Radiochemistry最新文献

The concentration ratio of chemical elements in a water aerosol may differ significantly from the concentration ratio of the same elements in bulk water from which this water aerosol was generated. Fractionation of chemical elements in water aerosols occurs in the surface microlayer of water and is observed only for water-soluble trace elements. For radionuclides (trace elements), the relative fractionation factor F(X/Cs) is defined as the degree of accumulation of the activity of radionuclide X in the water aerosol relative to that of another (reference) radionuclide (¹³⁷Cs). The paper suggests a technique for field evaluation of relative fractionation factors for various trace elements in water aerosols that are generated by interaction of a stream of hot wastewater and cold lake water. During this interaction, air dissolved in the cold water passes into the gas phase in the form of bubbles. The technique was tested under natural conditions in the V-2 reservoir (Lake Kyzyl-Tash), in which the ⁹⁰Sr activity concentration in water was 1.4 kBq/L and concentration of basic trace chemical elements was less than ~10 mg/L. The relative fractionation factors F(Y/Sr) for various trace elements in the water aerosol were estimated at ~15 for aluminum, ~13 for iron, >15 for lead, >46 for zinc, ~1.1 for calcium, ~0.3 for magnesium, and ~30 for nickel. The absolute fractionation factors F(Y) for these elements were 5.5 times higher than the relative fractionation factors. The ⁹⁰Sr activity concentration in air in the vicinity of the V-2 reservoir for the period from March 21 till March 26, 2025 was estimated at ~0.2 mBq/m³ due to all sources of contamination, with the water aerosol generation contributing no more than 3%.

Clinoptilolites from the Shivyrtui and Kholinskoe deposits modified with manganese dioxide and with titanium hydroxide and phosphate, as well as manganese dioxide modified bentonite from the 10th Khutor deposit, were prepared. The physicochemical properties of the modified samples and their ability to take up strontium, cesium, uranium, and americium were studied. The cesium, strontium, and uranium adsorption isotherms were obtained over a wide concentration range. The distribution coefficients and the static exchange capacity of the materials were determined. The effect of solution pH on the sorption of ⁹⁰Sr onto natural and modified clinoptilolite and of ²⁴¹Am onto natural and modified bentonite was compared. The modified sorbents show promise for use within sorption barriers to immobilize ¹³⁷Cs, ⁹⁰Sr, uranium, ²⁴¹Am, and other transuranic elements. This would significantly reduce their migration into groundwater and enhance the safety of radioactive waste storage and disposal facilities.

³²P carriers based on calcium alginate and hydroxyapatite for potential application in nuclear medicine were studied. Alginate beads cross-linked with calcium and mineralized with nanocrystalline hydroxyapatite were synthesized. The samples were characterized by optical and electron microscopy, X-ray diffraction, and IR spectroscopy. The KH₂[³²P]O₄ sorption from an aqueous solution was proposed as a method for introducing radionuclides into alginate beads. The kinetics of this process and the effect of mineralization and swelling of the hydrogel in an aqueous medium and in saline were studied. Composite calcium alginate and hydroxyapatite beads took up 90% of the activity from a saline solution within 5 h. Mineralization with hydroxyapatite improved both the kinetic parameters of sorption and the retention of the radionuclide in an aqueous medium. Composite calcium alginate and hydroxyapatite beads can be recommended for further tests as applicator materials for surface brachytherapy with ³²P.

The kinetics of europium and yttrium extraction with mono- and polyfunctional ligands in organic diluents was studied by attenuated total reflection IR spectroscopy and a method using a diffusion cell. The extraction rate is influenced by the kind of the ligand, solvate formation mechanism, and specific features of diffusion. The extraction rate constants in the systems studied were calculated. In the extraction of europium with organophosphorus ligands, the extraction rate constants range from 3.3 × 10^–4 to 1.1 × 10^–3 cm s^–1. A stepwise complexation mechanism with polyfunctional ligands containing P=O and C=O groups was revealed. In the case of yttrium extraction, the extraction rate constant with a mixed extractant, 2,3-dihydroxynaphthalene + methyltrioctylammonium carbonate, is 1.5 × 10^–3 cm s^–1, which is higher by an order of magnitude than the rate constant obtained with 8-hydroxyquinoline (k = 4.3 × 10^–4 cm s^–1), owing to a synergistic effect.

The solubility of uranium dioxide in simulated groundwater from a radioactive waste disposal site, in microbiota solutions, and in solutions of organic substrates for its stimulation was studied. In Russia, surface storage facilities for radioactive waste are subject to conservation. One of its main stages is the remediation and decontamination of adjacent territories and groundwater, including bioremediation technologies. Uranium is the most dangerous radionuclide for all disposal sites, and the stability of its reduced, low-solubility forms plays a crucial role in remediation. This study was aimed at assessing the potential biogeochemical mobility of UO₂ in the upper horizons of groundwater near the Siberian Chemical Combine (SCC) reservoir that underwent bioremediation in 2015. It was found that uranium dioxide is generally quite stable in microaerobic aquatic environments. Its solubility slightly increased in experiments with the stimulation of microbiota development, probably owing to nitrate-dependent oxidation processes and the release of metabolites that can form soluble complexes with uranium. However, in general, the groundwater bioremediation does not pose significant risks of remobilization of reduced uranium species.

