2017 | AFC ACCOMPLISHMENTS 157 metal fuel specific material models were modified to make use of these new features.These included UPuZr fuel (elastic, thermal, creep and swelling), HT9 (elastic, thermal and irradiation creep) and SS316 (elastic, thermal and irradiation creep) cladding materials. In addition, a new model for Na infiltration of UPuZr fuel was added to account for the changing conductivity once the fuel swelling reaches a threshold and the Na fills in the porosity. Figure 1. Comparison of the calculated cerium concentration in the fuel and cladding calculated using BISON with a PIE image showing evidence of the FCCI. Accomplishments: The primary technical goal for the BISON team related to metal fuel modeling was to evaluate and provide a preliminary capability for anisotropic swelling in order to simulate the EBR2 X447 experiment.A literature search was conducted to ascertain the prior work on anisotropic swelling behavior in metal fuels.A number of experimental observations on the extent of swelling anisotropy in both UZr and UPuZr fuels are well established in the literature. However, an analytical model to account for anisotropic swelling in metal fuel was not found.An empirical model implemented in the ALFUS code based on a small set of experimental results is the current state-of-the-art.This model has been implemented in BISON using the 1.5D capability in tensor mechanics.A 1.5D version of the X447 model is being used to evaluate the effects of anisotropic swelling on fuel and cladding deformation. Since the BISON code is transitioning the approach for computing mechanical behavior to provide a more general framework for future developments (such as anisotropic materials, cracking, 1.5D, etc.), the