Fracture network model of the groundwater flow in the Romuvaara site

摘要

In the study, computer codes are employed to analyze the groundwater flow patterns in the sparsely fractured intact rock at the Romuvaara site. The new fracture data gathered during the detailed site characterization phase demonstrated that the characteristic properties of fractures can be estimated quite reliably from few boreholes and outcrops. Results obtained by employing new methods, like the use of borehole-TV, changed the fracture intensity of the potential water conducting fractures compared to the earlier model. In the preliminary site investigation phase, only the orientated fractures were used to derive the parameters of the intact rock. In the present model, all the fractures outside the known fracture zones are used. The hydraulic conductivity tensor of the intact rock was estimated with the fracture network model. The flow simulations were calculated for a 16 cu m rock volume and about 2000 fractures. The flow rate distribution through the cross sectional area of the disposal canisters was calculated for a set of ten realizations and a large number of different canister positions. The total number of canister positions simulated was 2200. The flow distribution in larger volume was studied using a method that searched the flow routes of highest conductance. The flow routes were examined into north-south, east-west, and vertical directions. Flow routes along homogeneous and heterogeneous fractures were compared. (21 refs.). (Atomindex citation 28:049145)