| AVS 63rd International Symposium & Exhibition | |
| Applied Surface Science | Tuesday Sessions |
| Session AS-TuP |
| Session: | Applied Surface Science Division Poster Session |
| Presenter: | Rachel Seibert, Illinois Institute of Technology |
| Authors: | R. Seibert, Illinois Institute of Technology C. Parish, Oak Ridge National Laboratory P. Edmondson, Oak Ridge National Laboratory K. Terrani, Oak Ridge National Laboratory J. Terry, Illinois Institute of Technology |
| Correspondent: | Click to Email |
High temperature gas cooled reactors (HTGRs) may use tristructural-isotropic (TRISO) coated nuclear fuel particles. Fuel performance is limited by the interaction of fission products with the barrier SiC layer. In particular, Ag is released from intact TRISO fuel, and Pd may locally corrode the SiC. Additionally, uranium and plutonium migration are of interest. An understanding of the reaction mechanisms and kinetics of these interactions under normal operation as well as accident conditions is critical for the development of advanced nuclear reactors. We have studied TRISO particles produced at ORNL under the Advanced Gas Reactor fuel program. The fuel was irradiated at the Advanced Test Reactor at Idaho National Laboratory. The local chemical structure of three TRISO SiC shells was examined through X-ray absorption fine structure spectroscopy (XAFS) at the Materials Research Collaborative Access beamline at the Advanced Photon Source. To complement these results, electron microscopy studies have been conducted on various samples prepared from these SiC fragments at the Low Activation Materials Development and Analysis (LAMDA) facility at ORNL. Specifically, samples were prepared from the inner, outer, and middle interfaces of the SiC fragment to obtain a full cross-sectional image of the fission product migration. These results have provided key information on the fission product transport behavior through irradiated SiC at varying temperatures. Knowledge of these reaction pathways will allow for better simulation of the long-term behavior of TRISO fuels. They may also suggest ways to modify the SiC layer to improve fuel performance and mitigate fission product release, which is critical for safety strategies required to commercialize HTGRs.