A linear electrode plating cell and plating method for high resolution alpha spectrometry uranium isotope measurement sample preparation

Abstract

The application discloses a linear electrode plating cell and a plating method for sample preparation of high-resolution alpha spectrum uranium isotope measurement, and belongs to the technical field of uranium isotope measurement. The plating cell comprises a lower bottom, a plating sheet, a plating cell and an anode which are coaxially arranged from bottom to top. The plating sheet is a circular cathode carrier, and the effective electrodeposition area is a circular area with a diameter of 5 mm. The plating method comprises the following steps: pretreatment of a sample nitric acid and sodium sulfate, use of an ammonium sulfate buffer solution, constant current plating of 0.15 A for 2 h with an optimal uranium sample loading amount of less than or equal to 10 mu g, and addition of ammonia water at the end of plating to stabilize the plating layer. The linear electrode has the advantages of simple structure and easy standardization and mass production, can inhibit the edge effect of plating and reduce alpha self-absorption, and when 4 mu g of natural uranium is used as a source, the energy peak half-width of uranium-238 is less than 10 keV, the standard deviation is 1.9 keV, the activity ratio of uranium-238 / uranium-234 is 1.04, the standard deviation is 0.05, the adjacent energy peaks of uranium-234, uranium-235 and uranium-238 can be clearly distinguished, and the measurement precision and accuracy of the uranium isotope alpha spectrum are greatly improved.

Description

Technical Field

[0001] This application belongs to the field of uranium isotope measurement technology, and specifically relates to a linear electrode electroplating cell and electroplating method for preparing samples for high-resolution alpha spectrum uranium isotope measurement. Background Technology

[0002] Alpha spectroscopy is currently the core detection method for quantitative measurement of uranium isotopes, and it is widely used in environmental monitoring, nuclide analysis, and radioactivity detection. In alpha spectroscopy detection systems, alpha particles have weak penetrating power and are prone to self-absorption effects. To obtain accurate uranium isotope detection results, it is necessary to prepare a thin and highly uniform uranium electroplating source. Among these, excellent energy resolution is the core key to ensuring accurate measurement of uranium isotope alpha spectra.

[0003] Natural uranium mainly comprises three isotopes: uranium-238, uranium-235, and uranium-234. The corresponding alpha ion energies for these three isotopes are 4198 keV, 4395 keV, and 4775 keV, respectively, with very similar energy ranges. However, the inherent energy resolution of alpha spectrometers is relatively low. If the uniformity of the accompanying uranium electroplating source is substandard, it will directly cause peak broadening and overlap in the energy spectrum, completely masking the weakest characteristic energy peak of uranium-235. This makes effective identification and accurate quantification impossible, significantly reducing the precision and accuracy of uranium isotope measurements.

[0004] Existing research and testing practices indicate that, in addition to the hardware performance of the alpha spectrometer itself, the quality of the electroplating source is the most critical factor determining the energy resolution of the alpha spectrum. The quality of the electroplating source directly depends on the structural design of the electroplating bath and the associated electroplating process parameters. Currently, mainstream electroplating baths can be divided into four categories based on electrode type. Among them, linear electrode electroplating baths, with their advantages of simple structure, convenient assembly, ease of standardization and mass production, strong adaptability, and high scalability, have become the most widely used equipment in laboratory uranium isotope source preparation scenarios.

[0005] Existing equipment generally adopts a large-size plating sheet structure that matches the bottom area of ​​the plating bath, and its original design intention is to meet... 239+240 Pu、 241 This structure is suitable for detecting uranium nuclides such as Am, and is well-suited for low-energy resolution detection scenarios. However, it suffers from severe edge effects during electroplating, resulting in a Gaussian deposition pattern of uranium nuclides on the cathode surface. The deposition density decreases rapidly from the center to the edge, leading to extremely poor uniformity in the final uranium electroplating source.

[0006] The aforementioned defects result in uranium sample sources prepared by traditional linear electrode electroplating cells exhibiting significant alpha particle self-absorption effects and poor energy spectrum resolution. They are unable to distinguish adjacent energy peaks of uranium-234, uranium-235, and uranium-238, making it difficult to meet the requirements for high-precision and high-accuracy alpha spectrum measurement of uranium isotopes. This severely limits the application of linear electrode electroplating cells in the field of high-precision uranium isotope detection. Summary of the Invention

[0007] The purpose of this application is to provide a linear electrode electroplating cell and electroplating method for preparing samples for high-resolution alpha spectrum uranium isotope measurement. By optimizing the core structure of the linear electrode electroplating cell and reducing the effective electroplating deposition area, the problem of uneven uranium coating deposition is solved. At the same time, by matching exclusive electroplating process parameters, the energy resolution of alpha spectrum measurement is effectively improved, and the problems of low accuracy and poor precision of uranium isotope measurement in traditional equipment are solved.

