Development of a radiotracer method for the determination of the mixing quality in the solidification of simulated α-wastes in ceramic materials

The homogenization processing stage has an important function in the solidification of radioactive wastes containing alpha-emitters in alumino-silicate ceramics. It is carried out in a trough kneader with sigma-kneading blades and discharge scroll operated in stages. A radionuclide technical measuring procedure was developed to determine the degree of homogenization and the mixture of the product. The method permits a continuous, contact-free detection of the concentration balance of a previously labelled component of the mixture as well as a non-destructive quality control of the product. For this purpose 20 radiation detectors with automatic data recording were fitted to the kneader. A measuring station was developed for studies of homogeneity of the final product, which enables 2000 samples per hour to be measured. The radiotracers used were 56Mn and 139Ba in water soluble and insoluble chemical compounds. Following detailed standardization trials to establish the degree of accuracy of the method the relationships between relevant mixing parameters and local conditions of homogenization were studied in the ceramic material systems. (orig.)