Glaciation-induced radionuclide release: Implications for geological disposal of nuclear waste

Abstract Deep geological disposal of used nuclear fuel requires knowledge of how radionuclides behave over ~100 k.y. to 1 m.y. timeframes. New data from the Kiggavik uranium deposits, a natural analogue for deep geological disposal of nuclear waste, shows that oxidized subglacial waters may be injected deeply into the subsurface along fracture systems, resulting in limited radionuclide mobilization. Periods of radionuclide mobility correspond to episodes of climate change during glacial periods and occurred over ca. 36–471 ka time scales comparable to the evolution of Homo sapiens. While oxidized subglacial waters may pose a hazard to geologic disposal, resulting uranium transport is millions of times slower than glacial movements and short-range (<~5 cm). Reduction by preexisting uranium minerals and titanium oxides and adsorption onto clay minerals have effectively trapped radionuclides.