Critical event (CE) (in the bow-tie):

In Bow-tie Terminology: This term is commonly defined as the event causing a loss of containment (LOC). This definition is quite accurate for fluids, as they usually behave dangerously after release. For solids and more especially for mass solid storage, the term “loss of physical integrity” (LPI) is considered more appropriate, as the critical event in this case is the change of chemical and/or physical state of the substance. The critical event is the centre of the bow-tie.