Bentonite metal electrochemical corrosion test environment simulation device and measurement system

Abstract

The utility model discloses an electrochemical corrosion test environment simulation device for metals in bentonite and a measuring system, and relates to the technical field of research and development of high-level radioactive waste disposal containers, the electrochemical corrosion test environment simulation device for metals in bentonite comprises a test cavity, a heating device, an oxygen driving system and a solution supply system, the test cavity is used for filling and compacting bentonite and limiting expansion of the bentonite after saturation; the heating device is used for heating bentonite in the test cavity; the oxygen expelling system is used for expelling bentonite in the test cavity and oxygen of the test solution in the solution supply system; and the solution supply system is used for supplying a solution to the bentonite in the test cavity. The test system comprises an electrochemical measurement system and an electrochemical corrosion test environment simulation device for metal in bentonite. According to the scheme provided by the utility model, the corrosion process can be truly and effectively tested through a multi-field coupling effect.

Description

Technical Field

[0001] The utility model relates to the technical field of high-level radioactive waste disposal container research and development, in particular to a device for simulating the test environment of metal electrochemical corrosion in bentonite and a measurement system. Background Technique

[0002] The development and utilization of nuclear energy, while generating huge economic benefits, are also accompanied by the generation of a large amount of high-level radioactive waste. Currently, the internationally recognized method for disposing of high-level radioactive waste is deep geological disposal, that is, a high-level radioactive waste disposal repository is built in a stable geological body about 400-1000 m deep from the ground surface using the concept of a "multiple barrier system" to isolate high-level radioactive waste from the biosphere for a long time. The "multiple barrier system" from the outside to the inside is the surrounding rock, buffer material (bentonite), disposal container, and high-level radioactive waste. As one of the key barriers of the high-level radioactive waste disposal repository, the safety function of the disposal container is to contain high-level radioactive waste within the service life and block the outward migration of radionuclides, which requires that the disposal container does not corrode and fail within the designed service life. Therefore, it is of great significance to study the corrosion behavior of candidate materials for disposal containers in the simulated disposal repository environment.

[0003] The inventor found that when the disposal container serves in the high-level radioactive waste disposal repository, the high-level radioactive waste inside will decay and release heat, resulting in an increase in the temperature of the disposal container; the bentonite outside gradually swells due to being saturated with groundwater and comes into contact with the disposal container. After the disposal repository is closed, microbial activities, the reaction of minerals in the surrounding rock with oxygen, and the diffusion of oxygen in the surrounding rock will consume the oxygen introduced during the construction of the disposal repository, turning the near-field of the disposal container into an anaerobic environment. Therefore, when the disposal container serves in the high-level radioactive waste disposal repository, it may serve in high-temperature (60-90 °C), groundwater-saturated, anaerobic saturated bentonite for a long time and be affected by the multi-field coupling of heat-saturated bentonite pore water chemistry-force-anaerobic.

[0004] However, in the prior art, there is no experimental test system that can realize the multi-field coupling effect to truly and effectively simulate the corrosion process. Based on this, it is urgent to solve the above problems. Content of the Utility Model

[0005] The purpose of the utility model is to provide a device for simulating the test environment of metal electrochemical corrosion in bentonite and a measurement system to solve the problems existing in the above-mentioned prior art and realize the multi-field coupling effect to truly and effectively test the corrosion process.

[0006] To achieve the above purpose, the utility model provides the following solutions:

[0007] The utility model provides a device for simulating the test environment of metal electrochemical corrosion in bentonite, including:

[0008] A test chamber for filling and compacting bentonite to limit the expansion of bentonite after saturation.

[0009] A heating device for heating the bentonite in the test chamber.

[0010] An oxygen removal system for removing oxygen from the bentonite in the test chamber and the test solution in the solution supply system.

[0011] A solution supply system for supplying solution to the bentonite in the test chamber.

[0012] Preferably, the test chamber is formed in a test box made of metal with corrosion resistance and a strength of at least 130 MPa. The heating device includes an electric heating tape covering the outer wall of the test box, and the outer wall of the test box without the electric heating tape is covered with a heat-insulating layer.

