Letteratura scientifica selezionata sul tema "Radioactif element"
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Articoli di riviste sul tema "Radioactif element":
1
García, Adrián Carrillo, Mohammad Latifi, Ahmadreza Amini e Jamal Chaouki. "Separation of Radioactive Elements from Rare Earth Element-Bearing Minerals". Metals 10, n. 11 (17 novembre 2020): 1524. http://dx.doi.org/10.3390/met10111524.
Abstract (sommario):
Rare earth elements (REE), originally found in various low-grade deposits in the form of different minerals, are associated with gangues that have similar physicochemical properties. However, the production of REE is attractive due to their numerous applications in advanced materials and new technologies. The presence of the radioactive elements, thorium and uranium, in the REE deposits, is a production challenge. Their separation is crucial to gaining a product with minimum radioactivity in the downstream processes, and to mitigate the environmental and safety issues. In the present study, different techniques for separation of the radioactive elements from REE are reviewed, including leaching, precipitation, solvent extraction, and ion chromatography. In addition, the waste management of the separated radioactive elements is discussed with a particular conclusion that such a waste stream can be employed as a valuable co-product.
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Wu, Dun, Yuanyuan Wang, Meichen Wang, Chao Wei, Guangqing Hu, Xiaoli He e Wei Fu. "Basic Characteristics of Coal Gangue in a Small-Scale Mining Site and Risk Assessment of Radioactive Elements for the Surrounding Soils". Minerals 11, n. 6 (18 giugno 2021): 647. http://dx.doi.org/10.3390/min11060647.
Abstract (sommario):
The accumulation/improper treatment of coal gangue will not only lead to waste of land, but also cause environmental pollution. Especially the impact of radioactive elements on the surrounding ecological environment is widely concerned by many scholars. In this study, the concentration of radioactive elements (uranium (U) and thorium (Th)) of small-scale coal gangue mining site and surrounding soil in the northern region of Xieqiao coal mine were tested, the material composition of coal gangue was analyzed via XRF and XRD, the modes of occurrence of U and Th elements were investigated, and their potential ecological risks and ecological effectiveness were evaluated. The results show that the clay minerals with high content in coal gangue are the key minerals for the adsorption of uranium and thorium in coal gangue. The specific activity of two radioactive elements (U and Th) in soil is much lower than that of coal gangue. With the increase of the distance from the soil collection point to the gangue piles and the depth of the soil profile, the specific activities of the two radioactive elements decrease gradually. On the basis of the concentration curve, the range of the radioactive contamination halo of gangue piles is limited (≤30 m), speculating qualitatively that the gangue dump has no significant influence on the radioactivity of the surrounding water. The modes of occurrence of U and Th in coal gangue and soil are altered. According to the index of geo-accumulation, Th is easier to accumulate in soil environment, but Th and U pollution in soil is not obvious. In contrast to U element, the active state of Th element in soil is generally affected by exogenous (coal gangue) export, which may have a potential environmental effects. This study provides a research idea for the investigation of radioactive element pollution to the surrounding soil in small-scale coal gangue plies.
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Holden, Norman E., Tyler B. Coplen, John K. Böhlke, Lauren V. Tarbox, Jacqueline Benefield, John R. de Laeter, Peter G. Mahaffy et al. "IUPAC Periodic Table of the Elements and Isotopes (IPTEI) for the Education Community (IUPAC Technical Report)". Pure and Applied Chemistry 90, n. 12 (19 dicembre 2018): 1833–2092. http://dx.doi.org/10.1515/pac-2015-0703.
Abstract (sommario):
AbstractThe IUPAC (International Union of Pure and Applied Chemistry) Periodic Table of the Elements and Isotopes (IPTEI) was created to familiarize students, teachers, and non-professionals with the existence and importance of isotopes of the chemical elements. The IPTEI is modeled on the familiar Periodic Table of the Chemical Elements. The IPTEI is intended to hang on the walls of chemistry laboratories and classrooms. Each cell of the IPTEI provides the chemical name, symbol, atomic number, and standard atomic weight of an element. Color-coded pie charts in each element cell display the stable isotopes and the relatively long-lived radioactive isotopes having characteristic terrestrial isotopic compositions that determine the standard atomic weight of each element. The background color scheme of cells categorizes the 118 elements into four groups: (1) white indicates the element has no standard atomic weight, (2) blue indicates the element has only one isotope that is used to determine its standard atomic weight, which is given as a single value with an uncertainty, (3) yellow indicates the element has two or more isotopes that are used to determine its standard atomic weight, which is given as a single value with an uncertainty, and (4) pink indicates the element has a well-documented variation in its atomic weight, and the standard atomic weight is expressed as an interval. An element-by-element review accompanies the IPTEI and includes a chart of all known stable and radioactive isotopes for each element. Practical applications of isotopic measurements and technologies are included for the following fields: forensic science, geochronology, Earth-system sciences, environmental science, and human health sciences, including medical diagnosis and treatment.
4
Yeşiloğlu, Sevinç Nihal. "Investigation of pre-service chemistry teachers’ understanding of radioactive decay: a laboratory modelling activity". Chemistry Education Research and Practice 20, n. 4 (2019): 862–72. http://dx.doi.org/10.1039/c9rp00058e.
Abstract (sommario):
The first purpose of this study was to introduce a laboratory modelling activity focusing on teaching the concepts of radioactive elements/atoms, radioactive decay, and half-life. The second was to investigate pre-service chemistry teachers’ understanding of these concepts. Fifteen pre-service chemistry teachers who had enrolled in a Physical Chemistry Laboratory course participated in the study. The participants simulated the radioactive decay process of an imaginary radioactive element called Cornium during the laboratory modelling activity. In this way, pre-service chemistry teachers were able to visualize and model what is meant by radioactive decay and half-life. Data sources included responses given to open-response conceptual questions, participants’ drawings about radioactive decay and half-life, semi-structured interviews, activity worksheets, and observation notes. Qualitative analysis of data revealed that the pre-service chemistry teachers had misconceptions about the definition of radioactive elements/atoms, radioactive decay, and the half-life process before the activity. The role of the modelling activity in exposing and eliminating these misconceptions was discussed.
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Gurin, A., Y. Chakrova, Z. Medvedeva, V. Zakharov e Y. Kulakova. "ANALYSIS OF THE PRODUCTION OF RARE-EARTH ISOTOPES AT THE WWR-K RESEARCH REACTOR: PROMISING THERAPEUTIC RADIONUCLIDES". NNC RK Bulletin, n. 4 (29 dicembre 2023): 40–46. http://dx.doi.org/10.52676/1729-7885-2023-4-40-46.
Abstract (sommario):
Rare Earth Elements (REE) are a group of seventeen chemical elements in the periodic table, including lanthanides and scandium and yttrium. These elements have unique physical and chemical properties that make them valuable in various industries, including electronics, magnets, and catalysts. However, radioactive isotopes of rare earth elements also possess effective nuclear physical properties that make them promising for the development of new radiopharmaceuticals for therapeutic purposes. These radioactive isotopes have unstable atoms with excess nuclear energy, and they undergo radioactive decay, which can be utilized for medical applications.The nuclear physical properties of radioactive isotopes of rare earth elements make them suitable for therapeutic purposes in medicine. For example, technetium-99m, a radioactive isotope of technetium, is widely used in diagnostic nuclear medicine due to its outstanding physical-chemical characteristics. Other radioactive isotopes of rare earth elements, such as holmium-166, have been established for a broad spectrum of medical applications. These isotopes can be used in targeted radiation therapy to treat various diseases, including cancer. The unique properties of these radioactive isotopes allow for precise targeting and delivery of radiation to specific tissues or cells, minimizing damage to healthy tissues.The potential of radioactive isotopes of rare earth elements for therapeutic purposes extends beyond the current applications. Ongoing research and innovations in the field of radiopharmaceuticals continue to explore the use of underutilized lanthanoid radionuclides for theranostic purposes. For example, astatine, a rare and highly radioactive element, exhibits multiple isotopes that can be potentially utilized in targeted therapy. The development of new radiopharmaceuticals using radioactive isotopes of rare earth elements holds promise for advancing medical treatments and improving patient outcomes. With further research and advancements, these isotopes may play a crucial role in the future of therapeutic medicine.This research work makes it possible to evaluate the possibility of obtaining REE such radioisotopes as: 90Y, 141Ce, 147Nd, 153Sm, 165Dy, 166Ho, 169Tm, 175Yb, 177Yb, 177Lu by reaction (n, γ) at the WWR-K reactor.
