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Title: THERMAL CONDUCTIVITY OF POLYCRYSTALLINE ZIRCONIUM NITRIDE AS A FUNCTION OF TEMPERATURE, POROSITY, AND OXYGEN IMPURITY LEVEL

Abstract

The U.S. Department of Energy is currently investigating routes that will allow for a closed fuel cycle. One key benefit of a closed fuel cycle is significant reductions in the radiotoxicity of high-level waste via transmutation of minor actinides in fast spectrum reactors or accelerator driven systems. Mononitrides (MN, where M = Zr, U, Np, Pu, Am, Cm, etc.) are candidates for transmutation fuel materials due to significant radiation tolerance and high thermal conductivity, both important characteristics for high burn-up fuels. ZrN is of interest as a candidate matrix material for future dispersion fuels, a diluent in actinide-bearing fuels, and a surrogate material that enables efficient assessment of some trends in thermo-physical properties of mononitrides. ZrN-based, actinide-bearing nitride fuels, e.g. (Pu, Np, Am)N-36wt%ZrN, have been irradiated in the Advanced Test Reactor (ATR) at INL in the AFC-AE test and are scheduled for insertion in the Phenix reactor for the FUTURIX-FTA experiment. Pure ZrN matrix material is also scheduled for insertion in the FUTURIX-MI materials irradiation experiment. Therefore, it is important to understand the thermophysical properties of unirradiated polycrystalline ZrN as a function of porosity (density and pore distribution) as well as stoichiometry. Specific heat, thermal expansion and thermal diffusivity havemore » been measured in ZrN samples with different bulk densities and oxygen impurity levels. For the samples, thermal conductivity was calculated as the product of the bulk density, specific heat and thern1al diffusivity. Properties were measured over at least the temperature range of room temperature to 1200 C in samples with densities ranging from roughly 85 to 95% of theoretical density. Over this temperature range, the linear thermal expansion coefficient was {approx}10 x 10{sup -6}/C, specific heat increased from {approx}0.4 to 0.5 J/(g K), and thermal diffusivity increased from {approx}3 to 6 mm{sup 2}/s. For the densities studied, this corresponded to thermal conductivity increasing from {approx}7 to 20 W/(m K) from room temperature to 1200 C. As expected, thermal conductivity of the polycrystalline ZrN varied with density and a significant effect on the measured properties was observed for samples with different oxygen impurity levels. The implications of the observed trends in thermophysical properties with porosity and oxygen impurity level will be discussed in the context of nitride fuel fabrication and performance as well as with respect to fuel property characterization.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
OSTI Identifier:
985881
Report Number(s):
LA-UR-07-0703
TRN: US1006262
DOE Contract Number:
AC52-06NA25396
Resource Type:
Conference
Resource Relation:
Conference: GLOBAL 2007: ADVANCED NUCLEAR FUEL CYCLES AND SYSTEMS ; 200709 ; BOISE
Country of Publication:
United States
Language:
English
Subject:
36; ACCELERATORS; ACTINIDES; BULK DENSITY; FABRICATION; FUEL CYCLE; IRRADIATION; MATRIX MATERIALS; NITRIDES; NUCLEAR FUELS; OXYGEN; PHENIX REACTOR; POROSITY; RADIATIONS; SOLVENTS; SPECIFIC HEAT; STOICHIOMETRY; TEST REACTORS; THERMAL CONDUCTIVITY; THERMAL DIFFUSIVITY; THERMAL EXPANSION; TRANSMUTATION; WASTES; ZIRCONIUM NITRIDES

