2017 | AFC ACCOMPLISHMENTS 152 The goal of this project is to develop a predictive BISON capability enabling coupled thermal-mechanical-chemical- diffusion analysis of uranium, plutonium and zirconium metallic fuels.The fully-coupled capability will model all key aspects of metallic fuel performance under irradiation conditions of advanced reactors, such as species transport, fuel-clad-mechanical interaction including crackling, fuel-clad chemical interactions, and swelling with appropriate phase dependent properties.Advanced calibration methodologies developed by Nuclear Energy Advanced Modeling and Simulation (NEAMS) program are used to calibrate the capability against available data. Gaps in modeling are identified and solutions are being developed, and experimental needs are continually determined. Project Description: The use of metallic fuels in these new nuclear technology concepts has been gaining renewed attention. Metallic fuels are attractive since they have higher thermal conductivity with a highly conductive gap that enables the fuel to operate at lower temperatures with reduced stored energy.Additional benefits of metallic fuels include a more favorable neutron economy, higher fuel densities, and easier fabrication and reprocessing. Generally speaking, the thermo- mechanical-chemical-diffusion behavior of a nuclear fuel pellet or rod involves a complex system of interdependent processes as a result of the high thermal-power densities and irradiation effects.All of the physics are driven by processes occurring at the microstructure level (i.e., at the grain or subgrain scale).The migration of porosity, fuel constituents, and fission products cause fuel restructuring in metal fuels. Irradiation induced effects such as fission product generation, as well as chemical interactions, change the material properties of the fuel and cladding. Swelled fuel causes mechanical interaction between fuel and cladding that can produce stresses and deformation in addition to the stress caused by internal pressure in the fuel. Despite the fact that many researchers have developed multiple computer codes, a robust predictive capability for quantifying fuel behavior and constituent distribution in metallic fuels and the associated uncertainty is still unavailable; large uncertainties and scatter still exist in predictions. A BISON capability enabling coupled thermal-mechanical-chemical-diffusion analysis of uranium, plutonium and zirconium metallic fuels is necessary and required for the development of advanced fuel concepts, and licensing of advanced reactor concepts. Such a capability provides a tool not only for design and licensing but inexpensively test new simulation-aided concepts prior expensive experimentation, optimize the fuel and reactor performance, and develop adequate safety basis and its requirements. A BISON capability for the Modeling and Analysis of Advanced Metallic Fuels Principal Investigator: Cetin Unal and Christopher Matthews Collaborators: Garrison Stevens, Jack Galloway, Naveen Prakash, Daniel Versino, Ohio State University Collaborators (NEUP): Jinsuo Zhang, Xian Li, Jeremy Isler