Profiling hot isostatically pressed canister–wasteform interaction for Pu-bearing zirconolite-rich wasteforms
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Date
2022-04-02
Journal Title
Journal ISSN
Volume Title
Publisher
John Wiley & Sons, Inc
Abstract
Zirconolite-rich full ceramic wasteforms designed to immobilize Pu-bearing wastes were produced via hot isostatic pressing (HIP) using stainless steel (SS) and nickel (Ni) HIP canisters. A detailed profiling of the elemental compositions of the major and minor phases over the canister–wasteform interaction zone was performed using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS) characterization. Bulk sample analyses from regions near the center of the HIP canister were also conducted for both samples using X-ray diffraction and SEM-EDS. The sample with the Ni HIP canister showed almost no interaction zone with only minor diffusion of Ni from the inner wall of the canister into the near-surface region of the wasteform. The sample with the SS HIP canister showed ∼100–120 μm of interaction zone dominated by high-temperature Cr diffusion from canister materials to the wasteform with the Cr predominantly incorporated into the durable zirconolite phase. We also examined, for the first time, changes to the HIP canister wall thickness caused by HIPing and demonstrated that no canister wall thinning occurred. Instead, in the areas examined, the canister wall thickness was observed to increase (up to ∼20%) due to the compression occurring during the HIP cycle. Further, only sparse formation of (Cr, Mn)-rich oxide particles were noted within the HIP canister inner wall area immediately adjacent to the ceramic material, with no evidence for reverse diffusion of ceramic materials. Though the HIP canister–wasteform interaction extends to ∼120 μm when using an SS HIP canister for the system investigated, this translates to <<1 vol.% for an industrial scale HIPed wasteform. Importantly, the HIP canister–wasteform interactions did not produce any obviously less durable phases in the wasteform or had any detrimental impact on the HIP canister properties. © 2022 Commonwealth of Australia. Journal of the American Ceramic Society published by Wiley Periodicals LLC on behalf of American Ceramic Society.
Description
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License. Open access publishing facilitated by Australian Nuclear Science and Technology Organisation, as part of the Wiley - Australian Nuclear Science and Technology Organisation agreement via the Council of Australian University Librarians.
Keywords
Hot pressing, Containers, Waste forms, Zirconolite, Radioactive wastes, Synthetic rocks, Plutonium
Citation
Dayal, P., Farzana, R., Zhang, Y., Lumpkin, G. R., Holmes, R., Triani, G., & Gregg, D. J. (2022). Profiling hot isostatically pressed canister–wasteform interaction for Pu‐bearing zirconolite‐rich wasteforms. Journal of the American Ceramic Society, 105(8), 5359-5372. doi:10.1111/jace.18458