[0008] To achieve the above objectives, this application provides a linear electrode electroplating cell for preparing samples for high-resolution alpha spectrum uranium isotope measurement. The cell includes a lower base, a plating sheet, a plating pool, and an anode, arranged coaxially from bottom to top. The plating sheet is a circular cathode carrier, and the effective electrodeposition area is a circular region with a diameter of 5 mm, resulting in an effective plating area of ​​1.13 cm². 2 The electroplating bath is adapted for electrodeposition of microgram-level uranium samples, and is used to improve the uniformity of uranium coating deposition, reduce alpha particle self-absorption, and optimize alpha spectrum energy resolution.

[0009] Furthermore, both the bottom plate and the plated sheet are made of conductive metal, and the plating bath is made of polytetrafluoroethylene.

[0010] Furthermore, the anode includes a centrally located Pt conductive wire and a polytetrafluoroethylene insulating cap located above the Pt conductive wire; the diameter of the Pt conductive wire is 0.2 cm, the effective electroplating length is 7.8 cm, and the outer diameter of the polytetrafluoroethylene insulating cap is 2.8 cm.

[0011] Furthermore, the plating bath has an inner diameter of 1.4cm, an outer diameter of 2.0cm, and a height of 8.0cm; the bottom diameter is 2.6cm, and the diameter of the center bearing surface of the bottom is 1.2cm.

[0012] Furthermore, the diameter of the plated sheet is 1.2 cm and the thickness is 0.2 cm. It is made of acid-resistant, highly conductive, and smooth-surfaced metallic materials and can stably withstand acidic electroplating environments with a pH of 1.5~3.

[0013] This application also provides an electroplating method for preparing samples for high-resolution alpha spectrum uranium isotope measurement, which uses a linear electrode electroplating cell and includes the following steps: S1. Coaxial assembly: The bottom, plating sheet, plating tank and anode of the linear electrode electroplating tank are coaxially assembled from bottom to top to obtain the linear electrode electroplating tank; S2. Uranium sample pretreatment: The purified uranium sample is evaporated to dryness, dissolved by heating with concentrated nitric acid, evaporated to near dryness, and then sodium sulfate solution is added to continue evaporation until it is wet salt, thus obtaining the pretreated sample; S3. Preparation of electroplating system: Add ammonium sulfate buffer solution to the pretreated sample to obtain the electroplating reaction system; S4. Constant current electroplating: Connect the positive terminal of the electroplating power supply to the anode of the linear electrode electroplating tank and the negative terminal to the bottom of the linear electrode electroplating tank. Electroplating is carried out for 2 hours under constant current conditions to allow uranyl ions to migrate in a directional manner and deposit on the surface of the plated sheet. S5. Post-solidification treatment: Add ammonia water 1 minute before the end of electroplating. After electroplating is completed, remove the linear electrode electroplating tank, rinse the plated sheet with ethanol and air dry it naturally to obtain the uranium isotope electroplating source.

[0014] Furthermore, in step S2, the concentration of concentrated nitric acid is 68 wt%, the volume is 1 mL, and the near-dry state is a state without free liquid droplets and without flow; the concentration of sodium sulfate solution is 0.3 mol / L, and the volume is 1 mL.

[0015] Furthermore, the pH value of the ammonium sulfate buffer solution is 2.1~2.3, the sulfate concentration is 1 mol / L, and the volume is 10 mL.

[0016] Furthermore, in step S4, the constant current is 0.15A, the effective deposition area of ​​the plating sheet is 5mm in diameter, the uranium content in the pretreated sample is ≤10μg, and the sample loading amount is controlled by the uranium content in the pretreated sample. The effective deposition area refers to the circular, confined surface of the plating sheet surface that, after being shielded and restricted, is the only surface exposed to the electroplating solution where uranyl ions can undergo electrochemical reduction to generate a solid uranium coating.

[0017] Furthermore, in step S5, the amount of ammonia added is 1 mL, and the concentration is 28wt%~29wt%.

[0018] In summary, this application has the following beneficial effects: This application provides a linear electrode electroplating cell for preparing samples for high-resolution alpha spectrum uranium isotope measurement. The cell comprises a bottom, plating sheet, plating tank, and anode, arranged coaxially from bottom to top. Compared to irregularly shaped electrodes such as spiral electrodes and mesh electrodes, this design is simpler, easier to manufacture, and easier to assemble and disassemble, facilitating standardized mass production and routine laboratory use. It overcomes the limitations of irregularly shaped electrodes, such as complex manufacturing, difficulty in large-scale standardization, and limited application. Furthermore, the components utilize differentiated materials: the plating tank is made of acid-resistant insulating polytetrafluoroethylene (PTFE), the cathode plating sheet and bottom are made of conductive metal, and the anode uses platinum wire with a PTFE insulating cap. This ensures both cathode conductivity and electric field distribution constraint through insulation, optimizing coating uniformity through a synergistic effect of material and structure.

