A field monitoring device and method for radionuclide migration experiments in an underground laboratory

Abstract

The present invention belongs to the technical field of underground laboratory nuclide migration test, and specifically relates to an underground laboratory nuclide migration test on-site monitoring equipment and method, which is used for underground laboratory nuclide migration test, wherein the equipment is arranged on a borehole at the location of an underground laboratory for deep geological safety disposal of high-level radioactive waste, and comprises a high-pressure plugging system (1) and an underground diffusion device (2), wherein the high-pressure plugging system (1) is used to plug the borehole to ensure the low oxygen reduction state of groundwater in the borehole; and the underground diffusion device (2) is used for diffusion experiment of nuclides in groundwater in a medium. The equipment and method provided by the present invention can be used for long-term monitoring of pH, Eh, conductivity, temperature, and pressure of low oxygen groundwater in a real geological environment, and carry out solubility determination of nuclides in low oxygen groundwater in a real underground environment and long-term diffusion experiment of nuclides, and automatically collect test samples under low oxygen conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of underground laboratory nuclide migration test, and in particular relates to a field monitoring device and method for underground laboratory nuclide migration test. Background Art

[0002] Before the implementation of deep geological disposal of high-level radioactive waste, it is necessary to conduct safety analysis and evaluation of the pre-selected site and deep geological disposal repository. The construction of underground laboratories and field tests can provide the most direct technical and experience support for the design, construction, operation and safety evaluation analysis of deep geological disposal repositories. Nuclide migration is one of the core issues in the safe deep geological disposal of high-level radioactive waste. At the underground laboratory site, conducting nuclide migration research is a necessary stage in geological disposal projects. The development of field monitoring equipment and methods for nuclide migration tests in underground laboratories makes it possible to conduct on-site monitoring and collection of groundwater and nuclide migration tests in real underground environments. The data obtained will provide a scientific basis for the safety evaluation of deep geological disposal repositories. At present, there are no such equipment and methods in China. Sweden's SKB once led the development of the Chemical Test Chamber (CHEMLAB) and used it in The test results of the hard rock underground laboratory were not satisfactory. The main reasons were:

[0003] 1) There is no high-pressure plugging system, resulting in groundwater leakage and damage to electronic components and valves;

[0004] 2) Oxygen was not removed before the experiment, resulting in oxidation of Fe(II) in the groundwater to Fe(III) and formation of precipitation;

[0005] 3) If the pipeline is not cleaned and emptied in time, it may cause crystallization blockage;

[0006] 4) Eh and pH electrodes are immersed in groundwater for a long time and cannot be calibrated regularly, resulting in inaccurate monitoring data. Summary of the invention

[0007] The purpose of the present invention is to provide a device that can monitor the pH, Eh, conductivity, temperature, and pressure of groundwater in a real underground environment for a long time, and carry out a migration test of nuclides in real groundwater in a medium, and automatically collect test samples under low oxygen conditions.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is a field monitoring equipment for underground laboratory nuclide migration test, which is used for underground laboratory nuclide migration test and is arranged on the borehole where the underground laboratory for deep geological safety disposal of high-level radioactive waste is located, and includes a high-pressure plugging system and an underground diffusion device. The high-pressure plugging system is used to plug the borehole to ensure the low-oxygen reduction state of the groundwater in the borehole; the underground diffusion device is used for the diffusion experiment of the nuclides in the groundwater in the medium.

[0009] Furthermore, the high-pressure plugging system is connected to the underground diffusion device through a first pipeline, and the high-pressure plugging system and the underground diffusion device are both arranged in an experimental pipe warehouse, and the experimental pipe warehouse is arranged inside the borehole and the high-pressure plugging system and the underground diffusion device cannot be replaced, constituting the inner part of the borehole; the high-pressure plugging system is provided with a pair of plugs, and also includes a ninth pipeline, one end of the ninth pipeline is connected to the plug, and the other end of the ninth pipeline is connected to a high-pressure water pump, and the ninth pipeline is used to pass high-pressure circulating water into the plug, so that the embolism blocks the borehole through the high-pressure circulating water, and the high-pressure circulating water in the plug maintains a water pressure of 40MPa.

[0010] Furthermore, it also includes an underground dissolution device, the high-pressure plugging system is connected to the underground dissolution device through a second pipeline, and the underground diffusion device is connected to the underground dissolution device through an eighth pipeline; the underground dissolution device is used to carry out radionuclide dissolution experiments in the groundwater.

[0011] Furthermore, it also includes a collection system, which is connected to the high-pressure plugging system through a fourth pipeline, and is connected to the underground dissolution device through a seventh pipeline. The collection system is used to collect water samples of the groundwater.

[0012] Furthermore, it also includes a tracer injection device, which is connected to the collection system through a fifth pipeline, and is connected to the underground diffusion device through a sixth pipeline. The tracer injection device is used to inject radionuclides into the underground diffusion device and the underground dissolution device.

[0013] Furthermore, it also includes a groundwater collection and monitoring system, which is connected to the high-pressure plugging system through a third pipeline, and the groundwater collection and monitoring system is used for monitoring and collecting the groundwater.

[0014] Furthermore, it also includes a control system for controlling the high-pressure plugging system, the underground diffusion device, the tracer injection device, the underground dissolution device, the collection system and the groundwater collection and monitoring system; pumps and valves are provided on each pipeline, and the control system is also used to remotely control the switching of the pumps and the valves and the pressure and flow of the groundwater and high-purity argon in the pipeline; the high-purity nitrogen is used to drive out the oxygen in the pipeline and in the container arranged on the pipeline, and is also used to blow dry the residual liquid in the pipeline after sampling; the high-purity nitrogen refers to nitrogen with a purity of 99.99%; the pipeline includes the first pipeline, the second pipeline, the third pipeline, the fourth pipeline, the fifth pipeline, the sixth pipeline, the seventh pipeline, the eighth pipeline and the ninth pipeline.

[0015] Furthermore, the tracer injection device, the underground dissolution device, the collection system, the groundwater collection and monitoring system and the control system are all arranged outside the borehole and can be replaced, constituting the outer part of the borehole.

[0016] To achieve the above objectives, the present invention also discloses an underground laboratory nuclide migration test on-site monitoring method for the underground laboratory nuclide migration test on-site monitoring device as described above, comprising the following steps:

[0017] Step S1, removing oxygen: inserting the installed borehole inner part of the underground laboratory nuclide migration test field monitoring equipment into the borehole containing the groundwater, and using the control system to introduce high-purity nitrogen into the borehole inner part to remove the air inside the borehole inner part;

[0018] Step S2, high-pressure plugging and sealing, and leading out and monitoring the groundwater: using the high-pressure plugging system provided with the plug to seal the groundwater in the experimental tube warehouse, and using the control system to allow the groundwater in the experimental tube warehouse to directly enter the groundwater collection and monitoring system for monitoring and collection;

[0019] Step S3, groundwater infiltration: using the control system to adjust the valve and the pump, so that the groundwater infiltrates through the underground diffusion device and enters the collection system;

[0020] Step S4, tritium water injection and sampling: after the groundwater penetrates the underground diffusion device and reaches the collection system, the control system is used to control the tracer injection device to inject tritium water into the underground diffusion device, and the groundwater in the underground diffusion device is sampled through the collection system to measure the activity of tritium in the groundwater;

[0021] Step S5, tritium water diffusion and sampling: using the control system to close the corresponding valves to allow the tritium water to diffuse statically in the underground diffusion device, using the control system and the collection system to periodically sample the groundwater in the underground diffusion device, measure the activity of tritium in the groundwater, and calculate the diffusion coefficient of the tritium water;