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Przylibski, Tadeusz Andrzej. "Radon: a radioactive therapeutic element". Geological Society, London, Special Publications 451, n. 1 (2 dicembre 2016): 209–36. http://dx.doi.org/10.1144/sp451.7.
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Marwan Rasheed Abass. "Measurement of radon concentration for models of living and non-living things in Samarra and its environs". Tikrit Journal of Pure Science 20, n. 1 (8 febbraio 2023): 140–43. http://dx.doi.org/10.25130/tjps.v20i1.1147.
Abstract (sommario):
This research included a study of the proportion of radioactive elements naturally and in particular element of radioactive radon in parts of the body directly relevant to the lives of human organisms in Samarra and its surroundings , where collected samples from the teeth of human bones and some animals (cattle , sheep , goats and chickens , local fish and imported ) , as well as some of the pastes Tooth based on the principle that radioactive elements are concentrated in the bones for living organisms using reagents nuclear effect SSNTDs Results indicated that the largest gas radon concentration was in the bones of cows 1932 ± 162 and less concentration of radon was in a group dental age 45 years 198 ± 243 As for the toothpaste was the highest concentration in the teeth Sensodyne toothpaste 186 ± 150 and less concentration in toothpaste devoted 167 ± 123.
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., Irvani, e Janiar Pitulima. "PROMINE". PROMINE 5, n. 2 (3 gennaio 2017): 36–41. http://dx.doi.org/10.33019/promine.v5i2.916.
Abstract (sommario):
As one of the island that producing tin ore mineral (cassiterite), Bangka Island has probably a bigpotential of tin associated mineral that contains radioactive elements like Thorium (Th) and Uranium(U). Th and U can be one of potential future prospect elements expecially for nuclear energy. Th andU elements bearing minerals in Bangka Island not yet exploited. They take out from the tin ore miningand becoming tailing, and then through the surface water flows or shallow sea water as sediment. Thestudy goal is to getting the number of radioactive Th and U elements using surface sediment sampleand then interpretation some part of their spatial distribution form. The Surface sediment data hasbeen collected on 2 sites Kolong in Muntok District West Bangka Regency, 3 sites in MerawangDistrict Bangka Regency, 9 sites in Pangkalpinang City, 2 sites in Central Bangka Regency and 2sites in South Bangka Regency. Chemistry analysis of sediments for identification the presence of Thand U elements. Radioactive element of Uranium (U) almost presence at all shallow surfacesediment 4.842 - 229.2 ppm except nul in 1 sample. Thorium (Th) just presence in a part of sedimentsample. One site as especially case study Kacang Pedang Retention Ponds, shows Th and Uradioactive elements has the heterogenity spatial pattern.
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Budin, O. N., I. V. Kuznetsov, M. Y. Kalenova, S. A. Krasikov e A. S. Shchepin. "DISTRIBUTION OF RADIOACTIVE ELEMENTS DURING SLAG REMELTING OF STRUCTURAL MATERIALS OF VVER FUEL ELEMENT SHELLS". Расплавы, n. 2 (1 marzo 2023): 113–21. http://dx.doi.org/10.31857/s0235010623020020.
Abstract (sommario):
At the radiochemical plant of FSUE “PO “Mayak” in the process of processing spent nuclear fuel (SNF), about 170 tons/year of metal radioactive waste (MRW) are formed, mainly represented by fuel element shells structural materials (SM) containing residual amounts of radionuclides after fuel dissolution, and spent fuel assemblies (SFAS) sent to storage. It is possible to achieve compaction and decontamination of MRW by a method based on slag remelting in an induction furnace with a cold crucible. In order to establish the distribution of actinides and fission products (FP), thermodynamic slag remelting process modeling of the VVER-1000 reactor plant SM fuel rods shells and SFAS, experimental data obtained verification were carried out. The most probable distribution of actinides and FP by melting products is shown. Most of the curium and americium are concentrated in the metal – 99 and 94 wt %, respectively. The maximum extraction of uranium into the slag phase in the form of UO2 dioxide is up to 40 wt %. The distribution of plutonium in the temperature range of 1500–2000°C over the slag (in the form of PuO and PuO1.61 oxides) and metal phases occurs in almost equal proportions. It has been established that up to 99.78 wt % cesium, the content of europium and americium is 0.05 and 0.17 wt %, respectively.
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Tanaka, Masaomi, Daiji Kato, Gediminas Gaigalas, Kyohei Kawaguchi, Laima Radžiūtė, Pavel Rynkun, Smaranika Banerjee e Nanae Domoto. "Modeling kilonova emission from neutron star mergers". Proceedings of the International Astronomical Union 16, S363 (giugno 2020): 127–34. http://dx.doi.org/10.1017/s1743921322000850.
Abstract (sommario):
AbstractCoalescence of binary neutron stars gives rise to kilonova, thermal emission powered by radioactive decays of newly synthesized r-process nuclei. Observational properties of kilonova are largely affected by bound-bound opacities of r-process elements. It is, thus, important to understand atomic properties of heavy elements to link the observed signals with nucleosynthesis of neutron star mergers. In this paper, we introduce the latest status of kilonova modeling by focusing on the aspects of atomic physics. We perform systematic atomic structure calculations of r-process elements to understand element-to-element variation in the opacities. We demonstrate that the properties of the atomic structure of heavy elements are imprinted in the opacities of the neutron star merger ejecta and consequently in the kilonova light curves and spectra. Using this latest opacity dataset, we briefly discuss implications for GW170817, expected diversity of kilonova emission, and prospects for element identification in kilonova spectra.
Tesi sul tema "Radioactif element":
1
Giraud, Albert. "Couplages thermo-hydro-mécaniques dans les milieux poreux peu perméables : application aux argiles profondes". Marne-la-vallée, ENPC, 1993. http://www.theses.fr/1993ENPC9310.
Abstract (sommario):
De nombreuses applications industrielles de génie civil, de génie pétrolier et de génie minier nécessitent la résolution de problèmes mettant en jeu des couplages entre les comportements thermique, hydraulique et mécanique des géomatériaux. La démarche adoptée dans cette étude consiste à examiner divers modèles de comportement, en suivant une progression depuis les modèles les plus simples jusqu'a des modèles plus complexes. Des comparaisons sont effectuées sur des problèmes à géométrie simple (problèmes faisant intervenir une seule variable d'espace). On présente dans une première partie une méthode de résolution directe de problèmes de dégagement de chaleur en thermo-poro-élasticité linéaire, en milieux infinis ou semi-infinis. Des solutions et des applications sont présentées sur différents problèmes liés au projet de stockage de déchets radioactifs. Ces études permettent de dégager les paramètres déterminant l'importance des couplages thermo-hydro-mécaniques, par exemple le rapport entre les diffusivités hydraulique et thermique. L'étude du comportement irréversible des milieux poreux saturés nécessite une approche numérique. On a développé le code de calcul aux éléments finis thyme adapté à l’étude des problèmes de couplages thermo-hydromécaniques sur des structures à géométrie simple. Ce code est utilisé pour étudier le comportement différé de cavités souterraines excavées dans les argiles profondes. On commence par étudier les effets différés liés à la diffusion de la masse fluide, puis, dans le cas d'une argile raide les effets différés liés également à la viscosité. On étudie enfin le problème de l'empilement de conteneurs de déchets enfouis dans l'argile de boom.
2
Gérard, Bruno. "Contribution des couplages mécanique-chimie : transfert dans la tenue à long terme des ouvrages de stockage de dechets radioactifs". Cachan, Ecole normale supérieure, 1996. http://www.theses.fr/1996DENS0017.
