Site characterization and validation - Porous media modelling of validation tracer experiments.

摘要

A three dimensional porous media model of the SCV site was developed to predict the observed hydraulic head distribution in the SCV site as well as the measured flux to the D boreholes during the simulated drift experiment (SDE) and the flux to the Validation drift. The SCV flux model was calibrated to reproduce the observed distribution of flux in the D boreholes and the validation drift and was used as the basis for simulating the solute transport of the tracer experiments carried out in the SCV site. The SCV transport model was calibrated using the measured breakthrough curves for the saline tracer tests. The porous media numerical simulations of the validation tracer experiments were designed to predict the transport of conservative tracers through the rock mass from selected boreholes in the SCV site. This prediction consisted of computing the tracer breakthrough curves for the validation drift as well as predicting t(sub 5) and t(sub 50), time to reach 5% and 50% of the 'steady state' breakthrough, and C(sub ss)/C(sub o), the normalized steady state breakthrough concentrations for each experiment. The computed distribution of hydraulic heads and tracer concentrations indicates that there is a relatively strong horizontal as well as vertical gradient in the H zone. Tracer from the more distant boreholes appears to bypass the drift and only appears in the drift as a result of lateral dispersion. A preliminary comparison of the predicted tracer results with the measured results, based on the breakthrough curves and values of t(sub 5), shows that in general the predicted tracer arrival times at the drift were too early and the predicted steady state relative concentrations of tracer were lower than measured. (au). (Atomindex citation 23:078610)