[0019] This application provides an electroplating method for preparing samples for high-resolution alpha spectrum uranium isotope measurement. The method is set with a small-area cathode structure, a sample loading amount of ≤10μg, and a constant current electroplating parameter of 0.15A. Parallel verification experiments were carried out using 4μg of natural uranium as a typical sample loading amount. The full width at half maximum (FWHM) of the characteristic alpha spectrum of uranium-238 corresponding to the obtained uranium electroplating source is less than 10keV, and the standard deviation of the FWHM test is only 1.9keV. The spectrum has a narrow peak shape and excellent resolution. At the same time, the measured uranium-238 / uranium-234 activity ratio is 1.04, and the standard deviation of the activity ratio is as low as 0.05. The test results are highly consistent with the theoretical state of radioactivity equilibrium of natural uranium. The reason for this is that this application limits the effective electrodeposition area of ​​the coating to a central circular area with a diameter of 5 mm, which greatly suppresses the edge effect inherent in linear electroplating, reduces the radial deposition difference of uranium coating, reduces alpha particle self-absorption, and overcomes the drawbacks of traditional large effective area coatings with Gaussian distribution, uneven thickness, and severe broadening of the energy spectrum. It can clearly distinguish the characteristic energy peaks of uranium-234, uranium-235, and uranium-238 with adjacent energies, avoids the uranium-235 energy peak being masked and unidentifiable, and significantly improves the accuracy and stability of quantitative measurement of uranium isotope activity. Attached Figure Description

[0020] 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.

[0021] Figure 1 This is a schematic diagram of the structure of the linear electrode electroplating cell proposed in the embodiments of this application.

[0022] Figure 2 This is a top view of the electroplating tank anode proposed in the embodiments of this application.

[0023] Figure 3 This is a front view of the anode of the electroplating tank according to an embodiment of this application.

[0024] Figure 4 This is a top view of the plating tank in the electroplating tank structure proposed in the embodiments of this application.

[0025] Figure 5 This is a front view of the plating tank in the electroplating tank structure proposed in the embodiments of this application.

[0026] Figure 6 This is a top view of the plated sheet in the electroplating tank structure proposed in the embodiments of this application.

[0027] Figure 7 This is a front view of the plated sheet in the electroplating tank structure proposed in the embodiments of this application.

[0028] Figure 8 This is a top view of the bottom of the electroplating tank structure proposed in the embodiments of this application.

[0029] Figure 9 This is a front view of the bottom of the electroplating tank structure proposed in the embodiments of this application.

[0030] Figure 10 The α spectrum is obtained by measuring different uranium contents after electroplating, as presented in the experimental examples of this application.

[0031] Figure 11 It is the full width at half maximum (FWHM) of uranium-238 in the α spectrum of the coated sheet obtained under different current conditions as presented in the experimental examples of this application.

[0032] Figure 12 It is the activity ratio of uranium-238 / uranium-234 in the α spectrum of the coating obtained under different current conditions as proposed in the experimental examples of this application.

[0033] Figure 13 This is a comparison chart of the standard deviation of radioactivity distribution in different shrinkage analysis regions of the linear electrode electroplating source proposed in the experimental examples of this application.

[0034] Figure 14 This is a high-resolution α-energy spectrum of uranium isotopes under 0.15A conditions proposed in the experimental examples of this application.

[0035] Figure 15 This is a schematic diagram of the α-energy spectrum of uranium isotopes electroplated onto a large effective area linear electrode as presented in the experimental example of this application. Detailed Implementation

[0036] 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.

[0037] In a first aspect, this application provides a linear electrode electroplating cell for preparing samples for high-resolution alpha spectrum uranium isotope measurement, comprising a lower base, a plating sheet, a plating pool, and an anode arranged coaxially from bottom to top. The plating sheet is a circular cathode carrier, and the effective electrodeposition area is a circular region with a diameter of 5 mm, resulting in an effective plating area of ​​1.13 cm². 2 The electroplating bath is adapted for electrodeposition of microgram-level uranium samples, and is used to improve the uniformity of uranium coating deposition, reduce alpha particle self-absorption, and optimize alpha spectrum energy resolution.

[0038] The electroplating tank of this application adopts a top-to-bottom coaxial layout of the bottom, plating sheet, plating tank, and anode, ensuring good assembly alignment and uniform electric field distribution in the electroplating space. This avoids local electric field distortion caused by eccentricity, improving the problem of uneven coating from the source. Furthermore, the linear structure is simple, and the parts are easy to process and disassemble, facilitating standardized mass production and widespread application in the laboratory. The effective electrodeposition area of ​​this application is limited to a small circle with a diameter of 5mm at the center, reducing the effective deposition range of the cathode, significantly weakening the edge enrichment effect inherent in traditional linear electrodes, breaking the radial Gaussian uneven deposition law of the coating, and reducing the thickness difference of the uranium coating; effectively reducing the self-absorption loss of alpha particles inside the coating, compressing the broadening of the energy spectrum peaks, and achieving effective separation of adjacent alpha energy peaks of uranium-234, uranium-235, and uranium-238, improving the energy resolution of the alpha spectrum and the quantitative accuracy of isotopes; limited to 1.13cm. 2 The effective electroplating area can accurately match the microgram-level uranium loading amount, avoiding self-absorption deterioration caused by excessively thick plating.

