FIRST PRINCIPLES STUDY OF THERMAL CONDUCTIVITY OF NUCLEAR FUEL MATERIALS
13th International Conference on CANDU Fuel - 2016 Aug. 15-18


Presented at:
13th International Conference on CANDU Fuel
2016 Aug. 15-18
Location:
Kingston, ON Canada
Session Title:
None

Authors:
B. Szpunar (University of Saskatchewan)
L. Malakkal (University of Saskatchewan)
E. Jossou (University of Saskatchewan)
D. Oladimeji (University of Saskatchewan)
J. Ranasinghe (University of Saskatchewan)
I. Rossland (University of Saskatchewan)
J.A. Szpunar (University of Saskatchewan)
  

Abstract

Recent nuclear accident in Fukushima clearly illustrates the risks associated with the present design of reactors based on pure uranium oxide fuel and justify the research towards Accident Tolerant Fuel (ATF). ATF are fuels with enhanced thermal conductivity, which can withstand the loss of coolant for a long time by allowing faster dissipation of heat, thus lowering the centerline fuel temperature and preventing the melting of fuel. Moreover the nuclear power industry has an interest in using ThO2 as an alternate to UO2 since it does not oxidize, which prevents the thermal conductivity degradation in nuclear accident where steam ingress occurs. We have demonstrated previously that the phonon contribution to the thermal conductivity of thoria can be well reproduced using a simplified Slack model [1] with the input parameters evaluated from the first principles calculation. However in more detailed studies of the effect of composition and structural changes on thermal conductivity more accurate method is needed. Phonon–phonon scattering plays a dominant role in the lattice thermal conductivity. BTE can very well capture the phonon-phonon scattering and can accurately predict the lattice thermal conductivity without any assumptions. Therefore we investigate thermal conductivity of future nuclear fuel materials by solving Boltzmann Transport Equation (BTE) within Quantum ESPRESSO code implementation. The new calculations are compared with previous results for thoria [1]. Additionally we expand our simulation to studies of the effect of oxidation and structural changes on the thermal conductivity of traditional nuclear fuel and inert matrix fuel. Spark Plasma Sintering (SPS) is used to prepare the pellets and experiment using Direct Laser Flash (DLF) technique is used to measure the thermal conductivity as a function of temperature for the future nuclear material. 1. Szpunar B., Szpunar J.A., Sim Ki-Seob, J. Phys. and Chem. Solids, 90 (2016) 114-120.

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