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[MAG24-P01] Radioactive particles in residual soil after strong acid leaching
Keywords: Radioactive particle, Silicate compound, Acid resistance
Soil sample was collected at the Motomiya city, Fukushima Prefecture, located of 40 km west from the F1NPP in October 2012. Concentration of 137Cs in soil was 8 kBq/kg (In March 11, 2011). Sequential extraction was performed (Five fraction was obtained, 1) water dissolve, 2) cation exchangeable, 3) organic form, 4) concentrated acid leachable, 5) residue.), and approximately 50% of 137Cs was remained in soil. Several number of spot type contamination were detected with autoradiography using an imaging plate. A spot was isolated from soil, and it was spherical particle. Constitution elements are Fe, Zn, Si, O, as well as Cs, which was detected using an energy dispersive X-ray spectrometry. These features are very similar to Cs-bearing radioactive particles isolated from air dust filter collected at the Tsukuba city by Adachi et al. (2013) and Abe et al. (2014). Therefore the particles distributed widely. In addition, dominant composition of particle is silicate of approximately 80 %. This result is consistent with Satou et al. (2015) and Yamaguchi et al. (2016). A silicate usually indicates acid resistance. These results suggested that the particulate form radiocesium is stable in environment, and it could be not remove by acid chemical treatment.