Abstract (sommario):
Une prédiction fiable du comportement a long terme des barrières de confinement en béton nécessite d'avoir bien identifie les divers mécanismes de détérioration et de les avoir convenablement modélisés. L'originalité de cette étude est de coupler le comportement mécanique avec une dégradation d'origine chimique (dissolution des hydrates cimentaires due a un ruissellement d'eau pure). Afin d'évaluer ce couplage, un modèle a été développé et implanté dans un code de calculs par éléments finis. Le module d'élasticité évolue comme une fonction d'une variable de vieillissement dépendant de la teneur locale en calcium. Le comportement mécanique non-linéaire du béton est modélisé selon la théorie de l'endommagement. Parallèlement, deux procédures expérimentales ont été développées. La procédure bipède a été développée afin d'étudier les mécanismes de développement de la fissuration et des propriétés de permutation sous chargement mécanique de traction. La procédure lift a été développée pour la réalisation accélérée d'échantillons cimentaires dégradés chimiquement dans le but d'évaluer le couplage mécanique-chimie. Des essais de micro dureté ont été réalisés pour identifier la fonction de vieillissement chimico-mécanique. Plusieurs simulations numériques ont été réalisées. La présence d'une fissure modifie localement la pénétration de la dégradation. L'ouverture de la fissuration constitue un paramètre dominant le couplage diffusion-chimie-mécanique. A l'issue de ces simulations, plusieurs applications industrielles sont directement envisageables. Les limitations et les extensions futures du modèle ont aussi été discutées
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Medina, Molano Natalia Stefania. "Contribution of radioactivity to catalytic performance in heterogeneous media". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILR025.
Abstract (sommario):
Afin d'établir des voies possibles d'utilisation de métaux nobles récupérées du combustible nucléaire tels que le 107Pd, la présente thèse vise à étudier l'effet du rayonnement dans trois applications différentes : la catalyse hétérogène, avec - comme réaction modèle - l'hydrogénation du cinnamaldéhyde (CNA) ; la photocatalyse, avec - comme réaction modèle - la décoloration de l'orange de méthyle (MO) et la régénération des catalyseurs, désactivés lors de la synthèse de l'hydroxyméthyl furfural. Des protocoles ont été élaborés pour répondre aux exigences de sécurité nucléaire : applicable en boîte à gant et sorbonne, selon le cas.Le rayonnement β émis par le 107Pd n'a montré aucun effet lors de l'hydrogénation du CNA, indépendamment des conditions de réaction. En revanche, la décoloration a été initié par la présence de la radiation β sur le catalyseur en substituant de la lumière visible. Une diminution de l'absorbance (au point isosbéstique) a été observée. Ce dernier corrélait avec la quantité de catalyseur radioactif, mettant en évidence l'activation par le rayonnement β. Enfin, la régénération du catalyseur à base de Pd a donné des résultats prometteurs après l'irradiation γ, montrant notamment une augmentation de la performance catalytique après irradiation du catalyseur désactivé. Par ailleurs, le catalyseur à base de Ru, bien que généralement peu performant, a montré une activité plus élevée que l'activité du catalyseur frais après irradiation par rayonnement This thesis aimed to identify applications of noble metals recovered from spent nuclear fuels such as 107Pd. To study the effect of the radiation three different applications were selected: heterogeneous catalysis, with the hydrogenation of cinnamaldehyde (CNA) as model reaction; photocatalysis, with the decolourisation of methyl orange (MO) as model reaction; and the regeneration of catalysts, deactivated with the synthesis of hydroxymethyl furfural. Protocols were developed for the synthesis of the catalysts and the performance testing in restricted nuclear environment, namely in glove box and for the implementation of the reactions in glove box and extractor column as appropriate.Regarding the results it was found that β-radiation did not show any effect on the hydrogenation of CNA independent of the applied reaction conditions. On the other hand, the decolourisation of MO was successfully activated by the β-radiation of the catalyst. A decrease in absorbance (at the isosbestic point) was observed and was correlated to the amount of the catalyst employed, evidencing the effect of the irradiation doses. Finally, the regeneration of the Pd-based catalyst showed promising results after γ-irradiation, notably with a partial recovery of the initial catalytic performance after -irradiation. Meanwhile, the Ru-based catalyst, although generally not performing well, showed increased activity compared to the fresh catalyst upon -irradiation
4
Massasso, Giovanni. "Entrapment of mobile radioactive elements with coordination polymers and supported nanoparticles". Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20172/document.
Abstract (sommario):
La production d'énergie nucléaire nécessite des systèmes avancés pour améliorer les procédures de stockage et de confinement des déchets radioactifs. Par ailleurs, la capture d'éléments radioactifs mobiles dans les effluents des centrales nucléaires demande une amélioration de la capacité et de la sélectivité. L'iode 129-I est un des produits les plus critiques à confiner et il est produit pendant les procédés de recyclage des déchets nucléaires. Dans ce travail de thèse, la classe de matériaux moléculaires, dénommée structures de type Hofmann, a été étudiée en tant que matériaux massifs et nanoparticules supportées pour la capture sélective de l'iode moléculaire. En premier lieu, les matériaux M'(L)[M''(CN)4] ont été précipités sous la forme de poudres microcristallines. L'insertion d'iode dans le réseau des matériaux massifs a été effectuée par différents protocoles: 1) adsorption d'iode dans des solutions de cyclohexane à température ambiante; 2) adsorption d'iode en phase gazeuse à 80 °C; 3) adsorption de vapeurs d'iode en phase gazeuse à 80 °C et en présence de vapeurs d'eau. Les différents protocoles pour l'insertion d'iode n'ont pas influencé la nature de l'iode confiné. Pour la capture en solution, les structures NiII(pz)[NiII(CN)4], NiII(pz)[PdII(CN)4] et CoII(pz)[NiII(CN)4] ont montré une capacité d'une molécule d'iode par unité de maille. L'iode confiné est physisorbé en tant qu'iode moléculaire en interaction avec le réseau. Les modélisations GCMC ont confirmé la capacité maximale et ils ont indiqué que l'iode interagit avec la pyrazine et avec les cyanures. Sur la base des données expérimentales, la modulation des métaux dans le réseau a montré une légère différence dans la force d'interaction entre l'iode et le réseau et une adaptation de la maille spécifique pour chaque composition. Une complète régénération du réseau a été possible, puisque l'iode était complètement désorbé avant la décomposition du réseau. Pour le réseau NiII(pz)[PtII(CN)4], on a observé un mécanisme différent de capture puisque ce réseau contenant Pt a réagi avec l'iode en donnant le complexe de coordination NiII(pz)[PtII/IV(CN)4].I-. La formation de ce type de complexe était déjà observée dans la littérature par Ohtani et al. lesquels avaient préparé le complexe via une synthèse in-situ. Ensuite, le changement du ligand organique pyrazine avec d'autres ligands plus longs, c'est-à-dire la 4,4'-bipyridine (bpy) ou 4,4'-azopyridine (azpy), pour avoir des cages plus grandes a montré une diminution de la capacité maximale de capture d'iode. Les données expérimentales ont suggéré que pour un confinement d'iode optimisé, le réseau doit disposer de cages avec une dimension très proche de la molécule d'iode (0.5 nm). Après l'étude des matériaux massifs, nous avons considéré la préparation de nanoparticules supportées de NiII(pz)[NiII(CN)4] pour la capture d'iode. Nous avons obtenu les nanoparticules via un procédé étape par étape, par imprégnation d'une série de silices mésoporeuses greffées avec un ligand diamine, puis avec les précurseurs de NiII(pz)[NiII(CN)4]. Nous avons utilisé en tant que supports, une silice SBA-15 modifiée et des billes de verre poreux pour obtenir respectivement les nanocomposites Sil@NP and Glass@NP. Par microscopie électronique à transmission, nous avons détecté pour Sil@NP des nanoparticules de diamètre moyen 2.8 nm. L'adsorption d'iode dans les nanoparticules a été confirmée par spectroscopie FT-IR. Les traitements thermiques ont indiqué que la portion d'iode dans les nanoparticules pouvait être désorbé dans l'intervalle 150-250 °C. Nous avons pu estimer que la capacité de capture des nanoparticles était très proche de la capacité du massif NiII(pz)[NiII(CN)4]@I2Nuclear power industry still demands further research to improve the methods for the storage and the confinement of the hazardous radioactive wastes coming from the fission of radionuclide 235U. The volatile radioactive 129I (half-life time 15x107 years) is one of the most critical products coming from the reprocessing plants in the fuel-closed cycles. In the present thesis the family of coordination solid networks, known as Hofmann-type structures, was studied in the form as both