63 results about "Uranyl" patented technology

A method for predicting in-situ leaching effects of sandstone-type uranium mining deposits after blasting is provided, which comprises: based on a finite element analysis platform, establishing an HJC rock-blasting constitutive model, and carrying out a blasting numerical simulation; calibrating a cloud map of blasting crack damage by using a Kriging interpolation algorithm; establishing a COMSOL multiphysics model; establishing a coupling interface between the COMSOL multiphysics model and PHREEQC based on MATLAB, and optimizing a cycle duration and a time step; performing a geochemical reaction calculation and saving results, running COMSOL files, and inputting the results of geochemical reaction calculation into PHREEQC to obtain a dynamic cyclic iterative simulation; dynamically correcting migration coefficients of uranyl complexes by integrating an LSTM neural network, and stopping the cycle to output multi-scale dynamic simulation results of migration of uranium.

The invention discloses a method for efficiently separating uranyl ions based on a titanium-based metal organic framework material, the titanium-based metal organic framework material is MOF-902, and the adsorption separation of the uranyl ions can be realized by adding the titanium-based metal organic framework material into a liquid containing the uranyl ions. The invention develops a novel adsorbent for uranyl ion separation, which can realize rapid selective separation of uranyl ions.

The invention discloses an amidoximation hydrotalcite material as well as a preparation method and application thereof, and the method comprises the following steps: grafting and modifying an amino group on hydrotalcite to obtain an amination modified hydrotalcite material; grafting and modifying an aldehyde group on the amination modified hydrotalcite material to obtain an aldehyde modified hydrotalcite material; carrying out condensation reaction on the hydroformylation modified hydrotalcite material and a reagent containing amino and cyano groups at the same time to obtain a cyanylation modified hydrotalcite material; and carrying out amidoximation reaction on the cyanation modified hydrotalcite material and an oximation reagent to obtain the cyanation modified hydrotalcite material. The amidoximation hydrotalcite powder material prepared by the preparation method disclosed by the invention can realize high-specificity recognition and efficient adsorption on uranyl ions.

The invention discloses a post-blasting sandstone type uranium mine in-situ leaching mining effect prediction method, and relates to the field of sandstone type uranium mine in-situ leaching mining effect numerical simulation, and the method comprises the steps: building an HJC rock blasting constitutive model based on a finite element analysis platform, and carrying out the blasting numerical simulation; calibrating the blasting crack damage nephogram through a Kriging interpolation algorithm; a COMSOL multi-physical field model is constructed; constructing a coupling interface of the COMSOL multi-physical field model and the PHREEQC based on MATLAB, and optimizing the cycle time and the time step length; performing geochemical reaction calculation and storage, running a COMSOL file at the same time, and inputting a geochemical reaction calculation result into PHREEQC to obtain dynamic loop iteration simulation; and through integration of the LSTM neural network, dynamically correcting the migration coefficient of the uranyl complex, carrying out circulation termination, and outputting a uranium migration multi-scale dynamic simulation result. According to the method, multi-scale dynamic simulation of uranium migration in the leaching agent injection process is realized, and the uranium migration prediction precision is improved.

The invention discloses a method for electrifying and extracting a uranium element from sandstone uranium ore, which comprises the following steps: adjusting the pH value of an activation environment to be less than or equal to 4 by using an activation leaching agent, and converting the uranium element in the sandstone uranium ore into uranyl with positive charges and a complex thereof; wherein the activation leaching agent is a mixed solution of FeCl3 and chlorine-containing inorganic acid; the sandstone uranium ore is activated and then introduced into a direct-current electric field, direct current with the voltage gradient of 1-4 V / cm is applied, the uranium element moves towards a cathode directionally under the action of the electric field, and uranium-rich leachate is collected at the cathode. According to the method, the uranium element in the sandstone uranium ore is controlled to only form positive charge ions and complexes, the use amount of the leaching agent is reduced, the leaching rate of the uranium element is increased, and the collection time of the uranium element is shortened, so that the purpose of extracting the uranium element in the sandstone uranium ore more efficiently and greenly is achieved.

