走行サーベイによる四国の環境放射線調査

We investigated the environmental radiation in Shikoku area using a car-borne survey and obtained the change of dose rate by continuous survey. Dose rartes in Ozu city and its surrounding area, Ehime prefecture were the lowest in other areas of Shikoku. Dose rates obviously changed on the north side of it’s low dose rates area but gradually changed on the south side. Dose rates in Ashizuri-misaki, Kochi prefecture were the highest in Shikoku and changed in accordance with the boundary of geological structure. Dose rate on the survey route, from Imabari city in Ehime prefecture to Shimanto city in Kochi prefecture, was the lowest at the surrounding area of the prefectural boundary. This lowest dose rate was considered to be caused by geological structure. The influence of altitued on dose rates was not observed in this survey route.The average dose rates of environmental radiation in Ehime prefecture and Kochi prefecture were almost the same and the lowest in Shikoku. Tokushima prefecture was the highest in the average dose rates of environmental radiation of other prefectures in Shikoku.