System and method for removing radioactive tritium from inert gas

Abstract

The invention provides a system and a method for removing radioactive tritium from inert gas. The system comprises: a filter unit for removing organic components and inorganic particles in the inert gas; the gas buffer tank is used for mixing oxygen and inert gas from the filtering unit; the oxygen supply unit is used for supplying oxygen into the gas buffer tank; the catalytic oxidation unit is used for converting element-state tritium contained in the inert gas into tritiated water; the catalytic washing unit is used for transferring radioactive tritium contained in the inert gas from the catalytic oxidation unit into liquid-phase water; the natural water supply unit is used for supplying natural water into the catalytic washing unit; and the condensing unit is used for condensing the tritium-removed inert gas flowing out of the catalytic washing unit. According to the system and the method, the residual quantity of tritium in the inert gas can be effectively reduced, so that the inert gas reaches the safe emission standard.

Description

Technical Field

[0001] This application relates to the field of nuclear waste treatment technology, and in particular to a system and method for removing radioactive tritium from an inert gas. Background Technology

[0002] Tritium is a radioactive hydrogen isotope with a relatively long half-life (approximately 12.3 years). Its beta decay produces low-energy beta particles that can cause radiation damage to human tissues. In nuclear facilities, the nuclear fuel cycle, and related research, tritium may exist in gaseous form within inert gases. If leaked into the environment, it can enter the human body through the respiratory tract and skin, posing a potential threat to ecosystems and human health. Tritium's chemical properties are similar to ordinary hydrogen, and it exhibits strong mobility, easily penetrating various materials and media. During the operation and maintenance of nuclear facilities, even with strict protective measures, tritium can still enter the inert gas environment through diffusion and infiltration, such as in glove boxes and reactor cooling systems. With the development of nuclear energy technology, the operation and decommissioning of nuclear facilities will generate large amounts of tritium-containing inert gases. For example, the use and generation of tritium are unavoidable in nuclear fuel reprocessing and nuclear fusion experimental devices. Therefore, efficiently and safely removing tritium from inert gases is a crucial aspect of ensuring the sustainable development of the nuclear industry. Current tritium removal technologies still need to be improved in terms of efficiency, especially when dealing with inert gases containing low concentrations of tritium. More efficient removal processes and materials need to be developed to reduce the amount of tritium remaining in inert gases and ensure that they meet safe emission standards.

[0003] Existing tritium removal technologies often require complex equipment and incur high operating costs, limiting their widespread application. Researching low-cost removal materials and processes is crucial for large-scale applications. During tritium removal, secondary pollution to the environment should be minimized. For example, the use of environmentally harmful chemical reagents should be avoided, and green, environmentally friendly removal technologies should be developed to make the entire removal process more in line with sustainable development requirements.

[0004] Therefore, there is a need for an efficient technology to remove radioactive tritium from inert gases in order to reduce the amount of tritium remaining in inert gases and make it meet safe emission standards. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a system and method for removing radioactive tritium from an inert gas. This system can effectively reduce the residual amount of tritium in the inert gas, bringing it up to safe emission standards.

[0006] The first aspect of this application provides a system for removing radioactive tritium from an inert gas, the system comprising: A filtration unit is used to remove organic components and inorganic particles from the inert gas; A catalytic oxidation unit, connected to the filtration unit, is used to convert elemental tritium contained in an inert gas into tritium water. The catalytic oxidation unit is equipped with a catalytic reactor, which is filled with a noble metal catalyst and a first packing material. A gas buffer tank is disposed between and connected to the filtration unit and the catalytic oxidation unit for mixing oxygen and an inert gas from the filtration unit. An oxygen supply unit, which is connected to the gas buffer tank, is used to supply oxygen to the gas buffer tank; A catalytic washing unit, connected to the catalytic oxidation unit, is used to transfer radioactive tritium contained in the inert gas from the catalytic oxidation unit to liquid water. The catalytic washing unit is provided with a catalytic washing reaction column, wherein the catalytic washing reaction column is filled with a noble metal hydrophobic catalyst and a second packing material, the second packing material being hydrophilic, and a gas saturator is provided at the bottom of the catalytic washing reaction column to ensure that the inert gas flowing from the catalytic oxidation unit into the catalytic washing reaction column contains saturated water vapor. A natural water supply unit, connected to the catalytic washing unit, is used to supply natural water to the catalytic washing reaction column of the catalytic washing unit. The natural water is in convective contact with inert gas supplied to the catalytic washing reaction column from the catalytic oxidation unit. A condensation unit, connected to the catalytic washing unit, is used to condense the inert gas after tritium removal flowing out of the catalytic washing unit.