bulk and supported nanoparticles for the selective entrapment of the molecular iodine. This set of investigated materials exhibited a general formula M'(L)[M''(CN)4] where M' = NiII or CoII; L = pyrazine, 4,4'-bipyridine, 4,4'-azopyridine; M'' = NiII, PdII or PtII. Initially, the material NiII(pz)[NiII(CN)4] and its analogue structures were precipitated as microcrystalline bulky compounds and fully characterized. The insertion of the iodine in the bulky host structures was performed with different methods: 1) adsorption of iodine in solutions of cyclohexane at room temperature; 2) adsorption of iodine vapours at 80 °C; 3) adsorption of iodine vapours at 80 °C in presence of water steam (for few selected materials). The different methods did not affect the nature of the confined iodine. For the entrapment in solution, results indicated that the Hofmann-type structures NiII(pz)[NiII(CN)4], NiII(pz)[PdII(CN)4] and CoII(pz)[NiII(CN)4] could host one I2 molecule per unit cell. The iodine resulted physisorbed as molecular iodine in interaction with the host structure. GCMC simulations confirmed the maximal capacities and indicated that iodine could interact with both the pyrazine and the coordinated cyanides. Experimentally, however, the modulation of the metals showed a slightly different strength of interaction I2-lattice bringing to a different lattice adaptation. The materials also could be fully regenerated since the complete desorption of iodine occurred before the decomposition of the host structure. Reiterated adsorption-desorption steps (3 cycles) on the networks NiII(pz)[NiII(CN)4] and NiII(pz)[PdII(CN)4] indicated an excellent structural resistance to cycling and a maintained high capacity. A different mechanism of confinement was detected for the structure NiII(pz)[PtII(CN)4] which reacted with iodine giving complex NiII(pz)[PtII/IV(CN)4].I-. Finally, the modulation of the organic ligand L indicated that the replacement of the ligand pyrazine with longer ligands, to obtain larger pores, had a detrimental effect on the maximal iodine loading due to a weaker confinement. After the study of the bulk materials, we considered the preparation of supported nanoparticles of NiII(pz)[NiII(CN)4] for the entrapment of iodine. The nanoparticles were obtained by a step-by-step method, impregnating a set of diammine-grafted mesoporous silicas with the precursors of NiII(pz)[NiII(CN)4]. We detected nanoparticles with mean size 2.8 nm by transmission electronic microscopy. The insertion of iodine in the nanoparticles was confirmed by FT-IR. Thermal treatments indicated that the portion of iodine inside the nanoparticles could be reversibly desorbed in the range 150-250 °C and reintroduced in a cyclic process. It was estimated that the amount of physisorbed iodine in the NPs, with respect to the amount of deposited NPs matched with the maximal capacity NiII(pz)[NiII(CN)4]@I2
5
Sercombe, Jérôme. "Modélisation du comportement du béton en dynamique rapide application au calcul des conteneurs à haute intégrité". Marne-la-vallée, ENPC, 1997. http://www.theses.fr/1997ENPC9721.
Abstract (sommario):
Ce travail porte sur la modélisation du comportement du béton en dynamique rapide et son application au calcul des structures et ouvrages en béton, béton armé et béton de fibres. Il présente, d’une part, le développement d’une loi de comportement adaptée au matériau béton en dynamique, et d’autre part, le développement des algorithmes nécessaires à sa mise en œuvre dans un code de calculs par éléments finis. Enfin, une partie importante de ce travail concerne l’application de ce modèle à un problème industriel concret : l’étude prédictive de la réponse de conteneurs en béton de fibres, utilisée pour le stockage des déchets radioactifs, suite à l’impact résultant d’une chute libre de 5 mètres. La modélisation des différents aspects du comportement du béton en dynamique (augmentation de résistance et de module d’élasticité avec la vitesse de chargement) est effectuée au niveau macroscopique en s’appuyant sur les résultats expérimentaux permettant d’identifier les paramètres importants dans le comportement du matériau à haute vitesse. Principalement, l’importance de l’eau dans les pores du béton sur ses propriétés mécaniques en dynamique conduit à introduire, dans une modélisation élasto-plastique du béton, une variable supplémentaire, prenant en compte ce paramètre au niveau macroscopique. Le développement de ce modèle couplé amène à définir une loi de comportement visco-élasto-plastique dans laquelle un concept nouveau, l’écrouissage visqueux, qui traduit l’évolution du seuil de plasticité avec la variable de déformation visco-élastique, est introduit pour modéliser au niveau macroscopique l’augmentation de résistance du béton avec la vitesse de chargement. Cette loi de comportement est alors implantée dans un code de calculs par éléments finis. L’intégration des contraintes visco-élasto-plastiques du modèle conduit au développement de deux algorithmes permettant une actualisation implicite ou explicite des variables du modèle. Le modèle est alors appliqué à la simulation de la réponse de structures simples soumises à des chargement dynamiques : éprouvettes en traction et compression simples, prismes en flexion simple et dalles armées testées au tube à choc. La comparaison avec les résultats expérimentaux permet de vérifier la précision du modèle et de définir ses limites. Enfin, afin de traiter le problème industriel à l’origine de cette thèse, la loi de comportement visco-élasto-plastique est appliquée à un béton de fibres à ultra haute résistance, le Béton de Poudres Réactives (BPR). Les paramètres du modèle sont estimés d’après des résultats d’essais de traction directe à différentes vitesses de chargement. Des simulations de chutes de conteneurs en BPR de différentes hauteurs sont alors présentées. La bonne corrélation entre les résultats numériques et expérimentaux, notamment en ce qui concerne l’évaluation de la hauteur de chute « critique », de l’orientation et de la position des fissures, du mode de ruine, montre l’intérêt du modèle pour les ingénieurs, notamment lors des études de pré-dimensionnementThis work is concerned with the modelling of concrete behaviour in high rate dynamics and its application to the finite element calculation of concrete, reinforced concrete and fiber-reinforced concrete structures. It consists, on the one hand, in the development of a suitable onstitutive law for concrete in dynamics and, on the other hand, in the development of algorithms for its integration in a finite element code. Finally, a major part of this work is dedicated to the treatment of an industrial application : the estimation of the response of fiber-reinforced concrete containers for radioactive waste when subjected to a 5 meter high drop test. Modelling of the main aspects of concrete behaviour in high rate dynamics (characterized by the increase of strenght and elastic modulus with the loading rate) is treated at the macroscopic level and is based on experimental results that clearly identify the important parameters in the behaviour of concrete at high loading rates. Mainly, the importance of the presence of water in the pores of concrete on its mechanical properties in dynamics, leads to the introduction of an additional variable in an elasto-plastic model for concrete, in order to account for this parameter at the macroscopic level. The development of this coupled model leads to a visco-elasto-plastic constitutive law in which a new concept, visvous hardening, which expresses the evolution of the plastic yield limit with a visco-elastic variable, is introduced to account at the macroscopic level for the strength enhancement observed in dynamics for concrete. This constitutive law is then implemented in a finite element program. The integration of the visco-elasto-plastic stresses leads to the development of two return mapping algorithms characterized by an implicit or explicit updating of the variables of the model. The model is then applied to the modelling of the response of simple structures subjected to dynamic loading : specimens tested in direct tension and compression, small beams tested in bending and reinforced slabs tested with a shock tube. The accuracy of the model and its limits are then evaluated through the comparison between experimental and numerical results. Finally, in order to treat the industrial problem at the origin of this thesis, the visco-elasto-plastic constitutive law is applied to an ultra high strength fiber reinforced concrete : the Reactive Powder Concrete (RPC). The parameters of the model are obtained through direct tensile tests results at various loading rates. Modelling of drop tests of the RPC containers from various heights are then presented. The good correlation between experimental and numerical results, in terms of the evaluation of the critical height, the orientation and the position of the cracks, demonstrate the suitability of the model for engineering purposes, speially for initial design studies
6
Madzivire, Godfrey. "Chemistry and speciation of potentially toxic and radioactive elements during mine water treatment". University of the Western Cape, 2012. http://hdl.handle.net/11394/4585.