[0013] Preferably, the oxygen removal system includes a first gas cylinder for containing inert gas and a second gas cylinder for containing inert gas. The outlet of the first gas cylinder is communicated with the bottom of the test chamber, and a discharge port is arranged at the top of the test chamber. The solution supply system includes a solution supply tank for containing test solution. The outlet end of the second gas cylinder is communicated with a first pipeline, and one end of the first pipeline far from the outlet end of the second gas cylinder extends into the test solution. A second exhaust port is arranged at the top of the solution supply tank, and both the discharge port and the second exhaust port are communicated with a liquid seal tank through pipelines.

[0014] Preferably, the solution supply system further includes a third gas cylinder for containing inert gas. The outlet end of the third gas cylinder is communicated with a second pipeline, and one end of the second pipeline is communicated with the upper space of the solution supply tank. The lower space of the solution supply tank is communicated with the bottom of the test chamber through a liquid inlet pipe.

[0015] The present utility model also provides a system for measuring the electrochemical corrosion of metals in bentonite, including an electrochemical measurement system and the device for simulating the electrochemical corrosion test environment of metals in bentonite as described above. The working electrode of the electrochemical measurement system is made of the candidate material of the disposal container and is used to be buried in the bentonite in the test chamber.

[0016] Preferably, the electrochemical measurement system includes a reference electrode, an auxiliary electrode, an electrochemical workstation and a plurality of working electrodes. The working electrode and the auxiliary electrode form a current loop, and the working electrode and the reference electrode form a voltage loop. A plurality of the working electrodes and the auxiliary electrode are sequentially arranged around the reference electrode, and the distance between them and the reference electrode is 3 - 6 cm.

[0017] Preferably, it further includes a gas content measurement system for detecting the gas release amount in the test chamber during the corrosion test.

[0018] Preferably, the gas content measurement system includes a precision pressure gauge and a gas collecting pipe. The precision pressure gauge is configured to be able to detect the air pressure in the test chamber. One end of the gas collecting pipe is communicated with the test chamber, and the other end is communicated with the atmosphere. Part of the gas collecting pipe is a downward-bent pipe filled with dimethyl silicone oil to seal the gas collecting pipe. A valve and an exhaust port are provided on the gas collecting pipe between the bent pipe and the test chamber. The gas release amount in the test chamber during the corrosion test is calculated by the displacement of the dimethyl silicone oil under the action of air pressure.

[0019] Preferably, a temperature and humidity sensor and an oxygen probe are buried in the bentonite in the test chamber; an oxygen probe is arranged in the solution supply tank of the solution supply system.

[0020] The present utility model has achieved the following technical effects compared with the prior art:

[0021] The solution provided by the present utility model can simulate a multi-field coupling environment to more truly reflect the metal corrosion process, study the corrosion behavior of candidate materials for disposal containers in the simulated repository environment, and provide a basis for the material selection and thickness design of disposal containers. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following described drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is a schematic structural diagram of the metal electrochemistry corrosion measurement system in bentonite provided by the embodiment of the present utility model;

[0024] Figure 2 It is a schematic diagram of electrode layout when three working electrodes are provided;

[0025] In the figure: 1 - test chamber; 2 - bentonite; 3 - working electrode 1; 4 - reference electrode; 5 - auxiliary electrode; 6 - electrochemical workstation; 7 - first gas cylinder; 8 - first intake valve; 9 - first exhaust valve; 10 - liquid seal tank; 11 - water; 12 - first oxygen probe; 13 - data acquisition and control system; 14 - heating tape; 15 - insulation layer; 16 - temperature and humidity sensor; 17 - solution supply tank; 18 - test solution; 19 - second gas cylinder; 20 - second intake valve; 21 - second exhaust valve; 22 - second oxygen probe; 23 - third gas cylinder; 24 - third intake valve; 25 - drain valve; 26 - inlet valve; 27 - precision pressure gauge; 28 - boring pipe; 29 - first ventilation valve; 30 - second ventilation valve; 31 - dimethyl silicone oil; 32 - reference line; 33 - third exhaust valve; 34 - working electrode 2; 35 - working electrode 3. Detailed implementation manners

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the drawings and specific implementation manners.

[0028] The present invention provides a device for simulating the electrochemical corrosion test environment of metals in bentonite, as Figure 1 shown, including: a test chamber, a heating device, an oxygen removal system and a solution supply system.

