Browsing by Author "Iso-Markku, Taneli"

As more nuclear power plants around the world face shut down and decommissioning in coming years, a need for methods to separate and analyse difficult-to-measure radionuclides is increasing. This work presents a brief overview of difficult-to-measure radionuclides and waste types of interest to Finnish nuclear power plant operators, with various methods developed to analyse them. Also included is information about research and analysis methods used by various Finnish organizations. Aside from literature overview, the results from laboratory work that was conducted are also included. An analytical method to simultaneously determine 55Fe and 63Ni in pressure vessel steel from BWR and VVER type reactors was tested. The method consisted of separation of iron and nickel from other metals and each other by hydroxide precipitation and anionic ion exchange chromatography, followed by purification of nickel with dimethylglyoxime complexation. Poor recoveries and low decontamination factor of 60Co led to abandonment of the method and adoption of different separation procedure based on anion exchange in HCl-acetone medium. In the second method Fe and Ni were separated from cobalt and each other by loading them to anion exchange column that had been preconditioned with a 9:1 mixture of acetone and HCl. Iron forms a complex with acetone that is not absorbed on anion exchange resin, while nickel and cobalt are both absorbed. Nickel was eluted with a 7:2 mixture of acetone and HCl, separating it from cobalt. Radioactivity of 55Fe and 63Ni was determined with liquid scintillation counting, while chemical yield was determined with atomic emission spectroscopy.