Thermal Property Characterization, Modeling, and Theory in Extreme Environments: Structure - Thermal Property Relationships
Sponsored by: TMS Structural Materials Division, TMS: Nuclear Materials Committee
Program Organizers: Janelle Wharry, Purdue University; Mukesh Bachhav, Idaho National Laboratory; Marat Khafizov, Ohio State University; Eric Lass, University of Tennessee-Knoxville; Vikas Tomar, Purdue University; Tiankai Yao, Idaho National Laboratory; Cody Dennett, Commonwealth Fusion Systems; Karim Ahmed, Texas A&M University
Thursday 2:00 PM
March 18, 2021
Room: RM 53
Location: TMS2021 Virtual
Session Chair: Marat Khafizov, Ohio State University; Tiankai Yao, Idaho National Laboratory
2:00 PM
Mesoscale Modeling of the Effective Thermal Conductivity of a UO2-Mo Composite Nuclear Fuel: Karim Ahmed1; Fergany Badry1; 1Texas A&M University
The effective thermal conductivity of nuclear fuels strongly depends on the underlying microstructure. We developed a novel mesoscale model to investigate this relationship in UO2-Mo fuel composites. The model accounts for the thermal resistance of the UO2-Mo interface and able to predict the effective conductivity of the fuel for different fuel compositions, microstructures, and temperatures. The model has been implemented in the MOOSE framework. The model predicts higher effective thermal conductivity of UO2- Mo fuel for microstructures with continuous distribution of second phase than microstructures with dispersed second phase particles for the same volume fraction and temperature. The model results agree well with the experimental data from literature.
2:20 PM
Thermal and Mechanical Properties of Hafnon (HfSiO4), Theory and Experiments: Zhidong Ding1; Mackenzie Ridley1; Jeroen Deijkers1; Naiming Liu1; Md. Shafkat Hoque1; John Gaskins1; Mona Zebarjadi1; Patrick Hopkins1; Haydn Wadley1; Elizabeth Opila1; Keivan Esfarjani1; 1University of Virginia
Hafnium orthosilicate (HfSiO4: hafnon) has been proposed as an environmental barrier coating (EBC) material to protect silicon and silicon-based ceramic materials at high temperatures and as a candidate dielectric material in microelectronic devices. It can naturally form at the interface between SiO2 and hafnia (HfO2). In this work, the thermophysical properties of hafnon such as thermal expansion, elastic moduli and thermal conductivity, have been investigated using a combination of density functional theory (DFT) calculations and experimental assessments.The predicted thermal conductivity from Boltzmann transport theory is approximately 16.1 W/m.K at 300K, while that that of our samples using both hot disk and laser flash measurements gave a value of 13.3 W/m.K. Mechanical properties were measured using nanoindentation techniques. Overall calculated properties agree relatively well with the experimental characterizations, paving the way for the future investigation of the thermomechanical properties of other oxides or silicates.
2:40 PM Invited
First-principles Modeling of High Temperature Irradiation Resistant Thermocouple (HTIR-TC) Performance and Oxidation: Lan Li1; Ember Sikorski1; Richard Skifton2; Brian Jaques1; 1Boise State University; 2Idaho National Laboratory
Instrumentation is needed to characterize experiments in research reactors that can operate at over 1000˚C. To meet this need, Idaho National Laboratory has been developing High Temperature Irradiation Resistant Thermocouples (HTIR-TCs) composed of Mo and Nb thermoelements separated by Al2O3 insulation. Using Ab initio Molecular Dynamics and Boltzmann Transport Equations, we calculated the Seebeck emf, a thermoelectric property, to measure the materials’ voltage response to temperature change in HTIR-TCs. With this method, HTIR-TC performance were predicted with respect to temperature, transmutation, and oxidation. Accelerated by high temperature, oxygen could diffuse into the thermoelements from the insulation or the air or water present in the reactor. To better understand the possible causes of thermoelement oxidation, we investigated Mo-Al2O3 and Nb-Al2O3 interfaces and the Mo and Nb surfaces in the presence of O2 and H2O at high temperatures. Diffusion mechanisms and their effect on HTIR-TC performance were also investigated.
3:10 PM
Multiphysics Mesoscale Modeling of Ablative Thermal Protection Systems: Marina Sessim1; Linuyan Shi1; Simon Phillpot1; Michael Tonks1; 1University of Florida
The Phenolic Impregnated Carbon Ablator (PICA) is NASA’s heritage Thermal Protection System (TPS) material for atmospheric entry of space capsules. It has been successfully tested in previous missions such as Stardust, and it is a potential candidate for future deep-space missions. PICA is composed of carbon fibers embedded in a phenolic resin, which is transformed into char upon ablation. We are developing a multiphysics mesoscale ablation model to better understand the impact of the PICA microstructure on its thermal performance. This model is developed using the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework, a C++ finite element framework developed by the Idaho National Laboratory. The scope of this presentation is to introduce the ablation model, which employs the phase-field method coupled with heat conduction and chemical reaction kinetics. We demonstrate the model capabilities by predicting the thermal performance of a single carbon fiber and multiple fibers under high temperatures.
3:30 PM
An Experimentally Validated Mesoscale Model for the Effective Thermal Conductivity of U-Zr Fuels: Karim Ahmed1; Fergany Badry1; Sean McDeavitt1; 1Texas A&M University
The effective thermal conductivity of nuclear fuels strongly depends on the underlying microstructure. We conducted a combined experimental and computational work to investigate this relationship in UZr fuels with different theoretical densities. A microstructure informed model was developed to simulate effective thermal conductivity of UZr fuels at different temperatures and porosity levels. The model accounts for the thermal resistance of the interfaces and able to predict the effective conductivity of the fuel for different fuel densities, microstructures, and temperatures. The model has been implemented in the MOOSE framework. A companion experimental work was also conducted to correlate the effective thermal conductivity of U-10Zr pellets measured using the laser flash method and the underlying microstructure. The model was validated against the experimental data obtained in this work.