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

Evan Ohriner; Ying Yang

doi:10.1007/s11669-018-0637-0

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

Evan Ohriner, Ying Yang

Microstructural Evolution Modeling

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

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.

Original language	English
Pages (from-to)	532-537
Number of pages	6
Journal	Journal of Phase Equilibria and Diffusion
Volume	39
Issue number	5
DOIs	https://doi.org/10.1007/s11669-018-0637-0
State	Published - Oct 1 2018

Funding

Acknowledgments Funding for this work was provided by the United States Department of Energy Office of Nuclear Facilities Management (NE-31) and the National Aeronautics and Space Administration Planetary Science Division. Oak Ridge National Laboratory is managed by UT-Battelle, LLC for the U.S. Department of Energy. Funding for this work was provided by the United States Department of Energy Office of Nuclear Facilities Management (NE-31) and the National Aeronautics and Space Administration Planetary Science Division. Oak Ridge National Laboratory is managed by UT-Battelle, LLC for the U.S. Department of Energy. This invited article is part of a special issue of the Journal of Phase Equilibria and Diffusion in honor of Prof. Zhanpeng Jin?s 80th birthday. The special issue was organized by Prof. Ji-Cheng (JC) Zhao, The Ohio State University; Dr. Qing Chen, Thermo-Calc Software AB; and Prof. Yong Du, Central South University. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

Keywords

CALPHAD, Ir-Si-C-O
phase diagram
thermodynamics

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10.1007/s11669-018-0637-0

Cite this

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title = "Thermodynamic Analysis on Interactions of Silicon Dioxide with Iridium During Module Reduction and Monitoring Treatment",

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.",

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AB - 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.

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

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