[0022] Step S6, dissolution balance and sampling: adding a nuclide solid phase into the underground dissolution device, using the control system to drive the groundwater into the underground dissolution device, using the supersaturation method to perform a dissolution experiment, regularly sampling the groundwater in the underground dissolution device through the collection system, measuring the nuclide activity in the groundwater, and calculating the nuclide solubility;

[0023] Step S7, nuclide injection and sampling: after the tritium water diffusion experiment in step S5 is completed and after the nuclide dissolution equilibrium in step S6 is reached, the nuclide solution in the underground dissolution device is injected into the underground diffusion device using the control system, and the groundwater in the underground diffusion device is sampled regularly by the collection system to measure the activity of the nuclides in the groundwater in the underground diffusion device;

[0024] Step S8, nuclide diffusion and sampling: the control system is used to close the corresponding valves to allow the nuclide solution to diffuse statically in the underground diffusion device. The control system and the collection system periodically sample the groundwater in the underground diffusion device, measure the activity of the nuclides in the groundwater in the underground diffusion device, and calculate the diffusion coefficient of the nuclides.

[0025] The beneficial effects of the present invention are:

[0026] 1. The equipment and method provided by the present invention can be used for long-term monitoring of pH, Eh, conductivity, temperature, and pressure of hypoxic groundwater in a real geological environment, and to carry out solubility determination of nuclides in hypoxic groundwater in a real underground environment and long-term diffusion test of nuclides, and automatically collect test samples under hypoxic conditions.

[0027] 2. The device provided by the present invention is in the shape of an elongated cylinder and matches the borehole in the underground laboratory, and is suitable for long-term monitoring and experimental research in the underground laboratory. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of a field monitoring device for underground laboratory nuclide migration test described in a specific embodiment of the present invention;

[0029] In the figure: 1-high pressure plugging system, 2-underground diffusion device, 3-tracer injection device, 4-underground dissolution device, 5-collection system, 6-groundwater collection and monitoring system, 7-control system, 8-first pipeline, 9-second pipeline, 10-third pipeline, 11-fourth pipeline, 12-fifth pipeline, 13-sixth pipeline, 14-seventh pipeline, 15-eighth pipeline, 16-ninth pipeline. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] like Figure 1As shown, the present invention provides an underground laboratory nuclide migration test field monitoring equipment (referred to as "field monitoring equipment"), which is used for underground laboratory nuclide migration tests and is arranged on a borehole at the location of an underground laboratory for deep geological safety disposal of high-level radioactive waste, wherein the equipment includes a high-pressure plugging system 1 and an underground diffusion device 2. The high-pressure plugging system 1 is used to plug the borehole to prevent air infiltration to ensure the low-oxygen reduction state of groundwater in the borehole, and at the same time, it can also prevent equipment damage caused by groundwater leakage; the underground diffusion device 2 is used for diffusion experiments of nuclides in groundwater in a medium.

[0032] The high-pressure plugging system 1 is connected to the underground diffusion device 2 through the first pipeline 8. The high-pressure plugging system 1 and the underground diffusion device 2 are both arranged in the experimental pipe warehouse. The experimental pipe warehouse is arranged inside the borehole and the high-pressure plugging system 1 and the underground diffusion device 2 cannot be replaced, constituting the borehole part of the field monitoring equipment, and the outer diameter of this part is 95 mm; the high-pressure plugging system 1 is provided with a pair of embolic plugs (made of natural rubber), and the embolic plugs are provided with a ninth pipeline 16, and the ninth pipeline 16 is used to pass high-pressure circulating water into the embolic plugs (one end of the ninth pipeline 16 is connected to the embolic plug, and the other end of the ninth pipeline 16 is connected to the high-pressure water pump). The embolic plugs the borehole through the high-pressure circulating water (pressure of 40MPa), so that the groundwater (deep groundwater) in the borehole is completely and strictly sealed for a long time and completely isolated from the air, ensuring that the groundwater in the borehole is maintained in a low-oxygen reduction state. At the same time, it can also avoid equipment damage caused by groundwater leakage and prevent the metal components and valves of the field monitoring equipment from being corroded by groundwater.

