Individual external dose monitoring of all citizens of Date City by passive dosimeter 5 to 51 months after the Fukushima NPP accident (series): 1. Comparison of individual dose with ambient dose rate monitored by aircraft surveys

Makoto Miyazaki,Ryugo Hayano

doi:10.1088/1361-6498/37/1/1

Abstract

Date (da’te) City in Fukushima Prefecture has conducted a population-wide individual dose monitoring program after the Fukushima Daiichi Nuclear Power Plant Accident, which provides a unique and comprehensive data set of the individual doses of citizens. The purpose of this paper, the first in the series, is to establish a method for estimating effective doses based on the available ambient dose rate survey data. We thus examined the relationship between the individual external doses and the corresponding ambient doses assessed from airborne surveys. The results show that the individual doses were about 0.15 times the ambient doses, the coefficient of 0.15 being a factor of 4 smaller than the value employed by the Japanese government, throughout the period of the airborne surveys used. The method obtained in this study could aid in the prediction of individual doses in the early phase of future radiological accidents involving large-scale contamination.

Highlights

In making decisions regarding appropriate protection policy against radioactive contamination after nuclear accidents, obtaining the individual dose distribution is crucial
The ICRP recommends [1, 2] the responsible bodies to characterize the individual dose distribution of the exposed population, and to take appropriate and optimized actions based on the ALARA principle
After the summer of 2011, many Fukushima municipalities started individual external dose monitoring for members of the public living in existing exposure situations, such largescale measurements of the general public have not been considered mandatory in the conventional radiation protection schemes

Summary

Introduction

In making decisions regarding appropriate protection policy against radioactive contamination after nuclear accidents (such as the Fukushima Daiichi Nuclear Power Plant: FDNPP accident), obtaining the individual dose distribution is crucial. After the summer of 2011, many Fukushima municipalities started individual external dose monitoring for members of the public living in existing exposure situations, such largescale measurements of the general public have not been considered mandatory in the conventional radiation protection schemes. These municipal dose measurement programs were not initiated nor supervised by the Japanese central government, and they were not standardized in terms of the target group, distribution/collection methods, the format of data dissemination, and instructions describing how the dosimeters should be used. The collected data have not been well utilized for the benefit of the affected communities

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Discussion

Conclusion