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

Abstract

It has been established that radionuclides accumulates during mining and mineral ore processing, leaching into water bodies and thus increases natu- rally occuring radioactive materials (NORM) concentration levels. In this work, theoretical and experimental methods have been used to study ra- dionuclides 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- di_usion equation in underground system. A mathematical model using a numerical solution based on the _nite di_erence 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-di_usion equations using available site speci_c parameters. The results of the model predict an increasing concentration of radionuclides of the U-Th Series and the potential radiation doses through consump- tion of groundwater in the study area. The solutions may prove useful for simpli_ed analysis of radionuclide transport in groundwater. Analyti- cal solution was used to verify the results from the numerical model with some experimental data obtained from gamma ray spectroscopy analysis. For experimental veri_cation two sampling zones were earmarked: within 5 kilometers radius and 10 kilometers radius from the mine concession. The average annual committed e_ective doses from theoretical and experimen- tal methods were 1.14 _Sv and 1.05 _Sv 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.