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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 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.

Authors:
 [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
Publication Date:
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)
OSTI Identifier:
1460200
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Phase Equilibria and Diffusion
Additional Journal Information:
Journal Volume: 39; Journal Issue: 5; Journal ID: ISSN 1547-7037
Publisher:
ASM International
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CALPHAD; Ir-Si-C-O; phase diagram; thermodynamics

Citation Formats

Ohriner, Evan, and Yang, Ying. Thermodynamic Analysis on Interactions of Silicon Dioxide with Iridium During Module Reduction and Monitoring Treatment. United States: N. p., 2018. Web. doi:10.1007/s11669-018-0637-0.
Ohriner, Evan, & Yang, Ying. Thermodynamic Analysis on Interactions of Silicon Dioxide with Iridium During Module Reduction and Monitoring Treatment. United States. doi:10.1007/s11669-018-0637-0.
Ohriner, Evan, and Yang, Ying. Mon . "Thermodynamic Analysis on Interactions of Silicon Dioxide with Iridium During Module Reduction and Monitoring Treatment". United States. doi:10.1007/s11669-018-0637-0. https://www.osti.gov/servlets/purl/1460200.
@article{osti_1460200,
title = {Thermodynamic Analysis on Interactions of Silicon Dioxide with Iridium During Module Reduction and Monitoring Treatment},
author = {Ohriner, Evan and Yang, Ying},
abstractNote = {The goal of this paper 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. 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.},
doi = {10.1007/s11669-018-0637-0},
journal = {Journal of Phase Equilibria and Diffusion},
number = 5,
volume = 39,
place = {United States},
year = {2018},
month = {5}
}

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