Radon exhalation rate in Chhatrapur beach sand samples of high background radiation area and estimation of its radiological implications

Chhatrapur beach placer deposit, situated in a part of the eastern coast of Orissa, is a newly discovered high natural background radiation area (HBRA) in India. The sand samples containing heavy minerals, were collected from Chhatrapur region by the grab sampling method at an interval of ∼ 1 Km. Radon exhalation rates were measured by sealed can technique using LR-115 type type II in the sand samples containing heavy minerals collected from the beach. Radon activity is found to vary from 1177.1 to 4551.4 Bq m-3 whereas the radon exhalation rate varies from 423.2 to 1636.3 mBq m-2h-1 with an average value of 763.9 mBq m-2 h-1. Effective dose equivalent in sand samples estimated from exhalation rate varies from 49.9 to 193.0 μSv y-1 with an average value of 90.1 μSv y-1. From the activity concentration of 238U, 232Th and 40K computed radium equivalent is found to vary from 864 .0 to 11471.5 Bq kg-1 with an average value of 3729.0 Bq kg-1. External hazard index, Hex range from 2.3 to 31.0 with a mean value of 10.1, which is quite high. This value supports the conclusion based on high mean absorbed gamma dose rate in air due to the naturally occurring radionuclides as 1627.5 nGy h-1. A positive correlation has been found between U concentration and radon exhalation rate in the sand samples. The use of sand as construction material may pose a radiation risk to ambient environment. (author)