Evaluation of external dose exposure of workers during house demolition and dose reduction work in a difficult-to-return zone

Since the accident at the Fukushima Daiichi Nuclear Power Plant, many decontamination works have been carried out. Although the exposure status of decontamination workers has been appropriately managed by the government, there are few examples of detailed analysis of external dose exposure conditions. In this study, on the basis of the GPS location information obtained from GPS devices carried by the workers together with their personal dosimeters, the air dose rate in the work area and the characteristics of each type of work were analyzed. The results showed that more than 50% of the measured actual exposure doses were more than twice the median planned exposure dose calculated from the air dose rate and the number of actual working hours. Furthermore, the analysis by work type showed that demolition workers tended to have higher exposure doses. Such information on workers' external exposure doses linked to location information is useful for a detailed analysis of external exposure factors. Such an analysis also contributes to the optimization of future radiation protection programs for workers. (author)