[0039] In this specific implementation, both the substrate and the plating sheet are made of conductive metals, such as stainless steel, platinum, or industrial titanium. This ensures continuous conductivity and low internal resistance in the cathode circuit, uniform potential on the cathode plate surface, and a consistent reduction rate of uranyl ions throughout the cathode, facilitating uniform deposition of the plating layer. Furthermore, the metal substrate has high mechanical strength and is resistant to deformation after repeated disassembly and reassembly. The plating bath is made of polytetrafluoroethylene (PTFE), which is resistant to strong acid corrosion and can withstand long-term use in acidic electroplating systems with a pH of 1.5–3. It will not be corroded by the electroplating buffer solution, preventing impurities from contaminating the uranium source. Its excellent insulation properties isolate stray leakage current from the sidewalls and concentrate the electric field on the effective deposition area of ​​the plating sheet, further suppressing ineffective deposition at the edges. Moreover, its chemical stability and dimensional stability are not easily affected by acidic or alkaline environments, ensuring consistent plating bath dimensions and facilitating standardized reproduction of experimental conditions.

[0040] In a specific embodiment, the anode comprises a centrally located Pt conductive wire and a polytetrafluoroethylene (PTFE) insulating cap above the Pt conductive wire. The central platinum (Pt) wire is chemically inert, does not dissolve or participate in electrochemical reactions in acidic electroplating systems, and its dimensions remain stable over the long term. The electric field morphology is not altered by corrosion, and platinum's excellent conductivity ensures uniform current density throughout the entire length. The upper PTFE insulating cap provides insulation and sealing to the upper end of the anode, constraining the electric field to distribute only downwards along the effective plating length of the Pt wire. This prevents the lateral dispersion of stray electric fields at the upper end, concentrating the electric field above the effective deposition area of ​​the plating sheet, reducing useless sidewall deposition, and further improving the uniformity of uranium deposition in the target area. Preferably, the diameter of the Pt conductive wire is 0.2 cm, the effective plating length is 7.8 cm, and the outer diameter of the PTFE insulating cap is 2.8 cm.

[0041] In a specific embodiment, the plating bath has an inner diameter of 1.4 cm, an outer diameter of 2.0 cm, and a height of 3.0 cm; the bottom has a diameter of 2.6 cm, and the diameter of the center bearing surface of the bottom is 1.2 cm. The plating sheet has a diameter of 1.2 cm and a thickness of 0.2 cm.

[0042] Secondly, based on a general inventive concept, this application also provides an electroplating method for preparing samples for high-resolution alpha spectrum uranium isotope measurement, which requires the use of the linear electrode electroplating cell described in the first aspect. The method includes the following steps: S1. Coaxial assembly: The bottom, plating sheet, plating tank and anode of the linear electrode electroplating tank are coaxially assembled from bottom to top to obtain the linear electrode electroplating tank.

[0043] S2. Uranium sample pretreatment: The purified uranium sample is evaporated to dryness, dissolved by heating with concentrated nitric acid, evaporated to near dryness, and then sodium sulfate solution is added to continue evaporation until it is wet salty, thus obtaining the pretreated sample.

[0044] In this specific implementation, the concentrated nitric acid concentration is 68% (mass fraction), and the volume is 1 mL, in a near-dry state (no free droplets, no flow); the sodium sulfate solution concentration is 0.3 mol / L, and the volume is 1 mL. First, the sample is digested with concentrated nitric acid to dissolve solid uranium salts. Excess nitric acid is removed by heating and volatilization, preventing residual strong acid from altering the pH of the subsequent buffer solution and disrupting the acid-base balance of the electroplating system. Then, the sodium sulfate solution introduces sulfate ions as a supporting electrolyte, pre-converting uranium into stable uranyl ions, improving the conductivity of the electroplating solution, reducing ohmic voltage drop and concentration polarization during electroplating, facilitating the stable and directional migration of uranyl ions, and reducing localized unevenness in coating thickness. Simultaneously, it removes volatile impurities from the sample, preventing impurity co-deposition that contaminates the uranium electroplating source and degrades the energy dispersive spectroscopy resolution.

[0045] S3. Preparation of the electroplating system: Add ammonium sulfate buffer solution to the pretreated sample to obtain the electroplating reaction system. Preferably, the pH value of the ammonium sulfate buffer solution is 2.1~2.3, the sulfate concentration is 1mol / L, and the volume is 10mL. The resulting electroplating system can stabilize the pH of the system during an electroplating cycle of up to 2 hours, preventing drastic pH fluctuations caused by hydrogen generation from electrodeposition and local hydrolysis, continuously maintaining the stable active ion form of uranyl ions, and avoiding the deposition of hydroxide flocculent inclusions formed by uranium hydrolysis.