[0033] It also includes an underground dissolution device 4. The high-pressure plugging system 1 is connected to the underground dissolution device 4 through a second pipeline 9, and the underground diffusion device 2 is connected to the underground dissolution device 4 through an eighth pipeline 15; the underground dissolution device 4 is used to carry out radionuclide dissolution experiments in groundwater.

[0034] It also includes a collecting system 5, which is connected to the high-pressure plugging system 1 through a fourth pipeline 11, and is connected to the underground dissolution device 4 through a seventh pipeline 14. The collecting system 5 is used to collect groundwater samples.

[0035] It also includes a tracer injection device 3, which is connected to the collection system 5 through a fifth pipeline 12, and is connected to the underground diffusion device 2 through a sixth pipeline 13. The tracer injection device 3 is used to quantitatively inject radionuclides into the underground diffusion device 2 and the underground dissolution device 4.

[0036] It also includes a groundwater collection and monitoring system 6, which is connected to the high-pressure plugging system 1 through a third pipeline 10. The groundwater collection and monitoring system 6 is used for monitoring and collecting groundwater.

[0037] It also includes a control system 7 for controlling the high-pressure plugging system 1, the underground diffusion device 2, the tracer injection device 3, the underground dissolution device 4, the collection system 5 and the groundwater collection and monitoring system 6; pumps and valves are provided on each pipeline, and the control system 7 is also used to remotely control the switching of the pumps and valves and the pressure and flow of groundwater and high-purity argon in the pipeline; high-purity nitrogen is used to drive out oxygen in the pipeline and in the container arranged on the pipeline, and is also used to blow dry the residual liquid in the pipeline after sampling; high-purity nitrogen refers to nitrogen with a purity of 99.99%; the pipelines include a first pipeline 8, a second pipeline 9, a third pipeline 10, a fourth pipeline 11, a fifth pipeline 12, a sixth pipeline 13, a seventh pipeline 14, an eighth pipeline 15 and a ninth pipeline 16.

[0038] The tracer injection device 3, underground dissolution device 4, collection system 5, groundwater collection monitoring system 6 and control system 7 are all arranged outside the borehole and can be replaced, constituting the outer borehole part of the field monitoring equipment.

[0039] The present invention also provides an underground laboratory nuclide migration test on-site monitoring method for the underground laboratory nuclide migration test on-site monitoring device as described above, comprising the following steps:

[0040] Step S1, removing oxygen: inserting the installed borehole inner part of the underground laboratory nuclide migration test field monitoring equipment into the borehole containing groundwater, and using the control system 7 to introduce high-purity nitrogen into the borehole inner part to remove the air inside the borehole inner part;

[0041] Step S2, high-pressure plugging and sealing, and leading out and monitoring groundwater: using a high-pressure plugging system 1 with an embolism (double embolism) to seal the groundwater in the experimental pipe chamber, and using a control system 7 to allow the groundwater in the experimental pipe chamber to directly enter the groundwater collection and monitoring system 6 for monitoring and collection;

[0042] Step S3, groundwater infiltration: using the control system 7 to adjust the valves and pumps, so that the groundwater slowly infiltrates through the underground diffusion device 2 and enters the collection system 5;

[0043] Step S4, tritium water injection and sampling: after the groundwater penetrates the underground diffusion device 2 and reaches the collection system 5, the control system 7 is used to control the tracer injection device 3 to inject tritium water into the underground diffusion device 2, and the groundwater in the underground diffusion device 2 is sampled through the collection system 5 to measure the activity of tritium in the groundwater;

[0044] Step S5, diffusion and sampling of tritium water: using the control system 7 to close the corresponding valves, so that the tritium water is statically diffused in the underground diffusion device 2, and using the control system 7 and the collection system 5 to regularly sample the groundwater in the underground diffusion device 2, measure the activity of tritium in the groundwater, and calculate the diffusion coefficient of the tritium water;

