquid level of the sealing material is at least 15 mm above the top of the heat-resistant plastic can; (8) The sensor for electrochemical impedance spectroscopy measurement is connected to the electrochemical workstation through a wire, and the temperature control component is connected to the power supply. When the temperature control component indicates that the temperature of the buffer material reaches the test set value, the evolution of the electrochemical impedance spectrum of the sensor over time is regularly measured and recorded; (9) After the test, take out the corrosion weight loss sample, remove the corrosion products and weigh the mass of each parallel sample, record it as W1, and calculate its corrosion rate V according to the corrosion weight loss ΔW, density ρ, corrosion time T and surface area S of the sample; take out the sample for corrosion product characterization, dry it in an oxygen-free environment, and characterize the corrosion product morphology, corrosion morphology, corrosion product composition and corrosion type.

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