This paper describes current analysis and modeling results of large-scale steam explosion experiments. For the large-scale experiments, a transient one-dimensional explosion model was developed that can qualitatively predict the trends in the experimental data. The model employs a description of vapor film collapse and subsequent fuel fragmentation by thermal and mechanical means. In addition, a simple empirical explosion model was developed and incorporated into a two-dimensional hydrodynamic computer program. This combination can be used to investigate the two-dimensional characteristics of the propagation and expansion phases for large-scale explosions.