Deviations in performance that are judged to be hypothetical, at least in the one-million-year time period for assessment, may nonetheless be propagated to the analysis of radiological consequences as hypothetical “what-if?” cases, designed to demonstrate the robustness of the repository system. On the one hand, “what-if?” cases can be related to real physical phenomena; such cases are described in Section 7.4.1. On the other hand, Section 7.4.2 presents additional “what-if?” cases that postulate a degraded performance of each of the pillars of safety, unrelated to any physical phenomena.