Experimental Determination of the Characteristics of Coolant-Born Corrosion Products in the Primary Circuit of WWER-1000

NPP Investigation of the specific characteristics of high temperature multiphase system of the reactor coolant, the contacting construction materials and their oxide products is important for the quantitative evaluation of the water chemistry influence on the radionuclide transport in the primary circuit of WWER-1000 NPP. The research program included determination the phase, elemental and radiochemical composition of the circulating corrosion products taken from the different sampling points of the primary system of the unit VI of NPP Kozloduy. Wide range of analytical methods including SEM, EDX, RFA, RDA, HEED and others, were used. The experimental data confirm that the main material carriers of the long-live radioactivity related to the radioactive field around the primary circuit are the mixed spinels of the type NixFe1-x+yCr2-yO4 with typical values of the Ni/Fe-ratio of 0.14-0.25 and the metallic Ni. (author)