Caturing uncertainty in unsaturated-zone flow using different conceptual models of fracture-matrix interaction

摘要

A key part of Performance Assessment (PA) calculations is the examination fo the effects of dat uncertainty on performance measures.In the evaluation of Yucca Mountain as a potential nuclear waste repository,the unsaturated zone (UZ) is a critical portion of the natural barrier for mitigating radionuclide migration.There are many parameters needed to model unsaturated zone flow for which there is much uncertainty.Many past PA calculations have accounted for the uncertainty in parameters by randomly sampling from parameter.Many past PA calculations have accounted for the uncertainty in parameters by randomly sampling from parameter distributions and using sampled parameters in flow models~1,2. One of the problems with this approach is the possibility of getting a combination of parameter values that does not reproduce what is known about the system (e.g.,measured matrix saturations) when used in a flow model.