Magnesium-nickel alloy for low-temperature efficient recovery of deuterized water and tritiated water in reactor waste gas as well as preparation method and application of magnesium-nickel alloy

Abstract

The invention belongs to the technical field of nuclear reactor waste gas treatment and radionuclide recovery, and particularly relates to a magnesium-nickel alloy for low-temperature efficient recovery of deuterized water and tritiated water in reactor waste gas and a preparation method and application of the magnesium-nickel alloy. The magnesium-nickel alloy is magnesium-nickel alloy particles, and the preparation method comprises the steps that after magnesium metal and magnesium-nickel intermediate alloy are mixed according to the design proportion, high-temperature melting is conducted, the liquid alloy is stirred till components are uniform, then pouring and natural cooling are conducted, and a magnesium-nickel alloy ingot is obtained; and then the magnesium-nickel alloy ingot is processed into magnesium-nickel alloy particles, and finally the magnesium-nickel alloy particles meeting the requirements are screened. In the magnesium-nickel alloy, the nickel element forms a micro-couple with a magnesium matrix to accelerate electrochemical corrosion and destroy the integrity mechanism of a magnesium surface oxidation film, the reaction activity of the magnesium-nickel alloy with deuterized water and tritiated water vapor is jointly improved, and deuterium and tritium isotopes in waste gas are efficiently and selectively adsorbed and fixed.

Description

Technical Field

[0001] This invention belongs to the field of nuclear reactor exhaust gas treatment and radionuclide recovery technology, specifically relating to a magnesium-nickel alloy for low-temperature and efficient recovery of deuterated water and tritated water from reactor exhaust gas, its preparation method, and its application. Background Technology

[0002] The peaceful use of nuclear energy is an important way to solve the energy crisis. During the operation of nuclear reactors, especially heavy water reactors, deuterium and tritium are key nuclear fuels or products. However, during fuel cycle, system leaks, or accident conditions, some deuterium and tritium can escape in gaseous (such as DT, T2) or vapor (deuterated water, tritized water) forms and mix into the reactor's cover gas or exhaust gas system.

[0003] Treating waste gas containing deuterated and tritium water has two major implications: First, radiation safety and environmental protection. Tritium is a radioactive beta-ray emitter. When it exists in the form of tritium water, its physicochemical properties are extremely similar to ordinary water (H2O), making it highly susceptible to participating in the natural water cycle and being absorbed by organisms, causing long-term internal radiation hazards. Therefore, it must be strictly controlled and captured. Second, resource recovery and economic efficiency. Both deuterium and tritium are extremely valuable industrial resources. Efficiently recovering these isotopes from waste gas can not only reduce fuel costs but also meet the requirements of the closed nuclear fuel cycle.

[0004] Currently, mainstream technologies for treating water vapor in reactor exhaust include condensation, distillation, and molecular sieve adsorption. However, all of these have drawbacks. For example, condensation cannot recover radioactive nuclides, distillation equipment is complex and consumes a lot of energy, and molecular sieve adsorption is sensitive to temperature and pressure and has limited adsorption capacity. In recent years, metal / alloy adsorption methods have attracted attention due to their extremely high adsorption capacity and improved high-temperature activation performance. However, when metal / alloy adsorbents are applied to the recovery of hydrogen isotopes in water vapor form, there are serious bottlenecks: First, the reactivity requirements are stringent, usually requiring high temperatures to effectively break down water molecules and adsorb hydrogen atoms, which not only brings energy consumption and safety issues but also limits its application in exhaust gases containing other sensitive components; second, the kinetics are slow, and the adsorption rate for water vapor is much lower than that for hydrogen; third, they are easily poisoned, as trace amounts of oxidizing gases in the exhaust gas can passivate their surfaces and cause rapid deactivation; finally, some materials (such as uranium) are radioactive or toxic, making their use and handling inconvenient.

