Accident tolerant fuels (ATF) are being developed to enhance the safety margin of commercial nuclear reactors while maintaining or improving economic efficiency of nuclear power; however the behavior of these materials has not been fully integrated in simulation tools yet. Internationally, a strong focus is put on the U₃Si₂ fuel and composite silicon carbide cladding. A research version of the Falcon fuel behavior code, in which a creep models for both fuel and cladding have been implemented, has been developed at PSI as part of multi-physics assessment of ATF concepts. This Falcon version allows assessing the performance of U₃Si₂/SiC compared to that of UO₂/Zry-₄. The comparison is performed for operating conditions in a PWR as well as a RIA transient, which is considered a challenging scenario for the ATF cladding material.