A radioactive alpha chemical deposition mud simulation system and its preparation method

Abstract

The application discloses a radioactive alpha chemical deposition slurry simulation system and a preparation method thereof, and belongs to the technical field of radioactive waste treatment. The preparation method comprises the following steps: calculating the amount of the simulation slurry reagent according to the element analysis result of the medium radioactive alpha chemical deposition slurry; simulating a chemical deposition slurry formation process, and preparing a simulation slurry mother liquor according to preset steps; and performing evaporation concentration treatment and drying treatment on the simulation slurry mother liquor, and then adding water according to the actual slurry water content to prepare the radioactive alpha deposition slurry simulation system. The method can accurately simulate the chemical composition and water content of the actual slurry and other indexes, meets the demand of the slurry chemical characteristics of the treatment route exploration experiment, and fundamentally eliminates the irradiation exposure risk of experimenters in the sample preparation, process operation and data acquisition and other links.

Description

Technical Field

[0001] This application relates to the field of radioactive waste treatment technology, and more specifically, to a radioactive alpha chemical deposition mud simulation system and its preparation method. Background Technology

[0002] In the reprocessing of the uranium-plutonium fuel cycle, a large amount of intermediate-level radioactive waste is inevitably generated. Due to the mixed loading of sodium aluminate waste, organic waste, acidic waste, and residual liquid from desorption waste during the receiving and storage process in old tank areas, the salt in the waste reacts and precipitates at the bottom of the intermediate-level radioactive waste storage tank, forming a chemically deposited slurry layer. This type of radioactive waste is characterized by high salt content, complex composition, and high content of transuranic nuclides (as well as α waste such as Pu and Am), and the total radioactivity of this waste reaches an intermediate level.

[0003] Currently, there are no clear standards or methods for the disposal of intermediate-level radioactive waste. To achieve the safe treatment and disposal of this type of radioactive waste as soon as possible, it is necessary to conduct extensive exploratory experiments on various treatment technologies, including cement solidification, vitrification, acid leaching and degradation, microwave calcination, and microwave drying. Among these, microwave calcination technology, with its core technology, has significant advantages in treating intermediate-level radioactive alpha chemical deposition mud, including removing free water to prevent hydrogen explosions, significantly reducing volume to lower transportation and storage costs, and converting unstable chemical forms into stable metal oxide forms to ensure long-term storage safety. It is one of the important technological directions for the disposal of this type of mud.

[0004] However, there is currently a lack of research foundation and engineering practice in this field, and its feasibility needs to be verified through experiments. Before conducting engineering calcination experiments, it is necessary to prepare simulated mud to simulate actual radioactive alpha chemical deposition mud. Existing mud simulation system preparation methods are difficult to accurately simulate the chemical composition and characteristics of radioactive alpha chemical deposition mud, and cannot provide a reliable basis for subsequent experiments. Therefore, a new simulation system preparation method is urgently needed. Summary of the Invention

[0005] The purpose of this application is to provide a simulation system for radioactive alpha chemical deposition mud and its preparation method, which can obtain a simulation system with chemical composition, water content and other indicators similar to actual radioactive alpha chemical deposition mud. This provides a reliable simulation object for engineering calcination experiments in the research of microwave calcination technology for radioactive alpha chemical deposition mud, and further helps to verify the feasibility of microwave calcination technology for treating radioactive alpha chemical deposition mud.

[0006] To achieve the above objectives, this application provides a method for preparing a radioactive alpha chemical deposition mud simulation system, comprising the following steps:

[0007] Based on the elemental analysis results of the moderately radioactive alpha chemical deposition mud, the proportion of raw materials used to prepare the simulated mud was calculated.

[0008] Based on the aforementioned raw material ratio, a first solution is prepared using ferric nitrate nonahydrate, neodymium nitrate hexahydrate, and water as raw materials. The first solution is then gradually prepared into a simulated mud mother liquor according to a preset procedure.

[0009] The simulated mud mother liquor was subjected to evaporation and concentration treatment and drying treatment in sequence to obtain simulated dry mud.

[0010] Based on the water content of the moderately radioactive alpha chemical deposition mud, water was added to the simulated dry mud to prepare a simulated system of radioactive alpha chemical deposition mud; wherein...

[0011] The preset steps include: based on the raw material usage ratio, converting the first solution into the simulated mud mother liquor according to the conversion path of the first solution, the second solution, the third solution, the primary mother liquor, and the simulated mud mother liquor.

[0012] Furthermore, the ratio of ferric nitrate nonahydrate, neodymium nitrate hexahydrate, and water in the first solution is 1 kg : (2 kg ~ 4 kg) : (10 L ~ 30 L).

[0013] Furthermore, the method for converting the first solution into the second solution includes: based on the raw material dosage ratio, mixing phosphoric acid, ferrous sulfate and water evenly, and then sequentially adding tricalcium phosphate and the first solution to obtain the second solution; wherein the ratio of phosphoric acid, ferrous sulfate, tricalcium phosphate and water is (30kg~50kg):1kg:(1kg~4kg):(600L~1200L).

[0014] Furthermore, the method for converting the second solution into the third solution includes: based on the raw material dosage ratio, mixing manganese dihydrogen phosphate dihydrate, boron anhydride and water evenly, and then adding the second solution to obtain the third solution; wherein the ratio of manganese dihydrogen phosphate dihydrate, boron anhydride and water is (2kg~8kg):(1kg~5kg):(800L~1200L).

[0015] Furthermore, the method for converting the third solution into a primary mother liquor includes: mixing the sodium metasilicate nonahydrate aqueous solution with the third solution based on the raw material dosage ratio, and obtaining the primary mother liquor after the precipitation of white flocculent matter; wherein, the ratio of sodium metasilicate nonahydrate to water in the sodium metasilicate nonahydrate aqueous solution is (3kg~4kg):(80L~120L).