The invention discloses preparation of a cyano-mediated 0D / 2D C3N5 / C3N4 heterojunction and application of the cyano-mediated 0D / 2D C3N5 / C3N4 heterojunction in photocatalytic uranyl reduction extraction. The invention provides the preparation method of the photocatalytic material which is simple in synthesis, high in U (VI) reduction speed and high in reduction efficiency. The preparation method comprises the following steps: compounding a 2D photocatalyst carbon nitride (g-C3N4) with 0D carbon nitride quantum dots (CNQDs) to prepare a g-C3N4 / CNQDs heterojunction mediated by a cyano group; the material has high photocatalytic activity and can be used as a catalyst for reducing U (VI), and the reduction rate of the material is 80.47% and is far higher than the reduction rate of g-C3N4 (39.42%) and CNQDs (1.61%).

The present invention provides a method for fixing uranium and its application in a solid fuel cell, wherein UO2(NO3)2·6H2O, Ce(NO3)3·6H2O, Y(NO3)3·6H2O and a barium salt soluble in nitric acid and easily decomposed at high temperature are dissolved in deionized water, and a novel BaCe is prepared under the action of a complexing agent. 0.8‑x U x Y 0.2 O3 (BCUY) material, which can be used in solid fuel cells as a new proton conductor electrolyte material. The raw materials of uranyl nitrate used are prepared from discarded uranium salts, uranium minerals or secondary uranium minerals, which realizes the recycling of discarded uranium resources and provides a new way for the practical application of uranium in solid fuel cells. The present invention can not only immobilize uranium well, reduce the migration of uranium, and reduce its harm to the environment; but also the new BCUY material has good chemical stability and high application value, and can be used in solid fuel cells to extend the service life of the battery.

The invention discloses a method for quantitatively detecting uranyl ions by adopting a silicon-based carbon dot material and application of the method, and belongs to the field of nano composite materials and radionuclide detection. Mixing the silicon-based carbon dot composite material with an acid solution containing uranyl ions, carrying out ultrasonic treatment, detecting the fluorescence intensity of the mixed solution by adopting a fluorescence spectrum, and quantitatively analyzing the uranyl ion concentration according to the uranyl ion concentration and a fluorescence intensity curve. The silicon-based carbon dot composite material is a silicon-based carbon dot material of which the surface is modified by functional groups; the functional groups comprise hydroxyl, carboxyl and amino. The method can generate stable fluorescence response change when acting with uranyl ions, accurate quantitative analysis of uranyl ion concentration can be realized, the silicon-based carbon dot composite material has high uranyl ion detection response speed by means of the synergistic effect of the nanoscale effect and the surface functional group, and detection can be completed in a short time.

The present invention relates to a rapid detection biosensor for uranyl ions, a detection kit and a detection method. The rapid detection biosensor for uranyl ions uses Y-shaped rolling circle-mediated triple Walker as a signal amplifier to achieve signal amplification for detecting UO2 2+ ; The Y-shaped rolling circle-mediated triple Walker includes an E1 / E2 / E3 / Assist complex, a UO2 2+ -dependent DNAzyme substrate strand, colloidal gold, and a buffer solution. The E1 / E2 / E3 / Assist complex includes a UO2 2+ -dependent DNAzyme enzyme strand and an auxiliary strand Assist. The UO2 2+ -dependent DNAzyme substrate strand is co-modified with a fluorophore, a fluorescence quenching group, and an rA base. The E1 / E2 / E3 / Assist complex is co-modified with a fluorescence quenching group and an A base. The kit and method have high sensitivity and high specificity.

