Non-destructive multielement analysis of airborne particles by instrumental neutron activation analysis

Instrumental neutron activation analysis (INAA) was used for the determination of the elemental composition of aerosol samples. Two samples of air of approximately 20 m3 each one were collected of the atmosphere around the Es-Salam research reactor site in Algeria. The irradiation of the samples and reference materials was carried out during 30 s for the elements of short half-life and 06 h for the elements of medium and long half-life with a thermal neutrons flux of 1.12 1013 and 6.88 1013 n/cm²s respectively. Ge(Hp) g-spectrometry made it possible to determine  fifteen  elements (Al, Cl, Mn, Ca, Cd, Br, La, Fe, Nd, Ce, Hg, Cr, Hf, Sb and Zn). The obtained results for the used reference materials almost perfectly match its certified values (Zscore<2)

Stability of flowing PbLi alloy between coaxial cylinders under magnetic field

In this research, numerical simulations were performed to investigate the stability of a flowing PbLi alloy (Pr = 0.032) within two coaxial vertical cylinders, while subjected to an axial magnetic field. The primary objective of this study was to analyze how the presence of the axial magnetic field affected both vortex breakdown and swirling flow phenomena. To achieve this, the governing equations, which included the Navier-Stokes equations and potential equations, were solved using the finite-volume method. The numerical simulations presented results for three aspect ratios (A= 1.5, 2.0, and 2.5) and three annuli (R = 0.9, 0.8, and 0.7). In the hydrodynamic scenario, vortex breakdown was observed close to the inner cylinder as a result of the intensified pumping effect caused by the Ekman boundary layer. The findings demonstrated that the onset of oscillatory instability was initiated by increasing the Reynolds number to a critical value. However, when a magnetic field is intensified,  the vortex breakdown vanishes, and its limits will shrink. Stability diagrams were created to depict the boundaries within which a vortex breakdown bubble emerges, allowing for a visual picture of its occurrence

The Adsorptive properties of 4-Hexyl-tertrahydro-thiopyran-1,1-diode on Al(110) and Fe(111) surface using DFT method

Aluminum and iron are highly significant industrial commodities that are used to make anything from tools and concrete construction to roofing sheets and other roofing-related products. Even though they generate a protective oxygen barrier that prevents corrosion, they are nevertheless susceptible to corrosion in extreme conditions. In order to achieve the stable shape of the molecule HTTD, a theoretical investigation on the corrosion inhibition of metals like Aluminum and iron was conducted utilizing local density function B3LYP under limited spin polarization DNP foundation. The values of local/global reactivity parameters, including the (ω+) electroaccepting power and (ω-) electrodonating power between the inhibitor molecule and the metal surfaces, were demonstrated. These parameters included EHOMO, ELUMO, energy gap (∆Eg), electronegativity (χ), global hardness (η), global electrophilicity index (ω), and fraction of electron transfer (∆N). Physisorption mode was defined as the mode of interaction of HTTD on Aluminium and Chemical Adsorption on Iron surface based on the simulation modeling output. The outcome of Fukui functions revealed that the focus point for the selectivity of electron donation and acceptance between the metal and the moiety is a hetero-atom present in the molecule such as oxygen, sulfur and the methylene (-CH2-) functional group

Enhanced approach for CDF quantification in Seismic Probabilistic Safety Assessment of a Research Reactor

In Probabilistic Safety Analysis (PSA) applications, it is common practice to employ approximations with the expectation or assumption of a small overestimation in the quantification of the Core Damage Frequency (CDF). The overestimation of the CDF depends on the Minimal Cut Sets (MCS) structures and event probabilities but the amount of conservatism is generally unknown. Hence, when dealing with large and non-coherent fault trees, conventional approaches to model dependencies in event trees analysis using coherent approximations are shown to be inaccurate. The limitation of the techniques in terms of accuracy of the solutions becomes apparent. For instance, the quantification methods using Rare Event (REA) and Min Cut Upper Bound (MCUB) approximations valid in internal event PSA may result in excessively conservative results in Seismic PSA. Therefore, in order to calculate the accurate top event probability from a fault tree rather than improving the direct probability calculation from cut sets, the Binary Decision Diagram (BDD) is introduced for more exact quantification. BDD development highlights the effort to reduce the conservatism caused by RAE and MCUB computations. The analysis carried out in this work, within the Seismic Probabilistic Safety Assessment (SPSA) of a nuclear Research Reactor (RR) case study using BDD framework shows that the approach is feasible and effective in evaluating the seismic risk of core damage and provide reasonable assurance that related decisions on real-time risk status can be taken robustly and with confidence

