[en] This assessment seeks (1) to determine the most probable chemical compounds formed between fission products and actinides in urania fuels under normal and accident conditions and (2) to identify gaps in knowledge of these fission-product compounds. The ultimate goal of this effort is to develop predictive capability about the behavior of fission products under normal and acident conditions. The relevant thermochemical data have been organized by compound type, the chemical stability of resultant compounds determined, and data uncertainty evaluated. The assessment focused on fission-product and actinide oxides, halides, tellurides, and hydroxides. Free energy equations are given for those compounds for which data were available