Dose estimation in recycling of decontamination soil from the fukushima daiichi nps accident for land reclamation

Recycling of decontamination soil from the Fukushima Daiichi Nuclear Power Station after the 2011 accident for land reclamation is effective for reducing the amount of decontamination soil that must be disposed. In the present study, dose estimation for workers and the public was conducted from the viewpoint of application of recycling material to land reclamation by considering exposure pathways from the construction to the servicing of the land as a greenery-covered area. From the results, the concentration level of radiocesium, 134Cs and 137Cs, for which the annual effective exposure dose does not exceed 1 mSv/y was calculated. In addition, the thickness of the cover soil required to maintain the exposure dose lower than 10 μSv/y for the public during servicing was ascertained. Furthermore, disasters were considered; for instance, by considering that tsunamis, fires, and concentrated heavy rain can increase exposure doses based on changes in the conditions of the reclamation land, we confirmed that the additional exposure dose during disaster and rehabilitation is lower than 1 mSv/y. Based on these evaluation results, we determined concentration levels amenable to recycling.