[0029] The test chamber is used to fill the bentonite 2 compacted to the required degree. Usually, the test chamber is formed in a test box 1. The test box 1 is used to limit the expansion of the bentonite 2 when it reaches saturation, so that the working electrode is subjected to a certain expansion force, thereby simulating the chemical - force coupling corrosion environment of the pore water of saturated bentonite in the near field of the disposal container in the repository. It can be understood that when conducting the test, it is preferably to fill the test box 1 with the bentonite 2 to facilitate simulating the expansion force effect.

[0030] The heating device is used to heat the bentonite 2 in the test chamber to simulate the temperature field environment in the near field of the disposal container caused by the decay heat release of high - level radioactive waste.

[0031] The oxygen removal system is used to remove the oxygen in the bentonite 2 in the test chamber and the test solution in the solution supply system to simulate the anaerobic saturated bentonite environment in the near field of the disposal container in the high - level radioactive waste repository.

[0032] A solution supply system is used to supply solution to bentonite 2 in the test chamber, which can keep bentonite 2 in a state saturated with the test solution 18 for a long time to simulate the infiltration process of groundwater into a high-level radioactive waste repository.

[0033] Therefore, this embodiment can simulate the environment of thermo-saturated bentonite pore water chemistry-mechanics-anaerobic multi-field coupling, and thus more truly reflect the metal corrosion process to study the corrosion behavior of candidate materials for the disposal container in the simulated repository environment, providing a basis for the material selection and thickness design of the disposal container.

[0034] It can be understood that the above embodiments do not limit the specific structures of the heating device, the oxygen removal system and the solution supply system, that is to say, any solution in the prior art that can achieve the above three functions can be applied to the present utility model as a specific embodiment of the present utility model.

[0035] In some embodiments, the test chamber 1 is preferably made of a metal with corrosion resistance and a strength of at least 130 MPa, such as a metal Ni kettle. The heating device includes an electric heating tape 14, and the electric heating tape 14 is laid on the outer wall of the test chamber 1. The outer wall of the test chamber 1 without the electric heating tape 14 is covered with a heat insulation layer 15.

[0036] This embodiment uses the electric heating tape 14 and electric heating sheets to heat the bentonite 2 in the test chamber 1, and uses the heat insulation layer 15 for heat insulation to improve the heating effect. In some embodiments, a heat insulation layer 15 can also be laid outside the electric heating tape 14 to further improve the heat insulation effect.

[0037] The heating device is preferably configured to be able to keep the temperature of bentonite 2 constant within a certain period of time. Therefore, the heating device further includes a data acquisition and control system 13 and a temperature and humidity sensor 16. The temperature and humidity sensor 16 is arranged in the bentonite 2 and is used to measure the temperature and humidity near the electrochemical specimen (i.e., the working electrode) and transmit them to the data acquisition and control system 13. The data acquisition and control system 13 controls the working state of the electric heating tape 14 according to the temperature information so that the bentonite 2 is heated and kept at a certain constant temperature to simulate the temperature field environment formed by the decay heat release of high-level radioactive waste in the disposal container.

[0038] In some embodiments, the oxygen expulsion system includes a first gas cylinder 7 for containing an inert gas and a second gas cylinder 19 for containing an inert gas. The gas outlet of the first gas cylinder 7 is communicated with the bottom of the test chamber, and a discharge port is arranged at the top of the test chamber; the discharge port is communicated with a liquid seal tank 10 through a pipeline. The solution supply system includes a solution supply tank 17 for containing a test solution 18. One end of a first pipeline, which is far away from the gas outlet end of the second gas cylinder 19, extends into the test solution 18 at the gas outlet end of the second gas cylinder 19; a second exhaust port is arranged at the top of the solution supply tank 17, and the second exhaust port is communicated with the liquid seal tank 10 through a pipeline.

[0039] In this embodiment, the oxygen in the bentonite 2 is expelled from bottom to top by an inert gas, thereby creating an anaerobic environment. The air in the test solution 18 is "expelled" by the inert gas. The liquid seal tank 10 and the water 11 therein are used to prevent oxygen from entering the bentonite 2 and the test solution 18 due to air convection, so that the bentonite 2 and the test solution 18 are kept in an anaerobic environment. By mixing the anaerobic bentonite 2 and the test solution 18, an anaerobic saturated bentonite environment of the deep site of the disposal repository is finally simulated.

