Environmental Rn levels around an Indian U complex

The ambient Rn behaviour in the environment around an Indian U complex at Jaduguda is investigated using grab sampling as well as time-integrated monitoring techniques in 1990–1996. In this region with tropical-like climatic conditions, atmospheric Rn levels (i) range from 4.0 to 157 Bq m−3 with a standard geometric mean of 22 Bq m−3, (ii) attain minima in the afternoon and about 1.5–5 times greater in the morning before sunrise, (iii) exhibit a minimum level during the rainy season and about 4 times greater in winter as a maximum, (iv) average at lower concentrations in days with cloudy skies compared to clear skies. There is a negative linear correlation coefficient of −0.92 between monthly mean ambient temperature and Rn concentration. The radiological significance of Rn levels in air in the nearby areas and the natural background is discussed.