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[en] Autoradiographic analysis which has a radio-sensitive film or screen is introduced. This method can analyze migration behavior of a certain specific material in macro-scale and/or micro-scale quantitatively. It is widely used in the field of biology, material science, environmental contamination. As a specific application field, migration phenomena of radioactive nuclides onto geomedia, which are carrying in KAERI, are selected and explained in detail on working procedures and using manuals
[en] This abstract is about Efficiency of using isotope methods and radiation biogeocenology for determination of migration and spatial distribution of radionuclides
[ru]Etot abstract ob effektivnosti primeneniya izotopnikh metodov i radiatsionnoy biogeotsenologii v opredelenii migratsii i prostranstvennogo paspredeleniya radionuclidov
[en] In Spain, the waste management options include either the possibility of a final storage in a deep geological repository (DGR) or the centralized temporal surface disposal (CTS). DGRs are based in a multi-barrier concept with the geological barrier and including the vitrified waste, the metal containers and engineered barriers such as compacted bentonite and cement-based materials. On the other hand, CTS mainly considers concrete and cement to confine the metal canisters containing the waste. Radionuclide migration will mainly take place by the existence of chemical concentration gradients being thus diffusion the main transport mechanism or by the existence of hydraulic gradients due to the existence of water-conductive fractures. Radionuclide sorption/retention on the materials composing the natural and engineered barriers is the fundamental process controlling contaminant migration. The evaluation of sorption parameters and the understanding of the different mechanisms leading to radionuclide retention are very important issues. The study of diffusion processes is very relevant as well. This paper describes the main experimental methodologies applied to analyse radionuclide transport in the different barriers of radioactive repositories. Particularly we focused on obtaining of retention parameters as distribution coefficients, kd, or retardation factors, Rf, and diffusion coefficients of radionuclides. (Author) 6 refs.
[en] To solve the atomic problem, including the creation of an atomic weapon, one must embark on an intensive exploration and mining of radioactive raw materials, first among which uranium, together with other materials and metals. The acquisition of all these materials has thus been accompanied by the creation of a great deal of production and storage wastes and other refuse from plants, leading to many problems of protecting the environment from radioactive and other hazardous metals and materials. And so, as a result of the extensive mining and processing of radioactive and other raw materials that had been necessary for the atomic industry, in locations like Kara-Balty, Mailuu-Suu, Kavak, Kadamzhay and other places, a series of radioactive and hazardous tailings and dumps has been generated in the Kyrgyz Republic. The toxic ingredients from the dumps migrate and mix together with the ground waters that leach the tailings. However, how these waters migrate both in space and time have not been sufficiently studied; and, so, in general, we cannot forecast the propagation of these hazards. In the usual estimation of the scale of migration from uranium plants, only the total uranium content in the ground water is used. But this does not show natural or technogenic components; and it is obvious that the danger from the plants need only be characterized by the technogenic components. To solve this problem, one can employ the phenomenon where there is a natural separation in the fraction of 234U and 238U present in nature and as a result of technological processes. The essence of this understanding is that, as uranium transitions from solid form into a liquid, such as its dissolution in ground water, it undergoes isotope enrichment, i.e. hydrogenic uranium is enriched with 234U compared to 238U.The essence of this understanding is that, as uranium transitions from solid form into a liquid, such as its dissolution in ground water, it undergoes isotope enrichment, i.e. hydrogenic uranium is enriched with 234U compared to 238U. In the technological cycle, during the extraction of the uranium element by dissolution from uranium ore (or from any other mineral raw material), the proportion between the uranium isotopes does not change. That is, the technological process does not lead to the enhancement of one uranium isotope over another. So, there is some real possibility that, by measuring the magnitude of γ = 234U/238U in various environments, one can discern technogenic uranium (where γ = 0) from the uranium leached into ground waters from dumps and tailings (where γ > 0). In this work we attempted to utilize this effect for the purpose of defining the technogenic fraction of uranium in the waters of the Naryn and Mailuu-Suu rivers. To measure uranium content CU and isotopic concentration ratio γ, samples were taken from these rivers at locations shown in Figure 1. The sampling was performed within the framework of Project Navruz-an international program of collaboration for the trans-boundary monitoring of rivers, sponsored by the Republics of Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan and the United States of America. Further information about this project can be found on this web site: http://www.cmc.sandia.gov/Central/centralasia.html
