Intrinsic Properties and Radiation Effects of ZrC
Zirconium carbide is an ultra-high temperature ceramic material with potential applications in extreme environments including those inside a nuclear reactor. We are studying the effects of stoichiometry, Hf, O and N impurities, carbon inclusions and microstructure on the thermal and mechanical properties and radiation damage evolution of ZrCx ceramics. This work is supported in part through an NSF grant and in collaboration with Drs. Fahrenholtz and Hilmas and students in the Ceramics Engineering program at Missouri S&T.
Underwater Gamma Ray Computed Tomography of Nuclear Fuel
We are designing and building an underwater gamma-ray tomography system to image test fuel irradiated in the Advanced Test Reactor at Idaho National Laboratories. This system will use both Co-60 transmission computed tomography and fission product emission tomography to acquire high-resolution 3D spatial information about the fuel structure and fission product distribution after irradiation. This project is supported by the Department of Energy's Nuclear Energy University Programs (NEUP). Dr. Graham is working with Dr. Hyoung-Koo Lee and students in the Nuclear Engineering program and Nick Woolstenhulme of INL.
Oxidation of SiC and Graphitic Materials
Dr. Graham's group is working with Dr. Haiming Wen in Materials Science and Missouri S&T on Department of Energy Nuclear Energy University Programs (NEUP) project to study oxidation behavoir in irradiated and unirradiated graphitic materials and surrogate TRISO fuel. Data and findings from this work will inform modeling and safety analysis of reactor materials and fuels used in high-temperature gas reactors (HTGRs).
Advanced Characterization Techniques
Students are working with Dr. Graham to develop advanced materials characterization apparatus which can be used to measure the thermal diffusivity in thin surface layers, light-element chemical depth profiles, electron phonon coupling coefficients in metals and alloys, and vacancy and small void defects. These techniques are helpful in collecting data on thin films, nuclear fuel coatings, and neutron and ion irradiated materials.
In-situ Ionoluminesence Studies of SrTiO3
Dr. Graham has been collaborating with Dr. Miguel Crespillo of the University of Tennessee, Knoxville to perform and analyze novel experiments using energetic light and heavy ions to simultaneously damage and electronically excite strontium titanate crystals at cryogenic temperatures. The ion induced luminescence signal from these experiments provides new insights into the kinetics of defect formation, recombination and complexation.
Enhancing the Mechanical Properties of Polymer Aerogels Through Irradiation
Our group is working with Dr. Chenglin Wu in Civil Engineering and Dr. Nicholas Leventis in Chemistry at Missouri S&T to enhance the hardness and stiffness of polyurea aerogels via in-pile gamma irradiation. So far we have seen improvements by up to 400% in mechancial properties in these high strength-to-weight ratio materials.