[0005] In metal / alloy getter methods, magnesium and its alloys have been widely studied in the field of hydrogen storage due to their advantages such as high hydrogen storage capacity, abundant resources, light weight, and non-radioactivity, and have the potential for application in hydrogen isotope separation and recovery. However, traditional magnesium-based hydrogen storage materials usually require relatively high temperatures to achieve considerable hydrogen adsorption / desorption kinetics, mainly due to the stability of MgH2 and the energy barrier for hydrogen atom diffusion in the magnesium lattice. Therefore, if existing magnesium-based materials are used directly, effective adsorption is almost impossible in low-temperature, water-vapor-containing deuterium / tritium recovery environments.

[0006] This invention provides a novel magnesium-based material capable of efficiently, rapidly, and selectively adsorbing deuterium and tritium isotopes in water vapor form at relatively low temperatures in a safe and energy-efficient manner. This is of great significance for the development of nuclear energy technology, the minimization of radioactive waste, and resource recycling. Summary of the Invention

[0007] To address the aforementioned technical problems, one objective of this invention is to provide the application of magnesium-nickel alloy as an alloy adsorbent for the low-temperature and efficient recovery of deuterated and tritized water from reactor exhaust gas.

[0008] Preferably, in the magnesium-nickel alloy, nickel accounts for 15-30% by mass percentage, with the remainder being magnesium and unavoidable impurities, the total mass of which does not exceed 0.5% of the total mass of the magnesium-nickel alloy.

[0009] The aforementioned unavoidable impurities may include one or more metallic impurities such as iron, copper, silicon, and cobalt, as well as non-metallic inclusions; the non-metallic inclusions may be magnesium oxide, magnesium nitride, and a small amount of chloride.

[0010] Preferably, the magnesium-nickel alloy is in the form of particles with a particle size of 0.5 to 1 mm, and the magnesium-nickel alloy is filled into the reaction bed in the form of particles for adsorption, with a filling density of 50 to 70%.

[0011] A second objective of this invention is to provide an alloy adsorbent for the low-temperature, high-efficiency recovery of deuterated and tritated water from reactor exhaust gas. The alloy adsorbent is a magnesium-nickel alloy with a particle size of 0.5–1 mm and a specific surface area of ​​0.01–0.1 m². 2 / g of magnesium-nickel alloy particles.

[0012] Preferably, in the magnesium-nickel alloy, nickel accounts for 15-30%, and the remainder is magnesium and unavoidable impurities, the total mass of which does not exceed 0.5% of the total mass of the magnesium-nickel alloy.

[0013] The third objective of this invention is to provide a method for preparing the alloy adsorbent described above for the low-temperature and efficient recovery of deuterated and tritated water from reactor exhaust gas, comprising the following steps: S1. According to the required ratio of magnesium and nickel in the alloy adsorbent, obtain an appropriate amount of metallic magnesium and magnesium-nickel intermediate alloy, mix them, melt them at high temperature and stir the liquid alloy until the composition is uniform, then cast and cool naturally to obtain magnesium-nickel alloy ingots. S2. Process the magnesium-nickel alloy ingot into magnesium-nickel alloy particles; S3. Screen magnesium-nickel alloy particles that meet the requirements for particle size and specific surface area, which are the desired alloy adsorbents.

[0014] Preferably, the mass percentage of nickel in the magnesium-nickel master alloy is 20% to 50%.

[0015] The above preparation method uses a magnesium-nickel master alloy instead of pure nickel as the nickel source, mainly based on the following technical considerations: First, it reduces smelting temperature and energy consumption. Pure nickel has a melting point as high as 1455℃, while the eutectic temperature of Mg-Ni binary alloys is 506℃. When using magnesium-nickel master alloys (such as Mg-30Ni), its initial melting temperature is the eutectic temperature (approximately 506℃). A semi-solid or liquid melt with good fluidity can be formed within a lower temperature range, significantly lower than the smelting temperature of pure nickel. This is beneficial for saving energy, shortening the process cycle, and reducing magnesium oxidation loss.

