Journal of Nuclear Research and Applications
Volume:4 Issue: 1, Winter 2024

Fluorine cold plasmas are recognized as effective dry processing techniques for removing surface contaminants with high bond energy. Among the radionuclides, 58Co and 60Co pose significant challenges. The removal of Co isotopes from contaminated metal surfaces is a key focus in developing metal surface cleaning processes. This study aimed to investigate the plasma reaction resulting from the discharge of a dielectric barrier in fluorine gas. This plasma was interacting with a Cobalt oxide film on the surface of stainless steel 304 through experimental observation and simulation study. It was observed that the Cobalt oxide transformed into a powdered form after exposure to plasma irradiation, enabling easy separation from the base metal surface. The efficiency of clearance from the metal surface depends on the generation of fluorine (F) radicals within the plasma. To identify the crucial parameters influencing plasma formation and optimization, the plasma created using CF4 etching gas was simulated using Comsol Multiphysics software. The simulation study reports there are optimal values for voltage, frequency, and the distance between the two electrodes, which enhance cleaning speed. In addition, increasing the temperature will speed up the etching process

Incorporating multifunctional nanostructured materials that absorb radiation into polymers enhances their radiation-shielding properties. The role of boron nitride (BN) as an effective filler to enhance the mechanical and shielding properties and resist the deteriorating effects of irradiation has yet to be studied in detail. Our study examined the effects of gamma radiation doses ranging from 0 to 100 kGy on the mechanical properties of high-density polyethylene (HD) reinforced with two types of BN with different dimensions: hexagonal boron nitride (hBN) and boron nitride nanosheets (BNNSs). Scanning electron microscopy micrographs showed some aggregated plates with good distribution uniformly distributed in all regions in the matrix, which suggests proper adhesion between polyethylene and BN. The study showed that HD, 1 wt.% composite, and 1 wt.% nanocomposite samples experienced a 58%, 47%, and 33% reduction in elongation at break at 100 kGy compared to nonirradiated samples. The loss of tensile strength at 100 kGy for HD, 1 wt.% composite, and 1 wt.% nanocomposite was 57%, 44%, and 44%, respectively, compared to the nonirradiated samples. It is concluded that the addition of BNNSs in lower dimensions than hBN into polyethylene reduces the destructive effects of radiation and is a way to improve the stability of polymer shields against ionizing radiation.

In this paper, some thermophysical properties of light and heavy water will be predicted and modeled using the virial equation of state (VEOS), and the effect of isotopic substitution will be studied. In this respect, by fitting the experimental and theoretical data of the second virial coefficient of light and heavy water in the temperature range of 300 to 1800 K, a new equation will be presented, using which the thermodynamic properties of the aforementioned fluids will be predicted and . The results are compared with the experimental data to evaluate the model and the new equation of the second virial coefficient. The results show that this approach has a very good ability to predict the thermophysical properties of light and heavy water. It will also demonstrate that deuterium isotopic substitution reduces the attractive interaction between molecules, especially above the critical temperature, and this causes the difference in the thermodynamic properties of the two fluids. The calculations performed in the above temperatures and pressure range using viral coefficients to determine thermophysical properties of light and heavy water and also the investigation of the effect of isotopic substitution are novelties of this article.

An organic-inorganic nanocomposite 198Au/PD4G was synthesize using polyamidoamine G4 dendrimer and applied as an anticancer agent against 4T1 carcinoma tumor as well as for biodistribution and human absorbed dose investigation. Radionuclide 198Au was produced by irradiation of natural gold (197Au) in a medium flux reactor with 3×1011n/cm2.s flux of thermal neutron. Gamma spectroscopy exhibited only one characteristic peak of 198Au at 411 KeV as well as a radiochemical purity of more than 82% (using ITLC) was obtained for final formulation of 198Au/PG4D (37MBq). A single intratumoral injection of 88μCi of 198Au/PG4D resulted statistically significant 65% reduction in 4T1 tumor volume after 20 days. Biodistribution investigations showed that the tumor had a maximum 198Au/PG4D uptake of 81.27% and 79.37% at 4 and 24 h post injection. The human’s absorbed dose, furthermore, was extrapolated via the biokinetics data of mice so that the doses absorbed in the critical organs such as the bone, lung, spleen, kidney, and liver are 0.0669, 1.1, 0.221, 0.0983 and 0.282 mGy/MBq, respectively.

A portable body counter detects internal contamination in an emergency. Monte Carlo code estimates minimum detection activity (MDA) for a portable whole-body counter. In the case of outdoor open fields, natural background radiations were simulated. This counter has a chair geometry equipped with a NaI (Tl) detector (5cm x 5cm) inside a lead shield collimator consisting of a set of lines and a continuous component with monenergistic γ sources ranging from 300 to 2000 keV at intervals of 100 keV. This data matrix is folded with the measured spectrum outside the setup to estimate the observed spectrum in the detector. We evaluated the variation of the detector flux transmitted through the lead collimator and chair shield. This was done at different lead densities and different photon energies. Computational data were used to estimate the monitoring system MDA. This method is cheaper to design and test a counter system for low-level counting of γ emitting radionuclides than experimental methods

One of the key influencing parameters in the safe management of nuclear waste repositories is the distribution coefficient ( ) of radionuclides on bedrock. In this study,  of uranium and thorium ions in intact bedrock were determined using batch experiments on crushed bedrock at seven different particle size fractions as well as three different initial concentrations of ions. Sorption experiments have been performed on crushed bedrock prepared from intact drill core samples and an aqueous solution containing desired ions from the local water (LW) near Anarak Nuclear Waste Repository. The results showed that both factors of the initial ions concentration as well as the size of the crushed bedrock particles significantly affect the value of the distribution coefficient so that (  value increases with decreasing particle size and increasing ion concentration. Also, ( calculated at three studied concentrations showed that the difference in the ( values in smaller particles is large but decrease with increasing particle size and ( ) curves for two concentrations of (100 and 10) ppm overlap at the end of the chart. Therefore, it can be concluded that for accurate calculation, it is better to use large particles and low concentrations of ions to determine ( ) in intact bedrock. In this report, different mechanisms including chemical interactions, physical adsorption, and ion exchange were presented for ion adsorption by bedrock. The proposed mechanisms were related to the type of metal speciation of ions in the solution. Based on the obtained data, the preferred mechanism to describe the adsorption of uranium and thorium ions is composed of chemical interactions and physical adsorption.