The distribution of radiotoxic 137Cs concentrations in seaweed and mussel species in the Mediterranean Sea.

A study was conducted to determine the 137Cs activity concentrations in various seaweed and mussel samples from the North East Mediterranean Sea, including the brown algae (Dictyota dichotoma) and oarweed (Laminaria digitata), and mussel species (Haliotis asinina, Mytilus edulis and Mytilus galloprovinciali). The 137Cs activity concentration in seaweed species exhibited varying levels, ranging from 84.20 ± 1.82 to 236.05 ± 5.72 mBq kg-1 fresh weight (fw) for oarweed, and 106.29 ± 2.26 to 252.38 ± 6.04 mBq kg-1 fw for brown algae. The 137Cs value in mussel species were between 12.94 ± 0.51-101.84 ± 1.35 mBq kg-1 fw for M. galloprovincialis, 15.49 ± 0.58-71.52 ± 1.16 mBq kg-1 fw for M. edulis, and 10.36 ± 0.11-69.13 ± 1.34 mBq kg-1 fw for H. asinine. When comparing the 137Cs concentration in seaweed and mussel species, the average concentration in seaweeds was approximately four times higher than that in mussels. This significant difference in radioisotope concentration highlights the potential for higher bioaccumulation of 137Cs in seaweeds compared to mussels.

Radiotoxic fission products and radiological effects in the Mediterranean Sea biota from a hypothetical accident in Akkuyu Nuclear Power Plant.

A combined hydrodynamic/radiobiological model was used to calculate the distribution and dose rate of significant radionuclides in the Mediterranean Sea marine organisms in the event of an accident at the Akkuyu Nuclear Power Plant (ANPP). The Hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model was applied to simulate the dispersion and deposition of artificial radionuclide concentrations. Environmental Risk from Ionising Contaminants: Assessment and Management (ERICA) tools were utilized to assess issues related to sea health and potential hazards in case of an accident. The scenario source term profile was derived from the Fukushima nuclear power accident. Volumetric concentrations and deposition levels of pollutants increased from 1 MBqm-3 to 1 × 103 MBqm-3 and from 1 × 10-1 MBqm-2 to 1 × 10-7 MBqm-2 after 48 h. In terms of dose rates to the various marine biotas, polychaete worms had the greatest overall dose rate and the highest contribution to total dose rates attributable to 137Cs radionuclide.

Shielding Properties of Epoxy Matrix Composites Reinforced with MgO Micro- and Nanoparticles.

The aim of the current study is to investigate the impact of introducing micro- and nanoparticle MgO as a filler into epoxy resin on the radiation shielding abilities of the prepared samples. To this end, we performed a gamma-radiation spectroscopy experiment with the help of an HPGe detector and Am-241, Cs-137, and Co-60 sources. We evaluated the particle size effect (PSE) and detected the maximum PSE value with the addition of 50 wt% MgO particles, indicating that nanoparticle MgO was more successful in shielding against incoming radiation than microparticle MgO. We compared the half-value layer (HVL) for the samples with 10 wt%, 20 wt%, and 30 wt % micro-MgO and nano-MgO and found that the HVL values were lower for the nanoparticle samples than for the microparticles samples, confirming that smaller particle sizes enhanced the shielding ability of the samples against radiation. The MFP results showed that epoxy matrices containing micro-MgO, for all investigated energies, resulted in higher MFP values that those containing nano-MgO.

Temperature-Driven Transformation of the Crystal and Magnetic Structures of BiFe0.7Mn0.3O3 Ceramics.

The compound BiFe0.7Mn0.3O3 consisting at room temperature of coexistent anti-polar orthorhombic and polar rhombohedral phases has a metastable structural state, which has been studied by laboratory X-ray, synchrotron and neutron diffraction, magnetometry, differential thermal analysis, and differential scanning calorimetry. Thermal annealing of the sample at temperatures above the temperature-driven phase transition into the single phase rhombohedral structure (~700 K) causes an increase of the volume fraction of the rhombohedral phase at room temperature from ~10% up to ~30%, which is accompanied by the modification of the magnetic state, leading to strengthening of a ferromagnetic component. A strong external magnetic field (~5 T) applied to the sample notably changes its magnetic properties, as well as provides a reinforcement of the ferromagnetic component, thus leading to an interaction between two magnetic subsystems formed by the antiferromagnetic matrix with non-collinear alignment of magnetic moments and the nanoscale ferromagnetic clusters coexisting within it. The modification of the structural state and magnetic properties of the compounds and a correlation between different structural and magnetic phases are discussed focusing on the effect of thermal annealing and the impact of an external magnetic field.

Green Conversion of the Hazardous Cathode Ray Tube and Red Mud into Radiation Shielding Concrete.

The present investigation was aimed at the utilization of alternate materials, emphasizing hazardous industrial products (red mud and cathode ray tubes), as constituents of radiation shielding concrete. The usage of these hazardous industrial products improves the sustainability and performance of the radiation shielding concrete. Five concrete blocks were cast and their density, compressive strength, gamma shielding factors, radiation absorption ratio, and transmission factor were explored. For this purpose, gamma-ray shielding measurements were done with the help of an HPGe detector. Mix-1, with zero contents of red mud and CRTs, had the lowest LAC. The LAC results demonstrated that the shielding performance of the current concretes would be better with the increase in red mud and cathode ray tube glass. The Transmission factor (TF) for the prepared concretes with a thickness of 2 cm varied between 11.9-26.1% at 0.06 MeV, while it varied between 4-13% for a thickness of 3 cm. The TF results showed that the composites with a thickness of 2, 3, or 5 cm are good shields against lower energy radiation. The radiation absorption ratio (RAR) for the prepared concretes is high at low energy, suggesting that these new composites can absorb most of the low-energy photons. The RAR results emphasize that the increase in CRTs in the new composites enhanced the radiation shielding features, and when the CRT glass is at a maximum, more attenuation was achieved.

Thermoluminescence dosimetric attributes of Yb3+ -doped BaO-ZnO-LiF-B2 O3 glass material after Er3+ co-doping.

Motivated by our previous study on Sm3+ ions as thermoluminescence (TL) sensitizers to the BaO-ZnO-LiF-B2 O3 -Yb2 O3 glass system, in the current study we examined the effect of Er3+ ion co-doping on the TL characteristics of this glass system. The 4f-4f electronic transitions of the Er3+ and Yb3+ ions were confirmed via the optical absorption spectrum. Notably, the use of Yb3+ -Er3+ ions failed to improve the TL intensity, sensitivity, and trap density. However, they enabled the glass system to function as an activator-quencher system. The linearity range and effective atomic number remained unaffected after co-doping. In addition, the problem of anomalous fading caused a remnant signal of just 58% after a week of storage of the Yb3+ monodoped glass. This was resolved by the optimum co-doping of Er3+ ions to achieve an 89% signal. The co-doping of Er3+ ions to the BaO-ZnO-LiF-B2 O3 -Yb2 O3 glass system regulated its thermal stability and therefore supplemented its potential for radiation monitoring in food processing and retrospective dosimetry.