Abstract
The external and internal radiation doses were estimated for 15 residents who lived at around 37 km north-west from the Fukushima Daiichi nuclear power plant which released radioactive plume due to the accident on March 11, 2011. An interview has been performed to ask where they stayed and what they ate after the accident. To estimate the external radiation dose for each person, the air dose rate at the person's yard was measured and cumulative dose up to the 54th day from the release has been calculated. With regard to the internal radiation dose, urinary bioassay method has been performed on the 54th day and the 78-85th day after the deposition, by using a low-background Ge spectrometer. As a result, the average external dose was 10.5mSv among the adults, and 6.3mSv among the children. The average committed effective dose from <134>Cs and <137>Cs was 0.055mSv among the adults and 0.034mSv among the children. <131>I was detected in five persons; four adults and one child. The average committed effective dose from <131>I was 2.5mSv among the adults and 2.2mSv of the child. The ratio of external dose to internal dose from <134>Cs and <137>Cs ranged from 87:1 to 566:1 among them.