Abstract (sommario):
Philosophiae Doctor - PhDMine water poses a serious environmental challenge and contains elements such as Fe, Al, and Mn in potentially toxic concentrations. The major anion in mine water is sulphate. The complexity and diversity of mine water composition makes its treatment very expensive, and there is no “one-fits-all” treatment option available for mine water. Active treatment of mine water produces water with good quality but the processes are not sustainable because of the costs. Previous studies have shown that acid mine drainage can be treated with coal FA to produce better quality water. The use of coal FA, a waste material from coal fired power station and mine water would go a long way in achievement of sustainable treatment of mine water as per previous studies. In this study mine water and coal FA were characterized to determine their physiochemical properties. This study linked the modelling results obtained by using the Geochemist’s workbench (GWB) software to the results obtained during the actual treatment of Matla mine water and Rand Uranium mine water using coal FA and lime. The chemistry involved when Matla mine water and Rand Uranium mine water were treated with flocculants was also investigated. Lastly the chemistry and kinetics involved was investigated when mine water was treated with various ameliorants such as Matla coal FA, lime and/or Al(OH)3 using jet loop mixing or overhead stirring. Mine water from Matla coal mine had a pH of 8 and therefore was classified as neutral mine drainage (NMD). Rand Uranium mine water had a pH of less than 3 and therefore was classified as acid mine drainage (AMD). The concentration of sulphate, Na, Ca, Mg, B, Hg, Se and Cd ions in Matla mine water was 1475, 956, 70, 40, 15, 2.43, 1.12 and 0.005 mg/L respectively. The concentration of sulphate, Fe, Ca, Mn, Mg, Al, B, Cr, Pb, U, Cd, Se and As ions in Rand Uranium mine water was 4126, 896, 376, 282, 155, 27, 5.43, 3.15, 0.51, 0.29, 0.007, 0.06 and 0.006 mg/L respectively . These concentrations were above the target water quality range (TWQR) for potable water set by the Department of Water Affairs (DWA) and World Health Organization (WHO). The gross alpha radioactivity was 6.01 Bq/L and gross beta radioactivity was 6.05 Bq/L in Rand Uranium mine water.
7
Huang, Yi-Ming. "U-Th-Pb fractionation in selected carbonate and silicate systems". Thesis, Open University, 1995. http://oro.open.ac.uk/57547/.
Abstract (sommario):
V-Th-Pb fractionation trends, and the associated variations in Pb-isotopes, provide important constraints on the nature, and age, of a wide range of geological processes. This thesis presents three detailed case studies from a carbonatite intrusive complex, lower crustal granulite xenoliths, and young volcanic rocks which represent a range of processes that fractionate V, Th and Pb. New major, trace element and Sr, Nd and Pb isotope results are presented for carbonatites and pyroxenites from the 130 Ma old Jacupiranga complex in southern Brazil. The data preclude simple models in which the Sr-Nd and Sr-Pb isotope arrays are the result of crustal contamination processes, or liquid immiscibility between the carbonatites and magmas similar to those from which the pyroxenites crystallised. The initial Sr, Nd and Pb isotope ratios in the Jacupiranga complex are similar to those in the Parana high-Ti basalts and to the oceanic basalts of the Walvis Ridge and Tristan da Cunha, and were apparently inherited from the mantle source regions associated with incipient magmatism of the Tristan da Cunha hotspot and the opening of the South Atlantic. Most carbonatites have high V/Pb and low Rb/Sr ratios and infiltration and/ or metasomatism by such melts is one process that may be responsible for the negative correlation of U/Pb and Rb/Sr inferred for the source of certain oceanic basalts such as Tristan da Cunha. Correlations between trace and major elements in mostly mafic granulite xenoliths from southern Africa probably result from magmatic processes such as fractional crystallisation and crystal accumulation. From Pb and Nd isotope systematics it can be inferred that the northern Lesotho xenoliths are Proterozoic in age, whereas Cape province xenoliths appear to have been fonned in the Archaean and to have had their Nd isotopes reset in the Proterozoic. Most Pb isotope ratios from the granulites xenoliths are unradiogenic relative to the Geochron, which indicates relatively low V /Pb ratios in the later parts of their histories. The correlation between Pb isotope ratios and K2O/A12O3 in the granulites from Markt is considered to reflect magmatic control of the V /Pb fractionation. The Archaean, and some of the younger mantle derived rocks on the Kaapvaal craton, plot on similar Pb isotope trends. It is argued that segments of the crust and uppennost mantle beneath southern Africa stabilised together in the Archaean, and that both were remobilised in subsequent magmatic and orogenic events. Volcanic rocks in the Northland-Auckland peninsula, New Zealand, range from silica-undersaturated basanites to tholeiites and andesites. Although all the volcanic fields are in intraplate settings, two types of mantle source enrichment can be recognised. One is subduction-related and characterised by high Sr and low Nd isotope ratios and negative Nb anomalies. The other type has geochemical features characteristic of intraplate enriched mantle sources with Sr and Nd isotope ratios and Nb/Ba, Ba/La, similar to HIMV OIB, which has been attributed to the deep recycling of oceanic crust. The differences in Pb isotopes between the two mantle sources, i.e. higher /lB/4 and 7/4, but lower 206Pb/204Pb in the subduction-related material than in the inferred HIMU source, indicate that V/Pb in shallow recycled crustal material tend to be lower than in the deeper recycled material. These case studies confirm that (i) metasomatism by small degree melts can have significant effects on mantle trace element characteristics, (ii) the lower crust is a relatively low 11 environment and crystal accumulation may be an important mechanism in the fractionation of Th and U from Pb, cUld (iii) incorporation of recycled crustal material at different levels can result in different V-Th-Pb fractionation and so, with time, different Pb isotope ratios.
8
Belline, Jean de Brito. "Sorção de lantanídeos em meio aquoso visando ao estudo de rejeitos nucleares". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/15957.
Abstract (sommario):
O problema de rejeitos radioativos é uma preocupação de âmbito mundial, uma vez que não há, ainda, um local definido para a construção de um repositório para rejeitos radioativos de alto nível. Uma das etapas preliminares para a escolha do local mais apropriado é o estudo geológico associado a estudos experimentais de adsorção das espécies químicas envolvidas nos processo. Neste trabalho foi utilizado uma amostra de rocha basáltica, da região sul da Formação Serra Geral, coletada em Frederico Westphalen (RS), que servirá como candidata à rocha hospedeira para locação de rejeitos radioativos. Foram realizados dois experimentos, a saber: "Batch Test" e percolação, ambos sob pressão atmosférica, à temperatura ambiente de 25°C, com a finalidade de estudar a capacidade de sorção dos elementos terras raras - ETR. Os ETR são utilizados neste trabalho em função de sua analogia com os actinídeos, visando a investigar o comportamento geoquímico e a especiações dos mesmos em águas naturais, buscando a possibilidade de armazenamento geológico de rejeitos radioativos, uma vez que a adsorção dos ETR depende de variáveis do ambiente como pH, força iônica, temperatura e presença de ligantes, como carbonatos e constituintes de superfícies dos minerais. Foi realizado experimento de percolação dos ETR, a 100ppb, no basalto (com granulometria 80 mesh) em soluções com força iônica I= 0,025 M e I=0,5 M de NaCl. O pH foi controlado em uma faixa de 5,6 a 7,6 com adição de HNO3. As concentrações foram analisadas por ICP-MS. O "Batch Test" é uma eficiente forma de se obter isotermas de sorção/dessorção, além de valores da razão entre as distribuições sólido/solução e estimar a solubilidade. O experimento de percolação, foi realizado sob pH controlado em torno de 6, e permitiu verificar a "preferência" dos ETR pesados em relação aos ETR leves.The problem of radioactive wastes is a concern of world-wide scope, a time that does not still have a defined local for the construction of a repository for radioactive wastes of high level. One of the preliminary stages for the choice of the place more appropriate is the geologic study associated to the experimental studies of adsorprtion of the involved chemical species in the process. In this work, a sample of basaltic rock was used, of the South Region of the Formation Serra Geral, collected in Frederico Westphalen Town (RS), that it will be probably a candidate to the rock hostess for location of radioactive wastes. Two experiments have been carried out through, namely: "Test Batch" and Percolating, both under atmospheric pressure, at the ambient temperature of 25°C, with the purpose to study the capacity of sorption of the rare earth elements - REE. The REE are used in this work in function of its analogy with the actinídes, aiming at to investigate the chemistry behavior and the speciations of the same in natural waters, searching the possibility of geologic storage of radioactive wastes, a time that the adsorption of the REE depends on variables of the environment as pH, ionic strengh, temperature and presence of ligants, as carbonates and constituent of surfaces of minerals. Experiment of percolating of the REE was carried through, 100ppb, in the basalt (with 80 mesh) in solutions with ionic strengh I= 0,025 M and I=0,5 M of NaCl. pH was controlled in a range of 5,6 the 7,6 with HNO3 addition. The concentrations were analyzed by ICP-MS. The "Batch Test" is an efficient form of studing sorption/dessorption isotherms, beyond values of the reason between the distributions solid/solution and estimation of the solubility. The percolating experiment, was carried through under pH controlled around 6, and allowed to verify the behaviour of heavy REE in comparison with the light REE.
