Vol 59, No 2 (2017)

Uranyl malonate monohydrate [UO₂(mal)(H₂O)], where mal^2– is malonate ion, was synthesized and studied by single crystal X-ray diffraction. The main structural units are electrically neutral [UO₂(mal)(H₂O)] layers belonging to crystal-chemical group AQ²¹М¹ (A = UO₂²⁺, Q²¹ = mal^2–, M¹ = H₂O) of uranyl complexes. Specific features of the packing of the uranium-containing complexes are discussed on the basis of Voronoi–Dirichlet tessellation. The structural differences between the monohydrate synthesized and the known uranyl malonate trihydrate are considered.

The structure and properties of the needle-like phase of crystalline compounds of the general composition Co(NH₃)₆NpO₅·nH₂O, precipitated from alkaline Np(VII) solutions with [Co(NH₃)₆]³⁺ ions, were studied. The needle-like phase under the layer of the mother liquor is unstable and transforms into a platelike phase identified as [Co(NH₃)₆][NpO₄(OH)₂]·2H₂O (1). In the structure of 1, all the Np atoms are equivalent, but the Mössbauer spectrum recorded at a liquid helium temperature revealed the presence of two nonequivalent Np atoms. The isolated needle-like phase, according to single crystal X-ray diffraction data, at 100 K has the composition [Co(NH₃)₆]₃[NpO₄(OH)₂]₃·4H₂O (2). In the structure of 2, there are two crystallographically independent Np(VII) atoms. The Np(1) atom is in the inversion center, and the Np(2) atom occupies a general position. The structure of 1 was additionally refined, and the structures of 1 and 2 were compared. Both compounds have a similar structure, but the structure of 2 is less ordered, and the formation of both structures is influenced by hydrogen bonds involving water molecules and [NpO₄(OH)₂]^3– ions. In the structure of 1, hydrogen bonds of type O–H···O form a three-dimensional network. In the structure of 2, the O–H···O hydrogen bonds are weaker and form a two-dimensional network. In the structure of 1, there are two water molecules per [NpO₄(OH)₂]^3– anion, and in the structure of 2, 4/3 water molecules. Needle-like phase 2 in contact with solutions transforms into stable platelike phase 1 with dense packing and a three-dimensional system of hydrogen bonds. The size of needle-like crystals increases, and the rate of their transformation into platelike crystals decreases with increasing alkali concentration and decreasing temperature. The influence of the experiment conditions on the interaction of Np(VII) with [Co(NH₃)₆]³⁺ ions in weakly alkaline (0.05–0.15 M) solutions was also studied. The precipitates formed are characterized by the ratio [NpO₄(OH)₂]^3–: [Co(NH₃)₆]³⁺ = 2: 1 and are identified as the known compound LiCo(NH₃)₆Np₂O₈(OH)₂·2H₂O.

The effect of a series of halogenated diluents [bis(octafluoroamyloxy)methane, phenyl trifluoromethyl sulfone, methyl dodecafluoroheptyl ether, m-nitrobenzotrifluoride, hexachlorobutadiene, CHCl₃, CCl₄] on the extraction of spent nuclear fuel solution components [HNO₃, U(VI), An(IV), Zr, and Tc] into 30% TBP was studied and mathematically described using improved A.M. Rozen’s model. Comparison with the TBP–paraffins extraction system was made.

Sorption of ¹³⁷Cs from seawater onto a selective cation exchanger based on resorcinol–formaldehyde resin was studied. The maximal distribution coefficient of ¹³⁷Cs at the ratio S: L = 1: 1000 is (4.1–4.5) × 10³ cm³ g^–1. The sorption-selective characteristics of the resin are negatively affected by alkaline earth meal ions. In the dynamic regime, the operation life of the resorcinol–formaldehyde resin exceeds 700 bed volumes with more than 95% efficiency of cesium sorption. More than 95% of ¹³⁷Cs is eluted with a 1–3 M HNO₃ solution. The eluate volume does not exceed 10 bed volumes.

A radiometric method based on redox substoichiometry was applied to accurate and precise determination of manganese. The proposed technique is based on the substoichiometric oxidation of bivalent manganese to permanganate ions with potassium periodate, followed by isolation of the oxidized species by the extraction with tri-n-octylamine in chloroform. The method was successfully applied to the estimation of manganese content of various certified ores and alloys.

A method was developed for immobilization of prepared human chorionic gonadotropin (β-hCG) antisera on fresh plastic beads through a covalent immune bridge. Such covalent immune-coated antisera on plastic beads were used in the development of a noncentrifugation radioimmunoassay. ¹²⁵I-β-hCG was prepared using different oxidizing agents. The solid-phase RIA system developed was found to well compete with the conventional method.

Microbiological oxidation of liquid organic radioactive waste (ORW), spent vacuum and transformer oils, is described. The physicochemical properties of oils and their structural-group composition before and after using in the process cycle were studied. Changes in the structural-group composition and physicochemical parameters of oils upon microbiological treatment were determined. The distribution of radionuclides between the organic and aqueous phases upon microbiological treatment was studied by the example of model ORW containing ¹³⁷Cs, ⁹⁰Sr, ²³⁸Pu, and ²⁴¹Am. The compatibility of oils subjected to microbiological treatment with the cement compound intended for ORW disposal was evaluated. The biological step of the radioactive oil processing leads to a decrease in the weight and volume of the organic radioactive waste and increases its amount that can be incorporated into the cement compound (to 30 vol %) without deterioration of the strength characteristics of the cement.

Thirty-one tobacco samples were evaluated for the activity concentrations of radon and radium using solid-state nuclear track detectors (CR-39). The detectors were exposed for a period of 150 days to different types of cigarette tobacco. The highest values of 364 Bq m^–3 for radon and 31.4 Bq kg^–1 for radium were obtained for MIA2 sample, and the lowest values of 20.2 Bq m^–3 for radon and 1.74 Bq kg^–1 for radium, for SUM sample. According to the estimate, this range of radon levels corresponds to the lung cancer incidence in the range 22–396 cases per million smoker per year. The annual effective dose in general and for lungs in particular, the surface and mass exhalation rate, the equivalent equilibrium concentration of radon, and absorbed dose to tissues and lungs were calculated. The highest values were obtained for MIA2 sample, and the lowest values, for SUM sample.