Long-term measurements of residential radon, thoron, and thoron progeny concentrations around the Chhatrapur placer deposit, a high background radiation area in Odisha, India. (October 2016)

• Record Type: Journal Article
• Authors: Omori, Yasutaka; Prasad, Ganesh; Sorimachi, Atsuyuki; Sahoo, Sarata Kumar; Ishikawa, Tetsuo; Vidya Sagar, Devulapalli; Ramola, Rakesh Chand; Tokonami, Shinji
• Is Part Of: Journal of environmental radioactivity. Volume 162/163(2016:Oct.)
• Page Start: 371
• Page End: 378
• Publication Date: 2016-10
• Subjects: Ambient gamma dose rate -- External dose -- High background radiation area -- Internal dose -- Radon -- Thoron; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2016.06.009
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: The Chhatrapur placer deposit is found in a high background radiation area which has been recently identified on the southeastern coast of India. Previously, some geochemical studies of this area were carried out to assess external dose from radionuclides-bearing heavy mineral sands. In this study, radon, thoron and thoron progeny concentrations were measured in about 100 dwellings during three seasons (autumn-winter, summer, and rainy) in a 10- to 12-month period and annual doses due to inhalation of them were evaluated. The measurements were made by passive-type radon-thoron discriminative detectors and thoron progeny detectors in which solid state nuclear track detectors were deployed. The results show that radon and thoron concentrations differ by one order of magnitude depending on exposure periods, while thoron progeny concentration is nearly constant throughout the year. Since thorium-rich sand is distributed in the studied area, exposure to thoron is equal to, or exceeds, exposure to radon and is not negligible for dose evaluation. Based on the measurements, doses due to inhalation of radon and thoron are evaluated as 0.1–1.6 mSv y −1 and 0.2–3.8 mSv y −1, respectively. The total dose is 0.8–4.6 mSv y −1, which is the same order of magnitude as the worldwide value. Highlights: Radon, thoron and thoron progeny concentrations were measured in Odisha, India. Exposure to thoron is equal to, or exceeds, exposure to radon in internal dose. Internal dose from radon and thoron was comparable to external dose.