The application belongs to the technical field of ion detection, and particularly relates to a preparation method of a rapid detection uranyl ion ratio type fluorescent probe, comprising the following steps: dissolving rhodamine B and phosphorus oxychloride in 1,2-dichloroethane to obtain product 1; dissolving the product 1 in acetonitrile, adding 2-aminobenzimidazole and triethylamine, and stirring under heating; after the reaction is completed, column chromatography purification is carried out, and vacuum drying is carried out to obtain the target product fluorescent probe RBN; and the fluorescent probe RBN is dissolved in DMSO to prepare a mother liquor. The fluorescent probe has the advantages of rapid response to uranyl ions, simple synthesis route, simple detection equipment and method, and the like, and can be used for qualitative and quantitative detection of uranyl ions in an environment and a biological system.

A large-flux uranyl nitrate solution backwashing filtering device comprises a filtering shell and a base, and the filtering shell comprises a lower end shell, a middle shell and an upper end shell; the barrel-shaped filter element is located in the filter shell, a hollow backwashing rotating shaft is arranged in the center of the interior of the barrel-shaped filter element, and the hollow backwashing rotating shaft penetrates through the barrel-shaped filter element upper end cover and the upper end shell and extends to the position above the upper end shell; a large-flux uranyl nitrate solution backwashing filtering method comprises the following steps that S1, a uranyl nitrate solution is guided into a filtering shell through a material inlet, and filtered materials are guided out from a liquid guiding-out pipe; s2, judging whether the barrel-shaped filter element is blocked or not through a differential pressure gauge, and backwashing the barrel-shaped filter element by connecting an inlet joint with an outlet of an external cleaning infusion pump; s3, the cleaning liquid obtained after back flushing of the barrel-shaped filter element is guided out from a waste outlet and a liquid guide-out pipe.

This invention discloses a purification method for producing molybdenum-99 in a reactor using uranyl nitrate solution as nuclear fuel, relating to the field of radioisotope production technology. The method involves first adding an oxidant to the crude molybdenum-99 product solution produced by the solution reactor, oxidizing the crude molybdenum-99 product to MoO4. 2‑ The solution is then evaporated to dryness; a digestion solution is added to the evaporation residue to dissolve the impurities; a dissolving solution is added to the digested solid to dissolve the solid, which is then evaporated to dryness; finally, an alkaline solution is added to the evaporated solid to dissolve it, yielding a molybdenum-99 product solution that meets pharmacopoeia requirements. Compared to traditional methods for purifying molybdenum, this invention does not introduce new impurities, has a low heating temperature, low energy loss, is easy to operate in a hot chamber, and has a high impurity removal rate.

The present invention discloses a method for preparing stable copper nanoclusters (CuNCs) based on glutathione (GSH) as a ligand. The method includes: first, preparing an aqueous solution of copper chloride, then adding a glutathione solution to the above solution in a certain proportion, fully stirring for five minutes at room temperature to form a white turbid solution, dropping a certain amount of sodium hydroxide solution until the solution becomes clear, then vigorously stirring at room temperature, transferring the solution into a dialysis bag for further dialysis, and then filtering through a microporous membrane. The copper nanoclusters prepared by the present invention have high sensitivity, good selectivity, strong anti-interference ability, a low detection limit for uranyl ions (the detection limit is 6.7 nM), and are used for real-time detection in real water samples including lake water, seawater, and pure water to evaluate the applicability of the copper cluster probe in the environment, having practical application value.

This invention discloses a biosensor for detecting uranyl ions using a test strip, comprising a reaction system and a test strip. The reaction system includes a DNAzyme substrate chain and a DNAzyme enzyme chain. The test strip includes a substrate and a sample pad, a coupling pad, a nitrocellulose membrane, and an absorbent pad sequentially overlapped on the substrate. A gold nanoparticle-DNA probe I complex is immobilized on the coupling pad. A test line and a control line are provided on the nitrocellulose membrane. An SA-biotin-DNA probe II is immobilized on the test line, and an SA-biotin-DNA probe III is immobilized on the control line. Compared with existing technologies, this biosensor integrates a DNase-induced cleavage reaction with gold nanoparticle-mediated colorimetric detection technology, achieving high sensitivity and high specificity detection of uranyl ions. Furthermore, the detection process is simple and rapid, providing a solution for detecting UO2 in environmental and biological samples. 2+ This provides important technical support for on-site monitoring.

