Special Features of the Distribution of Point Defects Inside Uranium Dioxide Fuel Grains with the Formation of the Rim Layer

Abstract

The results of a simulation of the behavior of vacancies and interstitial atoms in uranium-dioxide fuel at temperature corresponding to the conditions under which a fine-grain structure forms are presented. It is shown that the distribution of point defects near grain boundaries and near line dislocations can be strongly nonuniform with differing spatial distribution of vacancies and intersitial atoms. Such a distribution of point defects can explain the experimentally observed grain-size dependence for threshold burnup at which fuel reconstruction starts.