We are working to develop high-fidelity computational models to be used to design and troubleshoot mold design for high density structural foam parts. The foam of interest is a PMDI polyurethane with a fast catalyst, such that filling and polymerization occur simultaneously. The foam is over-packed to twice or more of its free rise density, to reach the density of interest. Developing a relevant model to represent the expansion, filling, curing, and final foam properties is quite challenging. PMDI is chemically blown foam, where carbon dioxide is produced via the reaction of water and isocyanate. The isocyanate also reacts with polyol in a competing reaction, which produces the polymer. A new kinetic model is implemented, which follows a simplified mathematical formalism that decouples these two reactions. The model predicts the polymerization reaction via condensation chemistry and foam expansion kinetics by tracking the molar concentration of both water and carbon dioxide. The conservation equations, including the equations of motion, an energy balance, and three rate equations are solved via a stabilized finite element method. We assume generalized-Newtonian rheology dependent on the cure, gas fraction, and temperature. The conservation equations are combined with a level set method to determine the location of the free surface over time. On each finite element, a Rayleigh-Plesset equation is solved to determine the local bubble size over time. The bubble size and number is then used to predict the density and density gradients of the macroscopic foam. Results from the model are compared to experimental flow visualization data, bubble-size distribution, and post-test CT data for the density. *Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.