[0016] Second, it inhibits the precipitation and segregation of nickel. The density of nickel (8.90 g / cm³) 3 The concentration of magnesium (1.74 g / cm³) is much higher than that of magnesium. 3 If pure nickel is added directly to the magnesium melt, the nickel particles will easily sink to the bottom due to gravity, resulting in severe inhomogeneity of the alloy composition. When using a magnesium-nickel master alloy, the nickel has already formed an alloy or intermetallic compound with the magnesium, and its apparent density is close to that of the magnesium melt. This significantly improves the suspension and dispersion uniformity of nickel in the melt, thereby obtaining an alloy ingot with a more uniform microstructure and a more dispersed second phase distribution.

[0017] In this preparation method, the magnesium-nickel master alloy used can be prepared by oneself or a finished product that meets the requirements can be purchased. This invention does not impose any special restrictions on this.

[0018] Preferably, the high-temperature melting conditions are as follows: heating to 650-800°C at a heating rate of 5-15°C / min, and holding at that temperature until melting.

[0019] The fourth objective of the invention is to provide a reactor exhaust gas treatment system, including a reaction bed filled with the alloy adsorbent described above, with a filling density of 50-70%.

[0020] Preferably, the working temperature of the alloy adsorbent is 375~425℃, and the total concentration of deuterated water and tritized water vapor in the adsorbed reactor exhaust gas is 100~6000 ppm.

[0021] Preferably, the reactor exhaust gas is an inert carrier gas, and the flow rate of the reactor exhaust gas through the reactor bed is less than 1 L / min.

[0022] The beneficial effects of this invention are as follows: Magnesium alloys are widely used hydrogen storage materials. Currently, mainstream technologies for reactor tritium recovery are unrelated to magnesium alloys. Patent CN114898908A discloses a method for treating tritium-containing waste gas based on magnesium-based metals, but it only targets dry tritium-containing waste gas and does not specify the exact composition of the magnesium alloy powder. Due to certain defects of alloy materials in water-vapor environments, alloys, including magnesium-based alloys, are generally not used in the field to recover deuterated and tritized water from reactor waste gas. This application provides a simple and effective method, breaking through this application bottleneck.

[0023] This application utilizes magnesium as a matrix and achieves efficient recovery of deuterated water (D2O) and tritized water (T2O) at low temperatures by adding a specific amount of nickel (Ni). The addition of nickel alters the microstructure of the magnesium alloy, specifically by forming intermetallic compounds (such as the Mg2Ni phase) within the magnesium matrix. This phase precipitates densely at grain boundaries, forming a second-phase strengthening structure. This microstructure evolution significantly enhances the alloy's reactivity with water vapor primarily through the following synergistic mechanism: 1) There is a significant difference in electrochemical inertia between the second phase (such as Mg2Ni) and the magnesium matrix, which form a high-density micro-electrical couple within the alloy. The second phase acts as the cathode and the magnesium matrix as the anode, thereby initiating and accelerating the electrochemical corrosion process in a localized area, providing more active sites for the reaction between water molecules and magnesium.

[0024] 2) The precipitation of the second phase at the grain boundaries and its physical properties differ from those of the matrix disrupt the integrity of the originally continuous and dense magnesium oxide (MgO) protective film on the surface of pure magnesium, leading to defects such as microcracks or pores in the oxide film. This incomplete surface film facilitates the direct penetration of water vapor molecules to the fresh surface of the magnesium matrix, significantly reducing the activation energy barrier of the reaction, allowing the alloy to initiate and maintain a highly efficient reaction at a lower temperature.

[0025] Therefore, the magnesium-nickel alloy provided by this invention, by changing the thermodynamic state of the system, lowers the temperature threshold required for recycling, and enhances the reactivity and adsorption kinetics of the magnesium-nickel alloy with deuterated water and tritized water vapor at lower temperatures. It can efficiently and selectively adsorb and fix deuterium and tritium isotopes in waste gas at operating temperatures significantly lower than those of traditional metal getters, effectively reducing the risk of tritium radiation emissions, while also taking into account the recycling of valuable nuclide resources, thus achieving both environmental safety and economic benefits.

