Uncertainty and sensitivity analysis for two-phase flow in the vicinity of the repository in the 1996 performance assessment for the Waste Isolation Pilot Plant: disturbed conditions

Uncertainty and sensitivity analysis results obtained in the 1996 performance assessment (PA) for the Waste Isolation Pilot Plant (WIPP) are presented for two-phase flow in the vicinity of the repository under disturbed conditions resulting from drilling intrusions. Techniques based on Latin hypercube sampling, examination of scatterplots, stepwise regression analysis, partial correlation analysis and rank transformations are used to investigate brine inflow, gas generatio~ repository pressure, brine saturatio~ and brine and gas outflow. Of the vari~bles under study, repositoq pressure and brine flow fi-om the repository to the Culebra Dolomite are potentially the most important in PA for the WIPP. Subsequent to a drilling intrusio~ repository pressure was dominated by borehole permeability and generaIly below the level (i.e., 8 MPa) that could potentially produce spallings and direct brine releases. Brine flow from the repository to the Culebra Dolomite tended to be w-nail or nonexistent with its occurrence and size also dominated by borehole’permeability.