Current status of waste package designs for the Yucca Mountain Project

Conceptual designs for waste packages containing spent fuel or high-level waste glass have been developed for use in a repository at Yucca Mountain. The basis for these designs reflects the unique nature of the expected service environment associated with disposal in welded tuff in the unsaturated zone. In addition to a set of reference designs, alternative design concepts are being considered that would contain and isolate the waste radionuclides in a more aggressive service environment. Consideration is also being given to the feasibility of a concept known as ``heat tailoring`` that employs the thermal energy released by the wasteforms to enhance and extend the performance of the containers. 5 refs., 3 figs.