Studies on the separation of Uranium from Algerian yellow cake using different processes: impurities determination

Analysis of impurities in uranium materials is crucial for quality control or the purity required by standards in the nuclear industry. This study involves the analysis of impurities in a sample of uranium ore concentrate produced from Tahaggart ore. The instrumental techniques used for the analysis are highly sensitive and susceptible to much interference following the uranium spectrum. Different processes for separating uranium from impurities for comparison were used to quantify them. The uranium sample is an Algerian yellow cake that was digested in nitric acid, separated by solvent extraction using the TBP/CHCl3 system, by extraction chromatography method using tributyl phosphate (TBP) impregnated on the Amberlite XAD-7 resin and by precipitation of uranium with hydrogen peroxide. The raffinate from each process is then analyzed by flame atomic absorption spectroscopy and flame photometry. The concentration of uranium is determined by the Potassium Bichromate method in concentrated solutions and by the Arsenazo III method in raffinates and eluates. Uranium extraction yields are 99.65% using TBP-CHCl3 and exceed 99% using TBP-impregnated XAD-7 resin. The results of the analysis of impurities in Algerian yellow cake after the separation of uranium using different processes show that the contents meet the ASTM C967-13 standard for the elements analyzed except for the iron element. A comparison of the results of the impurities analysis values in Algerian yellow cake by the three separation processes (liquid-liquid extraction (ASTM C761-11), extraction chromatography column, and precipitation) shows the absence of cadmium, titanium, lead, and chromium and the values of the manganese, zinc, and lithium are quite close. The analysis results for the solvent extraction and chromatographic column extraction processes showed that the values of magnesium, copper, and nickel are very close and identical for cobalt. The values of aluminium and iron are close

Development of a two-row manually operated rice transplanter for smallholder farmers in Nigeria

A two-row rice transplanting machine was developed for smallholder farmers in Nigeria using standard-approved methods and locally available materials. The transplanter was designed in such a way that one operator can operate the machine. The machine consists of ground wheels, sprockets, chain, frame, float, transplanting mechanism, seedling tray, shaft and handle. The developed rice transplanter was evaluated based on a 2 x 2 x 3 factorial experimental design arranged in a strip plot design to ascertain its operational performance. The performance parameters of the rice transplanter revealed a field capacity and efficiency of 0.0146 ha/h and 55.66%, respectively. A variation in the distance between the hills was observed. The mean values were found to be 322.9 mm. The number of seedlings dispensed per hill varied in different plots. In most cases, 2-3 numbers of seedlings are dispensed per hill. The depth of the hill varies between 23 mm to 38 mm respectively. The mean depth was found to be 30.33 mm. The mean percentage of the missing and floating hills was 40% and 45%, respectively. The missing and floating hills were high in the transplanted plot. Results obtained from the analysis of variance show that the effects of treatment tillage operation and water depth have a significant effect on the machine. Based on the result obtained it can be concluded that more performance evaluation with machine and soil parameters needs to be conducted on the machine. This technology is recommended for use in rural areas to increase productivity by rice farmers

Study of the elaboration of U3O8 by the Modified Direct Denitration process (MDD)

In the nuclear industry, uranium trioxide (UO3) is considered an intermediate in the preparation of uranium metal or uranium dioxide (UO2), which are the two most widely used nuclear fuels. Several processes have been described for transforming solutions of uranyl nitrate UO2(NO3)2 into uranium trioxide. Among these processes, Modified Direct Denitration (MDD) has been implemented to prepare Uranium trioxide with high reactivity. This process consists of adding ammonium nitrate to a pure uranyl nitrate solution to form the double salt (NH4)2UO2(NO3)4.2H2O which decomposes by calcination to produce a UO3 powder. The objective of this work is to study, first, the thermal decomposition of double salt (NH4)2UO2(NO3)4.2H2O in nitrogen atmosphere by thermogravimetry in order to determine the formation temperatures of the different phases and second, the determination of the optimal parameters (time and temperature) to prepare stable triuranium octoxide (U3O8) using muffle furnace. As results, the MDD product obtained is an orange colored and free flowing UO3 powder, having a surface area in the target range [5-12 m2/g]. In addition, by calcination of UO3 powder at 650°C for one hour, U3O8 oxide is obtained. The identification of the latter by the O/U ratio gave a value of 2.65, which is in the range [2.6-2.66]. This suggests that the oxide produced under these conditions is β-U3O8

