Volume 112, Issue 10

Radionuclide migration is an essential process in the performance and safety assessments of radioactive waste repository. This study investigates uranium migration in Beishan granite using the continuous column method, focusing on the effects of flow rate, eluent pH, and carbonate. Experimental parameters were used to perform COMSOL simulations of the migration process. The findings reveal that mechanical dispersion plays a predominant role in uranium migration in the granite column. Notably, the impact of adsorption on migration appears to be limited, likely due to the brief contact time in the experimental setup. The study successfully demonstrates the capability of COMSOL in simulating radionuclide migration, offering significant insights for the performance and safety assessments of repository.

This paper reports the studies carried out on the development of a process for the recovery of 1,3-dioctyloxycalix[4]arene-18-crown-6 (CC-6) from the spent solvent generated during industrial scale separation of 137 Cs from High Level Liquid Waste (HLLW). Initial works involved the validation of a conceptual process design and optimization of the process parameters with a simulated solvent. The optimized process was then tested with actual spent solvent to recover calix-crown-6. Such a process to recover undegraded and potentially re-usable calix-crown-6 from the spent solvent has been attempted for the first time with the aim of value recovery and reduced spent solvent management burden.

A novel SiO 2 /Al 2 O 3 /poly(acrylic acid-co-glycidyl methacrylate), SiO 2 /Al 2 O 3 /P(AA-co-GMA), composite was synthesized and evaluated for its effectiveness in adsorbing Co(II) ions from aqueous solutions. The composite was analyzed using various techniques including FTIR, SEM, TGA, DTA, and XRD. The composite displays a high specific surface area of 17.451 m 2 /g, exceeding that of the corresponding copolymer, which measures 0.236 m 2 /g. Batch adsorption experiments were conducted to investigate the factors influencing the adsorption capacity of the composite for Co(II) ions. In the pH experiments, it was found that at a solution pH of 3.4, the P(AA-co-GMA) copolymer alone showed limited capability in adsorbing Co(II) ions, achieving only 3.82 mg/g. However, upon integration of SiO 2 /Al 2 O 3 into the polymer matrix, the composite exhibited a significantly enhanced adsorption capacity of 103.54 mg/g. The adsorption process followed a pseudo-second-order kinetic model and attained equilibrium within 60 min. The Langmuir isotherm model was found to best describe the adsorption behavior, with a maximum adsorption capacity of 217.86 mg/g. The adsorption of Co(II) was significantly affected by the ionic strength, especially with Al 3+ displaying a more pronounced impact on the adsorption of Co(II) ions compared to Na + , Ca 2+ , and Mg 2+ . Thermodynamic studies indicate that the adsorption process was spontaneous and endothermic. Overall, the SiO 2 /Al 2 O 3 /P(AA-co-GMA) composite material displayed significant adsorption ability for Co(II) ions, making it a suitable option for further development as an effective adsorbent in water treatment applications.

Monitoring radioactivity around nuclear power plants is important to avoid the risks of radiation. This study provides an overview of the radioactive emission impact on the near surroundings of the Metsamor nuclear power plant in Armenia. In this context, 29 soil samples were collected from the 40, 80, 120, 160 km radius areas determined in the direction of Iğdır province by accepting the Metsamor nuclear power plant as the center. The activity concentrations of 226 Ra, 232 Th, 40 K and 137 Cs in soil samples ranged from 7.90 to 23.44, 7.11 to 33.55, 132.54 to 502.69 and 0.33 to 17.61 Bq/kg, respectively. In addition, the radioactivity concentrations in some agricultural products and the transfer factors from soil to plant were determined. As a result, there is no significant radiological risk in terms of studied radioisotopes for people living in this region.

In order to contribute to the sufficient supply of clinical 99m Tc(VII), the sorption behavior of neutron-produced 99 Mo(VI) was investigated on synthetized single and binary Ti and Zr xerogels treated at different temperatures, under normal operating conditions. Materials were prepared by the sol–gel method and characterized by several techniques. Sorption batch systems were performed using 99 Mo radiotracer to determine the metallic affinity as a function of pH, and a methodology was developed in order to obtain the maximum capacities by surface saturation, where the Ti-388, TiZr-388 (3:1) and Zr-388 samples showed the most noteworthy sorption behaviors (33.1 ± 0.34 mg/g at pH ∼ 6.0, 31.7 ± 0.27 mg/g at pH ∼ 6.5, and 23.5 ± 0.61 mg/g at pH ∼ 6.8, respectively). The molybdenum-99 sorption behavior was also studied by fitting to the Freundlich and Langmuir models, and all xerogels could be described as heterogeneous materials with favorable 99 Mo sorption properties. Finally, preliminary studies of clinical-scale 99 Mo/ 99m Tc generators were performed, the results revealed the next maximum 99m Tc elution yield order Ti-388 (89.6 %) > TiZr-388 (3:1) (86.7 %) > Zr-388 (77.7 %).