[0007] In some embodiments, the noble metal hydrophobic catalyst packed in the catalytic washing reaction column is selected from one or more platinum-based (Pt) catalysts.

[0008] In some embodiments, the noble metal catalyst packed in the catalytic reactor is selected from one or more palladium-Pd based catalysts.

[0009] In some embodiments, the first packing and the second packing are each independently selected from one or more of bulk packing or structured packing.

[0010] In some embodiments, the catalytic oxidation unit further includes a cooling subunit disposed around the catalytic reactor for removing the heat released by the catalytic reaction.

[0011] In some embodiments, the catalytic washing unit further includes a heat-insulating subunit disposed around the catalytic washing reaction column for providing a constant reaction temperature to the catalytic washing reaction column.

[0012] In some embodiments, the system further includes a gas preheating unit disposed between and connected to the gas buffer tank and the catalytic oxidation unit, for preheating the inert gas from the gas buffer tank.

[0013] In some embodiments, the system further includes a gas circulation unit disposed between and connected to the catalytic oxidation unit and the gas buffer tank, for circulating inert gas flowing from the catalytic oxidation unit back to the gas buffer tank.

[0014] In some embodiments, the system further includes a storage unit connected to the catalytic washing unit for storing tritium-containing water (HTO) flowing out of the catalytic washing unit.

[0015] A second aspect of this application provides a method for removing radioactive tritium from an inert gas, the method comprising the following steps: S1: The inert gas is filtered to remove organic components and inorganic particles; S2: Mix the inert gas filtered in step S1 with oxygen; S3: In the presence of a noble metal catalyst, the inert gas mixed with oxygen in step S2 is subjected to an oxidation reaction to convert the elemental tritium contained in the inert gas into water tritide. S4: In the presence of a noble metal-based hydrophobic catalyst, the inert gas that has undergone step S3 is brought into convective contact with natural water to transfer the radioactive tritium contained in the inert gas to the liquid water, resulting in tritium-containing water and a tritium-free inert gas; and S5: Condense the inert gas from which tritium has been removed generated in step S4.

[0016] In some embodiments, in step S4, the noble metal hydrophobic catalyst is selected from one or more platinum-based catalysts.

[0017] In some embodiments, in step S3, the noble metal catalyst is selected from one or more palladium-Pd based catalysts.

[0018] In some embodiments, the method further includes a step of preheating the inert gas mixed with oxygen in step S2 to 60°C to 75°C before performing step S3.

[0019] In some embodiments, the method further includes a step of recovering the tritium-containing water generated in step S4.

[0020] In some embodiments, the method further includes: recycling the inert gas that has undergone step S3 to step S2 to mix with the oxygen in step S2, and then performing the oxidation reaction in step S3 again.

[0021] The system and method for removing radioactive tritium from an inert gas according to this application have the following advantages: 1. It can simultaneously and deeply remove radioactive tritium in both elemental and oxidized states from inert gases; 2. It can efficiently convert elemental tritium into oxidized tritium water; 3. Deep removal of elemental and oxidized radioactive tritium through a catalytic washing process; 4. It can handle a wide range of tritium concentrations, including both elemental and oxidized tritium. 5. The catalytic washing process uses catalytic exchange to convert tritium in its elemental state into its oxidized state. Attached Figure Description

[0022] Figure 1 A schematic diagram of a system for removing radioactive tritium from an inert gas according to an embodiment of this application is shown.

[0023] Figure 2 A flowchart illustrating a method for removing radioactive tritium from an inert gas according to an embodiment of this application is shown.

[0024] Explanation of reference numerals in the attached figures: 1: Filtration unit; 2: Gas buffer tank; 3: Catalytic oxidation unit; 4: Catalytic washing unit; 5: Condensation unit; 6: Storage unit; 7: Gas circulation unit. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the implementation methods of this application. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0026] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In the event of any conflict, this specification shall prevail.

[0027] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or method that comprises a list of elements includes not only the elements expressly stated, but also other elements not expressly listed, or elements inherent to implementing the product, method, apparatus, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other related elements in the product or method that includes that element.

