VIPRE-02—A Two-Fluid Thermal-Hydraulics Code for Reactor Core and Vessel Analysis: Mathematical Modeling and Solution Methods

The VIPRE-02 code is a thermal-hydraulic analysis code designed to model steady-state conditions and operational transients in light water reactor cores and vessels. It uses a two-fluid representation of two-phase flow that solves conservation equations for mass, momentum, and energy for each phase. The code uses a subchannel formulation of the conservation equations but also contains an optional three-dimensional (r-θ coordinates) representation of the lower plenum for vessel modeling. The six-equation formulation is solved implicitly, by a modified Gauss-Seidel iteration procedure, and has no time step size limitation for stability. Models for phase interaction based on flow regime mapping are provided that use empirical models and correlations for heat and mass transfer at the interface and vapor generation. In addition, the code contains as an option a dynamic flow regime model, which uses an interfacial area transport equation to determine the phase interaction terms.