X-Ray Absorption Fine Structure of Aged, Pu-Doped Glass and Ceramic Waste Forms

Abstract

ABSTRACTX-Ray Absorption Fine Structure (XAFS) spectroscopic studies were performed on a suite of compositionally identical Pu-doped simulated waste glasses prepared 15 years ago at different aactivities by varying the239Pu/f238Pu isotopic ratio. The resulting α-activities range from 1.9 × 107to 4.2 × 109 Bq/g. These samples have a current, accumulated dose that ranges from 8.8 × 1018to 1.9 × 1018αdecays/g. A second suite of polycrystalline zircon samples that were synthesized 16 years ago with 10.0 wt.% Pu was also investigated. The239Pu238Pu isotopic ratio in these samples resulted in α-activities of 2.5 × 108and 5.6 × 1010Bq/g and an accumulated dose of 1.2 × 1017and 2.8 × 1019α-decays/g. The multicomponent composition of the simulated waste glass permitted XAFS investigation at six elemental absorption edges. For both the glass and ceramic waste forms, initial analysis of Extended X-Ray Absorption Fine Structure (EXAFS) and X-Ray Absorption Near Edge Structure (XANES) indicate that the local environment around the cations exhibit different degrees of disorder as a result of the accumulated a-decay dose. In general cations with short cationoxygen bonds show little effect from self-radiation where as cations with long cation-oxygen bonds show a greater degree of disorder with accumulated a-decay dose.