Multivariate regression analysis to assess the 222Rn exhalation rates from uranium ores and their relative contributions to the 222Rn concentration in the underground uranium mine atmosphere

Abstract

Multivariate regression models involving radium (226Ra) content and porosity to fit surface and mass radon (222Rn) exhalation rates from uranium ores were established in this paper. This paper also presents the contributions of the orebody and broken ore piles to the 222Rn concentration in an Indian underground uranium mine. Statistical regression models explained 94% of the variation of the radon exhalation rates. Based on a statistical analysis of data, the porosity was considered as one of the significant parameters influencing the 222Rn exhalation rates from uranium ores. This study revealed that the surface 222Rn exhalation varied from 0.0112 to 0.735 Bq/s per m2 with the geometric mean of 0.0884 Bq/s per m2. The mass 222Rn exhalation rate varied from 0.92 to 46.94 Bq/h per kg with the geometric mean of 6.58 Bq/h per kg. The total contributions of the orebody and broken ore piles to 222Rn concentrations were about 6% of the lower workplace reference level stipulated by the regulatory body. It revealed that the orebody and broken ores were not prominent for the radon concentration level under the existing mine ventilation system.