INTRAVAL phase 2, test case 8, Alligator Rivers Natural Analogue - Modelling of uranium transport in the weathered zone at Koongarra (Australia). Final report
Cast your vote
You can rate an item by clicking the amount of stars they wish to award to this item.
When enough users have cast their vote on this item, the average rating will also be shown.
Your vote was cast
Thank you for your feedback
Thank you for your feedback
MetadataShow full item record
TitleINTRAVAL phase 2, test case 8, Alligator Rivers Natural Analogue - Modelling of uranium transport in the weathered zone at Koongarra (Australia). Final report
Translated Title[INTRAVAL fase 2, test case 8, Alligator Rivers Natuurlijk Analogon - Modellering van uraniumtransport in de verweerde zone in Koongarra (Australie). Eind rapport.]
PubliekssamenvattingAbstract niet beschikbaar
A study of uranium transport in one of the best studied "natural analogue sites", the Koongarra site of Alligator Rivers uranium deposit (Australia), is carried out. The purpose of this research is to test the simulation package METROPOL, developed at RIVM to simulate transport of radionuclide, over large time scales. At the Koongarra site secondary uranium mineralization and dispersed uranium, is present from the surface down to the base of weathering, some 25 meters deep. In the Koongarra uranium deposit, the transport processes have been going on for a few (1-3) million years, and during this period many climatological, hydrological and geological changes have taken place. Field data show that three layers can be distinguished in the Koongarra area: i) a top layer which is fully weathered, ii) an intermediate layer which is partially weathered (the transition zone) and iii) a lower layer which is unweathered. The groundwater velocities are largest in the transition zone which has been moving downward as the weathering process proceeds. The transport of uranium in the transition zone is simulated with the finite element code METROPOL. It has been adapted to account for the movement of the transition zone and to describe the dissolution of uranium in the orebody by a non-equilibrium relation. In the simulations a qualitatively reasonable agreement between calculated and measured soluble uranium concentration in the present transition zone is achieved. In this study was shown that over large timescales geologic processes may have a large impact on the transport of radionuclides ; over large timescales, the movement of the transition zone will have a large impact on the uranium concentration distribution. The simulation results in this study are stongly influenced by the parameters values, which are difficult to estimate for a period of some million years. The largest uncertainties are associated with the boundary conditions.