The fracture surfaces of three A533-B pressure-vessel steels have been analyzed using Auger analysis scanning electron microscopy and X-ray microanalysis. The steels included both weld and plate materials with differing radiation sensitivity. The unirradiated specimens were fractured under different conditions to give both ductile and brittle failure modes. The research showed that the copper and carbon concentrations were higher at the fracture surfaces. Very fine precipitates of molybdenum, phosphorus, and sulfur were observed on ductile fracture surfaces of all materials. However, the amount and type of precipitates varied among materials. Auger analysis and X-ray microanalysis provided consistent results and allowed detection of most of the impurity or alloying elements which have been related to radiation sensitivity of A533-B steels.