[0040] When expelling oxygen from the bentonite 2, the first gas cylinder 7 and the test chamber are connected. The first gas cylinder 7 contains a pressurized gas. The pressurized gas flows from the first gas cylinder 7 into the test chamber and "expels" the original air in the bentonite 2 to the liquid seal tank 10 through the discharge port and then discharges it. The liquid seal tank 10 and the water 11 therein are to prevent oxygen from entering the bentonite 2 due to air convection, so that the dry bentonite 2 is kept in an anaerobic environment to simulate the anaerobic environment in the disposal repository.

[0041] When expelling oxygen from the test solution, the second gas cylinder 19 and the solution supply tank 17 are connected. The pressurized gas in the second gas cylinder 19 flows into the solution supply tank 17 and "expels" the original air to the liquid seal tank 10 through the second exhaust port and then discharges it.

[0042] During specific implementation, oxygen sensors are usually arranged in the bentonite 2 and the test solution 18 to detect the oxygen content. After the above "expulsion" process has been carried out for a certain period of time, it is determined whether to stop the "expulsion" according to the information detected by the oxygen sensor. When it is necessary to stop the "expulsion", the connection between the first gas cylinder 7 and the test chamber can be cut off through a valve.

[0043] The inert gases in the first gas cylinder 7, the second gas cylinder 19 and the third gas cylinder 23 can be inert gases such as N2 or Ar.

[0044] In some embodiments, the solution supply system further includes a third gas cylinder 23 for containing inert gas; an outlet end of the third gas cylinder 23 is communicated with a second pipeline, and one end of the second pipeline is communicated with the upper space (above the solution level) of the solution supply tank 17; the lower space (below the solution level) of the solution supply tank 17 is communicated with the bottom of the test chamber through a liquid inlet pipe.

[0045] In this embodiment, the test solution 18 in the solution supply tank 17 is pressed into the test chamber by the pressurized gas in the third gas cylinder 23. During use, the third gas cylinder 23 is communicated with the solution supply tank 17 through a valve, and the pressurized gas in the third gas cylinder 23 will flow through the second pipeline to the solution supply tank 17. When the pressure reaches a certain level, the test solution 18 will flow into the test chamber under the action of air pressure. The valve is preferably an adjustable valve, and the replenishment rate of the solution is achieved by adjusting the opening degree between the valves.

[0046] An embodiment of the present invention further provides a system for measuring metal electrochemical corrosion in bentonite, including an electrochemical measurement system and a simulation device for the test environment of metal electrochemical corrosion in bentonite as described in the above embodiments. The working electrode of the electrochemical measurement system is made of the candidate material of the disposal container and is used to be buried in the bentonite 2 in the test chamber.

[0047] This embodiment has all the advantages described in the above simulation device for the test environment of metal electrochemical corrosion in bentonite, and will not be elaborated here.

[0048] In some embodiments, the electrochemical measurement system includes a reference electrode 4, an auxiliary electrode 5, an electrochemical workstation 6 and a plurality of working electrodes; the working electrode and the auxiliary electrode 5 form a current loop, and the working electrode and the reference electrode 4 form a voltage loop; the plurality of working electrodes and the auxiliary electrode 5 are sequentially arranged around the reference electrode 4, and the distance between them and the reference electrode 4 is 3-6 cm.

[0049] In this embodiment, a plurality of working electrodes are provided to simulate metal corrosion, and the electrochemical signals on the plurality of working electrodes are respectively obtained and compared by using the electrochemical workstation 6. When the electrochemical signal on a certain working electrode is quite different from other electrochemical signals, it can be determined as an invalid electrode and its data can be discarded, and then the average value of several other working electrodes can be taken. Such a setting can effectively reduce the error in electrochemical testing.

[0050] In some embodiments, a Cu electrode lead with a polytetrafluoroethylene insulating tube and a working electrode specimen block are soldered with tin solder, and the solder joints are sealed with high-temperature glue. The reference electrode 4 is a Pt wire with a polytetrafluoroethylene insulating tube, and the auxiliary electrode 5 is made by arc welding a Pt wire with a polytetrafluoroethylene insulating tube and a Pt sheet. Since the impurity content of the arc-welded joints is less and the same inert metal Pt is welded, the joints can be unsealed. The inert metal Pt as the reference electrode 4 and the auxiliary electrode 5 has high corrosion resistance and maintains high stability in most environments, which can prevent the distortion of the working electrode signal or the failure of the electrode test system caused by corrosion, and ensure the accuracy and stability of the electrochemical signal during long-term testing.

