Materials Interactions and Temperatures in the Three Mile Island Unit 2 Core

AbstractCore debris samples obtained from different regions of the Three Mile Island Unit 2 (TMI-2) core were examined to characterize the interaction among core components and the coolant, to determine the peak temperatures at which the interactions occurred, and to evaluate core melt progression in TMI-2. Estimates of peak temperatures were needed from these samples because of the strong influence that temperature has on core damage progression and fission product behavior. The peak temperatures can be bounded by comparing the observed microstructure and compositions with established phase diagrams. The microstructures were determined by optical metallography and scanning electron microscopy, and compositions were determined by energy and wavelength dispersive X-ray spectroscopy and scanning Auger spectroscopy.The material interactions among the core components are very complex and involve not only the interaction between the Zircaloy cladding and the UO2 fuel, but interactions with control rod material...