[en] The generation of gases and possible development and migration of a gas phase at depth in groundwater-saturated, fractured rock has become an important aspect of assessing the performance and safety of radioactive waste disposal sites. To study gas-phase migration in this environment, helium gas was injected at constant pressure through an access borehole into an inclined fracture zone at a depth of about 40 m, in the granitic Lac du Bonnet Batholith, southeastern Manitoba, Canada. The gas flow rate, arrival time and pattern of distribution of gas at the surface were monitored by soil gas surveys. Gas flow rate increased from 5 to 20 1 min-1 over the 11-day period of the test indicating removal of water from the flow paths. Breakthrough of injected gas at the surface was detected within 2 days. Two areas of high concentrations of gas discharge were observed within 40 m of the injection borehole, indicating gas transport through near-vertical fractures. A larger area of trace He concentrations was detected 200 m away indicating transport along the fracture zone. The field results were compared with predictions of a simple analytical model derived from Braester and Thunvik (1983). Good agreement was found when the influence of fracturing in the bedrock and a low-permeability overburden and 'excess porosity' due to non-uniformity of fracture apertures were included in the model. The model was then used to estimate and map the relative hydraulic conductivities of individual gas flow paths in the fractured rock. (author)
[en] Vertical migration of plutonium in soils at the Waste Isolation Pilot Plant (WIPP) and the Rocky Flats Environmental Technology Site (RFETS) was evaluated based on observed 134Cs migration in soil column experiments. After applying 134Cs-labeled soil particles to the surfaces of large, undisturbed soil cores collected from each site, resulting soil columns were subjected to experimental cycles of irrigation plus drying (treatment columns) or to cycles of irrigation only (control columns). Mean losses of 134Cs inventory from soil surfaces were 3.1 ± 0.6% cycle-1 and 0.7 ± 0.6% cycle-1 respectively for RFETS treatment and control columns. WIPP columns had mean respective losses of 1.3 ± 1.2% cycle-1 and 0.5 ± 0.2% cycle-1. Bulk transport of labeled soil particles through soil cracks was an important process in RFETS soils, accounting for 64-86% of total 134Cs migration. Colloidal transport processes governed migration in WIPP soils
[en] The classification of geochemical structures of landscapes has been developed on the base of regularities of the variation of chemical element concentration within geochemical katen and a nature of their accumulation in different soil layers. Main factors of forming structure and its spatial allocation under conditions of Belarus have been identified. (Authors)
[en] A particle tracking scheme was developed in order to model radionuclide transport through a tortuous flow field in a rock fracture. The particle tracking method may be used effectively in a heterogeneous flow field such as rock fracture. The parallel plate representation of the single fracture fails to recognize the spatial heterogeneity in the fracture aperture and thus seems inadequate in describing fluid movement through a real fracture. The heterogeneous flow field was modeled by a variable aperture channel model after characterizing aperture distribution by a hydraulic test. To support the validation of radionuclide transport models, a radionuclide migration experiment was performed in a natural fracture of granite. 3H2O and 131I are used as tracers. Simulated results were in agreement with experimental result and therefore support the validity of the transport model. Residence time distributions display multipeak curves caused by the fast arrival of solutes traveling along preferential fracture channels and by the much slower arrival of solutes following tortuous routes through the fracture. Results from the modelling of the transport of nonsorbing tracer through the fracture show that diffusion into the interconnected pore space in the rock mass has a significant effect on retardation. 12 figs., 3 tabs., 17 refs. (Author)
[en] Planetary migration poses a serious challenge to theories of planet formation. In gaseous and planetesimal disks, migration can remove planets as quickly as they form. To explore migration in a planetesimal disk, we combine analytic and numerical approaches. After deriving general analytic migration rates for isolated planets, we use N-body simulations to confirm these results for fast and slow migration modes. Migration rates scale as m-1 (for massive planets) and (1 + (eH/3)3)-1, where m is the mass of a planet and eH is the eccentricity of the background planetesimals in Hill units. When multiple planets stir the disk, our simulations yield the new result that large-scale migration ceases. Thus, growing planets do not migrate through planetesimal disks. To extend these results to migration in gaseous disks, we compare physical interactions and rates. Although migration through a gaseous disk is an important issue for the formation of gas giants, we conclude that migration has little impact on the formation of terrestrial planets.