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 1m 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.