Abstract
Large releases of radionuclides from the Fukushima Daiichi Nuclear Power Plant have resulted in serious radioactive pollution of a wide region of Eastern Japan. Air dose rates throughout Iwate Prefecture were measured with hand-held dosimeter from June 1 to July 2, 2011. The maximum value by the travel survey method (0.24 µSv/h) was observed at Maesawa Ward, Oshu City in June 2, 2011. The maximum value by soil surface measurement (0.45 µSv/h) was observed at Maesawa Ward, Oshu City in June 5, 2011. Contour maps of air dose rates were made with collected data. “Hot spot” was seen at the boundary area of Ichinoseki City, Oshu City and Hiraizumi Town. These distribution patterns corresponded to the results of airborne monitoring results of radiation dose by MEXT. These results indicate that distribution patterns of air dose rate would be estimated by travel survey and soil surface measurement with reliable hand-held commercial dosimeter. Air dose rates derived from fallout radioactive cesium at 30 years after the accident were predicted to be 13.5% of initial dose rates.
