Airborne concentrations and chemical considerations of radioactive ruthenium from an undeclared major nuclear release in 2017.

In October 2017, most European countries reported unique atmospheric detections of aerosol-bound radioruthenium (106Ru). The range of concentrations varied from some tenths of µBq·m-3 to more than 150 mBq·m-3 The widespread detection at such considerable (yet innocuous) levels suggested a considerable release. To compare activity reports of airborne 106Ru with different sampling periods, concentrations were reconstructed based on the most probable plume presence duration at each location. Based on airborne concentration spreading and chemical considerations, it is possible to assume that the release occurred in the Southern Urals region (Russian Federation). The 106Ru age was estimated to be about 2 years. It exhibited highly soluble and less soluble fractions in aqueous media, high radiopurity (lack of concomitant radionuclides), and volatility between 700 and 1,000 °C, thus suggesting a release at an advanced stage in the reprocessing of nuclear fuel. The amount and isotopic characteristics of the radioruthenium release may indicate a context with the production of a large 144Ce source for a neutrino experiment.

Study of the surface character as responsible for controlling interfacial forces at membrane-feed interface.

The role of the interfacial forces was emphasized in interactive processes, involving membrane surface and penetrating molecules. The surface character controlling the dissolution process of some species (CO2, H2O, C3H6O2, C4H8O2, C5H10O2) was evaluated in relation to the supra-molecular chemistry of membranes based on 80PTMO/PA12. Infrared analyses combined with the estimation of the hydrophilic and hydrophobic domains of the membrane surface yielded useful information about the distribution, availability and accessibility of the polar moieties responsible for the penetrant sorption. At the interface, attractive Lewis acid/base interactions such as H-bonding directed the sorption of vapor species into the membranes, whereas quadrupolar CO2 participated in specific Lifshitz-van der Waals interactions with the modified polymers. In both the cases, the presence of additional polar moieties such as carbonyl, sulfonamide, and hydroxyl groups enhanced the affinity of the Pebax-based membranes for the penetrating species considered in this work. As a result, the quantification of the reactivity of a membrane surface for specific molecules may allow predictive models to be constructed and selective membranes to be designed.