9
Murry, Maisha M. "Dissolution and Sequential Extraction of select radioactive and stable elements in soil and lunar regolith simulants". University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1583999571140163.
10
Karavan, Maria. "Phosphorylated calixarenes for the recognition of f-elements". Strasbourg, 2009. http://www.theses.fr/2009STRA6207.
Abstract (sommario):
Le traitement des déchets radioactifs issus de la production d’énergie nucléaire constitue un des problèmes industriels les plus importants. Ce travail se situe en amont de ces applications et vise à acquérir des données fondamentales pour la séparation des radionucléides à vie longue des déchets radioactifs liquides en utilisant trois familles de nouveaux composés macrocycliques polyfonctionnels basés sur des calix[n]arènes : des dérivés substitués par des oxydes de phosphine, soit au bord large, soit au bord étroit, et des dérivés substitués au bord large par des groupements diphosphonates. Deux approches ont été utilisées pour évaluer les interactions entre les ions La3+, Eu3+, Yb3+, Am3+, Th4+, Pu4+, UO22+ et TcO4- et les nouveaux ligands : (i) l’extraction des sels métalliques, de solutions aqueuses d’acide nitrique vers des solutions organiques (m-nitrobenzotrifluorure, dichlorométhane); (ii) la complexation dans le méthanol et l’acétonitrile en utilisant la spectrophotométrie d’absorption dans l’UV et la microcalorimétrie isotherme de titrage. Cette dernière technique s’est révélée particulièrement utile pour la détermination des stœchiométries des complexes et a permis leur caractérisation thermodynamique complète (DG, DH et DS). Les résultats ont montré la grande affinité de ces composés envers les cations Eu3+, Am3+ et UO22+. L’influence de l’acidité de la phase aqueuse sur les coefficients de distribution et l’influence de caractéristiques structurales des ligands (nature des groupes fonctionnels et des substituants, degré de condensation) sur les paramètres thermodynamiques de complexation ont été examinées. La remarquable solubilité dans l’eau des dérivés substitués au bord large par des oxydes de phosphine a permis le développement d’une nouvelle méthode de séparation des actinides par extraction micellaire, qui a été testée sur des déchets réelsThe treatment of radioactive wastes issuing from nuclear power is one of the most important industrial problems. This work aims at acquiring basis data for the separation of long-lived radionuclides by using three families of new polyfunctional macrocyclic compounds based on calix[n]arenes: derivatives substituted with phosphine oxides either at the wide or the narrow rims, and derivatives substituted at the wide rim with diphosphonate groups. Two approaches were used to evaluate the interactions between La3+, Eu3+, Yb3+, Am3+, Th4+, Pu4+, UO22+ and TcO4- ions and the new ligands: (i) extraction of the metal salts, from aqueous solutions of nitric acid into an organic solution (m-nitrobenzotrifluorure, dichloromethane); (ii) complexation in methanol and acetonitrile using UV absorption spectrophotometry and isothermal titration microcalorimetry. The latter technique revealed to be particularly useful for the determination of the complex stoichiometry and allowed their full thermodynamic characterization (DG, DH and DS). The results show the high affinity of these compounds for Eu3+, Am3+ and UO22+ cations. The influence of the acidity of the aqueous phase on the distribution coefficients and the influence of some structural features of the ligands (nature of the functional groups and substituents, condensation degree) on the thermodynamic parameters have been examined. The remarkable water solubility of the wide rim phosphine oxide calix[4]arenes allowed the development of a new actinide separation method based on micellar extraction, which was tested on real wastes
Libri sul tema "Radioactif element":
1
Tom, Jackson. Radioactive elements. New York: Marshall Cavendish Benchmark, 2005.
2
United States. Environmental Protection Agency. Office of Radiation Programs e United States. Environmental Protection Agency. Office of Air and Radiation, a cura di. Transuranium elements. Washington, DC: Office of Radiation Programs, U.S. Environmental Protection Agency, 1997.
3
United States. Environmental Protection Agency. Office of Radiation Programs. e United States. Environmental Protection Agency. Office of Air and Radiation., a cura di. Transuranium elements. Washington, DC: Office of Radiation Programs, U.S. Environmental Protection Agency, 1997.
4
United States. Environmental Protection Agency. Office of Radiation Programs. e United States. Environmental Protection Agency. Office of Air and Radiation., a cura di. Transuranium elements. Washington, DC: Office of Radiation Programs, U.S. Environmental Protection Agency, 1997.
5
Matthias, Schädel, a cura di. The chemistry of superheavy elements. Dordrecht: Kluwer Academic Publishers, 2003.
6
R, Chitnis R., e Bhabha Atomic Research Centre, a cura di. Partitioning of actinides from high active waste solution of purex origin: Counter-current extraction studies using TBP and CMPO. Mumbai: Bhabha Atomic Research Centre, 2000.
7
Board, M. P. UDEC (Universal Distinct Element Code) version ICG1.5. Washington, DC: Division of High-Level Waste Management, Office of Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, 1989.
8
Nilaya, J. Padma. Laser assisted decontamination of nuclear fuel elements. Mumbai: Bhabha Atomic Research Centre, 2010.
9
Board, Mark. UDEC (Universal Distinct Element Code) version ICG1.5. Washington, D.C: Division of High-Level Waste Management, Office of Nuclear Material Safety and Safeguards, U.S. Nuclear Regulatory Commission, 1989.
10
Fajans, Kasimir. Radioelements and isotopes: Chemical forces and optical properties of substances. Mineola, N.Y: Dover Publications, 2005.
Capitoli di libri sul tema "Radioactif element":
1
Singhal, Pallavi. "Optical Materials for Sensing Radioactive Elements". In Handbook of Materials Science, Volume 1, 159–82. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-7145-9_6.
2
Wang, Yajie, Lufeng Wang, Chuanjiang Dong, Li Li, Mengqi Tang, Weizhong Sun e Yao Wu. "Evaluation of Uncertainty for Determination of Trace Uranium in Biology by Laser Fluorescence Method". In Springer Proceedings in Physics, 549–66. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1023-6_48.