[0046] S4. Constant Current Electroplating: The positive terminal of the electroplating power supply is connected to the anode of the linear electrode electroplating tank, and the negative terminal is connected to the bottom of the linear electrode electroplating tank. Electroplating is performed for 2 hours under constant current conditions, allowing uranium ion to migrate directionally and deposit on the surface of the plated sheet. Preferably, the constant current is 0.15A, the effective deposition area of ​​the plated sheet is 5mm in diameter, and the uranium content in the pretreated sample is ≤10μg.

[0047] S5. Post-treatment after plating: Add ammonia 1 minute before the end of electroplating. After electroplating, disassemble the linear electrode plating tank, rinse the plating sheet with ethanol, and air dry to obtain the uranium isotope plating source. The short-term alkaline environment passivates the surface uranium deposit layer. After power is cut off, it inhibits the back dissolution and detachment of deposited uranium in the acidic residual solution, avoiding local defects and uneven thickness of the plating layer, and ensuring the integrity of the plating layer. Ethanol is then used to quickly remove residual inorganic salts and buffer solutes from the plating surface, preventing salt crystallization and adhesion that could cause local protrusions and abnormal self-absorption of alpha rays. Finally, air drying at room temperature avoids high-temperature baking that could cause oxidation and peeling of the uranium plating layer, preserving the uniform thin-layer structure of the plating layer to the greatest extent possible. The final uranium source meets the requirements for high-resolution alpha spectroscopy testing.

[0048] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.

[0049] Example 1 This embodiment provides a linear electrode electroplating cell for preparing samples for high-resolution alpha spectrum uranium isotope measurement, the structure of which is as follows: Figure 1 As shown, a coaxial assembly design is adopted, and the overall structure is a linear coaxial electrode structure. From bottom to top, it consists of: lower base, plating sheet, plating tank, and anode, with all components assembled coaxially. The top and front views of the anode, plating tank, plating sheet, and lower base correspond to the following: Figures 2 to 9 As shown.

[0050] Regarding the materials of each structure: the bottom and the plate are made of conductive metal (stainless steel); the plating bath is made of polytetrafluoroethylene (PTFE), which has the characteristics of acid resistance, insulation and structural stability, and can be adapted to acidic electroplating systems with pH 1.5~3; the anode consists of a central Pt wire and an upper PTFE insulating cover, which can realize the dual functions of conductivity and electric field confinement.

[0051] Regarding the parameters of each structure: (1) Anode like Figure 2-3 As shown, the central conductor is a Pt wire with a diameter of 0.2 cm. The exposed section of the upper part extending out of the insulating cover has a diameter of 0.8 cm, and the effective electroplating length extending downward into the plating bath is 7.8 cm (7.0 cm + 0.8 cm). The upper PTFE insulating cover has an outer diameter of 2.8 cm and a cover thickness of 0.3 cm. The outer ring of the cover is provided with external threads, with the threaded sections having heights of 0.5 cm, 0.3 cm, and 0.4 cm respectively, and a total thread fit height of 1.6 cm. This allows it to be tightened and sealed with the threads at the top of the plating bath, achieving a secure assembly between the anode and the plating bath.

[0052] (2) Plating bath like Figure 4-5As shown, the overall dimensions are an inner diameter of 1.4cm, an outer diameter of 2.0cm, and a height of 8.0cm (0.3cm thickness at the bottom flange). The diameter of the center opening at the bottom is 0.5cm, with reserved space for the bottom center boss to pass through and support the plated sheet, achieving coaxial positioning of the plated sheet in the center of the cavity. The overall structure is a cylindrical shape with an open top and a center opening at the bottom, with threads machined on both the inner and outer walls at the top and bottom. The outer walls at both ends of the cylinder have threaded structures; the upper end is used for threaded sealing assembly with the anode insulating cap, and the lower end is used for tightening and sealing with the bottom threads, ensuring a leak-proof electroplating cavity.

[0053] (3) Bottom like Figure 8-9 As shown, the overall diameter of the bottom base is 2.6cm, and the diameter of its central bearing surface is 1.2cm, allowing for precise matching and contact with the plating sheet, ensuring assembly stability. The bottom base is integrally molded from conductive metal in a stepped T-shaped structure. The total outer diameter is 2.6cm, the diameter of the central bearing boss is 1.2cm, and the width of the lower conductive terminal is 0.6cm. The outer diameter of the central boss is exactly the same as the diameter of the plating sheet, enabling coaxial positioning and preventing eccentric misalignment during plating assembly. The height of the central bearing step is 1.2cm, the height of the inner cavity mating position is 1.4cm, and the total height of the bottom base is 3.0cm. The stepped structure provides axial positioning at the bottom of the plating tank, ensuring coaxial assembly of all components. The central raised bearing surface is specifically designed to support the plating sheet, ensuring precise coaxiality between the plating sheet and the anode Pt wire; the lower protrusion serves as the cathode terminal, ensuring reliable conduction of the negative power supply; the outer stepped positioning structure engages with the bottom of the PTFE plating tank, resulting in excellent assembly sealing and coaxiality.

