A presence of106Ru radionuclide was incidentally observed during the first days of October by most European laboratories engaged in measuring the ambient atmosphere radioactivity. On October 03, 2017, traces of this isotope were identified in the BEO-Moussala as well. After a routine air sampling procedure, the gamma-ray spectrum of the sample was acquired using an H.P.Ge spectrometer. The activity of106Ru was determined using the most intensive gamma-lines of106Rh, 511.8 keV, 621.8 keV and 1060.4 keV, observed in the spectrum. Thus, the calculated activity of106Ru in the sample from October 03, 2017 was 1.75 mBq/m3 . The analysis of the wind rose for the period October 01÷05, 2017, revealed that the wind was predominantly northerly, with a weaker northeastern component.
In the lack of officially recognized evidences, one can assume that the release of106Ru in the atmosphere was most likely a result of an accident in a factory producing this isotope. The quantity of the measured radioactivity spread in the air however, was hundreds of times lower than the permissible activity limits for this isotope; no risk existed of health problems for the population and for the ecosystems.
Key words: aerosol activity,106Ru, gamma-spectrometry, accident
Topic: PHYSICS