Application of hydrogeochemical data to groundwater flow and radionuclide transport modelling in the Canadian Nuclear Fuel Waste Management Program

Hydrogeochemical data have been obtained for groundwaters in the granitic Lac du Bonnet granitic Batholith for the last 15 years as part of the Canadian Nuclear Fuel Waste Management Program. These data have been used to: 1) characterize hydrogeochemical variations to depths of 1000 m in the Batholith and for the Underground Research Laboratory (URL) lease area; 2) provide information for the construction and calibration of structural, regional groundwater flow and performance assessment (PA) models of the geosphere for a hypothetical nuclear fuel waste disposal vault at a depth of 500 m near the URL; 3) test models of uranium solubility and migration; 4) provide specific information to understand unanticipated hydrogeologic characteristics observed at depth in sparsely fractured rock; and 5) confirm results of groundwater flow modelling. Examples were described of how site-specific hydrogeochemical data have been used in the construction, calibration and qualitative confirmation of groundwater flow models in the Whiteshell Research Area (WRA). Examples are also given of how hydrogeochemical information has contributed to models of the vault, geosphere and biosphere as part of performance assessment calculations. (author)