Papers by Keyword: Neutron Activation Analysis

Abstract: Heavyweight concrete is mostly used for its shielding properties in the nuclear power plants. These properties can already be influenced by the selection of the input materials. In the present study, concrete samples comprised of four-component binders based on CEM I 42.5 R, blast furnace slag, metakaolin and limestone and a mixture of barite and magnetite aggregate, were investigated. Based on Energy Dispersive X-ray Fluorescence, Neutron Activation, and Prompt-Gamma Activation analyses, three concrete designs were prepared and tested. Mechanical, physical (namely cubic compressive strength, bulk density, longitudinal deformation, and dynamic modulus of elasticity) and thermal properties (thermal conductivity coefficient, specific heat capacity, and thermal diffusivity), which should be influenced by the long-term exposure to irradiation were investigated. Presented results confirmed that the prepared samples are heavyweight concrete with bulk density higher than 3400 kg.m-3 with a low level of longitudinal deformation (between 0.265 ‰ and 0.352 ‰). All the prepared samples belong to the C 35/45 concrete strength class.

Abstract: The aim of this work was to develop technical analysis of wavelength dispersion X-ray fluorescence (WDXRF) and compare with technical neutron activation analysis (NAA). First, the standard of tin oxide (SnO) was ground into powder and mixed with boric acid (H₃BO₃) as binder at different weight. All of samples were investigated by WDXRF in normalize mode.The results indicated that the range can use to calibration at sample weight 0.2, 0.3 and 0.4 g. Next, the three SnO samples from different area (A, B and C) were ground, mixed with binder at ratio 0.2, 0.3 and 0.4 g and investigated by WDXRF in normalize mode. The results show tin (Sn) content of sample area A, B and C were 75.71, 74.61 and 71.01%, respectively. The result from NAA technique show Sn content of sample A, B and C were 79.36, 77.48 and 73.35%. The percentage error of WDXRF and NAA technique of the samples from the different area had 4.63, 3.70 and 3.19%. From the experiment as examined that the WDXRF technique could be improve process for determine chemical composition which one of choice for easy to used and low cost.

Abstract: Neutron activation analysis (NAA) is a method of nuclear technique to detect with great sensitivity the presence and concentrations of elements in materials, without, in most cases, destroying the sample analyzed. Therefore, this study aimed to study the technique of Neutron Activation Analysis (NAA). Accordingly, instrument (INAA) has been in this analyzed for determination of heavy toxic metal (Cd, Co, Fe, Pb, Cr, Zn) and others in vegetables samples. The results of heavy metal concentration analyses showed that Co, Fe, Cr could be analyzed by NAA.

Abstract: When assessing the environmental situation in territories, where industrial plants or combined heat and power stations (CHPs) are situated, a special interest is paid to determining the size of the area of heavy metal (HM) deposition, due to their high toxicity and ability to accumulate in human body. Over the last decade, the estimation of air heavy metal content widely implements the method of moss biomonitoring. This work analyses a three-year amount of moss growth. Sampling was carried out in the northeastern direction from CHP-5 (Novosibirsk, Russia) in accordance with the wind rose at distance varying from 1 to 5 km. The study includes preparation and analysis of 38 samples of moss by neutron activation method. The work is based on the measurement of the concentration of various heavy metals and frequency of wind occurrence in seven main directions.

Abstract: Trace element determination is crucial for identifying the provenance and authenticity of intact ancient objects such as cultural and art artefacts, archaeological findings and forensic materials, geological objects, etc. A non-destructive technique suitable for analysis of trace elements in bulk-samples is highly needed. The IAEA initiated a series of coordinated research projects (CRP) to support Member States on their R&D programs. Large Sample Neutron Activation Analysis (LSNAA) is a very attractive non-destructive technique that can be applied without a need for sub-sampling and homogenization. LSNAA can be operated in ‘on-line’ mode which is based on the use of isotopic neutron sources, neutron generators and prompt gamma analysis. An on-going CRP focuses primarily on the application of LSNAA in the area of archaeological and geological programmes. However, further utilization of LSNAA in other subjects of industry and research is promising. Large scale campaigns of archaeological excavations are undertaken in the Mediterranean region. The IAEA is supporting Technical Cooperation projects in the Middle East in view of studying authenticity and origin of objects of art and archaeology, as well as to characterize new elaborated materials or environmental samples, making use of Ion Beam Accelerators (IBA) as nuclear analytical tool and other nuclear analytical techniques. The application of nuclear analytical tools in archaeology is of special concern as many common ancient civilizations are shared by the Mediterranean state. The main IBA techniques to be used are: PIXE, PIGE and RBS, as well as XRF. To take advantage of these nuclear techniques, many researchers from the participating countries have initiated several studies and exchange of experience, knowledge, results and expertise is on-going.

Abstract: This paper investigates the impact of iron (Fe) and molybdenum (Mo) when they are introduced in the feedstock for mono- and multicrystalline Float-Zone (FZ) silicon (Si) growth. Neutron Activation Analysis shows that the segregation coefficient is in agreement with literature values. Lifetime maps on monocrystalline wafers show a uniform lifetime which decreases with the increase of contamination levels. Multicrystalline wafers show low lifetime areas, corresponding to grain boundaries and highly dislocated areas, which are independent from the contamination levels. Intra grain areas have a higher lifetime which changes with the contamination levels. The solar cells show a reduced diffusion length in multicrystalline uncontaminated cells compare to the monocrystalline uncontaminated. In multicrystalline cells the lowest level of Fe introduced (1012 atm/cm3) has hardly any influence, whereas in the Mo-contaminated cells the impact is visible from the lowest level (1011 atm/cm3). In monocrystalline cells the diffusion length is reduced already at the lowest contamination level of Fe.

Abstract: Impurity atoms in a high-purity semi-insulating 4H-SiC substrate fabricated by sublimation and an n-type 3C-SiC substrate fabricated by Chemical Vapor Deposition (CVD) were evaluated by neutron activation analysis. Cr, Fe, Zn, As, Br, Mo, Sb, Eu, Yb, Hf, Ta, W and Au atoms were detected in the 4H-SiC fabricated by sublimation. In the 3C-SiC fabricated by CVD, Cr, Zn, As, Br, Mo, Sb, La Sm and Hf atoms were found. The concentration of these atoms tends to decrease with increasing atomic number.