Atom Indonesia (E-Journal)
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Calculated Electronic Energy Loss of Heavy Ions at Low Energies in LR-115, Kapton, SiO2, and Al2O3 Amorphous Materials
Get PDFThe electronic stopping powers of LR-115 and Kapton polymeric foilshave been estimated, using Monte Carlo simulations, for 9Be, 11B, 12C, 14N, 16O, and 35Cl ions covering the energy range ~0.1-1.0 MeV/n. Comparison of stopping power based on Lindhard, Scharff, and Schiott (LSS) theory with the corresponding values obtained by SRIM and MSTAR codes in LR-115 and Kapton polymeric foils illustrate a significantly large deviations. However, a semiempirical equation has been proposed here and tested for better stopping power calculations at low-energy regime in the domain of LSS theory for Z = 4-8 ions across materials. Furthermore, the electronic energy losses for 9Be and 16O ions in SiO2 and Al2O3, respectively, have been calculated in the energy range of ~0.1-1.0 MeV/n. The calculated stopping powers exhibit up to 10 % deviation from the experimental values and MSTAR data
Impact of Tube Voltage on Radiation Dose (CTDI) and Image Quality at Chest CT Examination
Get PDFDuring Computed Tomography (CT) scan examinations, it is important to ensure a good diagnosis by providing the maximum information to detect pathologies and this can be done with a reduced dose. In this respect, several methods of dose reduction have been studied and evaluated. This work investigates the effect of tube voltage while varying the tube current on image quality and radiation dose at Chest CT examination. This study was conducted on HITACHI CT 16 slice Scanner using two phantoms for evaluating the dose and image quality; a PMMA phantom and a CATPHAN 500. Two tube voltages of 120 KVp and 100 KVp have been used for some variation of the tube currents (mAs) and recording the values of the measured quantities (CTDIv, spatial resolution, contrast to noise ratio CNR and noise). The scanning with 100 KVp at Chest CT examination led to a reduction in CTDIv until 45 %, an increase of noise from 17 % to 45 %, and the Spatial Resolution fell slightly (6 and 7 pl/cm) compared to the 120 KVp. The CNR shows a slight regression from 11 to 22 % for the 120 KVp and 100 KVp. This study has shown that despite the increase in the image noise at low tube voltage 100 KVp, it is possible to reduce the radiation dose by up to 45 % without degradation of image quality at Chest CT examination. Further works will evaluate the effect of acquisition parameters in other CT examinations
Gamma Radiosynthesis of Colloidal Silver Nanoparticles Stabilized in ι-Carrageenan Under Atmospheric Gases: A Surface Plasmon Resonance Based Study
Get PDFι-Carrageenan is a biodegradable and biocompatible biomaterial which potentially stabilizes colloidal silver nanoparticles (AgNPs). The present study explored gamma radiosynthesis of AgNPs at varied concentration of ι-carrageenan solutions. The reaction system contained 1.0 mM silver precursor from silver nitrate salt. Gamma irradiation was conducted at doses up to 20 kGy under simple condition, i.e., atmospheric gases and without addition of hydroxyl radical scavenger. The behavior of AgNPs in suspension was characterized based on their surface plasmon resonance (SPR) absorption spectra which were measured using UV-vis spectrophotometer. The results show that colloidal AgNPs were successfully radiosynthesized due to dual stabilizing/reducing activity of ι-carrageenan. The degradation product of ι-carrageenan shows antioxidant activities, which increase the reducing condition of the reaction system. TEM micrograph reveals that the nanoparticles are spheroid in shape and monodisperse with an average particle size of below 10 nm. The SPR spectra indicate that the highest AgNPs concentration is found for irradiation at a dose of 10 kGy and ι-carrageenan concentration of 1.0 % (w/v). However, instability of AgNPs occurred a day after radiosynthesis due to oxidative dissolution and agglomeration. Further works on pH adjustment and optimization on irradiation dose and ι-carrageenan concentration are critical to improve the stability of colloidal AgNPs
Evaluating the Diffusion Approximation Capability on the Integral Pressurized Water Reactor (IPWR) Core Calculation
Get PDFDiffusion approximation is an important approximation used to model a nuclear reactor core with a quite good accuracy and less computational cost. This approximation has been used widely around the globe for various kinds of nuclear reactors. This diffusion approximation is applied in a two-step method, a method combining a high fidelity transport code and low fidelity diffusion code. Meanwhile, innovations in the nuclear core model continue to make the nuclear reactor core safer, more robust, and smaller. The trend of creating smaller and more modular reactor core is emerging in the last ten years. These innovations will affect the core modeling system. Consequently, for smaller reactors, it is important to evaluate the capability of diffusion approximation if one wants to use a computationally cheaper method to model the reactor core. In this paper, neutron diffusion calculation for 160 MWth integral pressurized water reactor (IPWR) core was conducted using the PARCS nodal diffusion code employing the few-group spatially homogenized cross-sections generated by the Serpent Monte Carlo code. Due to its capability to model any reactor geometry in the high-resolution calculation, the results from Serpent were also used as a reference. Two important parameters are compared between PARCS and Serpent: effective neutron multiplication factor and core power distribution. For the full IPWR core model, a discrepancy of 564 pcm between PARCS and Serpent keff was observed, while the radial power distribution had a maximum error of 4.71 %. It can be said, to some extent, that the diffusion approximation can be applied to IPWR core analysis. However, further improvement is indeed required if one wants more accurate results with low computational costs
