Development of Continuous Monitoring System to Confirm the Behavior of Radioactive Substances in Forest of Fukushima.

Since the accident of nuclear power plant in Fukushima occurred in March 2011. Fukushima area is mountainous and there is high annual precipitation. Thus, it is concerned to move radioactive substances affected by soil erosion in forest. Regarding this problem, we have already developed a field monitoring system (FMS) with a radiation sensor and have been monitoring the radiation level in Iitate village in Fukushima since December 2011. However, we have not yet succeeded to monitor the continuous movement of radioactive substances along a stream line in forest. Therefore, we developed a wireless connection system to support the monitoring along the stream line. We set FMS with a radiation sensor and set a soil collector, a radiation logger, and a wireless connection system below 30m from upstream. Since the wireless device in downstream communicates to the FMS in upstream, data of multiple locations can be collected automatically in quasi real time by a FMS. We believe the wireless connection system will be a powerful tool to monitor the moving of radioactive substances affected by soil erosion in forest.