[0026] Specifically: 1) Significantly reduced operating temperature, optimized energy consumption and safety: The magnesium-nickel alloy provided in this application can work efficiently at 375~425℃. The effective adsorption starting temperature is more than 50℃ lower than that of pure magnesium, and is also far lower than the high temperature required by traditional metal getters, thus avoiding high energy consumption and significantly reducing system operating costs and safety risks.

[0027] 2) Efficient recovery of deuterium and tritium resources: This magnesium-nickel alloy has high reactivity towards deuterated water and tritized water vapor, and can capture and fix these isotopes from complex waste gases, converting deuterated or tritized water in the waste gas into deuterium or tritium gas. Subsequently, deuterium and tritium gas in the waste gas can be efficiently separated and recovered through mature and large-scale industrial methods such as pressure swing adsorption and membrane separation, directly achieving resource enrichment, with significant economic benefits, while completely eliminating the hidden danger of radioactive emissions.

[0028] 3) Excellent material adsorption performance and long service life: By changing the adsorption kinetics of the system through the action mechanism of nickel, the adsorption speed and high reactivity are achieved; the specific composition and structural design of the alloy ensures the stability and service life of the material during long-term service.

[0029] 4) The preparation process is simple and easy to engineer: The alloy of this invention adopts conventional smelting and processing technology, the preparation method is simple and the cost is controllable, and the resulting particulate material is easy to integrate into existing or newly built waste gas treatment devices, providing a reliable and efficient passive safety treatment solution for nuclear facilities. Attached Figure Description

[0030] Figure 1 The image shows the microstructure of the magnesium-nickel alloy particles prepared in Example 1.

[0031] Figure 2 The X-ray diffraction pattern of the magnesium-nickel alloy particles prepared in Example 1.

[0032] Figure 3 Differential scanning calorimetry curves of the magnesium-nickel alloy particles prepared in Example 1.

[0033] Figure 4 The results show the water absorption properties of the magnesium-nickel alloy particles and metallic magnesium prepared in Example 1.

[0034] Figure 5 The corrosion electrochemical properties of the magnesium-nickel alloy particles and metallic magnesium prepared in Example 1 are shown.

[0035] Figure 6 The results show the long-term stability of the water absorption properties of the magnesium-nickel alloy particles prepared in Example 1.

[0036] Figure 7 The X-ray diffraction pattern of the reaction products of the magnesium-nickel alloy particles prepared in Example 1.

[0037] Figure 8 X-ray photoelectron spectroscopy of the reaction products of the magnesium-nickel alloy particles prepared in Example 1.

[0038] Figure 9 The results show the water absorption properties of the magnesium-nickel alloy particles prepared in Example 2.

[0039] Figure 10 The results are from the water absorption test of the magnesium-nickel alloy particles prepared in Example 3. Detailed Implementation

[0040] Unless otherwise stated, the terms used herein have the meanings commonly understood by those skilled in the art.

[0041] The technical solution of the present invention will be described in more detail below with reference to the embodiments.

[0042] Example 1 A magnesium-nickel alloy with a nickel mass percentage of 24% is disclosed for the low-temperature, high-efficiency recovery of deuterated and tritated water from reactor exhaust gas. Appropriate amounts of metallic magnesium and a magnesium-nickel master alloy (Ni 40wt%) are mixed according to the required proportions and placed in a vacuum induction melting furnace. The temperature is increased to 750℃ at a rate of 10℃ / min until completely melted, and then held at this temperature with thorough stirring to ensure uniform composition. The molten alloy is then cast into ingots and allowed to cool naturally to room temperature to obtain magnesium-nickel alloy ingots. These ingots are then mechanically crushed to obtain magnesium-nickel alloy particles. Finally, the particles are sieved to obtain a particle size of approximately 0.7 mm and a specific surface area of ​​approximately 0.06 m². 2 / g of magnesium-nickel alloy particles are used as alloy adsorbents.

[0043] The prepared magnesium-nickel alloy particles were characterized, and the results are shown in [reference needed]. Figures 1-3 .