[0016] Furthermore, the method for converting the primary mother liquor into simulated mud mother liquor includes: mixing an aqueous solution of sodium aluminate with the primary mother liquor based on the raw material dosage ratio, and obtaining the simulated mud mother liquor after the precipitation of agglomerated flocs; wherein,

[0017] The ratio of sodium aluminate to water in the sodium aluminate aqueous solution is 1 kg: (10 L~15 L).

[0018] Furthermore, the evaporation and concentration process is carried out at a temperature of 100℃~110℃ for 1h~2h.

[0019] Furthermore, the drying process is carried out at a temperature of 60℃ to 90℃ for a duration of more than 8 hours.

[0020] Furthermore, in the preparation process of the radioactive α-chemical deposition mud simulation system, the ratio of the simulated dry mud to water is 1 kg: (1 L~4 L).

[0021] This application also provides a radioactive alpha chemical deposition mud simulation system obtained according to a preparation method.

[0022] In summary, this application has the following advantages:

[0023] (1) This application simulates the formation process of radioactive α chemical sediment mud by using non-radioactive chemical reagents and radioactive nuclides as substitutes to synthesize a non-radioactive simulated mud system with similar chemical composition and physical properties. This reduces the impact of irradiation on the experimenters during the radioactive α chemical sediment mud treatment route experiment and improves the safety of the experiment.

[0024] (2) This application synthesized a large amount of simulated mud by simulating the formation process of radioactive α chemical deposition mud, which solved the transportation problem of radioactive α chemical deposition mud for engineering verification experiments in other locations, as well as the problem of sending out products of various processing routes for testing.

[0025] (3) The radioactive α chemical deposition mud simulation system prepared by the method of this application is similar to the actual mud in terms of physical properties. It can effectively simulate the physical behavior of mud in pipeline transportation and treatment process, and provide important basis for equipment design and process parameter optimization in nuclear facility decommissioning and radioactive waste treatment projects, thereby reducing the risks and costs in actual engineering operations. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 These are images of intermediate materials used in the preparation process of the radioactive α-chemical deposition mud simulation system involved in Example 1 of this application; wherein, Figure 1 Image (a) in the image is a simulated mud mother liquor. Figure 1 Image (b) shows a simulated image of mud after evaporation and concentration. Figure 1 (c) in the image is a simulated image of dry mud after grinding.

[0028] Figure 2 This is a schematic flowchart illustrating the preparation method of the radioactive α-chemical deposition mud simulation system involved in the embodiments of this application. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] In nuclear energy utilization systems, the reprocessing technology of the uranium-plutonium fuel cycle is a crucial link in achieving nuclear fuel resource recovery and safe management. However, this process inevitably generates a large amount of intermediate-level radioactive waste liquid during operation. In the actual operation of aging waste liquid storage areas, due to historical operating conditions and storage planning limitations, there are instances of mixed storage of various types of waste liquid, including sodium aluminate waste liquid, organic waste liquid, acidic waste liquid, and desorption waste liquid residue. This mixed storage leads to complex chemical reactions of various salts in the waste liquid at the bottom of the intermediate-level radioactive waste liquid storage tanks, which gradually precipitate out and ultimately form a chemically deposited slurry layer with specific physicochemical properties. This type of intermediate-level radiochemical sedimentary mud has significant unique characteristics: First, it has an extremely high salt content, with the proportion of soluble salts in the system far exceeding that of conventional industrial waste. Second, it has a complex chemical composition, containing not only a large number of metal ions but also various compounds such as organic residues, phosphates, and silicates. Third, it poses a prominent radioactive risk, not only reaching the standard for intermediate-level radioactive waste in terms of total radioactivity level but also being rich in transuranic nuclides such as Pu and Am. These nuclides have long half-lives and high alpha radiation toxicity, posing stringent requirements for the safety of the disposal process.

[0031] Currently, there is no perfect method for treating this type of moderately radioactive chemically deposited mud. Various methods are being explored, including cement solidification, vitrification, acid leaching and degradation, microwave drying, and microwave calcination. Among these, microwave calcination technology is considered a highly promising and important technological direction due to its unique advantages: This technology can efficiently remove free water and crystal water from the mud through microwave heating, avoiding the risk of hydrogen explosions caused by the interaction of water and radioactive materials during subsequent treatment and storage; simultaneously, microwave calcination can significantly reduce the volume of the mud, significantly lowering the costs of subsequent transportation, temporary storage, and final disposal; furthermore, the calcination process can convert unstable chemical forms in the mud (such as easily soluble salts and hydroxides) into stable solid forms such as metal oxides, effectively improving the long-term storage safety of the waste and reducing the risk of radionuclide migration and diffusion. However, although microwave calcination technology has shown promising application prospects, it is still in its early stages, lacking both a systematic theoretical research foundation and relevant engineering practical experience for reference. Its technical feasibility and engineering applicability need to be confirmed through extensive experimental verification. Before conducting microwave calcination engineering experiments, a crucial prerequisite is the preparation of a simulated slurry capable of accurately mimicking actual intermediate-level radioactive alpha chemical deposition slurry. Only a simulated system highly consistent with the actual slurry's chemical composition, physical properties (such as water content, density, and fluidity), and radioactivity (such as the distribution and morphology of substituted nuclides) can provide valuable reference data for process parameters and treatment effects, offering reliable support for subsequent engineering applications. However, existing slurry simulation systems generally have limitations, failing to accurately replicate the complex chemical composition and key characteristics of actual intermediate-level radioactive alpha chemical deposition slurry. This results in significant deviations between the simulated system and actual waste, hindering the experimental research of treatment technologies such as microwave calcination and thus restricting the development of such treatment technologies. Therefore, this application provides a radioactive alpha chemical deposition slurry simulation system and its preparation method.