Abstract (sommario):
AbstractLarge amounts of uranium-containing radioactive waste are generated in reactor operation and in the research and manufacture of nuclear fuel elements. At present, there are various uranium enrichment and separation methods such as reduction precipitation method, ion exchange method, solvent extraction method, membrane filtration method, adsorption method, and microorganism method to treat the uranium-containing radioactive waste generated in the related processes of nuclear facilities. However, the airborne effluent or liquid effluent discharged after treatment may still contain radioactive uranium. It is well known that uranium is a radioactive heavy metal element, and its radioactive and chemical toxicity cannot be ignored. Uranium in the environment enters the human body through the food route, and its long half-life can make the human body suffer from continuous radioactive internal radiation damage. As an environmental medium, organisms are closely related to the entry of uranium into the human body through food. Therefore, it is of great significance to carry out accurate measurement of uranium content in environmental-grade biological samples around nuclear facilities, however, complete and accurate measurement results include measurement data and uncertainty. Laser fluorescence method is a method for rapid analysis of uranium content in environmental samples. It has the advantages of high sensitivity, simple sample pretreatment, and wide measurement range, which has been widely used in nuclear industry, environmental monitoring and scientific research. At present, there is a lack of relevant reports on the uncertainty of the measurement of total uranium content in environmental-grade biological samples by laser fluorescence method. It is of great significance to accurately measure the uranium content in biological samples by evaluating the uncertainty of this method. In this paper, the WGJ-III trace uranium analyzer was used to analyze the uncertainty source of total uranium in environmental-grade biological samples by laser fluorescence method. The uncertainty measurement model was established, the uncertainty components were quantified, and the expanded uncertainty of the measurement of total uranium content in environmental biological samples was calculated. The evaluation results showed that the expanded uncertainty of a 0.05 g environmental biological sample is 10.8% (k = 2) without dilution, and the dominant uncertainty component is derived from the measurement uncertainty of sample fluorescence counting.
3
Majumder, Madhumita, e Anjalika Roy. "Application of Microbes in Leaching Rare Earth Elements and Radioactive Elements". In Biohydrometallurgical Processes, 108–29. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9781003451457-6.
4
Schell, W. R., M. B. Goldman e I. Linkov. "Radioactive and Trace Elements in the Ural Mountains". In Air Pollution in the Ural Mountains, 441–44. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5208-2_44.
5
Nikolaev, Anton, Olga Frank-Kamenetskaya, Michael Zuykov e Elena Rosseeva. "Radioactive Elements in Bone Tissue From Freshwater Fish". In Proceedings of the 10th International Congress for Applied Mineralogy (ICAM), 471–78. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-27682-8_56.
6
Attendorn, H. G., e R. N. C. Bowen. "Nucleosynthesis: Fons et origo of the chemical elements in the universe and on Earth". In Radioactive and Stable Isotope Geology, 30–55. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5840-4_2.
7
Wu, Xuan, Wenyu Li, Li Lin, Yi Liang, Jiaheng Zhang, Wenlu Gu, Jiheng Fan, EnWei Shen e KouHong Xiong. "Thermodynamic Equilibrium Analysis of Steam Reforming Reaction of Radioactive Waste Oil". In Springer Proceedings in Physics, 1127–33. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1023-6_97.
Abstract (sommario):
AbstractAt present, there are much radioactive waste oil temporarily stored in nuclear fuel processing plants, nuclear industry research institutes and operating nuclear power plants in China, which brings great storage pressure and safety risks to the operating nuclear facilities. In this paper, the components analysis of 40# waste oil used in nuclear facilities was carried out, and the elemental composition and chemical composition of the waste oil were obtained. The analysis showed that the main elements in the waste oil were C and H, and the main chemical components were alkanes, alkenes, aromatic hydrocarbons and alcohols with carbon chain length of 10–40. Using Aspen Plus software, the process flow model of waste oil’s steam reforming treatment was established. Based on the components analysis results of the waste oil, organic mixtures such as ethanol, ethane and propane were selected as the model components, and the element composition close to waste oil was obtained by adjusting the proportion of each component. The mixture was used as the source input of Aspen Plus to achieve good simulation results. The experimental results obtained under Pt catalyst at 400 ℃ were in good agreement with the simulation results, which confirmed the validity of the model. The thermodynamic equilibrium analysis of waste oil steam reforming reaction was carried out by using the verified model. The influence of reaction temperature (350–1150 ℃), pressure (0.01–100bar) and water to carbon ratio (0.01–100) on reforming reaction and off gas components in balanced state was studied. The conclusions are as follows: (1) The steam reforming reaction of waste oil has no obvious inhibition when the reaction pressure is less than 1bar, so the reforming reaction should be carried out under the condition of negative pressure less than 1bar; (2) The temperature should be maintained above 750 ℃ to ensure the complete steam reforming reaction; (3) Carbon deposition can be completely eliminated when the water/carbon ratio is higher than 1, and when the water/carbon ratio is higher than 10, the product components do not change with the water/carbon ratio.
8
Joshi, S. R., e A. G. Bobba. "Finite Element Modelling of Transport of Radium-226 and Uranium from Port Granby Radioactive Waste Management Site to Lake Ontario". In Reliability of Radioactive Transfer Models, 193–200. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-1369-1_22.
9
Hofmann, B., J. P. L. Dearlove, M. Ivanovich, D. A. Lever, D. C. Green, P. Baertschi e Tj Peters. "Evidence of Fossil and Recent Diffusive Element Migration in Reduction Haloes from Permian Red-Beds of Northern Switzerland". In Natural Analogues in Radioactive Waste Disposal, 217–38. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3465-8_21.
10
Sato, C., S. Kazama, A. Sakamoto e K. Hirayanagi. "Behavior of Radioactive Elements (Uranium and Thorium) in Bayer Process". In Essential Readings in Light Metals, 191–97. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48176-0_25.
Atti di convegni sul tema "Radioactif element":
1
Gopka, Vira. "Radioactive elements in stellar atmospheres". In ORIGIN OF MATTER AND EVOLUTION OF GALAXIES: International Symposium on Origin of Matter and Evolution of Galaxies 2005: New Horizon of Nuclear Astrophysics and Cosmology. AIP, 2006. http://dx.doi.org/10.1063/1.2234435.
2
Ge, Yongjun, Yishan Lin, Honghu Xie e Jinchun Yang. "Design and Development of Intelligent Replacement Robot for Radioactive Spent Filter Element in NPP and Its Performance Validation". In 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-93482.
Abstract (sommario):
Abstract During the operation of a nuclear power plant, many main systems will generate variety of radioactive spent filter elements. These filter elements are main solid waste which need to be replaced regularly to keep safety of these systems. Because these filter elements have a certain level of radioactivity, the replacement operation has a higher risk. Therefore, according to the national and nuclear power plant radioactive waste regulations, it is necessary to ensure the safe and reliable operation of the radiation protection, make sure that operator and facilities are protected from radiation exposure or minimized. Based on the analysis of the filter element replacement process and equipment of domestic nuclear power units in service, combined with the requirements of newel construction of intelligent nuclear power plants, it is necessary to propose a radioactive spent filter element intelligent replacement ROBOT program. This paper discusses the design scheme of a new intelligent replacement robot for radioactive spent filter elements, and key issues involving fully automatic replacement technology for radioactive filter elements, such as filter layout and filter element replacement process optimization, robot grabbing actuator design, robot positioning mechanism design and accuracy guarantee, etc. have been systematically studied. A set of robot systems with intelligent replacement of radioactive irrationality have been developed. The test has been verified and the technical conditions for implementation in NPP have been met.
3
Dodona, A., e M. Bytyci. "The Radon radioactive element and its contamination". In 5th Congress of Balkan Geophysical Society. European Association of Geoscientists & Engineers, 2009. http://dx.doi.org/10.3997/2214-4609-pdb.126.6268.
4
Rudolph, Dirk. "Superheavy Element Studies with TASCA at GSI: Spectroscopy of Element 115 Decay Chains". In Proceedings of the Conference on Advances in Radioactive Isotope Science (ARIS2014). Journal of the Physical Society of Japan, 2015. http://dx.doi.org/10.7566/jpscp.6.010026.
5
Nie, Rui, Yu Wang, Feng Xie, Shan Qing e Jianzhu Cao. "Investigation of the Fuel Element Damage Monitoring Technology in HTGRs and PWRs". In 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-88883.
