Radiochemistry最新文献

The extraction of the tricarbonate complex of uranyl [UO₂(CO₃)₃]^4– from aqueous solutions on clay powders from kaolin clays of the Kampanovskoye deposit and from bentonite clays of the 10th Khutor and Dinozavrovoe deposits, as well as their mixtures, was investigated. The studies were carried out with clay powders, both untreated and treated with water, 0.5 M Na₂CO₃ and NaNO₃ solutions, and 2 M NaOH solutions. It was shown that the [UO₂(CO₃)₃]^4– complex is not sorbed on clay materials from aqueous solutions under static conditions. The filtration of an aqueous solution of [UO₂(CO₃)₃]^4– through columns with clay mixtures was established to enable the extraction up to 87% of uranium from the amount passed through the column.

Nanodiamonds (NDs) are promising carriers of radionuclides in radiopharmaceuticals for the use in nuclear medicine. In this work, we investigated the influence of the properties of NDs suspensions, including the sizes of their aggregates, in aqueous solutions with different pH on their binding of medical isotopes ⁹⁰Y and ¹⁷⁷Lu and determination of conditions for fabricating promising conjugates for further in vivo studies. It was shown that sorption is influenced by the composition of the solution, which determines the properties of the NDs surface, while the forms of cations of the studied nuclides in the solution do not affect the sorption value.

The extractants diphenyl-N,N-dioctylcarbamoylmethylphosphine oxide and diphenyl-N,N-diisobutylcarbamoylmethylphosphine oxide for the SNF reprocessing were tested. The conditions for extraction and separation of uranium and TPE–REE were determined. A flowsheet was proposed for reprocessing SNF from high-temperature gas-cooled reactors. Upon dynamic testing, at least 99.9% of uranium and plutonium and at least 99.5% of americium and rare earth elements were separated. The TPE + REE and U + Pu fractions were recovered. The U + Pu fraction contained approximately 5% Am, while the TPE + REE fraction had less than 0.1% U and Pu.

In this work, we studied the sorption of scandium, whose isotopes ⁴⁴Sc and ⁴⁷Sc are explored for diagnostics and therapy in nuclear medicine, by aggregates of commercial (TAN, STP) and oxidized nanodiamonds (ox-STP) from aqueous solutions. The sorption capacity of the studied NDs for scandium was determined; 100 μg of NDs is found to be sufficient for the sorption of 1 GBq of ⁴⁷Sc, which is equivalent to the activity of isotopes used in therapy. It was shown that the supposed mechanism for the binding of Sc(III) to nanodiamond aggregates is chemisorption, and the chemical composition of the nanodiamond surface affects the sorption efficiency to a greater extent than the speciation of scandium in solution. The obtained data on Sc(III) sorption are correlated with the sizes of nanodiamond aggregates; it is shown that sorption under experimental conditions does not depend on the size of the aggregates. For the further development of radiopharmaceuticals based on ⁴⁷Sc, optimal carriers for this isotope—TAN and ox-STP—were suggested.

The article presents the results of studies on composition optimization, properties, and laboratory dynamic tests of extraction mixtures based on p-isononylcalix[6]arene for the alkaline HLW purification to remove ¹³⁷Cs. The distribution of ¹³⁷Cs among the products of the technological scheme is presented and the raffinate purification factor to remove ¹³⁷Cs are determined. It was revealed that, in the case of using nitric acid as a stripping solution, nitrosation of p-isononylcalix[6]arene is possible in the technological process. The composition of the resulting product was determined. To prevent nitrosation of p-isononylcalix[6]arene, formic acid was used in the stripping stage, which ensured stable operation of the extraction setup for 48 h while ¹³⁷Cs extraction from model alkaline HLW was at a level of 99.7%.

