Assessment of localized and resuspended 137 Cs due to decontamination and demolition in the difficult-to-return zone of Tomioka town, Fukushima Prefecture.

Abstract

As the next step that occurred more than one decade after the accident at the Fukushima Dai-ichi Nuclear Power Station (FDNPS), decontamination and demolition have been carried out in the Specified Reconstruction and Revitalization Base (SRRB) of the difficult-to-return zone around the FDNPS. However, the risk of internal exposure among workers due to airborne dust inhalation after building demolition operations has not been sufficiently evaluated. To evaluate the working environment and internal exposure risk due to inhalation in the SRRB of Tomioka town, Fukushima Prefecture, the cesium-137 (137 Cs) radioactivity levels in the airborne dust at building demolition sites were analyzed using gamma spectrometry. The 137 Cs radioactivity levels and resuspension factors of the airborne dust at the subject building sites in the difficult-to-return zone remained at high levels compared with those of the control, which was located in the evacuation order-lifted area in Tomioka town. However, the 137 Cs radioactivity levels did not increase significantly, despite demolition operations that used heavy machinery. In this case, no substantial increases in accident-derived 137 Cs levels due to decontamination and demolition in the SRRB of Tomioka town, Fukushima Prefecture, were observed in the airborne dust samples, which suggests that the 137 Cs radioactivity in the airborne dust is primarily associated with particles that are resuspended by localized winds accompanied by the transfer of construction vehicles as opposed to the decontamination and demolition operations. However, the internal exposure doses due to aspirating airborne dust containing 137 Cs were extremely low compared with the estimated annual effective doses of decontamination workers or the limits recommended by the Japanese government. Additionally, countermeasures such as wearing protective masks could help reduce the on-site inhalation of soil-derived radionuclides. Integr Environ Assess Manag 2022;18:1555-1563. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).