Radiation dose due to radon and thoron progeny inhalation in high-level natural radiation areas of Kerala, India

In order to evaluate internal exposure to radon and thoron, concentrationsfor radon, thoron, and thoron progeny were measured for 259 dwellingslocated in high background radiation areas (HBRAs, outdoor external dose:3–5 mGy y−1) and low background radiation areas (control areas, outdoorexternal dose: 1 mGy y−1) in Karunagappally Taluk, Kerala, India. Themeasurements were conducted using passive-type radon-thoron detectors andthoron progeny detectors over two six-month measurement periods from June2010 to June 2011. The results showed no major differences in radon andthoron progeny concentrations between the HBRAs and the control areas. Thegeometric mean of the annual effective dose due to radon and thoron wascalculated as 0.10 and 0.44 mSv, respectively. The doses were small, but notnegligible compared with the external dose in the two areas

A pilot study for dose evaluation in high-level natural radiation areas of Yangjiang, China

A pilot study to measure ambient gamma dose rate and radon and thoron progeny concentrations was made for eight dwellings selected in Yangjiang, China. Indoor and outdoor ambient gamma dose rates were 110–370 and 100–220 nGy h-1, respectively. Doses received from indoor terrestrial radiation were estimated to be 0.6–1.8 mSv year-1. Radon, thoron and thoron progeny concentrations were 19–98, 18–1120 and 0.4–10.3 Bq m-3, respectively. This pilot study showed that the position of passive-type monitors to be placed and the deployment period should be carefully determined for estimating reliable annual average concentrations