Computational models for analyzing in-reactor behavior of metallic fuel pins in liquid-metal reactors under steady-state conditions are developed and implemented in the Metal fuel performance Analysis (computer) Code for Simulating the In-reactor behavior under Steady-state conditions (MACSIS). Sodium logging and constituent redistribution effects are considered in calculating the temperature profile. The model for the radial redistribution of the fuel constituent is based on the thermotransport theory. The fission gas release model takes multibubble size distribution into account to characterize the lenticular bubble shape and the saturation condition on the grain boundary. Finally, the clad strains are calculated from the amount of fission gas released and interface pressure. Sample calculations are performed to verify each model. The results show that in general, the predictions of MACSIS agree well with the available irradiation data.