[0054] (4) Plated sheet like Figure 6-7 As shown, the plating sheet, serving as the core cathode carrier for uranium isotope electrodeposition, is prepared from a metal material with strong acid resistance, excellent conductivity, and a smooth surface, enabling it to withstand long-term acidic electroplating environments with pH values ​​ranging from 1.5 to 3. The plating sheet has a diameter of 1.2 cm and a thickness of 0.2 cm, with an optimized effective plating area of ​​1.13 cm². 2 This embodiment employs a small-area cathode design and limits the effective electrodeposition area to a circular central region with a diameter of 5 mm. This effectively avoids the edge effect of traditional large-size coatings, significantly reduces the distribution differences of the uranium deposition layer, improves the uniformity of the coating from a structural perspective, reduces alpha particle self-absorption, and optimizes the alpha spectrum energy resolution.

[0055] Example 2 Based on the optimized linear electrode electroplating cell of Example 1, this example provides an electroplating method for preparing samples for high-resolution α-spectrum uranium isotope measurement, namely a high-resolution uranium isotope electroplating source preparation process. The specific operation steps are as follows: S101. First, according to Figure 1The assembly structure involves assembling the bottom, plating sheet, plating tank, and anode sequentially from bottom to top, ensuring that all components are coaxially aligned, the contact surfaces are tightly sealed, and there is no leakage or misalignment.

[0056] S102. Subsequently, the purified uranium sample (cation content less than 1‰ of uranium content, with no residual organic extraction reagents) was pretreated by evaporating the uranium sample to dryness (the sample as a whole is dry solid uranium salt powder / crystals). The sample was then dissolved by heating with 1 mL of concentrated nitric acid (mass fraction of 68%) and evaporated again to a wet salt state. This state is an intermediate transitional state in which the liquid has basically evaporated completely, leaving only a thin layer of moist salt at the bottom of the container, with no free liquid droplets, no flow, and not completely dry and cracked.

[0057] S103. Add 1 mL of 0.3 mol / L sodium sulfate solution and continue evaporating until a wet salt state is reached. This pretreatment process can completely convert uranium in the sample into soluble uranyl ions, thoroughly remove excess nitric acid and interfering components in the system, and introduce sodium sulfate as a supporting electrolyte to effectively improve the overall conductivity of the subsequent electroplating solution.

[0058] S104. After sample pretreatment, add 10 mL of prepared ammonium sulfate buffer system to the system. The pH value of the buffer system is controlled in the range of 2.1~2.3, and the sulfate concentration is 1 mol / L. This can stabilize the pH value of the electroplating system throughout the process, ensure that uranyl ions always maintain a highly active ionic form, effectively reduce the concentration polarization phenomenon during the electrodeposition process, and allow the overall electrodeposition reaction to proceed smoothly and controllably.

[0059] S105. After the solution is prepared, connect the positive electrode of the electroplating power supply to the anode of the electroplating tank and the negative electrode to the bottom of the electroplating tank. Electroplating is carried out in constant current mode for 2 hours. Under the action of a stable electric field, uranium ions in the solution migrate directionally to the surface of the cathode plate, undergo a reduction reaction and are uniformly deposited to form an ultra-thin and dense uranium source coating.

[0060] S106. One minute before the electroplating is finished, add 1 mL of ammonia (28% by mass) to the system to prevent the deposited uranium coating from dissolving after the power is turned off through passivation protection, thereby further ensuring the firmness and overall uniformity of the coating.

[0061] S107. After the electroplating process is completed, the electroplating tank structure is disassembled, and the surface of the plated sheet is thoroughly rinsed with ethanol solution to remove residual salt and trace impurities. The plated sheet is then air-dried naturally to obtain a uranium isotope electroplating source that can be directly used for high-resolution alpha spectrum measurement.

[0062] Experimental Example To determine the optimal process parameters for the electroplating bath, this experiment conducted multiple comparative tests on the two core parameters of uranium sample loading and electroplating current to determine the optimal process conditions.

[0063] Specifically, the following steps are included: S201. First, an optimization experiment on the uranium sample loading amount was conducted. Under the same electroplating process conditions as described above, with a constant current of 0.2A, electroplating sources were prepared using natural uranium samples with gradient loading amounts of 400μg, 40μg, and 4μg, respectively. Measurements were continuously taken for 2 hours, and the corresponding α-energy spectra were obtained. The experimental results are as follows: Figure 10 As shown.