[0028] In this paper, the expression "unit A is connected to unit B" means, unless otherwise specified, that the two can be directly connected or indirectly connected through one or more intermediate units.

[0029] With the development of nuclear energy technology, large amounts of tritium-containing inert gases are generated during the operation and decommissioning of nuclear facilities. For example, the use and generation of tritium are unavoidable in nuclear fuel reprocessing and nuclear fusion experimental devices. How to efficiently and safely remove tritium from inert gases is a crucial aspect of ensuring the sustainable development of the nuclear industry. Current tritium removal technologies still need improvement in efficiency, especially when handling inert gases with low concentrations of tritium.

[0030] Therefore, there is a need for an efficient technology to remove radioactive tritium from inert gases in order to reduce the amount of tritium remaining in inert gases and make it meet safe emission standards.

[0031] In view of this, a first aspect of this application provides a system for removing radioactive tritium from an inert gas, the system comprising: A filtration unit is used to remove organic components and inorganic particles from the inert gas; A catalytic oxidation unit, connected to the filtration unit, is used to convert elemental tritium contained in an inert gas into tritium water. The catalytic oxidation unit is equipped with a catalytic reactor, which is filled with a noble metal catalyst and a first packing material. A gas buffer tank is disposed between and connected to the filtration unit and the catalytic oxidation unit for mixing oxygen and an inert gas from the filtration unit. An oxygen supply unit, which is connected to the gas buffer tank, is used to supply oxygen to the gas buffer tank; A catalytic washing unit, connected to the catalytic oxidation unit, is used to transfer radioactive tritium contained in the inert gas from the catalytic oxidation unit to liquid water. The catalytic washing unit is provided with a catalytic washing reaction column, wherein the catalytic washing reaction column is filled with a noble metal hydrophobic catalyst and a second packing material, the second packing material being hydrophilic, and a gas saturator is provided at the bottom of the catalytic washing reaction column to ensure that the inert gas flowing from the catalytic oxidation unit into the catalytic washing reaction column contains saturated water vapor. A natural water supply unit, connected to the catalytic washing unit, is used to supply natural water to the catalytic washing reaction column of the catalytic washing unit. The natural water is in convective contact with inert gas supplied to the catalytic washing reaction column from the catalytic oxidation unit. A condensation unit, connected to the catalytic washing unit, is used to condense the inert gas after tritium removal flowing out of the catalytic washing unit.

[0032] Figure 1 The diagram shows a schematic representation of a system for removing radioactive tritium from an inert gas according to an embodiment of this application. Figure 1 As shown, the system for removing radioactive tritium from an inert gas according to this application includes a filtration unit 1, a gas buffer tank 2, an oxygen supply unit (not shown), a catalytic oxidation unit 3, a catalytic washing unit 4, a natural water supply unit (not shown), and a condensation unit 5. The inert gas containing radioactive tritium first passes through the filtration unit 1 and then enters the gas buffer tank 2, where it mixes with oxygen from the oxygen supply unit before entering the catalytic oxidation unit 3. In the catalytic oxidation unit 3, elemental tritium (HT) is oxidized to water tritide (HTO). At this point, the radioactive tritium mainly leaves the catalytic oxidation unit as water tritide vapor along with the inert gas. The inert gas leaving the catalytic oxidation unit enters the catalytic washing unit 4, where the radioactive tritium is transferred to liquid water through a dual action of catalysis and washing, achieving deep removal of tritium from the inert gas. The tritium content in the inert gas after removal meets emission requirements, and it can be directly discharged after condensation in the condensation unit 5.

[0033] The filtration unit 1 is used to remove organic components such as oils and particulate impurities such as inorganic particles from the inert gas. For example, the filtration unit may include porous adsorbents such as activated carbon, molecular sieves, carbon fibers, and metal-organic framework materials, which remove organic components and inorganic particles from the inert gas through adsorption.

[0034] Catalytic oxidation unit 3 is used to convert elemental tritium contained in the inert gas into water tritide. Elemental tritium, also known as tritium-containing hydrogen gas, can be represented as HT. Within the catalytic oxidation unit, tritium-containing hydrogen gas undergoes a hydrogen-oxygen complexation reaction with oxygen under the action of a noble metal catalyst, as shown below, converting elemental tritium HT into vaporized water tritide HTO: .

