Comparison of the Fukushima radioactive mapping by two different aerial radiation monitoring systems

A radiation monitoring system using unmanned aerial vehicles (UAVs) was developed for post-nuclear accidents by the Korea Institute of Nuclear Safety (KINS). The Japan Atomic Energy Agency (JAEA) has been conducted radiation monitoring in the Fukushima area and undertaking research and development of related technology. Considering future large-scale disasters, it is important that measurement methods using UAVs are unified between the neighbor countries. Two organizations in neighbor countries attempted technical collaborations to compare results obtained from different methods. In 2015, measurements were carried out in an area within 10 km from the Fukushima Dai-ichi Nuclear Power Station (FDNPS), where an accident occurred due to the Great East Japan Earthquake and where contamination remains and access is controlled. Corrections to convert the coefficients from detectors in air to the radiation dose or radioactivity concentration on the surface were carried out in areas previously surveyed as flat and relatively evenly contaminated. Explorations of contamination mapping were conducted in river basins, with contaminants appearing in different water and soil contours, which were expected to make intuitive comparisons easier for multiple mappings. We used a Japanese unmanned helicopter, which is used for agricultural applications such as the spraying of pesticides. The measurement system of JAEA and KINS was installed and the same route was flown once in each case.