Abstract (sommario):
Abstract Understanding the performance of fuel elements, particularly defective ones, in the reactor core quickly and accurately is essential as most radioactive nuclides are produced in the fuel elements and released into the primary circuit. Radioactivity in the primary circuit may result in potential radiation hazards to the maintenance workers and the environment near the nuclear power plant. Therefore, fuel element damage monitoring technology has received wide attention in the field of nuclear fission reactors. Few reviews focus on fuel element damage monitoring technology to facilitate the development of high-temperature gas-cooled reactors (HTGRs). In this study, we investigated the state of fuel element damage monitoring technology in HTGRs and pressurized water reactors (PWRs), summarized their characteristics and parameters, and compared their advantages and disadvantages. The radioactive source terms in HTGRs and PWRs were listed, and the typical nuclides in the primary circuit adopted for the fuel element damage monitoring were illustrated. This study can provide a good reference for developing fuel element damage monitoring technology in HTGRs in the future.
6
Ammerman, Douglas J. "Benchmarking of Finite Element Codes for Radioactive Material Transportation Packages". In ASME 1996 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/imece1996-0560.
Abstract (sommario):
Abstract The increased power of computers and computer codes makes the use of nonlinear dynamic finite element analyses attractive for use as a tool used in the design and certification of radioactive material transportation packages. For this analysis technique to be acceptable it must be demonstrated the technique has the ability to accurately capture the response of the packages to accident environments required by the regulations. The best method of demonstrating this ability is via a series of benchmark analyses. In this paper three benchmark problems involving significant inelastic deformations will be discussed. One of the problems has been analyzed using many different finite element codes. The other two problems involve comparison of finite element calculations to the results from physical tests. The ability of the finite element method to accurately capture the response in these three problems indicates the method should be acceptable for radioactive material transportation package design and certification.
7
Waggoner, Charles A., Michael S. Parsons e Paxton K. Giffin. "Evaluating Performance of High Efficiency Mist Eliminators". In ASME 2013 15th International Conference on Environmental Remediation and Radioactive Waste Management. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icem2013-96307.
Abstract (sommario):
Processing liquid wastes frequently generates off gas streams with high humidity and liquid aerosols. Droplet laden air streams can be produced from tank mixing or sparging and processes such as reforming or evaporative volume reduction. Unfortunately these wet air streams represent a genuine threat to HEPA filters. High efficiency mist eliminators (HEME) are one option for removal of liquid aerosols with high dissolved or suspended solids content. HEMEs have been used extensively in industrial applications, however they have not seen widespread use in the nuclear industry. Filtering efficiency data along with loading curves are not readily available for these units and data that exist are not easily translated to operational parameters in liquid waste treatment plants. A specialized test stand has been developed to evaluate the performance of HEME elements under use conditions of a US DOE facility. HEME elements were tested at three volumetric flow rates using aerosols produced from an iron-rich waste surrogate. The challenge aerosol included submicron particles produced from Laskin nozzles and super micron particles produced from a hollow cone spray nozzle. Test conditions included ambient temperature and relative humidities greater than 95%. Data collected during testing HEME elements from three different manufacturers included volumetric flow rate, differential temperature across the filter housing, downstream relative humidity, and differential pressure (dP) across the filter element. Filter challenge was discontinued at three intermediate dPs and the filter to allow determining filter efficiency using dioctyl phthalate and then with dry surrogate aerosols. Filtering efficiencies of the clean HEME, the clean HEME loaded with water, and the HEME at maximum dP were also collected using the two test aerosols. Results of the testing included differential pressure vs. time loading curves for the nine elements tested along with the mass of moisture and solid material on each element at final dP. Plots of overall filtering efficiencies for DOP (spherical aerosol) and dry surrogate (aspherical aerosols) at specified dPs were computed for each filter. Filtering efficiencies were determined as a function of particle size. Curves were also generated showing the most penetrating particle size as a function of dP. A preliminary set of tests was conducted to evaluate spray location, duration, pressure, and wash volume for in-place cleaning the interior surface (reducing dP) of the HEME element. A variety of nozzle designs were evaluated and test results demonstrated the potential to overload the HEME (saturate filter medium) resulting in very high dPs and extensive drain times. At least one combination of spray nozzle design, spray location on the surface of the element, and spray time/pressure was successful in achieving extension of operational life.
8
Meng, Dongyuan, Shutang Sun, Hongchao Sun e Guoqiang Li. "Finite Element Method for Thermal Design of Radioactive Material Transport Packages". In 2020 International Conference on Nuclear Engineering collocated with the ASME 2020 Power Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/icone2020-16115.
Abstract (sommario):
Abstract In this paper, a simplified typical radioactive material transport container model is used to change the thickness of the container insulation layer and the thickness of the heat sink respectively. The finite element method is used to simulate the heat transfer, and a quantitative optimization of the heat transfer performance of the radioactive material transport container is given.
9
Dongyuan, Meng, Wang Renze, Zhang Jiangang, Li Guoqiang, Zhuang Dajie, Sun Hongchao, Wang Xuexin e Sun Shutang. "The Finite Element Method for Retention System of Radioactive Material Transport Package". In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-66853.
Abstract (sommario):
According to IAEA “Advisory Material for the IAEA Regulations for the Safe Transport of Radioactive Material”, the retention of radioactive material transport package need to be paid attention. Finite Element (FE) method is an efficient way to verify the retention system. Two typical kinds of retention systems are simulated by FE. Two important aspects, mesh density and contact model are discussed for their influence of the calculation time and calculation accuracy. The method could be promoted to other aspects in radioactive material transport.
10
Sayin, Nurdan. "THE HEAT PRODUCTION BY RADIOACTIVE ELEMENTS IN THE MARMARA REGION". In SGEM2011 11th International Multidisciplinary Scientific GeoConference and EXPO. Stef92 Technology, 2011. http://dx.doi.org/10.5593/sgem2011/s06.126.
Rapporti di organizzazioni sul tema "Radioactif element":
1
P. Bernot. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS. Office of Scientific and Technical Information (OSTI), luglio 2005. http://dx.doi.org/10.2172/883412.
2
Chen, Y., E. R. Thomas, F. J. Pearson, P. L. Cloke, T. L. Steinborn e P. V. Brady. Dissolved Concentration Limits of Radioactive Elements. Office of Scientific and Technical Information (OSTI), giugno 2003. http://dx.doi.org/10.2172/836527.
3
NA. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS. Office of Scientific and Technical Information (OSTI), novembre 2004. http://dx.doi.org/10.2172/859259.
4
Ammerman, D. J. Benchmarking of finite element codes for radioactive material transportation packages. Office of Scientific and Technical Information (OSTI), ottobre 1996. http://dx.doi.org/10.2172/402278.
5
Alokhina, Tetiana, e Vadym Gudzenko. Distribution of radionuclides in modern sediments of the rivers flowing into the Dnieper-Bug Estuary. EDP Sciences, 2021. http://dx.doi.org/10.31812/123456789/4617.
Abstract (sommario):
The article presents the results of large-scale studies of the content and distribution of natural and man-made radionuclides in the sediments of the rivers flowing into the Dnieper-Bug estuary. The article also presents the results of the granulometric analysis of the surveyed water bodies. The data about natural radioactive elements in the sediments rivers flowing into the Dnieper-Bug estuary obtained in this research are demonstrated moderate specific activity, which, however, clearly correlates with the granulometric composition of sediments. The 137Cs determined by us is contained in the sediments of all studied water bodies and the places of it greatest concentration coincide with the areas in which the sediment is represented mainly by the pelitic fraction. The data obtained in this research can serve as a baseline data in natural radionuclides concentration in sediments rivers flowing into the Dnieper-Bug estuary. The obtained data can also be used for further monitoring of the specific activity of man-made radionuclides, in particular 137Cs.
6
Delegard, C. H., V. F. Peretrukhin, V. P. Shilov e A. K. Pikaev. Alkaline chemistry of transuranium elements and technetium and the treatment of alkaline radioactive wastes. Office of Scientific and Technical Information (OSTI), maggio 1995. http://dx.doi.org/10.2172/92064.
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Peters, T., F. Fondeur e S. Fink. RESULTS FROM ANALYSIS OF THE FIRST AND SECOND STRIP EFFLUENT COALESCER ELEMENTS FROM RADIOACTIVE OPERATIONS OF THE MODULAR CAUSTIC-SIDE SOLVENT EXTRACTION UNIT. Office of Scientific and Technical Information (OSTI), giugno 2011. http://dx.doi.org/10.2172/1029960.