VITRIFICATION OF PLUTONIUM: CRITICALLY AND SAFEGUARDS CONSIDERATIONS

Criticality is a non-issue in the case of a high level waste glasspmducedtim reprocessing operations. However, criticality controlis a prerequisite for all stages of the vitrification option for weapons plutonium disposal, from the glass formulation and x~ Proces$ to the &Ome@ of the canister storage and the ultimate geologic disposal. All unit operations in the vitrification plant must employ critically safe equipment, either by geometry, mass,additionof neutron poisons, or by a combination of all three methods. In additiorL advanced safeguards techniques and materials control and accountability methods for verification and cdnnation memmme@ throughout the immobilization process can be expected to be applied. Mm@ the technicalcommunityis confident that the nuclear criticality safety aspects of evcny stage of weapons plutonium handling and processing can be addressed for all pre-disposal operations, the length of time a repositmy must remain criticality free is both a safkty and a regulatory issue. To date, there are no regulatory practices, DOE orders, or a general agreement on this question.