Air radioactivity levels following the Fukushima reactor accident measured at the Laboratoire Souterrain de Modane, France

The radioactivity levels in the air of the radionuclides released by the Fukushima accident were measured at the Laboratoire Souterrain de Modane, in the South-East of France, during the period 25 March-18 April 2011. Air-filters from the ventilation system exposed for one or two days were measured using low-background gamma-ray spectrometry. In this paper we present the activity concentrations obtained for the radionuclides I-131, Te-132, Cs-134, Cs-137, Nb-95, Zr-95, Ru-106, Ba-140/La and Ru-103. The activity concentration of I-131 was of the order of 100 mu Bq/m(3), more than 100 times higher than the activities of other fission products. The highest activities of I-131 were measured as a first peak on 30 March and a second peak on 3-4 April. The activity concentrations of Cs-134 and Cs-137 varied from 5 to 30 mu Bq/m(3). The highest activity concentration recorded for Cs corresponded to the same period as for I-131, with a peak on 2-3 April. The results of the radioactivity concentration levels in grass and mushrooms exposed to the air in the Modane region were also measured. Activity concentrations of I-131 of about 100 mBq/m(2) were found in grass. (C) 2012 Elsevier Ltd. All rights reserved.