ISO 8299:1993

The method is based on isotope ratio measurements in solutions by thermal ionization mass spectrometry. Includes the following steps: dilution, spike addition, isotope exchange chemistry, ion exchange purification/separation, preparation of filaments, mass spectrometric measurements and calculation of isotopic and elemental concentrations. Pu 238 is determined by means of alpha spectrometry if interferences from U 238 cannot be eliminated. Is applicable to solutions of irradiated fuels from boiling water or pressurized water reactors and, after modification of chemical separation and spike solution, also to other types of fuel.