Technical Report NTB 85-18_19_20_21

Actinide Solubilities and Speciation in a Repository EnvironmentOrganic Complexing Agents in Low- and Medium-Level Radioactive WasteRadionuclide Sorption on Carbonate-Clayish RockRadionuclide Sorption on Concrete

The speciation and solubility of the actinides thorium (Th), uranium (U), neptunium (Np), plutonium (Pu) and americium (Am) have been calculated with variation of pH, the reduction potential (Eh) and the carbonate concentration. Speciation and solubility in groundwater from Valanginian marl (that is, pH 8 – 9.5, reducing conditions and with high carbonate concentrations) and in concrete porewaters (pH 12.5 – 13.5 and low carbonate concentrations) are discussed. The effects of strong complexing agents like DTPA and EDTA are also briefly commented.