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

Uncertainty and sensitivity analysis results obtained in the 1996 performan ce assessment for the Waste Isolation Pilot Plant are presented for two-pha se how in the vicinity of the repository under undisturbed conditions. Tech niques based on Latin hypercube sampling, examination of scatterplots, step wise regression analysis, partial correlation analysis and rank transformat ions are used to investigate brine inflow, gas generation, repository press ure, brine saturation, and brine and gas outflow. Of the variables under st udy, repository pressure is potentially the most important due to its influ ence on spallings and direct brine releases, with the uncertainty in its va lue being dominated by the extent to which the microbial degradation of cel lulose takes place, the rate at which the corrosion of steel takes place, a nd the amount of brine that drains from the surrounding disturbed rock zone into the repository. Published by Elsevier Science Ltd.