[en] A dynamic theory, based on the reflectionless stress intensity factor concept, is used to analyse a very simple model. The theoretical results underscore the view that the current ASME Code procedure is unduly conservative when it is applied to predict crack arrest in a situation where the surface to which the crack propagates is able to bend. This conclusion is important with regard to the integrity of nuclear reactor pressure vessel when it is subjected to hypothetical pressurized thermal shock event. (author)