INVESTIGATION OF FUEL STRUCTURE AND COMPOSITION AFTER IRRADIATION IN WER-440 TO BURNUP 70 MW·days/kg

摘要

The results of structural investigations performed on fuel and fission products - neodymium, xenon, and cesium - along the radius of a fuel kernel after irradiation in VVER-440 to burnup 70.2 MW·days/kg are presented. The radial distribution of neodymium is used to calculate the radial distribution of burnup and the accumulation of xenon and cesium. It is shown that a decrease of the xenon content in the fuel matrix as compared with the amount formed over the irradiation time is observed over the entire cross section of the pellet and is due to complete or partial fuel recrystallization occurring predominately along the boundaries of the initial grains and characterized by the formation of a fine-grain structure together with submicron and micron pores.