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Development of BaO-containing radiation-shielding glass using natural dolomite as a raw-material component
(2027-01-01)
Cheewasukhanont, W.
;
Kothan, S.
;
Tungjai, M.
;
Intachai, N.
;
Ruangtaweep, Y.
This study investigates the incorporation of dolomite (CaMg(CO<inf>3</inf>)<inf>2</inf>) as a natural substitute for synthetic CaO in the fabrication of radiation shielding glass (RSG). Dolomite samples from Kanchanaburi, Thailand, were characterized using X-ray fluorescence (XRF) to determine their chemical composition, revealing CaO (76.59-79.84 wt%) and MgO (19.13-21.54 wt%) as the primary components. These dolomites were used to synthesize borosilicate-based host glasses, where density remained stable (∼2.5 g/cm<sup>3</sup>), ensuring structural integrity. Optical transmittance measurements showed an average 80% transparency in the visible range. To enhance radiation attenuation, BaO was incorporated into the glass matrix at varying concentrations (5-35 mol%). Increasing BaO content increased the density of the glass samples, which contributed to improved radiation attenuation performance. The radiation-shielding properties, predicted using WinXCom over a wide photon energy range and experimentally evaluated at 0.662 MeV, improved with increasing BaO content. The HVL, Pb-equivalent thickness, and EABF results further supported the enhanced attenuation performance of the developed glasses, indicating that higher BaO content reduced the contribution of scattered photons to absorbed energy buildup in the intermediate-energy region. In addition, preliminary glass-forming tests of the B4 composition demonstrated the feasibility of preparing a larger glass sheet under similar melting and annealing conditions, although further optimization is still required. These findings suggest that natural dolomite can serve as a useful raw-material component for developing BaO-containing radiation-shielding glass with balanced optical transparency, density, and attenuation performance.
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Relationship between groundwater properties and soil salinity at the Lower Nam Kam River Basin in Thailand
(2013-07-01)
Seeboonruang, Uma
The Lower Nam Kam River Basin lies in the vicinity of the Mekong River and is located in the eastern section of the Nakhon Panom Province in northeastern Thailand. Drought, particularly in the winter and summer seasons, is the main environmental challenge in this area. In addition, soil becomes saline and groundwater is brackish in some locations. This problem worsens the drought crisis in the area. Groundwater is known to closely relate to the soil salinity distribution. To successfully manage highly saline areas, saline groundwater and soil properties must be evaluated together. Therefore, the main objective was to study the shallow groundwater physical and chemical properties in conjunction with surface soil salinity. Soil samples were collected and measured for physical and chemical properties. Shallow groundwater was measured for depth from ground surface and sampled from the sites in the study area. The water samples were measured for pH, total dissolved solids, electrical conductivity, and salinity. Results were interpolated and displayed via a geographic information system and further analyzed by simple linear regressions between surface soil salinity and the other factors. The results show that the topsoil contaminated with salinity is typically situated in relatively low areas with shallow groundwater levels and low head gradient of groundwater. This is due to the characteristics of the soil profile and groundwater depth. © 2012 Springer-Verlag Berlin Heidelberg.
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Upscaling heterogeneity in aquifer reactivity via exposure-time concept: Forward model
(2006-03-20)
Seeboonruang, Uma
;
Ginn, Timothy R.
Reactive properties of aquifer solid phase materials play an important role in solute fate and transport in the natural subsurface on time scales ranging from years in contaminant remediation to millennia in dynamics of aqueous geochemistry. Quantitative tools for dealing with the impact of natural heterogeneity in solid phase reactivity on solute fate and transport are limited. Here we describe the use of a structural variable to keep track of solute flux exposure to reactive surfaces. With this approach, we develop a non-reactive tracer model that is useful for determining the signature of multi-scale reactive solid heterogeneity in terms of solute flux distributions at the field scale, given realizations of three-dimensional reactive site density fields. First, a governing Eulerian equation for the non-reactive tracer model is determined by an upscaling technique in which it is found that the exposure time of solution to reactive surface areas evolves via both a macroscopic velocity and a macroscopic dispersion in the artificial dimension of exposure time. Second, we focus on the Lagrangian approach in the context of a streamtube ensemble and demonstrate the use of the distribution of solute flux over the exposure time dimension in modeling two-dimensional transport of a solute undergoing simplified linear reversible reactions, in hypothetical conditions following prior laboratory experiments. The distribution of solute flux over exposure time in a given case is a signature of the impact of heterogeneous aquifer reactivity coupled with a particular physical heterogeneity, boundary conditions, and hydraulic gradient. Rigorous application of this approach in a simulation sense is limited here to linear kinetically controlled reactions. © 2006 Elsevier B.V. All rights reserved.

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