Model Comparison of Passive Compact-Molten Salt Reactor Neutronic Design Using MCNP6 and Serpent-2
Get PDFPassive Compact Molten Salt Reactor (PCMSR) is a thermal breeder molten salt reactor (MSR) developed in Universitas Gadjah Mada, Indonesia, run in thorium fuel cycle. Its design was initially developed using deterministic code SRAC2006 but has never been compared with other codes. This paper attempts to compare PCMSR neutronic design using Monte Carlo codes MCNP6 and Serpent-2 with ENDF B/VII.0 continuous neutron cross-section library. The reactor was run in a pure thorium fuel cycle with lithium fluoride as its carrier salt. The analyzed parameters were effective multiplication factor (keff), temperature coefficient of reactivity (TCR), void coefficient of reactivity (VCR), and conversion ratio (CR). The result shows that there are several important discrepancies between the original calculation and this research. The Monte Carlo calculations implied that PCMSR core was able to be critical using lower fissile concentration than previously designed, but failed to reach CR above unity. While the TCR value was found to be negative, the VCR value was positive up until the 10 % void fraction. The PCMSR core suffered from ineffective neutron moderation and high neutron leakage. These findings imply that the previous PCMSR neutronic design is inaccurate. For PCMSR to be able to operate as a thermal breeder MSR, geometrical modifications must be performed to improve neutron moderation and reduce neutron leakage
Theoretical Inspecting of 211At Radionuclide via Coupled-Channel Model for Fusion Reaction of Stable Nuclei
Get PDFThis work has been carried out to obtain and inspect of 211At radionuclide through fusion reaction. Cross-sections for fusion reaction have been calculated with different interaction combinations and excitations for 19F + 192Os and 18O + 193Ir reactions. All calculations have been performed on NRV Knowledge Base, CCFULL code, and Wong’s Formula. Firstly, we assigned reaction parameter values taking into account the compatibility with the experimental data 19F + 192Os reaction. Afterward, to enrich studies on 211At radionuclide, we proposed 18O + 193Ir reaction which did not have experimental data in the literature with the method and parameter values we determined. We examined the effects of phonon excitations in projectile and target nuclei on fusion cross sections and barrier distributions. With our research, we showed that the coupled channel model and the calculation codes used to explain the fusion cross-section data and barrier distributions well. This research sheds light on the importance of analyzing important medical radionuclides such as 211At by heavy-ion fusion reactions and encourages new researches
Radon Concentrations in Canned Liquid Juice
Get PDFThis study was performed at University of Kufa, Iraq, using canned liquid juice samples found in Iraqi markets due to the absence of environmental contamination from radionuclides emitting 222Rn concentrations using RAD-7 detectors. The annual effective dose (AED) of 222Rn was estimated for children and adults from the ingestion of canned liquid juice samples. The estimated concentrations of 222Rn in unit (mBq/L) ranged from 35.4 to 249.1, with an average of 77.880.24 ± 15.42. It also shows that the AED values for children and adults in (nSv/y) ranged from 19.11 to 134.48 with an average of 43.31 ± 8.32 and from 22.67 to 159.55 with an average of 51.39 ± 9.88, respectively. All estimated results of 222Rn concentrations for juice samples were lower than the natural limits provided by the WHO and the European Union Commission to the public (0.5 and 1 Bq/L, respectively). Therefore, there are no health hazards from drinking juice sold in Iraq markets
Study of Dried and Calcinated Ceria Stabilized Zirconia Microspheres Morphology by Small-Angle X-Ray Scattering and Optical Microscopy
Get PDFThe knowledge of how to avoid crack at high temperature is crucial in fuel fabrication for Experimental Power Reactor or Reaktor Daya Eksperimental (RDE). This knowledge should be established and well-mastered by BATAN. RDE uses uranium dioxide as its nuclear fuel. However, uranium utilization for research purposes is heavily restricted. Therefore, the fabrication of ceria-stabilized zirconia (CSZ) microspheres as nuclear fuel surrogate was studied. In this work, the CSZ was prepared by external gelation with two different washing solutions, i.e. isopropyl alcohol (IPA) and propylene glycol methyl ether (PGME). The morphology in nano- and micro-scale of each CSZ microspheres from both variations was evaluated by small-angle x-ray scattering (SAXS) and optical microscopy. The morphology of the CSZ microsphere after drying at 80 °C and calcination at 200 °C were observed to understand the structural change in those steps and to see the potential crack based on its morphology. There are two parameters that can prevent microspheres from cracking at high temperatures for the next process, i.e., porosity and gel texture. It was observed that IPA solution has a benefit as a washing solution as it can trigger more porosities in the microspheres, but less in gel texture