[0051] In some embodiments, such as Figure 2 shown, three working electrodes are provided, namely working electrode one 3, working electrode two 34, and working electrode three 35. To reduce the interference with the voltage and current circuits, the relative positions of the working electrode one 3, working electrode two 34, working electrode three 35, reference electrode 4, and auxiliary electrode 5 are as Figure 2 shown. The working electrode one 3, working electrode two 34, and working electrode three 35 are 3 - 6 cm away from the reference electrode 4, and the distance between the auxiliary electrode 5 and the reference electrode 4 is 3 - 6 cm.

[0052] In some embodiments, the embodiment of the present invention further includes a gas content measurement system. The gas content measurement system is used to detect the gas release amount in the test chamber during the corrosion test. When necessary, the generated gas can also be collected. The corrosion rate of the metal is inferred from the generated gas content and compared with the corrosion rate result measured electrochemically, so as to achieve the purpose of comprehensively evaluating the corrosion behavior of the candidate materials for the disposal container in the simulated repository environment.

[0053] The gas content measurement system can adopt any one of the existing technologies. The present invention specifically provides the following structure. The gas content measurement system in this embodiment includes a precision pressure gauge and a gas collecting pipe. The precision pressure gauge is configured to be able to detect the air pressure in the test chamber. One end of the gas collecting pipe is communicated with the test chamber, and the other end is communicated with the atmosphere. Part of the gas collecting pipe is a downward-bent pipe, and the bent pipe is filled with dimethyl silicone oil 31 to seal the gas collecting pipe. A valve and an exhaust port are provided on the gas collecting pipe between the bent pipe and the test chamber. The gas release amount in the test chamber during the corrosion test is calculated by the displacement of the dimethyl silicone oil 31 under the action of air pressure.

[0054] Specifically, the gas content measurement system includes a precision pressure gauge 27, a boring tube 28, a first ventilation valve 29, a second ventilation valve 30, dimethyl silicone oil 31, a reference line 32, and a third exhaust valve 33. The precision pressure gauge 27 is used to measure the gas pressure of the entire electrochemical test system. The boring tube 28 is a transparent precision boring tube 28 with a U-bend and an inner diameter of 2 mm, which is used to measure the generated gas content. The first ventilation valve 29 and the second ventilation valve 30 are used to achieve gas conduction. The dimethyl silicone oil 31 with a relatively low saturated vapor pressure is used for liquid sealing of gas at the U-bend of the transparent precision boring tube 28. The reference line 32 is the highest liquid level of the dimethyl silicone oil 31 and is the reference line 32 for measuring the generated gas content. The third exhaust valve 33 is used to collect the generated gas.

[0055] The specific valve settings of the present utility model are as Figure 1 shown.

[0056] The embodiment of the present utility model also provides a method for testing the electrochemical corrosion of metals in bentonite. The test is carried out using the measurement system for electrochemical corrosion of metals in bentonite in the above embodiment, and includes the following steps:

[0057] Step 1: Sample preparation and installation;

[0058] Step 2: Deoxygenation of dry compacted bentonite 2;

[0059] Step 3: Deoxygenation of the test solution 18;

[0060] Step 4: Preparation of saturated anaerobic bentonite 2 by introducing the anaerobic test solution 18 into the anaerobic bentonite 2;

[0061] Step 5: Heating and temperature increase, and collecting the electrochemical signals of the electrochemical test system;

[0062] Step 6: Maintaining the long-term saturation of bentonite 2;

[0063] Step 7: Measurement and collection of gas;

[0064] Step 8: Comprehensive evaluation of the corrosion behavior of the candidate materials for the disposal container.

[0065] Specifically, (1) Sample preparation and installation

[0066] The working electrode specimen block and the electrode lead are soldered, and the solder joints are sealed with high-temperature glue to prepare the first working electrode 3, the second working electrode 34, and the third working electrode 35; the Pt sheet and the Pt wire electrode lead are prepared into the auxiliary electrode 5 by argon arc welding. The bentonite 2 with a certain density is compacted by a uniaxial press and a mold. The first working electrode 3, the second working electrode 34, the third working electrode 35, the reference electrode 4, the auxiliary electrode 5, the first oxygen probe 12, and the temperature and humidity sensor 16 are placed into the dry compacted bentonite 2, and then the compacted bentonite 2 is placed into the metal Ni autoclave and sealed.

