Determination of ~(135)Cs in nuclear power plant wastes by ICP-MS and k_0- NAA

摘要

A radiochemical method for the determination of ~(135)Cs in radioactive wastes has been adopted/developed. For the separation of cesium from other elements ammo-nium-molybdophosphate precipitation and cation exchange chromatography were used. The chemical yield of the method was about 60-100 %. ~(135)Cs was measured by two methods. In neutron activation analysis (NAA), Cs was irradiated with reactor neutrons. ~(136)Cs was detected by gamma spectrometry, wherefrom the activity/mass of ~(135)Cs was calculated according to the k_0-standardization technique. The Cs containing fractions were measured by inductive coupled plasma mass spectrometry, as well. NAA and ICP-MS techniques were comparatively evaluated and a good agreement between the results was found. The activity concentration of ~(135)Cs in a couple of waste samples originating from VVER-440 type nuclear reactors was in the range of 1-5 Bq L~(-1) (20-120 ng L~(-1)) while ~(137)Cs activity concentrations varied between 0.1 and 1 MBq L~(-1).