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)
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
 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 .
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
1. Szpunar B., Szpunar J.A., Sim Ki-Seob, J. Phys. and Chem.