Determination of ⁹³Mo in Radioactive Samples of Sulfuric Acid Media from Nuclear Facilities

Abstract

93 Mo is an important radionuclide in view of radioactive waste repository because of its long half-life and high mobility in the environment. 93 Mo decays by electron capture without any measurable gamma ray emission. The concentration of 93 Mo in most of the radioactive waste is many orders of magnitude lower than the major activation product radionuclides, which makes the accurate determination of 93 Mo a big challenge. A new analytical method for the determination of 93 Mo in sulfuric acid media from nuclear power reactor was developed. 93 Mo was separated from most of the radionuclides by cation exchange chromatography followed by the removal of sulfate by CaSO 4 precipitation. A further purification of 93 Mo, especially from anion species of 51 Cr and 125 Sb, was achieved by anion exchange chromatography and a short alumina column separation. The chemical yield of 93 Mo in the entire separation procedure reached about 75%, and the decontamination factors for all potential interfering radionuclides were 1.5 × 10 6 −1.6 × 10 8 . The purified 93 Mo was measured by liquid scintillation counting through counting its low-energy Auger electrons. A detection limit of 2 mBq/g for 93 Mo in 50 g sample was achieved by this method, which enables the quantitative determination of 93 Mo in most of the radioactive samples in the decommissioning waste and coolant water of nuclear power reactors. The developed method has been successfully applied to determine 93 Mo in coolant water of nuclear power reactors, providing a robust analytical approach of 93 Mo for the radiological characterization of radioactive wastes. 93