Origin and subsurface migration of radionuclides from waste rock at an abandoned uranium mine near Bancroft, Ontario

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Authors:Veska, Eric
Source:386p. Institution: University of Waterloo, Waterloo, ON, Canada
Publication Date:1983
Note:In English. Doctoral dissertation
Summary:An area of old waste rock on a sand aquifer at the abandoned Greyhawk uranium mine near Bancroft, Ontario, was monitored. The waste rock has been abandoned for more than two decades. The groundwater velocities in the aquifer were found to decrease progressively from a maximum at 70 m/yr below the waste rock to about 2 m/yr at approximately 125 m downgradient from the waste rock. Waste-rock-derived contaminant plumes of sulfate, bicarbonate, dissolved inorganic carbon, 238U, 226Ra and 210Pb were identified in the aquifer. The lateral extent of 238U and 234U contamination downgradient from the waste rock is less than 80 meters, whereas the lateral extent of 226Ra, 210Pb, 230Th and 232Th contamination is less than 20 meters. The observed frontal positions of 238U, 226Ra, 210Pb and 230Th contamination in the sand aquifer were simulated using the advection-retardation model with uniform groundwater velocity and chemistry and the cell model with non-uniform groundwater velocity and chemistry. The results from both models indicated good agreement between the analytical and simulated frontal positions of 226R, 210Pb and 230Th in the aquifer. For the case of the uranium isotopes, the simulated results from the transport models only partly corresponded with that of the analytical results. The transport models were also used to predict the future spread of radionuclide contamination in the aquifer. The analytical 234U activity in groundwater was found to increase progressively with respect to the analytical 238U activity downflow from the waste rock. An explanation was given for this phenomenon based on the different percentages of the (IV) and (VI) oxidation states of the 234U and 238U atoms in the contaminated groundwater. Modified author abstract.
Subjects:Actinides; Alkaline earth metals; Aquifers; Engineering geology; Environmental geology; Geochemistry; Ground water; Isotopes; Metal ores; Metals; Migration; Oxidation; Pollution; Ra-226; Radioactive isotopes; Radioactive waste; Radium; Simulation; Surveys; Tailings; Th-230; Th-232; Thorium; U-234; U-238; Uranium; Uranium ores; Velocity; Waste disposal; Bancroft Ontario; Canada; Eastern Canada; Hastings County Ontario; Ontario; Ratios; Rb-210; Southern Ontario; Trans-uranium elements
Coordinates:N450000 N450000 W0770000 W0770000
Record ID:1984040821
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute.
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