[0035] A gas buffer tank 2 is disposed between and connected to both the filter unit 1 and the catalytic oxidation unit 3. The gas buffer tank receives filtered inert gas from the filter unit. Furthermore, the gas buffer tank is also connected to an oxygen supply unit to receive oxygen from the oxygen supply unit. In the gas buffer tank, the filtered inert gas from the filter unit and the oxygen from the oxygen supply unit are mixed and then supplied to the aforementioned catalytic oxidation unit.

[0036] An oxygen supply unit is connected to a gas buffer tank to supply oxygen to the tank. In the gas buffer tank, oxygen is mixed with an inert gas to provide the necessary oxygen for the hydrogen-oxygen recombination reaction in the catalytic oxidation unit, thereby promoting the reaction towards water tritium (HTO). In this document, the terms "catalytic oxidation reaction," "oxidation reaction," and "hydrogen-oxygen recombination reaction" have the same meaning and can be used interchangeably.

[0037] The catalytic washing unit 4 is the core unit of the system in this application. A catalytic washing reaction column is provided within the catalytic washing unit. The catalytic washing reaction column is filled with a noble metal-based hydrophobic catalyst and a second packing material, which is a hydrophilic packing material. Inert gas flowing out of the catalytic oxidation unit is introduced into the catalytic washing unit, particularly the catalytic washing reaction column. In the inert gas flowing out of the catalytic oxidation unit, tritium mainly exists in the form of vaporized water tritide (HTO) and a lower content of elemental tritium (HT). Within the catalytic washing unit, particularly within the catalytic washing reaction column, HT is converted into the liquid aqueous phase through a catalytic exchange reaction. Specifically, under the action of the noble metal-based hydrophobic catalyst, HT reacts with natural water (H2O) introduced into the catalytic washing reaction column as follows: .

[0038] Furthermore, within the catalytic washing unit, particularly within the catalytic washing reaction column, vaporized water tritium (HTO) will exchange with natural water (H2O) and be transferred to the liquid aqueous phase, as shown in the following formula: .

[0039] Through the two-step reaction described above, tritium in HT is transferred to the liquid phase, thereby achieving the goal of further removing tritium from the inert gas. The inert gas after tritium removal meets the emission requirements and can be directly discharged. The tritium enriched in the liquid water can undergo further treatment.

[0040] A natural water supply unit is connected to a catalytic washing unit. Natural water from the natural water supply unit flows downwards from the top of the catalytic washing reaction column, while tritium-containing inert gas from the catalytic oxidation unit flows upwards from the bottom of the column. This allows for convective contact between the natural water and the inert gas supplied to the column. A gas saturator is installed at the bottom of the reaction column to ensure the inert gas contains saturated water vapor (HTO). The tritized water vapor (HTO) and natural water undergo a hydrogen isotope exchange reaction, transferring tritium from the HTO to the liquid phase. A two-step reaction involving hydrogen isotope catalytic exchange and phase exchange between the HTO and natural water transfers tritium from the HTO to the liquid phase.

[0041] The catalytic washing reaction column is packed with a hydrophobic catalyst and hydrophilic filler for hydrogen isotope exchange between water and water. The hydrophobic catalyst prevents the catalytic active sites from being covered by liquid water, thus preventing catalyst "water poisoning." To achieve the hydrogen isotope exchange reaction between hydrogen and water, the hydrophobic catalyst can be a noble metal-based hydrophobic catalyst. In some embodiments, the noble metal-based hydrophobic catalyst is selected from one or more platinum (Pt)-based catalysts, which have high isotope exchange separation activity. For example, the noble metal-based hydrophobic catalyst can be selected from one or more of Pt-SDB and Pt / C-PTFE. Here, SDB represents styrene-divinylbenzene copolymer, and PTFE represents polytetrafluoroethylene. Depending on the inert gas throughput, the hydrophobic catalyst can be in particulate form or in a structured form. When the inert gas throughput is small, the corresponding natural water flow rate is also small, in which case a particulate catalyst can be selected; when the gas throughput is large, the corresponding natural water flow rate is also large, in which case a structured hydrophobic catalyst can be used to reduce the pressure drop of the catalytic washing reaction column.

[0042] The catalytic reactor is packed with a noble metal catalyst. In some embodiments, the noble metal catalyst is selected from one or more palladium (Pd) based catalysts. These catalysts enable efficient recombination reactions of hydrogen and oxygen, promoting the conversion of elemental tritium (HT) in an inert gas into water tritide (HTO). Exemplarily, the palladium (Pd) based catalyst may be selected from one or more of Pd-Al₂O₃ and Pd-MnO₂.