[0032] In a first aspect, this application provides a method for preparing a radioactive alpha chemical deposition mud simulation system, comprising the following steps:

[0033] S1. Based on the elemental analysis results of the moderately radioactive α-chemical deposition mud, calculate the proportion of raw materials used to prepare the simulated mud.

[0034] S2. Based on the raw material ratio, a first solution is prepared using ferric nitrate nonahydrate, neodymium nitrate hexahydrate, and water as raw materials. The first solution is then gradually prepared into a simulated mud mother liquor according to preset steps.

[0035] S3. The simulated mud mother liquor is subjected to evaporation and concentration treatment and drying treatment in sequence to obtain simulated dry mud.

[0036] S4. Based on the water content of the medium-level radioactive alpha chemical deposition mud, water is added to the simulated dry mud to prepare a simulated system of radioactive alpha chemical deposition mud.

[0037] In a specific implementation, the preset steps include: based on the raw material usage ratio, converting the first solution into the simulated mud mother liquor according to the conversion path of the first solution, the second solution, the third solution, the primary mother liquor, and the simulated mud mother liquor.

[0038] In a specific implementation, the ratio of ferric nitrate nonahydrate, neodymium nitrate hexahydrate, and water in the first solution is 1 kg : (2 kg~4 kg) : (10 L~30 L). To simulate the chemical behavior of α-nuclides such as U, Pu, and Am in actual mud, this application selects neodymium (Nd) as a substitute for uranium (U): Nd is highly similar to uranium in chemical properties such as ionic radius, valence (both readily form +3 valent ions), and coordination ability with anions (such as nitrate and phosphate), accurately simulating the dissolution, precipitation, and coordination reaction behavior of uranium during mud formation; simultaneously, Nd is non-radioactive, fundamentally eliminating the radiation risk associated with actual nuclides. This approach retains the chemical simulation of nuclides while resolving experimental safety and transportation compliance issues.

[0039] In a specific embodiment, the method for converting the first solution into the second solution includes: based on the raw material ratio, mixing 30kg~50kg of phosphoric acid, 1kg of ferrous sulfate, and 600L~1200L of water evenly, then sequentially adding 1kg~4kg of tricalcium phosphate and the first solution to obtain the second solution. This application addresses the actual characteristics of moderately radioactive α-chemical deposition mud rich in phosphate components such as iron phosphate and calcium phosphate. It precisely matches the binding process of phosphates and metal ions in actual mud by first constructing a phosphate-ferrous reaction system, then supplementing with a calcium source, and finally fusing with the first solution. First, the reaction fully generates iron phosphate, simulating the coordination mode of Fe and phosphate in actual mud; subsequently, tricalcium phosphate is added, which not only supplements the crucial Ca element in actual mud but also promotes the slow dissolution of tricalcium phosphate through the acidic environment provided by phosphoric acid, thus allowing Ca... 2+ The solution is uniformly dispersed and forms calcium phosphate precipitate with phosphate ions, preventing Ca from existing in a free or non-target form. Furthermore, the reagent ratios in this application are strictly determined based on the elemental analysis results of actual mud, ensuring that the content of core elements such as Fe, Ca, and P in the second solution highly matches the actual mud source term. This lays the foundation for the accuracy of the composition of the subsequent simulation system and solves the problem of large deviations between the phosphate system and reality.

[0040] In a specific embodiment, the method for converting the second solution into the third solution includes: based on the raw material ratio, mixing 2 kg to 8 kg of manganese dihydrogen phosphate dihydrate, 1 kg to 5 kg of boron anhydride, and 800 L to 1200 L of water evenly, and then adding the second solution to obtain the third solution. In actual intermediate-level radioactive α-chemical deposition mud, manganese (Mn) and boron (B) are important characteristic elements, and their content and form directly affect the chemical stability of the mud and the reaction behavior during treatment (such as oxidation characteristics during microwave calcination). Based on the elemental analysis results of actual mud, this application precisely introduces manganese and boron elements by controlling the ratio of manganese dihydrogen phosphate dihydrate and boron anhydride. Among them, manganese dihydrogen phosphate dihydrate, as a manganese source, can provide manganese ions (Mn) in the actual mud. 2+ The simulation employs a phosphate coordination environment with consistent chemical forms (simulating the binding state of manganese and phosphate in actual mud); boron anhydride dissolves in water to form boric acid, simulating the oxyacid form of boron in actual mud. The ratio of these two components strictly matches the elemental ratio of Mn to B in actual mud, ensuring that the concentrations of Mn and B in the third solution deviate controllably from the actual source terms. This overcomes the shortcomings of existing simulation methods that neglect minor elements such as manganese and boron, leading to incomplete chemical composition and enabling the simulation system to more comprehensively reflect the chemical characteristics of actual mud.

[0041] In a specific embodiment, the method for converting the third solution into a primary mother liquor includes: dissolving 3 kg to 4 kg of sodium metasilicate nonahydrate in 80 L to 120 L of water based on the raw material dosage ratio to obtain an aqueous solution of sodium metasilicate nonahydrate, then mixing it with the third solution, and obtaining the primary mother liquor after the precipitation of white flocculent matter. In actual moderately radioactive α-chemical deposition mud, silicates are key components constituting the mud's structural framework, and their content and form directly affect the mud's stability and compatibility during solidification treatment (such as the hydration reaction in cement solidification). This application uses sodium metasilicate nonahydrate as the silicon source; sodium metasilicate nonahydrate dissociates into SiO3 after dissolving in water. 2- It can react with the Fe already present in the third solution. 3+ Ca 2+ Mn 2+ and Nd 3+ (U) and other metal ions coordinate to generate silicate precipitates (such as iron silicate and calcium silicate) with the same morphology as those in actual mud, which completes the core chemical framework of silicon-metal ions in the simulation system. This solves the defect of neglecting silicon in existing simulation methods, which leads to large deviations in chemical composition from reality, and makes the simulation system closer to the chemical nature of real mud.

