Atom Indonesia (E-Journal)
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Temporal Trends and Spatial Relationships of Radioactive Isotopes (I-131, Cs-134, and Cs-137) in Response to Nuclear Events: A Comprehensive Analysis Using Time Series Graphs, Regression, and Multivariate Techniques
Full text linkThis research aims to comprehend the evolution of radioactive isotopes Iodine-131 (I-131), Cesium-134 (Cs-134), and Cesium-137 (Cs-137) over time in diverse locations and analyze their relationships with the independent variables Longitude and Latitude using Linear Regression, Principal Component Analysis (PCA), and Canonical Correlation Analysis (CCA). The data used in this study were processed from the "DE.xlsx" file, including the imputation of missing values with 0 and column transformation into factors. The results of the Linear Regression analysis indicate a significant association between these isotopes and Longitude and Latitude. Additionally, PCA and CCA analyses reveal complex relationships between the isotopes and independent variables. This research provides valuable insights into the historical trends of radioactive isotopes Iodine-131 (I-131), Cesium-134 (Cs-134), and Cesium-137 (Cs-137) in various locations. The novel aspect and uniqueness of this study lie in the utilization of a comprehensive analytical approach, combining Linear Regression, PCA, and CCA to comprehend the relationships between isotopes and specific environmental factors. Moreover, this study significantly contributes to understanding the phenomena of radioactive isotopes and can serve as a foundation for further research in this field. The findings of this research are expected to support efforts in preventing and managing potential environmental and human health impacts of radioactive isotopes in the future
The Effect of Sr2+ and Fe3+ Cations and the Stirring Speed on The Precipitation of Barium Sulfate in a Batch System
Full text linkThe batch system investigation explored the effect of Sr2+ and Fe3+ cations and the stirring speed on the characteristics of precipitated barium sulfate. A series of experiments were conducted to evaluate the rate of barium sulfate precipitation in laboratory equipment from brines containing barium ions (3500 ppm) and varying amounts of Sr2+ and Fe3+ ions (10 and 20 ppm). Kinetic analysis was also performed to explore how stirring speeds (240 and 480 rpm) affect barium sulfate scales' crystallization by increasing the stirring speed and promoting Sr2+ and Fe3+-cation solubility while decreasing the precipitation rate. All solid crystals obtained were mostly pure barite, as the X-ray diffraction (XRD) method confirmed. The SEM micrograph of barite morphology revealed particles with tablet-shaped crystals 2 to 5 nm in size. With the presence of Sr2+ and Fe3+-cation, the shape of barium sulfate was modified into spherical tablets or flower-like clusters of tablets. Meanwhile, the morphological changes could result from increased stirring rates. Moreover, the kinetic results yielded a general reaction rate equation that might be used to estimate barium sulfate deposition in pipelines for various brine, supersaturation, and mixing time durations
Some Metal Oxide-Natural Rubber Composites for Gamma- and Low-Energy X-Ray Radiation Shielding
Full text linkThis work studied protective material consisting of several metal oxide composites (Pb3O4, WO3, SnO2, and Bi2O3)-natural rubber (NR) for X-ray and gamma-ray shielding. The composites were prepared through open milling and vulcanization processes and further characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), rheometry analysis, and density gauge. The attenuation coefficient of the sample was investigated using X-ray generators with voltages ranging from 50 to 140 kV and gamma-ray energies ranging and 356 to 1250 keV, respectively. The experimental results show that the linear attenuation coefficient of NR filled with metal oxides was significantly improved compared to pure NR. For gamma-ray 661 keV, the HVL of NR decreased from 9.0 cm to between 4.4 - 6.2 cm after it was filled with metal oxides. The Bi2O3-NR is the best suitable material for gamma-ray attenuation, followed by Pb3O4-NR, WO3-NR, and SnO2-NR. Meanwhile, for x-rays, the HVL of NR decreased from 2.0 cm to between 0.17 -0.31 cm after it was filled with metal oxides. The proposed metal oxide-NR composites can be appropriate as a flexible protective material for manufacturing wearable radiation shielding products such as gloves, aprons, rubber underwear, and other wearable materials
Comparative Analysis of Turbulence Models for Thermal-Hydraulic Simulations in Aqueous Homogeneous Reactors
