In the context of two reactor decommissioning projects, radioactive slurry from concrete cutting was collected in the retention pond (RHB) at the Paul Scherrer Institute, along with radioactive drain outlets. Additionally, there are active residues from former operations. The task was to determine the nuclide vector of the radioactive slurry before final disposal. Due to the slurry from neutron-activated concrete, activation products, like 55 Fe, 60 Co, 63 Ni, 133 Ba, 152 Eu, 154 Eu and 155 Eu can be expected. Accumulated drain outlets from laboratories, where work with radioactive substances is being done, were expected to contain 22 Na, 60 Co, 134 Cs, 137 Cs, 133 Ba, 152 Eu, 154 Eu, 155 Eu, 241 Am, 239/240 Pu, 241 Pu, 244 Cm, 234 U, 235 U, 238 U, 230 Th, 232 Th and 90 Sr. For further clarification, 3 H and 14 C in the water and in the organic phase had to be measured as well. This work gives an overview about the slurry dissolution techniques, the radiochemical separation methods and activity concentrations of the nuclide vector. Further processing of the slurry is also discussed.