PLoS ONE (Jan 2015)

Estimation of external dose by car-borne survey in Kerala, India.

  • Masahiro Hosoda,
  • Shinji Tokonami,
  • Yasutaka Omori,
  • Sarata Kumar Sahoo,
  • Suminori Akiba,
  • Atsuyuki Sorimachi,
  • Tetsuo Ishikawa,
  • Raghu Ram Nair,
  • Padmavathy Amma Jayalekshmi,
  • Paul Sebastian,
  • Kazuki Iwaoka,
  • Naofumi Akata,
  • Hiromi Kudo

DOI
https://doi.org/10.1371/journal.pone.0124433
Journal volume & issue
Vol. 10, no. 4
p. e0124433

Abstract

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A car-borne survey was carried out in Kerala, India to estimate external dose. Measurements 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 surfaces, and the range of activity concentration was estimated to be 0.7-2.3 kBq/kg. The contribution 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.