Untersuchungen zum Verhalten von beschichteten Brennstoffteilchen und Kugelbrennelementen bei Störfalltemperaturen

A post irradiation annealing test apparature was constructed for the measurement of fission gas release at temperatures similar to those to be reached in a HTR during a hypothetical accident. From examinations with existing apparatures up to temperatures of 1800°C results were available about the load capacity of coated particles as well as knowledges about fission gas release and defect behaviour. These results were used to plan a series of annealing tests with spherical fuel elements up to 25OO°C. It could be shown that the (U, Th)O$_{2}$-particles with high burn up will fail during maximum core heat up of a HTR only after some hours at temperatures above 2400°C