[0044] Figure 1 The microstructure of the prepared magnesium-nickel alloy particles shows that they are irregularly shaped with an equivalent sphere radius of approximately 0.7 mm. The particles have a rough surface and uniform size distribution, which is beneficial for providing a large specific surface area. Calculations show that the specific surface area is approximately 0.06 m². 2 / g.

[0045] Figure 2 The X-ray diffraction pattern of the prepared magnesium-nickel alloy particles is shown. Analysis indicates that the magnesium-nickel alloy is mainly composed of the α-Mg phase and the intermetallic compound Mg2Ni phase, with no separate Ni phase peaks observed, indicating that Ni has formed a compound or solid solution with Mg.

[0046] Figure 3Differential scanning calorimetry (DSC) curves of the prepared magnesium-nickel alloy particles are shown. During the heating process, a distinct endothermic peak was observed at approximately 509 °C. Referring to the Mg-Ni binary phase diagram, this temperature closely matches the Mg-Mg₂Ni eutectic transformation temperature (505 °C), and this endothermic peak corresponds to the melting process of the eutectic structure in the alloy.

[0047] Adsorption experiment

[0048] An alloy adsorbent was filled into a reaction bed at a density of 60% to adsorb and recover water vapor at a concentration of 6000 ppm from waste gas. The waste gas was an inert carrier gas with an oxygen content not exceeding 100 ppm. The water vapor concentration at the reactor outlet was monitored using a high-precision dew point meter. Simultaneously, pure magnesium was used as a comparative example (Example 1) to test its water absorption performance under the same conditions.

[0049] It should be emphasized that this adsorption experiment aims to verify the adsorption capacity of the magnesium-nickel alloy of the present invention for water vapor. Although ordinary water is used as the adsorbate, the results can be directly extrapolated to deuterated water and tritized water vapor because: (1) The essence of the reaction is oxygen-metal bonding, which is unrelated to the type of hydrogen isotope. The core of the reaction between magnesium alloy and water vapor is that magnesium combines with oxygen to form MgO, and hydrogen (or deuterium, tritium) is released in molecular or atomic form. The chemical properties of hydrogen and its isotopes are exactly the same, and the reaction mechanism is consistent.

[0050] (2) Isotope tracing studies have directly confirmed the consistency of behavior. Literature reports (Brady et al., 2015, 2017; Splinter et al., 1994) used deuterated water and ordinary water for sequential exposure experiments, and proved by secondary ion mass spectrometry analysis that there is no essential difference in the adsorption kinetics of H2O and D2O, oxygen film formation behavior and hydrogen (deuterium) permeation behavior of magnesium alloys.

[0051] (3) The isotope effect is negligible at the service temperature (375~425℃) of this invention. The difference in zero-point energy between OH bonds and OD bonds is much smaller than the thermal kinetic energy at high temperatures, and its effect on the reaction rate is negligible.

[0052] The adsorption performance data obtained in this experiment using ordinary water vapor can quantitatively reflect the adsorption capacity of the magnesium-nickel alloy for deuterated water and tritized water vapor.

[0053] See results Figures 4-7 .

[0054] Figure 4The experimental graphs show the water absorption performance of magnesium-nickel alloy particles and metallic magnesium, illustrating the change in outlet water vapor concentration over time at two different carrier gas flow rates (0.5 L / min and 1 L / min). The results indicate that at both flow rates, the outlet water vapor concentration of the magnesium-nickel alloy particle test group rapidly decreased from an initial 6000 ppm to 0 ppm (below the detection limit) and remained stable over a long period, demonstrating the excellent and rapid adsorption capacity of magnesium-nickel alloy for water vapor at 375℃. However, at 350℃, the water vapor concentration of the metallic magnesium test group was significantly higher than that of the magnesium-nickel alloy particle test group, and its adsorption of the initial water vapor concentration of 6000 ppm was weak (at which point the magnesium-nickel alloy particle test group already exhibited excellent adsorption performance). Only when the temperature of the metallic magnesium test group was increased to approximately 425℃ did its outlet water vapor concentration decrease from the initial 6000 ppm to 0 ppm and remain stable. This demonstrates that the effective operating temperature of the magnesium-nickel alloy in this invention is reduced by approximately 50℃, directly proving the crucial role of Ni element in improving the low-temperature water removal performance of magnesium-based materials.

