Abstract
Assessment of the long-term safety of geological disposal needs to be based on a clear understanding of uncertainty and the role of performance assessment is to support this undestanding. For this purpose, it is important to identify and evaluate uncertainties associated with understanding the geological environment, which often exhibits significant heterogeneity at various scales. This evaluation must be done at every stage of the site characterization so that insights, thus gained, can be used to guide designing effective measures to reduce the uncertainty. In many applications, however, only a limited number of most plausible model options and data-sets are sought after and this prevents one from recognizing uncertainty explicitly. In the current study we propose an alternative approach where all the possible options in the models and data-sets that cannot be excluded in the light of the evidence available is identified. This approach enables uncertainties associated with the understanding at a given stage of the site characterization to be made explicitly. This, in turn, supports the design of the following stage to reduce the uncertainties efficiently. In this paper a methodology for analyzing the uncertainty in a heterogeneous geological environment is discussed. The methodology has also been tested in Tono area, to demonstrate its applicability.