[0042] In a specific embodiment, the method for converting the primary mother liquor into simulated mud mother liquor includes: dissolving 1 kg of sodium aluminate in 10 L to 15 L of water based on the raw material dosage ratio to obtain a sodium aluminate aqueous solution, then mixing it with the primary mother liquor, and obtaining the simulated mud mother liquor after the precipitation of agglomerated flocs. In actual moderately radioactive α-chemical deposition mud, aluminum (existing in the form of aluminates, etc.) is a key component affecting the chemical stability and solidification characteristics of the mud (such as the compatibility of hydration reactions in cement solidification). This application uses sodium aluminate as the aluminum source, which dissociates into AlO2 after dissolving in water. - It can react with the Fe already present in the primary mother liquor. 3+ Ca 2+ Mn 2+ 、Nd 3+ (U) and SiO3 2- The equal components react to generate aluminate-silicate composite precipitates (such as iron aluminosilicate and calcium aluminosilicate) with the same structure as those in actual mud, thus completing the core chemical framework of aluminum-multi-component synergistic effect in the simulation system.

[0043] In a specific embodiment, the temperature of the evaporation and concentration process is 100℃~110℃, and the time is 1h~2h.

[0044] In a specific embodiment, the drying process is carried out at a temperature of 60°C to 90°C for a duration of more than 8 hours.

[0045] In a specific embodiment, during the preparation of the radioactive α-chemical deposition mud simulation system, the ratio of the simulated dry mud to water is 1 kg: (1 L ~ 4 L).

[0046] As a preferred embodiment of this application, a method for preparing a radioactive α-chemical deposition mud simulation system is provided, such as... Figure 2 As shown, it includes the following steps:

[0047] S101. Mix ferric nitrate nonahydrate, neodymium nitrate hexahydrate, and distilled water thoroughly and dissolve to obtain the first solution.

[0048] S102. Mix phosphoric acid, ferrous sulfate and distilled water evenly, dissolve them, add tricalcium phosphate, and then add it to the first solution and mix evenly to obtain the second solution.

[0049] S103. Mix manganese dihydrogen phosphate dihydrate, boron anhydride and distilled water in a certain proportion until dissolved, then add to the second solution and mix until dissolved to obtain the third solution.

[0050] S104. Dissolve sodium metasilicate nonahydrate in distilled water, add it to the third solution, and precipitate some white flocculent matter to obtain the primary mother liquor.

[0051] S105. Dissolve sodium aluminate in distilled water, add it to the primary mother liquor, shake, and precipitate agglomerated flocculent material to obtain simulated mud mother liquor.

[0052] S106. The simulated mud mother liquor is evaporated and concentrated to obtain simulated wet mud.

[0053] S107. Dry the simulated wet mud to obtain simulated dry mud.

[0054] S108. Based on the water content requirements of moderately radioactive alpha chemical deposition mud, distilled water was added to the simulated dry mud to obtain a simulated system of radioactive alpha chemical deposition mud.

[0055] The radioactive alpha chemical deposition mud simulation system in this application is a simulated mud. Simulated mud with different water contents can be prepared according to different water content requirements to obtain an experimental group, which is the experimental system.

[0056] In the above scheme, this application first prepares a ferric nitrate-neodymium solution to simulate the initial dissolved state of Fe and U elements in actual mud. Then, phosphoric acid, ferrous sulfate, and tricalcium phosphate are added to form a ferric phosphate-calcium system, simulating the initial reaction and precipitation of phosphates with metal ions in actual mud. Next, manganese-boron solution, sodium metasilicate solution, and sodium aluminate solution are added sequentially to simulate the gradual precipitation process of manganese salts, silicates, and aluminates in actual mud, respectively. By controlling the order and conditions of each stage of the reaction, the preparation process of this application ensures that the chemical precipitation formation path of the simulated mud is consistent with that of actual mud, avoiding the reaction chaos caused by mixing all reagents at once, thus ensuring a high degree of consistency between the chemical composition of the simulated mud and that of actual mud.

[0057] Secondly, based on a general inventive concept, this application also provides a radioactive alpha chemical deposition mud simulation system prepared by the above-mentioned preparation method.

[0058] In summary, this application has at least the following advantages:

[0059] (1) In view of the safety issues of personnel being exposed to radiation during experiments due to the presence of long-half-life alpha nuclides such as Pu and Am in actual moderately radioactive alpha chemical deposition mud, this application replicates the formation process of actual radioactive alpha chemical deposition mud by using non-radioactive chemical reagents combined with radioactive nuclide substitutes (such as neodymium replacing uranium) to synthesize a simulated mud system. The simulated system of this application is completely free of radioactive materials, yet it can maintain a chemical composition similar to that of actual mud. This not only meets the requirements of mud chemical properties for exploration experiments of treatment routes, but also fundamentally eliminates the risk of radiation exposure for experimental personnel in sample preparation, process operation, and data acquisition. It provides a safe experimental carrier for long-term, multi-batch treatment technology research and development experiments, and solves the technical problem of balancing safety and experimental requirements in radioactive waste experimental research.

[0060] (2) Given that actual radioactive alpha chemical deposition mud is radioactive waste, its off-site transportation is subject to strict regulations, high transportation costs, and complex procedures. Furthermore, the off-site testing of products from the treatment route faces challenges in ensuring radioactive compliance. The simulated mud system prepared in this application is non-radioactive and does not require adherence to the special transportation and testing management requirements for radioactive waste. On the one hand, it facilitates cross-regional transportation, supporting off-site engineering verification experiments of treatment technologies such as microwave calcination and cement solidification in different laboratories and engineering verification sites, breaking the limitation of experimental sites being confined to the radioactive waste generation location. On the other hand, various products generated from the treatment route (such as calcination residue and solidified bodies) can be directly sent for component analysis and physical performance testing without special protective measures, significantly reducing testing costs and time. This advantage effectively solves the difficulties of off-site experiments and product testing of actual mud, providing a feasible path for multi-scenario verification and comprehensive performance evaluation of treatment technologies.