[0064] Experiments show that excessively high uranium loading leads to an overly thick electroplating layer, triggering a severe alpha particle self-absorption effect, resulting in broadened energy spectrum peaks and a significant decrease in energy resolution. Therefore, the electroplating cell structure provided in this application is adapted to prepare microgram-level uranium samples, with a preferred loading amount of ≤10μg, which effectively avoids the problem of excessively thick coating, ensuring a thin and uniform coating that meets the requirements for high-resolution detection.

[0065] S202. Based on determining the optimal sample loading range, further optimization experiments of electroplating current parameters were conducted. The uranium sample loading was fixed at 4 μg, and other process conditions remained unchanged. Five sets of gradient constant current parameters (0.1 A, 0.15 A, 0.2 A, 0.3 A, and 0.4 A) were set for electroplating source preparation. The characteristic α-energy peak of 4198 keV of uranium-238, which has the highest identifiability, was selected as the resolution evaluation index. The half-width at half-maximum (WHM) and stability of the energy spectrum under different current conditions were compared. The experimental results are as follows: Figure 11 As shown in the figure. Simultaneously, the uranium-238 / uranium-234 activity ratios corresponding to each group of electroplating sources were statistically analyzed to verify the measurement accuracy. The experimental results are as follows: Figure 12 As shown. For each gradient current parameter experiment, three sets of parallel experiments were set up, three sets of parallel electroplating sources were prepared, and α-energy dispersive spectroscopy (α-ESD) measurements were completed. Figure 11 , Figure 12 The shaded areas of the mid-peak area and half-peak width data represent the standard deviations of three parallel experiments. Figure 13 The standard deviation data of activity distribution were also obtained based on the statistical analysis of three sets of parallel test results.

[0066] Experimental results show that when the electroplating current is 0.15A, the half-peak width (WHM) of the uranium-238 characteristic peak can be controlled within 10keV, exhibiting a narrow peak shape, small standard deviation, and optimal energy resolution. Simultaneously, the uranium-238 / uranium-234 activity ratio measured under this current condition approaches 1, highly consistent with the actual state of natural radioactivity equilibrium between the two nuclides in natural uranium. Electroplating sources prepared with current parameters of 0.1A, 0.2A, 0.3A, and 0.4A, compared to 0.15A, all suffer from larger WHM, peak shape distortion, and larger activity ratio deviations, failing to achieve high-resolution, high-precision detection. Therefore, the most suitable operating current for the electroplating cell and electroplating method provided in this application is 0.15A.

[0067] S203. Due to the severe edge effect in traditional linear electrode electroplating cells, uranium nuclides are deposited in a Gaussian distribution on the cathode surface, with the deposition density decreasing rapidly from the center to the edge, resulting in poor coating uniformity. Furthermore, the α energies of uranium-238, uranium-235, and uranium-234 are extremely close, easily masking the characteristic peak of uranium-235, making accurate identification and quantification impossible. This embodiment further verifies this through mechanistic experiments (such as...). Figure 13 As shown, the radial activity distribution of linear electroplating is defined by a central region. Reducing the effective deposition area can significantly reduce deposition non-uniformity and decrease the standard deviation of activity distribution.

[0068] Specifically: Starting from the radial edge of the coating and using a fixed step size of 2 mm, the effective deposition analysis area was delineated layer by layer towards the center. The radioactivity distribution of the uranium coating within each defined annular region was tested segment by segment. Each group of samples was tested in parallel three times, and the standard deviation of the activity distribution corresponding to different inward-shrinking regions was calculated. The results were plotted with the radial position as the horizontal axis and the standard deviation as the vertical axis. Figure 13 The U-shaped curve in the middle.

[0069] When the effective deposition area diameter is reduced to 7 mm, the coating uniformity is close to that of spiral electrodes and mesh electrodes; further optimization of the effective deposition area into a circular area with a diameter of 5 mm (this circular area corresponds to...) Figure 13 The central interval of the 10mm~15mm horizontal coordinate of the plated surface: The horizontal coordinate of the plated surface is the absolute position. With the center of the plated surface at 12.5mm as the center, the physical width of the 10mm~15mm interval is 15mm-10mm=5mm, that is, the diameter of the effective deposition area is 5mm. When this is the case, the standard deviation of the activity distribution can be reduced to 1.21, which can suppress the edge effect to the greatest extent, weaken the α self-absorption, and optimize the energy spectrum peak shape.

