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Title: A thermal conductivity model for U-­Si compounds

Abstract

U 3Si 2 is a candidate for accident tolerant nuclear fuel being developed as an alternative to UO 2 in commercial light water reactors (LWRs). One of its main benefits compared to UO 2 is higher thermal conductivity that increases with temperature. This increase is contrary to UO 2, for which the thermal conductivity decreases with temperature. The reason for the difference is the electronic origin of thermal conductivity in U 3Si 2, as compared to the phonon mechanism responsible for thermal transport in UO 2. The phonon thermal conductivity in UO 2 is unusually low for a fluorite oxide due to the strong interaction with the spins in the paramagnetic phase. The thermal conductivity of U 3Si 2 as well as other U-­Si compounds has been measured experimentally [1-­4]. However, for fuel performance simulations it is also critical to model the degradation of the thermal conductivity due to damage and microstructure evolution caused by the reactor environment (irradiation and high temperature). For UO 2 this reduction is substantial and it has been the topic of extensive NEAMS research resulting in several publications [5, 6]. There are no data or models for the evolution of the U 3Si 2 thermalmore » conductivity under irradiation. We know that the intrinsic thermal conductivities of UO 2 (semi-conductor) and U 3Si 2 (metal) are very different, and we do not necessarily expect the dependence on damage to be the same either, which could present another advantage for the silicide fuel. In this report we summarize the first step in developing a model for the thermal conductivity of U-­Si compounds with the goal of capturing the effect of damage in U 3Si 2. Next year, we will focus on lattice damage. We will also attempt to assess the impact of fission gas bubbles.« less

Authors:
 [1];  [2]
  1. Idaho National Lab. (INL), Idaho Falls, ID (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Office of Nuclear Energy (NE)
OSTI Identifier:
1342838
Report Number(s):
LA-UR-16-27736
TRN: US1701909
DOE Contract Number:  
AC52-06NA25396
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; URANIUM SILICIDES; THERMAL CONDUCTIVITY; ACCIDENT-TOLERANT NUCLEAR FUELS; WATER MODERATED REACTORS; WATER COOLED REACTORS; SIMULATION

Citation Formats

Zhang, Yongfeng, and Andersson, Anders David Ragnar. A thermal conductivity model for U-­Si compounds. United States: N. p., 2017. Web. doi:10.2172/1342838.
Zhang, Yongfeng, & Andersson, Anders David Ragnar. A thermal conductivity model for U-­Si compounds. United States. doi:10.2172/1342838.
Zhang, Yongfeng, and Andersson, Anders David Ragnar. Thu . "A thermal conductivity model for U-­Si compounds". United States. doi:10.2172/1342838. https://www.osti.gov/servlets/purl/1342838.
@article{osti_1342838,
title = {A thermal conductivity model for U-­Si compounds},
author = {Zhang, Yongfeng and Andersson, Anders David Ragnar},
abstractNote = {U3Si2 is a candidate for accident tolerant nuclear fuel being developed as an alternative to UO2 in commercial light water reactors (LWRs). One of its main benefits compared to UO2 is higher thermal conductivity that increases with temperature. This increase is contrary to UO2, for which the thermal conductivity decreases with temperature. The reason for the difference is the electronic origin of thermal conductivity in U3Si2, as compared to the phonon mechanism responsible for thermal transport in UO2. The phonon thermal conductivity in UO2 is unusually low for a fluorite oxide due to the strong interaction with the spins in the paramagnetic phase. The thermal conductivity of U3Si2 as well as other U-­Si compounds has been measured experimentally [1-­4]. However, for fuel performance simulations it is also critical to model the degradation of the thermal conductivity due to damage and microstructure evolution caused by the reactor environment (irradiation and high temperature). For UO2 this reduction is substantial and it has been the topic of extensive NEAMS research resulting in several publications [5, 6]. There are no data or models for the evolution of the U3Si2 thermal conductivity under irradiation. We know that the intrinsic thermal conductivities of UO2 (semi-conductor) and U3Si2 (metal) are very different, and we do not necessarily expect the dependence on damage to be the same either, which could present another advantage for the silicide fuel. In this report we summarize the first step in developing a model for the thermal conductivity of U-­Si compounds with the goal of capturing the effect of damage in U3Si2. Next year, we will focus on lattice damage. We will also attempt to assess the impact of fission gas bubbles.},
doi = {10.2172/1342838},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Feb 02 00:00:00 EST 2017},
month = {Thu Feb 02 00:00:00 EST 2017}
}

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