Radon, a naturally occurring radioactive gas in soil, has a profound effect on the local air quality and poses health risks to nearby populations. The disturbance of the Earth’s surface through excavation activities can enhance the release of these gases, increasing the likelihood of the ²²²Rn exposure. This study investigates soil samples collected from various sites across the Pshdar region in Iraq to provide a comprehensive evaluation of the area’s radiological profile. The objective is to determine the concentrations of alpha emitters ²²²Rn, ²²⁶Ra, and ²³⁸U present in the soil. Alpha particles emitted from ²²²Rn gas were recorded using CR-39 detector. To enlarge and reveal the alpha tracks, the samples underwent chemical etching using a 6.25 N NaOH solution at 60°C for 6 h, after which the tracks were analyzed under an optical microscope. The mean concentrations of ²²²Rn, ²²⁶Ra, and ²³⁸U were 170 Bq m^–3, 0.32 Bq kg^–1, and 4.16 ppm, respectively. These results were within the safe limit. Radiological hazard parameters for indoor and outdoor (annual effective dose, excess lifetime cancer risk, and effective dose rate to different body organs) were computed to assess the health risks associated with selected soil samples. The results of the study indicate that the levels of alpha-emitting radionuclides in the soil samples were below the recommended safety thresholds, suggesting that the surveyed area does not pose a radiological hazard. These findings offer important baseline data to support Iraqi public health initiatives and ²²²Rn management strategies.

The impact of the concentration of the initial nitric acid actinide solutions on the thermochemical denitration in a thin-film rotary apparatus, on the entrainment of actinides into a local gas purification system, and on the physicochemical and some technological characteristics of the obtained uranyl(VI)–thorium formate powders (with thorium taken as a plutonium simulator) was determined. At the initial U + Th concentration in the solution of 200 g/L, the productivity was 65.20 g/h, the bulk density with/without tapping was 841 ± 45/704 ± 31 g/dm³, and the specific surface area was 0.69 ± 0.07 m²/g. The particle shape is predominantly spheroidal, which, in our opinion, will favor good fluidity of the powder during the reduction in a rotary tube furnace installed in the existing production facility for producing a pilot batch of uranium–plutonium oxide fuel.

The possibility of using polyethylene glycols and crown ethers in the extraction of radionuclides into liquefied Freon HFC-134a was examined. The use of Zonyl FS-300 fluorinated polyethylene glycol as a ligand in radionuclide extraction into liquefied Freon HFC-134a was suggested. The new ligand exhibits high performance in the extraction of alkali and alkaline earth metals. The effect of counterions on the extraction of metals in systems with Zonyl FS300 was examined.

Yttrium-90 is a promising therapeutic radionuclide for nuclear medicine with wide application in radiotherapy of liver cancer and metastases by means of transarterial radioembolization using polymer and glass microspheres, as well as in the treatment of rheumatoid arthritis and osteoarthritis with [⁹⁰Y]yttrium citrate colloids. Low-specific-activity ⁹⁰Y, available from research nuclear reactor via ⁸⁹Y(n,γ)⁹⁰Y reaction, suits well for these purposes. In recent years, great interest has been focused on highly specific radiopharmaceuticals (RPs) labeled with ⁹⁰Y for peptide-receptor radiotherapy, radioimmunotherapy, and radioligand radiotherapy. Syntheses of the RPs requires ⁹⁰Y of high specific activity, produced in ⁹⁰Sr/⁹⁰Y isotope generators. The parent radionuclide ⁹⁰Sr is readily available as the main component of nuclear fuel waste. This review examines the main approaches to developing different types of generators using extraction, sorption, and electrochemical methods, as well as their combinations. It also provides an overview of the main classes of ⁹⁰Y-based radiopharmaceuticals used in targeted radionuclide therapy for various tumors.

Crystalline silicophosphates M₂Zr₂SiP₂O₁₂ (M = K, Rb, Cs) of langbeinite structure were synthesized using the sol–gel method. These materials are of interest as candidate matrices for incorporating radioactive elements that are produced during the reprocessing of irradiated nuclear fuel. The composition, morphology, and structure of the samples as a function of the synthesis temperature were studied by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray microanalysis. Single-phase silicophosphates were obtained at 800°C. The sintering of M₂Zr₂SiP₂O₁₂ samples by hot pressing was described in terms of time and temperature. The thermal stability of silicophosphates up to 1200°C was confirmed by thermo-XRD and combined TG–DSC analyses. Silicophosphates are isotropic, moderately expanding materials; the coefficient of linear thermal expansion of Cs₂Zr₂SiP₂O₁₂ is 5.8 × 10^–6 °C^–1. The 28-day dynamic chemical durability test showed that the leach rate of Cs⁺ ions from the ceramics of langbeinite structure in distilled water at 90°C was approximately ~10^–5 g cm^–2 day^–1.