Volume 66, Nº 2 (2024)

Using X-ray diffraction analysis, the structure of the crystals of Li(UO₂)₂(C₅H₆O₄)₂F⋅6H₂O (I), NaUO₂(C₅H₆O₄)F⋅4H₂O (II) and Sr(UO₂)₂(C₅H₆O₄)₂F₂⋅8H₂O (III) was studied for the first time. The uranium-containing structural units in crystals of I are 1D complexes [UO₂(C₅H₆O₄)F_0.5(H₂O)]^0.5– with the crystal chemical formula AQ⁰²M²_0.5M¹, where A = UO₂²⁺, Q⁰² = C₅H₆O₄^2–, M²= F^–, M¹ = H₂O, and in II and III, 1D complexes of the same composition and structure [UO₂(C₅H₆O₄)F]^– with the crystal chemical formula AQ⁰²M². In all compounds, the U(VI) atoms implement hexagonal-bipyramidal coordination, forming coordination polyhedra UO₂FO₅ (I) and UO₂F₂O₄ (II and III). It was found that the long-characterized uranyl fluoroglutarate {UJUBEG}, for which the composition [UO₂(С₅H₆O₄)F]⋅2H₂O was erroneously indicated, contradicting the principle of electrical neutrality, should be considered as (Н₃O)[UO₂(С₅H₆O₄)F]⋅H₂O.

Sorption of pertechnetate on pyrrhotite Fe_nS_n+1 (I) and stibnite Sb₂S₃ (II) from distilled water was evaluated. The distribution coefficients were found to be 185 and 223 cm³/g, respectively. The XPS study of the chemical state of ⁹⁹Tc absorbed on the surface of pyrrhotite and stibnite from aqueous solution of potassium pertechnetate (KTcO₄) was carried out. It was found that Tc(IV) ions are present mostly on the surface of the studied samples, their concentration was 5.7 times higher on the surface of pyrrhotite compared to that on the surface of stibnite. A 13% admixture of Tc(VII) ions on the surface of pyrrhotite was observed.

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 coefficients of raffinate purification 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 stand for 48 h with ¹³⁷Cs extraction from model alkaline HLW at a level of 99.7%.

Possibility of tritium introduction into graphene oxide (GO) by tritium thermal activation method was demonstrated. It has been established that, in order to obtain 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 provided at 77 K showed a number of advantages. Under these conditions, the specific activity of [³H]GO of 2.6 Ci/mg was reached when calculated by the mass of the initial GO (0.7 Ci/mg if purified to remove the labile tritium). Specific energy release in [³H]GO with such specific activity is 22.3 W/kg, which is enough for its application as a component of an atomic battery.

Nanodiamonds (NDs) are promising carriers of radionuclides in radiopharmaceuticals for use in nuclear medicine. In this work, we investigated the influence of the properties of ND suspensions, including the sizes of their aggregates, in aqueous solutions with different pH on their binding of medical isotopes ⁹⁰Y and ¹⁷⁷Lu and found the conditions for obtaining 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 ND surface, while the forms of cations of the studied nuclides in the solution do not affect the degree of sorption.

Using through diffusion method at room temperature, migration of RW element simulators (P, Se, Br, Mo, Cs, U) in compacted samples of clay materials of various mineral compositions was studied during porous diffusion from model solutions: underground water and leachates of phosphate waste forms having a total salt content of up to 500 mg/L. Based on the results of experiments, effective diffusion coefficients and sorption distribution coefficients of elements in barrier materials were determined. Numerical models are proposed to describe diffusion transfer of selenium, cesium and uranium depending on porosity, mineral composition of materials, and concentration of elements in pore solution. Patterns of diffusion of elements from solutions of different salt composition were revealed.