The invention relates to a biosensor, a kit and a detection method for rapidly and highly sensitively detecting uranyl ions. According to the biosensor, a four-leaf clover-shaped rolling loop mediated quadruple Walker is adopted as a signal amplifier to amplify a signal to detect UO2 < 2 + >; the four-leaf clover-shaped rolling loop mediated quadruple Walker comprises an L1 / L2 / L3 / L4 / Asist compound, a UO2 < 2 + > dependent DNAzyme substrate chain, a streptavidin modified magnetic bead and a buffer solution. In the presence of UO2 < 2 + >, the activated Walker can circularly cut a fluorescently-labeled substrate chain to generate an amplified fluorescence signal, so that high-sensitivity and high-specificity detection of UO2 < 2 + > is realized.

The present application belongs to the technical field of environmental detection, and particularly relates to a Turn-On type fluorescent polymer, a synthesis method thereof and application of the fluorescent polymer in detecting uranyl ions. The present application ingeniously uses the structural characteristics of tetraphenyl ethylene tetracarboxaldehyde to synthesize a fluorescent polymer TPE-COPs having a fluorescence enhancement response to uranyl ions at normal temperature. The fluorescent polymer is a "Turn-On" type fluorescent polymer, has advantages of high sensitivity, high selectivity and rapid response in detecting uranyl ions, can simultaneously improve the sensitivity and anti-interference ability, realizes all-round consideration of the detection limit, the detection range and the selectivity, and shows great potential and value in biomedical research and application. Meanwhile, the fluorescent polymer TPE-COPs of the present application can be completed at room temperature, has a simple process, does not need harsh environments such as high temperature, high pressure and oxygen-free, and is more suitable for industrial scale production application.

The invention discloses preparation of an ultrafast uranyl response AgNWs (at) CZS (at) CdZn-ZIF8 flexible photoelectrode and uranyl detection application of the ultrafast uranyl response AgNWs (at) CZS (at) CdZn-ZIF8 flexible photoelectrode. The method comprises the steps that oily carbon cloth is subjected to plasma cleaning and then soaked with a mixed solution of ceric ammonium nitrate, water and nitric acid; then soaking in a mixed solution of acrylic acid, acrylonitrile and DMF (Dimethyl Formamide), and heating in a water bath; after being taken out, the polymer coating carbon cloth is added into a mixed solution of hydroxylamine hydrochloride, isopropanol and sodium hydroxide, water bath heating is conducted again, and the polymer coating carbon cloth is obtained. The preparation method comprises the following steps: magnetically stirring and heating PVP-containing propylene glycol in a water bath, quickly adding NaCl, continuously stirring, adding an AgNO3 solution, and magnetically stirring and heating; and collecting the precipitate, and washing with acetone and ethanol respectively to obtain gray AgNWs. The preparation method comprises the following steps: adding 2-methylimidazole and AgNWs into an organic solvent solution containing organic amine to obtain an AgNWs composite solution; wherein in the aqueous solution of the organic amine or the organic solvent solution, the concentration of the organic amine is 8-9%; and mixing organic solvents containing cadmium salt and zinc salt to obtain the zinc-cadmium composite solution. The AgNWs composite solution and the zinc-cadmium composite solution are respectively heated and coated on polymer coating carbon cloth, then the polymer coating carbon cloth is put into an organic solvent containing thiourea, after the mixture is heated in a water bath, vacuum drying is carried out, and the AgNWs (at) CZS (at) CdZn-ZIF8 flexible photoelectrode is obtained. According to the invention, the polymer coating carbon cloth is used as a substrate to prepare the AgNWs (at) CZS (at) CdZn-ZIF8 flexible photoelectrode, and the flexible photoelectrode has ultrafast uranyl response capability.

