Knudsen Cell-Mass Spectroscopic Studies of Strontium Vapour Pressures Over Strontium Oxide/Uranium Dioxide Mixtures and Solid Solutions

Abstract

High temperature, Knudsen cell-mass spectroscopic (KC-MS) experiments were performed to determine the volatility of strontium oxide dissolved in UO₂ fuel. KC-MS experiments were carried out with finely ground and pre-heated mixtures of SrO and UO₂ and "solid solutions" of SrO in UO₂, prepared using the sol-gel method. It was found that the main strontium gaseous species over these samples was Sr atoms. The KC-MS experiments showed that the vapour pressures of Sr over pre-heated-mixtures of SrO and UO₂, at high temperatures, were similar to those over pure SrO. The vapour pressures of Sr, over "sol-gel prepared solid solutions" of compositions SrO:UO₂ equal to 1:100 and 2:100 were similar to each other and to those reported over pure SrO by Lamoreaux et al. (for congruent vapourization); but were lower than those over pure SrO observed in this work, and over SrUO₃ reported by Huang et al. and Yamawaki et al.