Anthropogenic Radionuclides in Environmental Samples from Fukushima Prefecture

Four environmental samples from Fukushima prefecture, taken in March 2012, were analysed with gamma and alpha spectrometry. The aim was determining radionuclide ratios. The estimated ratio of Cs / Cs equals 1.062, with standard deviation (indicating variability between samples) 0.024. The ratio seems to be somewhat higher than what is mostly reported in the literature, namely between <0.9 and about 1. The only other long-lived gamma radionuclide which could be identified is 110mAg, whose ratio to 137Cs equals (2.3 ± 0.2) 10-3. The ratios of 239+240Pu and Cs in Fukushima fallout are below 10, calculated under the assumption that the only Pu sources are global and Fukushima fallout. More samples would be needed to improve the statistical reliability of the results, and to investigate the reason for the found slight discrepancy of Cs ratios with those reported in literature.