The invention relates to the technical field of metal frame materials, in particular to an amidoxime-modified and titanium-doped MOFs (Metal-Organic Frameworks) material as well as a preparation method and application thereof. Comprising the following steps: 1, synthesizing MIL-101 (Cr) by using terephthalic acid and chromium nitrate nonahydrate as raw materials and adopting a solvothermal method; 2, MIL-101 (Cr) and butyl titanate are used as raw materials and subjected to a replacement reaction after being oscillated and mixed, and a Ti-doped MIL-101 material is obtained; 3, the Ti-doped MIL-101 material and aminoacetonitrile are used as raw materials, and a Ti-MIL-101 material functionalized by the aminoacetonitrile is prepared; the preparation method comprises the following steps: preparing a hydroxylamine hydrochloride solution, dissolving an aminoacetonitrile functionalized Ti-MIL-101 material in the hydroxylamine hydrochloride solution, centrifuging, and drying to obtain the AO-Ti-MIL-101. According to the prepared AO-Ti-MIL-101, the adsorption efficiency of the AO-Ti-MIL-101 material on uranyl ions is as high as 97.72% under the condition of low concentration (100 [mu] g.L <-1 >); and in a high-concentration (100mg. L <-1 >) environment, the removal rate of uranyl ions is 87.85%. The adsorption capacity can reach the level of 185.35 mg.g <-1 >, and the theoretical maximum adsorption capacity is 404.67 mg.L <-1 >.

The invention belongs to the technical field of ion detection and dye degradation, and particularly relates to a cadmium complex as well as a preparation method and application thereof. The chemical formula of the cadmium complex is [Cd (MIPMO) (NPTH) (H2O)], MIPMO is 4, 4 '-bis (2-methylimidazole-1-yl) benzophenone, and H2NPTH is 3-nitrophthalic acid. The cadmium complex disclosed by the invention has a fluorescent recognition function on uranyl ions and permanganate ions, can be used for detecting trace uranyl ions and permanganate ions in an aqueous solution, and has quenching constants of 6.26 * 10 < 3 > and 3.32 * 10 < 3 > respectively. The cadmium complex disclosed by the invention can effectively degrade methylene blue and methyl orange dyes.

A method for separating molybdenum-99 and iodine-131 from a nuclear reactor fuel solution that uses a uranyl nitrate aqueous solution as fuel, comprising the following steps: S1, causing a fuel solution containing fission products to flow through a pretreated extraction column and, after elution and desorption, obtaining a 99Mo and 131I solution, the fuel solution containing the fission products being a uranyl nitrate solution obtained at the end of the operation of a nuclear reactor; S2, causing the 99M and 131I solution obtained in step S1 to flow through a separation column for 99Mo adsorption, a filler material of the separation column being ST-150 resin to which α-benzoin oxime is adsorbed; and S3, an adsorption effluent of the separation column being a 131I crude product, and successively cleaning and desorbing the separation column, so as to obtain a 99Mo crude product.

The present invention relates to the field of uranyl ion detection technology, and in particular to a near-infrared fluorescent probe based on xanthene and its preparation method and application. The present invention provides a novel near-infrared fluorescent probe based on xanthene. The probe is combined with UO2 2+ The fluorescence is enhanced after binding and can be successfully applied to UO2 in living mice 2+ Biological imaging and understanding UO2 2+ distribution and toxicity in biological systems.

