Determination of the nuclide vector for decommissioning projects at PSI (Paul Scherrer Institute, Switzerland)

Abstract

Abstract 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 55Fe, 60Co, 63Ni, 133Ba, 152Eu, 154Eu and 155Eu can be expected. Accumulated drain outlets from laboratories, where work with radioactive substances is being done, were expected to contain 22Na, 60Co, 134Cs, 137Cs, 133Ba, 152Eu, 154Eu, 155Eu, 241Am, 239/240Pu, 241Pu, 244Cm, 234U, 235U, 238U, 230Th, 232Th and 90Sr. For further clarification, 3H and 14C 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.