[0055] Figure 5 The results show the comparison of corrosion performance between magnesium-nickel alloy particles and metallic magnesium. It can be seen that the addition of Ni element reduces the corrosion potential and increases the corrosion current density of the alloy, which means that its corrosion tendency and rate are higher than those of pure magnesium. This provides key evidence to explain its improved reactivity: (1) Microgalvanic corrosion effect: There is a potential difference between Ni (or Ni-rich Mg2Ni phase) and Mg matrix, forming a micro galvanic cell inside the alloy, which accelerates the anodic dissolution process of Mg; (2) Oxide film modification: The addition of Ni destroys the continuous and dense MgO protective film formed on the surface of pure magnesium, making it porous or prone to cracking. This incomplete oxide film is conducive to the direct penetration of water vapor molecules to the fresh Mg matrix surface, reducing the reaction activation energy. The above mechanisms work together to achieve a significant improvement in the reactivity of magnesium-nickel alloy and a significant reduction in the operating temperature.

[0056] Figure 6 This study investigated the long-term stability of the water absorption properties of the prepared magnesium-nickel alloy particles. As can be seen, under a constant temperature of 375℃, the outlet water vapor concentration remained stable at around 0 ppm throughout the entire test period. This result fully demonstrates that the magnesium-nickel alloy of this invention not only has high initial activity but also excellent long-term operational stability, meeting the requirements for material lifespan.

[0057] Figure 7 The image shows the X-ray diffraction pattern of the reaction product from Example 1. It can be seen that, in addition to the residual Mg and Mg₂Ni phases, a distinct MgO diffraction peak appears. This directly confirms that Mg in the alloy underwent an oxidation reaction with water vapor (Mg + H₂O → MgO + H₂), while the Mg₂Ni phase did not undergo a phase transformation during this process.

[0058] Figure 8 The X-ray photoelectron spectroscopy (XPS) spectrum of the reaction product from Example 1 shows two peaks at binding energies of 1303.0 eV and 1303.9 eV, corresponding to metallic Mg and oxidized Mg (MgO), respectively. Surface analysis using XPS further confirms the formation of MgO and indicates that the chemical state of Ni did not change significantly, supporting the conclusion that Ni primarily plays a catalytic and structural adjustment role.

[0059] In addition, a magnesium-nickel alloy containing 5% nickel by mass was set as Comparative Example 2, with the rest of the experiment the same as in Example 1. The results showed that the outlet water vapor concentration only decreased from the initial 6000 ppm to 0 ppm and remained stable when the temperature rose to about 425°C.

[0060] Using an aluminum alloy as Comparative Example 3, and a magnesium-aluminum alloy with an aluminum mass percentage of 24% and the same as in Example 1, experiments were conducted. The results showed that the outlet water vapor concentration only decreased from the initial 6000 ppm to 0 ppm and remained stable when the temperature rose to approximately 450°C.

[0061] As can be seen, the magnesium-aluminum alloy provided in the embodiments has the lowest service temperature.

[0062] Example 2 The difference between Example 2 and Example 1 is that the mass percentage of nickel in the magnesium-nickel alloy is 15%.

[0063] The water absorption properties of the prepared magnesium-nickel alloy particles are described in [reference needed]. Figure 9 The results showed that the magnesium-nickel alloy exhibited excellent water absorption performance under constant temperature conditions of 375℃, and the outlet water vapor concentration could be rapidly reduced from the initial 6000 ppm to 0 ppm.

[0064] Example 3 The difference between Example 3 and Example 1 is that the mass percentage of nickel in the magnesium-nickel alloy is 30%.

