Modelling Radionuclides Transport and Fate in Groundwater Systems: A Case Study of Newmont Akyem Goldmine in Ghana

Abstract

It has been established that radionuclides accumulate during mining and mineral ore processing, leaching into water bodies and thus increases naturally occurring radioactive materials (NORM) concentration levels. In this work, theoretical and experimental methods have been used to study radionuclides transport and fate in groundwater systems at the Newmont Akyem Goldmine in the Eastern Region of Ghana. Radiation doses from radionuclides in groundwater have been modeled by considering advection diffusion equation in underground system. A mathematical model using a numerical solution based on the finite difference method has been used to describe the transport processes of radionuclides in the groundwater systems under continuous distraction as a result of mining activities.

A code written in Matlab was used to compute the numerical solutions of the advection-diffusion equations using available site specific parameters. The results of the model predict an increasing concentration of radionuclides of the U-Th Series and the potential radiation doses through consumption of groundwater in the study area. The solutions may prove useful for simplified analysis of radionuclide transport in groundwater. Analytical solution was used to verify the results from the numerical model with some experimental data obtained from gamma ray spectroscopy analysis. For experimental verification two sampling zones were earmarked: within 5 kilometers radius and 10 kilometers radius from the mine concession. The 1 Abstract 2 average annual committed effective doses from theoretical and experimental methods were 1.14 µSv and 1.05 µSv respectively. The trend of results of measurement from the gamma spectrometry analysis agreed with the model objective especially wells and boreholes that take their sources from the mine area.