Crud Analytical Technique by abnormal high beam current using EPMA

To investigate the morphology and composition of the pure metallic material composing the crud, we tried to remove coolant impurities. We tried to increase the EPMA current to an abnormal intensity until the impurities contained in the crud were melted. The technique was applied by opening an adjustable aperture device for a gun alignment adjustment. As a result, it was confirmed that the impurities contained in the crud material disappeared and only the pure metal material remained. The shape and composition of the remained crud metal elements were analyzed, and the results are shown in this paper. The ratio of pure metal, compared to the volume of impurities and other water-soluble amorphous materials, is absolutely low in the entire volume of the crud. Fuel crud is generally composed of NiFe₂O₄, NiO, Ni⁰ etc. We tried to quantitative analyses the remaining metallic crud precipitate No1~4. We found NiFe₂O₄ at No1 specimen, and boll type pure Ni/Fe material at No3, also we can see Fe/Ni/O = 1/1/1 at No4 specimen. The results from this experiment may be different from the composition of crud.