Crystalline Ceramics: Waste Forms for the Disposal of Weapons Plutonium

Nuclear waste forms for actinides

“…Present research on waste forms for Pu-immobilization includes a relatively short list of phases (Table 2). In the U.S., most of the effort within the Materials Disposition program of the Department of Energy focuses on immobilization in a ceramic (24), particularly cubic pyrochlore and its monoclinic derivative, zirconolite, because there are considerable data on these materials as waste form phases (22). However, the Department of Energy evaluation and selection process (24) is very different from the mineralogic approach presented in this paper.…”

“…This was a highly contentious period (18)(19)(20) when a wide variety of ''alternative'' waste forms competed with borosilicate glass as the ''reference'' waste form (21). Although vitrification was finally selected for the Savannah River HLW (the Defense Waste Processing Facility began vitrifying waste in 1996), work on alternative waste forms has continued to the present day and provides the present basis for the discussion of waste forms for weapons plutonium (22).…”

Molar heat capacity and thermodynamic functions of zirconolite CaZrTi2O7

“…In their present form, these materials could easily be utilized in weapons and pose a substantial national security risk. Chemical immobilization in a ceramic mineral form, (1)(2)(3)(4) or vitrification (4,5) of the plutonium and uranium reduces this risk to a level similar to that of spent nuclear fuel and makes plutonium recovery for weapons use difficult. The U.S. Department of Energy has identified ceramic minerals as the preferred form for plutonium disposition by immobilization.…”

The thermodynamics of formation, molar heat capacity, and thermodynamic functions ofZrTiO4(cr)

“…(1,2) Among the phases found in these ceramics is zirconolite (CaZrTi 2 O 7 ). (3)(4)(5) Important to the development, performance modeling, and optimization of a nuclear waste host is an understanding of the formation energetics of the phases that comprise the waste material.…”