[0061] (3) Given that existing simulation systems cannot replicate the physical properties of actual mud, resulting in experimental data that cannot support equipment design and process optimization, the simulated mud system of this application is highly consistent with the actual intermediate-level radioactive alpha chemical deposition mud in terms of physical properties (such as water content, density, fluidity, and viscosity). It can realistically simulate the physical behavior of actual mud in pipeline transportation (such as flow rate and resistance loss) and treatment processes (such as stirring and settling). Based on the experiments conducted using this simulated mud, the obtained equipment compatibility data (such as pump selection and pipeline diameter design) and process parameters (such as stirring rate and transportation pressure) can directly provide accurate basis for equipment development and process optimization in nuclear facility decommissioning and radioactive waste treatment projects. This avoids the problem of disconnect between laboratory data and engineering applications caused by the deviation between the simulation system and the physical properties of actual mud, thereby reducing the risks of equipment failure and process adjustment in actual engineering operations, reducing engineering construction and operation and maintenance costs, and laying a key foundation for the engineering implementation of treatment technology.

[0062] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.

[0063] The raw materials and their purities used in the following examples include: ferric nitrate nonahydrate AR (98.5%), neodymium nitrate hexahydrate AR (99.0%), phosphate AR (85.0%), ferrous sulfate AR (98.0%), tricalcium phosphate AR (99.0%), manganese dihydrogen phosphate dihydrate AR (99.0%), boron anhydride AR (98.0%), sodium metasilicate nonahydrate AR (98.0%), and sodium aluminate AR (98.0%).

[0064] Example 1

[0065] This embodiment provides a radioactive α-chemical deposition mud simulation system, which is prepared by the following method:

[0066] (1) Preparation of the first solution

[0067] Weigh 2.5 kg of ferric nitrate nonahydrate [Fe(NO3)3·9H2O] and dissolve it in 30 L of distilled water. After dissolution, add 6.3 kg of neodymium nitrate hexahydrate [Nd(NO3)3·6H2O]. After complete dissolution, the resulting solution is a clear reddish-brown first solution.

[0068] (2) Preparation of the second solution

[0069] Weigh 0.2 kg of phosphoric acid (H3PO4, density 1.685 kg / L) and dissolve it in 50 L of distilled water. After stirring evenly, add 0.05 kg of ferrous sulfate (FeSO4). After it is completely dissolved, add 0.1 kg of tricalcium phosphate [Ca3(PO4)2]. The solution is white and turbid.

[0070] Add all of the first solution prepared in step (1), and the mixed solution becomes clear with no obvious color change, which is the second solution.

[0071] (3) Preparation of the third solution

[0072] Weigh 0.2 kg of manganese phosphate dihydrate [Mn(H2PO4)2·2H2O] and dissolve it in 20 L of distilled water. After dissolution, add 0.064 kg of boron anhydride (B2O3). The solution is colorless and transparent.

[0073] After complete dissolution, add all of the second solution prepared in step (2), and the mixed solution becomes a clear, light purple third solution.

[0074] (4) Preparation of primary mother liquor

[0075] Weigh 0.66 kg of sodium metasilicate nonahydrate [Na2SiO3·9H2O] and dissolve it in 20 L of distilled water. After it is completely dissolved, add all of the third solution prepared in step (3). After standing, white flocculent matter appears. The solution with white flocculent matter is the primary mother liquor.

[0076] (5) Prepare simulated mud mother liquor

[0077] Weigh 4.17 kg of sodium aluminate (Na2Al2O4) and dissolve it in 50 L of distilled water. After complete dissolution, add all the primary mother liquor prepared in step (4). After standing, a large amount of agglomerated flocculent material appears. This solution with agglomerated flocculent material is the simulated mud mother liquor, and its photograph is shown below. Figure 1As shown in (a) above. Gently shaking the container disperses the agglomerated flocs. At this point, the pH of the simulated mud mother liquor is measured to be approximately 9, eliminating the need for alkalization with sodium hydroxide.

[0078] (6) Evaporation and concentration to simulate mud mother liquor

[0079] The simulated mud mother liquor was placed in an open beaker for evaporation to promote further mud formation. During evaporation, the temperature of the simulated mud mother liquor was adjusted to approximately 105°C using a heater, and evaporation was carried out at this temperature for about 1 hour, forming a mixture resembling... Figure 1 The simulated wet mud is shown in (b) of the image.

[0080] (7) Drying simulated wet mud

[0081] The simulated wet mud was placed in a drying oven and dried thoroughly at 105°C to obtain simulated dry mud with a mass of 12.02g. Water was added to the simulated dry mud according to the water content of moderate radioactive alpha chemical deposition mud to prepare a simulated system of radioactive alpha chemical deposition mud.

[0082] Compared with the simulated wet mud obtained in step (6), the weight loss rate (mass moisture content) is about 44%. Among them, the mass moisture content of the source wet mud is 60%~70%, so the moisture content error of the simulated wet mud is 16%~26%, which can be adjusted by adding water, meeting the project requirements. Figure 1 (c) in the image is a real picture of the simulated dry mud after grinding.

