Rapid expansion of Zircaloy cladding has been shown to occur at the relatively high temperatures predicted in the unlikely event of a loss-of-coolant accident. Of primary concern to reactor safety considerations is the subsequent effect upon the ability of the emergency core cooling system (ECCS) to arrest the thermal transient. Scoping calculations, using a multiple-channel, thermalhydraulic computer code, aimed at estimating the potential cooling effects are described. The deformations were calculationally represented as local conditions based on the subchannel area reductions. The analytical characterization of the flow blockage is the major uncertainty in the calculations. It is concluded that localized coolant subchannel reductions up to nearly 90% should not have significant deleterious effects on emergency core cooling performance.