Abstract:
Radionuclides transport and dose assessment to the public in a groundwater system are
described using theoretical and experimental methods. It is known that radionuclides could
accumulate during mining and mineral ore processing and reach into water bodies, and thus
contribute to the radiation dose received by the public who consume this water. As
groundwater is inaccessible, a mathematical model with a numerical method is used to
describe the relevant physical processes during radionuclide transport in the groundwater
system. A computer programme has been written in MatLab to implement the numerical
solution. The activity concentration and annual committed effective dose to the public from
natural radionuclides (NORM) are determined for both theoretical and experimental
methods. The NORM elements of interest are 238U, 232Th and 40K. The results obtained
from the study revealed that the concentration of NORM in Taparko groundwater system
increases with time at the point of release and becomes constant at a certain time. The
concentration then decreases rapidly as far as from the release point. The average activity
concentrations for theoretical method were 0.3 Bq/L, and 0.05 Bq/L for 238U and 232Th
respectively at 600 m from the discharged point where the water from boreholes and wells
is used by the public. For experimental analysis the mean activity concentrations were 5.57
Bq/L, 0.58Bq/L and 4.78 Bq/L for 238U, 232Th and 40K respectively. The corresponding
average annual committed effective doses estimated were 0.13mSv/y, 0.28 mSv/y, for
theoretical and experimental methods respectively. The theoretical and experimental
results indicate insignificant exposure of the public to Natural Occurring Radioactive
Materials (NORM) from the activities of the Goldmine.