SENSITIVITY AND UNCERTAINTY ANALYSES APPLIED TO ONE-DIMENSIONAL RADIONUCLIDE TRANSPORT IN A LAYERED FRACTURED ROCK .2. PROBABILISTIC METHODS BASED ON THE LIMIT-STATE APPROACH

An uncertainty and probabilistic sensitivity study of a hypothetical u nderground high-level waste (HLW) repository intersected by a vertical fracture or fault and under saturated conditions is presented. Severa l recently developed probabilistic methods, including the advanced mea n value method and the adaptive importance sampling method, are applie d to a previously developed one-dimensional analytical model. These pr obabilistic methods are based on a limit-state formulation and provide an effective means of computing performance probability distribution and probability-based random parameter sensitivities. A numerical exam ple related to the transport of Np-237 in a system of layered fracture d rock is used to illustrate the application of these probabilistic me thods for efficient uncertainty and probabilistic sensitivity analyses .