The possibility of tritium introduction into graphene oxide (GO) by tritium thermal activation method was demonstrated. It was established that, in order to produce the highest possible specific radioactivity, thin films of GO with a thickness of 5.6 mg/m² must be treated with tritium atoms. The experiment conducted at 77 K showed a number of advantages. GO was processed with tritium atoms, the resulting specific activity of [³H]GO reached 2.6 Ci/mg in term of the weight of the initial GO (0.7 Ci/mg after removal of the labile tritium). Specific energy release of [³H]GO with this specific activity is 22.3 W/kg, which is quite sufficient for its application as a component of a nuclear battery.

The thermal stability of dibenzo-21-crown-7 and of MN-200 organic matrix based on styrene–divinylbenzene in inert and oxidizing atmosphere at temperatures of up to 600°С was studied. Solid extractants (SEs) were prepared from these components. These SEs are stable up to 300°С in inert atmosphere and up to 180–250°С in oxidizing atmosphere, depending on the presence of an additional diluent, fluorinated alcohol, in the SE. At higher temperatures, the SEs undergo exothermic processes accompanied by the formation of such major gaseous products as toluene, styrene, benzaldehyde, 1-ethyl-4-methylbenzene, and 1,3-dioxolane. Their yield depends on the type of the gaseous atmosphere used.

Speciation of uranium in trace concentrations in water of complex chemical composition was studied using ultrafiltration and sorption methods in a wide range of solution acidity. As shown by the experiments and computations, uranium in trace concentrations in aqueous solutions identical to wastewater from the facilities occurs at pH 1–3 in the truly dissolved state in the form of UO₂²⁺ and UO₂OH⁺ ions. At pH ≥ 4, uranium(VI) mainly occurs in the pseudocolloidal form due to sorption on hydroxides of iron, aluminum, or other impurity elements. The decrease in the fraction of uranium colloids at pH ≥ 7 is due to the formation of stable, negatively charged uranyl carbonate complexes in the solution.

The natural radioactivity in soil samples collected from the Khasa River, which flows in the Kirkuk city of Iraq, was studied using a high-purity germanium (HPGe) detector and a spectroscopy system. The activity concentrations (Bq kg⁻¹) of ²¹⁴Pb, ²²⁶Ra, ²¹²Pb, ²²⁸Ac, and ⁴⁰K varied from 10.1 ± 0.6 to 27.5 ± 3.2, from 23.4 ± 2.8 to 44.1 ± 6.1, from 13.2 ± 0.7 to 26.4 ± 1.8, from 12.5 ± 0.9 to 28.1 ± 4.3, and from 206.5 ± 12.8 to 332.2 ± 7.2, respectively. The results have been compared to the average worldwide values. The hazard indices have also been calculated. The average of radium equivalent activity (Ra_eq) was 81.2 Bq kg⁻¹; the absorbed gamma dose rate (D) was 42.8 nGy h⁻¹; the annual effective dose rates (AEDE) outdoor and indoor were 0.05 and 0.2 mSv year⁻¹, respectively; the external hazard (H_ex) was 0.2; the internal hazard (H_in) was 0.3; the gamma radiation representative level index (I_γ) was 0.5. Our results for some sites were found to be higher than the worldwide values.

The lognormal statistical distribution was used to present the reliable integrated data on the content of various physicochemical forms of tritium in air, natural water, and components of aquatic ecosystems at nuclear facility sites. Statistics of lognormal distributions took into account the left truncation, which reflects the effect of finite sensitivity of measurements. The statistics of lognormal distributions were used to obtain estimates for ecosystems of NPP sites at limited sets of data. Specific activities were estimated for various forms of tritium such as HTO (free water), TFWT (tissue free water tritium), and OBT (organically bound tritium). The measurement results show that the specific activity of tritium in the body in bound forms was, as a rule, higher than its specific activity in free water in the ambient environment. Equilibrium concentration ratios (CRs) (partition coefficients of hydrogen) ranged from 1 to about 20. The results obtained by the Radium Institute research team agree with those obtained by the researchers from Canada and France for the specific activity of tritium in different chemical forms in environmental samples.