LOCAL LEVELS OF RADIATION EXPOSURE DOSES DUE TO RADIOCESIUM FOR RETURNED RESIDENTS IN TOMIOKA TOWN, FUKUSHIMA PREFECTURE.

Abstract

Tomioka Town is located within a 20-km radius of the Fukushima Daiichi Nuclear Power Station. Radiation dose rates due to radiocesium in residents' living spaces were evaluated from the measurements of ambient dose rates and environmental samples after returning home. The mean ambient dose rates were 0.15-0.18-μSv/h indoors and 0.23-0.26-μSv/h outdoors during 2018 and 2019, and the additional radiation dose rates were calculated to be 1.4 mSv/y in 2018 and 1.1 mSv/y in 2019. Ambient dose equivalent from surface soils within housing sites were estimated to be 0.66 mSv/y in 2018 and 0.54 mSv/y in 2019. Moreover, committed effective doses from local foods were calculated in 19-74 μSv/y for children and 39-100 μSv/y for adults during 2018 and 2019. These findings suggest that current radiation exposure doses have been controlled at the levels close to the public dose limit (1 mSv/y) in residents' living spaces.