Occurrence of radioactive cesium-rich micro-particles (CsMPs) in a school building located 2.8 km south-west of the Fukushima Daiichi Nuclear Power Plant
Journal
Chemosphere
Journal Volume
328
Start Page
138566
ISSN
0045-6535
Date Issued
2023-07
Author(s)
Fueda, Kazuki
Komiya, Tatsuki
Minomo, Kenta
Horie, Kenji
Takehara, Mami
Yamasaki, Shinya
Shiotsu, Hiroyuki
Ohnuki, Toshihiko
Grambow, Bernd
Law, GarethT.W.
Ewing, RodneyC.
Abstract
Radioactive Cs-rich microparticles (CsMPs) released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) are a potential health risk through inhalation. Little has been documented on the occurrence of CsMPs, particularly their occurrence inside buildings. In this study, we quantitatively analyze the distribution and number of CsMPs in indoor dust samples collected from an elementary school located 2.8 km to the southwest of FDNPP. The school had remained deserted until 2016. Then, using a modified version of the autoradiography-based “quantifying CsMPs (mQCP) method,” we collected samples and determined the number of CsMPs and Cs radioactive fraction (RF) values of the microparticles (defined as total Cs activity from CsMPs/bulk Cs activity of the entire sample). The numbers of CsMPs ranged from 653 to 2570 particles/(g dust) and 296–1273 particles/(g dust) on the first and second floors of the school, respectively. The corresponding RFs ranged between 6.85 – 38.9% and 4.48–6.61%, respectively. The number of CsMPs and RF values in additional outdoor samples collected near the school building were 23–63 particles/(g dust or soil) and 1.14–1.61%, respectively. The CsMPs were most abundant on the school's first floor near to the entrance, and the relative abundance was higher near the stairs on the second floor, indicating a likely CsMP dispersion path through the building. Additional wetting of the indoor samples combined with autoradiography revealed that indoor dusts had a distinct absence of intrinsic, soluble Cs species, such as CsOH. These combined observations indicate that a significant amount of poorly soluble CsMPs were likely contained in initial radioactive airmass plumes from the FDNPP and that the microparticles penetrated buildings. CsMPs could still be abundant at the location, with locally high Cs activity in indoor environments near to openings.
Subjects
Cesium-rich microparticles
Fukushima Daiichi
Indoor environment
Radioactive cesium
Transmission electron microscopy
Publisher
Elsevier BV
Type
journal article