The management and disposal of radioactive wastes are key international issues requiring a sound, fundamental scientific basis to insure public and environmental protection. Large quantities of existing nuclear waste must be treated to encapsulate the radioactivity in a form suitable for disposal. The treatment of this waste, due to its extreme diversity, presents tremendous engineering and scientific challenges. Geologic isolation of transuranic waste is the approach currently proposed by all nuclear countries for its final disposal. To be successful in this endeavor, it is necessary to...