Particle size distribution of radioactive aerosols after the Fukushima and the Chernobyl accidents

Following the Fukushima accident, a series of aerosol samples were taken between 24th March and 13th April 2011 by cascade impactors in the Czech Republic to obtain the size distribution of I-131, Cs-134, Cs-137, and Be-7 aerosols. All distributions could be considered monomodal. The arithmetic means of the activity median aerodynamic diameters (AMADs) for artificial radionuclides and for Be-7 were 0.43 and 0.41 mu m with GDSs 3.6 and 3.0, respectively. The time course of the AMADs of Cs-134, Cs-137 and Be-7 in the sampled period showed a slight decrease at a significance level of 0.05, whereas the AMAD pertaining to I-131 increased at a significance level of 0.1. Results obtained after the Fukushima accident were compared with results obtained after the Chernobyl accident. The radionuclides released during the Chernobyl accident for which we determined the AMAD fell into two categories: refractory radionuclides (Ba-140, La-140 Ce-141, Ce-144, Zr-95 and Nb-95) and volatile radionuclides (Cs-134, Cs-137, Ru-103, Ru-106, I-131, and Te-132). The AMAD of the refractory radionuclides was approximately 3 times higher than the AMAD of the volatile radionuclides; nevertheless, the size distributions for volatile radionuclides having a mean AMAD value of 0.51 mu m were very close to the distributions after the Fukushima accident. (C) 2013 Elsevier Ltd. All rights reserved.