Oxidation and Release of Ruthenium from Short Fuel Rods above 1500 °C

A series of tests to study the chemical and physical behaviour of ruthenium released from fuel segments at high temperatures in air and vapour atmosphere were performed. The experiments in air atmosphere showed, that the partial pressures of the released Ru-oxides was two orders of magnitudes lower compared to those measured in the tests with Ru-powder diluted in a ZrO2 matrix. It was found that ruthenium was not released in steam atmosphere in the examined temperature range. Furthermore, the temperature dependence of the deposition was detected by XRF analysis.