Mapping of y -emitting radionuclides from Princess Mine Dump and the potential radiological effects on human beings

Abstract

The study was carried out at the Princess dump, an old abandoned mine tailing storage facility in the Witwatersrand region of South Africa. It was aimed at identifying the NORMS in the dump and their activity concentrations using a High Purity Germanium detector. According to literature the South African gold mines are associated with high levels of uranium. The mining activities in general tend to elevate the concentrations of NORMS near the earth surface. The main objectives were to identify the available NORMS from the tailing , measure their activity concentrations and using hazard indices and dose calculation to estimate the risk the mine dump poses to the communities around it. The radionuclides were identified and their average activity concentrations were 162.8 ± 32 Bq/kg, 24. 9 ± 1.3 Bq/kg, 214.5 ± 37 Bq/kg, and 97.4 ± 8.5 Bq/kg for 238U, 232Th, 226Ra, and 4°K, respectively. The activity concentrations were compared to the world average concentrations determined by UNSCEAR, 2008 of 33 Bq/kg, 35 Bq/kg, 45 Bq/kg and 412 Bq/kg for 238U, 226Ra, 232Th and 4°K, respectively. The average activity concentration of 226Ra was found to be the only one which is higher than the UNSCEAR values while the rest were only below. The average radium equivalent of 233 Bq/kg and the absorbed dose at 1 m above the dump of 94.6 nGy/h was determined. The hazard index of 0.68 was calculated from the data and was found to comply with the UNSCEAR limits, since it is below one. The results indicate that Princess Mine Dump does not pose any radiological hazard to the nearby community by its presence. The average activity concentrations are slightly lower than the world averages according to UNSCEAR values. It is recommended that the detailed dust transfer measurements be undertaken in the vicinity of the communities so as ensure that final recommendation can be drawn to assure the safety of the public living in the nearby communities.