[0043] In some embodiments, the first packing and the second packing are each independently selected from one or more of bulk packing or structured packing. For example, the first packing and the second packing are each independently selected from one or more of stainless steel triangular spiral packing or stainless steel Dixon packing.

[0044] In the catalytic reactor, the first packing material is mixed with a noble metal catalyst and its main function is to promptly remove the heat generated by the catalytic oxidation reaction, for example, by transferring the heat to the cooling subunit located around the catalytic reactor. The first packing material can be one or more of loose packing or structured packing. Structured packing is preferred when the gas flow rate is high. Loose packing can be used when the gas flow rate is low.

[0045] Within the catalytic washing column, the second packing material is mixed with a noble metal-based hydrophobic catalyst. Its main function is to facilitate a phase exchange reaction—a liquid-phase catalytic exchange of water and hydrogen—on the surface of the second packing material. Both bulk and structured packing materials can be used. When the gas flow rate is low and the column diameter is small, a bulk catalyst and packing material can be selected to achieve better removal efficiency. When the gas flow rate is high and the column diameter is large, a structured packing material and catalyst can be selected. The second packing material is hydrophilic. This hydrophilicity provides a hydrophilic surface for phase exchange, and sufficient hydrophilicity is beneficial for the phase exchange reaction to proceed more effectively.

[0046] In some embodiments, the catalytic oxidation unit further includes a cooling subunit disposed around the catalytic reactor for dissipating the heat released by the catalytic oxidation reaction. Exemplarily, the cooling subunit may be implemented in the form of a heat exchange coil. The heat released by the catalytic oxidation reaction is dissipated through a fluid medium, such as water, within the heat exchange coil, preventing heat accumulation.

[0047] In some embodiments, the catalytic washing unit further includes a heat-insulating subunit disposed around the catalytic washing reaction column to provide a suitable constant reaction temperature for the catalytic washing reaction column. To ensure high activity of the hydrophobic catalyst, the reaction occurring in the catalytic washing unit can be carried out at 50°C to 70°C, for example, at 50°C, 60°C, or 70°C, but is not limited thereto. In this case, the catalytic washing unit may include a heat-insulating subunit disposed around the catalytic washing reaction column to provide a suitable constant reaction temperature for the catalytic washing reaction column. Exemplarily, the heat-insulating subunit may be implemented in the form of circulating heat-insulating water to maintain a constant reaction temperature. When the diameter of the catalytic washing reaction column is small, an electric heating method may also be used to provide a suitable constant reaction temperature. Here, a constant reaction temperature refers to a temperature within a specified temperature range of ±10%.

[0048] In some embodiments, the system of this application further includes a gas preheating unit ( Figure 1 (Not shown in the diagram), the gas preheating unit is disposed between the gas buffer tank and the catalytic oxidation unit, and is connected to both the gas buffer tank and the catalytic oxidation unit, for preheating the inert gas from the gas buffer tank. The preheating temperature can be 60°C to 75°C, for example, 60°C, 65°C, 70°C, or 75°C, but is not limited thereto. Exemplarily, the gas preheating unit can employ a gas heater to increase the gas temperature to a suitable reaction temperature for the catalytic oxidation reaction. When the gas flow rate is low, for example, preheating with circulating water can be used to heat the gas.

[0049] In some embodiments, the system of this application further includes a gas circulation unit 7, which is disposed between the catalytic oxidation unit 3 and the gas buffer tank 2, and connected to both the catalytic oxidation unit and the gas buffer tank, for circulating the inert gas flowing out of the catalytic oxidation unit back to the gas buffer tank. The gas circulation unit circulates the gas, allowing it to flow from the outlet of the catalytic oxidation unit into the gas buffer tank. When the concentration of elemental tritium at the outlet of the catalytic oxidation unit is high, leading to a decrease in reaction efficiency in the catalytic washing unit, the gas circulation unit allows the gas to pass through the catalytic oxidation unit multiple times for efficient conversion of elemental tritium, minimizing the tritium content at the outlet of the catalytic oxidation unit. Exemplarily, the gas circulation unit can be implemented in the form of a circulation pump, but is not limited thereto.

[0050] In some embodiments, the system of this application further includes a storage unit 6 connected to the catalytic washing unit 4 for storing tritium-containing water (HTO) flowing out of the catalytic washing unit for subsequent processing.

