222Rn Distribution Pattern in Dwellings of Copper Mineralized Area of East Singhbhum Region, Jharkhand, India

Abstract

Seasonal variation of 222 Rn levels was studied in the dwellings in U-Cu mineralized area of East Singhbhum, Jharkhand, India. Copper mining and processing industry is operational in this area for the last hundred years. Copper minerals of this region contain a significant fraction of uranium and the decay products. To measure the activity concentration of 222 Rn, LR-115, type-II solid-state nuclear plastic track detector was used in an indigenously developed radon dosimeter cup. A higher value of 222 Rn activity concentration was recorded in some of the dwellings in the mineralized zone. The results at different locations adjoining the facilities show that the 222 Rn activity concentration varies to a great extent following an approximate log-normal distribution. The observed range varied from 29.1 and 314.6 Bq m -3 with an overall geometric mean of 72.3 Bq m -3 and geometric standard deviation 1.67. Further, in poorly ventilated dwellings 222 Rn levels were higher compared to the properly ventilated houses. The peak activity concentration of 222 Rn was recorded during winter (December-February). Appreciably lower activity concentration of radon was observed during summer and rainy seasons. The results reflect that the levels are higher than the global average indoor activity concentration of 40 Bq m -3 (UNSCEAR-1993) for 222 Rn, but are comparable to the studies carried out in similar types of geological formations.