The Experts below are selected from a list of 245487 Experts worldwide ranked by ideXlab platform
Gary A Cooke - One of the best experts on this subject based on the ideXlab platform.
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development of a carbonate crust on alkaline nuclear Waste sludge at the hanford site
Journal of Hazardous Materials, 2018Co-Authors: Jason S Page, Jacob G Reynolds, Gary A CookeAbstract:Abstract Hard crusts on aging plutonium Production Waste have hindered the remediation of the Hanford Site in southeastern Washington, USA. In this study, samples were analyzed to determine the cause of a hard crust that developed on the highly radioactive sludge during 20 years of inactivity in one of the underground tanks (tank 241-C-105). Samples recently taken from the crust were compared with those acquired before the crust appeared. X-ray diffraction and scanning electron microscopy (SEM) indicated that aluminum and uranium phases at the surface had converted from (hydr)oxides (gibbsite and clarkeite) into carbonates (dawsonite and cejkaite) and identified trona as the cementing phase, a bicarbonate that formed at the expense of thermonatrite. Since trona is more stable at lower pH values than thermonatrite, the pH of the surface decreased over time, suggesting that CO2 from the atmosphere lowered the pH. Thus, a likely cause of crust formation was the absorption of CO2 from the air, leading to a reduction of the pH and carbonation of the Waste surface. The results presented here help establish a model for how nuclear process Waste can age and can be used to aid future remediation and retrieval activities.
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development of a carbonate crust on alkaline nuclear Waste sludge at the hanford site
Journal of Hazardous Materials, 2018Co-Authors: Jason S Page, Jacob G Reynolds, Gary A CookeAbstract:Abstract Hard crusts on aging plutonium Production Waste have hindered the remediation of the Hanford Site in southeastern Washington, USA. In this study, samples were analyzed to determine the cause of a hard crust that developed on the highly radioactive sludge during 20 years of inactivity in one of the underground tanks (tank 241-C-105). Samples recently taken from the crust were compared with those acquired before the crust appeared. X-ray diffraction and scanning electron microscopy (SEM) indicated that aluminum and uranium phases at the surface had converted from (hydr)oxides (gibbsite and clarkeite) into carbonates (dawsonite and cejkaite) and identified trona as the cementing phase, a bicarbonate that formed at the expense of thermonatrite. Since trona is more stable at lower pH values than thermonatrite, the pH of the surface decreased over time, suggesting that CO2 from the atmosphere lowered the pH. Thus, a likely cause of crust formation was the absorption of CO2 from the air, leading to a reduction of the pH and carbonation of the Waste surface. The results presented here help establish a model for how nuclear process Waste can age and can be used to aid future remediation and retrieval activities.
Gérald Debenest - One of the best experts on this subject based on the ideXlab platform.
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An open-source toolbox for multiphase flow in porous media
Computer Physics Communications, 2014Co-Authors: Pierre Horgue, Cyprien Soulaine, Jacques Franc, Romain Guibert, Gérald DebenestAbstract:Multiphase flow in porous media provides a wide range of applications: from the environmental understanding (aquifer, site-pollution) to industrial process improvements (oil Production, Waste management). Modeling of such flows involve specific volume-averaged equations and therefore specific computational fluid dynamics (CFD) tools. In this work, we develop a toolbox for modeling multiphase flow in porous media with OpenFOAM®, an open-source platform for CFD. The underlying idea of this approach is to provide an easily adaptable tool that can be used in further studies to test new mathematical models or numerical methods. The package provides the most common effective properties models of the literature (relative permeability, capillary pressure) and specific boundary conditions related to porous media flows. To validate this package, a solvers based on the IMplicit Pressure Explicit Saturation (IMPES) methodare developed in the toolbox. The numerical validation is performed by comparison with analytical solutions on academic cases. Then, a satisfactory parallel efficiency of the solver is shown on a more complex configuration.
Jason S Page - One of the best experts on this subject based on the ideXlab platform.