[0045] Step S6, dissolution balance and sampling: adding a nuclide solid phase to the underground dissolution device 4, using the control system 7 to drive groundwater into the underground dissolution device 4, using the supersaturation method to perform a dissolution experiment, and regularly sampling the groundwater in the underground dissolution device 4 through the collection system 5 to measure the nuclide activity in the groundwater and calculate the nuclide solubility;

[0046] Step S7, nuclide injection and sampling: after the tritium water diffusion experiment in step S5 is completed and the nuclide dissolution equilibrium in step S6 is reached, the nuclide solution in the underground dissolution device 4 (i.e., the groundwater containing nuclides in the underground dissolution device 4) is injected into the underground diffusion device 2 by using the control system 7, and the groundwater in the underground diffusion device 2 is sampled regularly by the collection system 5 to measure the activity of the nuclides in the groundwater in the underground diffusion device 2;

[0047] Step S8, nuclide diffusion and sampling: use the control system 7 to close the corresponding valves to allow the nuclide solution to diffuse statically in the underground diffusion device 2, control the system 7 and the collection system 5 to regularly sample the groundwater in the underground diffusion device 2, measure the activity of the nuclides in the groundwater in the underground diffusion device 2, and calculate the diffusion coefficient of the nuclides.

[0048] The device described in the present invention is not limited to the embodiments described in the specific implementation manner. Those skilled in the art may derive other implementation manners based on the technical solution of the present invention, which also fall within the technical innovation scope of the present invention.

Claims

1. An underground laboratory nuclide migration test on-site monitoring equipment, used for underground laboratory nuclide migration test, installed on the borehole where the underground laboratory for deep geological safety disposal of high-level radioactive waste is located, characterized by: It comprises a high-pressure plugging system (1) and an underground diffusion device (2), wherein the high-pressure plugging system (1) is used to plug the borehole to ensure the low-oxygen reduction state of groundwater in the borehole; The underground diffusion device (2) is used for diffusion experiments of nuclides in the groundwater in the medium; The high-pressure plugging system (1) is connected to the underground diffusion device (2) via a first pipeline (8); the high-pressure plugging system (1) and the underground diffusion device (2) are both arranged in an experimental pipe warehouse, the experimental pipe warehouse is arranged inside the borehole and the high-pressure plugging system (1) and the underground diffusion device (2) cannot be replaced, constituting the inner part of the borehole; the high-pressure plugging system (1) is provided with a pair of plugs, and also includes a ninth pipeline (16), one end of the ninth pipeline (16) is connected to the plug, and the other end of the ninth pipeline (16) is connected to a high-pressure water pump, the ninth pipeline (16) is used to pass high-pressure circulating water into the plug, so that the plug blocks the borehole through the high-pressure circulating water, and the high-pressure circulating water in the plug maintains a water pressure of 40 MPa; It also includes an underground dissolution device (4), wherein the high-pressure plugging system (1) is connected to the underground dissolution device (4) via a second pipeline (9), and the underground diffusion device (2) is connected to the underground dissolution device (4) via an eighth pipeline (15); the underground dissolution device (4) is used to carry out a radionuclide dissolution experiment in the groundwater; It also includes a collection system (5), the collection system (5) is connected to the high-pressure plugging system (1) via a fourth pipeline (11), the collection system (5) is connected to the underground dissolution device (4) via a seventh pipeline (14), and the collection system (5) is used to collect water samples of the groundwater; It also comprises a tracer injection device (3), the tracer injection device (3) is connected to the collection system (5) via a fifth pipeline (12), the tracer injection device (3) is connected to the underground diffusion device (2) via a sixth pipeline (13), and the tracer injection device (3) is used to inject nuclides into the underground diffusion device (2) and the underground dissolution device (4); It also includes a groundwater collection and monitoring system (6), the groundwater collection and monitoring system (6) being connected to the high-pressure plugging system (1) via a third pipeline (10), the groundwater collection and monitoring system (6) being used for monitoring and collecting the groundwater; It also includes a control system (7) for controlling the high-pressure plugging system (1), the underground diffusion device (2), the tracer injection device (3), the underground dissolution device (4), the collection system (5) and the groundwater collection and monitoring system (6); pumps and valves are provided on each pipeline, and the control system (7) is also used to remotely control the switching of the pumps and valves and the pressure and flow rate of the groundwater and high-purity nitrogen in the pipeline; the high-purity nitrogen is used to drive out the oxygen in the pipeline and in the container arranged on the pipeline, and is also used to blow dry the residual liquid in the pipeline after sampling; the high-purity nitrogen refers to nitrogen with a purity of 99.99%.

