RESUMO
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.
RESUMO
Following accidental releases, gamma spectrometry of impregnated charcoal filters is used to measure gaseous 131I contamination, but is subject to sampling inhomogeneity. In this study two germanium detectors are calibrated using a charcoal multi-gamma standard. Activities in samples spiked with a matrix of 131I aliquots are compared based on measurement, spike known activity, and monte-carlo simulation, and used to test a simple mixing method. Measurement efficiency, and removal of 11% inhomogeneity effect by mixing, was successfully reproduced in GESPECOR calculations.
RESUMO
We describe the development of an automated, user-friendly programme which, making use of the GESPECOR gamma spectrometry software to conduct Monte Carlo simulations, yields an optimised model of a HPGe detector by applying suitable optimisation algorithms without requiring any further user intervention. The programme is capable of simultaneously employing multiple experimental FEP efficiency curves for the parameter optimisation process. Application of the optimisation process to a HPGe detector demonstrates that accurate, robust models can be achieved using this approach.