Fissile material disposition program final immobilization form assessment and recommendation

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.…”

Diffuse reflectance and X-ray photoelectron spectroscopy of uranium in ZrO2 and Y2Ti2O7

“…Candidate ceramics for immobilisation considered here are monoclinic and stabilised zirconia [1][2][3] and pyrochlore-structured titanates [4,5], and we are studying the possible formation of high actinide valence states in these materials with an ultimate aim of understanding how to suppress these higher valence states which can form actinyl ions and tend to enhance leaching. In these materials, the actinide would be expected on the basis of ionic size to substitute for Zr in zirconia or Y in Y 2 Ti 2 O 7 .…”

Radiation damage effects in candidate titanates for Pu disposition: Pyrochlore

“…As a result of the review, the immobilization option was dropped [3]. In the meantime, the development of a concept for the immobilization of some weapons-grade Pu was ongoing [4][5][6][7]. In this program, a titanate ceramic containing approximately 10 mass% Pu was developed [7].…”