Plutonium partitioning and speciation was studied under the conditions of a liquid nuclear waste repository site. The dominating effect of corrosion products (Fe and Cr) oxides on plutonium partitioning was established in batch sorption tests at 150 ℃ and by using sequential extraction. Various techniques including Mössbauer spectrometry, XRD and TEM were used to characterize Fe/Cr oxide phases that form both precipitates and surface coatings which sorb plutonium. The sorption and speciation of plutonium was modeled thermodynamically using Pourbaix diagram that takes into account both surface complexation reaction and precipitation of insoluble PuO2.
The study was supported by the Russian Foundation for Basic Research (projects 14-03-00821, 14-03-92703). We also acknowledge the “Nanochemistry and nanomaterials” user facility of the Department of Chemistry of MSU and A. V. Egorov for providing the TEM measurements. Authors thank A. V. Sobolev, D. A. Pankratov for providing Mössbauer spectra measurements.
©2014 Walter de Gruyter Berlin/Boston