[0051] In some embodiments, a gas saturator is provided at the bottom of the catalytic washing reaction column to ensure that the inert gas flowing into the catalytic washing reaction column from the catalytic oxidation unit contains saturated water vapor. Exemplarily, the gas saturator can be implemented as a storage tank containing a certain amount of water.

[0052] In some embodiments, the system further includes an analysis unit. The analysis unit is connected to the catalytic oxidation unit and is used to monitor and analyze the concentration change of elemental tritium in the inert gas before and after the catalytic reaction, and can also monitor the change in oxygen concentration in the gas. Exemplarily, the analysis unit can monitor the concentration of elemental tritium and / or oxygen in the gas flowing from the gas buffer tank to the catalytic oxidation unit; and / or can monitor the concentration of elemental tritium and / or oxygen in the gas flowing out of the catalytic oxidation unit; and / or can analyze the concentration change of elemental tritium and / or oxygen in the inert gas before and after the catalytic oxidation reaction. Exemplarily, the analysis unit can be implemented in the form of an online monitoring instrument.

[0053] In some embodiments, the inert gas is a tritium-containing inert gas generated during the operation and / or decommissioning of a nuclear facility. For example, the inert gas is a tritium-containing inert gas from nuclear fuel reprocessing and / or nuclear fusion experimental devices.

[0054] A second aspect of this application provides a method for removing radioactive tritium from an inert gas, the method comprising the following steps: S1: The inert gas is filtered to remove organic components and inorganic particles. S2: Mix the inert gas filtered in step S1 with oxygen; S3: In the presence of a noble metal catalyst, the inert gas mixed with oxygen in step S2 is subjected to an oxidation reaction to convert the elemental tritium contained in the inert gas into water tritide. S4: In the presence of a noble metal-based hydrophobic catalyst, the inert gas that has undergone step S3 is brought into convective contact with natural water to transfer the radioactive tritium contained in the inert gas to the liquid water, resulting in tritium-containing water and a tritium-free inert gas; and S5: Condense the inert gas from which tritium has been removed generated in step S4.

[0055] In some embodiments, in step S4, the noble metal hydrophobic catalyst is selected from one or more platinum-based catalysts. For example, the platinum-based catalyst may be selected from one or more of Pt-SDB and Pt / C-PTFE. Here, SDB represents styrene-divinylbenzene copolymer, and PTFE represents polytetrafluoroethylene.

[0056] In some embodiments, in step S3, the noble metal catalyst is selected from one or more palladium-Pd based catalysts. For example, the palladium-Pd based catalyst may be selected from one or more of Pd-Al₂O₃ and Pd-MnO₂.

[0057] In some embodiments, the method further includes: before performing step S3, preheating the inert gas mixed with oxygen in step S2 to 60°C to 75°C, for example, to 60°C, 65°C, 70°C or 75°C, but not limited thereto.

[0058] In some embodiments, the method further includes: recycling the inert gas that has undergone step S3 to step S2 to mix with the oxygen in step S2, and then performing the oxidation reaction in step S3 again.

[0059] In some embodiments, step S3 further includes a sub-step of removing the heat generated in the oxidation reaction of step S3.

[0060] In some embodiments, the method further includes the following steps: monitoring the concentration of elemental tritium and / or oxygen in the inert gas mixed with oxygen in step S2; and / or monitoring the concentration of elemental tritium and / or oxygen in the inert gas after step S3; and / or analyzing the changes in the concentration of elemental tritium and / or oxygen in the inert gas before and after the oxidation reaction in step S3.

[0061] In some embodiments, step S4 is performed at a temperature of 50°C to 70°C. For example, step S4 is performed at 50°C, 60°C, or 70°C, but is not limited thereto.

[0062] In some embodiments, the method further includes a step of recovering the tritium-containing water generated in step S4.

[0063] In some embodiments, in step S2, the concentration of oxygen is controlled at 8% to 15% of the total volume of the gas, for example, 8%, 9%, 10%, 12%, 14%, or 15%, but not limited thereto.

[0064] In the above method, the functions and operation methods of each step are consistent with the corresponding units described in the system section of this invention. Therefore, more specific details about these steps can be found in the relevant description in the foregoing system section, and will not be repeated here.

