Study on solubility of transuranium elements

Moriyama, Hirotake*

In support of the safety assessment of geologic disposal of high level radioactive wastes, the solubility of transuranium elements was studied. The solubility of plutonium was measured in an aqueous solution of pH3-8 under reducing conditions, and the obtained results were well explained by considering the presence of the solution species of Pu(III) in equilibrium with the solid phase of PuO(am). Also, systematic behavior of hydrolysis constants of actinide ions was studied with the help of a simple hard sphere model. The literature data of the hydrolysis constants of actinide ions were analyzed by the model and systematic trends were explained by taking into account the effective charges of actinide ions. Such a model is useful to check the experimental data and to predict the unknown data from a systematic point of view.