Application of the Veibull distribution to predict the extent of core depressurization for reactors of some types

Problem of predicting dispersion type fuel element depressurization used in research and high-temperature gas-cooled graphite-moderated reactors is considered with the application of statistic methods of reliability theory. Problems of choosing reference isotopes, from which yield a depressurization value must be determined, are discussed. Technique for determining the Veibull's distribution parameters for known and unknown sampling volumes are given as well as results of experiment when 6500 coated fuel elements were irradiated up to 13 % burn-up. The conclusion of the Veibull's distribution applicability for predicting radiation situation under conditions of maximum opened fuel surface has been drawn