The Influence of Future Human Behaviors in Performance Assessment -10483

ABSTRACT Future human exposure to materials disposed in radioactive waste repositories is potentially a low-probability / high-consequence event. Probabilistic methods are often used in performance assessments (PAs) with respect to containment of wastes and their migration in the environment, but are not commonly applied to the exposure models that describe the behavior of potentially exposed individuals and groups of people. A probabilistic framework for assessing and presenting the potential for future exposures, and associated radiation doses, is presented. The framework differentiates dose results that are conditional on exposure (consequence analysis) and dose results that account for the likelihood of exposure. Under site conditions associated with a low probability of future exposure, such as when a repository is in a remote area and/or protected by intrusion barriers, simulations of individual or population dose may show that the expected dose is essentially zero within the performance period, but with a small chance of significant doses. The implications of such conditions for measuring disposal system performance and for risk management are discussed