The invention discloses a high-activity uranium trioxide production method and equipment for treating large-flux uranyl nitrate, and the method comprises the following steps: introducing fuel gas into a combustion chamber through a gas supply system, and enabling the fuel gas to be subjected to combustion reaction to generate high-temperature gas; high-temperature gas is introduced into the reaction chamber, a uranyl nitrate solution is conveyed into the reaction chamber, the uranyl nitrate solution makes contact with the high-temperature gas, then a thermal decomposition reaction is conducted, and powder mixed gas is obtained; powder mixed gas in the reaction chamber is conveyed to a powder receiving hopper through an L discharging valve and filtered through a filtering device, then the gas is introduced into a tail gas purification system to recycle nitric acid, nitric oxide in tail gas is converted into nitrogen and then discharged, the powder is led out to a collecting device after being settled, and a uranium trioxide finished product is obtained. The uranium trioxide product prepared by the method is large in specific surface area, high in activity, large in treatment flux, high in tail gas treatment efficiency and good in effect, and can solve the problems that high-flux uranyl nitrate cannot be treated and nitric oxide severely exceeds the standard in the prior art.

The invention discloses an irradiation modification method of precious metal nano-enzyme and application of the irradiation modification method, and belongs to the technical field of nano-enzyme modification.The method comprises the steps that the precious metal nano-enzyme is prepared and dried; irradiating the dried noble metal nano-enzyme, and controllably introducing vacancy, dislocation, grain boundary or amorphous region defects by selecting irradiation source types and regulating irradiation energy and dose to obtain irradiation modified noble metal nano-enzyme; the method is different from a traditional nano-enzyme chemical modification method, the defects of the nano-enzyme are regulated by adopting physical irradiation, impurities are prevented from being introduced into a chemical reagent, the defect density is controllable, and the peroxidase-like activity of the obtained irradiation modified noble metal nano-enzyme is remarkably enhanced compared with that of an unirradiated sample; good application prospects are shown in the fields of uranyl ion detection and the like.

The application discloses a kind of amidoxime hydroslate-antimony alkene composite material and its preparation method and application, by first on the surface of hydroslate modification amino group, then using amino group graft modification cyano group, the cyano group is converted into hydroxamic acid group by amidoxime reaction, obtain amidoxime hydroslate;The amidoxime hydroslate dispersion is formed by dispersion, then with antimony alkene dispersion liquid is mixed and is mutually stacked to form two-dimensional layered composite material, by centrifugation, dry obtain.This composite material can effectively inhibit the agglomeration of antimony alkene and hydroslate nanosheet, and can increase the active site of material and uranium ion combination, be applied to the electrochemical detection of uranium ion, with high conductivity, high stability of antimony alkene, and high specificity adsorption of hydroslate.

The invention provides a method for preparing a UO2 fuel pellet with a high fuel consumption structure, which comprises the following steps: (1) preparing a UO2 solution: weighing uranyl and hydrazine hydrate, and adding into water to form a uniform solution; (2) preparing UO2 powder: heating the solution to obtain a uranium dioxide suspension, then washing the suspension with ethanol, centrifuging, and naturally airing the precipitate to obtain the UO2 powder; and (3) core block preparation: mixing the UO2 powder and a pore forming agent, and molding through a hot pressing process.

The invention belongs to the field of analysis of radioactive elements, and discloses preparation and application of a porphyrin-based metal organic complex fluorescent probe Ni-TCPP. The method comprises the following steps: dissolving a solid mixture of NiCl3. 6H2O and PVP in a centrifugal tube containing a DMF / ethanol mixed solution; then slowly adding TCPP into the centrifugal tube, and carrying out ultrasonic treatment; finally, the solution is transferred into a PTFE lining, and then the PTFE lining is sealed in a stainless steel autoclave to be treated; and after the reaction is completed, centrifuging, cooling to room temperature, washing, and drying overnight to obtain the Ni-TCPP. Compared with other MOF light-emitting sensing materials, the MOF light-emitting sensing material disclosed by the invention has the advantages that the long-wavelength fluorescence characteristic similar to that of a rare earth doped material can be maintained, and meanwhile, the MOF light-emitting sensing material responds to ultra-low-concentration uranyl ions (16.59 nM) and has higher specificity, higher sensitivity and huge practical application value.