Citation Formats

STANEK, CHRISTOPHER R., MCCLELLAN, KENNETH J., MORALES, LUIS A., BYLER, DARRIN D., VOIT, STEWART L., and HENDERSON, JACK B. THERMAL CONDUCTIVITY OF POLYCRYSTALLINE ZIRCONIUM NITRIDE AS A FUNCTION OF TEMPERATURE, POROSITY, AND OXYGEN IMPURITY LEVEL. United States: N. p., 2007. Web.
STANEK, CHRISTOPHER R., MCCLELLAN, KENNETH J., MORALES, LUIS A., BYLER, DARRIN D., VOIT, STEWART L., & HENDERSON, JACK B. THERMAL CONDUCTIVITY OF POLYCRYSTALLINE ZIRCONIUM NITRIDE AS A FUNCTION OF TEMPERATURE, POROSITY, AND OXYGEN IMPURITY LEVEL. United States.
STANEK, CHRISTOPHER R., MCCLELLAN, KENNETH J., MORALES, LUIS A., BYLER, DARRIN D., VOIT, STEWART L., and HENDERSON, JACK B. Wed . "THERMAL CONDUCTIVITY OF POLYCRYSTALLINE ZIRCONIUM NITRIDE AS A FUNCTION OF TEMPERATURE, POROSITY, AND OXYGEN IMPURITY LEVEL". United States. doi:. https://www.osti.gov/servlets/purl/985881.
@article{osti_985881,
title = {THERMAL CONDUCTIVITY OF POLYCRYSTALLINE ZIRCONIUM NITRIDE AS A FUNCTION OF TEMPERATURE, POROSITY, AND OXYGEN IMPURITY LEVEL},
author = {STANEK, CHRISTOPHER R. and MCCLELLAN, KENNETH J. and MORALES, LUIS A. and BYLER, DARRIN D. and VOIT, STEWART L. and HENDERSON, JACK B.},
abstractNote = {The U.S. Department of Energy is currently investigating routes that will allow for a closed fuel cycle. One key benefit of a closed fuel cycle is significant reductions in the radiotoxicity of high-level waste via transmutation of minor actinides in fast spectrum reactors or accelerator driven systems. Mononitrides (MN, where M = Zr, U, Np, Pu, Am, Cm, etc.) are candidates for transmutation fuel materials due to significant radiation tolerance and high thermal conductivity, both important characteristics for high burn-up fuels. ZrN is of interest as a candidate matrix material for future dispersion fuels, a diluent in actinide-bearing fuels, and a surrogate material that enables efficient assessment of some trends in thermo-physical properties of mononitrides. ZrN-based, actinide-bearing nitride fuels, e.g. (Pu, Np, Am)N-36wt%ZrN, have been irradiated in the Advanced Test Reactor (ATR) at INL in the AFC-AE test and are scheduled for insertion in the Phenix reactor for the FUTURIX-FTA experiment. Pure ZrN matrix material is also scheduled for insertion in the FUTURIX-MI materials irradiation experiment. Therefore, it is important to understand the thermophysical properties of unirradiated polycrystalline ZrN as a function of porosity (density and pore distribution) as well as stoichiometry. Specific heat, thermal expansion and thermal diffusivity have been measured in ZrN samples with different bulk densities and oxygen impurity levels. For the samples, thermal conductivity was calculated as the product of the bulk density, specific heat and thern1al diffusivity. Properties were measured over at least the temperature range of room temperature to 1200 C in samples with densities ranging from roughly 85 to 95% of theoretical density. Over this temperature range, the linear thermal expansion coefficient was {approx}10 x 10{sup -6}/C, specific heat increased from {approx}0.4 to 0.5 J/(g K), and thermal diffusivity increased from {approx}3 to 6 mm{sup 2}/s. For the densities studied, this corresponded to thermal conductivity increasing from {approx}7 to 20 W/(m K) from room temperature to 1200 C. As expected, thermal conductivity of the polycrystalline ZrN varied with density and a significant effect on the measured properties was observed for samples with different oxygen impurity levels. The implications of the observed trends in thermophysical properties with porosity and oxygen impurity level will be discussed in the context of nitride fuel fabrication and performance as well as with respect to fuel property characterization.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jan 31 00:00:00 EST 2007},
month = {Wed Jan 31 00:00:00 EST 2007}
}

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