Journal Article Estimation of External Dose by Car-Borne Survey in Kerala, India

Hosoda, M.  ,  Tokonami, S.  ,  Omori, Y.  ,  Sahoo, S.K.  ,  Akiba, S.  ,  Sorimachi, A.  ,  ishikawa, T.  ,  Nair, R.  ,  Jayalekshmi, P.A.  ,  Sebastin, P.  ,  Iwaoka, K.  ,  Akata, N.  ,  Kudo, H.

10 ( 4 )  , pp.e0124433-1 - e0124433-11 , 2015-04
A car-borne survey was carried out in Kerala, India to estimate external dose. Measure-ments were made with a 3-in × 3-in NaI(Tl) scintillation spectrometer from September 23 to 27, 2013. The routes were selected from 12 Panchayats in Karunagappally Taluk which were classified into high level, mid-level and low level high background radiation (HBR) areas. A heterogeneous distribution of air kerma rates was seen in the dose rate distribution map. The maximum air kerma rate, 2.1 μGy/h, was observed on a beach sand surface. 232Th activity concentration for the beach sand was higher than that for soil and grass sur-faces, and the range of activity concentration was estimated to be 0.7–2.3 kBq/kg. The con-tribution of 232Th to air kerma rate was over 70% at the measurement points with values larger than 0.34 μGy/h. The maximum value of the annual effective dose in Karunagappally Taluk was observed around coastal areas, and it was estimated to be 13 mSv/y. More than 30% of all the annual effective doses obtained in this survey exceeded 1 mSv/y.

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