[0065] It should be noted that the various units, modules, or components described in the system implementation of this application correspond to the various steps in the method implementation. The functions implemented by each unit, module, or component in the device correspond to the operations performed by the corresponding steps in the method. Those skilled in the art will understand that the structural features in the system implementation can be used to implement the corresponding steps in the method implementation, and conversely, the execution of each step in the method implementation can also be achieved through the operation of the corresponding units, modules, or components in the device implementation.

[0066] The present application will be described in further detail below with reference to specific embodiments. The purpose of this description is merely illustrative and not intended to limit the scope of this disclosure.

[0067] In the following embodiments, unless otherwise specified, all components used are commercially available products. Furthermore, all equipment and instruments involved are commercially available standardized products, and their operating conditions and parameter settings are in accordance with the standard instructions provided by the equipment manufacturer.

[0068] Example 1 A tritium-containing inert gas is provided, with the following composition: 98.5% helium, 0.05% HTO, 0.1% HT, and 1.35% H2O. The gas flow rate is 0.5 m³ / s. 3 / h.

[0069] The following describes the removal of tritium from the aforementioned tritium-containing inert gas: 1. The above-mentioned tritium-containing inert gas is passed through a filter including activated carbon before entering the gas buffer tank; 2. Oxygen is supplied to the gas buffer tank through the oxygen supply unit, and the oxygen concentration is controlled at 8%~15% relative to the total volume of gas; 3. The gas mixed with oxygen is preheated to approximately 70°C in a gas preheating unit before entering the catalytic oxidation unit; 4. A catalytic oxidation reaction occurs in the catalytic oxidation reactor within the catalytic oxidation unit. After the catalytic reaction, most of HT is converted to HTO, and the HT content is reduced to 1000ppm. The conversion efficiency is high. The catalytic oxidation reactor is mixed and packed with palladium-based catalyst Pd-Al2O3 and stainless steel triangular spiral packing. 5. Tritium-containing gas is supplied from the outlet of the catalytic oxidation unit to the catalytic washing reaction column. At approximately 60°C, HT undergoes a catalytic exchange reaction with water from the natural water supply unit within the catalytic washing reaction column, which is equipped with a gas saturator at the bottom, and is transferred to the liquid phase. The catalytic washing reaction column is packed with granular platinum-based hydrophobic catalyst Pt-SDB and stainless steel Dixon packing material. 6. The gas flowing out of the catalytic washing reaction column is condensed in the condensation unit. After testing, if it meets the emission requirements, it is directly discharged.

[0070] Example 2 A tritium-containing inert gas is provided, the composition of which is: 99.5% argon, 0.1% HTO, and 0.4% HT. The gas flow rate of this tritium-containing inert gas is 100 m³ / s. 3 / h.

[0071] The following describes the removal of tritium from the aforementioned tritium-containing inert gas: 1. The above-mentioned tritium-containing inert gas is passed through a filter including activated carbon before entering the gas buffer tank; 2. Oxygen is supplied to the gas buffer tank through the oxygen supply unit, and the oxygen concentration is controlled at 8%~15% relative to the total volume of gas; 3. The gas mixed with oxygen is preheated to 70°C in the gas preheating unit before entering the catalytic oxidation unit; 4. A catalytic oxidation reaction occurs in the catalytic oxidation reactor within the catalytic oxidation unit. After the catalytic reaction, most of HT is converted to HTO. The catalytic oxidation reactor is mixed and packed with palladium-based catalyst Pd-Al2O3 and stainless steel triangular Dixon packing. 5. The tritium-containing gas is returned from the outlet of the catalytic oxidation unit to the inlet of the catalytic oxidation unit via a circulation pump for recirculation. After starting the circulation pump, the recirculation lasts for approximately 1.5 hours. After recirculation, the HT content at the outlet of the catalytic oxidation unit drops to 2000 ppm; 6. Tritium-containing gas is guided from the outlet of the catalytic oxidation unit through a catalytic washing reaction column. At approximately 60°C, HT undergoes a catalytic exchange reaction with water from the natural water supply unit within the catalytic washing reaction column, which is equipped with a gas saturator at the bottom, transferring the HT to the liquid phase. The catalytic washing reaction column is packed with a structured platinum-based hydrophobic catalyst, Pt-SDB, and structured stainless steel packing. 7. The gas flowing out of the catalytic washing reaction column is condensed in the condensation unit. After testing, if it meets the emission requirements, it is directly discharged.

