This paper describes an Eulerian/Lagrangian two-phase model for nucleating supercooled steam laden with large droplets. The model considers conditions where large pre-nucleated droplets (entering from boundaries or inlets) interact with those formed locally by homogeneous nucleation during rapid expansion of the flow. This scenario is often encountered in steam systems where secondary nucleation is present. The relative effects of expansion rate, droplet sizes and local wetness determine the degree of local supercooling available for secondary nucleation. Parametric results are presented along with comparison to experimental results (to validate certain limiting cases) for a two-dimensional Laval nozzle and turbine cascade.