Publication Type
Journal
Journal Name
Journal of Phase Equilibria and Diffusion
Publication Date
Page Numbers
1 to 6
Volume
39
Abstract
The goal of this work was to understand the possible reactions between Ir and SiO2 contaminants in the presence of C (graphite insulation) and a cover gas for conditions representative of those for a module reduction and monitoring treatment at 1410 K. This treatment is for reduction of 238PuO2 fuel used in isotopic heat sources for space missions. A thermodynamic analysis has been performed for the relevant portions of the Ir-Si-C-O phase diagram using the CALPHAD method. The results show that over the range of relevant pressures of CO and CO2 in the argon cover gas, SiO2 is not stable in the presence of Ir. Levels of Si impurity dissolved in the iridium solid solution are expected to be up to 875 μg/g at or near the surface.
