Following the proposals for nuclear fuel assurance of International Atomic Energy
Agency (IAEA) Director General Mohamed ElBaradei, former Russian President Vladimir V.
Putin, and U.S. President George W. Bush, joint committees of the Russian Academy of
Sciences (RAS) and the U.S. National Academies (NAS) were formed to address these and other
fuel assurance concepts and their links to nonproliferation goals. The joint committees also
addressed many technology issues relating to the fuel assurance concepts. This report provides

This report presents the analyses and results for the potential occurrence of external criticality events which could result from plutonium waste forms emplaced in a geologic repository similar to the one being developed at Yucca Mountain. The analyses evaluate both the MOX spent fuel and the immobilized plutonium waste forms in a repository if the waste package has degraded and if the fissile material has migrated to the invert and out into the far-field.