[0070] In summary, this embodiment optimizes the electroplating cell structure, limits the effective deposition area to a center diameter of 5 mm, and matches an optimal microgram-level uranium loading of ≤10 μg (4 μg in this example) with 0.15A (e.g., Figure 14 The constant current electroplating parameters are determined by... Figure 14 It can be seen that the prepared uranium electroplating source can produce high-resolution morphologies with narrow peaks and low full width at half maximum (FWHM) for the three adjacent energy groups of uranium-238, uranium-235, and uranium-234. The characteristic peak of uranium-235 is clearly distinguishable without peak overlap. The FWHM of the energy spectrum is less than 10 keV, demonstrating excellent energy resolution and verifying that this application can achieve accurate differentiation and quantitative measurement of three adjacent uranium isotopes. The α-energy spectrum of the electroplating source obtained from a large effective area (1.2 cm in diameter) electroplating cell is as follows... Figure 15 As shown, compared to Figure 14 , Figure 15The uranium-238 and uranium-234 energy spectrum peaks showed significant broadening and severe tailing, while the characteristic peaks of uranium-235 were submerged by the base of the main peaks on both sides, resulting in poor identification and making effective resolution and accurate quantification impossible. This further demonstrates that the electroplating cell and electroplating method of this application can solve the technical problems of traditional linear electroplating cells failing to identify the characteristic peaks of uranium-235 and exhibiting poor measurement accuracy. Thus, it effectively overcomes the drawbacks of traditional linear electrode electroplating cells, such as low energy resolution and poor coating uniformity. While retaining the simple structure, ease of standardization, and strong scalability of linear electroplating cells, it achieves high-resolution, high-precision alpha spectrum measurement of uranium isotopes.

[0071] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0072] Although preferred embodiments of the present 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 limited to all changes and modifications that include the preferred embodiments and fall within the scope of the embodiments of the present application.

[0073] 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.

[0074] 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 linear electrode electroplating cell for preparing samples for high-resolution alpha spectrum uranium isotope measurement, characterized in that, The device includes a bottom base, a plating sheet, a plating bath, and an anode, arranged coaxially from bottom to top. The plating sheet is a circular cathode carrier, and the effective electrodeposition area is a circular region with a diameter of 5 mm, resulting in an effective plating area of ​​1.13 cm². 2 .

2. The linear electrode electroplating bath according to claim 1, characterized in that, The bottom plate and the plated sheet are both made of conductive metal, and the plating bath is made of polytetrafluoroethylene.

3. The linear electrode electroplating bath according to claim 1, characterized in that, The anode includes a centrally located Pt conductive wire and a polytetrafluoroethylene insulating cap located above the Pt conductive wire; the diameter of the Pt conductive wire is 0.2 cm, the effective electroplating length is 7.8 cm, and the outer diameter of the polytetrafluoroethylene insulating cap is 2.8 cm.

4. The linear electrode electroplating bath according to claim 1, characterized in that, The plating bath has an inner diameter of 1.4 cm, an outer diameter of 2.0 cm, and a height of 8.0 cm; the bottom has a diameter of 2.6 cm, and the center bearing surface diameter of the bottom has a diameter of 1.2 cm.

5. The linear electrode electroplating bath according to claim 1, characterized in that, The plate has a diameter of 1.2 cm and a thickness of 0.2 cm.

6. An electroplating method for preparing samples for high-resolution alpha spectrum uranium isotope measurement, characterized in that, The electroplating bath using the linear electrode as described in any one of claims 1-5 includes the following steps: S1. Coaxial assembly: The bottom, plating sheet, plating tank and anode of the linear electrode electroplating tank are coaxially assembled from bottom to top to obtain the linear electrode electroplating tank; S2. Uranium sample pretreatment: The purified uranium sample is evaporated to dryness, dissolved by heating with concentrated nitric acid, evaporated to near dryness, and then sodium sulfate solution is added to continue evaporation until it is wet salt, thus obtaining the pretreated sample; S3. Preparation of electroplating system: Add ammonium sulfate buffer solution to the pretreated sample to obtain electroplating reaction system; S4. Constant current electroplating: Connect the positive terminal of the electroplating power supply to the anode of the linear electrode electroplating tank and the negative terminal to the bottom of the linear electrode electroplating tank. Electroplating is carried out for 2 hours under constant current conditions to allow uranyl ions to migrate in a directional manner and deposit on the surface of the plated sheet. S5. Post-solidification treatment: Add ammonia water 1 minute before the end of electroplating. After electroplating is completed, remove the linear electrode electroplating tank, rinse the plated sheet with ethanol and air dry it naturally to obtain the uranium isotope electroplating source.

7. The electroplating method according to claim 6, characterized in that, In step S2, the concentration of concentrated nitric acid is 68 wt%, and the amount used is 1 mL. The near-dry state is a state without free liquid droplets and without flow. The concentration of sodium sulfate solution is 0.3 mol / L, and the amount used is 1 mL.

8. The electroplating method according to claim 6, characterized in that, The ammonium sulfate buffer solution has a pH of 2.1-2.3, a sulfate concentration of 1 mol / L, and a volume of 10 mL.

9. The electroplating method according to claim 6, characterized in that, In step S4, the constant current is 0.15A, the effective deposition area of ​​the plate is 5mm in diameter, and the uranium content in the pretreated sample is ≤10μg.

10. The electroplating method according to claim 6, characterized in that, In step S5, the amount of ammonia added is 1 mL, and the concentration is 28wt%~29wt%.

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