J. Rory Kennedy

An Electromotive Force Measurement System for Alloy Fuels

The development of advanced nuclear fuels requires a better understanding of the transmutation and micro-structural evolution of the materials. Alloy fuels have the advantage of high thermal conductivity and improved characteristics in fuel-cladding chemical reaction. However, information on thermodynamic and thermophysical properties is limited. The objective of this project is to design and build an experimental system to measure the thermodynamic properties of solid materials from which the understanding of their phase change can be determined. The apparatus was used to measure the electromotive force (EMF) of several materials in order to calibrate and test the system. The EMF of chromel was measured from 100°C to 800°C and compared with theoretical values. Additionally, the EMF measurement of Ni-Fe alloy was performed and compared with the Ni-Fe phase diagram. The prototype system is to be modified eventually and used in a radioactive hot-cell in the future.Copyright

Characterization of Phases Formed Between U-Pu-X Fuels and Fe-Based Cladding

Uranium-plutonium-zirconium (U-Pu-Zr) and uranium-plutonium-molybdenum (U-Pu-Mo) fuels, known for their high burnup and good thermal response, have been considered as candidate fuels for advanced fast reactors. During their lifetime in the reactor, irradiation in combination with high temperatures can result in swelling of the fuel and its interaction with the cladding. As a result of the complex fuel-cladding chemical interaction (FCCI), integrity of fuel and cladding could be compromised and therefore should be comprehensively examined. As part of the fuel cycle research and development (FCRD) program, formation of intermetallic phases within fuel-cladding interaction zones was investigated in scanning electron microscope (SEM) and transmission electron microscope (TEM).

Evaluation of Uncertainties of One-Directional Analytical Model for Thermoreflectance Technique

One dimensional (1-D) analytical models are generally used for the evaluation of thermal effusivity of film or substrate in thermoreflectance measurement. However, the range of uncertainties associated with the 1-D assumptions needs to be quantified in order to determine the applicability of 1-D models. In the current study, a two-dimensional (2-D) numerical model was created in a commercial software package, COMSOL, to investigate the difference of results obtained by 1-D or 2-D models. The analysis used a frequency lock-in strategy and the result was verified by a comparison of 1-D numerical simulation to 1-D theoretical values. Parametric studies were performed by considering film thickness, heating laser radius, volumetric heating, thermal resistance between layers, and anisotropic thermal conductivities. The results and conclusions provide a general guidance and reference for the parametric design of thermoreflectance measurements.Copyright