Full text linkThis article presents a comparative study of various turbulence models applied in the context of thermal-hydraulic simulations for liquid fuel reactors, specifically Aqueous Homogeneous Reactors (AHR) using Computational Fluid Dynamics. The objective was to assess the suitability of the turbulence models by comparing their results with data obtained from Large Eddy Simulation (LES). For that purpose, was compared the flow behavior predicted using the k-ε, SST, GEKO, DES, SBES, and LES turbulence models. The calculations were carried out in a simplified computational model derived from a pre-existing three-dimensional AHR conceptual design. By utilizing this simplified model, the study aimed to focus on the computational differences between the turbulence models, while minimizing the influence of other factors. The calculation results revealed that the k-ε model exhibited significant discrepancies with the LES, with relative differences for the fuel solution maximum temperature reaching up to 75 %. Among the remaining RANS models, the Shear Stress Transport (SST) model demonstrated the best compromise between accuracy and computational efficiency, with differences below 5 % and requiring only 1/5th of the time, compared to the LES model. The Scale-Resolving Simulation (SRS) models,DES and SBES, provided a more comprehensive description of flow behavior and results closer to LES, albeit with higher computational demands. Between these two models, only the DES model exhibited relative differences below or equal to 1 % compared to the LES model for the studied thermohydraulic parameters
A Two-Dimensional Unsteady FDTD Model for Radon Transport with Multiple Sources Emanation from Soil Layers
Full text linkA two-dimensional numerical model for radon transport based on the finite difference time domain (FDTD) method have been developed. The model is governed by the radon transport equation taking into account the mechanisms of diffusion, advection, and decay. The purpose of this model is to simulate the evolution of radon concentration which can be influenced by various parameters including depth and diffusion coefficient of the soil layer plus the velocity and initial concentration of radon. The obtained results were compared to an analytical solution to demonstrate the ability of this model for predicting the spatio-temporal evolution of radon transport in the porous media of soil layers
Assessment of Health Risk of Exposure to Alpha-Emitters in Cheese Samples Collected from Iraqi Markets
Full text linkIn this research, alpha-emitter concentrations of 222Rn, 226Ra, and 238U in Iranian, Turkish, Egyptian, Saudi Arabian, and Iraqi canned cheeses that are available in Iraqi markets were measured using the CR-39 detector. Also, the health risk parameters associated with the ingestion of alpha-emitter radionuclides, such as the annual average internal effective dose (AAIED) and the risk of an excess cancer fatality per million persons (RECFPMP), were calculated. The results show that the average values of 222Rn, 226Ra, and 228U concentrations for all samples in the present study were 3.7±0.38 Bq/m3, 25.24±2.63 mBq/kg, and 0.025±0.002 ppm, respectively. The average values of AAIED and RECFPMP were 0.175±0.018 µSv/y and 0.674±0.070, respectively. The results show that the highest value of alpha-emitters as well as health risk parameters were found in cheese samples produced in Saudi Arabia, while the lowest results were found in Egyptian samples. They were, nevertheless, less than the permissible value and the risk value. According to the current study, the consumption of those cheese products poses no health risks
Evaluation of Changes in Dose Estimation on Abdomen CT Scan with Automatic Tube Current Modulation Using In-House Phantom
Full text linkThis study evaluates the effect of the Automatic Tube Current Modulation (ATCM) technique on pitch and effective diameter variation in estimating dose values and noise levels for abdominal examination on Philips Ingenuity CT scan machine using in-house Phantoms. The in-house phantoms are oval in shape with three effective diameter sizes, namely 23.2 cm, 28.3 cm, and 33.3 cm to represent abdominal region. The three size Phantoms were scanned using an Ingenuity 128 Philips CT scan with the abdominal protocol exposure parameters of 120 kVp tube voltage, Dose Right Index (DRI) variations of 10,11,12,13, and 14, and pitch variations of 0.6; 0.8; 1.0; 1.2; and 1.49. The changes in mAs, CTDIvol, and noise to the Philips reference value were then verified (i.e. an addition of one DRI value increases mAs by 12 %). For evaluation, a metric to express the change in DRI is defined as ΔDRI. The study demonstrates that noise level is influenced by object size; size information of the object could be useful to predict the change of tube current and pitch due to ATCM with respect to selected DRI. The DRI value is proportional to the tube current, thus selecting the DRI at a certain pitch will directly determine tube current. The ΔDRI in general, according to Philips specifications, is verified to be approximately 10 % to 13 %, except for DRI 10 to 11 which is relatively high on average 15 % to 17 %. Increasing DRI increases the CTDIvol. The CTDI/mAs constantly ranges of 0.06 to 0.07. The value could serve as a characteristic parameter for quality assurance. The ATCM specifications of the Ingenuity 128 CT Scanner is according to Philips regulations
