Moderation of uncertainty in a database of sorption coefficients, 2; Analysis of data scatter by adopting ion exchange model

Oe, Toshiaki*; Nagasaki, Shinya*; Kimura, Hideo; Takeda, Seiji ; Sekioka, Yasushi; Kato, Hiroyasu*; Akahori, Kuniaki*

Uncertainty found in the statistical data of Cs sorption coefficients was investigated. Careful data treatment indicated the major reason of data scatter was caused by the differences of the concentrations of co-existing ions and initial Cs concentrations. Analysis of the pH dependence of the data by adopting PHREEQC or MINEQL-TO which enable to treat ion exchange model coupled with the surface complexation model indicated the sorption coefficients could be represented for both cases obtained by batch method and diffusion method. In this analysis the same data set was used even for the extremely different experimental setup and the perturbation of environmental condition such as the Na concentration and pH brought strong influence on the data stability. The results also suggested that the scatter of the Cs sorption coefficient could be understandable and minimized through the analysis adopting mechanistic sorption model.