Expert judgment elicitation: Application to science issues in siting facilities for geological disposal of nuclear waste

Abstract Two project case histories for geological disposal of nuclear waste are discussed in this and a companion contribution ( Chapter 21 ) with emphasis on the application of formalized treatments of scientific uncertainties in siting considerations. In this chapter, a decision support approach is described, governed by a formalized basis for eliciting and aggregating expert judgments in a rational and auditable way when reasoning under scientific uncertainties. The Classical Model for structured expert judgment elicitation is the theme common to both case histories, serving as a means for determining inputs to a logic tree assessment of the potential evolution of multiple tectonic hazards over extended future periods in the present case history, and providing a way for characterizing potential impacts of climate change on repository performance in the second case history. This chapter first notes the emerging role of structured expert judgment in radioactive waste management and geological disposal facility siting decisions, and describes the properties and attributes of the elicitation method adopted for both case histories. The first, discussed here, is a contribution to a major geological disposal facility siting program in Japan, where expert judgments were elicited in a pioneering approach for parameterizing a logic tree assessment of site-specific impacts due to hazards arising from different long-term tectonic evolution scenarios. Some generic insights on expert elicitation are summarized in the context of facility siting considerations, and suggestions made for further applications, research and methodology developments.