This study represents the investigation of major and trace elements in two indigenous plants, Cynodon dactylon (L.) and Phragmites australis , grown in the Ghardaia region of Southern Algeria. Using Instrumental Neutron Activation Analysis (INAA) technique, the research aimed to ascertain the content of essential and toxic elements in the aerial parts of these plants. Twenty eight elements as (Ag, As, Ba, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, Hg, K, La, Lu, Na, Nd, Rb, Sb, Sc, Se, Sm, Sr, Tb, Th, Yb and Zn) were analysis with INAA method. Given the scarcity of data regarding essential and toxic chemical elements in food within Algeria, the study focused on evaluating the content of these elements in two plant species commonly utilized by Bedouins in traditional medicine and as fodder, as well as by professionals for decontamination and water purification purposes. The concentrations of mineral elements observed in these plants were found to be in proximity to the minimum levels recommended by the Food and Agriculture Organization (FAO). The data obtained from this investigation are deemed applicable for Algerian food purposes, offering valuable insights into the elemental composition of these plants and their potential roles in traditional and practical applications.

The residence time distribution (RTD) is very reliable, providing valuable information about the performance of process equipment such as reactors and columns. The aim of this work is to study the effect of agitation in the hydrodynamic column of flow-rig. In this case, residence time distribution (RTD) is determined using the radiotracer approach. The radiotracer is the Technetium Tc-99m with half decay 6 h. It also emits gamma rays with an energy of 0.140 MeV. 2 mL of approximately 9 mCi activity Tc-99m was injected inside the column. The results show that in the conditions studied the column presents the anomaly, dead volume. The Intensity function A ( t ) confirms this result. Agitation has a beneficial effect in the reduction of dead volume. To revise the conception of the column or study other parameters like the variation flow rate can reduce or eliminate the dead volume. The RTD model indicated the column behaved as a Plug flow reactor (PFR) with mixing cells in serie ( J  = 4) model and the RTD experiment verified the model well.

In this study, the activity concentration of artificial and natural radionuclides such as 137 Cs, 40 K, 226 Ra, and 232 Th was measured in the soil under the roots; leaves; and fruits of six different fruit trees namely mulberry, fig, apricot, olive, black and white grapes in Koya district, Erbil province, Iraq. For this purpose, a high-resolution gamma spectroscopy consisting of a high-purity germanium (HPGe) detector was used. In addition, the associated radiological risks from soil and fruits were assessed by calculating several radiological indices such as radium equivalent (Raeq.s), absorbed dose (Ds), indoor ( AEDEs indoor ) and outdoor annual effective doses ( AEDEs outdoor ), internal and external hazard indices, gamma index and the excess lifetime cancer risk (ELRCs). The results show that consuming these fruits is radiologically safe because they can cause an annual effective dose of about 61.72 μSv y −1 and excess lifetime cancer risk of 0.06 × 10 −3  Sv y −1 . On the other hand, transfer factors of radionuclides from soil to leaves; and from soil to fruits were studied. The transfer factor analysis revealed that among the studied fruits and radionuclides, apricot and mulberry exhibited the highest transfer factors for 40 K, with values of 1.85 and 1.87, respectively.

The current work seeks to develop a novel CuO-doped lead calcium barium borate glass using the melt quenching method at 1100 °C. There was a 3.91–4.49 g/cm 3 change in the fabricated glasses’ density, with a respective 0–15 mol.% increase in the CuO concentration. Additionally, substituting CuO for B 2 O 3 reduced the fabricated glasses mechanical properties due to the decreased dissociation energy between 63.99 and 60.50 kcal/cm 3 , and the packing factor decreased between 15.22 and 13.23 cm 3 /mol. Through increasing the fabricated glasses’ CuO concentration, there was a decrease in the bulk, longitudinal, shear, and mechanical Young moduli. Moreover, Monte Carlo simulation (energy interval: 0.033–2.506 MeV) was employed to evaluate the fabricated glasses’ ability to shield gamma rays. A 0–15 mol.% increase in the CuO concentration raised the linear attenuation coefficient (LAC) between 14.081 and 16.797 cm −1 (0.059 MeV), 0.325–0.371 cm −1 (0.662 MeV), and 0.154–0.176 cm −1 (2.506 MeV). The LAC enhancement reduced the required half value thickness of the fabricated glasses by 16.2 %, 12.53 %, and 12.85 % at the of 0.059, 0.662, and 2.506 MeV gamma ray energies.