[0067] (2) Deoxygenation of the dry compacted bentonite 2

[0068] The first exhaust valve 9 is connected to the liquid seal tank 10 filled with water 11 through a plastic pipe for liquid sealing. The first gas cylinder 7 filled with inert gas such as N2 or Ar, the first intake valve 8, and the first exhaust valve 9 are opened, and the inert gas such as N2 or Ar is introduced into the dry bentonite 2 until the oxygen content displayed by the data acquisition and control system 13 of the first oxygen probe 12 is less than 5 ppb. At this time, the first gas cylinder 7, the first exhaust valve 9, and the first intake valve 8 of the inert gas such as N2 or Ar are closed.

[0069] (3) Deoxygenation of the test solution 18

[0070] The second exhaust valve 21 is connected to the liquid seal tank 10 filled with water 11 through a plastic pipe for liquid sealing. The second gas cylinder 19 filled with inert gas such as N2 or Ar, the second intake valve 20, and the second exhaust valve 21 are opened, and the inert gas such as N2 or Ar is introduced into the test solution 18 in the solution supply tank 17 until the oxygen content displayed by the data acquisition and control system 13 of the second oxygen probe 22 is less than 5 ppb. Then, the second gas cylinder 19, the second intake valve 20, and the second exhaust valve 21 of the inert gas such as N2 or Ar are closed, and the deoxygenation is stopped.

[0071] (4) The anaerobic bentonite 2 is saturated with the anaerobic test solution 18

[0072] The third gas cylinder 23 filled with inert gas such as N2 or Ar, the third intake valve 24, the drain valve 25, the liquid inlet valve 26, and the first exhaust valve 9 are opened. Gas is introduced into the solution supply tank 17 through the third intake valve 24, and a certain gas overpressure is maintained, so that the test solution 18 enters the bentonite 2 through the drain valve 25 and the liquid inlet valve 26. When liquid appears in the first exhaust valve 9, it indicates that the bentonite 2 is saturated. At this time, the third gas cylinder 23, the third intake valve 24, the drain valve 25, the liquid inlet valve 26, and the first exhaust valve 9 of the inert gas such as N2 or Ar are closed.

[0073] (5) Heating and temperature rising, and electrochemical signal acquisition of the electrochemical test system

[0074] The metal Ni kettle is heated and raised in temperature by the heating tape 14, while the heat preservation layer 15 keeps the metal Ni kettle warm. When the data acquisition and control system 13 shows that the temperature and humidity sensor 16 reaches the set temperature, the electrochemical workstation 6 is used to measure the electrochemical signal of the electrode.

[0075] (6) Long-term saturation of bentonite 2

[0076] After the working electrode corrodes for a period of time, when the data acquisition and control system 13 shows that the humidity of the temperature and humidity sensor 16 decreases, open the third gas cylinder 23 of inert gas such as N2 or Ar, the third intake valve 24, the liquid discharge valve 25, the liquid inlet valve 26 and the first exhaust valve 9, and replenish the test solution 18 to the bentonite 2 until the bentonite 2 reaches saturation again, and then close the third gas cylinder 23 of inert gas such as N2 or Ar, the third intake valve 24, the liquid discharge valve 25, the liquid inlet valve 26 and the first exhaust valve 9. Repeating the above process can ensure that the bentonite 2 is always in a saturated state during the long-term test.

[0077] (7) Measurement and collection of gas

[0078] After the working electrode corrodes for a period of time, when there is pressure in the precision pressure gauge 27, it indicates that a certain amount of gas is generated by the corrosion of the working electrode. Open the first ventilation valve 29 and the second ventilation valve 30, observe the height change of the highest liquid level of the dimethyl silicone oil 31 in the precision boring tube 28 relative to the reference line 32, calculate and record the generated gas content. Then close the first ventilation valve 29 and open the third exhaust valve 33 to collect the generated gas.