[0083] (8) Component analysis

[0084] During mud preparation, various precipitates are generated at different rates, resulting in poor homogeneity of mud composition. Therefore, analytical results obtained from samples taken from larger batches of prepared mud are not representative. To address this, simulated mud composition analysis is based on synthesizing a small amount of mud and ensuring its complete dissolution. Specific steps include:

[0085] 8.1) Dissolving Reverse Aqua Regulator: Gradually and slowly add 240 mL of reverse aqua regulator (65 wt% concentrated nitric acid to 37 wt% concentrated hydrochloric acid in a volume ratio of 3:1) to the total 12.02 g of the dry precipitate obtained above, and heat and stir at a stable heat source of 70°C for about 2 hours to dissolve. The solution is brownish-red, and a large amount of flocculent matter is produced after cooling. After placing it in a separatory funnel and allowing it to stand for a sufficient time (>12 h), a small amount of insoluble matter and flocculent matter will form in the lower part of the funnel, resulting in the reverse aqua regulator solution.

[0086] 8.2) Separation of flocculent matter: Cool the obtained aqua regia solution to room temperature, centrifuge at 3000 r / min for 20 s, take out all the supernatant, dilute with deionized water to a final volume of 500 mL, and obtain sample 1.

[0087] 8.3) Dissolution of flocculent matter: Slowly add 300 mL of 30 wt% hydrogen peroxide to the flocculent matter separated by centrifugation and the supernatant obtained above, and heat and stir in a 50°C water bath for 1 hour. Then stop heating and continue stirring until the solution temperature drops to room temperature. Transfer the solution to a volumetric flask and dilute to 500 mL with deionized water to obtain sample 2.

[0088] 8.4) Sample Analysis: Inductively Coupled Plasma Emission Spectroscopy (ICP-OES, Optima 8000, PerkinElmer Inc.) was performed on Sample 1 and Sample 2 respectively. The concentrations of each element obtained were combined as the actual concentrations of the corresponding elements in the simulated dry mud.

[0089] Two sets of experiments were conducted to compare the relevant element concentrations of the simulated dry mud prepared according to the preparation steps in this embodiment with those of the source dry mud. The concentration errors of the most abundant elements, such as Fe, Al, and Nd (substituted for U), in the simulated dry mud of Example 1 were all within ±5%, which meets the requirements for simulated mud preparation.

[0090] Example 2

[0091] This embodiment provides a radioactive α-chemical deposition mud simulation system, which is prepared by the following method:

[0092] (1) Preparation of the first solution

[0093] Weigh 3 kg of ferric nitrate nonahydrate [Fe(NO3)3·9H2O] and dissolve it in 30 L of distilled water. After dissolution, add 6.3 kg of neodymium nitrate hexahydrate [Nd(NO3)3·6H2O]. After complete dissolution, the resulting solution is a clear reddish-brown first solution.

[0094] (2) Preparation of the second solution

[0095] Weigh 0.2 kg of phosphoric acid (H3PO4, density 1.685 kg / L) and dissolve it in 50 L of distilled water. After stirring evenly, add 0.05 kg of ferrous sulfate (FeSO4). After it is completely dissolved, add 0.1 kg of tricalcium phosphate [Ca3(PO4)2]. The solution is white and turbid.

[0096] Add all of the first solution prepared in step (1), and the mixed solution becomes clear with no obvious color change, which is the second solution.

[0097] (3) Preparation of the third solution

[0098] Weigh 0.1 kg of manganese phosphate dihydrate [Mn(H2PO4)2·2H2O] and dissolve it in 20 L of distilled water. After dissolution, add 0.07 kg of boron anhydride (B2O3). The solution is colorless and transparent.

[0099] After complete dissolution, add all of the second solution prepared in step (2), and the mixed solution becomes a clear, light purple third solution.

[0100] (4) Preparation of primary mother liquor

[0101] Weigh 0.76 kg of sodium metasilicate nonahydrate [Na2SiO3·9H2O] and dissolve it in 20 L of distilled water. After it is completely dissolved, add all of the third solution prepared in step (3). After standing, white flocculent matter appears. The solution with white flocculent matter is the primary mother liquor.

[0102] (5) Prepare simulated mud mother liquor

[0103] Weigh 4.02 kg of sodium aluminate (Na2Al2O4) and dissolve it in 50 L of distilled water. After complete dissolution, add all the primary mother liquor prepared in step (4). After standing, a large amount of agglomerated flocculent material appears. This solution containing agglomerated flocculent material is the simulated mud mother liquor. Gently shake the container to disperse the agglomerated flocculent material. At this time, the pH of the simulated mud mother liquor is measured to be approximately 9, and alkalization with sodium hydroxide is not required.

[0104] (6) Evaporation and concentration to simulate mud mother liquor

[0105] The simulated mud mother liquor was placed in an open beaker for evaporation to promote further mud formation. During evaporation, the temperature of the simulated mud mother liquor was adjusted to approximately 105°C using a heater, and evaporation was carried out at this temperature for about 1 hour to form simulated wet mud.

[0106] (7) Drying simulated wet mud

[0107] The simulated wet mud was placed in a drying oven and dried thoroughly at 105°C to obtain simulated dry mud with a mass of 15.19g. Water was added to the simulated dry mud according to the water content of moderate radioactive alpha chemical deposition mud to prepare a simulated system of radioactive alpha chemical deposition mud.

[0108] Compared with the simulated wet mud obtained in step (6), the weight loss rate (mass moisture content) is about 48%. Among them, the mass moisture content of the source wet mud is 60%~70%, so the moisture content error of the simulated wet mud is 12%~22%, which can be adjusted by adding water, which meets the project requirements.

