Study on precision improvement of aircraft radiation monitoring

Since the reactor accident of Fukushima Daiichi Nuclear Power Station, development of environmental radiation monitoring that can quickly measure large areas is required. JAEA is conducting an airplane monitoring with large detectors for gamma rays (NAI) on a helicopter and measures the count rate at many measuring points, corrects for the influence of factors such as altitude and converts the data into air dose rates at 1 m above the ground level. The present work aims precision improvement by employing evaluation model for dose rate contribution from each radioactivity attached to the sampling materials such as the dusts, water, the undergrowth, the soils, and the leaves of the trees in the forests and the fields. By comparing the evaluated air dose rate using the present model and the measured value, the validity of the method has been confirmed. (S. Ohno)