In October 2017, most European countries reported unique atmospheric detections of aerosol-bound radioruthenium (Ru-106). The range of concentrations varied from some tenths of mu Bq.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 Ru-106 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 Ru-106 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 degrees 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 Ce-144 source for a neutrino experiment.