[0109] (8) Component analysis

[0110] During mud preparation, various precipitates are generated at different rates, resulting in poor homogeneity of mud composition. Therefore, analytical results obtained from samples taken from larger batches of prepared mud are not representative. To address this, simulated mud composition analysis is based on synthesizing a small amount of mud and ensuring its complete dissolution. Specific steps include:

[0111] 8.1) Dissolving Reverse Aqua Regulator: Gradually and slowly add 240 mL of reverse aqua regulator (volume ratio of 65 wt% concentrated nitric acid to 37 wt% concentrated hydrochloric acid = 3:1) to the total dry precipitate of 15.19 g obtained above, and heat and stir at a stable heat source of 70 °C for about 2 hours to dissolve. The solution is brownish-red, and a large amount of flocculent matter is produced after cooling. After placing it in a separatory funnel and allowing it to stand for a sufficient time (>12 h), a small amount of insoluble matter and flocculent matter will form in the lower part of the funnel, resulting in the reverse aqua regulator solution.

[0112] 8.2) Separation of flocculent matter: Cool the obtained aqua regia solution to room temperature, centrifuge at 3000 r / min for 20 s, take out all the supernatant, dilute with deionized water to a final volume of 500 mL, and obtain sample 1.

[0113] 8.3) Dissolution of flocculent matter: Slowly add 300 mL of 30 wt% hydrogen peroxide to the flocculent matter separated by centrifugation and the supernatant obtained above, and heat and stir in a 50°C water bath for 1 hour. Then stop heating and continue stirring until the solution temperature drops to room temperature. Transfer the solution to a volumetric flask and dilute to 500 mL with deionized water to obtain sample 2.

[0114] 8.4) Sample Analysis: Inductively Coupled Plasma Emission Spectroscopy (ICP-OES, Optima 8000, PerkinElmer Inc.) was performed on Sample 1 and Sample 2 respectively. The concentrations of each element obtained were combined as the actual concentrations of the corresponding elements in the simulated dry mud.

[0115] Two sets of experiments were conducted to compare the relevant element concentrations of the simulated dry mud prepared according to the preparation steps in this embodiment with those of the source dry mud. The concentration errors of the most abundant elements, such as Fe, Al, and Nd (substituted for U), in the simulated dry mud of Example 2 were all within ±10%, which meets the requirements for simulated mud preparation.

[0116] Comparative Example

[0117] This comparative example provides a radioactive α-chemical deposition mud simulation system, which is prepared by the following method:

[0118] (1) Preparation of mother liquor

[0119] Weigh 2.5 kg of ferric nitrate nonahydrate [Fe(NO3)3·9H2O] and dissolve it in 30 L of distilled water. After dissolution, add 6.3 kg of neodymium nitrate hexahydrate [Nd(NO3)3·6H2O]. After complete dissolution, the resulting solution is a clear reddish-brown solution A.

[0120] Weigh 0.2 kg of phosphoric acid (H3PO4, density 1.685 kg / L) and dissolve it in 50 L of distilled water. After stirring evenly, add 0.05 kg of ferrous sulfate (FeSO4). After it is completely dissolved, add 0.1 kg of tricalcium phosphate [Ca3(PO4)2]. The solution is white and turbid, which is solution B.

[0121] Weigh 0.2 kg of manganese phosphate dihydrate [Mn(H2PO4)2·2H2O] and dissolve it in 20 L of distilled water. After dissolution, add 0.064 kg of boron anhydride (B2O3). The resulting solution is a colorless and transparent solution C.

[0122] Weigh 0.66 kg of sodium metasilicate nonahydrate [Na2SiO3·9H2O] and dissolve it in 20 L of distilled water. After complete dissolution, a colorless and transparent solution D is obtained.

[0123] Weigh 4.17 kg of sodium aluminate (Na2Al2O4) and dissolve it in 50 L of distilled water. After complete dissolution, a colorless and transparent solution E is obtained.

[0124] Mix solutions A, B, C, D, and E thoroughly, and let stand. A brown flocculent precipitate will form. The solution containing the brown flocculent precipitate is the mother liquor of this comparative example.

[0125] (2) Simulated mud evaporation

[0126] The mother liquor was placed in an open beaker for evaporation to promote further mud formation. During evaporation, the temperature of the mother liquor was adjusted to approximately 105°C using a heater, and evaporation was carried out at this temperature for about 1 hour to form simulated wet mud.

[0127] (3) Simulated drying of wet mud

[0128] The simulated wet mud was placed in a drying oven and dried thoroughly at 105°C to obtain simulated dry mud with a mass of 9.81g. Compared with the simulated wet mud prepared above, the weight loss rate (mass moisture content) was approximately 32%. The mass moisture content of the original wet mud was 60%~70%, so the moisture content error of the simulated wet mud was 28%~38%, and the weight loss rate was much greater than that of real mud evaporation and drying.

[0129] (4) Component analysis

[0130] According to the method in Example 1, the content of the target elements Fe, Al and Nd (substitute U) in the simulated dry mud of this comparative example is much lower than that of the source term, only 40% to 70% of the element content of the original real mud, which does not meet the requirements for the preparation of simulated mud.

[0131] In summary, we can conclude that:

[0132] (1) This application achieves a high degree of consistency between the core element concentrations of the simulated dry mud and the actual source terms through staged reactions and reagent ratio control. In Example 1, the concentration errors of major elements such as Fe, Al, and Nd (substitute for U) are only ±5%, and in Example 2, the error is controlled within ±10%, both meeting the core requirements of simulated mud for component accuracy. In contrast, the comparative example suffers from disordered reactions due to one-time reagent mixing, and the core element content is only 40%~70% of the actual source terms, which is completely unsupportable for the treatment technology experiment. This advantage ensures that the simulated mud can truly reproduce the chemical behavior of the actual mud during the treatment process (such as the oxidation reaction in microwave calcination and the solubility characteristics in acid dissolution degradation), providing a reliable experimental platform for parameter optimization (such as calcination temperature and acid dosage) of cement solidification, microwave calcination and other technical routes, and avoiding experimental data distortion caused by the deviation between the simulated system and the actual composition.