[0079] (8) Comprehensive evaluation of the corrosion behavior of candidate materials for disposal containers

[0080] Speculate the corrosion rate of the working electrode by measuring the generated gas content, and compare it with the corrosion rate measured electrochemically, and comprehensively evaluate the corrosion behavior of the candidate materials for the disposal container in the simulated disposal repository environment, so as to provide a basis for the material selection and thickness design of the disposal container.

[0081] In the present utility model, specific examples are used to elaborate the principle and implementation manner of the present utility model. The description of the above embodiments is only used to help understand the method and its core idea of the present utility model; at the same time, for those of ordinary skill in the art, according to the idea of the present utility model, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present utility model.

Claims

1. An apparatus for simulating the test environment of metal electrochemical corrosion in bentonite, characterized in that: Comprising: A test chamber for filling and compacting bentonite to restrict the expansion of bentonite after saturation; A heating device for heating the bentonite in the test chamber; An oxygen removal system for removing oxygen from the bentonite in the test chamber and the test solution in the solution supply system; A solution supply system for supplying solution to the bentonite in the test chamber.

2. The device for simulating the metal electrochemical corrosion test environment in bentonite according to claim 1, wherein: The test chamber is formed in a test box made of metal with corrosion resistance and a strength of at least 130 MPa. The heating device includes an electric heating tape that is covered on the outer wall of the test box, and the outer wall of the test box without the electric heating tape is covered with a heat insulation layer.

3. The device for simulating the metal electrochemical corrosion test environment in bentonite according to claim 1, wherein: The oxygen removal system includes a first gas cylinder for containing inert gas and a second gas cylinder for containing inert gas. The outlet of the first gas cylinder is communicated with the bottom of the test chamber, and a discharge port is provided at the top of the test chamber; The solution supply system includes a solution supply tank for containing the test solution. One end of a first pipeline is communicated with the outlet end of the second gas cylinder, and the other end of the first pipeline away from the outlet end of the second gas cylinder extends into the test solution; A second exhaust port is provided at the top of the solution supply tank, and both the discharge port and the second exhaust port are communicated with a liquid seal tank through pipelines.

4. The device for simulating the metal electrochemical corrosion test environment in bentonite according to claim 3, characterized in that: The solution supply system further includes a third gas cylinder for containing inert gas; one end of a second pipeline is communicated with the outlet end of the third gas cylinder, and the other end of the second pipeline is communicated with the upper space of the solution supply tank; the lower space of the solution supply tank is communicated with the bottom of the test chamber through a liquid inlet pipe.

5. A metal electrochemistry corrosion measurement system for bentonite, characterized in that: Comprising an electrochemical measurement system and a simulation device for the electrochemical corrosion test environment of metals in bentonite according to any one of claims 1 to 4. The working electrode of the electrochemical measurement system is made of a candidate material for the disposal container and is used to be buried in the bentonite in the test chamber.

6. The measurement system for metal electrochemical corrosion in bentonite according to claim 5, characterized in that: The electrochemical measurement system includes a reference electrode, an auxiliary electrode, an electrochemical workstation, and a plurality of working electrodes; the working electrode and the auxiliary electrode form a current loop, and the working electrode and the reference electrode form a voltage loop; the plurality of working electrodes and the auxiliary electrode are sequentially arranged around the reference electrode, and the distance between them and the reference electrode is 3 - 6 cm.

7. The measurement system for metal electrochemical corrosion in bentonite according to claim 5, characterized in that: It further includes a gas content measurement system for detecting the gas release amount in the test chamber during the corrosion test.

8. The measurement system for metallic electrochemistry corrosion in bentonite according to claim 7, wherein: The gas content measurement system includes a precision pressure gauge and a gas collecting pipe. The precision pressure gauge is configured to be able to detect the air pressure in the test chamber. One end of the gas collecting pipe is communicated with the test chamber, and the other end is communicated with the atmosphere. Part of the gas collecting pipe is a downward-bent pipe filled with dimethyl silicone oil to seal the gas collecting pipe. A valve and an exhaust port are provided on the gas collecting pipe between the bent pipe and the test chamber. The gas release amount in the test chamber during the corrosion test is calculated by the displacement of the dimethyl silicone oil under the action of air pressure.

9. The measurement system for metal electrochemical corrosion in bentonite according to claim 5, characterized in that: A temperature and humidity sensor and an oxygen probe are buried in the bentonite in the test chamber; an oxygen probe is arranged in the solution supply tank of the solution supply system.

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