Natural analogues and performance assessment

Abstract

At a high general level this paper presents a number of data types needed for performance assessment (PA) of the potential high level nuclear waste repository at Yucca Mountain, NV. These include hydrology (e.g. fluxes through a breached waste package and to the accessible environment), geochemistry (e.g. water composition and changes thereto due to corrosion and waste dissolution; radionuclide solubilities), the engineered barrier system (e.g. rates and times of container failure; degradation of concrete), the source term, and disruptive scenarios. Some characteristics of three natural analogues, specifically the Taupo Volcanic Zone (New Zealand), Pena Blanca (Mexico), and Cigar Lake (Canada) are then compared against these needs. Each of these sites possesses the potential to provide insights about the long term behavior of the natural system in relation to a few of these characteristics and data needs. The characteristics that pertain to performance at Yucca Mountain differ from site to site and largely do not overlap each other. The paper presents one way of evaluating the potential applicability of studies at a specific site to PA. The way in which such studies would be used by PA is not discussed.