[0133] (2) The physical properties (moisture content, flocculent structure, and dispersibility) of the simulated mud in this application can be accurately adapted to actual engineering scenarios. Among them, the moisture content can be flexibly adjusted. The weight loss rate (mass moisture content) of the simulated wet mud in Example 1 is 44%, which can be adjusted to 60%~70% of the actual source by adding water, with an error of only 16%~26%. The error in Example 2 is further reduced to 12%~22%, which is far better than the moisture content error of 28%~38% in the comparative example, ensuring that the physical behavior of the simulated mud in the processes of static settling and mixing is consistent with reality. The flocculent structure is adapted to engineering operations. The agglomerated flocculents of the simulated mud can be dispersed by vibration, which can truly simulate the flow resistance of the actual mud in pipeline transportation and the dispersion effect in equipment mixing. It provides a direct reference for pump selection, pipeline diameter design, and mixing rate optimization in the decommissioning of nuclear facilities, reducing the risk of equipment blockage and poor transportation in actual engineering. In contrast, the brown flocculent sediment structure generated in the comparative example is rigid and cannot simulate such physical behavior.

[0134] (3) This application uses neodymium instead of uranium, and the simulated mud contains no α nuclides such as Pu and Am. Experimenters do not need special protection during sample preparation, process operation and data acquisition, and long-term, multi-batch experiments can be carried out. In contrast, experiments with actual mud require strict control of irradiation dose, and the experimental cycle and operational flexibility are limited. Furthermore, the non-radioactive simulated mud does not need to comply with the transportation control requirements for radioactive waste (such as special transport vehicles and radiation monitoring equipment), and can easily realize cross-regional engineering verification (such as transporting from the laboratory to the engineering verification site). At the same time, the processing products of the simulated mud (such as calcination residue) can be directly sent for testing without special radiation protection measures, thereby greatly reducing the testing cost and cycle.

[0135] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of this application.

[0136] Finally, it should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0137] This application uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for preparing a radioactive α-chemical deposition mud simulation system, characterized in that, Includes the following steps: Based on the elemental analysis results of the moderately radioactive alpha chemical deposition mud, the proportion of raw materials used to prepare the simulated mud was calculated. Based on the aforementioned raw material ratio, a first solution is prepared using ferric nitrate nonahydrate, neodymium nitrate hexahydrate, and water as raw materials. The first solution is then gradually prepared into a simulated mud mother liquor according to a preset procedure. The simulated mud mother liquor was subjected to evaporation and concentration treatment and drying treatment in sequence to obtain simulated dry mud. Based on the water content of the moderately radioactive alpha chemical deposition mud, water was added to the simulated dry mud to prepare a simulated system of radioactive alpha chemical deposition mud; wherein... The preset steps include: based on the raw material usage ratio, converting the first solution into the simulated mud mother liquor according to the conversion path of the first solution, the second solution, the third solution, the primary mother liquor, and the simulated mud mother liquor; The method for converting the first solution into the second solution includes: based on the raw material ratio, mixing phosphoric acid, ferrous sulfate and water evenly, and then adding tricalcium phosphate and the first solution sequentially to obtain the second solution; The method for converting the second solution into the third solution includes: based on the raw material ratio, mixing manganese dihydrogen phosphate dihydrate, boron anhydride and water evenly, then adding the second solution to obtain the third solution; The method for converting the third solution into a primary mother liquor includes: mixing the sodium metasilicate nonahydrate aqueous solution with the third solution based on the raw material dosage ratio, and obtaining the primary mother liquor after the precipitation of white flocculent matter; The method for converting the primary mother liquor into simulated mud mother liquor includes: mixing sodium aluminate aqueous solution with the primary mother liquor based on the raw material dosage ratio, and obtaining the simulated mud mother liquor after the precipitation of agglomerated flocs.

2. The method for preparing the radioactive α-chemical deposition mud simulation system according to claim 1, characterized in that, The ratio of ferric nitrate nonahydrate, neodymium nitrate hexahydrate, and water in the first solution is 2.5 kg: 6.3 kg: 30 L or 3 kg: 6.3 kg: 30 L.

3. The method for preparing the radioactive α-chemical deposition mud simulation system according to claim 1, characterized in that, The ratio of phosphoric acid, ferrous sulfate, tricalcium phosphate, and water is 0.2 kg: 0.05 kg: 0.1 kg: 50 L.

4. The method for preparing the radioactive α-chemical deposition mud simulation system according to claim 1, characterized in that, The ratio of manganese dihydrogen phosphate dihydrate, boron anhydride, and water is (2kg~8kg): (1kg~5kg): (800L~1200L).

5. The method for preparing the radioactive α-chemical deposition mud simulation system according to claim 1, characterized in that, The ratio of sodium metasilicate nonahydrate to water in the sodium metasilicate nonahydrate aqueous solution is (3kg~4kg): (80L~120L).

6. The method for preparing the radioactive α-chemical deposition mud simulation system according to claim 1, characterized in that, The ratio of sodium aluminate to water in the sodium aluminate aqueous solution is 1 kg: (10 L~15 L).

7. The method for preparing the radioactive α-chemical deposition mud simulation system according to claim 1, characterized in that, The evaporation and concentration process is carried out at a temperature of 100℃~110℃ for 1h~2h.

8. The method for preparing the radioactive α-chemical deposition mud simulation system according to claim 1, characterized in that, The drying process is carried out at a temperature of 105°C for a duration of more than 8 hours.

9. The method for preparing the radioactive α-chemical deposition mud simulation system according to claim 1, characterized in that, In the preparation of the radioactive α-chemical deposition mud simulation system, the ratio of simulated dry mud to water is 1 kg: (1 L ~ 4 L).

10. A radioactive α-chemical deposition mud simulation system, characterized in that, Obtained by the preparation method according to any one of claims 1-9.

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