A Probabilistic Approach to Assess External Doses to the Public Considering Spatial Variability of Radioactive Contamination and Interpopulation Differences in Behavior Pattern

Abstract

Dose assessment is an important issue from the viewpoints of protecting people from radiation exposure and managing postaccident situations adequately. However, the radiation doses received by people cannot be determined with complete accuracy because of the uncertainties and the variability associated with any process of defining individual characteristics and in the dose assessment process itself. In this study, a dose assessment model was developed based on measurements and surveys of individual doses and relevant contributors (i.e., ambient dose rates and behavior patterns) in Fukushima City for four population groups: Fukushima City Office staff, Senior Citizens' Club, Contractors' Association, and Agricultural Cooperative. In addition, probabilistic assessments were performed for these population groups by considering the spatial variability of contamination and interpopulation differences resulting from behavior patterns. As a result of comparison with the actual measurements, the assessment results for participants from the Fukushima City Office agreed with the measured values, thereby validating the model and the approach. Although the assessment results obtained for the Senior Citizens' Club and the Agricultural Cooperative differ partly from the measured values, by addressing further considerations in terms of dose reduction effects due to decontamination and the impact of additional exposure sources in agricultural fields, these results can be improved. By contrast, the measurements obtained for the participants from the Contractors' Association were not reproduced well in the present study. To assess the doses to this group, further investigations of association members' work activities and the related dose reduction effects are needed.

Individual Doses to the Public after the Fukushima Nuclear Accident

“…Dose estimation based on some typical behavior patterns by age group or occupation could give a more realistic dose than that estimated using a fixed pattern like 8 hours outdoors and 16 hours indoors. Takahara et al [18,19] investigated behavior patterns for four population groups: Fukushi-JRPR ma City Office staff, senior citizens' club members, contractors' association members, and agricultural cooperative members. Then, probabilistic dose assessments were made for these population groups by considering the spatial variability of ambient dose rate and interpopulation differences resulting from behavior patterns.…”

Advances in Spatial Risk Analysis

“…The dose received by any population group predicts its risk of cancer. In their empirical study, Takahara, Iijima, Yoneda, and Shimada () compare estimates of the dose actually received by four population groups after the Daiichi Fukushima Disaster with the predictions made at the time of the accident.…”

“…Schneeberger et al (2019) and Terti et al (2019) develop probabilistic models for flood events. Takahara et al (2019) develop a probabilistic model for radiation dose assessment.…”