TY - JOUR

T1 - Thermal conductivity variation in uranium dioxide with gadolinia additions

AU - Qin, Meng

AU - Middleburgh, Simon

AU - Cooper, M. W. D.

AU - Rushton, Michael

AU - Puide, Mattias

AU - Kuo, E. Y.

AU - Grimes, Robin W.

AU - Lumpkin, Gregory R.

PY - 2020/11

Y1 - 2020/11

N2 - By combining experimental observations on Gd doped fuel with a theoretical understanding, the variation in thermal conductivity with Gd concentration and accommodation mechanism has been modelled. Four types of Gd accommodation mechanisms have been studied. In UO2−x, isolated substitutional Gd3+ ions are compensated by oxygen vacancies and defect clusters. In UO2, isolated substitutional Gd3+ ions are compensated by U5+ ions and defect clusters. The results indicate that defect clusters can be considered as less effective phonon scatterers and therefore result in less thermal conductivity degradation. The thermal conductivity predicted for UO2 with defect clusters is in good agreement with experimental data for UO2 with 5 wt% Gd2O3. This supports the previous theoretical results that Gd is accommodated through defect clusters in UO2 in the presence of excess oxygen.

AB - By combining experimental observations on Gd doped fuel with a theoretical understanding, the variation in thermal conductivity with Gd concentration and accommodation mechanism has been modelled. Four types of Gd accommodation mechanisms have been studied. In UO2−x, isolated substitutional Gd3+ ions are compensated by oxygen vacancies and defect clusters. In UO2, isolated substitutional Gd3+ ions are compensated by U5+ ions and defect clusters. The results indicate that defect clusters can be considered as less effective phonon scatterers and therefore result in less thermal conductivity degradation. The thermal conductivity predicted for UO2 with defect clusters is in good agreement with experimental data for UO2 with 5 wt% Gd2O3. This supports the previous theoretical results that Gd is accommodated through defect clusters in UO2 in the presence of excess oxygen.

KW - Gadolinium accommodation mechanism

KW - Gd2O3-Doped UO2

KW - Molecular dynamics simulations

KW - Thermal conductivity

U2 - 10.1016/j.jnucmat.2020.152258

DO - 10.1016/j.jnucmat.2020.152258

M3 - Article

VL - 540

JO - Journal of Nuclear Materials

JF - Journal of Nuclear Materials

SN - 0022-3115

M1 - 152258

ER -