[0065] The water absorption properties of the prepared magnesium-nickel alloy particles are described in [reference needed]. Figure 9 The results showed that the magnesium-nickel alloy exhibited excellent water absorption performance under constant temperature conditions of 375℃, and the outlet water vapor concentration could be rapidly reduced from the initial 6000 ppm to 0 ppm.

[0066] The above examples and comparative examples illustrate the following: This invention prepares a magnesium-nickel alloy for the low-temperature, high-efficiency recovery of deuterated and tritated water from reactor exhaust gases by adding a specific amount (15-30 wt%) of nickel to a magnesium matrix. This alloy exhibits significantly higher adsorption reactivity for water vapor than pure magnesium, and its effective operating temperature can be reduced by approximately 50°C, achieving the goal of "low-temperature, high-efficiency." The alloy also possesses excellent long-term operational stability and has clear engineering application value.

[0067] The magnesium-nickel alloy provided by this invention offers a novel solution for the efficient low-temperature recovery of deuterium and tritium isotopes from reactor exhaust gas.

[0068] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. Application of magnesium-nickel alloy as an alloy adsorbent for low-temperature and efficient recovery of deuterated and tritized water from reactor exhaust gas.

2. The application as described in claim 1, characterized in that, In the magnesium-nickel alloy, nickel accounts for 15-30% by mass, with the remainder being magnesium and unavoidable impurities, the total mass of which does not exceed 0.5% of the total mass of the magnesium-nickel alloy.

3. The application as described in claim 1, characterized in that, The magnesium-nickel alloy consists of particles with a diameter of 0.5 to 1 mm. The magnesium-nickel alloy is filled into the reaction bed in particle form for adsorption, with a filling density of 50 to 70%.

4. An alloy adsorbent for low-temperature and high-efficiency recovery of deuterated water and tritated water from reactor exhaust gas, characterized in that, It is a magnesium-nickel alloy, wherein the magnesium-nickel alloy has a particle size of 0.5~1 mm and a specific surface area of ​​0.01~0.1 m². 2 / g of magnesium-nickel alloy particles.

5. The alloy adsorbent as described in claim 4, characterized in that, In the magnesium-nickel alloy, nickel accounts for 15-30%, and the remainder is magnesium and unavoidable impurities. The total mass of the unavoidable impurities does not exceed 0.5% of the total mass of the magnesium-nickel alloy.

6. A method for preparing an alloy adsorbent for low-temperature and high-efficiency recovery of deuterated and tritated water from reactor exhaust gas, as described in claim 4 or 5, characterized in that... Includes the following steps: S1. According to the required ratio of magnesium and nickel in the alloy adsorbent, obtain an appropriate amount of metallic magnesium and magnesium-nickel intermediate alloy, mix them, melt them at high temperature and stir the liquid alloy until the composition is uniform, then cast and cool naturally to obtain magnesium-nickel alloy ingots. S2. Process the magnesium-nickel alloy ingot into magnesium-nickel alloy particles; S3. Screen magnesium-nickel alloy particles that meet the requirements for particle size and specific surface area, which are the desired alloy adsorbents.

7. The preparation method according to claim 6, characterized in that, In the magnesium-nickel master alloy, the mass percentage of nickel is 20% to 50%.

8. The preparation method according to claim 6, characterized in that, The high-temperature melting conditions are as follows: the temperature is increased to 650-800°C at a heating rate of 5-15°C / min, and held at that temperature until melting.

9. A reactor exhaust gas treatment system, characterized in that, It includes a reaction bed filled with the alloy adsorbent as described in claim 4 or 5, with a filling density of 50-70%.

10. A reactor exhaust gas treatment system as described in claim 9, characterized in that, The alloy adsorbent operates at a temperature of 375~425℃, and the total concentration of deuterated water and tritized water vapor in the adsorbed reactor exhaust gas is 100~6000 ppm.

11. A reactor exhaust gas treatment system as described in claim 10, characterized in that, The reactor exhaust gas is an inert carrier gas, and the flow rate of the reactor exhaust gas through the reactor bed is less than 1 L / min.

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