The membrane method combined with complexation was applied for hazardous wastes containing radioactive substance processing. Such complexing agents like soluble chelating polymers and cyanoferrates of transient metals, tested and selected in the laboratory, were used to bind radioactive ions and to enlarge the separated molecule size. The preliminary pilot plant experiments are presented with installation equipped with a ceramic 23-channel module, cut-off 8 kD. The experiments were performed with model solutions and original radioactive wastes. They showed the feasibility of a UF/complexation hybrid method for reduction of long-lived radioisotope concentration in the effluent (permeate). The radioactive substances concentrated in a small volume can be directly fossilized.