Speaker
Description
The present work aimed at establishing the extent and distribution of the activity concentration levels of 238U daughter-nuclides; 226Ra and 222Rn in the
West Rand-area of Johannesburg. The main motive was to ascertain whether
the exposure of the nearby residents to ionising radiation due to former mining
activities was within the maximum acceptable limit of 1.0 mSv/y for the public. Measurements include the use of Alpha Spectroscopy system (Canberra)
with Passivated Implanted Planar Silicon (PIPS) and Solid-state Alpha Detectors for Radon measurements (RAD-7) detectors to identify radionuclides,
quantify and analyze isotopes of interest.
A seasonal collection of a total 32 water samples from the mining areas
was carried out and analysed for 226Ra and 222Rn. The results of radium
(
226Ra) concentration in water samples obtained by using alpha spectrometry
ranged from (1.58±2.74 to 164.42±18.47) mBq/l, (11.23±3.89 to 136.01±15.4)
mBq/l, (-3.38±-2.39 to 156.15±18.14) mBq/l, and (4.25±1.23 to 108±8) for
June 2019, September 2019, December 2019 and March 2020 water samples,
respectively. The radium values were lower than the suggested maximum contamination levels by US-EPA 555 mBq/L.
The results shows that the range of radon (222Rn) concentration values
vary from (37.1±74.1 to 269±79.2) mBq/l, (57.2±73.9to 190±94.9) mBq/l,
(76.6±63.2 to 211±146) mBq/l, and (56.3±71.1 to 289±272) mBq/l for June
2019, September 2019, December 2019 and March 2020, respectively. The obtained 222Rn concentration results in drinking water samples in the current
study are low than the approved maximum contamination level (MCL) 11.1
Bq/l as approved by US-EPA.
The observed radon annual ingestion dose from the current study were
lower than the European Commission and the World Health Organization proiii
posed concentration of 222Rn in drinking water of 100 Bq/l [1]. The results of
this study indicates that the total annual effective doses from possible intake
of 226Ra and 222Rn radionuclides in sampled water in West-Rand area were
found below the World Health Organisation (WHO) recommended limit of 0.1
mSv/y as well as the average radiation dose of 0.29 mSv/y received per head
worldwide due to ingestion of natural radionuclides assessed by UNSCEAR 2002
