Multicycle Reprocessing and Refabrication Experiments on Sintered UO2 -Fissia Pellets

A multicycle reprocessing and refabrication scheme was simulated (using UO/sub 2/ spiked'' with fissia) to evaluate the feasibility of refabricating high-burnup UO/sub 2/ to a cumulative level of 10/sup 5/ Mwd/MTU. Various powder characteristics were studied, using oxidation-reduction methods as the reprocessing scheme. Processing conditions were established for the multicycle tests. Fissia, typical fission products (mostly oxides), were added to the reprocessed powder prior to compacting operations. There should be no difficulty in refabricating pellets from high-burnup material; conversely, the sinterability of UO/sub 2/ containing comparatively iarge concentrations of fissia is even enhanced. Well-formed pellets of density near 98% of theoretical were made for simulated burnups of 60,000, 80,000, and 100,000 Mwd/MTU. Cesium was the only fission element removed during processing.