Measurement of 137Cs in dust from steel scrap smelting

This paper deals with the measurement of 137Cs content in dust produced during steel scrap smelting and in the material produced from recycling the dust to recover the zinc oxide component. The measured samples have different densities and chemical compositions. The addition of radioactive standards to this kind of material to prepare a calibration standard is rather difficult. A theoretical analysis of the attenuation coefficient for this material together with its experimental measurement, show a linear relationship between the coefficient and density independent of chemical composition that allows the use of a soil sample to prepare calibration standards. An analysis of the validity of the method, as well as the development of a density correction factor is detailed. This factor is calculated incorporating the linear relationship between attenuation coefficient and density to the integral representing detection efficiency, and evaluating the integral by means of a Monte-Carlo program.