[0072] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A system for removing radioactive tritium from an inert gas, characterized in that, The system includes: A filtration unit is used to remove organic components and inorganic particles from the inert gas; A catalytic oxidation unit, connected to the filtration unit, is used to convert elemental tritium contained in an inert gas into tritium water. The catalytic oxidation unit is equipped with a catalytic reactor, which is filled with a noble metal catalyst and a first packing material. A gas buffer tank is disposed between and connected to the filtration unit and the catalytic oxidation unit for mixing oxygen and an inert gas from the filtration unit. An oxygen supply unit, which is connected to the gas buffer tank, is used to supply oxygen to the gas buffer tank; A catalytic washing unit, connected to the catalytic oxidation unit, is used to transfer radioactive tritium contained in the inert gas from the catalytic oxidation unit to liquid water. The catalytic washing unit is provided with a catalytic washing reaction column, wherein the catalytic washing reaction column is filled with a noble metal hydrophobic catalyst and a second packing material, the second packing material being hydrophilic, and a gas saturator is provided at the bottom of the catalytic washing reaction column to ensure that the inert gas flowing from the catalytic oxidation unit into the catalytic washing reaction column contains saturated water vapor. A natural water supply unit, connected to the catalytic washing unit, is used to supply natural water to the catalytic washing reaction column of the catalytic washing unit. The natural water is in convective contact with inert gas supplied to the catalytic washing reaction column from the catalytic oxidation unit. A condensation unit, connected to the catalytic washing unit, is used to condense the inert gas after tritium removal flowing out of the catalytic washing unit.

2. The system according to claim 1, characterized in that, The noble metal hydrophobic catalyst packed in the catalytic washing reaction column is selected from one or more platinum-based (Pt) catalysts.

3. The system according to claim 1 or 2, characterized in that, The noble metal catalyst packed in the catalytic reactor is selected from one or more palladium-Pd based catalysts.

4. The system according to any one of claims 1 to 3, characterized in that, The first packing and the second packing are each independently selected from one or more of bulk packing or structured packing.

5. The system according to any one of claims 1 to 4, characterized in that, The catalytic oxidation unit further includes a cooling subunit disposed around the catalytic reactor for dissipating the heat released by the catalytic reaction; and / or The catalytic washing unit also includes a heat-insulating subunit disposed around the catalytic washing reaction column, for providing a constant reaction temperature for the catalytic washing reaction column.

6. The system according to any one of claims 1 to 5, characterized in that, The system further includes one or more of the following units: A gas preheating unit is disposed between the gas buffer tank and the catalytic oxidation unit and is connected to the gas buffer tank and the catalytic oxidation unit, for preheating the inert gas from the gas buffer tank; A gas circulation unit is disposed between the catalytic oxidation unit and the gas buffer tank, and is connected to the catalytic oxidation unit and the gas buffer tank, for circulating the inert gas flowing out of the catalytic oxidation unit back to the gas buffer tank; or A storage unit, connected to the catalytic washing unit, is used to store tritium-containing water (HTO) flowing out from the catalytic washing unit.

7. A method for removing radioactive tritium from an inert gas, characterized in that, The method includes the following steps: S1: The inert gas is filtered to remove organic components and inorganic particles; S2: Mix the inert gas filtered in step S1 with oxygen; S3: In the presence of a noble metal catalyst, the inert gas mixed with oxygen in step S2 is subjected to an oxidation reaction to convert the elemental tritium contained in the inert gas into water tritide. S4: In the presence of a noble metal-based hydrophobic catalyst, the inert gas that has undergone step S3 is brought into convective contact with natural water to transfer the radioactive tritium contained in the inert gas to the liquid water, resulting in tritium-containing water and a tritium-free inert gas; and S5: Condense the inert gas from which tritium has been removed generated in step S4.

8. The method according to claim 7, characterized in that, In step S4, the noble metal hydrophobic catalyst is selected from one or more platinum-based (Pt) catalysts; and / or In step S3, the noble metal catalyst is selected from one or more palladium-Pd catalysts.

9. The method according to claim 7 or 8, characterized in that, The method further includes one or more of the following steps: 1) Before proceeding to step S3, the inert gas mixed with oxygen in step S2 is preheated to 60°C~75°C; 2) Recover the tritium-containing water generated in step S4.

10. The method according to any one of claims 7 to 9, characterized in that, The method further includes: recycling the inert gas that has undergone step S3 to step S2 to mix with the oxygen in step S2, and then performing the oxidation reaction in step S3 again.

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