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development of a carbonate crust on alkaline nuclear Waste sludge at the hanford site
Journal of Hazardous Materials, 2018Co-Authors: Jason S Page, Jacob G Reynolds, Gary A CookeAbstract:Abstract Hard crusts on aging plutonium Production Waste have hindered the remediation of the Hanford Site in southeastern Washington, USA. In this study, samples were analyzed to determine the cause of a hard crust that developed on the highly radioactive sludge during 20 years of inactivity in one of the underground tanks (tank 241-C-105). Samples recently taken from the crust were compared with those acquired before the crust appeared. X-ray diffraction and scanning electron microscopy (SEM) indicated that aluminum and uranium phases at the surface had converted from (hydr)oxides (gibbsite and clarkeite) into carbonates (dawsonite and cejkaite) and identified trona as the cementing phase, a bicarbonate that formed at the expense of thermonatrite. Since trona is more stable at lower pH values than thermonatrite, the pH of the surface decreased over time, suggesting that CO2 from the atmosphere lowered the pH. Thus, a likely cause of crust formation was the absorption of CO2 from the air, leading to a reduction of the pH and carbonation of the Waste surface. The results presented here help establish a model for how nuclear process Waste can age and can be used to aid future remediation and retrieval activities.
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development of a carbonate crust on alkaline nuclear Waste sludge at the hanford site
Journal of Hazardous Materials, 2018Co-Authors: Jason S Page, Jacob G Reynolds, Gary A CookeAbstract:Abstract Hard crusts on aging plutonium Production Waste have hindered the remediation of the Hanford Site in southeastern Washington, USA. In this study, samples were analyzed to determine the cause of a hard crust that developed on the highly radioactive sludge during 20 years of inactivity in one of the underground tanks (tank 241-C-105). Samples recently taken from the crust were compared with those acquired before the crust appeared. X-ray diffraction and scanning electron microscopy (SEM) indicated that aluminum and uranium phases at the surface had converted from (hydr)oxides (gibbsite and clarkeite) into carbonates (dawsonite and cejkaite) and identified trona as the cementing phase, a bicarbonate that formed at the expense of thermonatrite. Since trona is more stable at lower pH values than thermonatrite, the pH of the surface decreased over time, suggesting that CO2 from the atmosphere lowered the pH. Thus, a likely cause of crust formation was the absorption of CO2 from the air, leading to a reduction of the pH and carbonation of the Waste surface. The results presented here help establish a model for how nuclear process Waste can age and can be used to aid future remediation and retrieval activities.
Renata Boris - One of the best experts on this subject based on the ideXlab platform.
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the impact of primary sludge from paper industry on the properties of hardened cement paste and mortar
Construction and Building Materials, 2018Co-Authors: Jurgita Malaiskiene, Olga Kizinievic, Viktor Kizinievic, Renata BorisAbstract:Abstract In the paper, the impact of paper Production Waste (primary sludge, or PS) on the properties of cement pastes and mortars is discussed upon. Some specimens were formed with fine PS fraction that replaced a part of cement content in them (5%, 10%, 15%, or 20%); in other specimens, coarse fraction of sludge (2/4) was used and a part of content of fine filler (sand) was replaced by PS. The properties of mixtures, such as water content required for cement paste of normal consistence, the setting time, exothermic temperature, flow diameter and plunger penetration, were established. In addition, the properties of hardened mortar, such as its density, flexural strength and compressive strength, were established. The microstructure of hardened specimens was examined as well. It was found that PS retarded hydration processes and reduced exothermic temperature; in addition, it reduced the flow diameter and the plunger penetration. While assessing the properties of hardened mortar, it may be stated that 5% PS Waste might be used for replacement of a part of cement content.
Pierre Horgue - One of the best experts on this subject based on the ideXlab platform.
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An open-source toolbox for multiphase flow in porous media
Computer Physics Communications, 2014Co-Authors: Pierre Horgue, Cyprien Soulaine, Jacques Franc, Romain Guibert, Gérald DebenestAbstract:Multiphase flow in porous media provides a wide range of applications: from the environmental understanding (aquifer, site-pollution) to industrial process improvements (oil Production, Waste management). Modeling of such flows involve specific volume-averaged equations and therefore specific computational fluid dynamics (CFD) tools. In this work, we develop a toolbox for modeling multiphase flow in porous media with OpenFOAM®, an open-source platform for CFD. The underlying idea of this approach is to provide an easily adaptable tool that can be used in further studies to test new mathematical models or numerical methods. The package provides the most common effective properties models of the literature (relative permeability, capillary pressure) and specific boundary conditions related to porous media flows. To validate this package, a solvers based on the IMplicit Pressure Explicit Saturation (IMPES) methodare developed in the toolbox. The numerical validation is performed by comparison with analytical solutions on academic cases. Then, a satisfactory parallel efficiency of the solver is shown on a more complex configuration.
