Papers by Keyword: Radionuclides

Abstract: This paper presents the physical and chemical properties of fly ash obtained from two coal power plants; the Sultan Salahuddin Abdul Aziz Power Plant in Kapar, Selangor and Sultan Azlan Shah Power Plant in Manjung, Perak. Moisture and radionuclide contents, and chemical composition in the fly ash were characterized. It was found that moisture content for Kapar and Manjung fly ash were at 0.41% and 0.11%, respectively. XRF result showed that Kapar fly ash sample is of class C due to the total percentage of SiO2, Al2O3, and Fe2O3 being less than 70% while Manjung fly ash sample is of class F due to the total percentage of SiO2, Al2O3, and Fe2O3 of more than 70%. Gamma spectrometry analysis indicated presence of ²²⁶Ra, ²³²Th, and ⁴⁰K in the samples. These data can be used to establish a technical standpoint in supporting the development of radioactive waste immobilization technology using geopolymer material. This study is expected to benefit the nuclear fuel cycle specifically in conditioning of low-level radioactive waste produced in nuclear power plants.

Abstract: Представлен оригинальный метод получения композиционных сорбционных материалов на основе смешанных ферроцианидов Ni-K и Zn-K в композиции с силоксан-акрилатной эмульсией и полиэтиленом. Оригинальность метода заключается в гидрофобизации материала за счет введения полиэтиленовых волокон в структуру ферроцианидов. Изучены особенности извлечения микро- и микроконцентраций катионов Cs ⁺ , а также радионуклидов Cs-137 из морской воды в статических и динамических условиях. Экспериментальные значения сорбции аппроксимируются согласно уравнениям Фрейндлиха, Ленгмюра, Ленгмюра-Фрейндлиха, а значения максимальной сорбции G _max и константы адсорбционного равновесия K _lрассчитаны. Установлено, что сорбенты, синтезированные с использованием полиэтилена, при степени очистки морской воды от ионов цезия до 99% обладают наилучшими сорбционными характеристиками. Значения K _p для цезия при использовании исследуемых сорбентов могут достигать 10 ⁵ мл / г, что свидетельствует об их перспективности для очистки морской воды от радиоактивного цезия. Описанный подход является примером простого и доступного технологического синтеза эффективных и востребованных на практике сорбентов высокого эксплуатационного качества.

Abstract: Almost all hospitals use radioisotopes for different purposes, as their applications grow, so their concentration in the waste of those hospitals does. To address this issue, twenty-nine samples were collected from (9) sites, these samples were collected from the incinerators of medical areas and the waste collection chambers. After collecting the samples, they were prepared for the examination, where a high-purity Germanium detector (HPGe) was used to detect radioactive elements. The lead element (Pb-214) of the uranium chain (U-238) and the actinium element (Ac-228), the lead element (Pb-212) of the thorium chain (Th-246) and the potassium element (K-40) appeared in some medical areas Iodine (I-131). Some regions showed high concentrations of these elements compared to some sites, Iodine (I-131) appeared in high rates in some hospitals specialized in treating cancerous diseases. The equivalent efficacy of radium, the annual equivalent internal and external dose, and the internal and external risk factors were calculated and the results obtained were compared with the global limits.

Abstract: In this article, both the composition and composite properties of radioactive sources for medical applications are worked out and studied. The bases of these sources are bioinert ceramic solids and radionuclides. The active source is constituted from dispersed radioactive yttriа oxide or strontium oxide monolithically encapsulated with bioinert glass flux. The thermal expansion properties of the analyzed composites are highly similar to the ones of both titanium metal and titanum alloys. Therefore, the developed radioactive sources can be mounted on titanium holder. Importantly, all utilized elements and alloys are already applied in medicine. In this article we demonstrate the use of a radioactive β-source placed on a titanium holder. The device is finally applied in a oncological model disease treatment.

Abstract: Radionuclides released from uranium mine ventilation shafts would pose radiation exposure to the public and environment. A three-dimensional lagrangian stochastic model has been presented to study the atmospheric dispersion of solid-state radionuclides released from the uranium-bearing mine ventilation shafts. Meteorological conditions and geographical conditions including four downwind velocities (0.5, 1.0, 2.0, 4.0 m/s) and two underlying surface roughness characteristics (0.1 m, 1.0 m) were chose in the study. The radionuclides concentration distributions at various wind speeds and surface roughness were attained to evaluate the pollution in the vicinity of uranium mine ventilation shaft.

Abstract: Microbial cell – soluble species interactions can be part of technologies for the treatment of metal/metalloid and radionuclide bearing water streams in order to sequester the targeted species. Interactions of microbial cells and soluble targeted species include passive and active processes of metabolically inactive or active biomass, and result in the reduction of their mobility and toxicity. Different parts of the cell may sequester targeted species via processes such as complexation, chelation, coordination, ion exchange, precipitation and reduction. Collectively, these mechanisms have been referred to as sorption and the overall phenomenon as biosorption. The term biosorption is generally used to describe the passive interaction of microbial biomass with targeted species. The technologies based on these processes, lead to the set up of units, mainly in the form of packed bed reactors similar to the configuration of ion exchange resins reactors, placed at the end of a treatment process as a polishing stage. In order to maintain durability of the sorbent, the microbial cells harvested from different sources, are formulated into particles by way of immobilization – pelletization. In the early years of Biosorption, a significant effort was devoted to study the reusability of the sorbent by repeated sorption – desorption cycles, in order to reduce the operating cost of the technology. The availability of the biosorbent material, the reversibility of the desorption process, the presence of competing co-ions and organic molecules, posed significant scepticism and finally serious doubt about the industrial applicability of biosorption as a stand alone technology. However the mechanisms are active and present in biological reactors, and can contribute to overall species sequestering. Biological reactors based on active microbial biomass as alternative to passive sorption, exploit the self regenerating features of living biomass along with the traits of microbial metabolism. Active cells produce metabolites (i.e. EPS, simple inorganic moieties etc.) interacting chemically with the targeted species. The active biomass offers the additional attractive feature of forming biofilms on the surface of carrier materials allowing a natural way of cell immobilization. Different biofilm reactor configurations e.g. static or moving bed filters, fluidized bed reactors, rotating biological contactors support the development of biofilms. Conditions such as temperature, pH, presence of toxic compounds etc. should be considered in the applicability of the technology. Important metabolically mediated immobilization processes for metal/metalloid and radionuclide species are bioprecipitation and bioreduction. Bioprecipitation processes include the transformation of soluble species to insoluble hydroxides, carbonates, phosphates, sulfides or metal – organic complexes as a result of the microbial metabolism. In the case of biological reduction, the cells may use the species as terminal electron acceptors in anoxic environments to produce energy or reduce the toxicity of the cells microenvironment. Such processes form the basis for treatment technologies which are recently developed and applied both in pilot and full scale.