Laboratory examination of debris recovered from the upper tubesheet of the Three Mile Island Unit 2 Bloop steam generator was performed as part of a series of technical evaluations of postaccident core damage. The analysis of a sample of loose, gravel-like debris is of special interest since it is believed to have been transported from the core region during the core damage sequence between 174 and 192 min to the upper tubesheet when reactor coolant pump B was restarted. The characterization of five size fractions and ten of the largest particles was accomplished by destructive (chemical, radiochemical, metallography, and scanning electron microscopy/energy dispersive spectrometry) and nondestructive (photographic examination and density) methods of analysis. The results of this examination provided direct information on the extent of core damage when restart occurred.