Monitoring radionuclides in the atmosphere over the Czech Republic after the Fukushima nuclear power plant accident

This paper presents the results of atmospheric radioactivity monitoring over the Czech Republic, as obtained by the Radiation Monitoring Network, following the Fukushima Dai-Ichi Nuclear Power Plant accident. Maximum values for 131I were 5.6 mBq m-3 in aerosol form and 13 mBq m-3 in gaseous form. The maximum values for 134Cs and 137Cs were 0.64 and 0.72 mBq m-3, respectively. The estimated effective half-time for removing the activity from the atmosphere was 6 -7 d and 3.5 d for caesium and iodine, respectively. The gaseous-to-total activity ratios of 131I ranged between 0.3 and 0.9, with an arithmetic mean value of 0.77. The mean value for the 134Cs/137Cs ratios was close to 1.0. The effective inhalation dose due to the accident for an adult living in the Czech Republic was estimated at <4 x 10-5 mSv, out of which the proportion of 131I was 88 %. (authors)