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Title: Thermodynamic Analysis on Interactions of Silicon Dioxide with Iridium During Module Reduction and Monitoring Treatment

The goal of this paper was to understand the possible reactions between Ir and SiO 2 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 238PuO 2 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 CO 2 in the argon cover gas, SiO 2 is not stable in the presence of Ir. Finally, levels of Si impurity dissolved in the iridium solid solution are expected to be up to 875 μg/g at or near the surface.
 [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Phase Equilibria and Diffusion
Additional Journal Information:
Journal Name: Journal of Phase Equilibria and Diffusion; Journal ID: ISSN 1547-7037
ASM International
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE), Nuclear Facility Operations (NE-3); National Aeronautic and Space Administration (NASA)
Country of Publication:
United States
36 MATERIALS SCIENCE; CALPHAD; Ir-Si-C-O; phase diagram; thermodynamics
OSTI Identifier: