Chemistry/electrochemistry of Spent Nuclear Fuel as a Wasteform

 Mineralogical Association of Canada Short Course 43, Winnipeg MB, May 2013, p. xx-xx INTRODUCTION The direct disposal of spent nuclear fuel in geologic repositories, built several hundred metres underground, has been under consideration internationally for 20 to 30 years. Various geologic formations are being, or have been, studied including tuff rock, salt domes, sedimentary clay deposits and granitic rock. The spent nuclear fuel would be encapsulated and sealed within a metallic container, most likely carbon steel possibly with an outer Cu shell and emplaced in bore holes or deposition tunnels within the repository. The space between the container and the borehole/tunnel wall would then be backfilled with sealing materials such as clays and clay/sand mixtures. A schematic illustrating the Canadian concept for disposal in crystalline rock is shown in Figure 11-1. This arrangement constitutes a multiple barrier system, Figure 11-2, including the engineered barriers (1, 2, and 3), a geotechnical barrier (4) and the geologic barrier (5). Other national concepts are based on the same multiple barrier concept, but the specific barrier designs may vary (Bennett & Gens 2008).