Numerical simulation of time-fractional Navier-Stokes equation in cylindrical coordinates for an unsteady one-dimensional motion of a viscous fluid flow in a given tube

This paper proposed and applied a three-step computational algorithm to solve the time-fractional Navier-Stokes equation (FNS) in a given cylindrical coordinates for one-way unstable flow motion. The Caputo definition of fraction order was obtained using the Riemann Liouville fractional integral operator, which was coded with the MAPLE18 software command and applied to simulate the different fractional values ​​presented in 2D and 3D surface graphs for understanding better the operation of fractional Navier-Stokes equations over time in cylindrical coordinates. We considered different test cases to show the proposed algorithm's efficiency, robustness, and feasibility, which ultimately reduces the computational time and ease of implementation for the simulation of the fractional order of the fractional Navier-Stokes equation considered

Sol-gel synthesis of ZnO nanoparticles for optmized photocatalytic degradation of Eriochrome Black T under UV irradiation

In this work, zinc oxide (ZnO) nanoparticles was synthesized by sol-gel method and characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), energy dispersive spectroscopy (EDS) and ultraviolet-visible (UV-Vis) spectrophotometry. The XRD analysis of the as synthesized catalyst revealed a hexagonal wurtzite structure. The average particle size and band gap values were 24.67nm and 3.28eV respectively. The peak observed at 452cm-1 corresponds to Zn-O stretching vibrational band. The effect of operating paramers such as initial concentration of eriochrome black-T (EBT), concentration of catalyst and pH of the solution was optimized using box-benhken design (BBD) and response surface methodology (RSM). The optimum photodegradation efficiency of 96.59% was obtained at 15.00mg of EBT concentration, 0.40g  catalyst concentration and initial pH of 9.00. The degradation model was statistically remarkable with p < 0.0001% in which the EBT initial concentration and catalyst concentration were the most significant variables influencing the degradation of EBT over ZnO photocatalyst under UV irradiation

An overview of the relative neutron activation analysis performed in the NAA Laboratory of the CRND using NUR reactor

Neutron activation analysis is a highly sensitive method for multi-elemental analysis, primarily focusing on the induced radioactivity in atomic nuclei rather than the inherent chemical and physical properties of samples. This approach requires exposing the sample to neutron irradiation, typically conducted within a nuclear reactor. One of the most successful applications of Instrumental Neutron Activation Analysis (INAA) in the vicinity of the NUR reactor pertains to its use in environmental studies. It facilitates the monitoring of the distribution of trace elements (TEs) and the attribution of emission sources by analyzing samples from diverse environmental sources, including soil, air, and bioaccumulative plants collected from various locations near Algiers, Algeria. Since 2010, our laboratory has actively engaged in proficiency tests with WEPAL/IAEA, which has been instrumental in advancing and refining the methods of Neutron Activation Analysis (NAA) employed in this domain. The outcomes derived from these environmental investigations substantiate the presence of more than 30 trace elements. Comparing the enrichment factors (FEs) reveals the contribution of anthropogenic pollution, such as vehicles emitting Sb, Se, and Zn, brickyards releasing As, Co, Cr, Fe, Na, Se, Sc, Ta, and Tb, as well as soil resuspension leading to the release of Br and Zn. Additionally, our laboratory has conducted further studies in the realm of biology using the relative approach of NAA. The primary objective has been to harness the potential of NAA for early diagnosis in cases of cancer and chronic diseases. Consequently, we've examined the trace element composition in the whole blood of both healthy individuals and those afflicted by illnesses. We achieved this by subjecting lyophilized blood samples from adult subjects to simultaneous irradiation alongside an A13-IAEA blood standard. The elemental concentrations were subsequently calculated by measuring gamma rays using a gamma spectrometer. We simultaneously determines the concentrations of ten elements: Rb, Fe, Zn, Na, K, Br, Se, Sr, As and Sc