The invention belongs to the technical field of environment detection, and particularly relates to a Turn-On type fluorescent polymer, a synthesis method thereof and application of the Turn-On type fluorescent polymer in uranyl ion detection. The structural characteristics of tetraphenylethylene tetraaldehyde are ingeniously utilized, the fluorescent polymer TPE-COPs with fluorescence enhancement response to uranyl ions is synthesized at normal temperature, and the fluorescent polymer is a Turn-On type fluorescent polymer and has the advantages of high sensitivity, high selectivity, quick response and the like in the aspect of uranyl ion detection. The sensitivity and the anti-interference capability can be improved at the same time, the detection limit, the detection range and the selectivity are comprehensively considered, and huge potential and value are shown in biomedical research and application. Meanwhile, the fluorescent polymer TPE-COPs can be prepared at room temperature, the process is simple, high-temperature, high-pressure, oxygen-free and other harsh environments are not needed, and the fluorescent polymer TPE-COPs is more suitable for industrial large-scale production and application.

The invention discloses an acid-resistant loose nanofiltration membrane as well as a preparation method and application thereof, and belongs to the technical field of water treatment membranes. According to the preparation method, 3, 5-diaminobenzoic acid (DABA) is taken as a water-phase monomer and is subjected to interfacial polymerization with 1, 3, 5-trimesoyl chloride (TMC) on the surface of an ultrafiltration bottom membrane, and the acid-resistant loose nanofiltration membrane is obtained. Carboxyl contained in DABA can reduce the reaction activity of amino and acyl chloride groups in TMC and provide certain steric hindrance, and formation of a loose polyamide network structure is facilitated; meanwhile, the acid resistance of the nanofiltration membrane is enhanced by the contained whole aromatic rings. The prepared loose nanofiltration membrane can efficiently and selectively separate uranyl ions / coexisting inorganic ions under acidic and alkaline conditions, and shows excellent anti-pollution performance. The preparation method provided by the invention is simple in process and easy to operate, and the prepared acid-resistant loose nanofiltration membrane has potential application value for treating actual radioactive spent fuel post-treatment wastewater.

The invention belongs to the technical field of nuclear fuel development, and particularly relates to a preparation method of a large-grain UO2 fuel pellet. The preparation method comprises the following steps: (1) uniformly mixing a grain growth substance and an acid-deficient uranyl nitrate solution, adding saturated ammonium carbonate or introducing reaction gas for precipitation reaction to generate an AUC precipitate; the reaction gas is a mixture of NH3 and CO2; (2) filtering the AUC precipitate to obtain a filter cake, and washing, filtering, drying and calcining to obtain powder; (3) granulating the powder, and forming to obtain a green fuel pellet; and (4) sintering the green fuel pellet to obtain the large-grain UO2 fuel pellet. The average grain size of the prepared large-grain UO2 fuel pellet is larger than or equal to 40 micrometers, and the large-grain UO2 fuel pellet has the high melting point, good water corrosion performance and irradiation stability of traditional UO2 fuel and further has the low fission gas release rate and the high heat conductivity.

The present invention discloses a method for extracting and separating uranium from sandstone uranium ore in one step by applying electricity. The method comprises: using an activation leaching agent to adjust the pH of the activation environment to ≤3, thereby converting the uranium in the sandstone uranium ore into positively charged uranyl and its complex; applying a DC electric field with a voltage gradient of 0.1 to 2 V / cm between anode and cathode electrodes, causing the uranium to migrate toward the cathode chamber under the action of the electric field and selectively reduce on the cathode, where it is reduced to a low-valent, insoluble uranium-containing substance that precipitates on the cathode surface by gaining electrons. The present invention uses activation leaching to form only positively charged uranium ions and their complexes, and electrophysical effects such as electromigration and electroosmosis cause the uranium to move toward the cathode in a directional manner, thereby achieving the extraction of uranium from the sandstone uranium ore; at the same time, through electrochemical effects such as reduction caused by gaining electrons on the surface of the cathode conductive plastic electrode, the soluble uranium is reduced and fixed on the surface of the cathode conductive plastic electrode, thereby achieving the one-step separation and purification of the uranium.