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Xiaobin Xia, Kazuki Iijima, Gento Kamei, M. Shibata

Comparative study of cesium sorption on crushed and intact sedimentary rock

Keywords: Cesium sorption, Sedimentary rock, Dynamic circulation, Batch, Intact

For establishing a reliable safety assessment methodology for high-level radioactive waste (HLW) geological disposal, it is essential to clarify the applicability of sorption data determined with a conventional batch sorption method to an actual repository environment. In the present study, sorption data represented as distribution coefficients (K_d) were compared experimentally by applying a batch method with crushed sedimentary rock samples and a dynamic circulation method with intact sedimentary rock samples. The K_d values for cesium (Cs) determined with the dynamic circulation method are around one order of magnitude lower than those obtained using the batch method, depending on Cs concentration at sorption equilibrium. This disagreement was discussed considering permeability, specific surface area, solid/liquid ratio (S/L) and solution chemistry. The K_d values determined with the dynamic circulation method were corrected for different specific surface areas. As a consequence, the K_d values determined with the two methods are then comparable within an order of magnitude. The K_d values become even more comparable when taking into account that they decrease with increasing the S/L ratio as it is the case when going from batch to column experiments. The results basically suggest that the K_d determined with the batch method are reasonably applicable to describe sorption in the actual environment in a given nuclear waste repository after appropriate corrections.

Radiochimica Acta, Oldenbourg Wissenschaftsverlag

Print ISSN: 0033-8230
Volume: 94, 09/2006
Pages: 683 - 687

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