Osama M. Farid

A novel and highly promising Ag ₂ S-P2MA nanoribbon photocathodes are synthesized using a single-step technique based on 2-mercaptoaniline oxidation with (NH ₄ ) ₂ S ₂ O ₈ and AgNO ₃ . This process yields polymer composites with nanoribbon morphologies, typically 150 nm wide and ranging from 500 to 1,000 nm in length. These nanoribbons exhibit excellent absorbance across the entire optical spectrum up to 780 nm. The fabricated Ag ₂ S/P2MA photocathode is designed for water splitting to generate hydrogen gas using two different electrolytes: natural Red Sea water and artificial seawater free from heavy metals. This variation allows observation of the impact of seawater’s heavy metals. Hydrogen gas production is studied using a three-electrode cell with linear sweep voltammetry at room temperature. In both electrolytes, the photocurrent is measured at 0.015 mA/cm ² . However, both the current density in light ( J _ph ) and dark ( J _o ) values decrease in artificial seawater compared to natural seawater, with values of −0.033 and −0.017 mA/cm ² in natural seawater and −0.027 and −0.012 mA/cm ² in artificial seawater. The Ag ₂ S-P2MA nanoribbon photocathodes exhibit stable behavior, producing hydrogen at a rate of 12 µmol/cm ² h. Combined with their cost-effectiveness and potential for mass production, this positions them as viable candidates for commercial electrode applications in various industrial settings.

Initial leaching characteristics of simulated nuclear waste immobilized in three alkali- borosilicate glasses (ABS-waste) were studied. The effects of matrix composition on the containment performance and degradation resistance measures were evaluated. Normalized release rates are in conformance with data reported in the literature. High Li and Mg loadings lead to the highest initial de-polymerization of sample ABS-waste (17) and contributed to its thermodynamic instability. Ca stabilizes non-bridging oxygen (NBO) and reduces the thermodynamic instability of the modified matrix. An exponential temporal change in the alteration thickness was noted for samples ABS-waste (17) and Modified Alkali-Borosilicate (MABS)-waste (20), whereas a linear temporal change was noted for sample ABS-waste (25). Leaching processes that contribute to the fractional release of all studied elements within the initial stage of glass corrosion were quantified and the main controlling leach process for each element was identified. As the waste loading increases, the contribution of the dissolution process to the overall fractional release of structural elements decreases by 43.44, 5.05, 38.07, and 52.99% for Si, B, Na, and Li respectively, and the presence of modifiers reduces this contribution for all the studied metalloids. The dissolution process plays an important role in controlling the release of Li and Cs, and this role is reduced by increasing the waste loading.

The effect of irradiation on the tribocorrosion behavior of 316L stainless steel alloy was investigated in 0.02 M Na₂SO₄ solution, using a ball-on-flat configuration, which was connected with a three electrode-chemical cell. The rubbing and irradiation track morphology were investigated using Scanning Electron Microscopy and profilometric measurements after rubbing and irradiation tests. The rubbing tests, in the presence or absence of irradiation, were performed under 20 N normal force using an alumina ball as a counter body. The surfaces were characterized through electrochemical measurements, optical microscopy, and elemental analysis while the corrosion phenomenon was examined by electrochemical impedance spectroscopy (EIS) and polarization potentiodynamic measurements. The open-circuit potential measurements and EIS measurements were used to evaluate the electrochemical reactivity of the 316L stainless steel surface before, during and after sliding tests. The corrosion rate was determined using the Tafel extrapolation technique. It was found that when the sample subjected to both tribo-corrosion and irradiation, the corrosion potential shifted more toward the anodic region and affects the corrosion kinetics. It is found that the surface of 316L stainless steel has a reasonable corrosion-irradiation resistance.

Verification of 235U enrichment in uranium hexaflouride (UF6) cylinders is often achieved by destructive and non-destructive assay techniques. These techniques are time consuming, need suitable and similar standard, in addition to loss of the nuclear material in the case of destructive analysis. This paper introduce an innovative approach for verifying of 235U enrichment in UF6 cylinder. The approach is based on measuring dose rate (μSv/h) resulted from the emmitted gamma rays of 235U at the surface of the cylinder and then calculating the activity of uranium and enrichment percentage inside the cylinder by a three dimensional model. Attenuation of the main 235U gamma transitions due to the cylinder wall (5A Type of Ni alloy) was also caculated and corrected for. The method was applied on UF6 cylinders enriched with 19.75% of 235U. The calculated enrichment was found to be 18% with 9% uncertainty. By the suggested method, the calculated total uranium activity inside one of the investigated UF6 cylinder was found close to the target (certified) value (5.6 GBq) with 9% uncertainty. The method is being developed by taking into consideration other parameters.