From model closure to continuity with nature: Reframing safety in deep geological disposal

What counts as safety in deep geological disposal—and what disappears when safety is defined in model terms? This paper re-examines repository safety assessment through canister interception by future drilling, a scenario used in safety cases. In current assessments, this scenario is resolved through short-term radiological exposure of selected receptors, without extending the analysis to environmental fate. Such assessments are internally consistent within a robustness-test logic: they ask whether a localised canister breach would compromise repository isolation. Yet once drilling brings waste material to the surface, that material has already crossed the safety boundary established by repository isolation. Very high doses may be acknowledged within the intrusion scenario, while the longer-term fate of surfaced material remains outside the recognised frame of consequence. Uranium—which dominates spent-fuel mass and persists as both a radiological and chemical hazard—makes this truncation materially visible by allowing the chemical and ecological consequences of surfaced repository material to be examined beyond the short-term radiological exposure frame. Combining a comparative review of Swedish and Finnish spent-fuel safety cases with an environmental illustration of uranium's behaviour after surface release, the paper interprets this truncation as model closure: the convergence of technical closure within the model and administrative closure within regulatory practice, through which open-ended environmental consequences are stabilised as a bounded safety object. It argues for reframing repository safety not only as containment, but as continuity with nature: the capacity to account for the persistence, mobility, and ecological interaction of released materials once they re-enter surface systems.