2. The underground laboratory nuclide migration test on-site monitoring equipment according to claim 1, characterized in that: The tracer injection device (3), the underground dissolution device (4), the collection system (5), the groundwater collection and monitoring system (6) and the control system (7) are all arranged outside the borehole and are replaceable, constituting the outer part of the borehole.

3. A method for monitoring the underground laboratory nuclide migration test on-site for the underground laboratory nuclide migration test on-site monitoring device as claimed in claim 2, comprising the following steps: Step S1, removing oxygen: inserting the installed borehole inner part of the underground laboratory nuclide migration test field monitoring equipment into the borehole containing the groundwater, and using the control system (7) to introduce high-purity nitrogen into the borehole inner part to remove the air inside the borehole inner part; Step S2, high-pressure plugging and sealing, and leading out and monitoring the groundwater: using the high-pressure plugging system (1) provided with the plug to seal the groundwater in the experimental tube chamber, and using the control system (7) to allow the groundwater in the experimental tube chamber to directly enter the groundwater collection and monitoring system (6) for monitoring and collection; Step S3, groundwater infiltration: using the control system (7) to adjust the valve and the pump, so that the groundwater infiltrates through the underground diffusion device (2) and enters the collection system (5); Step S4, tritium water injection and sampling: after the groundwater penetrates the underground diffusion device (2) and reaches the collection system (5), the control system (7) is used to control the tracer injection device (3) to inject tritium water into the underground diffusion device (2), and the groundwater in the underground diffusion device (2) is sampled through the collection system (5) to measure the activity of tritium in the groundwater; Step S5, diffusion and sampling of tritium water: using the control system (7) to close the corresponding valves, so that the tritium water is statically diffused in the underground diffusion device (2), using the control system (7) and the collection system (5), regularly sampling the groundwater in the underground diffusion device (2), measuring the activity of tritium in the groundwater, and calculating the diffusion coefficient of the tritium water; Step S6, dissolution balance and sampling: adding a nuclide solid phase into the underground dissolution device (4), using the control system (7) to drive the groundwater into the underground dissolution device (4), using the supersaturation method to perform a dissolution experiment, and using the collection system (5) to periodically sample the groundwater in the underground dissolution device (4), measuring the nuclide activity in the groundwater, and calculating the nuclide solubility; Step S7, nuclide injection and sampling: after the tritium water diffusion experiment in step S5 is completed and the nuclide dissolution equilibrium in step S6 is reached, the control system (7) is used to inject the nuclide solution in the underground dissolution device (4) into the underground diffusion device (2), and the groundwater in the underground diffusion device (2) is sampled regularly through the collection system (5) to measure the activity of the nuclides in the groundwater in the underground diffusion device (2); Step S8, nuclide diffusion and sampling: the control system (7) is used to close the corresponding valves to allow the nuclide solution to diffuse statically in the underground diffusion device (2); the control system (7) and the collection system (5) are used to regularly sample the groundwater in the underground diffusion device (2), measure the activity of the nuclides in the groundwater in the underground diffusion device (2), and calculate the diffusion coefficient of the nuclides.

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